Encyclopedia of meat sciences. Volume 1 [Second edition] 9780123847317, 1865843830, 0123847311, 9780123847348, 0123847346, 9780124649705, 012464970X

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ENCYCLOPEDIA OF

MEAT SCIENCES SECOND EDITION VOLUME 1

ENCYCLOPEDIA OF

MEAT SCIENCES SECOND EDITION EDITORS-IN-CHIEF

Michael Dikeman Kansas State University, Manhattan, KS, USA

Carrick Devine The New Zealand Institute for Plant and Food Research, Hamilton, New Zealand VOLUME 1

Academic Press Academic Press is an imprint of Elsevier 32 Jamestown Road, London NW1 7BY, UK 225 Wyman Street, Waltham, MA 02451, USA 525 B Street, Suite 1800, San Diego, CA 92101-4495, USA First Edition 2004 Copyright r 2014 Elsevier Ltd. unless otherwise stated. All rights reserved No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means electronic, mechanical, photocopying, recording or otherwise without the prior written permission of the publisher Permissions may be sought directly from Elsevier’s Science & Technology Rights Department in Oxford, UK: phone (+44) (0) 1865 843830; fax (+44) (0) 1865 853333; email: [email protected]. Alternatively you can submit your request online by visiting the Elsevier web site at http://elsevier.com/locate/permissions, and selecting Obtaining permission to use Elsevier material Notice No responsibility is assumed by the publisher for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions or ideas contained in the material herein, Because of rapid advances in the medical sciences, in particular, independent verification of diagnoses and drug dosages should be made British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library Library of Congress Cataloging-in-Publication Data A catalog record for this book is available from the Library of Congress ISBN (print): 978-0-12-384731-7

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Printed and bound in the United Kingdom 14 15 16 17 18 19 10 9 8 7 6 5 4 3 2 1 Project Managers: Sam Mahfoudh & Will Bowden-Green Associate Project Managers: Marise Willis & Zoey Ayres Associate Acquisitions Editor: Simon Holt Cover Designer: Alan Studholme

EDITORIAL BOARD

Editors-in-Chief Michael Dikeman Kansas State University, Manhattan, KS, USA Carrick Devine The New Zealand Institute for Plant and Food Research, Hamilton, New Zealand

Section Editors Andrzej Sosnicki Genus PIC Hendersonville, TN USA

Karl-Otto Honikel† Federal Center for Meat Research (Max Rubner Institute) Kulmbach Germany

Carrick Devine The New Zealand Institute for Plant and Food Research Hamilton New Zealand

Katja Rosenvold ANZCO Foods Ltd New Zealand

Colin Gill Agriculture and Agri-Food Canada Lacombe, AB Canada

Mohan Raj University of Bristol Bristol UK

David Gerrard Virginia Tech Blacksburg, VA USA Eero Puolanne University of Helsinki Helsinki Finland James Dickson Iowa State University Ames, IA USA Jason Apple University of Arkansas Fayetteville, AR USA Joseph Sebranek Iowa State University Ames, IA USA

Michael Dikeman Kansas State University Manhattan, KS USA Phillip Strydom Agricultural Research Council Irene South Africa Paula Cray United States Department of Agriculture Athens, GA USA Rhonda Miller Texas A& M University College Station, TX USA

†

Deceased.

v

vi

Editorial Board

Robyn Warner The University of Melbourne Victoria Australia

Steven Lonergan Iowa State University Ames, IA USA

Simon Lovatt AgResearch Hamilton New Zealand

Ted Schroeder Kansas State University Manhattan, KS USA

Stephen Smith Texas A& M University College Station, TX USA

Véronique Santé-Lhoutellier INRA Theix Saint Genes Champanelle France

CONTRIBUTORS TO VOLUME 1 MD Aaslyng Danish Meat Research Institute, Taastrup, Denmark MA Abd-Allahw A Alegría University of Valencia, Valencia, Spain KJ Allen University of British Columbia, Vancouver, BC, Canada P Allen Teagasc Food Research Centre, Dublin, Ireland JR Andersen Kirke Såby, Denmark MH Anil Cardiff University, Cardiff, UK J Arnau Arboix Institut de Recerca i Tecnologia Agroalimenter̀ ies (IRTA), Girona, Spain

TJ Braggins Analytica Laboratories Ltd., Ruakura Research Center, Hamilton, New Zealand MS Brewer University of Illinois, Urbana, IL, USA NS Bryan Texas Therapeutics Institute, Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center at Houston, Houston, USA C Cederberg Chalmers University of Technology and SIK–the Swedish Institute for Food and Biotechnology, Gothenburg, Sweden A Cilla University of Valencia, Valencia, Spain R Clarke Milmeq Ltd., Penrose, Auckland, New Zealand

MC Aristoy Instituto de Agroquímica y Tecnología de Alimentos (CSIC), Valencia, Spain

SP Cobb Ministry for Primary Industries, Wellington, New Zealand

T Astruc INRA de Clermont-Ferrand-Theix, Saint Genes̀ Champanelle, France

J Comaposada Beringues Institut de Recerca i Tecnologia Agroalimenter̀ ies (IRTA), Girona, Spain

R Barberá University of Valencia, Valencia, Spain L Basu The Ohio State University, Columbus, OH, USA C Bejerholm Danish Meat Research Institute, Taastrup, Denmark J Beld Oscar Mayer Foods SG Bhandare University of Nottingham, Leicestershire, UK JA Boles University, Animal Bioscience Building, Bozeman, MT, USA M Bonneau UMR SENAH, INRA, Saint Gilles, France YH Brad Kim Purdue University, West Lafayette, IN, USA w

Deceased.

S De Smet Ghent University, Melle, Belgium CE Devine The New Zealand Institute for Plant and Food Research, Hamilton, New Zealand J Efrén Ramírez-Bribiesca Colegio de Postgraduados, Texcoco, Mexico SM Ellerbeck NSF International, Manhattan, KS, USA SBM El-Magoli Cairo University, Cairo, Egypt DM Ferguson CSIRO Livestock Industries, Armidale, NSW, Australia A Fischer Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse, Stuttgart, Germany M Flores Instituto de Agroquímica y Tecnología de Alimentos (CSIC), Valencia, Spain

vii

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Contributors to Volume 1

M Gibis Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse, Stuttgart, Germany F Gonzaĺ ez-Schnake ́ , Chile Universidad de Concepcioń , Chillan P Gou Botó Institut de Recerca i Tecnologia Agroalimenter̀ ies (IRTA), Girona, Spain

AL Kerrihard University of Georgia, Athens, GA, USA CL Knipe Ohio State University, Columbus, OH, USA N Lambe Scotland's Rural College, Edinburgh, UK C Lambel Ceyrat, France

GL Guadalupe University of Valencia, Valencia, Spain

K Lee University of Missouri, Columbia, MO, USA

I Guerrero-Legarreta ́ oma Metropolitana, Mexico City, Universidad Auton Mexico

PP Lewickiw

HF Ho SilverPeak Pte Ltd., Singapore K von Holleben BSI Schwarzenbek, Schwarzenbek, Germany KO Honikelw DL Hopkins NSW Department of Primary Industries, Cowra, NSW, Australia IH Hwang Biotechnology Chonbuk National University, Jeonju City, Korea K Immonen University of Helsinki, Helsinki, Finland C James The Grimsby Institute of Further & Higher Education (GIFHE), North East Lincolnshire, UK SJ James The Grimsby Institute of Further & Higher Education (GIFHE), North East Lincolnshire, UK A Jang Kangwon National University, Chuncheon, Republic of Korea ́ ez Colmenero F Jimen Instituto de Ciencia y Tecnología de Alimentos y ́ (ICTAN-CSIC) (Formerly Instituto del Frío), Nutricion Ciudad Universitaria, Madrid, Spain

SC MacDiarmid Ministry for Primary Industries, Wellington, New Zealand NT Madsen Danish Technological Institute, Roskilde, Denmark RW Mandigo University of Nebraska-Lincoln, Lincoln, NE, USA RK Miller Texas A& M University, College Station, TX, USA E Mills Penn State University, PA, USA G Monin INRA, Saint Genes̀ Champanelle, France I Muñ oz Moreno Institut de Recerca i Tecnologia Agroalimenter̀ ies (IRTA), Girona, Spain MT Nú ñ ez de Gonzaĺ ez Universidad de Oriente Núcleo Nueva Esparta, Isla de Margarita, Venezuela, and University of East Sparta New Core, Isla de Margarita, Venezuela FM Nattress Agriculture and Agri-Food Canada, Lacombe, AB, Canada EA Navajas ́ Agropecuaria, Instituto Nacional de Investigacion Canelones, Uruguay JU Nielsen Danish Technological Institute, Roskilde, Denmark

P Joseph Kalsec, Inc., Kalamazoo, MI, USA

HS Norli Norwegian Veterinary Institute, Sentrum, Norway

JT Keeton Texas A& M University, College Station, TX, USA

R Nova University of Nottingham, Nottingham, UK

w

w

Deceased.

Deceased.

Contributors to Volume 1

ix

HW Ockerman The Ohio State University, Columbus, OH, USA

PR Sheard University of Bristol, Bristol, UK

EV Olsen Danish Technological Institute, Roskilde, Denmark

G Simm Scotland's Rural College, Edinburgh, UK

K Palka ́ , Poland University of Agriculture, Krakow

JJ Sindelar University of Wisconsin, Meat Science & Muscle Biology Laboratory, Madison, WI, USA

D Parthasarathy Texas Therapeutics Institute, Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center at Houston, Houston, USA CT Pedersen Eurofins Steins Laboratory A/S, Vejen, Denmark RB Pegg University of Georgia, Athens, GA, USA A Pisula Warsaw University of Life Sciences – SGGW, Warsaw, Poland RR Prather University of Missouri, Columbia, MO, USA E Puolanne University of Helsinki, Helsinki, Finland M Reig Universidad Politécnica de Valencia, Valencia, Spain I Richards Meat and Livestock Australia, South Brisbane, QLD, Australia

DR Smith Texas A& M University, College Station, TX, USA SB Smith Texas A& M University, College Station, TX, USA NC Speer Western Kentucky University, Bowling Green, KY, USA EJ Squires University of Guelph, Guelph, ON, Canada PE Strydom Animal Production Institute, Irene, South Africa GA Sullivan University of Nebraska-Lincoln, Lincoln, NE, USA SP Suman University of Kentucky, Lexington, KY, USA MA Tørngren Danish Meat Research Institute, Taastrup, Denmark K Tessanne University of Missouri, Columbia, MO, USA

M Rose The Food and Environment Research Agency, Sand Hutton, York, UK

F Toldrá Instituto de Agroquímica y Tecnología de Alimentos (CSIC), Valencia, Spain

RE Rust Iowa State University, Ames, IA, USA

S Wang University of British Columbia, Vancouver, BC, Canada

AGP Samaranayaka POS Bio-Sciences, Saskatoon, SK, Canada

E W˛esierska ́ , Poland University of Agriculture, Krakow

V Santé-Lhoutellier INRA, Saint Genes̀ Champanelle, France

J Weiss Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse, Stuttgart, Germany

JW Savell Texas A& M University, College Station, TX, USA MW Schilling Mississippi State University, Mississippi State, MS, USA JG Sebranek Iowa State University, Ames, IA, USA F Shahidi Memorial University of Newfoundland, St. John's, NL, Canada

DN Wells AgResearch Ltd., Hamilton, New Zealand YL Xiong University of Kentucky, Lexington, KY, USA CK Yost University of Regina, Regina, SK, Canada B Zondagh Animal Production Institute, Irene, South Africa

GUIDE TO USING THE ENCYCLOPEDIA Structure of the Encyclopedia The material in the encyclopedia is not arranged by ordinary alphabetical order, but by alphabetical order according to 97 principal topic areas taken to allow all papers belonging to each principal topic to appear together in the same volume. Within each principal subject, article headings are also arranged alphabetically, except where logic dictates otherwise. There are four features that help you find the topic in which you are interested: 1. The contents list. 2. Cross-references to other relevant articles within each article. 3. A full subject index. 4. Contributors list. 1

Alphabetical Contents List

The alphabetical contents list, which appears at the front of each volume, lists the entries in the order that they appear in the encyclopedia. It includes both the volume number and the page number of each entry. 2

Cross-References

All of the entries in the encyclopedia have been crossreferenced. The cross-references, which appear at the end of an entry as a See also list, serve four different functions: i. To draw the reader’s attention to related material in other entries.

ii. To indicate material that broadens and extends the scope of the article. iii. To indicate material that covers a topic in more depth. iv. To direct readers to other articles by the same author(s). Example The following list of cross-references appears at the end of the entry Meat, Animal, Poultry and Fish Production and Management: Antibiotic Growth Promotants.

See also: Chemical Analysis: Sampling and Statistical Requirements; Standard Methods. Foodborne Zoonoses. Growth of Meat Animals: Metabolic Modifiers. Microorganisms and Resistance to Antibiotics, the Ubiquity of: Antibiotic Resistance by Microorganisms. Residues in Meat and Meat Products: Feed and Drug Residues; Residues Associated with Meat Production

3

Index

The index includes page numbers for quick reference to the information you are looking for. The index entries differentiate between references to a whole entry, a part of an entry, and a table or figure. 4

Contributors

At the start of each volume there is list of the authors who contributed to that volume.

xi

PREFACE The Encyclopedia of Meat Sciences, second edition, an extensive revision of the first edition published in 2004, covers all the essential meat topics, ranging from animal production, processing, analytical procedures, and food safety, to final consumption including health issues and nutritional aspects. There are more than 230 articles and these provide a greater breadth of coverage than any existing work on meat science. In addition to publication in print, the Encyclopedia is also available for licensing online that can allow regular updating. The articles are designed to bring a nonexpert up to a level of understanding the interactions among the various disciplines covered in the articles. Most articles are 3000–4000 words long and include a list of Further reading and Websites to expand the content beyond the immediate scope of this work. The Encyclopedia is, therefore, a valuable resource for several levels of education and experience. The Editors gratefully acknowledge the contributions of the authors of the articles and the Editorial Advisory Board.

The board not only proposed subjects to be covered, but also found contributors and then reviewed the articles. The work involved in an Encyclopedia such as this requires an extensive interactive cooperation among the Editors, the Editorial Advisory Board, the contributors, and the publishers, particularly the staff of the Major Reference Works division of Elsevier. The staff included Nancy Maragioglio, Donna de Weerd-Wilson, Anna Gebicka, Cari Owen, Will Bowden-Green, Sam Mahfoudh, Zoey Ayres, and Marise Willis. The Editors are particularly grateful to Cari, Will, and Sam, who worked very closely with us and who diligently pursued all avenues to obtain contacts with contributors, maneuvered around obstacles, facilitated the day-to-day management, and linked everyone together to meet the deadlines. Michael Dikeman and Carrick Devine Editors, August 2014

xiii

INTRODUCTION Meat consumption by hunter–gatherers predated the agricultural revolution. Consumption of meat and fish runs in parallel with human development that is still in process. Humans and animals have now coexisted for thousands of years for their mutual benefit, even though their relationship is changing. Meat does not come from a single, or even a few, animal species, but is derived from a wide variety of species ranging from poultry to pigs, cattle, sheep, goats, and wild game to thousands of species of fish. While many of these species are now intensively farmed, some still coexist with nomadic tribes, whereas, others are raised by families in small village communities, or are even hunted by remnants of hunter–gatherer communities. The second edition of the Encyclopedia of Meat Sciences discusses how the domesticated species evolved; the wide range of harvesting methods for animals, poultry and fish; the historical changes in production, processing and nutritional value, including the beneficial effects of optimum amounts of meat in a diet. The meat industry is based on obtaining animals, poultry, and fish from pastures, feedlots and specialized intensive production systems, and from extractive industries such as fishing. It is understandable, therefore, that the genetics and management of animals and production systems are prominent in the Encyclopedia. However, the broad field of meat science is much more than harvesting animals and processing meat from them. It includes issues such as preslaughter stress and its effects on meat quality; religious issues; animal welfare; and humane slaughter techniques, all of which are extremely important to ensure that meat quality, cultural issues, and market requirements are harmonized. Processing methods for the various species are different, but they have all historically developed to ensure, either by conscious design or by experience, that the underlying principles of physiology and biochemistry in the conversion of muscle to meat are optimized. Biochemistry and physiology are extremely important and fundamental disciplines, because they explain how unfortunate, undesirable processing defects such as PSE or cold shortening and toughening can occur and can be avoided. Progress in this area has also enabled significant changes in production and subsequent quality since the first edition of the Encyclopedia of Meat Sciences in 2004. Understanding these changes requires an appreciation of the structure of carcass tissues, from gross carcass attributes to consideration and understanding of changes at the ultrastructural level. The form and function of muscle tissues, how they change through growth, how they impinge on meat quality, and the way that connective tissue and fat can be major contributors to the final product quality are all covered in these pages. Topics such as cold shortening that can cause meat toughening or inhibition of tenderisation are explained, as well as how procedures such as electrical stimulation evolved to prevent these problems. Assessment of meat quality from measurements such as muscle pH, tenderness prediction through spectral measurements on uncooked meat, color changes on display and storage, and reduction of microbial

contamination are critical for many aspects of the meat industry and are also discussed. There have been many and significant advances in meat animal production based on genetic, nutrition, growth biology, and metabolic modifier research. In regard to meat processing, advances in refrigeration and freezing technology, which is the foundation of perhaps the most important changes ever encountered for food is discussed. Even so, such advances also depend on the way in which microbiology and packaging are integrated to ensure wholesome products with a long shelf life, minimal spoilage, and desirable sensory attributes. However, there are many other ways to preserve food that are also important. Of ever-increasing importance is the topic of food safety, which must receive extensive attention because meat is a perishable product and is critical for a high quality of living and even for human survival. Meat marketing and pricing in all its forms, from wet markets to hotel, restaurant and institutional trade, and transportation are also important. Whole-tissue meat is usually cooked, so, many of the desirable attributes such as flavor development relate to the temperature interactions with various proteins and sugars during cooking. Other cuts are processed in various ways, from smoking to mincing to sausages and the technologies involved are covered. Not all muscles or cuts of meat are suitable for the same cooking and preparation methods. Therefore, out of necessity, a vast range of highly desirable products has evolved with variations from one ethnic background to another. Other products are merchandized through fast-food restaurants. One can now consume a hamburger in China that is almost identical to that in Chile or in the United States owing to a consistency of product specifications that has become universal. Meat is not only a major source of quality protein and some vitamins and minerals; it often forms the central part of a meal, and is desirable to have the appropriate flavors, aromas, and appearance to conform to the expectations and the way meat is used in various cultures. This second edition of the Encyclopedia of Meat Sciences also covers controversial health-related aspects of meat consumption and this aspect needs considerably more research. In recent years, the ready availability of meat and other foods has given rise to some health concerns. However, the issues are not always what they seem. The positive and potential negative healthrelated aspects of meat eating are addressed by experts in dietary and health aspects of meat consumption, but the effect of a single food item should not be considered in isolation. The wide coverage of topics will ensure that this second edition of the Encyclopedia of Meat Sciences will be an important resource for students or professionals with an interest in meat science or those engaged in the livestock and meat industries. Most of the articles in the second edition are not only a revision of those in first edition but there are additional areas covered. The relatively short nature of the articles makes the Encyclopedia easy and interesting to read. Michael Dikeman and Carrick Devine Editors, August 2014

xv

CONTENTS OF ALL VOLUMES Editorial Board Contributors to Volume 1 Guide to using the Encyclopedia Preface Introduction

v vii xi xiii xv

VOLUME 1 A ADDITIVES

1

Extenders E Mills

1

Functional E Mills

7

ANIMAL BREEDING AND GENETICS

12

DNA Markers and Marker-Assisted Selection in the Genomic Era EA Navajas

12

Traditional Animal Breeding N Lambe and G Simm

19

ANIMAL HEALTH RISK ANALYSIS SP Cobb and SC MacDiarmid

27

AUTOMATION IN THE MEAT INDUSTRY

33

Cutting and Boning R Clarke, JU Nielsen, and NT Madsen

33

Slaughter Line Operation JU Nielsen, NT Madsen, and R Clarke

43

B BACON PRODUCTION

53

Bacon CL Knipe and J Beld

53

Wiltshire Sides PR Sheard

58

BIOFILM FORMATION FM Nattress

64

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Contents of All Volumes

BIOMETHANE PRODUCTION AND CLEANUP J Efre´n Ramı´rez-Bribiesca

71

BIOPRESERVATION CK Yost

76

BIOTECHNOLOGY IN MEAT ANIMAL PRODUCTION

83

Cloning DN Wells

83

Genetically Modified Organisms in Meat Animal Production K Tessanne, K Lee, and RR Prather

92

BOAR TAINT: BIOLOGICAL CAUSES AND PRACTICAL MEANS TO ALLEVIATE IT EJ Squires and M Bonneau

97

BY-PRODUCTS

104

Edible, for Human Consumption HW Ockerman and L Basu

104

Hides and Skins HW Ockerman and L Basu

112

Inedible HW Ockerman and L Basu

125

C CANNING I Guerrero-Legarreta

137

CARCASS CHILLING AND BONING HW Ockerman and L Basu

142

CARCASS COMPOSITION, MUSCLE STRUCTURE, AND CONTRACTION T Astruc

148

CHEMICAL ANALYSIS

167

Analysis of Final Product Composition for Labeling TJ Braggins

167

Physicochemical Analysis Methods JR Andersen and CT Pedersen

173

Raw Material Composition Analysis JG Sebranek

180

Sampling and Statistical Requirements MW Schilling

187

Standard Methods HS Norli

193

CHEMICAL ANALYSIS FOR SPECIFIC COMPONENTS

200

Curing Agents KO Honikelw

200

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Deceased.

Contents of All Volumes

xix

Major Meat Components F Toldra´, M Flores, and MC Aristoy

206

Micronutrients and Other Minor Meat Components A Cilla, A Alegrı´a, R Barbera´, GL Guadalupe, and F Toldra´

212

Veterinary Drug Residue Analysis F Toldra´ and M Reig

217

CHEMICAL AND PHYSICAL CHARACTERISTICS OF MEAT

222

Adipose Tissue SB Smith and DR Smith

222

Chemical Composition JT Keeton, SM Ellerbeck, and MT Nu´n˜ez de Gonza´lez

235

Color and Pigment SP Suman and P Joseph

244

Palatability RK Miller

252

pH Measurement KO Honikelw

262

Protein Functionality YL Xiong

267

Water-Holding Capacity MS Brewer

274

CHEMISTRY AND PHYSICS OF COMMINUTED PRODUCTS

283

Emulsions and Batters RW Mandigo and GA Sullivan

283

Nonmeat Proteins F Jime´nez Colmenero

289

Other Ingredients HW Ockerman and L Basu

296

Spices and Flavorings HW Ockerman and L Basu

302

CLASSIFICATION OF CARCASSES

307

Beef Carcass Classification and Grading P Allen

307

Pig Carcass Classification EV Olsen

316

CONNECTIVE TISSUE: STRUCTURE, FUNCTION, AND INFLUENCE ON MEAT QUALITY T Astruc

321

CONVERSION OF MUSCLE TO MEAT

329

Aging CE Devine

329

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Deceased.

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Contents of All Volumes

Color and Texture Deviations G Monin and V Sante´-Lhoutellier

339

Glycogen E Puolanne and K Immonen

346

Glycolysis KO Honikelw

353

Rigor Mortis, Cold, and Rigor Shortening KO Honikelw

358

Slaughter-Line Operation and Pig Meat Quality V Sante´-Lhoutellier and G Monin

366

COOKING OF MEAT

370

Cooking of Meat C Bejerholm, MA Tørngren, and MD Aaslyng

370

Flavor Development RB Pegg and F Shahidi

377

Heat Processing Methods SJ James and C James

385

Maillard Reaction and Browning F Shahidi, AGP Samaranayaka, and RB Pegg

391

Physics and Chemistry K Palka and E W˛esierska

404

Warmed-Over Flavor RB Pegg, AL Kerrihard, and F Shahidi

410

CURING

416

Brine Curing of Meat F Shahidi, AGP Samaranayaka, and RB Pegg

416

Dry F Toldra´

425

Natural and Organic Cured Meat Products in the United States JJ Sindelar

430

Physiology of Nitric Oxide D Parthasarathy and NS Bryan

436

Production Procedures RB Pegg and JA Boles

442

CUTTING AND BONING

453

Hot Boning of Meat SJ James and C James

453

Traditional JW Savell

458

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Contents of All Volumes

xxi

D DOUBLE-MUSCLED ANIMALS S De Smet

465

DRYING PP Lewickiw, J Arnau Arboix, P Gou Boto´, J Comaposada Beringues, and I Mun˜oz Moreno

471

E ECONOMICS

480

Meat Business and Public Policy NC Speer

480

ELECTRICAL STIMULATION CE Devine, DL Hopkins, IH Hwang, DM Ferguson, and I Richards

486

ENVIRONMENTAL CONTAMINANTS M Rose

497

ENVIRONMENTAL IMPACT OF MEAT PRODUCTION

502

Primary Production/Meat and the Environment C Cederberg

502

EQUIPMENT CLEANING KJ Allen and S Wang

508

ETHNIC MEAT PRODUCTS

515

Biltong: A Major South African Ethnic Meat Product PE Strydom and B Zondagh

515

Brazil and South America F Gonza´lez-Schnake and R Nova

518

China and Southeast Asia HF Ho

522

France C Lambel and V Sante´-Lhoutellier

527

Germany M Gibis, J Weiss, and A Fischer

530

India and Pakistan SG Bhandare

538

Japan and Korea YH Brad Kim and A Jang

543

Mediterranean F Toldra´

550

Middle East SBM El-Magoli and MA Abd-Allahw

553

North America RE Rust and CL Knipe

555

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Deceased.

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Contents of All Volumes

Poland A Pisula

558

EXSANGUINATION MH Anil and K von Holleben

561

EXTRUSION TECHNOLOGY PP Lewickiw

564

VOLUME 2 F FERMENTATION D Demeyer, F Toldra´, and F Leroy

1

FISH INSPECTION M Sato and IG Gleadall

8

FOODBORNE ZOONOSES MT Destro and VB Ribeiro

17

FOREIGN BODIES LB Christensen and HD Larsen

22

FUNCTIONAL FOODS K Arihara

32

G GENOME PROJECTS

37

Modern Genetics and Genomic Technologies and Their Application in the Meat Industry – Red Meat Animals, Poultry G Plastow and H Bruce

37

GROWTH OF MEAT ANIMALS

43

Adipose Tissue Development Y-J Chen, HJ Mersmann, and S-T Ding

43

Endocrinology DH Beermann

49

Growth Patterns SJ Jones

56

Metabolic Modifiers PT Anderson, BJ Johnson, and M Dikeman

62

Muscle HJ Swatland

70

Physiology DH Beermann

75

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Contents of All Volumes

xxiii

H HAM PRODUCTION

82

Cooked Ham J Arnau Arboix

82

Dry-Cured Ham J Arnau Arboix

87

HAZARD ANALYSIS CRITICAL CONTROL POINT AND SELF-REGULATION S Eglezos and GA Dykes

92

HUMAN NUTRITION

100

Cancer Health Concerns ND Turner

100

Cardiovascular and Obesity Health Concerns PM Kris-Etherton, TD Etherton, and J Fleming

105

Macronutrients in Meat RK Tume

111

Meat and Human Diet: Facts and Myths V Sante´-Lhoutellier

118

Micronutrients in Meat B Mulvihill

124

Nutraceuticals AW Brown

130

Vegetarianism MB Ruby

135

I IRRADIATION JG Sebranek, M Dikeman, and CE Devine

140

L LABORATORY ACCREDITATION M Upmann and R Stephan

145

M MANURE/WASTE MANAGEMENT

152

Manure Management JM DeRouchey

152

Waste Management in Europe W Philipp and LE Hoelzle

157

MEASUREMENT OF MEAT QUALITY

164

Measurements of Water-holding Capacity and Color: Objective and Subjective R Warner

164

xxiv

Contents of All Volumes

MEAT, ANIMAL, POULTRY AND FISH PRODUCTION AND MANAGEMENT

172

Antibiotic Growth Promotants FR Dunshea, DN D’Souza, BB Jensen, and RM Engberg

172

Beta-Agonists DH Beermann

177

Bovine and Porcine Somatotropin FR Dunshea and M Vestergaard

181

Disease Control and Specific Pathogen Free Pig Production JP Nielsen

186

Exotic and other Species LC Hoffman and D Cawthorn

190

Meat Production in Organic Farming JE Hermansen, K Horsted, and AG Kongsted

199

Poultry P Glatz and M Moore

204

Red Meat Animals R Nova and F Gonza´lez-Schnake

211

MEAT-BORNE HAZARDS, CONCEPTS AND METHODS FOR MITIGATING RISKS RELATED TO KDC Sta¨rk and JA Drewe

218

MEAT MARKETING

225

Cold Chain SJ James and C James

225

Market Requirements and Specifications M Henchion

231

Transport of Meat and Meat Products SJ James and C James

236

Wet Markets HF Ho

244

MEAT PRICING SYSTEMS GT Tonsor

248

MEAT RESEARCH INSTITUTIONS RG Kauffman

255

MEAT SPECIES DETERMINATION AH Teen Teh and GA Dykes

265

MECHANICALLY RECOVERED MEAT P Paulsen and J Nagy

270

MICROBIAL CONTAMINATION

276

Decontamination of Fresh Meat GR Acuff

276

Decontamination of Processed Meat MD Hardin

280

Microbial Contamination of Fresh Meat OA Aiyegoro

285

Contents of All Volumes

xxv

Microbial Contamination of Processed Meat OA Aiyegoro

289

MICROBIOLOGICAL ANALYSIS

294

DNA Methods A Van Stelten and KK Nightingale

294

Indicator Organisms in Meat DW Schaffner and S Smith-Simpson

301

Standard Methods AO Gill, GG Greer, and FM Nattress

306

MICROBIOLOGICAL SAFETY OF MEAT

317

Aeromonas spp. RE Levin

317

Bacillus cereus S Eglezos and GA Dykes

324

Clostridium botulinum and Botulism JW Austin

330

Clostridium perfringens R Labbe and V Juneja

335

Emerging Pathogens CO Gill and MK Youssef

340

Hurdle Technology SE Gragg and MM Brashears

345

Listeria monocytogenes RA Holley and RP Cordeiro

348

Pathogenic Escherichia coli N Fegan, KS Gobius, and GA Dykes

357

Prions TH Jones

362

Salmonella spp. A Wingstrand and S Aabo

367

Staphylococcus aureus JA Hudson

376

Thermotolerant Campylobacter AM Donnison and CM Ross

382

Viruses TH Jones

389

Yeasts and Molds DYC Fung

395

Yersinia enterocolitica J Mills

405

MICROORGANISMS AND RESISTANCE TO ANTIBIOTICS, THE UBIQUITY OF

412

Antibiotic Resistance by Microorganisms PJ Fedorka-Cray

412

xxvi

Contents of All Volumes

Potential Environmental and Wildlife Sources of Microorganisms in Meat JT LeJeune and DL Pearl

417

MINCED MEATS KO Honikelw

422

MODELING IN MEAT SCIENCE

425

Meat Quality SJ Lovatt and CE Devine

425

Microbiology P Paulsen and FJM Smulders

430

Refrigeration SJ Lovatt

436

MUSCLE FIBER TYPES AND MEAT QUALITY T Astruc

442

N NUTRIENT CLAIMS ON PACKAGING KB Harris

449

NUTRITION OF MEAT ANIMALS

455

Pigs CT Whittemore

455

Poultry V Ravindran

463

Ruminants C Reinhardt and B Faris

471

O ON-LINE MEASUREMENT OF MEAT COMPOSITION R Clarke

480

ON-LINE MEASUREMENT OF MEAT QUALITY C Borggaard

489

VOLUME 3 P PACKAGING

1

Equipment N Penney, JWS Yancey, and EJ Yancey II

1

Modified and Controlled Atmosphere DH Kropf and RA Mancini

9

w

Deceased.

Contents of All Volumes

xxvii

Overwrapping DH Kropf, JWS Yancey, and EJ Yancey II

13

Technology and Films DH Kropf, JWS Yancey, and EJ Yancey II

19

Vacuum TE Lawrence and DH Kropf

26

PARASITES PRESENT IN MEAT AND VISCERA OF LAND FARMED ANIMALS A Broglia and W Basso

34

PATENTING PRODUCTS, PROCESSES, AND APPARATUSES B Myrup and M Rachlitz

42

PHYSICAL MEASUREMENTS

50

Other Physical Measurements QT Pham

50

Temperature Measurement QT Pham

57

POTENTIAL CHEMICAL HAZARDS ASSOCIATED WITH MEAT R Nova and F Gonza´lez-Schnake

64

PREDICTION OF MEAT ATTRIBUTES FROM INTACT MUSCLE USING NEAR-INFRARED SPECTROSCOPY MM Reis and K Rosenvold

70

PRESERVATION METHODS OF ANIMAL PRODUCTS HW Ockerman and L Basu

78

PRESLAUGHTER HANDLING

84

Behavior of Cattle, Pigs, Sheep, Bison, and Deer during Handling and Transport T Grandin

84

Design of Stockyards, Lairages, Corrals, Races, Chutes, and Loading Ramps T Grandin

90

Preslaughter Handling A Velarde Calvo and A Dalmau

95

Welfare Including Housing Conditions AM de Passille´ and J Rushen

102

Welfare of Animals P Lawlis and A Allen

108

PROCESSING EQUIPMENT

114

Battering and Breading Equipment S Barbut

114

Brine Injectors RE Rust and CL Knipe

123

Mixing and Cutting Equipment RE Rust and CL Knipe

126

Smoking and Cooking Equipment RE Hanson

131

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Tumblers and Massagers CL Knipe

143

PROFESSIONAL ORGANIZATIONS RG Kauffman

147

PROTEOMIC TECHNOLOGIES AND THEIR APPLICATIONS IN THE MEAT INDUSTRY SP Suman and P Joseph

155

Q QUALITY MANAGEMENT

159

Abattoirs and Processing Plants M Upmann, J Stender, and J Trilling

159

Farm Level: Pork Quality D Newman and J Magolski

168

Farm Level: Safety and Quality of Beef DL VanOverbeke and JK Ahola

173

R REFRIGERATION AND FREEZING TECHNOLOGY

178

Applications SJ Lovatt

178

Equipment C James and SJ James

184

Freezing and Product Quality K Rosenvold

191

Principles SJ Lovatt

196

Thawing QT Pham

202

RELIGIOUS SLAUGHTER JE Shragge and MA Price

209

RESIDUES IN MEAT AND MEAT PRODUCTS

214

Feed and Drug Residues J Fink-Gremmels

214

Residues Associated with Meat Production F Bauer

221

RISK ANALYSIS AND QUANTITATIVE RISK MANAGEMENT C Heggum

226

S SAUSAGE CASINGS RE Rust and CL Knipe

235

SAUSAGES, TYPES OF

241

Cooked CL Knipe

241

Contents of All Volumes

xxix

Dry and Semidry F Toldra´ and M Flores

248

Emulsion CL Knipe

256

Fresh HW Ockerman and L Basu

261

SENSORY AND MEAT QUALITY, OPTIMIZATION OF M Dikeman and CE Devine

267

SENSORY ASSESSMENT OF MEAT MD Aaslyng, L Meinert, C Bejerholm, and R Warner

272

SLAUGHTER, ETHICS, AND THE LAW MH Anil and NG Gregory

280

SLAUGHTER-LINE OPERATION

284

Cattle DR Woerner, JA Scanga, and KE Belk

284

Other Species E Wiklund

290

Pigs H Channon

295

Poultry MW Schilling, Y Vizzier-Thaxton, and CZ Alvarado

303

Sheep and Goats CE Devine and KV Gilber

309

SMOKING

315

Liquid Smoke (Smoke Condensate) Application J Rozum

315

Traditional ZE Sikorski and I Sinkiewicz

321

SPECIES OF MEAT ANIMALS

328

Cattle MA Price

328

Finfish XM Vilanova

336

Game and Exotic Animals LC Hoffman and D Cawthorn

345

Meat Animals, Origin and Domestication M Konarzewski

357

Pigs DD Boler

363

Poultry P Mozdziak

369

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Contents of All Volumes

Sheep and Goats EL Walker and MD Hudson

374

Shellfish XM Vilanova

380

SPOILAGE, FACTORS AFFECTING

388

Microbiological CO Gill

388

Oxidative and Enzymatic J Aalhus and M Dugan

394

STUNNING

401

CO2 and Other Gases ABM Raj

401

Electrical Stunning E Lambooij

407

Mechanical Stunning B Algers and S Atkinson

413

Slaughter: Immobilization M Appelt, A Allen, and D Will

418

STUNNING AND KILLING OF FARMED FISH: HOW TO PUT IT INTO PRACTICE? H van de Vis, W Abbink, B Lambooij, and M Bracke

421

SUSTAINABLE MUSCLE FOODS INDUSTRY E Kurt and R Klont

427

T TENDERIZING MECHANISMS

431

Chemical DL Hopkins and Alaa El-Din A Bekhit

431

Enzymatic E Huff-Lonergan

438

Mechanical DL Hopkins

443

TENDERNESS MEASUREMENT RW Purchas

452

THERMOPHYSICAL PROPERTIES SJ Lovatt

460

Index

465

A ADDITIVES

Contents Extenders Functional

Extenders E Mills, Penn State University, PA, USA r 2014 Elsevier Ltd. All rights reserved. This article is a revision of the previous edition article by E Mills, volume 1, pp 6–11, © 2004, Elsevier Ltd.

Glossary Casein The predominant protein in milk. Collagen The predominant structural protein constituent of muscle connective tissues, the principle protein component of food grade gelatin. Gluten A protein component separated during milling of grain, dietary concerns with respect to gluten focus on that from wheat, barley, rye, and oats. Gums and hydrocolloids Long-chain polysaccharides derived from various plant sources or fermentation processes, give high viscosity in aqueous foodstuffs, for example, alginate, carrageenan, guar gum, locust bean gum, and xanthan gum.

Introduction Extenders are added to meat products to reduce formulation costs or to contribute a variety of functions in the product. The effect of an extender on formulation cost may be significant especially when it facilitates increased product yield via addition of water. Nevertheless, nonmeat ingredients may be added to ground, comminuted, or whole muscle meat products for a variety of reasons including increased shelf-life, reduced fluid purge, increased slicing yield, improved flavor and juiciness, improved color, or cost reduction among others.

Encyclopedia of Meat Sciences, Volume 1

Inulin and oligosaccharides Medium chain length polysaccharides comprised of glucose and fructose subunits. Nonfat dried milk solids (NFDMS) Manufactured by drying skim milk, contains 52% lactose, 36% protein, and 8.4% mineral (predominantly potassium and calcium). Retrogradation The viscosity decline in starch gels that occurs if the linear glucose chains reform into granules, accelerated by freezing and thawing. Soy flour Milled soy grits derived from dehulled, defatted soy beans, contains 47% protein, 38% carbohydrate. Starch Polysaccharide composed of glucose molecules arranged in linear and helical (amylose) and branched (amylopectin) structures.

Ingredients described as extenders typically allow for reduced product cost while serving other important functions as well. A common functional property of most extenders is waterholding. Water-holding capacity is an especially important property because most cost reduction comes from the addition of water along with the extender. Ingredients are sometimes called binders when they are used primarily for increasing the water-holding capacity of a product or also if they improve fatholding and emulsion stability. Thus, the terms extender and binder are often interchanged when referring to various ingredients. Extenders used in a particular meat product are

doi:10.1016/B978-0-12-384731-7.00108-2

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Additives | Extenders

chosen based on their specific functional properties, compatibility with the product, and cost.

Functional Properties A functional property is the ability of an ingredient to impart an economically important characteristic to the finished product in which the ingredient is used. Functional properties of extenders used in meat products include, for example, water-holding, texture modification, improvement of flavor or appearance, improvement of sliceability for luncheon meats, reduced cook loss or fluid purge, modification of heat-set or cold-set gelation, emulsification of fat, or simply improvement of flowability or mixability of a seasoning mix Table 1. Many of the functional properties of extenders depend on the ability of the material to interact with water, protein, or fat. Water-holding by an extender material is largely dependent on available charged groups and void spaces within granules of the material. Interactions of extenders with meat protein often involve charged groups along with hydrophobic interactions. Interactions with fat are largely hydrophobic but, an extender may help emulsify fat if it includes both hydrophobic and hydrophilic regions. Protein-based extenders such as soy or milk proteins may interact with meat proteins to increase cohesiveness or with fat to increase emulsion stability. Starchbased extenders such as corn or potato starch increase waterholding but may interfere with protein–protein interactions, thus weakening the protein matrix within the product. By selecting the right extenders the manufacturer can increase or decrease specific product properties to achieve a desired functional result, often with a concurrent reduction in formulation cost. Choosing the best extender for a particular application is a complex process. An ingredient such as starch may be chosen for its low cost and water-holding ability but it also imparts other properties such as pale color and a tendency to soften the product by interfering with protein–protein interactions. Another, more expensive, ingredient such as soy protein concentrate also holds water while increasing protein–protein interactions and emulsion stability. Addition of extender ingredients changes the nutrient profile of the meat product. The change may be desirable with low use rates of protein ingredients such as soy or milk increasing the protein content and often changing the amino acid composition to improve biological value. At high use rates, approaching 50% extension, protein digestibility and biological value may be decreased. Milk ingredients also add

Table 1

Functions of extenders in meat products

• Reduce formulation cost • Increase water-binding • Modify texture • Improve flavor • Modify appearance • Modify cohesiveness • Provide for heat-set or cold-set gelation • Improve nutrient profile

calcium, which is often lacking in meat products. Even calcium-reduced milk ingredients have enough remaining calcium to measurably raise the calcium content of the meat product. Extenders usually reduce the fat content of the meat product by simple dilution. However, most extenders, except cellulose ingredients, are digestible and contribute to the total calories of the product. Another significant consequence of extender addition is possible allergic responses. Soy, wheat, and milk proteins are common allergens but any protein ingredient may be allergenic in sensitive individuals. It is critical that extender materials be adequately described on the product label to let consumers know what they are buying.

Extender Addition to Meat Products Extenders may be added to meat products by direct addition to comminuted meat or, for intact muscle, by injection along with water, or by surface application in a marinade and massage system. Extenders are commonly used in certain sausage or sliced luncheon meat products where they are added along with seasonings and incorporated during mixing or chopping. In such applications the extender may be in a range of forms from finely milled powder to coarse grits or flakes. The dry extender may be rehydrated with water to form a slurry before adding it to the meat. Extender ingredients added as larger pieces such as grits or textured flakes may be visible on close examination in the finished product. Hamburger extended with soy grits and water has a different appearance than ground beef without an extender. However, the extender is usually not intended to be visible in the finished product. For whole muscle products such as ham or chicken breast extender is added as a solution or suspension in water. In this process, the ingredients are commonly referred to as binders instead of extenders. The liquid containing the binder is injected into the muscle using the same techniques as in meat curing. Only finely milled or soluble materials are suitable for this application. Care must be taken to control rehydration, swelling, or gelation of the binder in the injection system as these may lead to fouling of the injector or loss of yield control. Continuous agitation is often needed to prevent the binder from settling out of the water as the liquid sets in the injector reservoir. Additionally, binders or extenders injected into muscle tend to remain in the channels made by the injector needles. When the product is sliced the bands of binder material may be visible within the muscle. This problem is minimized by increasing the number of injection needles and decreasing the amount of material delivered by each. In some types of products the functional benefits of extenders can be realized by applying the material to the product surface as part of a marinade. Mechanical action in the form of tumbling, massaging, or mixing is required to promote incorporation of the extender material into the surface of the muscle. Penetration depth is minimal, only a few mm. Nevertheless, this approach can be used to modify surface properties of a product to improve color, texture, or reduce fluid loss.

Additives | Extenders

Functional Components of Extender Ingredients A variety of nonmeat ingredients may be used as extenders in meat products. Sources may include plant seeds, tubers, milk solids, or fermentation processes among others. But, in spite of their varied origins, the functional properties of most extenders are provided by their protein and carbohydrate components. Extender ingredients generally contain little or no fat. Water-holding capacity, flavor, texture, and visual effects of extenders in meat products depend on the types and amounts of carbohydrates and proteins present. The proportions of carbohydrates and proteins vary greatly with the plant source used. Flour, commonly milled from wheat, contains significant amounts of both starch and protein (gluten). The variety of wheat and the milling process determine the proportions of starch and protein in the flour. More complex separation processes may be used to produce specific, concentrated components from the milled seeds. Wheat gluten, a by-product commonly removed during milling of wheat flour for baking purposes, is widely used as a meat product extender, especially in European countries. Starches are commonly derived from corn, potato, rice, or wheat using specialized procedures that separate starch granules from protein and other carbohydrate components. The separation is achieved based on density or viscosity differences between starch and protein granules. Modified starches are manufactured using chemical or physical processes that impart unique functional properties to the starch and increase its cost. High-protein ingredients such as soy protein, wheat gluten, or corn protein are also produced following additional processing steps. By combining these separated, purified components, a meat extender may be created with a unique set of properties that fit a specific product. Of course, the cost of such a specialized extender would be greater than that of a simple milled flour Table 2.

Ingredients Used as Meat Extenders The list of ingredients that may be used as meat extenders is almost limitless. However, in practice only a few ingredients have found wide acceptance as extenders. Some of the more commonly used ingredients are described in the sections that follow. This is not intended to be a comprehensive listing. Instead, it is a collection of examples of commonly used ingredients or ingredients that demonstrate a unique principle. Table 2

Types of meat product extenders

• Flour – milled whole grain or grain with seed coat or germ removed • Proteins – protein fractions of grains, milk, or animal products • Native starch – starch granules fractionated from grain or tubers • Modified starch – starch granules pretreated to improve functionality • Dextrin – from partial cleavage of starch • Cellulose – long chain complex carbohydrate, dietary fiber • Hydrocolloids – longer chain, charged side groups, high hydration

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Soy Ingredients Soy protein products represent a great model for discussing extenders in meat products. They are commonly used extenders in many countries. Soy products come in various types and physical forms and serve several different functions. Soy flour is produced by pressing dehulled soybeans with a solvent to separate the soy oil. The resulting soy grits may be used directly or milled into soy flour. Soy grits or flour contain approximately 45–50% protein along with carbohydrate that imparts a distinctive ‘beany’ flavor to products. Soy flour may be heated and extruded to produce textured soy flour with a more meat-like texture compared to plain soy flour. Soy flour is an effective water-holder but in spite of its high protein content it has limited ability to participate in protein–protein interactions or fat emulsification. Soy flour may be partially purified by removal of much of the carbohydrate. The resulting soy protein concentrate (SPC) is approximately 70% protein, has much less beany flavor, and has improved protein functionality. SPC is often jet-cooked to further improve its protein functionality. Jet-cooked SPC exhibits excellent ability to interact with meat protein contributing to product firmness. It also has improved capability for fat emulsification. SPC may also be texturized by heating and extrusion to give a meat-like texture. An extraction process is used to dissolve and then precipitate certain protein fractions from the soy flour to produce isolated soy protein (ISP). This material contains 90–95% protein and exhibits almost no ‘beany’ flavor. ISP has excellent protein functionality with capability for fat emulsification and increased fluid viscosity and gelation. Like soy flour and SPC, it may be texturized by thermal extrusion. It is also used to produce spun fibers, with improved meat-like texture, which perform nicely in production of meat analogs. With each successive step from soy flour through isolated soy protein the cost of the material increases. In specific meat products or situations the improved functional properties and reduced flavor intensity of soy concentrate or isolated protein may justify the cost. However, soy flour or grits are most widely used as meat extenders. The beany flavor may become part of the product's flavor profile or seasonings may be used to mask the flavor. Dry soy flour is commonly rehydrated with 2.5–3.5 parts water for one part soy flour. The resulting slurry is added to the meat in the mixer or chopper. The added soy flour slurry may represent up to 50% of the finished meat product. Of course the amount used must be in compliance with applicable ingredient and labeling regulations. In the USA soy flour, SPC, and ISP are limited to 3.5%, 3.5%, and 2.0%, respectively, in cooked sausage products.

Milk Ingredients Milk proteins are relatively expensive but are chosen by meat processors because of their unique ability to interact with meat protein to form heat-set gels and contribute to stable emulsions. Nonfat dried milk solids (NFDMS) are derived from fluid milk by fat separation and drying. It contains approximately 36% protein including casein and lactalbumin among others. NFDMS is used in meat products to increase water-holding and reduce cook loss. In finely comminuted products it contributes

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Additives | Extenders

to improved emulsion stability. Water-holding and emulsifying capabilities of NFDMS may be improved significantly by replacing much of its calcium with sodium. For this reason, the so-called calcium-reduced NFDMS is preferred for use in meat products even though it costs more. The high lactose content of NFDMS, approximately 52%, contributes to flavor and texture of the finished product and may be considered as undesirable in certain products. In the USA, NFDMS utilization is limited to 3.5% of finished product for comminuted meats. Casein may be precipitated from milk and then resuspended as sodium caseinate. This process produces a concentrated protein (approximately 90% protein) and eliminates most of the calcium and lactose. Sodium caseinate has excellent water-holding and emulsifying properties, a mild flavor, and pale color. It tends to impart a smooth mouthfeel to fine ground sausages. In the USA, this ingredient is limited to 2.0% of finished product for comminuted meats and 1.5% of finished product for water-added ham. The whey remaining after manufacture of cheese or precipitation of casein contains whey proteins, primarily lactalbumin. The whey may be dehydrated for use as a food ingredient but the dried whey contains up to 75% lactose and over 8% ash. Instead, whey protein concentrate is often produced using an ultrafiltration system to remove lactose and minerals. Dried whey protein concentrate is approximately 80% protein, 4.5% ash, and 6% lactose. It exhibits good waterholding capacity and forms an irreversible heat-set gel when heated above 70–75 °C.

Starch Ingredients Various starches may be used as extenders in meat products. Starches are generally less expensive than protein ingredients and have low flavor and color intensity. Native starches represent stored carbohydrate in cereal grains and tubers. They are composed of two types of glucose chains, amylose (unbranched glucose) and amylopectin (branched glucose). The glucose chains are packed into starch granules within seeds (grains) or roots (tubers). The size and amylose/amylopectin makeup of the starch granule varies with plant source. Potato starch has larger granules whereas corn starch granules are small. Waxy corn starch contains only amylopectin although most starches include a mixture of amylose and amylopectin. Starch granules are insoluble in cold water. On heating in water the granules suddenly swell and hydrate, eventually producing a viscous solution in a process called gelatinization. This process accounts for the high water-holding, increased viscosity, and gelling ability of starches. The gelatinization temperature varies for starches from different plant sources. In general, starches with larger granules swell and gelatinize at lower temperatures compared to those with smaller granules. Water-holding or viscosity of starch gels may be lost if the linear glucose chains reform into granules. This process called retrogradation leads to release of water and loss of product quality. When unmodified starch is used in meat products, retrogradation is likely during extended refrigerated storage. Starch retrogradation is accelerated by freezing and thawing. Native starches are classified on the basis of their properties (viscous, watery, or stringy paste and strong or weak, clear or

opaque gel on cooling) with cereal starches (corn, wheat, rice, and sorghum) setting to a strong opaque gel on cooling. Root and tuber starches (potato, cassava, and tapioca) are highly viscous and set to a clear, weak gel on cooling. Waxy starches (waxy corn, sorghum, rice) produce very high viscosity but do not form a rigid gel. Native starches may be chemically modified to reduce gelatinization temperature or to alter viscosity or gel strength and to control retrogradation. Because most native starch granules do not gelatinize at typical meat cooking temperatures, modified starches are generally preferred for meat applications. Starch may be modified by acid or enzyme treatment, oxidation, or heating among others. Most modification processes involve partial cleavage of the starch to produce shorter glucose chains. This weakens the starch granule allowing for reduced gelatinization temperature. Viscosity and cooled gel strength are affected and the tendency for retrogradation is reduced. Modified starches are used in meat products to increase cook yield, reduce fluid purge, increase product firmness, and improve sliceability. Overall firmness of the product may be increased due to reduction in free water. Certain starches may be used along with added water as fat replacers. Starches generally do not interact well with meat proteins so they can be used to reduce rubbery character in very low-fat products. The increased fluid viscosity produced by the starch is said to contribute an oily texture during chewing. This property is useful in fat replacement. Under some circumstances starches may cause reduced adhesion among meat pieces in restructured products. This is especially true if the starch is not injected but added in the blender or massager. The combination of starch source and modification process is critical in determining the performance of starch in a meat product. Some practical issues arise when using starches in injection systems. Because the granules are not soluble, there is a tendency for rapid settling of the starch in the injector reservoir or other containers where the brine is allowed to set. The starch may settle out in the brine pump itself if it is stopped for a time. Continuous agitation is needed to keep the granules suspended during operations and the pump should be rinsed immediately after use. When using modified starches, care must be taken to assure that the temperature in the pumping system does not rise high enough to trigger gelatinization. The resulting change in viscosity can lead to loss of process control and possible equipment damage.

Inulin and Oligofructose Some plants such as chicory, garlic, or onion do not produce much starch but instead store carbohydrate in the form of inulin and oligofructose. These are polysaccharides comprised of glucose and fructose subunits with varying chain length. Nutritionally, inulin and oligofructose are considered soluble dietary fibers. They are only minimally digested and do not elevate blood sugar levels. Inulin from some plants such as chicory root has a slightly sweet taste. When dissolved in water they impart a slippery, oily mouth-feel that may be quite beneficial in low-fat meat products. Thus, use of inulin in meat products is mostly as part of fat replacement system with

Additives | Extenders water. Inulin gel improves the texture of low-fat meat products. It also improves water-holding and has been shown to stabilize foams and emulsions in nonmeat food systems.

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holding, gelling, and antibacterial properties. It is used in processed meats as a binder and extender and to enhance product flavor. Deheated mustard is a common ingredient in cooked sausages where it contributes to water-binding, fat emulsification, color, and flavor.

Gums and Hydrocolloids Gum is a term that refers to a group of long-chain polysaccharides characterized by the ability to give highly viscous solutions at low concentrations. Ingredients in this group include exudate gums, seaweed gums, microbial gums, seed gums, and certain starch or cellulose derivatives. Ingredients in this category are used throughout the food industry but have found only limited use in processed meats. Unlike classical meat extenders, gums are commonly used at very low concentrations to improve yield, texture, and sliceability and to reduce fluid purge in products with high added water. The cost of gums is usually higher than for other extender ingredients but their exceptional performance may offset the cost. The most commonly used gum or hydrocolloid in meat products is carrageenan. Carrageenan is a seaweed-derived gum extracted from red kelp. It is composed of linear galactose chains with varying amounts of sulfate side chains that contribute to its water-binding and gelling properties. There are three types of carrageenan, identified as kappa, iota, and lambda. On cooling, kappa carrageenan forms a rigid, brittle gel that tends to release fluid during storage. Iota carrageenan forms a weaker, more elastic gel that is reasonably stable through refrigerated storage, freezing, and thawing. Carrageenan gels may be melted and reformed repeatedly. Lambda carrageenan is used for thickening and viscosity but does not form a cold-set gel. In meat products, mixtures of kappa and iota carrageenan are combined in varied proportions for different applications. Benefits expected from use of carrageenan include improved cook yield, reduced fluid purge, improved sliceability and cohesiveness. Carrageenan has been used along with water in reduced fat products to improve juiciness and texture. Carrageenan is often used at a concentration of approximately 1% of meat weight. Highly refined carrageenan ingredients may give satisfactory results at concentrations of less than 0.5% of meat weight. USDA limits use of carrageenan to 1.5% of finished product for cured meat products.

Flavorings and Seasonings as Extenders Proteins from plant or animal sources are commonly subjected to partial hydrolysis or other modifications to develop flavorings for food products. Such flavor ingredients appear on the product label and are regulated separate from similar proteins used as extenders. In most cases flavoring ingredients are considered to be self-limiting and thus are allowed at concentrations ‘sufficient for purpose.’ The hydrolysis process may be quite minimal and the flavor intensity low so that a considerable quantity is needed to alter product flavor. In this situation the meat processor may also consider water-holding and texture benefits in addition to the flavor contribution of the ingredient. Seasoning ingredients may be an unconventional source of extender materials. An example is mustard seed. Ground mustard is a high protein (26–38%) ingredient with water-

Animal-Derived Extender Ingredients Consumer resistance to other-species ingredients has reduced the popularity of several animal-derived extender ingredients. Nevertheless, these ingredients are still available and in use for many meat products. Gelatin is probably the most widely used of these ingredients. Most gelatin protein is extracted from animal skins, bovine or porcine. Gelatin takes up water on heating and forms a reversible cold-set gel. It is typically added to processed meat products to reduce purge during refrigerated storage. Raw collagen in the form of powdered skin or muscleconnective tissue is also utilized. It has much lower cost than gelatin and reduced functional properties. This material takes up water on heating but is not soluble, so it is not easily used in injection systems. Blood serum proteins have excellent water-binding, foaming, and emulsifying capabilities. They may be particularly useful in hotdogs and luncheon meats where all these properties are desired.

See also: Additives: Functional. Chemical and Physical Characteristics of Meat: Protein Functionality; Water-Holding Capacity. Chemistry and Physics of Comminuted Products: Emulsions and Batters; Nonmeat Proteins; Other Ingredients. Processing Equipment: Brine Injectors

Further Reading Berry, B.W., 1997. Sodium alginate plus modified tapioca starch improves properties of low fat beef patties. Journal of Food Science 62, 1245–1249. Chavez, J., Henrickson, R.L., Rao, B.R., 1986. Collagen as a hamburger extender. Journal of Food Quality 8 (4), 265–272. Correia, L.R., Mittal, G.S., 2000. Functional properties of some meat emulsion extenders. International Journal of Food Properties 3 (3), 353–361. Eilert, S.J., Mandigo, R.W., 1997. Use of additives from plant and animal sources in production of low fat meat and poultry products. In: Pearson, A.M., Dutson., T.R. (Eds.), Production and Processing of Healthy Meat, Poultry and Fish Products, vol. 11. Glasgow, UK: Blackie Academic & Professional, pp. 210–225. Janssen, F.W., Voortman, G., de Baaij, J.A., 1987. Detection of wheat gluten, whey protein, casein, ovalbumin, and soy protein in heated meat products by electrophoresis, blotting, and immunoperoxidase staining. Journal of Agricultural and Food Chemistry 35, 563–567. McCormick, R.D., 1985. Numerous functional properties govern starch selection. Prepared Foods 154 (5), 173–174, 177. Miles, C.W., Ziyad, J., Bodwell, C.E., Steele, P.D., 1984. True and apparent retention of nutrients in hamburger patties made from beef or beef extended with three different soy proteins. Journal of Food Science 49, 1167–1170. Mittal, G.S., Usborne, W.R., 1985. Meat emulsion extenders. Food Technology 39, 121–130. Reitmeier, C.A., Prusa, K.J., 1990. Addition of corn gluten meal and zein to ground pork of various fat percentages. Journal of Food Quality 13, 271–281. Tarte, R., 2009. Ingredients in Meat Products: Properties, Functionality and Applications. New York, NY: Springer, 419 pages. Verbeken, D., Neirinck, N., Van der Meeren, P., Dewettinck, K., 2005. Influence of kcarrageenan on the thermal gelation of salt soluble meat proteins. Meat Science 70, 161–166.

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Zeidler, G., Pasin, G., Luh, B.S., Thompson, J.F., Rice, R.D., 1989. Reducing cooking time, yield losses and energy utilization of salisbury steaks as affected by various meat extenders and meat composition. Journal of Foodservice Systems 5 (3), 215–236.

Relevant Websites http://www.fmcbiopolymer.com/Food/Ingredients/Carrageenan/Introduction.aspx Carrageenan/Introduction, FMC BioPolymer.

http://www.foodadditives.org/food_gums Food Gums, International Food Additives Council. http://www.soyinfocenter.com/index.php Soy Info Center. http://en.wikipedia.org/wiki/Starch Wikipedia entry on Starch.

Functional E Mills, Penn State University, PA, USA r 2014 Elsevier Ltd. All rights reserved. This article is a revision of the previous edition article by E Mills, volume 1, pp 1–6, © 2004, Elsevier Ltd.

Glossary Bacteriocin An antimicrobial protein produced by certain bacteria. Comminuted meat The meat that has been ground or otherwise divided into very small particles. Essential oil A volatile oil comprising aromatic components of spices that are responsible for distinctive aroma or flavor. Maillard browning A chemical reaction between carbohydrates and proteins leading to a brown color with development of cooked flavor.

Regulations Regulation of functional ingredients in meat products is quite variable around the world. No attempt will be made here to address specific regulatory issues for functional ingredients. Nevertheless, some general observations might be appropriate. Ingredients that impart obvious flavor or visual properties, such as salt and spices, are often considered to be self-limiting and are often unrestricted. Ingredients, such as sodium nitrite and sodium nitrate, can be quite toxic and thus are closely regulated in most parts of the world. Certain ingredients that might be improperly used to deceive an unwitting customer are also regulated in most countries. Examples in this category include sodium phosphates that contribute to increased water-holding ability or reducing agents that may stabilize color, even when the product is noticeably spoiled. In addition to these intuitively obvious regulations, the decisions to regulate specific ingredients are often a matter of tradition or circumstance. Thus, meat manufacturers often encounter a confusing patchwork of regulations when they market their products in other countries.

Adding Functional Ingredients to Meat Products The addition of functional ingredients to meat products may be achieved using various methods, depending on the properties of the functional ingredients and the meat products. For comminuted or heavily macerated meats, all types of ingredients are easily dispersed by mixing or massaging. Mixing is a rapid process requiring only minutes to achieve uniform distribution of ingredients. Addition of ingredients to intact muscle is more complex. Low molecular weight, easily soluble ingredients such as salt or nitrite may be added by surface application of the dry ingredients, by injection of a water solution into the meat, or by immersion of the meat in a water solution. Injection is quite rapid whereas surface application or immersion requires days or weeks for ingredients to diffuse

Encyclopedia of Meat Sciences, Volume 1

Monosodium glutamate A sodium salt of glutamic acid and a potent activator of umami taste sensor. Myoglobin A red pigment found in meat, especially red meat. Nitrosamine A compound resulting from reaction of nitric oxide with secondary amine, some of which are carcinogenic. Nitrosylhemochrome The compound responsible for the familiar pink color of cured meat.

throughout the intact muscle. Larger molecular weight or insoluble ingredients might be added by injecting a suspension of the ingredients. Continuous agitation is needed to keep the ingredients in suspension during injection. Also, the suspended materials tend to remain in the path opened by the injection needle and become visible when the finished product is sliced.

Functional Ingredients Salt Salt (sodium chloride) is the most commonly used functional ingredient in meat product manufacture. It is used primarily for flavor with microbial inhibition, extension of shelf life, and increased protein hydration as secondary functions. Choices relating to the amount of salt to formulate in a product are usually based on taste preferences of customers. Finished product salt concentrations of 1.5−2.5% are common for processed, ready-to-eat meat products. Microbial inhibition and extended shelf life from salt addition are achieved by reducing water activity and, in some cases, by increasing the chloride ion content in the product. With very high salt content (6% or more), the product may be made shelf-stable due to reduced water activity. Such a product would have an intense salty flavor. Salt increases water-holding in meat protein systems and soluble protein in comminuted meat products. Much of the protein that is brought into solution with addition of salt is myosin. Soluble myosin has excellent emulsification and gelling properties. As a result, salt addition is critical for creating a stable and emulsion-like structure in finely comminuted products such as hot dogs.

Nitrite Nitrite (sodium nitrite or potassium nitrite) is included in many processed meat products for the purpose of inhibiting

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Additives | Functional

spore-forming microorganisms, especially Clostridium botulinum, and for stabilizing color and flavor. Meat products containing nitrite are commonly referred to as cured meat products. On addition to meat products, nitrite is reduced to nitric oxide, and this reactive intermediate accounts for most of the functions of nitrite. When nitric oxide from nitrite binds to the iron atom within myoglobin, its pigment properties are changed to a heat-stable form. This so-called pigment stabilization due to nitrite/nitric oxide leads to meat products that retain their pink color even after heating to well done. This heat-stable pink color, nitrosylhemochrome, is an identifying character of products cured with nitrite. In addition to its effect on meat color, nitrite also influences meat flavor. Although nitrite or nitric oxide, at the low concentration used in meat curing, do not directly impart much flavor, it plays an important role in controlling lipid oxidation. When fresh meat products are cooked, a number of physical and chemical changes lead to accelerated oxidation of unsaturated fatty acids. This oxidation pathway is initiated, in part, by iron released from myoglobin and perpetuated by continuous formation of free radicals from the oxidized fatty acids. The resulting off-flavors are sometimes called warmed-over flavor. In cured meats, two mechanisms cooperate to limit lipid oxidation. First, nitric oxide stabilizes the heme iron in myoglobin and second, nitric oxide reacts with the free radicals to produce a nonreactive product and effectively stop the oxidation chain reaction. These important functions help cured meat products maintain their desirable flavor through extended storage. In spite of its various benefits, nitrite is a toxic material with a lethal dose for humans of 22–23 mg per kg of body weight. The low amounts used in cured meat products, 200 mg per kg or less, virtually eliminate any risk of toxicity through consumption of cured meats. In addition to its direct toxicity, nitrite might react with certain amino acids to produce nitrosamines, some of which are carcinogenic. The nitrosamine-producing reaction is favored by high temperatures and acidic conditions. The high temperature developed when frying sliced bacon is known to lead to nitrosamine formation if the residual nitrite content is high. This occurrence is minimized by using a lower ingoing nitrite level for bacon and by including reducing agents that help deplete residual nitrite before frying.

Nitrate There is currently little use of nitrate (sodium or potassium nitrate) in cured meat products. Nitrate is a precursor of nitrite in meat curing. Unlike nitrite, nitrate is comparatively stable in meat products. It reacts slowly, through reduction by microbial enzymes, to release nitrite over an extended period of time. Nitrate use is limited to products such as dry sausage, Prosciutto or Parma ham, and dry cured products that require long curing and aging times. Nitrate is much less toxic than nitrite and is found in many foods including fresh vegetables and drinking water.

Nitrate from Plant Sources Consumer interest in ‘Natural’ labeled products in the USA has lead meat processors to manufacture products using nitrate

found in certain plant-derived ingredients. Dehydrated celery juice powder is one commonly used ingredient. Such meat products, manufactured without the use of pure sodium nitrite or sodium nitrate, must be labeled as ‘Uncured.’ Nevertheless, the naturally occurring nitrate in celery juice powder may be converted to nitrite leading to typical cured meat properties. The shelf life, however, and especially cured color, of these ‘Naturally Cured’ products are considerably reduced compared with conventionally cured products.

Phosphate Phosphates used in meat processing are usually alkaline polyphosphates. Sodium tripolyphosphate is a very commonly used linear polymer of three phosphate units. Other longer chain polymers can be used, but pH and buffering benefits of phosphate are reduced at longer chain lengths. On addition to meat products, the alkaline phosphate raises the pH away from the isoelectric point of meat proteins and thus increases the water holding. Over time, enzymes in the meat convert longer-chain polyphosphates into diphosphate (pyrophosphate). Pyrophosphate has the ability to break actomyosin cross-bridges that have not transformed into full rigor cross-bridges. Thus, pyrophosphate is the most effective form for increasing water holding and emulsifying ability of meat proteins. However, pyrophosphate has low solubility in water and tends to settle out of brine solutions as insoluble aggregates. Thus, meat curing brines are typically prepared using longer chain, more soluble polyphosphates. Even when using more soluble phosphates, great care must be taken to assure that the phosphate goes into solution before other ingredients, especially salt, are added. For sausage products, where phosphate solubility is not an important issue, it is common to utilize phosphate blends with a higher proportion of pyrophosphate. Thus, the maximum benefit of the phosphate may be realized immediately. In addition to their influence on water binding and protein hydration, polyphosphates are also able to chelate metal ions that might otherwise catalyze lipid oxidation. Cooked meat products containing alkaline polyphosphates exhibit less lipid oxidation and flavor loss during storage than similar products without phosphate. Phosphates have also been shown to reduce microbial growth, especially that of Gram-positive bacteria. The effect is most pronounced for longer-chain polyphosphates but is also detectable for pyrophosphate.

Erythorbate Erythorbate (sodium or potassium erythorbate) is a reducing agent used in cured meat products to facilitate the reduction of nitrite to nitric oxide. Sodium erythorbate and erythorbic acid are isomers of sodium ascorbate and ascorbic acid (vitamin C), respectively. Some manufacturers prefer to use the more expensive ascorbic acid in place of erythorbate because they want to list vitamin C on the ingredient statement. As reducing agents, erythorbate, erythorbic acid, ascorbate, and ascorbic acid are chemically equivalent. Erythorbate is quite important in the curing reaction as it promotes the production of nitric oxide that binds to and stabilizes myoglobin. This is especially beneficial in products

Additives | Functional such as frankfurters that might be manufactured and cooked in a very short time, less than 2 h. Use of erythorbate is also beneficial in products such as bacon where elevated residual nitrite might lead to formation of undesirable nitrosamines. In the USA, bacon is required to have 550 mg kg−1 of sodium erythorbate or equivalent in the formulation in order to reduce residual nitrite. Because nitrite is quickly converted into nitric oxide, its concentration has to be reduced before the high temperature of frying can lead to nitrosamine production. Erythorbic acid or ascorbic acid may be used as reducing agents and oxygen scavengers to slow down light-induced fading of cured meat color. For this application, a solution is used to spray or dip the product before vacuum packaging. The application must not add appreciable weight to the product but can be quite helpful in extending the color shelf life of a cured meat product.

Sweeteners Sucrose, dextrose, and corn syrup products, among others, are commonly used as sweeteners in manufactured meat products. These carbohydrate materials are usually included to impart a desired degree of sweetness. However, properties such as surface browning, water binding, mouthfeel, or smoothness, and the ability to be fermented by microorganisms are also important considerations in choosing the right sweetener. Nonnutritive sweeteners such as saccharin, cyclamate, aspartame, and sucralose have not been widely utilized in the meat industry due to high cost and limited functional benefits. The sweetness of sugars is usually described in reference to sucrose (cane sugar). Considering sucrose to have a sweetness value of 100, the sweetness of some other sugars is as follows: fructose ¼ 173, dextrose ¼ 74, glucose ¼ 74, and lactose ¼ 16. Corn syrup and dried corn syrup products may be manufactured with a wide range of sweetness, depending on the degree of starch hydrolysis and dextrose isomerization to fructose. High fructose corn syrup with sweetness of approximately 130 is made by complete hydrolysis of corn starch to dextrose and maximal enzymatic conversion of dextrose into fructose. Low sweetness corn syrup products would be manufactured using only partial hydrolysis of corn starch to dextrose and no conversion of dextrose to fructose. Low sweetness corn syrup products are utilized more for their water-binding abilities than for sweetness. Surface browning of meat products during cooking is a desirable process involving sugars in the product. Caramelization of sugars might lead to surface browning if very high temperatures greater than 190 °C are achieved as with radiant heat cooking. However, the Maillard browning reaction between protein and a reducing sugar is much more common in meat products. Dextrose, glucose, and corn syrup sweeteners all participate in the Maillard browning reaction. However, sucrose does not participate much in Maillard browning. The use of sucrose alone may lead to insufficient surface color during cooking and smoking of meat products.

Seasonings Seasoning is the general term for ingredients used primarily to impart or modify flavor of food products. Many seasonings

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also contribute to product color. Seasonings include spices, herbs, and vegetables among others. Spices are aromatic parts of plants. The particular part may be the fruit, seed, bud, flower, stem, leaf, or root of the plant. Herbs, a subclass of spices are dried aromatic leaves. The flavor or aroma intensity of natural spices varies with season, geographic source, and cultural conditions. Thus, the flavor and aroma of seasoned meat products may vary also. To improve product consistency, many processors have chosen to use essential oils or oleoresins of spices with standardized flavor and aroma intensities. Essential oils include only the volatile, aromatic components extracted from the natural spices. They generally have little color and may not have a typical spice flavor because nonvolatile taste components are not included. Essential oils are usually extracted using steam distillation to recover the volatiles from the natural spice. Essential oils are widely used in the fragrance industry but are less common in the food industry. Oleoresins are derived from natural spices by solvent extraction. They include both volatile and nonvolatile components of the spice. Thus, their flavor and aroma might closely match that of the natural spice. The solvents selected for extraction can greatly influence the content of the oleoresin. A low-polarity solvent, such as petroleum ether, will recover a different set of components than a higher-polarity solvent, such as acetone. Solvents are generally chosen so that the oleoresin includes the principal flavor, aroma, and color components of the natural spice. Natural spices are harvested, dried, and ground with minimal heat treatment in order to protect the important volatiles present. The lack of a thermal kill step means that many bacteria, especially spore formers, survive on the ground spices. For many years, an ethylene oxide gas fumigation treatment was used to sterilize natural spices. Presently, irradiation is replacing ethylene oxide as the preferred sterilization technique. Both techniques are effective for destruction of bacteria. However, concerns with respect to dangers from small residual amounts of ethylene oxide are motivating many companies to switch to irradiation sterilization.

Flavorings The term ‘flavoring’ is usually reserved for manufactured ingredients intended to impart or strengthen a specific flavor or flavor note. Most flavorings are made from high-protein materials such as soy protein, yeast extract, milk protein, or blood serum proteins. The protein is partially hydrolyzed to produce a mix of peptides that impart a particular flavor, such as beef or pork flavor. The hydrolysis and chemical modification process used in preparation of flavorings is a highly protected art with much of the technology developed by trial and error. Flavor chemists share few of their secrets but some generalizations are wellestablished. Extensive hydrolysis to produce many short peptides tends to heighten the overall intensity, especially the bitter aspect of the flavoring. Complete hydrolysis of a protein with a high content of glutamic acid leads to production of monosodium glutamate (MSG). MSG is an effective flavor

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Additives | Functional

potentiator and activates the umami receptor to give a savory note central to meat flavor. Very mild hydrolysis leads to a flavoring with low flavor intensity. This ingredient might be used when the processor wants to take advantage of other protein properties, i.e., water holding, in addition to the flavor.

Tenderizers Tenderization of meat products can be achieved in several ways. Some of the ingredients used for tenderization include proteolytic enzymes, acids, salt, and phosphate, among others. See ‘Tenderizing mechanisms: (c) Chemical/enzymatic’ in this encyclopedia for a detailed discussion.

Antimicrobials Many of the ingredients used in meat processing, for example, salt, nitrite, and phosphate, have antimicrobial properties. Nevertheless, only a few ingredients are used primarily for their antimicrobial capabilities. These are the focus of this section. For many years, mold inhibitors were the principal class of antimicrobials used in the meat processing industry. Products in this category include potassium sorbate and propyl paraben. They are used in dry sausage manufacture to control surface mold growth. Casings for dry sausage may be dipped in a solution before stuffing, or the chubs or links may be dipped after stuffing. Recent regulatory changes, including a zero tolerance for certain pathogens, especially Listeria monocytogenes and E. coli O157:H7, have led to a greatly increased interest in antimicrobials for fresh and ready-to-eat meat products. Many new ingredients or new applications of existing ingredients are in use or under investigation. Laboratory findings often fail to hold true in the field; so some or most of today's new antimicrobial ingredients might survive the test of time. Following is a description of some of the antimicrobials of interest. Most of the recent work with antimicrobials has focused on surface sprays or dips that kill or limit growth of bacteria on fresh meat or ready-to-eat product surfaces. Organic acids, such as lactic, citric, and acetic, fall in this category along with sodium diacetate, acidified sodium chloride, acidified calcium sulfate, and cetylpyridinium chloride. Activated lactoferrin may also be used as a surface treatment to prevent bacteria from attaching to the meat surface, thus making them more susceptible to removal or destruction. Sodium or potassium lactate might also be used as antimicrobial ingredients in formulation of meat products, especially ready-to-eat items. Bacteriocins, small proteins or peptides produced by certain bacteria, are another new type of antimicrobials of interest in the meat industry. Nisin, a bacteriocin produced by the lactic acid bacteria Lactococcus lactis, is used in the food industry as an inhibitor of Gram-positive organisms. When incorporated into the casing or packaging material of a processed meat product, nisin helps control bacterial growth on the product surface. Other bacteriocins also show promise for helping control pathogens or spoilage organisms in meat products.

Antioxidants Lipid oxidation is a considerable problem for flavor of precooked meat items. On heating, physical and chemical changes take place in meat, making unsaturated fatty acids susceptible to rapid lipid oxidation. Oxidation also occurs slowly in fresh meat exposed to light and air. Initiation of oxidation may be controlled by limiting exposure to light and oxygen. The focus of this entry is control of lipid oxidation using antioxidant ingredients. Lipid oxidation includes initiation and propagation events. Antioxidants work by preventing initiation or by stopping propagation. Initiation of oxidation in meat usually involves oxygen and a metal catalyst, such as iron or copper. The first step is the metal-catalyzed production of a free radical. Antioxidants that chelate metals prevent initiation by keeping the catalysts away from the substrate. Citric acid, polyphosphates, and EDTA (ethylene diamine tetraacetic acid) prevent oxidation by chelating metal ions that might otherwise catalyze initiation of lipid oxidation. Propagation of lipid oxidation over time occurs as free radicals formed during initiation react with oxygen and move on to attack another fatty acid double bond. This attack produces a new free radical that can repeat the process. This cascade process can be stopped by providing free radical acceptors that reduce the free radicals to a nonreactive form. BHA (butylated hydroxyanisol), BHT (butylated hydroxytoluene), TBHQ (tertiary butyl hydroquinone), PG (propylgallate), alpha tocopherol (vitamin E), nitric oxide from sodium nitrite, and the natural antioxidant in the spice rosemary, all act as free-radical scavengers donating electrons to reduce the free radicals to a stable form. Lipid oxidation naturally occurs in the lipid, hydrophobic portion of meat products. Nevertheless, oxidation intermediates, such as free radicals, might be quite hydrophilic and move into the water portion of the product. Many antioxidants (BHA, BHT, PG, and tocopherols) segregate into the lipid portion whereas citric acid, polyphosphates, EDTA, and nitric oxide localize in the water portion. For best control of oxidation, it might be beneficial to include both a hydrophobic and hydrophilic antioxidant. Control of lipid oxidation in cooked meat products often involves a combination of control measures. For example, smoked ham contains polyphosphates that control initiation and nitrite (nitric oxide) that acts as a free radical acceptor. In addition, ham usually contains ascorbate or erythorbate, an oxygen scavenger, and is vacuum packaged to limit oxygen exposure. When all these measures are in place to protect against oxidation, smoked ham might be stored under refrigeration for months without appreciable loss of flavor due to lipid oxidation. The same muscle cooked as a pork roast without any added antioxidant protection would exhibit detectable off-flavor within a few hours after cooking.

Acidifiers Acidifiers are added to meat products to impart a tangy or tart flavor note, to extend shelf life, to tenderize fresh meat, or to promote protein denaturation and moisture release in dried snack products. Acidification is achieved by natural fermentation in traditional, long-process fermented sausages

Additives | Functional (Hard Salami), and some whole-muscle products (Proscuitto Ham). However, direct addition of an acidifier allows the process to proceed more rapidly, achieving the desired pH reduction in a matter of minutes. Direct acidification allows the manufacture of many products that would not be practical using natural fermentation. The most commonly used acidifiers in meat products are lactic acid and citric acid. Lactic acid is favored in products intended to compete with naturally fermented products because it has the same flavor profile. Citric acid is usually less expensive than lactic and is preferred in products such as dry sausage where its antioxidant properties are beneficial. Other acidifiers include acetic, adipic, fumaric, malic, phosphoric, and tartaric acids. Glucono-delta-lactone (GDL) is a unique acidifier sometimes used in the meat industry. It has little effect on pH until it is hydrolyzed to produce gluconic acid. This delayed acid release may be quite beneficial as discussed below. Several important properties of meat, including color, water-binding ability, and protein functionality, are influenced by pH. Thus, addition of an acidifier to a meat product might have a variety of effects, both expected and unexpected. The normal pH of postmortem muscle is 5.6–5.8. This is somewhat above the isoelectric pH of muscle proteins. With addition of acid, the pH declines toward the isoelectric point where water binding is at its minimum and protein denaturation proceeds more rapidly. Below the isoelectric pH, protein denaturation continues with loss of fresh meat color and reduced protein solubility. Acid-denatured proteins are less able to bind water, emulsify fat, or form a heat-set gel that adheres meat pieces together. The timing of acidification is often critically important in determining product properties. If acid is added at the start of the mixing process for a ground meat batter, the surface proteins on each meat particle will be denatured, causing bind failure. The finished product will be crumbly or mealy, and fat will separate during cooking. This problem may be managed by using GDL or an encapsulated acid and adding the acid very late in the mixing process. As mentioned above, GDL is acidic only after hydrolysis to gluconic acid. Encapsulated acid is similarly delayed from contact with the meat by virtue of a lipid coating around acid droplets. Encapsulated acid is not released until the cooking process when elevated temperature leads to melting of the lipid coating. At this point in the process, acid and heat denaturation of protein lead to a firm, cohesive texture.

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See also: Additives: Extenders. Chemical Analysis for Specific Components: Curing Agents. Chemical and Physical Characteristics of Meat: Protein Functionality; Water-Holding Capacity. Chemistry and Physics of Comminuted Products: Nonmeat Proteins. Curing: Brine Curing of Meat; Natural and Organic Cured Meat Products in the United States; Production Procedures. Processing Equipment: Brine Injectors. Smoking: Liquid Smoke (Smoke Condensate) Application. Tenderizing Mechanisms: Chemical; Enzymatic

Further Reading Alvarez, D., Castillo, M., Payne, F.A., et al., 2007. Prediction of meat emulsion stability using reflection photometry. Journal of Food Engineering 82, 310–315. Ashie, I.N.A., Sorensen, T.L., Nielsen, P.M., 2002. Effects of papain and a microbial enzyme on meat proteins and beef tenderness. Journal of Food Science 67, 2138–2142. Cassens, R.G., 1990. Nitrite-Cured Meat: A Food Safety Issue In Perspective. Trumbull, CT: Food & Nutrition Press Inc, 176pp. Keeton, J.T., 1983. Effects of fat and NaCl/phosphate levels on the chemical and sensory properties of pork patties. Journal of Food Science 48, 878–881. McKeith, F.K., Merkel, R.A., 1991. Technology of developing low-fat meat products. Journal of Animal Science 69, 116–124. Prabhu, G.A., Sebranek, J.G., 1997. Quality characteristics of ham formulated with modified corn starch and kappa-carrageenan. Journal of Food Science 62, 198–202. Ruusunen, M., Puolanne, E., 2005. Reducing sodium intake from meat products. Meat Science 70, 531–541. Sebranek, J.G., Bacus, J.N., 2007. Cured meat products without direct addition of nitrate or nitrite: What are the issues. Meat Science 77, 136–147. Tarte, R., 2009. Ingredients in Meat Products: Properties, Functionality and Applications. New York: Springer

Relevant Websites http://www.fao.org/docrep/010/ai407e/ai407e14.htm Food and Agriculture Organization of the United Nations, Regional Office for Asia and the Pacific, CURED MEAT CUTS. http://www.fao.org/docrep/010/ai407e/ai407e06.htm Food and Agriculture Organization of the United Nations, Regional Office for Asia and the Pacific, NON-MEAT INGREDIENTS. http://www.foodadditives.org/phosphates/q_and_a.html International Food Additives Council, Phosphates Department.

ANIMAL BREEDING AND GENETICS

Contents DNA Markers and Marker-Assisted Selection in the Genomic Era Traditional Animal Breeding

DNA Markers and Marker-Assisted Selection in the Genomic Era EA Navajas, Instituto Nacional de Investigación Agropecuaria, Canelones, Uruguay r 2014 Elsevier Ltd. All rights reserved. This article is a revision of the previous edition article by Navajas and Simm, volume 1, pp 19–27, © 2004, Elsevier Ltd.

Glossary Breeding value Sum of average effects of alleles, summed over the pair of alleles at each locus and over all loci affecting a trait. It is traditionally predicted based on the performance of the individual and relatives for the trait. Genomic breeding value Prediction of the genetic merit of the animal based on information provided by high density panels of DNA markers (genomic information). Genomic selection Selection is based on breeding values predicted from a very large number of estimated DNA marker effects across the whole genome. It is also a marker assisted selection because genomic data is combined with other sources of information to enhance accuracy of breeding values at an early age and facilitate the selection of new traits. Marker-assisted selection (MAS) The process of using information provided by DNA-markers to predict the

Introduction Most economically relevant traits in livestock production systems are under genetic control, which implies that they can be genetically improved by exploiting the genetic variability within and between breeds. Significant genetic improvement rates have been reported in many characteristics such as growth performance, wool production, and milk composition. Less emphasis has been given in selection schemes in livestock species to those attributes which are related to carcass composition, meat quality in particular. This is partially explained by the difficulties and high costs of measuring them. However, more attention has lately been given by breeders and geneticists to carcass and meat quality traits due to the stronger influence that consumer satisfaction has had on the supply chain in the past few decades; consequently, increased

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genetic merit, assisting the identification of the best animals to be used as parents of the next generation. The DNA marker information should contribute to improve the accuracy of selection and increase the rate of genetic progress by identifying animals carrying desirable genetic variants for a given trait at an earlier age. Molecular marker Identified segment of the DNA in the genome with known sequence and location on a chromosome. Nowadays, single-nucleotide polymorphisms (SNPs) are commonly used markers in association studies and genomic selection. Quantitative trait Phenotypes (characteristics) that vary in degree and can be attributed to polygenic effects and their environment. Quantitative trait loci (QTL) Chromosome segments containing or linked to the genes that underlie quantitative traits.

efforts are being directed toward the genetic improvement of carcass traits and meat quality. Advances in molecular genetics are leading to valuable applications in the meat industries, such as providing accurate paternity tests or certifying the origin of specific products. The limitations of identifying superior genotypes for meat quality, due to the difficulties of collecting phenotypic data on these traits, may be overcome by molecular genetics. The very recent developments in structural and functional genomics, as novel and promising techniques, will provide a more comprehensive understanding of the genetics and metabolic paths, with direct application on genetic improvement. This article presents main concepts on deoxyribonucleic acid (DNA) markers and markerassisted selection with emphasis on carcass and meat quality. The potential of the novel genomic tools and their implications for the genetic improvement of these traits are discussed.

Encyclopedia of Meat Sciences, Volume 1

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Animal Breeding and Genetics | DNA Markers and Marker-Assisted Selection in the Genomic Era

Role of Molecular Markers on Genetic Improvement of Carcass and Meat Quality Traits Most of the relevant carcass and meat quality characteristics are quantitative traits whose phenotypic expression is the result of the joint action of several genes and environment. In general, the evaluation of the genetic merit of individuals and breeds is based on the analysis of phenotypic records plus pedigree information. Although phenotypes are not perfect predictors of breeding values, conventional animal breeding methodologies have been effective in the genetic improvement of traits under selection. The limitation on obtaining phenotypic information of carcass and meat quality is a significant restriction for their genetic improvement, especially for meat quality. Modern in vivo noninvasive techniques allow the inclusion of carcass composition in the selection schemes using measurements on breeding animals, but the assessment or prediction of meat quality traits still relies on the implementation of siblings or progeny tests, which lead to longer generation intervals and, consequently, slower genetic progress. The inclusion of the genetic information provided by molecular markers can make a significant contribution to the genetic improvement of carcass and meat quality traits. Estimations of genetic merit can be available for breeding animals at younger ages with levels of accuracies that were not possible before. Higher selection accuracies and shorter generation intervals will lead to higher rates of genetic improvement. In addition, it would be possible to consider in breeding programs some very difficult and expensive traits to measure, such as fatty acid composition or flavor. Furthermore, it will be possible to investigate the differential expression of genes in different muscles and different in vivo and postmortem phases, by the application of transcriptomics and proteomics. Based on the information provided by the transcriptome and the proteome, these new ‘omics’ give insight into the genes being expressed and the proteins influencing metabolic pathways, thus complementing the understanding achieved through genomics.

Markers and Quantitative Trait Loci Genetic variability at DNA level can be directly assessed by using genetic markers. They are segments of DNA with a known position in the genome, which can be identified by laboratory tests (genotyping). By analyzing DNA samples that are very easy to extract from tissue samples, such as hair, blood, or meat, the variant (allele) of each genetic marker which an animal carries can be detected. Markers are of different types. In the recent past, markers called microsatellites were the ones of preference because they were very polymorphic (many alleles) and, therefore, highly informative. However, the genotyping of this type of marker is relatively expensive and difficult to standardize. Nowadays, single nucleotide polymorphisms (SNP) are extensively used. They are abundant and the genotyping shows low rate of errors at a low cost with current technologies. In some cases, the marker is the gene of interest, or it is a fragment of DNA within the gene. If this is the case, knowledge of the marker variant directly indicates which the gene's variant (direct marker) is (Figure 1).

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However, in most cases, genetic markers are nonfunctional or neutral genes, which are linked to the gene of interest (indirect marker). Despite being nonfunctional, indirect genetic markers can provide valuable information not only for the identification of the target gene but also for selection on the trait of interest. Direct and indirect genetic markers can be used in genetic improvement schemes, although they require different strategies and lead to different responses to marker-assisted breeding, which will be discussed in the Section Identification of QTL and Genes. Genetic markers have become strategic tools for the identification of loci underlying the expression of quantitative traits, known as quantitative trait loci (QTL). Methodologies used in genetic evaluations are based on the assumption that quantitative characteristics are controlled by an infinite number of genes, each with infinitesimal (very small) effect. Nevertheless, genes or QTL with moderate effects have been identified. In general, important progress has been made in the identification and location of QTL affecting traits that are economically relevant for livestock production systems, including carcass and meat quality attributes. Information on QTL identified in cattle, sheep, pigs, and chickens are available on online databases with free access (AnimalQTLdatabases www.animalgenome.org/ QTLdb). Other very useful public databases on genes and markers are also available (i.e., GenBank, www.ncbi.nlm.nih. gov/genbank; FunctSNP, www.csiro.au/science/FunctSNP).

QTL and Genes Affecting Carcass and Meat Quality Quality is a complex concept that is a function of several traits that vary according to the species and target markets. Table 1 presents some carcass and meat characteristics for which significant QTL have been identified, whereas Table 2 summarizes significant findings for muscularity and tenderness, which are major carcass and meat quality traits, respectively. Tenderness has been defined as one of the most important eating quality traits for consumer. Important efforts have been dedicated to unravel the genetic background of this attribute. The genes responsible for µ-calpain (CAPN1) and calpastatin (CAST) with effects on meat tenderness have been identified and SNP markers associated with them have been reported. The role of the calpain/calpastatin system on tenderness is described in other article. Although independent validations have confirmed the effect of these markers, their effects need to be validated in different commercial populations, because of differences in genetic frequencies in Bos indicus and Bos taurus breeds and the likely interaction between these genes. Muscle development and shape in the carcass are relevant to define value in terms of actual meat yield or conformation and muscularity. The Myostatin (GDF8) gene has been associated with double-muscling phenotypes in some European breeds of cattle, such as Belgian Blue, Charolais, and Piedmontese, and with improved muscularity in sheep. The larger muscle development is due to an increased protein synthesis translated into a higher number of muscle fibers (hyperplasia). In the case of this gene, in most of the studies, neutral or favorable effects on meat tenderness were reported.

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Animal Breeding and Genetics | DNA Markers and Marker-Assisted Selection in the Genomic Era

Direct marker Target gene

Indirect marker

M

M

H

Marker D = distance = 0 cM

D>0

Possible marker-gene combinations M

H

M

M m

L

m

H

m

L

M

Recombinants

Inferences on genotype with Marker genotype Direct marker

MM

HH

Mm

HL

mm

LL

Total

100%

Indirect marker (D=10 cM) HH HL LL

(20.7%) (4.1%) (0.2%)

HH

(4.1%)

HL LH LL

(41.3%) (0.4%) (4.1%)

HH HL LL

(0.2%) (4.1%) (20.7%) 83%

Figure 1 Direct and indirect genetic markers. When a direct marker is available for the gene of interest, the marker variants indicate precisely the allele of the target gene. The genotypes for the genes of interest can be inferred directly from the marker genotypes. In this example, the marker alleles M and m are associated with the high (H) and low (L) performance alleles, respectively. Therefore, an MM genotype in a direct marker indicates accurately that the animal is homozygous for the favorable allele (HH), whereas Mn and mm imply that the genotypes for the gene of interest are HL and LL, respectively. An indirect marker is located close to the gene, but it is not the gene itself. The distance D between marker and gene will determine the magnitude of the linkage. It is considered that M and H and m and L are linked. However, recombination events can lead to new combinations of marker and gene alleles (M–L and m–H). Owing to these possible combinations between marker and target alleles, it cannot be surely told that which marker allele is associated with the gene variants, and thus the confidence in the inference from marker genotypes is lower. Considering D ¼10 cM, 83% of our inferences are correct, but in 17% cases, marker genotypes indicate the wrong allele is the gene of interest. Obtaining markers closer to the target genes will reduce this uncertainty because recombination rates are lower.

In sheep, the Callipyge gene (CLPG) has a pronounced effect on hindquarter muscularity. Characterization of Callipyge lambs indicates greater dressing percentages and heavier and leaner carcasses than in normal lambs. However, the gene also has a severe detrimental effect on tenderness of high-value muscles. The increased toughness of Callipyge meat has been explained

by a reduced rate and extent of postmortem proteolysis that results from increased levels of calpastatin. Carwell is another gene in sheep that increases muscle development, but its effect is limited to the longissimus muscle. Although it may have a mild unfavorable effect on tenderness, this is not commercially relevant and can be removed by postmortem treatment.

Animal Breeding and Genetics | DNA Markers and Marker-Assisted Selection in the Genomic Era

Identification of QTL and Genes The traditional approach used to map QTL in livestock species is termed as genome scan. In previous approaches, markers were selected to cover the whole genome with an average distance of 20 cM between them. An extensive list of major DNA-marker trials in farm livestock developed in the 1990s is Table 1 Carcass and meat quality characteristics for which significant QTL have been found

Carcass quality

Meat quality

Beef cattle

Pigs

Carcass weight Dressing percentage Predicted saleable beef yield Eye muscle area Rump (P8) fat depth Marbling score

Carcass length Dressing percentage Proportion of lean Fatness Backfat Ultimate pH Color Water-holding capacity Intramuscular fat

Tenderness

Table 3 Species

15

presented in Table 3. The identification of QTL is based on the combined analysis of molecular and phenotypic information by searching for significant associations under specific experimental designs. One common design in farm animals was to map QTL segregating in crosses based on parental populations that are highly divergent for the traits of interest. Figure 2 shows the general concept that underlies the identification of QTL linked to genetic markers. Although QTL experiments provided very valuable information, only few QTL with moderate or larger effect were Table 2

Some major genes affecting carcass and meat quality

Trait

Name

Specie

Chromosome

Locus

Muscularity

Callipyge Carwell Myostatin

18 18 2

– – GDF8

Tenderness

m-Calpain Calpastatina

Sheep Sheep Cattle Sheep Cattle Cattle

29 7

CAPN1 CAST

Genome scans searching for QTL affecting meat and/or carcass attributes Population

Research group

Country

Pigs

Large White × Pietrain Meishan × Large white Pietrain × (Meishan or wild boar) Meishan × Large white Landrace × Iberian breed Wild boar × Large white Meishan × Large white Chinese breeds × Yorkshire Berkshire × Yorkshire Meishan × Large white Meishan × Synthetic line

Liège University INRA Hohenheim University Agricultural University of Norway IRTA–INIA University of Uppsala Roslin Institute Iowa State University Iowa State University University of Minnesota USDA

Belgium France Germany Norway Spain Sweden United Kingdom USA USA USA USA

Beef cattleb

Charolais × Brahman Limousin × Jersey Angus × Brahman (Brahman × Angus) × MARC III (Brahman × Herford) × MARC III (Piedmontese × Angus) × MARC III Belgian blue × Marc III

Cooperative Research Centre AgResearch – Adelaide University Texas A&M US Meat Animal Research Centre US Meat Animal Research Centre US Meat Animal Research Centre US Meat Animal Research Centre

Australia New Zealand – Australia USA USA USA USA USA

Sheepc

Texel × Coopworth

AgResearch, Sydney University, Adelaide University Sydney University INRA AgResearch Roslin Institute, Univeristy of Edinburgh, and Scottish Agicultural College Roslin Institute USDA Clay Centre USDA Clay Centre

Australia – New Zealand

a

Awassi × Merino INRA401 Fat and lean selection lines Texel, Suffolk, and Charollais commercial sire reference animals Scottish Blackface lean and fat selection lines Rambouillet × Romanov Suffolk × Romanov a

Australia France New Zealand United Kingdom United Kingdom USA USA

Bidanel, J.P., Rothschild, M., 2002. Current status of quantitative trait locus mapping in pigs. Pig News and Information 23, 39N−53N. Burrow, H.M., Moore, S.S., Johnston, D.J., Barendse, W., Bindon, B.M., 2001. Quantitative and molecular genetic influences on properties of beef: A review. Australian Journal of Experimental Agriculture 41, 893−919. c Crawford, A.M., 2001. A review of QTL experiments in sheep. Proceedings of the 14th Conference of the Association for the Advancement of Animal Breeding and Genetics, pp. 33−38. Queenstown: Association for the Advancement of Animal Breeding and Genetics. Abbreviations: INRA, Institut National de la Recherche Agronomique; IRTA−INIA, Institut de Recerca i Tecnologia Agroalimentàries−Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria; USDA, United States Department of Agriculture. b

16

Animal Breeding and Genetics | DNA Markers and Marker-Assisted Selection in the Genomic Era

Divergent breeds

×

Breed J

Breed L

M

M

m

m

Q

Q

q

q

First cross:

L×J

Back cross:

(L × J)L

M

m

Q

q

M

Q

M

q

m

Q

m

q

m

q

m

q

m

q

m

q

Molecular information

‘Mm’

‘mm’

Phenotypic information

Mean ‘Mm’ Comparison of means:

If ‘Mm’

‘mm’:

If ‘Mm’ = ‘mm’:

Mean ‘mm’

marker-QTL association NO marker-QTL association

Figure 2 Searching for QTL–genetic marker associations in a backcross design between two breeds. Breeds L and J are two divergent breeds, which are assumed as homozygous for different alleles of both QTL (Q, q) and genetic marker (M, m). F1 animals are heterozygous for the marker and linked QTL. Backcrossed animals are obtained by mating F1 crosses to L individuals. There are four classes of gametes formed by the F1: the parental gametes MQ and mq and the recombinant gametes Mq and mQ. Because parental breeds are homozygous, L gametes are all mq. The resulting segregation in the backcross may allow the identification of the QTL. Genotyping provides the information of marker genotypes and phenotypic recording supplies data on the trait of interest. If the average of the Mm individuals is significantly different from the average of those with mm genotype, it is then concluded that the QTL affecting the trait of interest is linked to the genetic marker.

detected and mapped, given the power of the QTL experiments. In addition, further studies were needed before incorporating QTL into breeding programs to confirm that QTL mapped in crosses between divergent breeds or in a different breed were relevant to the genetic variation within the target breeding population. The size of the effects of an identified QTL is needed to be reestimated in commercial populations because they may differ between genetic backgrounds, environments, or production systems. Fine mapping of QTL was used to reduce the broad chromosomal region derived from genome scans. Additional markers in the flanking region were tested in QTL linkage studies, thus improving the precision of QTL location. Furthermore, the fine-mapping approach has the potential of narrowing down the number of candidate genes and eventually identifying the causative polymorphism. A candidate gene

is a known gene in another species that is related to the physiology underlying the trait of interest. After the candidate gene is chosen, the association between polymorphism/alleles for that gene and the phenotypic expression of the trait is investigated. It is important to mention that the assistance provided by genetic markers in terms of genetic improvement does not necessarily require the identification of the causative genes. Nevertheless, the detection of the gene and the development of direct marker tests were expected to lead to a more effective utilization of DNA technology in genetic improvement. Only a few commercial DNA tests are available for economically relevant traits, although many of them are related to carcass or meat quality traits. Examples for beef tenderness are the DNA tests Pfizer GeneSTAR® and Ingenity TenderGENE®, which include the CAPN1 and CAST genes. In sheep,

Animal Breeding and Genetics | DNA Markers and Marker-Assisted Selection in the Genomic Era LoinMAX® and MyoMAX® provide information for carcass quality based on the Carwell and Myostatin gene, respectively. In addition to these tests, there are new tools which can take into account simultaneously the information captured by hundreds or thousands of markers after their calibration using training populations. These genomic tools are explained later in this article. Despite considerable efforts in QTL mapping and application of marker-assisted selection, the incorporation of DNA markers into the breeding programs has been low and the general impact poor. Under the QTL mapping approach previously described, marker densities were insufficient to find markers that were linked with QTL at the population level (population-wide linkage disequilibrium). Owing to the low marker densities, QTL of minor effect were not detected or their effects were overestimated, leading to inconsistent results across QTL mapping studies and reinforcing the relevance of carrying out independent validations studies before utilization in breeding programs. Validation studies of commercial DNA tests for economically relevant traits showed that effects were not necessarily similar in all populations. On the basis of phenotypic data and DNA samples from reference cattle populations, a very interesting initiative was put in place by the US National Beef Cattle Evaluation Consortium (NBCEC) to independently verify the associations claimed by commercial genotyping companies. The results are in the public domain and can be found in the NBCEC web page.

Genomic Selection Recent developments in DNA technology and genome sequencing have led to the detection of thousands of SNPs, making possible a very dense coverage of the genome, at affordable genotyping costs. Dense arrays of SNPs (SNP chip) have been developed for many livestock species that are commercially available (Table 4). The availability of genome-wide dense markers has allowed the implementation of genomic selection in which the estimation of the genetic merit is assisted by the information provided by thousands of markers. Based on this methodology, and because of the high density of markers used, every QTL would be in population-wide linkage disequilibrium and all QTL affecting any trait would be considered simultaneously, independently of the magnitude of QTL effects. The implementation of genomic selection can be defined in two steps. In the first step, the SNP effects are estimated in a training population that comprises animals with genomic data as well as with information on the relevant traits. The second step is to use the estimated effects of the SNP to predict the genetic merit of the breeding animals. Using genomic information, it is possible to estimate genetic merit just with the information obtained from a DNA sample, for very young animals. This information allows making earlier selection decisions that will reduce the generation interval. It may also increase the number of animals with information of their merit, which will have a positive effect on selection intensity.

Table 4

17

SNP Beadchips available for cattle, pigs, and sheep

Specie Product name

Number of SNP Company

Cattle

BovineSNP50K 54 001 Bovine3K 2 900 BovineLD 6 090 BovineHD 777 962 Axiom Genome–Wide BOS 1 Array 648 855 Pigs PorcineSNP60 62 163 Sheep OvineSNP50 54 241

Pedigree information Productive data

Training populations

Illumina Illumina Illumina Illumina Affymetrix Illumina Illumina

‘Traditional’ breeding value Enhanced breeding value

Genomic breeding value

Figure 3 Combining genomic information in breeding programs. Breeding values are predicted on the basis of phenotypic (performance records) and pedigree data. The enhanced breeding values result from adding the genomic breeding values. The estimation of genomic breeding values relies on the genomic information of the animals and the SNP effects. The analysis of the genomic and phenotypic data of training populations provides the magnitude of the SNP effects.

In practice, genomic information is integrated to the genetic evaluation engines in addition to pedigree and phenotypic data, which are the ‘traditional’ sources of information to predict the genetic merits. The flow of information is illustrated in Figure 3. The higher accuracies in this case due to more precise relationships will also contribute to obtain higher rates of genetic progress. Genetic evaluations including genomic information are already in place in many dairy cattle, pig, and poultry breeding programs. Regarding beef cattle breeds, the American Angus Association, using SNP data, is publishing estimations of genetic merit (www.angus.org/Nce/WeeklyEvalGenomicData. aspx), whereas other breeds such as Hereford are developing their training populations in the context of their international genetic evaluation program, which involves USA, Canada, Uruguay and Argentina Hereford data simultaneously (www. hereford.org/static/files/0711Genomics.pdf). Genomic breeding values are also now available in the sheep genetic programs run by Sheep Improvement Limited in New Zealand (www.sil. co.nz/News/Sheep50k-breeding-values-available.aspx). In contrast with marker-assisted selection, genomic selection does not require a QTL detection step, as all markers, either significant or not, are considered. In fact, a one-step methodology to estimate enhanced breeding values (traditional plus genomic breeding values) is being implemented in some dairy cattle and in pig breeding programs. Nevertheless, the improvement of accuracy due to the genomic information can be enhanced by ensuring that markers linked to relevant QTL are present in the SNP chip being used.

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Animal Breeding and Genetics | DNA Markers and Marker-Assisted Selection in the Genomic Era

Genome-Wide Association Studies and Functional Genomics The information provided by the high density SNP chips enables not only the implementation of genomic selection but also genome-wide association studies that provide very valuable information for the identification of specific polymorphism with favorable effects on carcass and meat quality. Fine mapping, however, may not be sufficient to achieve this objective. A more comprehensive understanding is possible by combining the information provided by functional genomic tools to high-density genotyping or DNA genome sequencing data. Gene expression/transcriptomic profiling can give new insights to the actual SNP with influence on the traits of interest. The contribution of proteomics to meat quality is discussed in other article. For both genomic selection and genome-wide association studies, the size of the training population and the quality of the data being recorded are of relevance. The volume of carcass and meat quality information with genomic data have a direct association with the accuracy of genomic breeding values and, therefore, on the additional genetic progress to be achieved. Similarly, the power of the genome-wide association studies will be stronger, and more accurate findings will be obtained. In this sense, the availability of accurate, less expensive, and time consuming methods to assess carcass and meat quality will make a significant contribution. New methods such as near-infrared spectroscopy and video-image analysis for the prediction of carcass and meat quality, respectively, will be useful sources of data to be collected directly in abattoirs in large number of animals. A comprehensive characterization of meat and carcass quality attributes using more expensive and laborious evaluation methods will be always very valuable, particularly as part of more detailed studies exploiting the potential of all new genomic tools.

See also: Animal Breeding and Genetics: Traditional Animal Breeding. Chemical and Physical Characteristics of Meat: Palatability. Classification of Carcasses: Beef Carcass

Classification and Grading. Conversion of Muscle to Meat: Aging. Meat Marketing: Market Requirements and Specifications. Proteomic Technologies and Their Applications in the Meat Industry

Further Reading Aguilar, I., Misztal, I., Johnson, D.L., et al., 2010. A unified approach to utilize phenotypic, full pedigree, and genomic information for genetic evaluation of Holstein final score. Journal of Dairy Science 93, 743–752. Barendse, W., 2009. Genetic-based diagnostic tools for predicting meat quality. In: Kerry, J.P., Ledward, D.A. (Eds.), Improving the Sensory and Nutritional Quality of Fresh Meat, first ed. Cambridge: CRC Press, pp. 292–317. Barendse, W., 2011. Haplotype analysis improved evidence for candidate genes for intramuscular fat percentage from a genome wide association study of cattle. PLoS ONE 6, e29601. doi:10.1371/journal.pone.0029601. Bishop, S.C., Karamichou, E., 2009. Genetic and genomic approaches to improving sheep meat quality. In: Kerry, J.P., Ledward, D.A. (Eds.), Improving the Sensory and Nutritional Quality of Fresh Meat, first ed. Cambridge: CRC Press, pp. 249–263. Dekkers, J.C.M., 2004. Commercial application of marker- and gene-assisted selection in livestock: Strategies and lessons. Journal of Animal Science 82 (E-supplement), E313–E328. Falconer, D.S., Mackay, T.F.C., 1996. Introduction to Quantitative Genetics, fourth ed. Harlow, UK: Longman. Hayes, B.J., 2007. QTL Mapping, MAS, and Genomic Selection. A Short-Course Organized by Animal Breeding & Genetics Department of Animal Science. Iowa State University. 4−8 June 2007. Available at: http://www.ans.iastate.edu/section/ abg/shortcourse/notes.pdf (accessed 06.10.13). Meuwissen, T.H.E., Hayes, B.J., Goddard, M.E., 2001. Prediction of total genetic value using genome-wide dense marker maps. Genetics 157, 1819–1829. Mullen, A.M., Pannier, L., Hamill, R., 2009. New insights into the biology of meat quality from genomic and proteomic perspectives, with particular emphasis on beef. In: Kerry, J.P., Ledward, D.A. (Eds.), Improving the Sensory and Nutritional Quality of Fresh Meat, first ed. Cambridge: CRC Press, pp. 199–224. Rothschild, M.F., Hu, Z.L., Jiang, Z., 2007. Advances in QTL mapping in pigs. International Journal of Biological Science 3, 192–197. Schefers, J.M., Weigel, K.A., 2012. Genomic selection in dairy cattle: Integration of DNA testing into breeding programs. Animal Frontiers 2, 4–9. doi:10.2527/ af.2011-0032. Van Eenennaam, A.L., Li, J., Thallman, R.M., et al., 2007. Validation of commercial DNA tests for quantitative beef quality traits. Journal of Animal Science 85, 891–900.

Traditional Animal Breeding N Lambe and G Simm, Scotland’s Rural College, Edinburgh, UK r 2014 Elsevier Ltd. All rights reserved. This article is a revision of the previous edition article by Lambe and Simm, volume 1, pp 11–19, © 2004, Elsevier Ltd.

Glossary Best linear unbiased prediction A statistical procedure for predicting the breeding values of animals. Estimated breeding value (EBV) An estimate of an individual's true breeding value (genetic merit) for a trait, based on the performance of the individual and its relatives for the trait, and for genetically correlated traits. Expected progeny difference It is EBV divided by two. The difference in expected performance of future progeny of an

Introduction Meat production can be influenced to a large extent by animal breeding and genetics. Several breeding strategies that can affect carcass composition and meat quality will be reviewed in this article, that include (1) selection between breeds within species; (2) crossbreeding to combine desirable characteristics from more than one breed or strain, or to exploit heterosis in crossbred progeny; and (3) genetic selection of superior breeding stock within a breed. Genetic influences on carcass and meat quality and selection programs designed to improve these traits will also be discussed.

Differences among Breeds When selecting among breeds within a species, it is important to choose a breed that is able to perform well within the relevant environment as well as meet the appropriate market demands. Differences among breeds are only relevant in the environments in which they have been measured, because of possible genotype by environmental interactions. Most breed comparisons of carcass composition and meat quality have been performed in temperate climates, using animals on a high level of nutrition. Studies performed in more extreme environments (e.g., tropical or subtropical), or when food is less abundant, have been fewer in number and have shown less convincing evidence of breed differences. It is also of note that any breed comparison is a snapshot in time, as breeds evolve as a result of selection, so results from breed comparisons may change over time.

Carcass Composition Large between-breed differences exist within all farm animal species for growth and carcass composition traits. As an animal matures, it undergoes an increase in the ratio of muscle to bone, followed by a decrease in muscle growth rate and an

Encyclopedia of Meat Sciences, Volume 1

individual, compared with expected performance of future progeny of an individual of average genetic merit. Heterosis Advantage of crossbred progeny over the average performance of the individual parent breeds. Intermuscular fat It is defined as the fat deposited between muscles. Intramuscular fat It is the fat deposited within muscles. Subcutaneous fat It is defined as the fat deposited under the skin.

increase in the ratio of fat to muscle. However, breeds vary in their rate of maturation and average mature weight. Therefore, standardizing measurements of body composition (proportions of muscle, fat, and bone) to the same stage of maturity of body weight (ratio of actual weight to expected mature weight) results in much less variation in carcass composition than standardizing to the same age or weight. One exception to this rule is the Texel breed of sheep, which shows less total body fat than expected for its mature size (Table 1). In beef cattle, late-maturing breeds, such as the Continental European breeds, are often preferred under conditions of good nutrition, producing heavier carcasses with little fat. Earlymaturing beef breeds, such as the traditional British breeds (e.g., Angus, Hereford, and Shorthorn), can be harvested at lighter weights and may be preferred for grass-based systems, when food supply is limited or for certain markets such as those rewarding higher intramuscular fat. Similarly, in lamb production systems, the use of early-maturing breeds (e.g., Southdown) will allow faster finishing of small lambs with good carcass composition. However, the use of larger breeds that mature later (e.g., modern Suffolk strains) will result in heavier lambs with less fat. Traditionally, early-maturing pig breeds (e.g., Middle White) were used for pork production and late-maturing breeds (e.g., Large White) for bacon production. Strains and hybrids of improved pig breeds that are now used in pork and bacon production (e.g., Piétrain, Landrace, Table 1 species

Heritability ranges for carcass composition traits across

Trait

Heritabilitya

Ultrasound muscle depth/area Ultrasound fat depth Carcass weight Carcass length Dressing percentage Lean yield Lean:bone ratio

Moderate–high Moderate–high Moderate–high High Low–moderate Moderate–high Moderate–high

Low¼ 0−0.25; moderate ¼ 0.25−0.5; and high ¼0.5−1.

a

doi:10.1016/B978-0-12-384731-7.00001-5

19

20

Animal Breeding and Genetics | Traditional Animal Breeding

Hampshire, and Large White) have better carcass composition than that of traditional British pig breeds (e.g., Tamworth, Gloucester Old Spot, and Saddleback), owing to reduced fat levels and increased muscle percentage. Breeds may partition fat and muscle differently between body depots. Dairy breeds of sheep and cattle have a higher proportion of body fat in internal depots than meat breeds, which have higher proportions of subcutaneous fat. In general, maternal sheep breeds that have higher reproductive rates and higher levels of milk production also have increased proportions of noncarcass fat. During growth and development, intermuscular fat is deposited before subcutaneous fat, which is deposited before intramuscular fat. Therefore, relative to subcutaneous fat, large late-maturing cattle breeds have a higher proportion of intermuscular fat than small earlymaturing breeds, which have increased levels of intramuscular fat (e.g., British beef breeds vs. Continental European breeds). Breed comparisons in pigs have found that the Duroc, Meishan, and Berkshire breeds have a high proportion of intramuscular fat compared with other improved breeds, and for some markets, the level of intramuscular fat in pure Duroc and Berkshire pigs is too high for consumer acceptability.

Meat Quality In addition to yield and carcass composition, meat quality is determined by traits such as color and composition of muscle and fat, level of intramuscular fat, juiciness, tenderness and texture, and flavor and aroma. Objective laboratory-based techniques that are discussed in other articles have been developed to quantify many of these traits. These measurements are often referred to as technological traits and some examples are listed in Table 2. The most widely used of these techniques is ‘shear force,’ which measures the force required to cut through samples of cooked meat. Trained sensory panel analysis is still considered the most relevant measure for many meat quality traits and Table 2 also gives examples of some of these sensory traits. There is substantial evidence of betweenbreed variation in technological and sensory meat quality traits. Examples include the following: • Paler, more watery muscle, with more exudation of fluids during storage, in ‘improved’ pig breeds compared with traditional British pig breeds (e.g., Pietrain vs. Bekshire). • Yellower fat in Channel Island cattle breeds compared with other cattle breeds. • More tender, fine-grained meat in smaller breeds of cattle, owing to smaller muscle bundles. • More tender meat in ‘double-muscled’ Piedmontese cattle compared with some other breeds. • More tender meat in Bos taurus cattle breeds than in Bos indicus (humped cattle) breeds. Bos indicus cattle show increased calpastatin activity in the muscle, which is known to inhibit postmortem tenderization. • More tender meat in Duroc pigs compared with most other breeds, owing to an increased amount of red muscle fibres and increased intramuscular fat. • Increased flavor, juiciness, and tenderness in pigs with an increased percentage of Duroc, Berkshire, or Meishan genes.

Table 2

Heritability ranges for meat quality traits across species

Trait

Heritabilitya Technological (objective)

Color Lean color Fat color Lean color reflectance Myoglobin content Juiciness Water-holding capacity Drip loss Tenderness Lean texture/firmness Shear force Calpastatin activity Myofibrillar fragmentation index Intramuscular fat content Marbling score Chemical intramuscular fat % Ultimate pH Flavor Overall acceptability

Sensory (subjective)

Low–moderate Low Low–moderate Moderate–high Low Low Low–moderate Low–moderate Low–moderate Moderate–high Moderate–high Moderate–high

Moderate–high Moderate–high Low–moderate Low Low

Low¼ 0−0.25; moderate ¼ 0.25−0.5; and high ¼0.5−1.

a

Breeds can also react differently to on-farm management, transport, preslaughter, slaughter, and processing methods. For example, leaner and lighter animals are more likely to suffer from cold shortening in the carcass post-mortem.

Crossbreeding Crossbreeding can be used for several reasons that can be exploited simultaneously. One reason may be to combine desirable characteristics from more than one breed or strain. This is termed ‘complementarity.’ In the pig and poultry industries, different breeds or specialized lines, selected for different characteristics, are commonly crossed to produce commercial hybrids. Sire lines are often selected to be heavier and faster growing, whereas female lines may be selected for reproductive traits, low maintenance requirements, or other economically important factors. An example of such a system for pigs is given in Figure 1. The breeds or strains chosen for crossing depend on their suitability for specific environments as well as market requirements. Crosses between different breeds of sheep and cattle are also used to combine desired characteristics. In the United Kingdom, hill ewes (e.g., Scottish Blackface and Swaledale) are often crossed to rams from upland breeds (e.g., Blue-faced Leicester and Border Leicester) with high maternal performance. The crossbred female progeny are then mated to terminal sire breeds (e.g., Texel, Suffolk, and Down breeds) that have been selected for improved carcass and growth traits, to produce a high number of better-quality lambs. Another reason for crossbreeding is to exploit heterosis, or hybrid vigor (advantage over the average performance of the

Animal Breeding and Genetics | Traditional Animal Breeding

Nucleus breeding herds

Multiplication herds

Large white (selected for maternal traits)

Landrace (selected for maternal traits)

Piétrain (selected for lean yield)

Pure-bred male parent

Cross-bred female parent

Commercial herds

21

Commercial growing pig

Figure 1 Example of a pig breeding program.

individual parent breeds). Heterosis is widely exploited in the pig, beef cattle, and poultry industries. The ‘combining ability’ of different strains is tested to increase production. Some strains combine well only when used as the male or the female parent. The pure-bred lines that are used for crossing can be either selected to improve specific traits within line (e.g., meat yield and fertility) or selected on the performance of their crossbred progeny (reciprocal recurrent selection). Heterosis is usually greater for traits with low heritability (see Section Genetic Parameters for Carcass Composition and Meat Quality Traits), such as those affecting overall fitness, reproduction, or survival, and less for production or carcass traits. Some evidence suggests that cross-bred cattle mature more quickly and are thus heavier at a given age, with more marbling fat, total fat, and muscle. However, after adjusting for weight, heterosis for carcass composition traits tends to be low. Effects of heterosis on most technological and sensory meat quality traits have not been studied widely, but available estimates tend to be low for juiciness, tenderness, flavor, cooked color, and overall desirability. Results for the effect of heterosis on shear force in beef are more widely reported and range from slightly unfavorable to moderately favorable.

Differences within Breeds Substantial genetic improvement can be made within breeds for desired characteristics. This method relies on the fact that the traits to be improved are heritable, and that more animals are produced than need to be kept for replacement stock, to allow selection among progeny for preferred breeding animals.

Genetic Parameters for Carcass Composition and Meat Quality Traits Heritability is the proportion of the total phenotypic (observed) variation in a trait that is explained by genetic variation. It is, therefore, a measure of how much a trait is

controlled by genes (or, more precisely, genes that act additively), as opposed to environmental influences. Heritability is expressed on a scale of 0 to 1, where a value of 1 suggests that the trait is completely controlled by an animal's genes, and management, feeding, and other environmental factors play no part in determining the expression of the trait. Traits with higher heritability allow a higher rate of genetic improvement than traits with low heritability. Estimates of heritabilities for the main carcass and meat quality traits vary between studies but tend to fall in the ranges identified in Tables 1 and 2. There is a good agreement across species for heritability estimates of these traits. Relatively few studies have been conducted on genetic parameters of eating quality traits compared with carcass composition. However, in general, the heritability of most carcass composition traits is moderately high, and objective technological measures of meat quality are more heritable than sensory traits determined by sensory panel analysis. Selection responses in sensory meat quality traits are, therefore, expected to be low because they are less heritable and more difficult to evaluate. It is important to note that the magnitude of the environmental variation and, therefore, the heritability depends very much on the ability to standardize measurements. The better the meat quality traits are measured, the higher their heritability and the higher the selection success. A low heritability does not necessarily mean that there is too little genetic variance for selection; rather, it may reflect the difficulties in measuring the traits in a standardized, repeatable, and accurate manner. Genetic parameters for meat quality may also differ according to the type of muscle tested within an animal and owing to differences in preslaughter conditions (e.g., stress during transport or at the abattoir) or processing methods (e.g., electrical stimulation, conditioning, and hanging method). For example, shear force has been reported to be more variable in carcasses that have not undergone electrical stimulation. In particular, genetic parameters for meat tenderness vary, probably because this is a very complex trait, depending on many factors (pH and temperature changes postmortem, glycolysis, and processing) and the interactions among them.

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Animal Breeding and Genetics | Traditional Animal Breeding

Selection on one trait will often lead to correlated responses in other traits, which are not always monitored but could have very important economic consequences. A selection program designed to improve carcass composition should also be concerned with the effects of these changes on sensory meat quality traits and should monitor effects on reproductive traits (e.g., fertility and dystocia) and functional fitness. There are concerns that selection for reduced fat levels may be associated with reduced fertility of females and it may delay puberty, as observed, for example, in pigs and cattle. Genetic improvements in pig and poultry production have also been related to a decrease in meat quality in terms of flavor and texture. In general, intramuscular fat percentage has a negative genetic relationship with meat yield and a positive genetic relationship with total fat. Intramuscular fat in pigs was ignored in early studies, as its importance for eating quality was underestimated. As pigs were selected for reduced back fat, the level of intramuscular fat was also reduced, which was later linked to a reported decline in the eating quality of pig meat. Attempts are now under way in some countries to increase intramuscular fat in pig meat without increasing total fat. Studies in some sheep and cattle populations suggest that this may be possible, as low to moderate genetic correlations have been found between levels of fat in different depots. There is also evidence in pigs that different fat depots are at least partially under different genetic control. This may allow selection in these species to reduce one fat depot (e.g., subcutaneous), whereas maintaining moderate levels of fat in other depots, to reduce or avoid the unintended consequences mentioned, or to maintain marbling and meat quality (intramuscular fat). Correlations among carcass composition and technological and sensory meat quality traits differ among studies, as a result of which few strong trends have emerged. In general, the literature suggests that selecting for leanness might have slight negative effects on eating quality traits (e.g., water-holding capacity, tenderness, juiciness, pH, and drip loss). Sensory quality traits such as tenderness, flavor intensity, and juiciness tend to be positively correlated to one another, and genetic correlations between these traits and shear force tend to be negative (lower shear force equals more tender). Shear force also has a low to moderate negative genetic correlation with intramuscular fat. Tenderness is widely thought to be the most important determinant of meat quality to consumers. However, genetic parameters for this trait differ, depending on the muscle tested and the method of measurement (myofibrillar fragmentation index, calpastatin activity at 24 h, shear force, or sensory panel assessment of tenderness). The majority of results suggest that calpastatin activity is highly genetically correlated with shear force (higher calpastatin activity ¼ higher shear force), but the phenotypic correlation between the two measurements is only moderate. Correlations of tenderness among different muscles are moderately low and the correlation between shear force and sensory panel evaluation of tenderness also varies between muscles. As a result, selection for tenderness may be difficult and further work is needed to determine the relationships between technological and sensory measurements. (At least in beef, and the research at KState, the correlation between trained sensory panel tenderness and Warner-Bratzler shear force (WBSF) is high and negative.)

(There are animals that defy the antagonisms between carcass composition and meat quality. For example, the expected progeny differences (EPDs) of an American Simmental bull at ABS global (a company specialising in bovine genetics and reproduction), which has a global rank in the top 5% for marbling, in the top 5% for longissimus muscle area, and in the top 5% for WBSF. In other words, using this bull can simultaneously increase muscling, increase marbling, and decrease WBSF in progeny.)

Selection Programs In genetic improvement programs, animals are selected on their own performance, on the performance of their relatives, or on a combination of both. First, the breeding goal or goals – i.e., the traits to be improved – must be decided and subsequently the selection criteria determined. The latter are the measurements that will be taken and then selected on in order to improve the breeding goal. In some cases, the breeding goals and the selection criteria are the same, but often they are not, especially with carcass and meat quality traits. Traits to be used as selection criteria must be highly repeatable and practical to measure on-farm or online during animal processing. Selection criteria should be heritable and should show sufficient variation within the population. The design of the breeding program should define the number of male and female animals that are to be selected each year, the age at mating, the generation interval, and other such factors. Genetic selection programs differ in complexity. A relatively simple approach is to select breeding animals on the basis of their own phenotypic performance (e.g., ultrasound data obtained from selection candidates). However, the impossibility of collecting actual phenotypic carcass and meat quality data on selection candidates has restricted the use of this method of selection for many of these traits. ‘Independent culling levels’ in one or more traits are often used to improve the genetic merit of the flock or herd. This method involves choosing animals for breeding only if they reach a certain threshold in each trait of interest (e.g., over a certain weaning weight and/or below a certain ultrasound fat depth). Using a selection index is a more complicated, but effective, method of selecting animals on more than one trait, based on the performance of the individual and its relatives. This method allows selection of traits that can be measured directly or indirectly (using predictor traits) on the selection candidates themselves and also traits that can only be measured on relatives (e.g., slaughter and meat quality traits). Accurate recording of performance data and pedigree structure is vital in these programs. The amount of emphasis or weighting on each trait in a multitrait index can be altered and is usually determined by economic importance. Estimated breeding values (EBVs) for each trait for each animal are produced, and then are combined into an overall ‘index score.’ Selection decisions are based on these index scores. Response to selection in any individual trait per generation using a multitrait index is smaller than what could be achieved by selecting for that trait alone. However, index selection will lead to the highest rate of change in overall economic merit.

Animal Breeding and Genetics | Traditional Animal Breeding EBVs are calculated, in most selection programs, using a statistical procedure known as best linear unbiased prediction (BLUP). This procedure predicts the genetic effects for each trait separately from management and environmental influences. The EBV is determined by the genetic merit of the animal itself, plus that of its relatives, for the trait of interest and reflects the genetic or breeding merit of that animal compared with the population mean. Because, on average, each breeding animal passes half of its genes to its offspring, the breeding value for each trait is often expressed as the expected progeny difference (EPD), which is half the EBV of the breeding animal. If the breeding goal of a selection program is to improve carcass composition, the selection criteria will often include predictors of composition taken on the live animal. As live weight is a composite trait (meat, fat, and bone), it is usually not a sufficient predictor of carcass composition. However, carcass composition can be estimated in vivo using techniques such as mechanical and optical probes, ultrasound scanning, or computed tomography (CT) scanning. Ultrasound is commonly used in selection programs for sheep, cattle, and pigs to measure depths and areas of subcutaneous fat and muscle (Figure 2) and greatly improves the predictions of body composition above those estimated from live weight alone. In cattle and pigs, intramuscular fat has also been estimated using ultrasound measurements taken on live animals. CT scanning increases the accuracy of predictions of total carcass fat, muscle, and bone compared with ultrasound and allows the measurement of tissues in different body depots and regions (Figure 3). Measurements of average muscle density resulting from CT scanning can also provide moderate predictions of intramuscular fat levels in live sheep and pigs. Two-stage selection can be carried out in sheep and pig

Ischium Hip

23

populations, where ultrasound scanning is used on-farm to screen large numbers of selection candidates, and then a small number of top-ranking animals are CT scanned to make final selection decisions based on conformation or composition of breeding stock. Because there are few live-animal predictors of technological and sensory meat quality traits, breeding programs designed to improve meat quality use mainly measurements taken on slaughtered relatives of selection candidates to calculate EPDs (or EBVs depending on the scale used) for these traits. For example, most cattle breed associations in the United States now produce EPDs for marbling and a few have published EPDs for tenderness measured by shear force. Similar traits are included in some cattle breeding programs in the UK and Australia.

Figure 2 Example of an ultrasound scan taken in beef cattle.

Ischium

Hip

LV5 LV2 TV8 LV5

LV2

White = bone Light grey = muscle Dark grey = fat TV8 Figure 3 Example of CT scan images from a sheep. LV, lumba vertebra; TV, thoracic vertebra.

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Animal Breeding and Genetics | Traditional Animal Breeding

In many countries, a relatively low proportion of beef cattle and sheep are performance recorded and, therefore, are included in genetic improvement programs. In these industries, there are many small-scale breeders and although abattoirs usually provide some financial incentives to improve conformation and reduce fat levels, few incentives are given to improve other aspects of eating quality. However, a few countries are now trying to implement grading systems that also reward for improved meat quality traits such as marbling levels, pH, and color (e.g., Meat Standards Australia). There has been considerable genetic progress in lamb and beef carcass composition due to selection programs. In several countries (e.g., United States, Canada, and Europe), ‘central testing’ has been used to identify sheep or cattle of superior genetic merit, where high-ranking individuals from different farms are tested together at a central station to reduce environmental

variation and allow the measurement of ‘difficult to measure’ traits. There is some concern over the effectiveness of this approach, especially if animals are submitted at later ages, and the use of this method seems now to have decreased. Its importance could, however, increase if genome-wide selection methods are employed. ‘Progeny testing’ can also identify superior breeding animals by recording data on progeny of highranking animals, either at a central testing station or on-farm. This method allows carcass and meat quality traits to be measured directly on progeny of breeding stock. However, central and progeny testing are time consuming and expensive and are only likely to be used to select sires for use in widespread artificial insemination programs. Group breeding and sire reference schemes are now being used by sheep and beef breeders in several countries. Group breeding schemes usually involve a nucleus breeding flock or herd of elite animals taken

Flock A

Flock E

Flock B

Reference sires

Flock C

Flock D

Key

= Progeny of reference sires

= Progeny of other rams

Figure 4 Schematic diagram of a sire referencing scheme (see plate 1). Reproduced from Simm, G., Wray, N.R., 1991. Sheep Sire Referencing Schemes – New Opportunities for Pedigree Breeders and Lamb Producers. SAC Technical Note T264. Edinburgh: SAC.

Animal Breeding and Genetics | Traditional Animal Breeding from different group member farms. This nucleus undergoes intensive recording and selection in order to produce breeding animals (usually males) of high genetic merit so that they can be used on breeders' farms. More popular now are sire reference schemes, in which all flocks or herds are linked by the use of common sires on a proportion of females on each farm (Figure 4). These schemes use BLUP on data from all farms to produce EPDs (or EBVs) that are comparable across all member flocks or herds. Breeding populations in pig and poultry production are controlled mainly by relatively few large national or international breeding companies. In these industries, ‘production pyramids’ exist, where intensive selection takes place in the elite breeding herds or flocks. The resulting animals, of superior genetic merit, are multiplied in number and usually crossed to produce commercial animals for meat production (Figure 1). All tiers of the industry are therefore influenced by improved genetics in the top breeding herds or flocks. High selection intensities, short generation intervals, and reduced environmental influences on production in these species maximize the output of high-quality product. As a result of this structure, there have been industry-wide improvements in growth rate, uniformity, muscle yield, feed conversion efficiency, and fat levels in both pigs and poultry.

Major Genes Most production traits are continuous in their distribution and are controlled by the action of many genes, each having a

Table 3

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small effect. These are termed polygenic or quantitative traits. However, some traits are substantially influenced by a single major gene or quantitative trait locus. Some major genes are known to have large effects on carcass composition and meat quality traits in the populations in which they are found. Examples are given in Table 3. Phenotypic records from relatives can be monitored to detect the presence of major genes and identify individuals and families with the desired genotypes. The use of molecular techniques to identify animals with different genotypes will allow much greater exploitation of these major genes or other genes with smaller, but important, effects. More advanced molecular and reproductive techniques, such as cloning and genetic modification of livestock species, may also play important roles in the meat industry in future.

Future Considerations Traditionally, the aim of selection was to increase production efficiency and lean yield in farm animals raised for meat production. However, recent consumer preferences for healthy and convenient meat products produced in welfare-friendly systems call for different breeding goals and selection traits. Future selection objectives are likely to incorporate more meat quality issues. Genetic variation has been blamed for an inconsistent product. However, genetic variation provides the opportunity to increase meat quality within livestock populations. The potential to improve meat quality by traditional breeding methods would be greatly increased by the

Examples of major genes affecting carcass composition and meat quality

Major gene/Quantitative trait locus (QTL)

Species: Breed

Effects on carcass and meat quality

Dwarfism Myostatin gene (‘double muscling’)

Poultry Cattle: Belgian Blue, Piedmontese, and other breeds Sheep: Texel and other breeds

Diacylglycerol acyltransferase 1 (DGAT1) Calpain gene (CAPN1) Calpastatin gene (CAST) Callipyge

Cattle Sheep Cattle Cattle Sheep: Poll Dorset originally

Reduces: growth rate; mature weight Reduces: subcutaneous fat; marbling; collagen content; lean color intensity; and flavor. Increases: muscularity; muscle: bone ratio; muscle:fat ratio; eye muscle area; dressing percentage; and water content Affects intramuscular fat; marbling; and tenderness (sheep)

Carwell (Loin-Max)

Sheep: Poll Dorset originally

Texel Muscling QTL (TM-QTL)

Sheep: Texel

Ryanodine receptor 1, ‘halothane gene’ (RYR1) PRKAG3 (new alleles of the ‘RN’gene)

Pigs

Fatty acid-binding protein (FABP) genes IGF2 gene

Pigs: Hampshire Pigs: Meishan originally Poultry Pigs Cattle

Affects tenderness Affects tenderness Reduces: carcass fat; marbling; and tenderness. Increases: muscularity; lean yield; dressing percentage; and connective tissue content Increases: lean yield; eye muscle depth. Reduces: tenderness slightly, but this effect can be eliminated by enhanced processing Increases: loin muscling. Reduces: tenderness slightly, but this effect can be eliminated by enhanced processing Reduces: ultimate pH; water-holding capacity. Increases: pale, soft, exudative (PSE) meat; meat quality variation Reduces: processed meat yield; ultimate pH; lean color intensity. Increases: drip loss; variation in meat quality Affects intramuscular fat and fat deposition Affects weight of primal cuts, lean meat yield, backfat thickness, and eye muscle area

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Animal Breeding and Genetics | Traditional Animal Breeding

development of tools to measure or predict meat quality in vivo. The incorporation of such measures into large-scale, organized breeding programs would allow direct selection for meat quality traits.

See also: Chemical and Physical Characteristics of Meat: Adipose Tissue; Color and Pigment; Palatability; pH Measurement; Water-Holding Capacity. Species of Meat Animals: Meat Animals, Origin and Domestication

Further Reading Burrow, H.M., Moore, S.S., Johnston, D.J., Barendse, W., Bindon, B.M., 2001. Quantitative and molecular genetic influences on properties of beef: A review. Australian Journal of Experimental Agriculture 41, 893–919. Falconer, D.S., Mackay, T.F.C., 1996. Introduction to Quantitative Genetics, fourth ed. Harlow: Longman. Lawrie, R.A., 1998. Lawrie's Meat Science, sixth ed. Cambridge: Woodhead Publishing.

Macfarlane, J.M., Simm, G., 2008. The contribution of genetic improvement for lamb meat production. Proceedings of the 3rd International Symposium about Goat and Sheep Meat Type − 3rd Sincorte, Tecnol. & Cien̂ . Agropec., João Pessoa, v.2, n.3, pp. 7–14. Marshall, D.M., 1999. Genetics of meat quality. In: Fries, R., Ruvinsky, A. (Eds.), The Genetics of Cattle. Wallingford: CAB International, pp. 605–636. Sellier, P., 1998. Genetics of meat and carcass traits. In: Rothschild, M.F., Ruvinsky, A. (Eds.), The Genetics of the Pig. Wallingford: CAB International, pp. 464–495. Simm, G., 1998. Genetic Improvement of Cattle and Sheep. Tonbridge: Farming Press. Simm, G., Wray, N.R., 1991. Sheep Sire Referencing Schemes − New Opportunities for Pedigree Breeders and Lamb Producers. SAC technical note T264. Edinburgh: SAC. Thompson, J.M., Ball, A.J., 1997. Genetics of meat quality. In: Piper, L., Ruvinsky, A. (Eds.), The Genetics of Sheep. Wallingford: CAB International, pp. 523–538. de Vries, A.G., Faucitano, L., Sosnicki, A., Plastow, G.S., 2000. Influence of genetics on pork quality. In: Wenk C., Fernández J.A., Dupuis M. (Eds.) Quality of Meat and Fat in Pigs as Affected by Genetics and Nutrition, pp. 27−35. Proceedings of the joint session of the EAAP commissions on pig production, animal genetics and animal nutrition, Zurich, August 1999. The Netherlands: Wageningen Academic publishers. Wilson, D.E., 1992. Application of ultrasound for genetic improvement. Journal of Animal Science 70, 973–983.

ANIMAL HEALTH RISK ANALYSIS

SP Cobb and SC MacDiarmid, Ministry for Primary Industries, Wellington, New Zealand r 2014 Elsevier Ltd. All rights reserved. This article is a revision of the previous edition article by SC MacDiarmid, EJ Thompson, volume 1, pp 27–31, © 2004, Elsevier Ltd.

Glossary Hazard identification A process of identifying pathogenic agents that might be associated with the commodity considered in a risk analysis. Risk A function of the likelihood of an event occurring and the likely magnitude of the biological and economic consequences of that event. Risk analysis A science-based process composed of hazard identification, risk assessment, risk management, and risk communication. Risk assessment A process to evaluate the likelihood and biological and economic consequences due to the entry, establishment, and spread of a pathogen in an importing country.

Introduction The international trade in animals and animal products presents a degree of risk to the importing country because of the possible presence in the commodity of pathogens that might threaten the resources (human, animal, or environmental) of the importing country, although this risk should not be used as an unjustifiable barrier to trade. Animal health import risk analysis is a tool that provides an objective and defensible method of identifying and managing disease risks associated with the importation of animals, animal products, animal genetic material, feedstuffs, biological products, and pathological material. Risk is defined as a function of the likelihood of a disease entering a country and the likely consequences of the disease affecting other animals. Import risk analysis provides a systematic approach to the identification of hazards (pathogens) that might be associated with an imported commodity, assessment of the likelihood and consequences of introducing diseases, formulating sanitary measures to manage this risk, and communicating the findings to others.

Risk communication The exchange of information, opinions, and results with potentially affected and interested parties during a risk analysis. Risk management A process to identify, select, and implement measures to reduce identified risks. Sanitary measures Measures applied to imported goods that protect animal or human health or life in the importing country from risks associated with the entry, establishment, or spread of a pathogen. Uncertainty A lack of knowledge about a parameter being assessed. Uncertainty can often be reduced by further studies or surveys. Variability The effect of natural chance on a parameter. Unlike uncertainty, variability cannot be reduced by further studies or surveys.

data, assumptions, methods, results, discussion, and conclusions) is essential. Without transparency, the distinction between facts and the analyst’s value judgments might blur.

Uncertainty and Variability Incomplete knowledge or a lack of understanding of a pathogen will result in uncertainty, which is likely to be present in any risk analysis. This must be distinguished from the natural heterogeneity inherent in any biological system that will result in variability in a risk pathway. If significant uncertainty is encountered when conducting a risk analysis, a precautionary approach to managing risk may be considered. However, sanitary measures selected must be based on a risk analysis that takes into account available scientific information and any precautionary measures should be reviewed as soon as additional information becomes available. A transparent rationale should always be presented to support selected sanitary measures.

Qualitative and Quantitative Methods Transparency Although import risk analysis is based on science, the process must accommodate knowledge gaps and uncertainty. Because of this, transparency (the comprehensive documentation of all

Encyclopedia of Meat Sciences, Volume 1

Qualitative risk assessments express likelihood estimates in nonnumerical terms such as high, medium, low, or negligible. This approach is suitable for the majority of risk assessments, and is routinely used for decision making. In some situations, a

doi:10.1016/B978-0-12-384731-7.00163-X

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Animal Health Risk Analysis

quantitative approach might be considered desirable as an adjunct to a qualitative assessment. Quantitative assessments express their inputs and outputs (results) numerically, but are not in themselves any more objective or precise than a qualitative approach. Quantitative models also present significant challenges in interpreting and communicating their results. Regardless of which approach is chosen, it is essential that the analysis is transparently documented and subjected to peer review.

International Obligations Under the World Trade Organization (WTO) Agreement on the Application of Sanitary and Phytosanitary Measures (SPS Agreement), members can employ sanitary measures to imported commodities but these measures must not be applied arbitrarily, or result in discrimination between members where similar conditions prevail, or constitute a disguised restriction on trade. The SPS Agreement requires WTO members to base their sanitary measures on international standards, guidelines, and recommendations, where they exist. The SPS Agreement recognizes the World Organisation for Animal Health (OIE) as the international organization responsible for the development and promotion of international standards, guidelines, and recommendations for animal health and zoonoses. However, members may choose to adopt measures that result in a higher level of protection than that provided by international standards, although these must be based on the outcome of an import risk analysis. The OIE’s Terrestrial Animal Health Code provides recommendations and principles for conducting transparent, objective, and defensible risk analyses for international trade. The four components of risk analysis described by the OIE are hazard identification, risk assessment, risk management, and risk communication.

and are transmitted by bite to a vertebrate host, need not be considered in a risk analysis for fresh or frozen meat or meat products. The methods of production, manufacturing, or processing might also exclude certain categories of pathogenic agents. Provided details of these production methods and a verifiable quality control program, which includes testing, are included as part of a commodity description, these pathogenic agents do not need to be considered individually in a risk analysis. Where categories of pathogenic agents are excluded, a description of the category and the justification for their exclusion should be included as part of the hazard identification process. For example, provided meat and meat products have been derived from animals that have been subject to antemortem and postmortem inspection in slaughter and processing plants, which operate effective Good Manufacturing Process (GMP) and Hazard Analysis and Critical Control Point (HACCP) programs, then parasites restricted to the intestinal tract do not need to be considered as potential hazards in these commodities. If hazard identification fails to identify any potential hazards associated with the imported commodity, then the risk analysis can be concluded at this point. If the importing country adopts international standards recommended in the OIE Terrestrial Animal Health Code, then there is also no need to continue a risk analysis beyond this point.

Risk Assessment Risk assessment is the evaluation of the likelihood and consequences of an exotic pathogen being introduced into the importing country. A risk assessment consists of four interrelated steps:

• •

Hazard Identification To effectively manage the risks associated with imported commodities, any organisms that could potentially cause harm and could be introduced into the importing country must be identified. The potential hazards identified are those associated with the species being imported, or from which the commodity is derived, and which might be present in the exporting country. It is then necessary to identify whether each potential hazard is already present in the importing country, and whether it is subject to control or eradication in the importing country and to ensure that import measures are not more trade restrictive than those applied within the importing country. Hazard identification also needs to consider whether strains of a potential hazard found in the importing country are likely to be less virulent than those reported internationally or in the exporting country, or if the proposed import will increase the exposure to a potential hazard in the importing country. Depending on the nature of the commodity or the degree of processing, some categories of pathogenic agents may be excluded from consideration. For example, arboviruses such as West Nile virus, which replicate in bloodsucking arthropods

• •

Entry assessment: How likely is the imported commodity to be contaminated with the hazard, leading to its introduction into the importing country? Exposure assessment: What risk pathways exist that could lead to exposure of animals and humans in the importing country to the hazard, and how likely are they to occur? Consequence assessment: What would be the consequences of exposure to the hazard? Risk estimation: A combination of the results from the entry, exposure, and consequence assessment to summarize if the identified hazard presents a risk.

It is important to note that all of the above steps might not be necessary in all risk assessments. If the likelihood of entry is negligible for a potential hazard, then the risk estimate is automatically negligible and the remaining steps of the risk assessment need not be carried out. The same situation arises where the likelihood of entry is nonnegligible but the exposure assessment concludes that the likelihood of exposure to susceptible species in the importing country is negligible, or where both entry and exposure are nonnegligible but the consequences of introduction are concluded to be negligible.

Entry Assessment Entry assessment consists of describing the biological pathway(s) necessary for an importation activity to introduce

Animal Health Risk Analysis

pathogenic agents into a particular environment, and estimating the probability of that complete process occurring. The entry assessment describes the probability of the ‘entry’ of each of the potential hazards under each specified set of conditions with respect to amounts and timing, and how these might change as a result of various actions, events, or measures. For meat and meat products to act as a vehicle for the introduction of pathogens, the agent must be able to:

• • •

Infect the species from which the commodity is derived from Disseminate to those tissues likely to be present in the traded commodity Persist in those tissues during the processing and handling conditions to which the commodity is likely to be subject.

•

•

•

The following are examples of factors that might need to be considered in an entry assessment for the importation of meat and meat products:

Biological factors

•

•

•

•

•

•

The influence of age, breed, and sex of animals on the susceptibility to the potential hazard. For example, only Muscovy ducks and their hybrids are susceptible to Derzsy’s disease so the likelihood of entry for this disease is negligible for meat commodities derived from other duck species. Means of transmission (horizontal or vertical) of the potential hazard. For example, provided OIE guidelines on breeding flock hygiene are followed, of the OIE-listed avian diseases, only highly pathogenic avian influenza (HPAI), Newcastle disease, and avian mycoplasmosis have a nonnegligible likelihood of entry in poultry hatching eggs. Infectivity, virulence, and stability of the potential hazard. Chlamydia psittaci is an obligate intracellular organism that depends on living host cells for high-energy metabolites, so will not be viable in meat. Routes of infection (oral, respiratory, etc). Inoculation of ducks with Riemerella anatipestifer via the intravenous or subcutaneous routes results in significant mortality at all challenge doses, whereas very high doses are needed to cause harm by oral challenge. Agent predilection sites. Studies have shown that low pathogenicity avian influenza (LPAI) cannot be transmitted to susceptible birds by feeding meat derived from an infected bird because virus replication is largely limited to the respiratory tract. LPAI has a negligible likelihood of entry in imported poultry meat. In contrast, HPAI replicates in a much wider range of tissues and feeding meat from an infected bird is known to transmit virus to a susceptible bird. Impact of vaccination, testing, treatment, and quarantine. Vaccination against some diseases, such as leptospirosis, might reduce the excretion rate of the organism and, therefore, the contamination of the environment. Vaccination of poultry has been shown to prevent HPAI virus replication in skeletal muscles.

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infected. For such information to have value, it should be derived from statistically based surveys reporting the disease prevalence, not just the clinical disease. Evaluation of veterinary services, surveillance and control programs, and zoning systems of the exporting country. The quality of information relating to the disease status of a country reflects the standard of veterinary services and the programs they manage. Existence of disease-free zones and compartments. If surveillance and disease management procedures allow recognition of such areas, then importation from these reduces the risk associated with that organism. Farming and husbandry practices. Traceability is recognized as an important food safety issue. Ruminants reared totally on pasture are exposed to risk factors different from those of ruminants spending part of their time housed or confined and fed concentrates. The likelihood of animals in the United Kingdom in the 1980s being exposed to the bovine spongiform encephalopathy agent depended on whether they had been fed meat and bone meal.

Commodity factors

• •

•

•

Risk increases with increasing volume of trade. Likelihood of contamination. Only healthy animals should be presented for harvest and the distance traveled before harvest should be minimized. Quality control techniques such as GMP and HACCP will help minimize contamination at harvest. The recovery of Salmonella GallinarumPullorum from poultry meat has only been reported in environments with poor hygiene practices. Effect of processing. The pH of meat drops with rigor mortis. If the pH of meat falls below 6.0, then foot-andmouth disease virus (FMDV) is likely to be inactivated. However, the pH might not fall below 6.0 if an individual is stressed prior to harvest and, as a result, FMDV may persist in the carcass. However, even in healthy animals, the pH will not fall below 6.0 in lymph nodes, blood clots, viscera, and bone marrow, so these tissues pose a risk for the introduction of FMDV. Effect of storage and transport. Freezing is recognized to inactivate a number of pathogens such as Aujeszky’s disease virus, leptospires, and hydatids. Heat treatment can also be relied on to inactivate a number of pathogens although a few, such as infectious bursal disease virus, are recognized as being able to withstand domestic cooking temperatures.

Several of these factors might be influential in determining the likelihood of a potential hazard entering a country through an imported commodity. Figure 1 illustrates how these factors might impact the likelihood of introducing porcine reproductive and respiratory syndrome virus (PRRSv) in imported pig meat.

Exposure Assessment Country factors

•

Incidence and prevalence. The incidence rate of a disease agent affects the probability of a harvested animal being

Exposure assessment consists of describing the biological pathway(s) necessary for exposure of animals and humans in the importing country to the hazards (in this case the

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Animal Health Risk Analysis

Biological factors Country factors • Age (the concentration of virus in the blood of piglets is much higher than in slaughter-age pigs. Younger pigs are also more likely to be viraemic) • Means of transmission (international spread mainly by movement of live animals and semen) • Predilection site – PRRSv replicates mainly in macrophages of the lung, lymph nodes, tonsils, and spleen

• Herd incidence and prevalence • Country freedom, for example, Sweden, New Zealand

PRRSv present in pig meat when it enters the importing country • Expected volume of trade from countries with PRRSv • Contamination of meat (160 °C)

Figure 2 Illustration of temperature profiles in roasts cooked at low and high temperatures.

Heating elements

Heating elements

Thermal conduction in air Thermal conduction in meat Thermal radiation Figure 3 Illustration of heat transfer to a roast when cooked in an oven.

cooking in liquid (stewing or boiling) or cooking at a low temperature for a long time, is recommended. Dry heat methods, such as roasting, broiling, and panfrying, are used for cooking muscles with a low content of connective tissue.

Roasting In roasting, transfer of heat is accomplished by a combination of conduction, convection, and radiation (Figure 3). The heat is transmitted to meat by normal or forced air convection (highvelocity air) in a closed oven, often preheated. Large meat pieces are placed on a rack in a roasting pan for even circulation of heat around meat. Normally, meat is not covered and is not

turned during cooking. The rate of heat transfer in an oven depends on temperature and air velocity; a forced air convection oven produces a faster temperature rise than a conventional oven. Oven roasting can apply the temperature in two different ways: a constant oven cooking temperature at approximately 150–160 1C or roasting at a high temperature of up to 250 1C followed by a lower temperature of approximately 150 1C until the required core temperature is obtained. The use of the constant oven temperature of 150–160 1C throughout the cooking period results in lower cooking loss compared with a high starting temperature. The constant temperature method also ensures that the surface of meat becomes brown due to the Maillard reaction; this method is recommended for tender meat

Cooking of Meat | Cooking of Meat with a low content of connective tissue. If the cooking condition is changed to a combination of convection and steam, the method can be used for less tender meat.

Broiling Broiling is a dry heat method in which meat is cooked using direct radiant heat. The heat source may be an oven broiler, an electric broiler, or an outdoor grill, with the meat placed either above or below the heat source. The heat radiates from one direction, so meat must be turned during cooking. The method is used for cuts with a low content of connective tissue, such as steaks, chops, and patties. The cooking time is short.

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in a pan and covered with water. Normally, the meat is not prebrowned. As the heat exchange medium is water, the maximum temperature reached is not higher than 100 1C. The method is used for meat with low as well as high content of connective tissue. If cooking is prolonged, meat with high connective tissue content will become tender because the collagen dissolves. Meat reaches the final endpoint temperature faster when cooked in water than when cooked in air of equal temperature, because the specific heat of water is higher than that of air. For experimental and research purposes, cooking in a regulated water bath is often used. Small meat samples are sealed in plastic bags and immersed in the water bath with a set temperature below 100 1C.

Low-Temperature Cooking

Microwave Cooking

Low-temperature cooking uses a constant oven cooking temperature below 100 1C, resulting in a very slow heating profile. The meat is placed in the oven as for the roasting method. Compared with normal oven roasting at 150–160 1C, the cooking time is two to three times longer, and because of the low temperature, minimal Maillard reactions occur on the surface and the appearance is like that of boiled meat. Prebrowning is, therefore, recommended to improve appearance. This method is useful for meat with a high content of connective tissue or for cuts of meat containing different muscles that differ in collagen content. ‘Prime rib’ is prepared by cooking at a low temperature for more than 8 h. The method can be combined with steam and is often used by the catering sector and for institutional food service.

Microwave cooking is a very popular method, especially for defrosting and reheating precooked meat. The principle of microwave cooking is conversion of electromagnetic energy into thermal energy within meat. During cooking, microwave energy is absorbed by rotation of water molecules and translation of ionic components in meat; the water content and the dissolved ion content are, therefore, important factors. In practice, meat is placed in a container suitable for microwave cooking, covered with a film wrap or a suitable lid, and then cooked in the microwave oven. Cooking time depends on the cooking rate, i.e., the power output (watts). Total cooking time can be decreased by one-third to one-half of that in conventional cooking in an oven. Weight of meat mass, shape, composition, and temperature before cooking are factors that influence the duration of microwave cooking. A problem with microwave cooking is that the surface of the meat does not brown because no Maillard reactions occur owing to the relatively low meat surface temperature and the low temperature of the surrounding air. If the microwave oven is supplemented with another heat source, such as convection, browning of the surface occurs. Other methods used for browning of the surface include the use of a special browning dish or a special metallic film that is responsible for some of the microwave energy being absorbed and converted into heat. Another problem with microwave cooking is uneven heating; for this reason the method is not recommended for meat with a high content of connective tissue, because the tenderizing effect of converting collagen into gelatin is not achievable within the short cooking time. Compared with conventional cooking methods, microwave cooking often results in a greater cooking loss and decreased tenderness, but this depends on the microwave setting (power output).

Pan Broiling/Panfrying Pan broiling and panfrying are methods by which small, thin cuts, such as chops, steaks, or patties, are cooked by direct heat conduction. Heat is transmitted by contact between the pan and the meat. Meat is placed in a preheated, uncovered frying pan and cooked with or without added fat. The meat should be turned frequently. The cooking time is relatively short because of the high frying temperature, and the meat surface becomes brown because of the Maillard reaction. This quick method is not recommended for meat with high connective tissue content because the tenderizing effect of converting collagen into gelatin cannot be accomplished. This is a method commonly used by consumers.

Braising/Casseroling These are moist cooking methods, especially used for meat with a high content of connective tissue where maximum tenderization is required. The meat is often prebrowned and then placed in a covered pan to which some liquid, often a small amount of water, is added. The meat is cooked slowly in the moist atmosphere, and the maximum temperature reached is not higher than 100 1C.

Boiling/Stewing/Water Bath These are methods of cooking in liquid and therefore constitute moist cooking methods like braising. The meat is placed

Sous Vide The sous vide method for preparation of meat was introduced in the 1970s. It is used for industrial production of meat or meals for the food service industry or for consumers through retail sale. The meat is vacuum packed and cooked at a temperature o100 1C using precisely controlled heating and then rapidly cooled. The meat is reheated after a period of chilled storage. The advantage of using vacuum packaging before cooking is the prevention of evaporative losses during cooking

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and elimination of oxidation during storage. Owing to the low temperature, the sous vide method has a positive effect on tenderness compared with conventional oven cooking and results in an easily controlled and uniform doneness of meat. Sous vide cooking reduces vegetative bacteria to a safe level in a combination of time and temperature. Extended cooking time increases collagen solubility.

Other Cooking Methods Belt Grill Cooking With belt grilling, meat is cooked by conduction on both sides simultaneously. Heat transmission is affected by contact between meat and heat source. Meat is conveyed between preheated plates or belts without added fat and does not have to be turned. The cooking time is relatively short owing to the high temperature.

Clamshell Grilling A clamshell grill is a cheaper domestic cooker using the same principle as a belt grill cooker.

Temperature Control and Timetable When cooking meat, it is important to control the core temperature or the endpoint temperature to achieve the ideal degree of doneness. A timetable is only a guideline for an approximate cooking time. Variation in cooking time depends on cooking method, cooking equipment, size, and shape of the meat cut as well as fat and bone content. Boneless meat cooks more quickly than meat with bones. It is important that control of the core temperature in the meat is precise. This means inserting the thermocouple of the thermometer into the geometric center of the meat without touching either bone or fat. With low-temperature cooking, it is easier to measure the internal temperature exactly because of the slow rise of temperature rise in meat (Figure 2).

Resting Period after Cooking When the meat has been cooked and removed from the heating medium, the core temperature continues to increase, because the cooking process goes on inside meat. The final endpoint temperature after the resting period depends on the cooking method, the cooking temperature, and whether or not the meat is covered with foil. In general, the higher the temperature of the heating medium, the larger is the residual heat and the higher is the final temperature after resting. Postcooking temperature rise is greater for microwave cooking. The resting period is often 15–30 min. The reason for recommending a resting period, as described in many cookery books, is that the juice in the meat can redistribute and the meat remains juicy after being cut into slices. However, a recent study has reported that pork and beef remain juicy even when being cut into slices immediately after cooking.

Effects of Cooking Methods on the Eating Quality of Meat It is well known that different cooking methods, core temperatures, and types of muscles result in different eating qualities. Three main factors differ depending on cooking method: the temperature at the surface of meat, the temperature profile through meat, and the method of heat transfer. The temperature at the surface is important for the color, odor, and flavor of meat. Temperature gradient influences the rate and extent of the changes of protein structure in the meat, whereas the method of heat transfer influences the odor, flavor, and color. In general, optimal tenderness and juiciness and minimum cooking loss in meat are achieved when it is cooked at moderate to low temperatures. With respect to odor and flavor, higher temperatures yield different flavor perceptions compared with low cooking temperatures. Numerous studies have indicated a poorer eating quality in meat with increasing internal temperature.

Effect of Cooking on Color The color of meat is a combination of the amount of myoglobin and the reflectance of protein. Raw meat has a bright pink or red color that depends on the nature and composition of meat (see Changes in Meat during Heating). Color is influenced by heat treatment (cooking method) and endpoint temperature. Increase in endpoint temperature increases the brown color and decreases the pink color. Dry heat methods, especially panfrying, influence the surface color: a brownish color is achieved compared with the moist heating methods where no browning effect is seen.

Effect of Cooking on Odor and Flavor Flavor is a combination of taste and aroma. Taste is a sensation related to the tongue, whereas aroma is a sensation of volatile compounds related to the epithelia of the nose. Flavor comprises a combination of nonvolatile and volatile compounds. Odor and flavor of raw meat are bland, weak, and blood like. When meat is heated, several odors and flavors are produced through heat-induced changes in amino acids, carbohydrates, and fat. Many types of heat-induced reactions result in the production of meat flavors. Amino acids and reducing sugars react when heated above 110 1C; this thermally induced reaction is called the Maillard reaction and is important in developing meat flavor. The Maillard reaction is influenced by the method of heat transfer. Dry heat methods, especially panfrying, increase the amount of Maillard reaction and moist heat methods prevent the reactions from taking place. A similar effect is achieved using roasting bags when cooking meat in an oven. In addition to the Maillard reaction, lipid degradation products are responsible for developing meat flavor during heating. The lipid degradation reactions take place at a much lower temperature than the Maillard reaction and the flavoring compounds can, therefore, be produced not only on the surface of meat but throughout meat. Lipidderived flavor compounds are very important for the meaty

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flavor and are said to be responsible for the species-specific flavor.

mouth, the structure is intact. During chewing, the meat structure is broken down and soaked in saliva until it is in a state suitable for swallowing. The attributes related to texture can be divided into three groups:

Effect of Cooking on Texture

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The texture of meat determines the feeling in the mouth perceived during chewing. When meat is introduced into the

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In general, these attributes are highly correlated, but they can, to some extent, also vary independently between cuts, depending on the cooking method. Changes in the texture of meat during cooking are due to heat-induced structural changes combined with enzymatic breakdown of proteins. The effect of the time/temperature factor and the core temperature depends on the composition of meat. The M. biceps femoris (BF, outer hind leg muscle) has a high content of connective tissue. It gains more in tenderness when heated slowly than the M. longissimus dorsi (LD, loin), which is low in connective tissue (Figure 4). The effect of core temperature on tenderness depends both on the meat cut (content of connective tissue) and the heating rate. In BF, the tenderness decreases when the core temperature increases from 65 to 75 1C (Figure 5). As meat is slowly heated further up to 80 1C, connective tissue begins to soften and gelatinize and BF becomes more tender. LD, however, becomes less tender when the core temperature increases from 60 to 80 1C, probably owing to the denaturation of actin and myofibrillar toughening. Heating at low temperatures in an oven increases the overall tenderness of the meat compared with the use of medium and high oven temperatures (Figure 6). The effect is largest at 60 1C core temperature and decreases up to 80 1C core temperature. In selecting the optimal core temperature during cooking, attention must be paid to both the muscle and the cooking method. Cooking at temperatures below 100 1C for a long time increases tenderness of meat, but too low temperature does not increase tenderness. Cooking at 58 1C resulted in more tender meat compared with that at 53 1C for

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Figure 4 The effect of cooking method on the tenderness of a pork muscle with a high content of connective tissue compared with one with low content of connective tissue. Different symbols enclosed in the same circle indicate significant differences (po.05). LD, M. longissimus dorsi; BF, M. biceps femoris. Tenderness is expressed in a continuous line scale from 0 to 15 (high intensity). Data plotted from Bejerholm, C., Aaslyng, M.D., 2003. The influence of cooking technique and core temperature on results of sensory analysis of pork – Depending on raw meat quality. Food Quality and Preference 15, 19–30.

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Figure 5 The effect of core temperature on pork tenderness, depending on muscle and cooking procedure. Different letters on the same line indicate significant differences (po.05). LD: M. longissimus dorsi, BF: M. biceps femoris. Tenderness is expressed on a 9-point scale from 0 (extremely tough) to 9 (extremely tender). Modified with permission from Bejerholm, C., Aaslyng, M.D., 2003. The influence of cooking technique and core temperature on results of sensory analysis of pork – Depending on raw meat quality. Food Quality and Preference 15, 19–30.

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See also: Chemical and Physical Characteristics of Meat: Color and Pigment; Palatability. Cooking of Meat: Flavor Development; Maillard Reaction and Browning; Physics and Chemistry; Warmed-Over Flavor. Human Nutrition: Macronutrients in Meat; Micronutrients in Meat. Muscle Fiber Types and Meat Quality. Sensory and Meat Quality, Optimization of. Sensory Assessment of Meat

Further Reading

Core temperature Figure 6 The effect of core temperature on the tenderness of beef M. longissimus dorsi, depending on oven temperature. Tenderness is expressed on a 9-point scale from 0 (extremely tough) to 9 (extremely tender). Data plotted from Cross, H.R., Stansfield, M.S., Koch, E.J., 1976. Beef palatability as affected by cooking rate and final internal temperature. Journal of Animal Science 43 (1), 114–121.

both beef and pork, but meat at both temperatures was very tender for chicken. No difference was seen in tenderness between 58 and 63 1C cooking temperature. The effect of core temperature on juiciness depends more on the cooking method than on the amount of connective tissue in meat. Cooking loss is generally larger when roasting than when panfrying because of the longer cooking time. Increasing the oven temperature results in less juicy meat at the same core temperature. At 65 1C core temperature, there is no difference between roasting and panfrying. With increasing core temperature, the decrease in juiciness is faster when meat is cooked in an oven compared with panfrying, irrespective of the cut.

Effect of Cooking on Weight Loss Cooking loss increases as core temperature increases (see Changes in Meat during Heating; Figure 1). The actual amount of cooking loss depends on the cooking method and the amount of connective tissue in meat. Cooking methods with a very short cooking time, such as panfrying, result in a lower cooking loss than conventional oven cooking methods at the same core temperature. The correlation between cooking time and cooking loss is not linear, as cooking loss is determined by a combination of cooking time and heating rate. Lowtemperature cooking results in lower cooking loss compared with cooking at conventional temperatures. Compared with broiling, roasting results in a lower cooking loss owing to the gentler heating. Cooking loss also differs among cuts. Cuts with a high amount of connective tissue have a higher cooking loss than those with a lower amount of connective tissue. The higher the core temperature, the smaller the difference is between muscle types. Moreover, at 80 1C or more, only minor differences exist among cooking methods and cuts with different amounts of connective tissue.

Anonymous, 1995. Guidelines for Cookery, Sensory Evaluation and Instrumental Tenderness Measurements of Fresh Meat. Centennial, CO: American Meat Science Association and National Live Stock and Meat Board (The National Cattlemen's Beef Association). Bejerholm, C., Aaslyng, M.D., 2003. The influence of cooking technique and core temperature on results of sensory analysis of pork − Depending on raw meat quality. Food Quality and Preference 15, 19–30. Christensen, L., Ertbjerg, P., Aaslyng, M.D., Christensen, M., 2011. Effect of prolonged heat treatment from 48 1C to 63 1C on toughness, cooking loss and color of pork. Meat Science 88, 280–285. Christensen, L., Gunvig, A., Tørngren, M.A., et al., 2011. Sensory characteristics of meat cooked for prolonged times at low temperature. Meat Science 90, 485–489. Cross, H.R., Stansfield, M.S., Koch, E.J., 1976. Beef palatability as affected by cooking rate and final internal temperature. Journal of Animal Science 43 (1), 114–121. Ghazala, S., 1998. Sensory and nutritional aspects of sous vide processed foods. In: Ghazala, S. (Ed.), Sous Vide and Cook-chill Processing for the Food Industry. Gaithersburg: Aspen Publishers, pp. 57–88. Kropf, D., Bowers, J., 1997. Heat-induced changes in meat. In: Bowers, J. (Ed.), Food Theory and Applications, second ed. New York, NY: Macmillan Publishing Co, pp. 615–641. Laakkonen, E., 1973. Factors affecting tenderness during heating of meat. Advances in Food Research 20, 257–314. Lawrence, T.E., King, D.A., Obuz, E., Yancey, E.J., Dikeman, M.E., 2000. Evaluation of electric belt grill, forced-air convection oven and electric broiler cookery methods for beef tenderness research. Meat Science 58, 230–246. Lawrie, R.A., 1998. The eating quality of meat. In: Lawrie, R.A. (Ed.), Lawrie's Meat Science, sixth ed. Cambridge: Woodhead Publishing, pp. 212–257. Martens, H., Stabursvik, E., Martens, M., 1982. Texture and colour changes in meat during cooking related to thermal denaturation of muscle protein. Journal of Texture Studies 13, 291–309. Obuz, E., Dikeman, M.E., Grobbel, J.P., Stephens, J.W., Loughin, T.M., 2003a. Endpoint temperature, cooking method and marbling degree have different effects on Warner−Bratzler shear force of beef longissimus lumborum, biceps femoris, and deep pectoralis muscles. In: Proceedings of the 49th International Congress of Meat Science and Technology, pp. 171−172. Campinas, Brazil: Instituto de Tecnologia de Alime. Obuz, E., Dikeman, M.E., Loughin, T.M., 2003b. Effects of cooking method, reheating, holding time and holding temperature on beef longissimus lumborum and biceps femoris tenderness. Meat Science 65, 841–851. Resurreccion, A.V.A., 1994. Cookery of muscle foods. In: Kinsman, D.M., Kotula, A. W., Breidenstein, B.C. (Eds.), Muscle Foods: Meat, Poultry and Seafood Technology. London: Chapman and Hall, pp. 406–429. Seideman, S.C., Durland, P.R., 1984. The effect of cookery on muscle proteins and meat palatability: A review. Journal of Food Quality 6, 291–314.

Relevant Website www.dmri.dk Danish Technological Institute.

Flavor Development RB Pegg, University of Georgia, Athens, GA, USA F Shahidi, Memorial University of Newfoundland, St. John's, NL, Canada r 2014 Elsevier Ltd. All rights reserved. This article is a revision of the previous edition article by RB Pegg, F Shahidi, volume 2, pp 570–578, © 2004 Elsevier Ltd.

Introduction Flavor is an important sensory characteristic that contributes to the overall palatability of muscle foods. Qualitatively and quantitatively, the flavors associated with cooked meats have proven to be extremely difficult to characterize for both the sensory analyst and the flavor chemist. This is because the sensory impression of meat flavor is influenced not only by compounds contributing to the sensation of taste but more importantly also by those stimulating the olfactory organ. To complicate matters, there is no one single compound or class of compounds that are accountable for meat flavor. Numerous constituents resulting from a myriad of reactions during thermal processing of meat are responsible for the flavor one associates with each animal species. Ultimately, it is the chemical composition of fresh meat that gives the basis for development of a desirable aroma during thermal processing.

The Precursors of Meat Flavor The meat matrix is very complex: its macroconstituents include water, proteins, and lipids, whereas its microconstituents include vitamins (notably B vitamins), peptides, sugars (e.g., ribose), nucleotides, and their metabolites. Raw meat itself does not have much flavor: it has a slight serum-like odor and a blood-like taste. During postmortem aging, hydrolytic activity generates a reservoir of precursor molecules, reactive flavor chemicals, and intermediates, which during thermal processing react/degrade to give the desirable taste tactile properties and aroma characteristics associated with finished meat products. For the generation of meat flavor to occur, meat and meat products must be heated/cooked/thermally processed. Thermal processing induces a complex network of chemical reactions among the nonvolatile components of lean and fatty tissues present in meat and yields a heterogeneous system containing many volatile compounds with odoriferous properties, smaller nonvolatile compounds with taste properties, as well as flavor potentiators and synergists. The type of thermal processing employed, such as grilling, roasting, broiling, stewing, boiling, or smoking, and the final internal temperature of the product contribute significantly to the formation and stability of both volatile and nonvolatile compounds and are, therefore, related, at least to some extent, to the differences in the overall meat flavor sensation. The present working theory is that aroma volatiles are derived from nonvolatile precursors in the lean and fatty tissues of meat during cooking. These precursors can be further subdivided into water- and lipid-soluble components. Basically, meat aroma is the composite sensation of low molecular

Encyclopedia of Meat Sciences, Volume 1

weight products of the Maillard reaction (i.e., a nonenzymatic browning reaction between amino groups, such as those associated with amino acids, and with a carbonyl group of a reducing sugar) as well as the thermal melting and oxidative degradation of lipids. Lipids would also more likely participate in the Maillard reaction, as the carbonyls produced from lipid oxidation can replace the carbonyls on reducing sugars. These oxidation products can produce desirable flavors such as those in fried foods, but some lipid oxidation reactions often result in negative flavors. A detailed discussion on the role of the Maillard reaction, as it relates to meat flavor development, is discussed in another article. A delicate balance exists between the aroma volatiles generated from Maillard and lipid reactions as well as their interaction with one another and molecular oxygen. It is this balance that dictates whether the desirable meaty/savory, fatty flavor or warmed-over or off-flavors will result. Although the odor threshold values (OTVs) of sulfur- and nitrogencontaining heterocyclic compounds, which contribute to meaty/savory notes, are lower than those of lipid-derived volatiles, changes in meat flavor are the result of a dynamic process. With time, the levels of lipid-derived compounds increase and eventually overwhelm the desirable meaty notes of products, even though many of these compounds' OTVs are several degrees of magnitude greater than those of the heterocyclic compounds. Such changes to the perception of meat flavor make its characterization difficult.

Makeup of Meat Flavor: Taste and Odor Flavor is a wide sweeping term that encompasses not only the taste and aroma associated with cooked meat but also the intangibles like texture, mouthfeel, and temperature sensation. The human tongue has millions of gustatory receptors in which one uses to identify taste. There are only five recognized classes of taste: sweet, sour, salty, bitter, and umami (i.e., a Japanese term for a fifth basic taste that is triggered by some amino acids, peptides, and their salts, notably monosodium glutamate). Umami is difficult to translate, but some equivalent English terms are savory, essence, pungent, deliciousness, and meaty. However, it is the volatile constituents of meat that account for the dominant sensory phenomenon that one refers to as flavor. To date, more than 1000 compounds have been identified in the aroma profiles of cooked meat products. The volatiles are a combination of low molecular weight products from the degradation of amino acids and lipids via oxidation as well as further reaction products from these aforementioned degradation compounds. The resulting products include a broad array of compounds from varying classes of chemicals: these

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Cooking of Meat | Flavor Development happens in terms of meat flavor generation; nevertheless, it provides a good basis for discussion.

include hydrocarbons, aldehydes, alcohols, ketones, carboxylic acids, ethers, esters, lactones, and S-, N-, and O-containing heterocyclic compounds. Some examples are provided in Figure 1. There is a simplified theory: it states that the basic flavor of cooked meat is similar to all species, that is, flavors derived from protein breakdown (e.g., Maillard reaction) and from the formation of heterocyclic compounds such as pyrazines, pyrroles, thiazoles, oxazolines, thiolanes, thiophenes, and furans are similar. The species-specific flavors come from the lipid constituents of meat. It is the melting and/or oxidation of lipid constituents that contributes toward the species-specific flavors identified in meat products. It is now known that lipid oxidation products interact with Maillard reaction products to generate new flavors associated with cooked meat. So, the foregoing theory is an oversimplification of what actually

Sources of Heat-Induced Meat Flavor The Decomposition of Individual Substances The degradation of mono- and oligosaccharides to yield volatile compounds involves temperatures greater than those generally associated with the cooking of meat. Nevertheless, some decomposition of simple sugars to furanones and furfurals can occur during cooking/heating/thermal processing of meat. Amino acids tend to be more stable and unlikely to undergo pyrolysis. Only along the surface of grilled or roasted meat, where localized dehydration allows the temperature to

Compounds derived from lipid precursors

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Figure 1 Some classes of volatile compounds generated during the cooking of meat. Reprinted from Mottram, D.S., 1998. Flavor formation in meat and meat products: A review. Food Chemistry 62, 415–424.

Cooking of Meat | Flavor Development rise significantly above the boiling point of water, does pyrolysis of amino acids take place, and this results in decarboxylation and deamination reactions. Breakdown of protein into oligopeptides, peptides, and free amino acids is also important because these protein subunits, monomers, or their salts are taste active but contribute very little to the aroma of cooked meat. During heat processing, free amino acids in meat, like cysteine, react with reducing sugars (products of glycolysis) via the Maillard reaction to generate aroma volatiles. Products of one reaction often become precursors for another. One can begin to appreciate why the chemistry underlying meat flavor is a complex topic. Thiamine (i.e., vitamin B1) is an important microconstituent in the meat matrix that significantly impacts meat flavor development. It is a sulfur-containing compound with a thiazole and pyrimidine ring system. When meat is thermally processed, the vitamin degrades and potent aromas are generated, of which some have been described as meaty. Thiamine's breakdown products include thiophenes, thiazoles, furans, furanthiols, hydrogen sulfide, and bicyclic heterocyclic compounds. An important degradation product from thiamine is 5-hydroxy-3-mercapto-2-pentanone: this very reactive compound is the intermediate for a number of thiols, including 2-methyl-4,5-dihydro-3-furanthiol and 2-methyl-3furanthiol as well as the mercaptoketones. The breakdown of lipid constituents and their subsequent oxidation, as it relates to cooked meat flavor, is described in a separate section below.

Maillard Reaction/Advanced Glycation Endproducts Although a description of the Maillard reaction, as it relates to meat and meat products, is presented in detail in another article, a brief overview of the reaction is provided for the sake of completeness. Free amino groups of amino acids or peptides in meat can react with reducing sugars in the presence of heat. They undergo a series of complex nonenzymatic browning reactions known simply as the Maillard reaction. Maillard reaction products are sometimes intermediates for further reactions and in other cases, end products. There is confusion at times in the terminology with advanced glycation endproducts (AGE), which are the result of a chain of reactions after an initial glycation reaction. The Maillard reaction, which does not require the very high temperatures associated with sugar caramelization and protein pyrolysis, is one of the most important routes for the generation of flavors in cooked foods. Its products include high molecular weight brown-colored compounds, known as melanoidins, and volatile aroma compounds. The first step of the Maillard reaction in a complex series of interactions involves the formation of an N-substituted glycosylamine via the addition of the carbonyl group of the open-chain form of a reducing sugar with a primary amino group of an amino acid, peptide, or protein. The N-glycosylamine rearranges itself, forming an Amadori compound, which can degrade further, thus generating compounds such as furfurals, furanones, and dicarbonyls. These compounds may themselves make some contribution to meat flavor but are more important as substrates in the generation of other aroma volatiles. For example, they can interact with

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reactive compounds such as amines, amino acids, hydrogen sulfide, thiols, ammonia, acetaldehyde, and other aldehydes. These further reactions lead to many important classes of meat flavor compounds such as pyrazines, oxazoles, thiophenes, thiazoles, and other heterocyclic compounds. As will be outlined below, sulfur compounds derived from the interaction of cysteine and ribose seem to be particularly important for the characteristic aroma of meat. Although the Maillard reaction can take place in aqueous solution, it occurs much more readily at low moisture levels; hence, in meat, flavor compounds produced by the Maillard reaction tend to form on the surface of the product where some dehydration has occurred.

Lipid Oxidation In the early 1960s, two researchers suggested that meat aroma, derived from water-soluble precursors of lean tissue, was similar in all cooked meat and that the characteristic species differences were due to the contribution of volatiles derived from the lipid fraction. It was postulated that lipids provide volatile compounds that give the characteristic flavors of different species and that elimination of the lipid-derived flavors should reveal the true-to-nature flavor of meat itself. Fat influences flavor by producing organoleptically significant quantities of carbonyl compounds (i.e., aldehydes and ketones) as a result of oxidation from unsaturated fatty acids and by acting as a depot of fat-soluble compounds that volatilize on thermal processing. The spectrum of secondary products of lipid oxidation will depend, of course, on the fatty acid composition of adipose and intramuscular tissues, which vary from one species to another and may be influenced by diet. For example, the deposited lipids of monogastric animals, essentially pigs and poultry, can be influenced by the fatty acid patterns in the animals' diet. With the meat industry edging further into the functional foods sector, researchers have been attempting to increase omega-3 fatty acid levels in the meat from monogastrics. However, quality challenges of these functional meats in the form of oxidation/off-flavors exist in the cooked products, even with the supplementation of vitamin E to the diet. One of the main functions of thermal processing is to generate aroma and flavor precursors from lipids, many of which possess intense odors, as well as to allow intimate mixing of fat- and water-soluble compounds. Yet, lipids alone are not responsible for the species-characteristic aromas. A study reported that the addition of pork backfat to either beef or pork lean meat resulted in a substantial increase in hexanal levels after thermal processing of the preparations but only small changes in most other volatiles. The lack of a relationship between aroma constituents and subcutaneous fat levels suggested that the triacylglycerols of adipose tissue may not be the main precursors for volatiles; instead, intramuscular triacylglycerols and structural phospholipids were deemed to be important.

Interaction between Lipid Oxidation and Maillard Reaction Products Sensory panels and consumer studies have also failed to find a direct relationship between the flavor of lean meat and the

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quantity of fat on the carcass; thus, giving credence to early meat flavor research that meatiness was associated with the water-soluble flavor precursors, whereas species characteristics were derived from the lipids. The aroma of cooked meat is dominated by lipid-derived volatiles and such volatiles are expected to have some effect on meaty flavor. Triacylglycerols and structural phospholipids have been carefully studied in relation to meat flavor development. In a nutshell, phospholipids play a key role during the thermal generation of meat aroma. In a study where inter- and intramuscular triacylglycerols were extracted from lean meat samples before cooking, the aroma of the thermally processed products indicated that removal of these fats had little effect on the meaty aroma and the volatile compounds were formed on heating of the samples; in fact, one could not differentiate the aroma profile from that of untreated material. This was not the case, however, when phospholipids were also extracted from the muscle tissue. Elimination of phospholipids along with the triacylglycerols resulted in a marked loss in the perceived meatiness of the overall aroma, and the odor descriptor changed from that of meaty to roast or biscuit like. Another significant observation was that removal of phospholipids from the meat before thermal processing brought about a significant increase in certain volatile heterocyclic compounds, notably alkyl pyrazines. As the primary source of these compounds in cooked meat comes via the Maillard reaction, it appeared that interaction of phospholipids or their degradation products in the Maillard reaction is important for the characteristic aroma of cooked meat. In a model system study containing cysteine and ribose, the interaction of phospholipids in the Maillard reaction of these two substrates not only increased the meaty aroma of the reaction mixture but also increased the number of compounds possessing meaty notes. In other words, research has suggested that the interaction between phospholipids and the Maillard reaction can affect meat flavor in three ways: (1) lipid–Maillard reaction products can have their own aroma characteristics; (2) compounds with low OTVs derived from lipid oxidation, such as unsaturated aldehydes, can react with Maillard intermediates and thereby reduce their contribution to rancid and other odors (e.g., green note); and (3) important Maillard intermediates, such as ammonia and hydrogen sulfide, can react with lipid-derived volatiles, thereby reducing their availability for the formation of cooked flavors.

Species Effect The chemistry of compounds bringing about distinctive species-related flavors of ruminant meats remains obscure. The characteristic flavor of different meat species is generally believed to be derived from their respective lipid profiles. The interaction of lipid constituents with other meat components (e.g., Maillard reaction products, as outlined above) is most likely involved. Numerous reports have shown that the chemical nature of many flavor volatiles of meat from different species is similar qualitatively but different quantitatively. Lamb, mutton, and goat meat are, however, exceptions. A number of volatile, medium-chain fatty acids (C5–C12), including some methyl-branched chain homologs, have been

identified in cooked sheep and goat meats. These saturated fatty acids have not been reported in other meats and were associated with the characteristic ‘sweaty’ flavor of cooked sheep meat that results in its low consumer acceptance in many countries. In particular, 4-methyloctanoic, 4-ethyloctanoic, and 4-methylnonanoic acids are considered to be primarily responsible for this off-flavor. It has also been reported that mutton aromas contain a higher concentration of 3,5dimethyl-1,2,4-trithiolane and 2,4,6-trimethylperhydro-1,3,5dithiazine (thialdine) as compared with those of other species. Additional sulfur-containing compounds were present at notable concentrations and this was attributed to the high content of sulfurous amino acids in mutton as compared with those of beef and pork. Similarly, a marked concentration of alkyl-substituted heterocycles and alkylphenols was noted in mutton volatiles.

Other Effects Antemortem factors such as the breed, sex, nutritional status, and age of the animal; preharvest stress/handling conditions; and postmortem factors like muscle type, myoglobin content, pH, and thermal processing conditions (i.e., moist heat, dry heat, microwave, convection oven, and final endpoint cook temperature) of the meat products, including the type and duration of storage, all contribute to and affect the flavor of meat. Another important parameter in relation to meat flavor is the diet that animals are fed. For instance, ruminants either graze on grass or are fed hay and silage diets. For those animals feeding on pastoral lands with its great biodiversity, the diets are often switched over to cereal or grain-based ones a number of weeks before harvest, as a means to improve the flavor characteristics of the resultant meat. Skatole (i.e., 3methylindole) is a natural product that animals ingest from pastoral lands. In sheep meat, skatole in combination with the branched-chain fatty acids discussed above can impart objectionable flavors to the meat products derived from these animals. The effect of skatole is less noticeable in cattle, but the consumption of grass also causes animals to accumulate larger concentrations of linoleic and α-linolenic acids and their derivates (e.g., conjugated linoleic acid). Consequently, any detectable pastoral flavor in meat products tends to result from oxidation products of α-linolenic acid. As described in the warmed-over flavor (WOF) article, researchers are supplementing the feed of domesticated species with dietary antioxidants like vitamin E. Supplementation in the form of α-tocopheryl acetate to the diet of monogastric animals before harvest can, in some cases, improve the flavor of finished products by minimizing the potential for WOF development. This effect has been seen in a number of studies where the basal diets of hogs have been supplemented with increasing levels of α-tocopheryl acetate. A progressive increase in the concentration of α-tocopherol has been found in the muscle tissue, mitochondria, and microsomes of hogs. α-Tocopherol migrates into muscle cell membranes, where it lies adjacent to highly oxidizable phospholipids; this localization makes it a particularly effective antioxidant. Sensory studies of meat products have confirmed that vitamin E supplementation can prolong flavor freshness of cooked products

Cooking of Meat | Flavor Development and retard WOF development. As aforementioned, the addition of α-tocopheryl acetate to omega-3 fortified diets (e.g., in the form of flaxseed) of monogastrics does not always sufficiently curb oxidation of polyunsaturated fatty acids.

Desirable Meaty Aromas of Cooked Meat In studying meat aroma, two realities exist: first, a means in which to ‘trap’ meat flavor volatiles and second, a way to separate and identify the odor impact compounds. Analyzing the volatile organic compounds that impact meat flavor is not an easy task. As noted above, more than 1000 compounds have been identified in the volatile constituents of cooked red meats and poultry by gas chromatographic–mass spectrometric techniques. Obtaining useful information from the analysis of meat volatiles, however, can be even more challenging than the isolation/identification steps themselves. The critical question becomes, “What is the relative sensory significance of these thermally derived volatiles?” The answer is not totally clear, but many volatiles are relatively unimportant. For example, aliphatic and aromatic hydrocarbons, saturated alcohols, carboxylic acids, esters, ethers, and carbonyl compounds (i.e., aldehydes and ketones) are probably not the main contributors to desirable meaty flavor. Rather, lactones; acyclic sulfur-containing compounds (i.e., mercaptans and sulfides); nonaromatic heterocyclic compounds containing sulfur, nitrogen, or oxygen (e.g., hydrofuranoids); and aromatic heterocyclic compounds containing sulfur, nitrogen, or oxygen (e.g., pyrazines and thiophenes) possessed characteristic meaty flavor notes. Whether a compound is a key aroma impact substance depends on both its concentration and OTV. Gas chromatography–olfactometry (GC–O) coupled with aroma extraction dilution analysis has assisted with identifying key aroma impact compounds in cooked meat. The importance of sulfur-containing heterocyclic compounds in the volatiles of cooked meats should not be underestimated. Although these compounds are present in very low concentrations, their parts-per-billion OTVs make them potent aroma compounds. As an example, 2-methyl-3(methylthio) furan was identified in cooked beef and found to have an OTV of 0.05 mg kg−1 and a meaty aroma at levels below 1 mg kg−1. The interest in such compounds stems partly from research into developing simulated meat flavorings with desirable meaty aroma characteristics for use in processed food products. Dr. Donald Mottram and his research group in the United Kingdom have carried out extensive work on characterizing the importance of heterocycles in desirable meaty aromas. The breakdown of cysteine (e.g., via hydrolysis or Strecker degradation) and thiamine in meat gives hydrogen sulfide, which is critical in the formation of S-containing heterocycles. Hydrogen sulfide can react with dicarbonyls, furanones, and furfurals – most likely generated from inosine 5′-monophosphate, ribose 5-phosphate, and ribose via the Maillard reaction – to yield thiol and mercaptoketone derivatives. These derivatives can undergo oxidation and result in quite a number of symmetrical and unsymmetrical disulfides; some of these are depicted in Figure 2. Various odor descriptors from GC–O studies have been employed to characterize some of

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these compounds and include the following: cooked meat, meaty, brothy, pungent, fried onion, sulfury, fatty, nutty, and roasted. Heterocyclic compounds with one, two, or three sulfur atoms in five and six-membered rings are much more prevalent in boiled than in roasted meats. The meaty character of some sulfur-containing compounds depends on the position of the thiol group and the degree of unsaturation. For instance, furans and thiophenes with a thiol group in the 3-position and their related disulfides have been reported to possess strong meat-like aromas with very low OTVs, whereas those with the thiol in the 2-position were characterized as being burnt and sulfurous. One researcher noted that the best meat-like aroma is produced when there is a methyl group adjacent to the thiol moiety and the ring contains at least one double bond. A complication in the analysis of such compounds arises from the fact that the aroma of these sulfur volatiles, which is pleasant at the levels found in meat, becomes objectionable at higher concentrations. Therefore, when assessing the flavor quality of muscle foods, both qualitative and quantitative aspects of volatiles must be considered.

Flavor of Nitrite-Cured Meat Nitrites and nitrates are unique ingredients found in processed cured meat products. Nitrite plays a multifunctional role in the meat matrix: it is responsible for the development of the characteristic color associated with cured meat; a distinct flavor that distinguishes the flavor of cured ham from cooked, uncured pork, and this may be related to the antioxidative capacity it imparts; and in combination with sodium chloride, it suppresses the outgrowth and production of toxin from the anaerobic bacterium, Clostridium botulinum. The mechanism by which nitrite imparts a characteristic cured flavor to thermally processed meat and meat products (i.e., a flavor that distinguishes cooked ham from pork) is unclear. Nevertheless, cured meat flavor is probably a composite sensation derived from contributions of many odoriferous compounds. Research into cured meat flavor has been divided into two main areas, namely, the sensory evaluation of flavor imparted to meat by nitrite and the qualitative and quantitative identification of volatile and nonvolatile components responsible for it, but caution must be exercised. A compound-by-compound search of meat flavor volatiles might misidentify the true nature of cured meat flavor, because a mixture of two or more odors can produce an aroma that is perceived as qualitatively distinct from the odors of their components. Nitrite's role in the development of thermally derived cured meat flavor involves its antioxidative activity, which retards the breakdown of unsaturated fatty acids and the formation of secondary oxidation products. Numerous researchers have attempted to identify the volatile compounds generated during the thermal processing of cured meat. The results indicate that all compounds identified were also contributors to the aroma of uncured cooked meat. Some important research in the 1960s involved the examination of the volatile constituents isolated from uncured and cured hams by gas chromatography. Qualitatively, the volatile compounds of cured ham were similar to uncured hams but were quantitatively

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O

SH

O

SH SH

O

SH

3-mercapto2-butanone

2-mercapto3-pentanone

Sn

O

2-methyl-3-furanthiol

2-furanmethanethiol

CH3

where, n = 1, 2 or 3

Sn

CH3

O

CH3

where, n = 2 or 3

O

2-methyl-3-(methylthio)furan

2-[(methyldithio)methyl]furan and trithio homologue

and dithio and trithio homologues

O S

S

S

S

S

S

O O

CH3 H3C

O

CH3

O

bis(2-methyl-3-furanyl) disulphide

CH3

O

2-methyl-3-[2-(furanylmethyl) dithio]furan

CH3

2-[(2-methyl-3-furanyl) dithio]-3-pentanone

O

O CH3

S

S

S R

O

S R

O

where, R = CH3 and C2H5

where, R = CH3 and C2H5

1-[(2-furanylmethyl)dithio]2-propanone and -2-butanone

2-[(2-furanylmethyl)dithio]3-butanone and -3-pentanone

O S Sn

O

O where, n = 2 or 3

bis(2-furanylmethyl) disulphide and trisulphide homologue

O

S

CH3 1-[(2-methyl-3-furanyl) dithio]-2-propanone

Figure 2 Some thiols and sulfides detected in the headspace volatiles of heated meat systems. Adapted from Mottram, D.S., Madruga, M.S., 1994. Important sulfur-containing aroma volatiles in meat. In: Mussinan, C.J., Keelan, M.E. (Eds.), Sulfur Compounds in Foods. ACS Symposium Series, vol. 564. Washington, DC: American Chemical Society, pp. 180–187. Copyright (1994) American Chemical Society.

different. Hexanal and pentanal were present in appreciable amounts in the volatiles of uncured but were barely detectable in the volatiles of cured ham. It was suggested that the absence of these aldehydes and those of higher molecular weight aldehydes was responsible for the flavor differences between cured and uncured hams. It was also noted that

the volatiles, after passage through a solution of 2,4-dinitrophenylhydrazine (2,4-DNPH), had the characteristic curedham aroma, regardless of whether cured or uncured hams were used. Cured and uncured chicken and beef volatiles, after stripping their carbonyl compounds by passage through 2,4DNPH solutions, also possessed an aroma similar to that of

Cooking of Meat | Flavor Development

383

Fresh meat

Curing (addition of NaCl and NaNO2)

Analysis of volatiles (by GC, GC−MS, GC−O, AEDA or sensory)

Species differentiation (complex spectrum; lipid oxidation volatiles)

Thermal processing (generation of meaty flavors; products of Maillard reaction, some lipid oxidation and Maillardlipid oxidation interactions)

Thermal processing (generation of cured meat flavor; Maillard reaction products, little or no oxidation)

Storage (cured meat flavor persists; little oxidation and no WOF development)

Storage (progressive oxidation with a noticeable loss or masking of desirable meaty notes)

Analysis of volatiles

Analysis of volatiles (by GC, GC−MS, GC−O, AEDA or sensory)

Solution of 2,4-DNPH

Analysis of volatiles

Basic meat flavor (simplified spectrum of volatiles with reduced levels of carbonyls)

Deterioration in meat flavor (complex spectrum; richer in carbonyls from lipid oxidation; reheated products exhibiting WOF)

Figure 3 Consequence of thermal processing, nitrite curing, and storage on meat flavor. AEDA, aroma extraction dilution analysis; GC, gas chromatography; GC–MS, gas chromatography–mass spectrometry; GC–O, gas chromatography–olfactometry; WOF, warmed-over flavor; 2,4-DNPH, 2,4-dinitrophenylhydrazine. Adapted from Shahidi, F., 1992. Prevention of lipid oxidation in muscle foods by nitrite and nitrite-free compositions. In: St. Angelo, A.J. (Ed.), Lipid Oxidation in Food. ACS Symposium Series, vol. 500. Washington, DC: American Chemical Society, pp. 161–182. Copyright (1992) American Chemical Society.

cured ham. A conclusion reached was that treating meat with nitrite does not seem to contribute any new volatile compounds to the flavor of cooked meats, with the exception of nitrogen oxides that are not present in cooked uncured meat. Therefore, it was postulated that cured-ham aroma represents the basic flavor of meat derived from precursors other than triacylglycerols and that the aromas of various types of cooked meat depend on the spectrum of carbonyl compounds derived by lipid oxidation. An oversimplistic view attempting to provide a unifying theory on the origin of the thermally generated flavor of meat, species differentiation, and off-flavor development is provided in Figure 3. It postulates that meat acquires its characteristic species-specific flavor on cooking from volatile carbonyl compounds formed by oxidation of its lipid components (i.e., primarily phospholipids) and their reaction products after interaction with Maillard reaction products. Further oxidation during storage of cooked meat results in the deterioration of desirable meaty notes. Curing with nitrite suppresses the formation of oxidation products. Hence, it may be assumed that the flavor of nitrite-cured meats is actually the true-to-nature flavor of meat from different species without being influenced by overtone carbonyls derived from oxidation of their lipid components. The postulate, however, does not easily explain the fact that the intensity of cured

meat flavor in bacon has been reported to be proportional to the level of ingoing nitrite levels, whereas the characteristic ‘mutton’ flavor is persistent regardless of the level of nitrite used in curing of sheepmeat.

See also: Cooking of Meat: Maillard Reaction and Browning; Physics and Chemistry; Warmed-Over Flavor

Further Reading Brewer, M.S., 2009. Irradiation effects on meat flavor: A review. Meat Science 81, 1–14. Calkins, C.R., Hodgen, J.M., 2007. A fresh look at meat flavor. Meat Science 77, 63–80. Martins, S.I.F.S., Leussink, A., Rosing, E.A.E., Desciaux, G.A., Boucon, C., 2011. Meat flavor generation in complex Maillard model systems. In: Mottram, D.S., Taylor, A.J. (Eds.), Controlling Maillard Pathways to Generate Flavors. ACS Symposium Series, vol. 1042. Washington, DC: American Chemical Society, pp. 71−84. Melton, S.L., 1999. Current status of meat flavor. In: Xiong, Y.L., Ho, C.-T., Shahidi, F. (Eds.), Quality Attributes of Muscle Foods. New York: Kluwer Academic/Plenum Publishers, pp. 115–133. Mottram, D.S., 1998. Flavour formation in meat and meat products: A review. Food Chemistry 62, 415–424.

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Mottram, D.S., Elmore, J.S., 2002. Novel sulfur compounds from lipid-Maillard interactions in cooked meat. In: Reineccius, G.A., Reineccius, T.A. (Eds.), Heteroatomic Aroma Compounds. ACS Symposium Series, vol. 826. Washington, DC: American Chemical Society, pp. 101−109. Mottram, D.S., Madruga, M.S., 1994. Important sulfur-containing aroma volatiles in meat. In: Mussinan, C.J., Keelan, M.E. (Eds.), Sulfur Compounds in Foods. ACS Symposium Series, vol. 564. Washington, DC: American Chemical Society, pp. 180−187. Pegg, R.B., Shahidi, F., 2000. Nitrite curing of meat. The N-nitrosamine Problem and Nitrite Alternatives. Trumbull, CT: Food & Nutrition Press, Inc. Shahidi, F., 1992. Prevention of lipid oxidation in muscle foods by nitrite and nitrite-free compositions. In: St. Angelo, A.J. (Ed.), Lipid Oxidation in Food. ACS Symposium Series, vol. 500. Washington, DC: American Chemical Society, pp. 161−182. Shahidi, F. (Ed.), 1998. Flavor of Meat, Meat Products and Seafoods, second ed. London, UK: Blackie Academic & Professional.

Shahidi, F., Rubin, L.J., D'Souza, L.A., 1986. Meat flavor volatiles: A review of the composition, techniques of analysis, and sensory evaluation. CRC Critical Reviews in Food Science and Nutrition 24, 141–243. Spanier, A.M., Flores, M., Toldrá, F., et al., 2004. Meat flavor: Contribution of proteins and peptides to the flavor of beef. In: Shahidi, F., Spanier, A.M., Ho, C.-T., Braggins, T. (Eds.), Quality of Fresh and Processed Foods. Advances in Experimental Medicine and Biology, vol. 542. New York: Kluwer Academic/ Plenum Publishers, pp. 33–49. Vasta, V., Priolo, A., 2006. Ruminant fat volatiles as affected by diet. A review. Meat Science 73, 218–228. Wang, R., Yang, C., Song, H., 2012. Key meat flavour compounds formation mechanism in a glutathione−xylose Maillard reaction. Food Chemistry 131, 280–285.

Heat Processing Methods SJ James and C James, The Grimsby Institute of Further & Higher Education (GIFHE), North East Lincolnshire, UK r 2014 Elsevier Ltd. All rights reserved. This article is a revision of the previous edition article by SJ James, C James, volume 2, pp 599–606, © 2004 Elsevier Ltd.

Glossary Convection, thermal Mechanism for heat transfer. The process of heat transfer through a liquid or gas by means of circulating currents caused by changes in density. Heat transfer coefficient Coefficient used in thermodynamics to calculate heat transfer, typically by convection or phase change, between a fluid and a solid. Pasteurization A form of heat treatment that kills certain vegetative bacteria and spoilage organisms in milk and other foods. Temperatures below 100 °C are used.

Introduction Cooking is the most common heat treatment applied to meat; its primary aim is to cause structural and chemical changes that will make the meat more palatable. Industrially, the aim is more often to pasteurize the meat, for example, kill vegetative pathogens and spoilage organisms and to extend the safe shelf life of the product, with the consumer completing the cooking process at home. Sterilization extends the shelf life even further by killing all of the microorganisms present, including the spores. The organoleptic changes that are caused by heat treatment (doneness, flavor, firmness, consistency, and cured-meat color development) are time−temperature-dependent processes. The basic effect of the heat treatment is the coagulation of meat proteins. Between 70 and 80 °C, the majority of meat proteins are completely coagulated; these structural changes of proteins are responsible for the characteristic firmness of heat-treated meat products. Products containing connective tissue become tenderer owing to solubilization of the collagen (gelling), such as cuts of meat. Frankfurters have an elastic firmness, and on reheating before consumption become even firmer. Products such as meat paste that are in a liquid state before heating change, becoming more viscous and attain a ‘spreadable’ consistency. There are also a number of other heat treatments used during slaughtering operations for both red and poultry meat production. Poultry and pork carcasses are scalded, and pork carcasses singed. Surface heat decontamination processes have also been developed for meat.

Sterilization Commercial sterilization is intended to produce an ambient stable product with a long shelf life by destroying both microbial and enzyme activity. The severity of the heat treatment produces substantial changes in the nutritional and sensory qualities of the meat. ‘Commercial’ sterilization implies that there is a very low probability of the survival of microorganisms

Encyclopedia of Meat Sciences, Volume 1

Radiation, thermal It is a mechanism for heat transfer. Electromagnetic radiation generated by the thermal motion of charged particles in matter. All matter with a temperature greater than absolute zero emits thermal radiation. Refrigeration It is defined as the process of removing heat from any substance to (1) render the substance colder, for example, reduce temperature, (2) change its state, for example, water to ice, (3) maintain its state, for example, preserving foods, storing ice.

that are injurious to human health. It does not, however, mean that there are no microorganisms left in the food. Although the pH of meat is generally slightly acidic, it is considered a low acid food (pH higher than 4.5) in danger of supporting Clostridium botulinum and so must be given a severe enough treatment to inactivate spores of this organism. Although these spores are not as resistant as the spores of some other Clostridium and Bacillus types, C. botulinum is capable of producing lethal toxins, sometimes without swelling the container or obvious alteration of the appearance of the product. Because this organism presents a public health risk, recommended heat treatments must have a large safety margin. The severity of heat processes for canned meat products is measured in terms of F0 values, which means that the product received a heat treatment with the same inactivating effect as exposure for one minute at 121 °C. For example, one minute at 121 °C gives the same amount of inactivation of spores as 4 min at 115 °C or 13 min at 110 °C, for example, all those processes have the same F0 value. The F0 value for the majority of canned meat products ranges between 1 and 10. Meat processed in large cans requires longer processing times to allow for heat penetration; consequently, closer to the surface F0 values can be between 20 and 25. Traditional canning is a nonsteady state heat transfer process in which a container is heated, held at a given temperature for a given time, and then cooled. The whole heating/holding/ cooling cycle contributes to the sterilization. The vessels used for sterilization are commonly called retorts and the process retorting. Heat can be provided by three methods, each being more suitable for different containers. Traditionally canned meats, such as corned beef, are processed by steam inside a pressure vessel. Latent heat is transferred to the food when the saturated steam condenses on the outside of the container. Air must be removed from the retort to prevent it forming a noncondensable area around the can and preventing the steam condensing on the surface. After sterilization the cans are usually cooled with water. An overpressure is used to prevent strain on the can seams (pressure

doi:10.1016/B978-0-12-384731-7.00132-X

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cooling). When the food has cooled to below 100 °C, the overpressure of air is removed and cooling continues to approximately 40 °C. At this temperature, moisture on the can dries to prevent surface corrosion, and allow label adhesives set more rapidly. Meats and meat products in glass containers or flexible pouches are processed under hot water with an overpressure of air. Processing meat products in glass containers is slower than in cans or pouches because the glass has a lower thermal conductivity and has to be thicker to provide adequate strength. There is also a higher risk of thermal shock during processing glass containers. Although the plastics used for pouches have a low thermal conductivity, the thinness of the plastic and the smaller cross-section of the container means that processing is often faster than for cans. The flexible nature of the pouches and their use for liquid or semiliquid meat products, such as sauces and chili con carne, can cause a problem. Vertical packs promote better circulation of hot water in the retort, but frames are needed to prevent the pouches from bulging at the bottom, which would increase the thickness of the pouch and hence decrease the rate of heat penetration and increase the process time. Processing the pouches horizontally ensures that the thickness is constant across the pouch. Alternatively, the packs can be circulated through an agitated system where the motion of the water stirs the packs, ensuring mixing of the contents and good heat transfer, provided the system has been properly designed. An alternative to steam or hot water is direct flame heating. Flame sterilization involves heating cans by passing them over a gas flame. This method is extremely fast because the flame is at temperatures in excess of 1500 °C and internal temperatures can reach 116 °C in a few minutes. The cans are closed under a very high vacuum then pass through a four-stage process: the cans are first preheated in steam; the cans then pass over a gas flame while agitated to stir the contents; the cans are held for the required holding time; then the cans are cooled. The entire operation of preheat, process to 130 °C, hold and cool can take only 12 min. However, the process is limited to low viscosity liquids or solids, such as cubed beef or ham. The internal pressure in the can during processing is very high (275 kPa at 130 °C), and this may strain the can seams and limits the process to small cans. These processes can be batch or continuous. Continuous retorts permit close control over the processing conditions; gradual changes in the pressure inside the food container can be made and therefore less stress is placed on the container than

Table 1

with batch equipment. However, they are less flexible than batch systems, and in practice, are used for the production of high-volume products where there is no requirement to regularly change the container size or processing conditions.

Cooking (Pasteurization) Many commercial pasteurization processes differ little from those used in the catering and domestic environments. Often, with the exception of meat products that are to be eaten cold (i.e., ready-to-eat products), the heat treatment is carried out to pasteurize (kill the vegetative pathogenic and spoilage microorganisms) and not necessarily cook them, because they will often be heated by the consumer before ingestion. Pasteurized products require chilled or frozen storage to prevent proliferation of any microorganisms not killed in the pasteurization process. The time to chill the product from cook temperatures is often as important as the internal cooked temperature attained. The microbiological criteria for pasteurized meats is often based on Listeria monocytogenes (considered the most dangerous heat-tolerant pathogen in many chilled products), with a recommendation to cook to 70 °C for 2 min, or equivalent. C. botulinum is viewed as a potential hazard in vacuum-packed products and requires a much more severe treatment, 10 min at 90 °C, or equivalent. Textbooks on cooking use a wide variety of terms to describe cooking (Table 1). Conventional commercial cooking systems for meat joints and products are based on roasting/ baking, boiling, or frying methods. Microwaves are commonly used in reheating, and some cooking processes and ohmic heating has been advocated for some products. Surface heat transfer coefficients with foodstuffs in boiling and frying operations are much higher than in hot air ovens (Figure 1). However, in unpressurised systems water temperatures are below 100 °C and the temperature difference between the food and cooking environment can be much less than in a hot air oven operating at 200–360 °C. Condensing steam results in high surface heat transfer coefficients but is only suitable for a small range of products.

Hot Air The majority of cooked meat and many individual meat products are roasted or baked in hot air ovens. These ovens

Common cooking methods/terms

Boiling Steaming Stewing Roasting Braising Baking Grilling/broiling Shallow frying Deep frying Microwaving

Cooking of foods in a liquid, usually stock or water Cooking in moist heat where the water exists as a vapor, generally above 100 °C Slow cooking in a small quantity of water, stock, or sauce in which the food is always cut up and the food and cooking liquid are served together The subjection of food to the action of heat in an oven, or while it is roastingon a spit; in both cases, fat is used as a basting agent A combination of roasting and stewing in a pan with a tight-fitting lid Same as roasting, except no fat is used Cooking with radiated heat Cooking the food in hot shallow fat in a pan Cooking the food by completely submerging it in hot fat A colloquial term for microwave cooking

Cooking of Meat | Heat Processing Methods commonly consist of either a compartment with shelves for the product or a long tunnel through which the product is transported on a conveyor belt. The heat transfer medium is air, which is sometimes mixed with steam. The heat transfer mechanism is either natural convection or forced convection by means of fans. The heating rate is controlled by the air velocity over the product, the air temperature, the condensation of steam, and the thermal properties of the product. Belt speed can be varied to achieve the required residence time. To some extent, heat is also transferred via radiation from the walls, shelves, and elements (Table 2). Forced convection tunnel ovens may be divided into different sections with different temperature zones if required as in the baking of meat pies. Typical air temperatures range from 150 to 250 °C and heat transfer coefficients between 20 and 90 Wm−2K−1. However, in cooking operations for large joints, low temperatures (75–90 °C) and high humidities are used to minimize weight loss. Long cooking times (up to 16 h) are required in large joints such as beef topsides or hams used for sliced products. Smokehouse cooking, often used for bacon smoking, is a specialist form of hot air cooking.

Steam

Surface heat transfer coefficient (Wm−2 °C−1)

Steam cooking is heating in saturated air, at atmospheric pressure this is at 100 °C, at lower pressures the temperature is below 100 °C, whereas at high pressures the temperature is above 100 °C. Latent heat is given up as the steam condenses at the meat surface, leading to higher heat transfers than are possible with air. However, unless the process is pressurized the surface temperature is restricted to 100 °C, thus browning and other reactions associated with roast meat do not occur. This is not a problem with products that are traditionally boiled, such as gammons. Otherwise steam cooking can be combined with a second-stage radiant or hot air cooking stage to impart the characteristic roast appearance and flavor.

Direct injection of steam can be used for heating meat stews, soups, and similar products. Steam at pressures greater than atmospheric is generally associated with retorting (canning) but it is also employed in the production of pasteurized soups, stews, etc. Higher temperatures lead to faster processing times and can lead to the retention of nutrients that are damaged by long processing.

Hot Water Open top vessels and closed pressurized vessels are used for the cooking of meat containing mixtures that make up pie and pasty fillings, curries, stroganoff, chicken chasseur, Chinese and Italian dishes, etc. An open top vessel is used in many small- and mediumscale operations. The advantage of such systems are low cost, ease of cleaning, and versatility. As they are open topped, they allow components to be conveniently added at different times through the cooking process. The disadvantages in open top vessels are that considerable temperature stratification occurs, with differences of up to 50 °C. The vessels are also energy inefficient with up to 15% of heat lost to the environment via evaporation from the surface. Cooling is a major problem and often the vessel is emptied into a large bin that is allowed to cool in ambient temperatures or in a refrigerated room. Temperatures as high as 65 °C have been recorded in the center of bins after 16 h of ‘cooling’ and during this period the product continues to cook with a consequent deterioration in texture and flavor. Spore-forming bacteria will survive these cooking operations and proliferate at temperatures between 10 and 50 °C. Closed pressurized vessels are water, and sometimes, vacuum-cooled. Numerous designs of vessels are available for a wide field of applications, including atmospheric and super atmospheric pressure operation, with or without agitation with various impeller types such as paddles, turbines, anchors, or propellers, and vessel shapes such as vertical, cylindrical, or hemispherical. Most vessels are of a double-skinned stainless 1000

1000 900 800 700 600

600 500 400 300 200 100 0

50

5 Still air

Moving air Boiling/frying (fan oven) Heat processing method

Figure 1 Typical heat transfer coefficients in cooking operations.

387

Condensing steam

388

Table 2

Cooking of Meat | Heat Processing Methods Radiant heat sources

Type of emitter

Short wavelength Heat lamp Quartz tube Medium wavelength Quartz tube Long wavelength Standard element Ceramic element

Maximum running temperature (°C)

Maximum intensity (kWm−2)

Maximum process temperature (°C)

Radiant heat (%)

Convective heat (%)

2200 2200

10 80

300 600

75 80

25 20

950

60

500

55

45

800 700

40 40

500 400

50 50

50 50

steel design and are heated via steam in the jacket. Direct steam injection into the product is more efficient and reduces processing time. The design and operation of pressurized systems is dependent on: • The optimum time−temperature relationship required during cooking and cooling for the range of products processed. • Overall heat transfer coefficients and their variation with temperature, agitator speed and design, dimensions of vessel, and product characteristics. • Optimum agitator design for each product. Hot water may also be used to cook meats in plastic bags or metal moulds, like hams. Heat transfer is much greater than in air systems and the barriers used prevent weight loss. The products can be cooked in water baths, either batch or continuous, or using hot water sprays.

Hot Fat or Oil Frying Many coated meat products such as rissoles, Kiev's, breaded chicken portions, etc., are deep fat fried. In deep fat frying, heat is transferred via convection from the oil to the product. The heat transfer coefficient has been found to vary during the process. As water from the product is evaporated, turbulence occurs in the fat causing an increased heat transfer rate. The temperature of the oil is usually between 160 and 180 °C, depending on the product being fried. The size of the deep fat fryer may differ from small batch oil baths to large continuous frying baths. In the case of a continuous system, a conveyor belt, often combined with a pushing paddle arrangement, transports the product through the bath. Fat used for frying foods has to fulfill the following demands: • A melting point below 37 °C in order not to cause an unpleasant feeling in the mouth. • A neutral flavor. • Withstand frying temperatures for long periods without foaming due to polymerization and oxidation. • A high smoking temperature. Heated fats and oils rapidly become oxidized and offflavors can readily be picked up by the meat being fried. It is usual practice to replace part of the oil at the end of each production cycle.

Radiant Radiant heating (grilling) primarily involves the infrared portion of the electromagnetic spectrum. Radiant heat transfer is very high and high surface temperatures can be attained, with rapid onset of browning reactions and charring, although not all the heat transfer is radiant (Table 2). For this reason its use is restricted to thin pieces of meat, or in combination with other heating systems (such as conventional air heating, or after steam cooking) to brown the surface of larger products. Electrical elements or flames can be used as the heat source (Table 2). In some cases, flames are used directly to char the surface to impart a barbeque appearance/flavor.

Extrusion Extrusion cooking cannot be applied to conventional meat products but can be used to produce new and novel products. Basic extrusion cookers consist of a screw rotating within a barrel. Meat and other ingredients are carried through the barrel by the screw through a constriction toward the end of the barrel and are combined through mechanical work and heat into a viscous dough. The dough leaves through a die, with accompanying pressure release, cooling, and moisture loss. Heating can be applied directly to the barrel or via steam injection into the ingredients. A significant amount of heating is also provided by the mechanical energy input used to drive the extruder screw; this can account to 50–100% of the total energy input.

Dielectric Dielectric heating is a generic term that includes both microwave and radio frequency heating. It is important to recognize that microwaves and radio frequency radiation are a form of energy, not a form of heat, and are only turned into heat when they interact with a material. When they are intercepted by dielectric materials such as food, they interact with the dielectric material, giving up energy, which results in a temperature increase within the material. There are two main mechanisms in which heat is produced in dielectric materials: ionic polarization and dipole rotation. The major heating mechanism in microwave heating is dipole rotation, in which polar molecules (water being the most common polar material in foods) are rotated by the alternating microwave field

Cooking of Meat | Heat Processing Methods resulting in frictional heat generation. Ionic conductivity is more important during radio frequency heating and occurs when ions in solution move in response to an electric field; the ions are accelerated and collide with each other converting kinetic energy into heat. In many countries, microwave-heating systems are restricted to two frequency bands close to 896 or 2450 MHz. The designs can be separated into resonant cavity systems or waveguide systems. The resonant cavity system is essentially an oven with a conveyor belt passing through it. Absorbent end loads or radio frequency chokes, or both, prevent microwave energy emission from the oven above established limits. The waveguide system is made from a standard waveguide folded back and forth on itself with a slot running through, normal to the fold, through which the conveyor transports the food product. The main reasons for considering the use of microwaves are to accelerate the process, improve quality, reduce costs, and increase yield. Uses in the meat industry of microwave technology have included the tempering of frozen meat blocks, precooking of chicken portions and sliced bacon, burger cooking, and frankfurter processing. Radio frequency has found few meatbased applications, but combination hot air/radio frequency baking ovens have been developed and used for cooking meat pies and pastries.

Ohmic Heating The ohmic heating effect occurs when an electrical current is passed through an electrically conducting product. The idea has been around the last century but within past 20 years new and improved materials and designs have led to commercial systems for continuous flow ohmic heating becoming available. The main interest in this technology is from food manufacturers who wish to aseptically process particulate foods. Conventional methods of heating particulate foods rely on heating of the liquid phase to transfer heat to the solid phase, which necessitates the overprocessing of the liquid phase to ensure that the center of each solid particle receives sufficient heat treatment. This results in reduced quality due to the destruction of flavors and nutrients and mechanical damage to the outside of the particulate. The advantage of ohmic heating in this respect is that liquid and particulate are heated virtually simultaneously without large temperature gradients being produced. The product is heated by internal generation but does not suffer from the temperature nonuniformity commonly associated with microwave heating. The applicability of ohmic heating is dependent on the product being electrically conductive, which is the case with most food preparations as they contain a percentage of free water with dissolved ionic salts. The equipment consists of a column of electrodes with tubular spacers in between, mounted in a near vertical position with the product flow upward. The column is configured so that each heating section has the same electrical impedance; hence the interconnecting tubes increase in length as the product electrical conductivity increases with progressively increasing temperature as it is pumped up the column.

389

Control parameters include the inlet temperature, mass flow rate, outlet temperature, back pressure, and electrical power. Product temperatures of 90–95 °C can be obtained at a pressure of two bar and 120–140 °C at four bar. Systems range from small 5 kW laboratory systems capable of a throughput of 50 kg h−1 to a 600 kW model capable of 6 tons h−1.

Thermal Surface Decontamination Processes There is often no terminal step (such as cooking) to eliminate pathogenic organisms from most of red and white meat until it reaches the consumer. The consumer is relied upon to adequately cook the meat sufficiently to kill any bacteria injurious to health before ingestion. A number of thermal intervention processes have been applied to red meat and poultry carcasses to reduce surface microbial contamination without changing the intrinsic nature of the raw meat.

Hot Water Hot water can be applied as a spray, deluge, or by immersion at temperatures of between 60 and 90 °C. Sprays can be applied manually or preferably via automated spraying cabinets. Deluge systems employ sheets of water and are reported to be more effective than sprays at covering the surface of a carcass. Immersion is effective but difficult to engineer for large carcasses, such as beef carcasses. Hot-water treatments are often reported to initially impart a slight ‘milky’ or ‘ghostly’ appearance to the surface of the carcass; this diminishes on cooling and is virtually undetectable after 24 h storage in chill.

Steam Steam at 100 °C has a substantially higher heat capacity than the same amount of water at that temperature. If steam is allowed to condense onto the surface of meat then it has the ability to rapidly raise the surface temperature of the meat. One very attractive feature of condensing steam is its ability to penetrate cavities and condense on any cold surface. Commercial steam cabinet decontamination systems for beef carcasses are in use in the USA. High-temperature pressurized steam systems and low-pressure vacuum steam systems have been investigated for treating poultry carcasses and cuts of meat at temperatures above and below 100 °C, respectively, but the batch nature of such processes has restricted their development, at present.

Scalding Pork and poultry carcasses are both subjected to a scalding operation during processing. The carcasses are treated with hot water or steam to loosen the hair or feather in the follicle to aid their removal. The time and temperature of the heat treatment are primarily determined by the need for efficient removal of the bristles or feathers by the dehairer/defeatherer. Too low a temperature and the hair/feathers will not be loosened and too high a temperature and the skin will be

390

Cooking of Meat | Heat Processing Methods

cooked and the hair/feathers difficult to remove. The simplest equipment consists of a tank into which the carcass is lowered by a hoist. The water is heated by oil, gas, electricity, or an open steam pipe. Alternatively, vertical cabinets utilizing hotwater sprays or steam can be used. Temperatures between 58 and 62 are normally used for 5–6 min for pig carcasses, whereas temperatures of 50–51 °C for 3.5 min are employed for ‘soft’ scalded chicken carcasses destined for chilling, or 56– 58 °C for 2–2.5 min for ‘hard’ scalded carcasses destined for freezing.

Singeing Residual hair left on a pig carcass after the scalding/dehairing process is burnt by singeing. The carcass is subjected to an exposed high temperature flame either with a hand-held gas torch or in automated systems that transport the pig into a furnace running at 1000 °C for as little as 6 s. During singeing, any water remaining on the surface of the carcass and in the outer layers of the skin evaporates. The heat denatures the collagen fibers in the epidermis and the skin shrinks. Any charred hair and surface dirt are removed in a final polishing/ scrapping operation.

Further Reading Anon, 2006. CFA Best Practice Guidelines for the Production of Chilled Foods, fourth ed. London: Chilled Food Association. Blackburn, C.d.W., 2009. Foodborne Pathogens. Cambridge, UK: Woodhead Publishing Ltd. Fellows, P.J., 2009. Food Processing Technology: Principles and Practice. Cambridge, UK: Woodhead Publishing limited. Gould, G.W., 1989. Mechanism of Action of Food Preservation Procedures. Barking, UK: Elsevier Science Publishers Ltd. Høyem, T., Kvåle, O., 1977. Physical, Chemical, and Biological Changes in Food Caused by Thermal Processing. London: Applied Science Publishers Limited. Hui, Y.H., 2012. Handbook of Meat and Meat Processing, second ed. Boca Raton, US: CRC Press. James, C., James, S.J., 1997. Meat Decontamination − The State of the Art. Bristol, UK: FRPERC, University of Bristol. Knipe, C.L., Rust, R.E., 2009. Thermal Processing of Ready-to-Eat Meat Products. New York: Wiley-Blackwell. Lawrie, R.A., Ledward, D.A., 2006. Lawrie's Meat Science. Cambridge, UK: Woodhead Publishing limited ISBN 1 84569 159 8. Sandeep, K.P., 2011. Thermal Processing of Foods: Control and Automation. New York: Wiley-Blackwell. Simpson, R., 2009. Engineering Aspects of Thermal Food Processing. Boca Raton, FL: CRC Press. Sun, D.W., 2012. Thermal Food Processing: New Technologies and Quality Issues, second ed. Boca Raton, FL: CRC Press. Toldrá, F., 2010. Handbook of Meat Processing. Ames, IA: Wiley-Blackwell.

Relevant Websites See also: Canning. Chemical and Physical Characteristics of Meat: Chemical Composition; Palatability. Cooking of Meat: Flavor Development; Maillard Reaction and Browning; Physics and Chemistry; Warmed-Over Flavor. Extrusion Technology. Microbiological Safety of Meat: Clostridium botulinum and Botulism; Listeria monocytogenes. Processing Equipment: Smoking and Cooking Equipment

http://www.ecff.net/ European Chilled Food Federation. http://www.fao.org/ Food and Agriculture Organization of the United Nations. http://www.chilledfood.org/ UK Chilled Food Association.

Maillard Reaction and Browning F Shahidi, Memorial University of Newfoundland, St. John’s, NL, Canada AGP Samaranayaka, POS Bio-Sciences, Saskatoon, SK, Canada RB Pegg, University of Georgia, Athens, GA, USA r 2014 Elsevier Ltd. All rights reserved. This article is a revision of the previous edition article by F Shahidi, AGP Samaranayaka, RB Pegg, volume 2, pp 578–592, © 2004 Elsevier Ltd.

Glossary Heterocyclic compounds The cyclic compounds generated during Maillard reaction that contain nitrogen, oxygen, or sulfur atoms or their combination in the ring. Lipid oxidation aldehydes The aldehydes generated from oxidation of lipids, including phospholipids. Maillard browning The nonenzymatic Maillard reaction that leads to the formation of brown colors.

Introduction Flavor is an important aspect of food quality and in the case of cooked meats, it determines their overall acceptability. Raw meat has little or no aroma and only a blood-like taste. The flavor of meat is thermally derived, and each type of cooked meat has a characteristic flavor based on the animal, presence of other ingredients, and the type of heat processing (i.e., roasting, grilling, and stewing) employed. The nonvolatile taste active compounds and the volatile aroma constituents generated from meat during thermal processing contribute mainly to the specific cooked meat flavor. Other sensations such as mouth feel, texture, and juiciness also affect the overall flavor attributes of cooked meat. Yet, it is the flavor volatiles of cooked meat that determine the product’s aroma and have a profound effect on sensory acceptability even before the meat product is consumed. Both water-soluble components (e.g., amino acids, peptides, carbohydrates, nucleotides, thiamine) and lipids in raw meat contribute to the development of meat flavor. The main reactions that occur during cooking and generate aroma volatiles are the Maillard reaction (i.e., a nonenzymatic browning reaction between amino acids and reducing sugars), the breakdown and oxidation of lipid constituents, and the degradation of vitamins, particularly thiamine. Intermediary products from these primary reactions can function as precursors and react with other degradation products of meat, depending on the cooking conditions employed, to form a large number of volatiles responsible for the characteristic flavor of cooked meat. To date, more than a thousand volatile compounds have been identified from cooked meat systems; Figure 1 illustrates some important classes of volatile compounds that have been identified. The occurrence of the Maillard reaction is very important when meat is cooked, because it generates a large number of compounds that contribute to meat flavor. Most flavor compounds of cooked meats with roasted, boiled, and meaty notes are generated via the Maillard reaction and are generally N-, S-, O-heterocyclics. The Maillard reaction is also associated with

Encyclopedia of Meat Sciences, Volume 1

Maillard reaction A nonenzymatic reaction occurring on heat processing of meat between reducing sugars and amino group of free amino acids, peptides, and proteins. Meat flavor Is affected by both volatile compounds responsible for the aroma of products and the nonvolatiles responsible for taste effects.

brown color formation, and for this reason is often referred to as the ‘browning’ or ‘nonenzymatic browning’ reaction. The brown pigments, known as melanoidins, contain variable amounts of nitrogen and have differing molecular weights and solubilities in water. The dark brown color on the surface of roasted meats is a key factor in consumers’ acceptance of these products. Several other changes in the characteristics of cooked meat may also result from Maillard-type reactions and include the production of bioactive compounds with beneficial (i.e., compounds with antioxidant properties) or toxic (e.g., imidazoles) effects, a loss of nutritional quality (especially of proteins), and modification to the product’s texture.

The Maillard Reaction In 1912 at the University of Nancy, France, Louis Camille Maillard first observed the generation of different odors and the formation of brown colored pigments after heating amino acids in the presence of various sugars. The term ‘Maillard reaction’ was thereafter used to describe the complex series of chemical reactions between carbonyl compounds, especially those of reducing sugars, and primary or secondary amino groups in foods. Browning in most foods is a combined result of the Maillard reaction and caramelization and depends on the product formulation and processing conditions. The ingredients present affect the formation of Maillard reaction products (MRP). In this connection, protein hydrolysates obtained by enzymatic hydrolysis of mechanically deboned chicken meat and the resultant MRPs produced at 90 °C and 100 °C possessed good antioxidant activity and also positively affected the texture and sensory properties of Cantonese sausages. In another study, honey-lysine MRP had an antioxidant effect in linoleic acid emulsion and when honey was added to turkey meat, it enhanced antioxidant properties of the meat as reflected in its thiobarbituric acid reactive substances values. Hence, ingredients present can affect the flavor quality of cooked muscle food products.

doi:10.1016/B978-0-12-384731-7.00130-6

391

392

Cooking of Meat | Maillard Reaction and Browning

Lipid-derived volatiles

O

O R

R C Alkanals

OH

Alkanones

O

O

R

-Lactones

R CH2 OH

C

R′

H

R

O R

C

Alkanoic acids

O

Alkanols

O

O

-Lactones

R

Alkylfurans

Volatiles from water-soluble precursors

O

R

R

O

Furanones

R

R

R

N

R

R

N

R

N

Pyrazines

R

S R

S

Thiazoles

SH

R

Thiophenes

R

R

S

O

R

SH

R S

R

S

S R

Alkyl sulphides

R

N

Oxazoles

S

R

Trithiolanes

R Alkanethiols

Pyrroles

S S

R

R

N

Pyridines

N S

R

R

Trithianes

O Methylfuranthiol

R

S

Alkyl disulphides

Figure 1 Some classes of volatile compounds produced during the cooking of meat. Reproduced from Shahidi, F., Rubin, L.J., D'Souza, L.A., 1986. Meat flavour volatiles: A review of the composition, techniques, analyses and sensory evaluation. CRC Critical Reviews in Food Science and Nutrition 24, 141–243 and Mottram, D.S., 1998. Flavour formation in meat and meat products: A review. Food Chemistry 62, 415–424.

The actual products formed from the Maillard reaction in biological systems depend on the temperature and time (duration) of cooking, water activity/moisture content, pH, as well as the nature and concentration of the reactants involved. An increase in the formation of brown-colored pigments (i.e., melanoidins) and low-molecular weight flavor compounds in cooked foods significantly correlated with higher cooking temperatures. The optimum rate for the Maillard reaction occurs at a water activity of 0.65–0.75. In other words, the Maillard reaction proceeds more readily at low moisture levels, and the flavor compounds generated are associated mostly with the exterior areas of meat, which have been dehydrated during cooking.

Early Stages of the Maillard Reaction The initial stages of the Maillard reaction have been well studied. The mechanism proposed by Hodge (1953) the socalled Hodge-scheme to describe the initial stages of the reaction still provides the basis for our understanding of this reaction. The beginning reactions are depicted in Figure 2. Some researchers have suggested that the cyclic pyranose and

furanose conformations of sugars are more likely to be involved in the reactions, as they are most abundant in aqueous solution. To initiate the Maillard reaction, a carbonyl group from the open chain of an aldose sugar reacts reversibly with an amino group of an amino acid, peptide, protein, or other compound possessing a primary or a secondary amino moiety, followed by water elimination leading to an intermediate imine, which cyclizes to produce a glycosylamine (i.e., N-glycoside). The Schiff base formed from a hexose and an amino compound may not necessarily cyclize to the glycosylamine and rearrange to form the key intermediate, an 1,2-enaminol, in this primary step of the Maillard reaction. The 1,2-enaminol has three possibilities in which to further react. One possibility is that, it undergoes Amadori rearrangement to yield 1-amino-1-deoxyketose (i.e., an Amadori compound). At higher pH, however, 2,3-enolization is favored and β-elimination of the amine affords a 1-deoxydicarbonyl compound (i.e., 1-deoxyosone). The reaction between ketosugars (e.g., fructose) and amines follows a similar sequence of reactions to form an N-ketosylamine, which undergoes a Heyns rearrangement to give a 2-amino-2-deoxyaldose. A second possibility is that, at lower pH, 1,2-enolization of the Amadori product occurs, and the

Cooking of Meat | Maillard Reaction and Browning

OH

OH HO

R

R-NH2

OH

H2O

OH

HO

OH

R

O

OH

OH

HO

Cyclization

N

OH

OH

R

H2O

O

OH

NH

O

R Glycosylamine

Shiff base

HO

OH

R

R

Carbohydrate

393

HO

OH

Oxidation R

N

OH

HO

−H2O

R

NH

OH

OH

R 1,2-Eneaminol (enol form)

R

R-NH2

N R

H2O R-NH2

OH O

HO

R

HO

1,2-Enolization pH ≤ 5.0

OH

O

R

Glucosone

OH OH

O

OH

3-Deoxyosone

OH HO

O

HO

O

2,3-Enolization

pH ≥ 7.0

OH HO

O

OH

HO

OH

NH R

O

R

CH3 R

OH

NH R

(Cyclic form)

(Keto form)

R

OH

NH R

R

O

R-NH2 1-Deoxyosone

N-1-Amino-1-deoxy-2-ketose (Amadori compound) Figure 2 Primary reaction pathways of the Maillard reaction. Modified from Schieberle, P., Hofmann, T., 2002. New results on the formation of important Maillard aroma compounds. In: Swift, K.A.D. (Ed.), Advances in Flavour and Fragrances: From the Sensation to the Synthesis. Cambridge, UK: Special publications of the Royal Society of Chemistry, pp. 163–177, with permission from RSC.

1,2-enaminol formed can lose a molecule of water to yield 3-deoxyosone after hydrolysis of the intermediary α-oxoimine (Figure 2). Thirdly, oxidation of the 1,2-enaminol may take place generating an α-oxoimine, which after hydrolysis forms a hexosone. The reaction intermediates so formed are thermally unstable and can degrade to a number of flavor compounds (i.e., N-, S-, O-heterocyclics) by the so-called advanced Maillard reaction during further heat treatment. The types of reaction that can take place during the degradation of formed reductones and dehydroreductones include dehydration reactions while maintaining the carbohydrate skeleton, retroaldol reactions leading to fission products, aldol-type reactions of generated fission products, substitution of oxygen-containing

compounds by nitrogen and sulfur atoms, redox reactions, and Strecker reactions. Some of the reaction pathways leading to the formation of key intermediary flavor compounds in meat are illustrated in Figures 3 and 4. These compounds can react with other Maillard reaction degradation products as well as with other constituents of the meat matrix (e.g., lipid oxidation products) to form characteristic flavor compounds in cooked meats. Dehydration and cyclization of 1-deoxyosone lead to the formation of 4-hydroxy-5-methyl-3(2H)-furanone from pentoses and 4-hydroxy-2,5-dimethyl-3(2H)-furanone (furaneol) from hexoses. Maltol (3-hydroxy-2-methyl-4H-pyran-4-one), 5hydroxy-5,6-dihydromaltol, isomaltol [1-(3-hydroxy-2-furanyl)ethanone], and cyclotene are other important dehydration

394

Cooking of Meat | Maillard Reaction and Browning

O

HO

4-Hydroxy-5-methyl-3(2H)-furanone (R = H) HO

CH3

O OH

C O C O

−H2O

CH3

H C OH

O

H C OH

O

Isomaltol (R = H)

O OH

R

Maltol (R = H)

1-Deoxyosone CH3 O H3C

CH3

CHO

C O C OH

O

O

Fission H3C

C OH H C OH

Pyruvaldehyde

Diacetyl

CH3 O

Hydroxyacetone

R Reductone

H3C

CH2OH

H C O C O C H

2-Furfural (R = H)

−H2O R

C H

O

CHO

H C OH R 3-Deoxyosone Figure 3 Degradation of Maillard reaction intermediates to form important meat flavor precursors. Reproduced from Bailey, M.E., 1998. Maillard reactions and meat flavour development. In: Shahidi, F. (Ed.), Flavour of Meat, Meat Products and Seafoods. London: Blackie Academic and Professional, pp. 267–289, with permission from Blackie Academic.

products of hexoses (Figure 4). Cyclotene can also be formed by condensation of hydroxyacetone. Degradation of 3-deoxyosones produces 5-hydroxymethyl-2-furfural from hexoses and 2furfural from pentoses. These furfural derivatives react readily with ammonia and hydrogen sulfide to give many heterocyclic flavor compounds in cooked meats. Retro-aldol (fission) reactions of 1-deoxyreductone (i.e., an equilibrium product of 1-deoxyosone) in a basic medium (pH45) can lead to the formation of very reactive carbonyl compounds such as pyruvaldehyde, diacetyl, dihydroxyacetone, glyoxal and hydroxyacetal, and acetic acid. These compounds participate in Strecker reactions to produce meat flavor compounds.

the formation of an aldehyde, often called a Strecker aldehyde, which contains one less carbon atom than the original amino acid and carbon dioxide; meanwhile, the dicarbonyl, originating from saccharides, is converted into an α-aminoketone or aminoalcohol (Figure 5). Aminoketones are important intermediates in the formation of several classes of heterocyclic compounds such as pyrazines, oxazoles, and thiazoles; all of which are powerful aroma constituents (Figure 1). If the amino acid is cysteine, the Strecker reaction leads to the formation of ammonia, hydrogen sulfide, and acetaldehyde; these three compounds are very important intermediates in the formation of different classes of flavor compounds in cooked meat. Sulfur compounds, derived from cysteine and ribose, are particularly significant for the generation of aroma notes characteristic of cooked meat.

Strecker Reaction The reaction between amino acids and α-dicarbonyl compounds (e.g., deoxyosones), which occur as intermediary or end products of other decomposition reactions of the Maillard reaction (e.g., diacetyl, pyruvaldehyde, hydroxyacetone), is one of the most important interactions relating to meat flavor generation. This reaction, termed the Strecker reaction, leads to

Later Stages of the Maillard Reaction As aforementioned, a number of oxygenated sugar degradation products are formed during the initial stages of the Maillard reaction in meat and undergo further interactions at the elevated temperatures associated with cooking. The

Cooking of Meat | Maillard Reaction and Browning

OH

O

HO

395

OH

HO

O

HO O

CH3

OH O

HOH2C

C CH 3 3,6-Condensate

OH O

OH O

1-Deoxyhexosone

CH3

2,6-Condensate

−2H2O O

OH

OH

OH O

HO O CH3

OH O

H3C

C

O

CH3

OH O

CH3

Isomaltol −H2O

−H2O

−2H2O

O O

OH

HO

OH

O OH

H3C

O Furaneol

CH3 O 5-Hydroxy-5,6dihydromaltol

CH3

CH3 O Maltol

CH3

OH O Cyclotene Figure 4 Formation of specific meat flavor intermediates by cyclization and dehydration of 1-deoxyhexosones. Reproduced from Bailey, M.E., 1998. Maillard reactions and meat flavour development. In: Shahidi, F. (Ed.), Flavour of Meat, Meat Products and Seafoods. London: Blackie Academic and Professional, pp. 267–289, with permission from Blackie Academic.

O

R +

O

R′

R

R′

−H2O

NH2

N

O

COOH

O H

O

R R

−CO2

O

R

H2S + NH3 + CH3CHO + O

R

For cysteine R′ = HS.CH2− R′ + 2H2O

N

H

O

R R

R′ CHO

Strecker aldehyde

H2N

R

O

R

+

Figure 5 Strecker reaction of amino acids. Reproduced from Mottram, D.S., 1994. Flavor compounds formed during the Maillard reaction. In: Parliament, T.H., Morello, M.J., McGorrin, R.J. (Eds.), Thermally Generated Flavours. Maillard, Microwave and Extrusion Processes. ACS Symposium Series 543. Washington, DC: American Chemical Society, pp. 104–126, with permission from ACS.

Strecker reaction also leads to the production of many reactive compounds such as Strecker aldehydes, ammonia, and hydrogen sulfide. Many of these possess aroma or taste notes, as already commented upon, but they are also crucial intermediates for further flavor-forming reactions in meat during later stages of the Maillard reaction.

Meat Flavor Compounds from Maillard Reaction Most of the flavor compounds generated via the Maillard reaction are N-, S-, O-heterocyclics and other sulfur-containing compounds that give roasted, boiled, and meaty aromas to cooked meat. These compounds contribute significantly to the

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Cooking of Meat | Maillard Reaction and Browning

Formation of alkyl pyrazines

R1 R2

C C

−2H2O

O

+

Amino acids

R1

N

R2

N

R2

[O]

O

R1

Alkylpyrazines Formation of cyclic pyrazines

R1 R2

C C

O

R3

+

N

R1

Amino acids OH

O

O Cyclotene

−2H2O [O]

N

R2

R3 Cyclopentapyrazines

Figure 6 Reaction pathways proposed for the formation of pyrazines. Reproduced from Bailey, M.E., 1998. Maillard reactions and meat flavour development. In: Shahidi, F. (Ed.), Flavour of Meat, Meat Products and Seafoods. London: Blackie Academic and Professional, pp. 267–289, with permission from Blackie Academic.

overall aroma profile of cooked meat; they include furans, furanones, pyrazines, pyrroles, thiophenes, thiazoles (thiazolines), imidazoles, pyridines, oxazoles, cyclic ethylene sulfides, alkyl sulfides, and disulfides (Figure 1).

Oxygen-Containing Compounds Early stages of the Maillard reaction produce oxygenated furans and pyrans, such as furfural, 5-methylfurfural, 2-acetylfuran, maltol, isomaltol, and furanones like 4-hydroxy-5-methyl-3 (2H)-furanone (norfuraneol), and 4-hydroxy-2,5-dimethyl-3 (2H)-furanone (furaneol) (Figures 3 and 4). Usually, molecules having a planar enol-carbonyl structure in a cyclic dicarbonyl compound originate from sugars and elicit a caramel-like aroma. Most of the reaction products (e.g., maltol, ethylmaltol, dihydromaltol, 4-hydroxy-5-methyl-3(2H)-furanone, and norfuraneol) containing this structural element contribute to the ‘caramel-like’ odor of cooked meats. As previously mentioned, these compounds are also important intermediates in the formation of other N- and S-containing meat flavor volatiles during thermal processing. For example, sugar degradation products like maltol, isomaltol, 4-hydroxy-5-methyl-3(2H)furanone, furaneol, and cyclotene can exchange oxygen in the ring with nitrogen and sulfur to produce other flavor compounds.

Nitrogen-Containing Compounds Pyrazines Pyrazines have been found in all meat species following cooking and constitute a major class of volatiles formed via the Maillard reaction. The nature and quantity of pyrazines generated during thermal processing are a function of the reaction conditions employed, such as moisture content, pH, temperature, and the duration (time) of cooking. Several mechanisms have been proposed for pyrazine formation by the Maillard reaction: one important route is the condensation of

α-dicarbonyl compounds formed from the Strecker reaction with amino compounds to give alkylpyrazines (Figure 6). Two other classes of compounds, mainly bicyclic products, 6,7-dihydro-5(H)-cyclopentapyrazines and pyrrolopyrazines, have also been reported in meat volatiles. Cyclopentapyrazines can be formed from the condensation of cyclic ketones such as cyclotene (Figure 6). The alkylpyrazines generally have nutty and roasted aromas, whereas cyclopentapyrazines have roasted, grilled, and species-related flavor notes of roasted meat. The pyrrolopyrazines have only been reported for meat. Recent evidence indicates that 3-deoxyglucosone is a chief precursor for pyrazine formation by retro-aldolization and 2,4-scission to yield pyruvaldehyde. Pyruvaldehyde is involved in the Strecker reaction to give dimethylpyrazine. Formation of 48 pyrazines from beef, 36 from pork, and 16 from lamb have been documented. These are extremely important constituents of meat cooked at high temperatures and contribute mainly to the flavor of roasted meat. Pyrazines account for 77% of the total volatiles found in well-done grilled pork.

Oxazoles and oxazolines Several oxazoles have been identified in cooked meats, and these possess green and vegetable-like aroma characteristics. The compound 2,4,5-trimethyl-3-oxazoline, with a woody, musty, and green note, has also been detected in boiled beef. However, contribution of oxazoles and oxazolines to the overall aroma of meat is not as significant as that of sulfurcontaining compounds such as thiazoles and thiazolines, which possess closely related chemical structures.

Sulfur-Containing Compounds Sulfur compounds, both aliphatic and heterocyclic, are among the most important volatiles formed during meat processing. Most occur at low concentrations, but their very low odor thresholds make them potent aroma compounds giving sulfurous, onion-like, and meaty aromas to cooked meat

Cooking of Meat | Maillard Reaction and Browning R2

O

R3

OH

H2S

H

O

R3

SH

R2

O NH2

R3

HN

NH3

O

R2

R′

S

R′

R′

H

R2

R2 R3

N

N S

Alkylthiazole

R1

R3

S

R1

Alkyl-3-thiazoline

Figure 7 Route for the formation of thiazolines and thiazoles in the Maillard reaction from the reaction of hydroxyketones and aldehydes with ammonia and hydrogen sulfide. Reproduced from Mottram, D.S., 1998. Flavour formation in meat and meat products: A review. Food Chemistry 62, 415–424.

products. Hydrogen sulfide, produced from cysteine by hydrolysis or via the Strecker reaction, is an essential precursor in the formation of many sulfur-containing aroma compounds in meat during thermal processing. The cooking method employed has a significant effect on the generation of sulfurous compounds. For example, more aliphatic thiols, sulfides, and disulfides have been reported in boiled beef compared to those of roast beef. Heterocyclic compounds with 1, 2, or 3 sulfur atoms in their 5- and 6membered rings (e.g., thiophenes, trithilanes, trithianes) are formed in greater amounts in boiled meat than in roasted meat.

Thiazoles and thiazolines These compounds are important constituents of roasted or fried meat, and their content increases with higher cooking temperatures. Most thiazoles present in meat are alkyl substituted, and their aroma depends on the nature and the number of alkyl moieties attached. A number of the di- and tri-alkyl derivatives formed in meat have been reported to possess roasted and meaty aroma characteristics. Some acetylsubstituted thiazoles and thiazolines have also been found in cooked meats. One possible route for the formation of thiazoles and thiazolines is via the Maillard reaction, and this involves the action of ammonia and hydrogen sulfide in the presence of α-carbonyls, dicarbonyls, or hydroxyketones (Figure 7) derived from the Strecker reaction of amino acids in heated foods. However, lipid-derived aldehydes can also participate in this reaction during cooking and, in fact, long-chain trialkylthiazoles have been identified in the aromagrams of roast beef and fried chicken.

Thiophenes Perhaps the most important flavor compounds arising from the Maillard reaction are the thiophenes and furans with methyl or sulfur groups at 1, 2, or 5 positions. These compounds give desirable ‘meaty’ aroma to cooked meat. Furans and

397

thiophenes with a thiol group at the 3-position also possess a strong meaty-like aroma and have very low odor threshold values. There are a number of possible routes for the formation of thiophenes, involving the reaction of a sulfur compound derived from sulfur-containing amino acids (e.g., cysteine, cystine, methionine) or thiamine, with intermediary sugar degradation products from the Maillard reaction, such as deoxyosones. Another pathway has also been proposed for the formation of long-chain 2-alkylthiophenes from reactions involving hydrogen sulfide and the 2,4-alkadienals derived from the degradation of lipids.

Polysulfur heterocyclics A number of polysulfur heterocyclics have been found in meat, and the formation of these compounds is very important for the desirable meaty aroma in cooked meats. Seventy-eight compounds having meat-like aromas have been reported, of which 65 are heterocyclic sulfur compounds and seven are sulfur-containing aliphatic compounds. The remaining six are nonsulfur-containing heterocyclics. The mechanisms of formation of a number of these cyclic-sulfur compounds in the aroma of cooked beef via the Maillard reaction or thermal degradation of thiamine have been reported. Acetaldehyde, formed by the Strecker reaction of alanine during thermal processing, and other aldehydes can react with precursors such as hydrogen sulfide, ammonia, and methanethiol to yield a large number of heterocyclic and straight chain polysulfur compounds in meat (Figure 8). Under oxidative conditions, dialkyltrithiolanes are formed from bis(1-mercaptoethyl)sulfide, whereas at low pH trialkyltrithianes are produced (Figure 8). At elevated temperatures, bis(1-mercaptoethyl)sulfide isomerizes to trisulfides and leads to the formation of di- and tetrasulfides. Dithiazines and thiadiazines are generated in the presence of ammonia (Figure 8). Thus, the formation of these compounds in cooked meats depends on the reaction conditions (i.e., acidity and temperature of thermal processing) and the types of Strecker reaction products available for each of the reactions to proceed.

Sulfur compounds from furan-like components As aforementioned, furans with a thiol group in the 3position, and related disulfides, possess strong meat-like aromas with very low odor threshold values. The presence of 2-methyl-3-(methylthio)-furan and 2-methyl-3-(methyldithio)furan in cooked beef has been reported; these compounds have odor thresholds of 50- and 10 parts-per-billion, respectively. In addition, 2-methyl-3-furanthiol and the corresponding disulfide, bis-(2-methyl-3-furanyl)disulfide (odor threshold of 0.02 ng kg−1), have been identified as major contributors to the meaty aroma of cooked beef. In meat, 4-hydroxy-5-methyl3(2H)-furanone, formed via dephosphorylation and dehydration of ribose phosphate (from ribonucleotides), reacts with hydrogen sulfide to yield the above mentioned meat flavor character impact compounds (Figure 9). Some other furan-like sulfur compounds (Figure 10), apart from those described above, have also been identified in cooked meats. Oxidation of thiols formed via interaction of hydrogen sulfide with dicarbonyls, furanones, and furfurals (i.e., prominent products of the Maillard reaction) may provide other routes in the formation of furan sulfides and disulfides.

398

Cooking of Meat | Maillard Reaction and Browning

S

SH

1-Methylthio-1-ethanethiol

CH3SH SH CH3CHO

SH

S

S

Acetaldehyde +

H

NH3 CH3CHO

CH3CHO S

S

[O]

H2S

Heat

S 3,5-Dimethyl-1,2,4-trithiolane

S

S S S Diethyltrisulphide

S 2,4,6-Trimethyl1,3,5-trithiane

S

S

N H 5,6-Dihydro-2,4,6-trimethyl1,3,5-dithiazine

+

S S S S Diethyltetrasulphide

+ HN

NH

S S Diethyldisulphide

S 5,6-Dihydro-2,4,6-trimethyl1,3,5-thiadiazine Figure 8 Formation of some sulfur-containing aroma compounds from reaction of acetaldehyde, hydrogen sulfide, ammonia, and methanethiol. Modified from Mottram, D.S., 1994. Flavor compounds formed during the Maillard reaction. In: Parliament, T.H., Morello, M.J., McGorrin, R.J. (Eds.), Thermally Generated Flavours. Maillard, Microwave and Extrusion Processes. ACS Symposium Series 543. Washington, DC: American Chemical Society, pp. 104–126, with permission from ACS.

H

O

CH2OPO3H2

O

OH

H

H

OH

OH

H O

OH OH

O

O

Ribose phosphate

S

O

OH

H2O

−H2O

S

SH

[O] O

O

O H2S

S

CH3SH O

O

Figure 9 Route for the formation of 2-methyl-3-furanthiol, bis-(2-methyl-3-furanyl) disulfide, and 2-methyl-3-(methylthio)-furan from ribose phosphate. Reproduced from Mottram, D.S., 1998. Flavour formation in meat and meat products: A review. Food Chemistry 62, 415–424.

Cyclotene (2-hydroxy-3-methylcyclopent-2-enone), another product of the Maillard reaction, formed from 5-hydroxy-5,6dihydromaltol (Figure 4) and from the condensation of hydroxyacetone, can react with ammonia and hydrogen sulfide to generate volatile compounds with meaty aromas (e.g., 1,2,4-trithiolane, 5-trithiane, and 1,2,4,6-tetrathiepane) and a roasted beefy note (e.g., 2-methylcyclopentanone and 3methylcyclopentanone). Isomaltol is also an important precursor of the heterocyclic compounds related to cooked meat flavor.

Meat Flavor Compounds from Lipid−Maillard Interactions Both saturated and unsaturated aldehydes formed via autoxidation of lipids are among the major contributors to the volatile profile of cooked meats. At the same time, these aldehydes can participate in the Maillard reaction at both the initial and later stages during thermal processing of meat. Volatile compounds such as pyridines, pyrazines, thiophenes, thiazoles, and oxazoles with alkyl substituents are formed.

Cooking of Meat | Maillard Reaction and Browning

O

SH

O

SH 3-Mercapto2-butanone

399

SH 2-Mercapto3-pentanone

SH O 2-Furanmethanethiol

O

2-Methyl-3-furanthiol

Sn−CH3

S

S

Sn−CH3 O n = 1,2 or 3 2-Methyl-3-(methylthio)furan and dithio and trithio homologue

O

O

O

n = 2 or 3 2-[(Methylthio)methyl]furan and trithio homologue

bis-(2-Methyl-3-furanyl)disulphide

O S

S

S O

O 2-Methyl-3-[(2-furanylmethyl)dithio]furan

S S O O bis-(2-Furanylmethyl)disulphide

O

O 2-[(2-Methyl-3-furanyl)dithio]3-pentanone

O

O S S

S

S S

R

O

R = CH3 or C2H5

R

R = CH3 or C2H5

1-[(2-Furanylmethyl)dithio]-2-propanone and -2-butanone

2-[(2-Furanylmethyl)dithio]-3-butanone and -3-pentanone

Figure 10 Some thiols, sulfides, and disulfides found in the volatiles of cooked meat. Reproduced from MacLeod, G., Ames, J.M., 1986. 2-Methyl-3-(methylthio)furan: A meat character impact aroma compound identified from cooked beef. Chemistry and Industry (London) 50, 175–176; Gasser, U., Grosch, W., 1988. Identification of volatile flavor compounds with high aroma values from cooked beef. Zeitschrift fuer Lebensmittel Untersuchung und Forschung 186, 489–494; Farmer, L.J., Patterson, R.L.S., 1991. Compounds contributing to meat flavour. Food Chemistry 40, 201–205; Madruga, M.S., 1994. Studies on some factors affecting meat flavour formation. Ph.D Thesis, The University of Reading, UK; and Madruga, M.S., Mottram, D.S., 1995. The effect of pH on the formation of Maillard-derived aroma volatiles using a cooked meat system. Journal of the Science of Food and Agriculture 68, 305–310.

R1

R1

R2

N

N

S

CnH2n−1

R1 = H, CH3 or C2H5 R2 = CH3 or C2H5 n = 3−9, 15

R2

S

CnH2n−1

R1 and R2 = CH3 or C2H5 n = 4−8, 15

Figure 11 Alkyl-3-thiazolines and alkylthiazoles found in cooked beef and lamb. Reproduced from Mottram, D.S., Elmore, J.S., 2002. Novel sulfur compounds from lipid−Maillard interactions in cooked meat. In: Reineccius, G.A., Reineccius, T.A. (Eds.), Heteroatomic Aroma Compounds. ACS Symposium Series 826. Washington, DC: American Chemical Society, pp. 93–101, with permission from ACS.

A number of thiazoles with C4−C8n-alkyl substituents in the 2-position have been reported in roast beef and fried chicken. Several other alkylthiazoles with longer 2-alkyl chains of C13−C15 have been identified in the volatiles of heated beef and chicken, with the highest concentrations reported in beef heart muscle. Recently, a series of alkylthiazoles and alkyl3-thiazolines were isolated from the volatiles of cooked beef and lamb (Figure 11); the amounts formed were greater in pressure-cooked meat than in grilled meat. Furthermore, the

number and concentration of these compounds were much higher in meat from animals fed a linseed and fish oil diet than in the control diet devoid of them. Lipid-derived aldehydes can participate in the formation of long-chain 2-alkylthiazoles in heated meats. Reactions of aldehydes, hydroxyketones, ammonia, and hydrogen sulfide with one another, as illustrated in Figure 7, have already been discussed. The compound 2-pentylpyridine has been identified in all major meat species; a likely route of its formation is via the reaction of E,E-2,4-decadienal with ammonia (Figure 12). Similar types of reactions between 2,4-alkadienals and hydrogen sulfide may be responsible for the formation of 2-alkylthiophenes and 2-alkyl-(2H)-thiapyrans (Figure 12). Butyl- and pentyl-substituted pyrazines have been identified in cooked meats. The probable mechanism for their formation is via the reaction of pentanal or hexanal with a dihydropyrazine, formed by the condensation of two aminoketone molecules (Figure 13). Pentanal and hexanal, which are breakdown products of linoleic acid (18:2n6), also appear to be involved in the formation of 5-butyl-3-methyl-1,2,4-trithiolane and its 5-pentyl homologue. Both trithiolanes have been isolated from the volatiles of fried chicken and pork. Volatile compounds derived from lipid-Maillard interactions of meat possess weak odor intensities (i.e., weak fatty, fried, and garlic-like notes) and high odor thresholds;

Cooking of Meat | Maillard Reaction and Browning

400

consequently, they may not contribute directly to the aroma of cooked meat. However, interactions between lipid degradation and MRP during thermal processing may modify the aroma compounds generated via the Maillard reaction and by lipid degradation and, therefore, have an indirect impact on the aroma profile of cooked meat. In particular, phospholipids and their degradation products inhibit reactions involved in

the formation of heterocyclic aroma compounds via the Maillard reaction. Thus, the generation of sulfur-containing heterocyclics during thermal processing of meat may be curbed by this inhibition. This interaction may help to maintain the level of key sulfur compounds at their optimum concentrations in cooked products.

Maillard Browning O

Besides aroma, the brown color formation due to the Maillard reaction (i.e., nonenzymatic browning) is a key factor in the overall acceptability of thermally processed foods such as roasted meat and coffee. Little is known, however, about the chromophores responsible and the reaction mechanisms leading to the formation of these brown color compounds from carbohydrates and amino acids. From studying reducing sugar/amino acid reaction mixtures, the chromophores identified as ‘browning agents’ can be divided into two classes: lowmolecular weight colored compounds and high-molecular weight melanoidins. Model experiments indicate that condensation reactions between methylene-active intermediates (e.g., 4-hydroxy-5-methyl-3(2H)-furanone) and reactive carbonyl compounds (e.g., furan-2-aldehyde, acetaldehyde, acetone, pyrrolaldehydes, or 2-oxopropanal) generated during the Maillard reaction are the dominant reaction in nonenzymatic browning and aid in the formation of low-molecular weight colored compounds (Figure 14). Besides the classical reaction pathway proposed by Hodge (Figure 2), model experiments have shown another reaction pathway leading to the formation of color in very early stages of the Maillard reaction and before Amadori rearrangement. The proposed mechanism involves cleavage of the sugar molecule with the production of glycolaldehyde imine; this product dimerizes and oxidizes to form a 1,4-dialkylpyrazinium radical cation (Figure 15) as an important intermediate. Early stages of browning in foods and beverages may be a result of this phenomenon. Although the exact structures of high-molecular weight melanoidins have not been elucidated, it has been found that such compounds can be generated during thermal processing

H NH3

C5H11

H S

H

N H

C5H11

HO

H

H

H

S HO −H2O

−H2O

C5H11

C6H13

S

C5H11

O S

C5H11

C6H13

S

[O]

N

C5H11

C6H13 O

N H

HO

H2S

H2S

S

Figure 12 Formation of 2-pentylpyridine, 2-hexylthiophene, and 2pentyl-(2H)-thiapyran from 2,4-decadienal, ammonia, and hydrogen sulfide. Reproduced from Farmer, L.J., Mottram, D.S., 1990. Interaction of lipids in the Maillard reaction between cysteine and ribose: The effect of a triglyceride and three phospholipids on the volatile products. Journal of the Science of Food and Agriculture 53, 505–525.

O O Ammonia or amino acid H O

NH2

H N

H2N −2H2O

H O

N

RCHO

N

N R

N

R N

−H2O

N

OH R

N

Figure 13 Route to alkyldimethylpyrazines from the interaction of lipid-derived aldehydes with the Maillard reaction. Reproduced from Ho, C.T., Carlin, J.T., Huang, T.C., 1987. Flavour development in deep-fat fried foods. In: Martens, M., Dalen, G.A., Russwurm, H. (Eds.), Flavour Science and Technology. Chichester: Wiley, pp. 35–42.

Cooking of Meat | Maillard Reaction and Browning

O

O

OH

H3C

CH3

O

H3C

OH

H3C

O

H2O

H

401

CH3

CH3 O

O

H2O H3C

CH3

O

OH

O

N H3C

N

CHO H2O

H3C COOH

O

OH

CH3 H2O

O

CH3 O

OH

O

CH3

O

H O

HO

O H2O

CH3 HO

O

O

H3C

O

OH

H2O

CHO

CH3

O

COOH

O

O

H3C

OH

CH3 O

CH3

HO

CH3

O

Figure 14 Formation of colored condensation products from carbohydrate-derived carbonyls and 4-hydroxy-5-methyl-3(2H)-furanone (norfuraneol). Reproduced from Hofmann, T., Frank, O., Heuberger, S., 2001. The color activity concept: An emerging technique to characterize key chromophores formed by non-enzymic browning reactions. In: Ames, J.M., Hofmann, T. (Eds.), Chemistry and Physiology of Selected Food Colorants. ACS Symposium Series 775. Washington, DC: American Chemical Society, pp. 168–179, with permission from ACS.

H-OH CHO HC OH HC OH

+ RNH2 −H2O

R′

CH=NR HC OH

HC OH

HC NHR

HC OH

HC OH

HC OH

R′

R′

Condensation H

R N

H

H

H

R′ CHO

Glycolaldehyde Alkylimine Browning

R H

+

NH2R

Reverse-Aldol reaction

HC NHR HC OH

CH N R

N

H

H

R N+

H

H

N+

H H

.+ H2C NHR HC O

H

N R

N R

R

Figure 15 A possible pathway for formation of the free radical product and browning in the reaction of sugar with amino compound. Reproduced from Namiki, M., Hayashi, T., 1981. Formation of novel free radical products in an early stage of Maillard reaction. In Eriksson, C. (Ed.), Maillard Reactions in Food. Chemical, Physiological and Technological Aspects. Oxford, UK: International Union of Food Science & Technology, Pergamon Press, pp. 81–91.

of food by a cross-linking reaction between low-molecular weight MRP and high-molecular weight noncolored proteins. Lysine and arginine residues of protein help bind the carbohydrate-derived compounds to the protein backbone and produce the chromophoric substructures of melanoidins (Figure 16). Thus, proteins seem to act as noncolored skeletons of food melanoidins, to which different chromophoric substructures might be covalently bound through reactive side chains. Meat contains a fairly high protein content (e.g., 20– 25% in lean muscle tissue) and the carbohydrate-induced oligomerization and browning of proteins may be involved in the formation of melanoidins during thermal processing of meat. This leads, at least to some extent, to the characteristic dark brown color associated with roasted meat.

Summary The aroma of cooked meats is thermally derived, and the volatile compounds originate from both lipid- and watersoluble precursors. The Maillard reaction occurs during cooking of meat and is mainly responsible for the formation of a large number of heterocyclic compounds present in the volatile fraction of meat; these are responsible for the savory, roasted, and boiled flavors associated with cooked meat. Reducing sugars and amino acids of meat, notably ribose and cysteine, respectively, are important precursors for these reactions. Initial stages of the Maillard reaction lead to the formation of α-dicarbonyls such as 1-deoxyosones, 3-deoxyosones, and 1deoxyreductones through Amadori and Heyns intermediates.

402

Cooking of Meat | Maillard Reaction and Browning

R

OH

O CHO R N

R

R

O

H N N H

O

O

HO

R′

R′ N H

OH CH3

O

H N O

N

O

+ N

N

HN

O

O

R′

N H

R′

O

H N O

R′

N R O

O

H N

O

H N

N R

N H

R′ N H

O

R′

O

N

H2N

O

CH3

HO

H N N H

R'

O

O

H N N H

O

R′

R' N H

O

H N O

R′

Figure 16 Chromophoric substructures involved in melanoidin formation. Reproduced from Hofmann, T., 2001. Structure, colour and formation of low- and high-molecular weight products formed by food-related Maillard-type reactions. In: Ames, J.M., Hofmann, T. (Eds.), Chemistry and Physiology of Selected Food Colorants. ACS Symposium Series 775. Washington, DC: American Chemical Society, pp. 134–151, with permission from ACS.

The breakdown of these compounds yields key intermediates such as furfurals, furanones, and other dicarbonyl compounds. Other related reactions (e.g., the Strecker reaction) lead to the formation of simple compounds such as aldehydes, ammonia, and hydrogen sulfide, which are precursors for further reactions. Many different interactions of these compounds subsequently result in the formation of important classes of aroma compounds like furans, furanones, pyrazines, pyrroles, thiophenes, thiazoles (thiazolines), imidazoles, pyridines, oxazoles, cyclic ethylene sulfides, alkylsulfides, and disulfides. Of these compounds, aromatic nitrogen derivatives such as pyrazines, N-, S-heterocyclics like thiazoles, 2-methyl-3-thio (or sulfide)-furans, 2-methyl-5-thio (or sulfide)-thiophenes, sulfur-substituted tetrahydrofuranones, and nonaromatic ring sulfur derivatives with two or more sulfur groups are particularly important for the meaty-roasted flavor of cooked meats. Other constituents of the meat matrix, such as lipids, can react with products of the Maillard reaction. Lipid-derived aldehydes participate in Maillard reactions via reactions with hydrogen sulfide and ammonia to produce new volatile compounds. Lipid degradation products from phospholipids are particularly important and appear to control or limit the generation of sulfur compounds during thermal processing of meat. This process may be involved in the modification of flavor profiles of cooked meats and would depend on the type of meat (i.e., lean meat with less fat, meat with more unsaturated fatty acids) and reaction parameters (i.e., cooking method, temperature, duration of cooking) used. Owing to the complexity of the nonvolatile MRP, very little is known about the compounds responsible for the typical brown color on the exterior areas of products. According to the model experiments, both high- and low-molecular weight colored compounds generated during thermal processing contribute to the brown color on the surface of cooked meats.

See also: Cooking of Meat: Flavor Development; Physics and Chemistry; Warmed-Over Flavor

Further Reading Adams, A., deKimpe, N., 2006. Chemistry of 2-acetyl-1-pyroline, 6-acetyl-1,2,3,4tetrahydropyridine, 2-acetyl-2-thiazoline and 5-acetyl-2,3-dihyho−4 H−thiazine: Extraordinary flavour compounds. Chemical Reviews 106, 2299–2319. Antony, S.M., Han, I.Y., Rieck, J.R., Dawson, P.L., 2002. Antioxidative effect of Maillard reaction products added to turkey meat during heating by addition of honey. Journal of Food Science 67, 1720–1724. Bailey, M.E., 1983. The Maillard reaction and meat flavour. In: Waller, G.R., Feather, M.S. (Eds.), The Maillard Reaction in Foods and Nutrition. ACS Symposium Series, 215. Washington, DC: American Chemical Society, pp. 169–184. Bailey, M.E., 1998. Maillard reactions and meat flavour development. In: Shahidi, F. (Ed.), Flavour of Meat, Meat Products and Seafoods. London: Blackie Academic and Professional, pp. 267–289. Cadwallader, K.R., Shahidi, F., 2001. Identification of potent odorants in seal bubbler oil by direct thermal desorption-gas chromatography-olfactometry. In: Shahidi, F., Finley, J.W. (Eds.), Omega-3 Fatty Acids. Chemistry, Nutrition and Health Effects. ACS Symposium Series, 788. Washington, DC: American Chemical Society, pp. 221–235. Farmer, L.J., Mottram, D.S., 1990. Interaction of lipids in the Maillard reaction between cysteine and ribose: The effect of a triglyceride and three phospholipids on the volatile products. Journal of the Science of Food and Agriculture 53, 505–525. Farmer, L.J., Patterson, R.L.S., 1991. Compounds contributing to meat flavour. Food Chemistry 40, 201–205. Ho, C.-T., 1996. Thermal generation of Maillard aromas. In: Ikan, R. (Ed.), The Maillard Reaction. Consequences for the Chemical and Life Sciences. New York: John Wiley & Sons, pp. 27–53. Hodge, J.E., 1953. Chemistry of browning reactions in model systems. Journal of Agricultural and Food Chemistry 1, 928–943. Hofmann, T., 2001. Structure, colour and formation of low- and high-molecular weight products formed by food-related Maillard-type reactions. In: Ames, J.M., Hofmann, T. (Eds.), Chemistry and Physiology of Selected Food Colorants. ACS

Cooking of Meat | Maillard Reaction and Browning Symposium Series, 775. Washington, DC: American Chemical Society, pp. 134–151. Hofmann, T., Frank, T., Heuberger, S., 2001. The colour activity concept: An emerging technique to characterize key chromophores by non-enzymatic browning reactions. In: Ames, J.M., Hofmann, T. (Eds.), Chemistry and Physiology of Selected Food Colorants. ACS Symposium Series, 775. Washington, DC: American Chemical Society, pp. 168–179. Maillard, L.C., 1912. Action of amino acids on sugars. Formation of melanoidins in a methodical way. Compte Rendus 154, 66–68. Mottram, D.S., 1994. Flavor compounds formed during the Maillard reaction. In: Parliment, T.H., Morello, M.J., McGorrin, R.J. (Eds.), Thermally Generated Flavours. Maillard, Microwave and Extrusion Processes. ACS Symposium Series, 543. Washington, DC: American Chemical Society, pp. 104–126. Mottram, D.S., 1998. Flavour formation in meat and meat products: A review. Food Chemistry 62, 415–424. Mottram, D.S., Elmore, J.S., 2002. Novel sulphur compounds from lipid-Maillard interactions in cooked meat. In: Reineccius, G.A., Reineccius, T.A. (Eds.), Heteroatomic Aroma Compounds. ACS Symposium Series, 826. Washington, DC: American Chemical Society, pp. 93–101.

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Romero, M.V., Ho, C.T., 2007. Maillard reaction in flavour generation. In: Nolle, H. L.M.L. (Ed.), Handbook of Meat, Poultry and Seafood Quality. Oxford, UK: Blackwell Publishing, pp. 259–274. Schieberle, P., Hofmann, T., 2002. New results on the formation of important Maillard aroma compounds. In: Swift, K.A.D. (Ed.), Advances in Flavour and Fragrances: From the Sensation to the Synthesis. Cambridge, UK: Special publications of the Royal Society of Chemistry, pp. 163–177. Shahidi, F., 1998. Flavour of Meat, Meat Products and Seafoods, second ed. London, UK: Blackie Academic and Professional. Shahidi, F., Rubin, L.J., D’Souza, L.A., 1986. Meat flavour volatiles: A review of the composition, techniques, analyses and sensory evaluation. CRC Critical Reviews in Food Science and Nutrition 24, 141–243. Sun, W., Zhao, M., Cui, C., Zhao, Q., Yang, B., 2010. Effect of Maillard reaction products derived from the hydrolysates of mechanically deboned chicken residue on antioxidant, textural and sensory properties of Cantonese sausages. Meat Science 86, 276–282.

Physics and Chemistry K Palka and E W˛esierska, University of Agriculture, Kraków, Poland r 2014 Elsevier Ltd. All rights reserved. This article is a revision of the previous edition article by K Palka, volume 2, pp 567–570, © 2004, Elsevier Ltd.

Introduction Meat is a complex structure composed of muscle fibers, extracellular matrix, lipids, and water. The meat proteins are the main constituents that form the structure of the meat product. During heating they undergo significant structural changes and therefore the quality of the meat, mainly influenced by the meat structure, also changes significantly. Among the sarcoplasmic meat proteins there are globular proteins and enzymes. A typical example of globular proteins is myoglobin responsible for meat color. At increased temperatures the hydrophobic side chains of the compact globular proteins, in the aqueous environment, undergo expansion and partial unfolding, followed by association of unfolded proteins. The large degree of protein association decreases their solubility and precipitates are formed. If, however, the threedimensional network is formed, a gel sets. These gels bind the water and are solid-like in their mechanical behavior. The fibrous proteins (actin, myosin, titin, collagen) have a lot of hydrogen bonds and show electrostatic interactions that keep the molecules in register in the large building blocks, which in turn are broken during heating. The fibrous proteins contract on cooking in contrast to the globular proteins, which expand. Physicochemical processes that occur in the meat tissue during heating, causing significant changes in the spatial arrangement of the meat proteins, affect the final physicochemical and sensory properties of the heated meat. The method of heating is important too. For the same raw material, to achieve equivalent denaturation of proteins, more energy is needed during fast (40 °C min–1) than during slow (5 °C min–1) heating. Different heating rates dictate the rate of enzymatic and chemical reactions in the meat. They influence the conformation of the meat proteins, enzyme activity, solubility, and hydration and lead to thermal and hydrolytic rupture of peptide bonds, thermal degradation, and derivatization of amino acid residues, cross-linking, oxidation, and formation of sensory-active compounds. Most of those reactions can be reflected in the meat as either desirable or detrimental changes in color, flavor, juiciness, rheological properties, and enzyme activity, depending on the various combinations. These processes are affected by the temperature and time of heating, pH, oxidizing compounds, antioxidants, radicals, and other reactive constituents, especially reducing saccharides. The susceptibility of the meat proteins to thermal denaturation depends on their structure, predominantly on the number of cross-links, but also on the simultaneous action of other denaturing agents. Salt bridges, side chain hydrogen bonds, and a large proportion of residues in α-helical conformation increase the thermal stability of proteins. The stabilizing effect is related to heating temperature. On the one

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hand, thermal changes cause a decrease of solubility due to aggregation of the myofibrillar proteins, but on the other hand, they lead to an increase in solubility as a result of the degradation of tertiary protein structures of intramuscular collagen. Further effects of heating are gel formation (in most types of sausages and meat products), hydrolytic changes, alteration in the rate of proteolysis, and modification of the nutritive value.

Chemical Changes in Meat Protein Systems During heating of meat, conformational changes (heat denaturation) of the protein systems occur. These changes take place at a particular temperature, called the denaturation temperature. The next step in the structural changes during heating of meat are the protein–protein interactions resulting in loss of solubility and aggregation.

Sarcoplasmic Proteins (30% of Total Meat Proteins) Most of the sarcoplasmic proteins denature between 40 and 67 °C, but their heat aggregation may extend up to 90 °C. The aggregated sarcoplasmic proteins can form a gel between the structural meat elements in such a way that they have a role in the texture of the heated meat. This fraction of proteins also includes enzymes. Some of them have a tenderizing effect. During heating of the beef muscles at a temperature below 60 °C for a long time (heating rate of 0.1 °C min−1), the collagenases remain active in the meat, and tenderizing effect is achieved after 6 h, whereas they are inactived at faster heating at the end temperature of 70–80 °C.

Myofibrillar Proteins (65% of Total Meat Proteins) Heating of these proteins to a temperature of 65 °C causes a progressive increase of the surface hydrophobicity, whereas at higher temperatures it decreases again. This suggests that a part of the hydrophobic residues participates in protein–protein interactions leading to formation of aggregate network. According to differential scanning calorimetry measurements, α-actinin is the most labile and becomes insoluble at 50 °C; myosin and actomyosin denature between 54 and 58 °C; actin between 80 and 83 °C; tropomyosin and troponin at above 80 °C; and titin from pork and beef at 78.4 °C and 75.6 °C, respectively. The heat denaturation of myofibrillar proteins in solution usually results in a gel formation. It is caused by the fact that especially myosin forms gels at a very low concentration (0.5% w/w), compared to sarcoplasmic proteins (3% w/w). For purified myosin, the firmest gels are reached at 45 °C and pH

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Cooking of Meat | Physics and Chemistry 5.5 or at 60 °C and pH 6. Ionic strength and pH are important factors determining monomeric or filament structure of the myosin. At ionic strengths above 0.3 and at neutral pH, the myosin molecules are dispersed as monomers, forming a coarse network with large pores. At lower ionic strength the myosin molecules are assembled in filaments, and give a firmer gel. On heating, the gel formation of purified myosin occurs in two steps, in two separate temperature regions. The first part of the reaction (aggregation of the globular heads of myosin) occurs between 30 and 50 °C. The second stage (above 50 °C), connected with the structural changes in the helix structure of the myosin tails, leads to a network formation, where hydrophobic groups interact with each other. For the chicken-derived salt soluble myofibrillar proteins (SSP) heated in 0.6 M NaCl at pH 6, protein unfolding is observed at 30–32 °C, protein–protein association at 36–40 °C, and gelation at 45–50 °C. A lower degree of aggregation, better waterholding, and greater softness characterize the breast SSP gels, whereas a higher degree of aggregation and more hardness characterize the leg SSP gels.

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collagen decreases in the meat aged for 5 days remaining at the same level in the 12 day-aged meat. Therefore, differences in the thermal collagen solubility of the intramuscular connective tissue are a consequence of differences in the proportion of the collagen types, the level of heat-stable cross-linking, and the level of glucosaminoglycans in the structure, as well as the time of postmortem ageing and the method of heating. Heating also causes changes in pH, reducing activity, ionbinding properties, and enzyme activity. Slight upward change of pH (approximately 0.3 units) results from exposure of reactive groups of histidine. Increased reducing activity develops due to unfolding of the protein chains and exposition of sulphydryl groups. Conformational changes in proteins cause their ability to bind various ions, such as Mg2+ and Ca2+. Severe heating of the proteinaceous foods leads to a development of color and flavor compounds due to Maillard reactions and to thermal degradation of methionine and cysteine residues as well as other low-molecular weight compounds. The meat fat melts during heating. Solubilization of collageneous connective tissue provides channels through which melted fat may diffuse, as a component of thermal leak.

Connective Tissue Proteins (5% of Total Meat Proteins) The thermal denaturation of the meat collagen occurs in two steps. The first stage of the reaction is its shrinkage observed in the range of 53–65 °C. It involves the breakage of hydrogen bonds loosing up the fibrillar structure followed by the contraction of the collagen molecule up to one-quarter of its resting length. The second stage (gelatinization), running at approximately 70–80 °C, is connected with the breaking of heat-unstable intermolecular bonds. The degree of collagen shrinkage increases with the quantity of heat-stable (mature) links. In young animals the epimysium contains primarily heat-labile cross-links, the perimysium a mixture of heat-labile and heat-stable, and the endomysium of heat-stable crosslinks. With increasing animal age, the amount of the heatstable cross-links in the meat increases. Their higher levels lead to a development of greater tension in the connective tissue during heating. The shrinkage temperature of epimysial collagen is usually higher than that of other connective-tissue membranes in the muscle. The observations made by scanning electron microscopy (SEM) indicate that after heating of bovine sternomandibularis muscles at the temperature of 60 °C and 80 °C for 1 h, the epimysium does not show large changes, whereas the perimysial and endomysial collagen become granular at 60 °C and start to gelatinize at 80 °C. There are also differences in solubilization between different types of collagens. The highest thermal stability occurs in collagen of the endomysium, due to the large contribution of disulfide bonds in type IV collagen. The gelatinization of the intramuscular collagen depends also on the time of postmortem ageing of the meat, that probably results from changes in proteoglycans. In the 12-day-aged bovine semitendinosus (ST) muscles solubility of collagen is twice as high as in that aged for 5 days. During heating of the 5 day-aged bovine ST muscles by two methods in the range of temperatures between 50 and 100 °C, most of the soluble collagen is found at 70 °C during retorting and at 80 °C throughout roasting. During roasting of ST, when the temperature increases up to 90 °C, quantity of soluble

Water-Holding Capacity The raw meat contains 69–75% of water. Heating induces structural changes, which cause a decrease in water-holding capacity (WHC) of the meat. As the internal meat temperature increases, the WHC of meat decreases due to thermal denaturation of the meat proteins, especially myosin, which plays a significant role in water binding. During heating of meat, depending on the method, the amount of water decreases to 65% at internal temperature of 70 °C and to 60% at 90 °C. The water retention in the heated meat influences the quantity of the other basic constituents. The loss of water during heating of meat results from both evaporation and exudates. The fluid is drained by gravity from the cut surface of the meat, if the viscosity of the exudate is low enough and the capillary forces do not retain it. The loss of fluid arises predominantly from the longitudinal channels through the meat between the fiber bundles. In the raw muscle most of the water (80%) is held within the myofibrils. There are only changes in the water distribution, if the myofibrils change in volume. The fibers and fiber bundles shrink when their constituents (myofibrils) shrink, giving rise to the two extracellular fluid compartments around fibers and fiber bundles. The transverse shrinkage to the fiber axis, occuring mainly at 40–60 °C, widens the gap between the fibers and endomysium. At 60– 70 °C the connective tissue network and the muscle fibers cooperatively shrink longitudinally. This shrinkage causes the highest increase in water losses during heating. For the samples of heated meat, the amount of water around fiber bundles increases up to 50 °C, in comparison with the raw meat, which seems to be in accordance with the transverse shrinkage of fibers and fiber bundles. Above 50 °C, these widened gaps diminish up to 70 °C, probably mainly due to the shrinkage of the connective tissue. The increase in extracellular space from 70 to 90 °C may be connected with a swelling of the

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Figure 1 Connective tissue changes on heating. SEM micrographs of perimysium and endomysium from bull ST muscle: after ageing for 5 days at 4 °C and roasted to 70 °C (a) and to 90 °C (b); after ageing for 12 days at 4 °C and roasted to 70 °C (c) and to 90 °C (d). Reproduced from Palka, K., 2003. The influence of post-mortem ageing and roasting on the microstructure, texture and collagen solubility of bovine semitendinosus muscle. Meat Science 64, 191–198.

perimysium and solubilization of the intramuscular collagen, which occur at this range of temperature. The extent of the loss of the fluid depends on the WHC of the tissue and the degree of its marbling. The highly marbled meat shrinks less during heating and remains juicier than the lower marbled meat. The subcutaneous fat also reduces moisture losses during dry heating (roasting). The structural origin of water-holding in the whole meat and in the highly comminuted products is different. In the first, the crucial factor is the shrinkage or swelling of the myofibrils, and in the comminuted meat products, the ability of the meat proteins to form different types of gels. The comminution of meat with salt addition leads to solubilization of the meat proteins, which exists as a protein gel after heat treatment. The higher amounts of the soluble myofibrillar proteins create a dense protein network that holds more water.

Effects of Heating on Meat Microstructure When the meat proteins are exposed to heating, they first lose their tertiary structure and undergo several changes in configuration. In general, thermal denaturation leads to a loss in

protein solubility. These chemical changes are also associated with changes in the physical character of the meat tissues. Elastin, however, is not susceptible to effects of heat. The transverse shrinkage to the fiber axis occurs at 40–60 °C, which widens the gap already present at rigor between the fibers and their surrounding endomysium. There is a controversy regarding these observations. Some authors found no changes in the cross-sectional area on cooking of the neck muscle, whereas others found that the transverse shrinkage of both fibers and fiber bundles of bovine psoas major muscle starts at approximately 40 °C. There is also a disagreement between the results presented in the literature with regard to the temperature, in which the longitudinal shrinkage of the fiber starts. Some observations indicate that fibers do not shorten below 60 °C, and the others, that both sarcomere shortening and fiber shortening usually begin at temperatures of 40–50 °C. The divergence in the results may be due to the large biological diversity within a muscle as well as between different muscles. At 60–70 °C the connective tissue network and the muscle fibers shrink. This is mainly based on the fact that the perimysial collagen shrinks at approximately 64 °C. In the bovine ST muscles aged for 5 or 12 days and roasted to internal temperatures in the range of 50–90 °C and then

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Figure 2 Myofibrillar changes on heating. SEM micrographs of myofibrils from bull ST muscle: after ageing for 5 days at 4 °C and roasted to 70 °C (a) and to 90 °C (b); after ageing for 12 days at 4 °C and roasted to 70 °C (c) and to 90 °C (d). Reproduced from Palka, K., 2003. The influence of post-mortem ageing and roasting on the microstructure, texture and collagen solubility of bovine semitendinosus muscle. Meat Science 64, 191–198.

visualized using SEM, no significant structural changes are seen at the internal temperature of 50 °C. However, in the range between 60 and 90 °C, significant changes occur both in the myofibrils and in the intramuscular connective tissue, and this is further affected by the degree of postmortem ageing. The changes in the connective-tissue structure of perimysium and endomysium during roasting of the 5-day-aged bull ST muscles to 70 °C are shown in Figure 1(a) and to 90 °C in Figure 1 (b), for the 12 day-aged muscle, the changes are shown in Figure 1(c) and (d), respectively. The granulation of perimysium and the cracks of endomysium tubes are observed in 5 day-aged meat roasted to an internal temperature of 80–90 °C (Figure 1(b)), however, in 12 day-aged meat after roasting to 60–70 °C (Figure 1(c)). The changes in the myofibrillar structure during roasting of the 5-day-aged bull ST muscles to 70 °C are shown in Figure 2(a) and to 90 °C in Figure 2(b), whereas for the 12 day-aged muscle in Figure 2(c) and (d). In the 5 day-aged samples the disintegration of the myofibrillar structure starts at 70 °C (Figure 2(a)) and is considerable at 90 °C (Figure 2(b)). In the 12 day-aged meat roasted to 70 °C (Figure 2(c)), the degree of structural destruction is similar to that of 5 day-aged meat roasted to 90 °C (Figure 2(b)). At 90 °C complete disintegration of the myofibrillar structure of 12 day-aged meat is observed (Figure 2(d)).

As the endpoint temperature increases from 50 to 60 °C, there is a significant decrease in the fiber diameter. As the heating temperature is raised, the sarcomere length decreases, the effects being greater in the aged meat. The larger structural changes observed during roasting of the more aged meat may be a consequence of the changes during ageing in both the cytoskeletal proteins and the intramuscular connective tissue, leading to a weakening of the transversal and longitudinal integrity of the muscle fibers. In general, the microstructural changes are considerably less in the meat heated after 5-day ageing in comparison with the meat heated after 12-day ageing. There is a high negative correlation (r¼ −0.97) between changes in the sarcomere length and the cooking losses during heating of the bovine ST at the temperature range of 50–120 °C (Figure 3).

Texture and Tenderness of Heated Meat The rheological properties of meat result from changes in proteins, with the texture of the meat being affected mainly by the quantity and cross-linking of collagen; the morphological structure of the meat tissues; the biochemical state of the

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Figure 3 Effect of heating temperature on cooking losses (–) and sarcomere length (– – –) of beef ST muscle samples retorted after 5 days ageing at 4 °C. Reproduced from Palka, K., Daun, H., 1999. Changes in texture, cooking losses, and myofibrillar structure of bovine M. semitendinosus during heating. Meat Science 51, 237–243.

muscle pre- and postrigor; and the mechanical disintegration of the muscle structure. The hardening of the myofibrillar structure and the gelatinization of the intramuscular collagen depend on the extent of the postmortem changes (ageing) related to the timetemperature regime. Generally, hardening of meat is observed throughout the heating. The first increase of meat hardness that occurs after heating in the range of 40–65 °C is mainly due to sarcoplasmic and actomyosin complex protein denaturation. A contribution of intramuscular connective tissue to the changes of toughness is relatively small, although heatinduced shrinkage of endomysium occurs. This is because the endomysium is an amorphous, nonfibrous sheet. However, some authors observed an increase in tenderness of the meat heated up to approximately 50 °C. The reason for this is probably the fact that the applied stress during mastication is reduced by viscous flow in the fluid-filled channels in between fibers and fiber bundles. The viscous flow then becomes lower as the elasticity of the meat increases in that temperature region. At above 65 °C elasticity acts adversely and impairs the tenderness, Warner–Brazler (WB) shear force increases significantly. The further hardening that occurs at 65–75 °C is connected with the drastic shrinking of the perimysium and continuation of the myofibrillar component shrinking. In the range of 75–80 °C, there is further shrinkage and dehydration of the actomyosin component. The collagen fibers begin to granulate, which can result in crispness of the perimysium. At this time the combining effects of the myofibrillar component and the perimysium are observed, and the increase in WB shear force becomes lower, compared with the second phase. At higher temperatures (80–90 °C), the overall influence of thermal-induced changes in the intramuscular connective tissue is a tenderizing effect,

whereas the changes in myofibrillar proteins result in a toughening effect. Meat hardness depends on the fiber size and the degree of sarcomere shortening during heating to 70 °C through tension caused by collagen fibers (mainly endomysium) shortening. This is also influenced by many of the differences in the histological structure and the amount of the collagen fibers type III and type I as well as differences in the collagen crosslinking. For example, mechanical resistance of the perimysium at the interface with the endomysium mostly affects hardness of the heated meat, whereas endomysium shrinkage may result in a tightening of the structure and squeezing out of intramuscular water. Prolonged heating of meat (4–6 h) at relatively low temperatures (50–60 °C) improves tenderness because of enzyme activity up until 60 °C. Drip loss ranging from 20% to 40% of the original weight and shrinkage also has an effect on rheological properties. Meat with a high pH has lower cooking losses and is more tender after heating. For the bovine ST and psoas major muscles at the same stage of ageing, boiled (100 °C), roasted (170 °C), or fried (160 °C) to the end temperature of 75 °C, WB shear force values are the highest for boiled, middle for roasted, and the lowest for fried muscles indicating that the method of heating is also important. The sensory-evaluated toughness of the whole bovine biceps femoris muscle decreases drastically in the range of temperature from 55 to 60 °C, thereafter increases again up to 80 °C. For the comminuted meat products from the same muscle, the hardness increases over the whole temperature range and is significantly lower than the toughness of the whole meat at heating temperatures below 60 °C. It means that the spatial arrangement of the fibers is most important for the textural properties of the meat and the comminuted meat products.

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See also: Chemical and Physical Characteristics of Meat: Chemical Composition; Palatability. Connective Tissue: Structure, Function, and Influence on Meat Quality. Conversion of Muscle to Meat: Glycolysis. Cooking of Meat: Cooking of Meat; Flavor Development; Heat Processing Methods; Maillard Reaction and Browning; Warmed-Over Flavor

Further Reading Bailey, A.J., Light, N.D., 1989. Connective Tissue in Meat and Meat Products. London: Elsevier. Kołczak, T., Krzysztoforski, K., Palka, K., 2008. Effect of post-mortem ageing, method of heating and reheating on collagen solubility, shear force and texture parameters of bovine muscles. Polish Journal of Food and Nutrition Sciences 58 (1), 27–32. Kołczak, T., Pospiech, E., Palka, K., Ł˛acki, J., 2003. Changes of myofibrillar and centrifugal drip proteins and shear force of psoas major and minor and semitendinosus muscles from calves, heifers and cows during post-mortem ageing. Meat Science 64, 69–75. Laakkonen, E., 1973. Factors affecting tenderness during heating of meat. Advances in Food Research 20, 257–323. Lawrie, R.A., 1998. Meat Science. Oxford: Pergamon Press.

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Li, C.B., Zhou, G.H., Xu, X.L., 2010. Dynamical changes of beef intramuscular connective tissue and muscle fiber during heating and their effects on beef shear force. Food Bioprocess Technology 3, 521–527. Nishimura, T., Hattori, A., Takahashi, K., 1996. Arrangement and identification of proteoglycans in basement membrane and intramuscular connective tissue of bovine semitendinosus muscle. Acta Anatomica 155, 257–265. Offer, G., Knight, P., 1988. The structural basis of water-holding in meat. In: Lawrie, R. (Ed.) Developments in Meat Science, vol. 4. London: Elsevier, pp. 63–243. Offer, G., Knight, P., Jeacocke, R., et al., 1989. The structural basis of the waterholding, appearance and toughness of meat and meat products. Food Microstructure 8, 151–170. Palka, K., Daun, H., 1999. Changes in texture, cooking losses, and myofibrillar structure of bovine M. semitendinosus during heating. Meat Science 51, 237–243. Palka, K., 2003. The influence of post-mortem ageing and roasting on the microstructure, texture and collagen solubility of bovine semitendinosus muscle. Meat Science 64, 191–198. Pospiech, E., Greaser, M.L., Mikołajczak, B., Chiang, W., Krzywdzinska, M., 2002. Thermal properties of titin from porcine and bovine muscles. Meat Science 62 (2), 187–192. Purslow, P.P., 2002. The structure and functional significance of variations in the connective tissue within muscle. Comparative Biochemistry and Physiology Part A 133, 947–966. Sikorski, Z.E., 2007. Proteins. In: Sikorski, Z.E. (Ed.), Chemical and Functional Properties of Food Components. New York: CRC Press, pp. 155–160. Tornberg, E., 2005. Effects of heat on meat proteins – Implications on structure and quality of meat products. Meat Science 70, 493–508.

Warmed-Over Flavor RB Pegg and AL Kerrihard, University of Georgia, Athens, GA, USA F Shahidi, Memorial University of Newfoundland, St. John’s, NL, Canada r 2014 Elsevier Ltd. All rights reserved.

Glossary Chelators Organic chemicals that form two or more coordination bonds with a central metal ion. Heterocyclic rings are formed with the central metal atom as part of the ring. Gas chromatography–mass spectrometry An analytical method that combines the features of gas–liquid chromatography and mass spectrometry to identify different substances within a test sample. Heme compound An iron compound of protoporphyrin, which constitutes the pigment portion or protein-free part of the hemoglobin molecule and is responsible for its oxygen-carrying properties. Maillard reaction products Any of hundreds of different compounds created as a result of the Maillard reaction

Introduction It has been more than 50 years since the term ‘warmed-over flavor’ (WOF) was first coined in reference to a notable deterioration in the quality of cooked meat products following chilled storage followed by reheating. Even though still most frequently linked to chill-stored cooked meat, the term today is somewhat of a misnomer, as it may apply to deterioration of meat flavor in a variety of different contexts, including raw meat, meat served on warmers, and meat in frozen storage. The onset of the distinctive off-flavor was originally attributed solely to lipid oxidation, but it is now understood that protein oxidation is of importance as well. Meats that are cooked before storage are most susceptible to the development of noticeable off-flavors, because heat treatment accelerates the oxidative processes (the distinctive off-flavor can become readily apparent within just a few hours of thermal processing). Products develop an undesirable stale flavor, and at the same time desirable meaty flavor notes are lost. The stale off-flavors so formed have often been described as ‘cardboard like,’ ‘painty,’ and ‘rancid’; they are considered most noticeable when refrigerated cooked meat products are reheated. The demand for precooked, readyto-eat meat products in the marketplace and in fast-food franchises continues to grow, thereby expanding the concern of consumer exposure to WOF. However, a greater awareness of the process, along with improved methods of control, ensures the loss in quality of meat products due to the development of WOF, which occurs to a much lesser extent today than it did 50 years ago. When the concern of WOF is raised, it is often in relation to comminuted products, such as meat loaves, chicken nuggets, and precooked burgers. Thus, it is generally accepted that any process involving disruption of the integrity of muscle tissue (such as cooking, grinding, mechanical deboning, massaging, or restructuring) enhances the development of WOF. Warmed-over

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(a process of nonenzymatic browning resulting from a chemical reaction between an amino acid and a reducing sugar). Many of the products are of interest for their flavor attributes, and also for their possible antioxidative properties. Pyrolysis The thermochemical decomposition of organic material. Singlet oxygen The electronically excited state of molecular oxygen, which is less stable than the more typical ground-state triplet oxygen. Umami A strong meaty taste imparted by glutamate and certain other amino acids. It is often considered to be one of the basic taste sensations along with sweet, sour, bitter, and salty.

flavor is also a big concern for the hotel/restaurant/institution service where processed convenience entrées or prepackaged cooked meat products are served. Prolonged holding of products containing meat at high temperatures (such as in a steam table) can produce undesirable flavors. Freezing can delay the onset of WOF development, but it does not prevent it. Stale or off-flavor notes, such as ‘ice box,’ ‘rancid,’ and ‘freezer burn,’ have been used to describe the phenomenon. The flavor compounds responsible for the off-flavor in stored fresh meat are qualitatively the same as in previously cooked meat, but the compounds occur at different concentrations and therefore create a somewhat different aroma profile. Because WOF development is a dynamic process of flavor change due principally to a cascade of oxidative events, an understanding of the mechanism(s) and prevention of its occurrence in meat and meat products are important to the food scientist.

Warmed-Over Flavor as a Consequence of Lipid Oxidation WOF development is attributable mainly to lipid oxidation. Meat lipids are made up of intermuscular and intramuscular adipose tissues, and they contain both saturated and unsaturated fatty acids. The membrane lipids (i.e., the phospholipids) tend to possess the lion’s share of the polyunsaturated fatty acids (PUFAs), and these are most prone to oxidation. Membranes are disrupted when meat is ground, chopped, or cooked, thereby releasing cell contents and exposing PUFAs to oxidative stress. Consequently, the process of WOF development can begin within hours of cooking the meat product, as compared with several days for the development of lipid oxidation in uncooked meat. Research has shown that subcutaneous fat from meat can produce approximately 50 volatile compounds during WOF development,

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Cooking of Meat | Warmed-Over Flavor whereas intramuscular lipids can generate more than 200. There seems to be no question that oxidation of phospholipids is the primary source of off-flavor notes generated during WOF development. Oxidation of the unsaturated C18 fatty acids found in meat (namely oleic, linoleic, and α-linolenic acids) produces low molecular weight aldehydes (C3–C12), which are believed to be partly responsible for the development of WOF and rancidity in cooked meats during storage. Hence, it can be reasonably hypothesized that meats containing higher levels of PUFAs should be more susceptible to oxidation. This is indeed the case as certain muscle tissue exhibits more of a propensity toward the development of WOF, with a key correlating factor being the degree of unsaturation in the tissue’s fatty acids. Fish is most at risk followed by poultry, pork, beef, and lamb. The initial stage in the oxidation of unsaturated fatty acids involves the formation of lipid free radicals – potent species that react with oxygen and propagate the process via a chain reaction. This phenomenon, commonly referred to as autoxidation, can be triggered by singlet oxygen, metal ions, heme compounds, UV light, and certain enzymes. Thermal processing results in changes to protein and lipid constituents of meat and destroys some of the natural reducing capabilities found in muscle tissue, which help to combat oxygen stress and free radical generation. During autoxidation, primary products of lipid oxidation (known as hydroperoxides) are formed. Lipid hydroperoxides are odorless and tasteless but quite unstable. Their degradation leads to the formation of a large number of secondary oxidation products, such as aldehydes, acids, alkanes, alkenes, ketones, alcohols, esters, epoxy compounds, and polymers. Aldehydic scission products of hydroperoxides, such as pentanal, hexanal, and E,E-2,4-decadienal, are of key interest, as these short-chain aldehydes give rise to the offflavors known as ‘warmed-over’ and are very potent volatiles even at concentrations in the parts-per-billion range. When refrigerated cooked meats are warmed up/reheated, these active off-flavor compounds volatilize and the unpleasant WOF notes become more noticeable. Hexanal, which is the main oxidation breakdown product of linoleic acid, is sometimes monitored as an indicator of meat lipid oxidation. Conflicting views exist concerning the role of heme and nonheme iron as it relates to lipid oxidation during cooking of meats and the subsequent formation of WOF in stored products. Some researchers have reported that heat treatment of meats releases ferrous iron from heme-containing compounds (such as myoglobin), which then acts as a primary catalyst in oxidative processes resulting in WOF. However, several investigations have suggested that the intact heme iron is in fact a stronger prooxidant in muscle tissue than iron that has been released. Data from heme-containing model system studies suggest that changes in protein structure occur during heating, which expose the heme cavity to the surrounding lipid hydroperoxides and thereby increase the prooxidative activity of the catalytic heme group. In other words, it is asserted that it is the heme compounds themselves and not free iron(II) or iron(III) which have considerable prooxidative activity at the concentrations relevant to meat. Addition of sodium chloride is mandatory in meat formulation for flavor and functionality, but the chloride ions promote iron-catalyzed oxidation of unsaturated lipid

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constituents and therefore its use facilitates oxidation. Other trace metal ions, such as copper, that can be introduced to meat via water and processing equipment are also promoters of oxidation. These trace metal ions can react directly with lipids in oxidation reactions by reducing the energy of activation necessary for free radical formation or serving to catalyze the decomposition of formed lipid hydroperoxides.

Warmed-Over Flavor as a Consequence of Protein Oxidation It was initially believed that lipid oxidation was the sole cause of WOF development, but in the late 1980s several researchers produced strong evidence that protein degradation reactions were also involved in WOF development. Flavor chemists have been quite interested in the chemical instability of sulfurcontaining constituents in meat (i.e., sulfhydryl–disulfide interchanges in proteins and the degradation of sulfur-containing heteroatomic compounds) because breakdown of these compounds is believed to lead to a reduction in desirable meaty flavor notes. In an effort to better describe the complex series of chemical reactions that contribute to an overall increase in off-flavor notes and a loss in desirable meaty ones, the term ‘meat flavor deterioration’ (MFD) was proposed as an alternative to WOF. Although MFD may be a better expression for what is actually occurring, the term ‘warmed-over flavor’ and the WOF acronym are still routinely used in the scientific literature. Although the intensity of the undesirable sensory notes has been positively correlated with the content of carbonyl compounds formed via lipid oxidation reactions, the decrease in flavor intensity of desirable notes can be attributable to both lipid oxidation and protein oxidation. Protein oxidation might decrease the concentration of those volatiles that contribute to desirable meaty flavor, whereas the off-flavors produced by lipid oxidation might ‘mask’ the perception of such desirable compounds. The reduction or disappearance in the sensory perception of ‘meatiness’ due to changes to heteroatomic compounds is probably important during the early days of storage when lipid oxidation-derived odors and flavors are not as concentrated, and flavor masking probably becomes the main factor during the later days of storage when WOF is more fully developed. Another contributing factor to the dull flavor impact associated with WOF could be the loss of peptides to enzymatic degradation. Research has revealed that some meat enzymes remain active even after thermal processing and subsequent refrigeration of the product, including those that might break down peptides that are capable of stimulating the taste receptors to give a note of ‘umami’ (a Japanese term for a fifth basic taste that is triggered by some amino acids, translating roughly to ‘savory’ or ‘meaty’).

Sensory and Chemical Analysis in Relation to Warmed-Over Flavor The contribution of sensory analysis toward the development of descriptors, definitions, and references to describe the

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Table 1

Cooking of Meat | Warmed-Over Flavor Sensory descriptive terms with definitions developed for the evaluation of warmed-over flavor in ground chicken

Term

Definition

Reference

Ratinga

Odors Chicken brothy Fishy Sulfury Musty Rancid

Aromatics associated with Chicken broth Cooked fish Boiled egg yolk Wet cardboard Oxidized oil

Chicken broth Freshly cooked tilapia Boiled egg yolk Wet cardboard Oxidized flax seed oil

12 10 5 4 Noneb

Tastes Sweet Sour Salty Bitter Umami

Taste associated with Sucrose Citric acid Sodium chloride Caffeine Monosodium glutamate

5% sucrose 0.08% citric acid 0.5% sodium chloride 0.05% caffeine 0.1% monosodium glutamate

5 5 5 5 7.5

Flavors Metallic/serumy Cooked chicken Fatty Fishy Rancid

Flavor associated with Blood or rare meat Cooked chicken breast Rendered chicken fat Cooked white fish Rancid/oxidized oil

Rare beef (top sirloin) Boiled chicken breast Rendered chicken skin Freshly cooked tilapia Oxidized flax seed oil

3 9 8 11 6

Appearance Surface color

Color of the outer surface of the sample

Boiled chicken breast Rare beef (top sirloin)

1 14

a

Ratings assigned according to a 15-point scale; a larger number signifies a greater degree of intensity for the associated trait within the reference sample. A rating was not determined for the reference sample of the ‘rancid’ odor term. Source: Reproduced from Brannan, R.G., 2009. Effect of grape seed extract on descriptive sensory analysis of ground chicken during refrigerated storage. Meat Science 81, 589−595. b

phenomenon of WOF in cooked meat products has come a long way in the last 50 years. Today, well defined sensory descriptive vocabularies for WOF have been prepared that allow trained panelists to accurately track the development of WOF with time. An example lexicon of flavor descriptors used for ground chicken is presented in Table 1. Such a vocabulary can be used by panelists to describe perceived sensory characteristics in a sample set – producing a perceptual map of the variations in a sample type. Sensory analysis can be employed alone or in combination with chemical/instrumental data to help explain and elucidate underlying sensory and chemical relationships. Data from the mid-1980s indicate that the sensory perception of WOF was similar across meat patties of beef, pork, chicken, and turkey, but the intensity of its occurrence varied among the samples. Some specific data on beef showed that the intensity of fresh cooked beef notes is strong immediately after cooking, but over time, cardboard notes develop and then disappear. At about the same time, there is a marked reduction in fresh beefy notes, and then oxidized notes begin to become apparent. For samples that had been stored for 3–7 days, oxidized/rancid/ painty notes were dominant. There are a variety of chemical methods to semiquantify WOF development in meat and meat products, including the measurement of changes in conjugated dienes and carbonyl values as well as the more recent employment of electronic noses and gas chromatography. Malon(di)aldehyde is a relatively minor product of autoxidation of PUFAs in muscle tissue, but its presence and concentration in meat products is commonly monitored as a marker of lipid oxidation by the classical 2-thiobarbituric acid (TBA) test. The TBA test involves the reaction of malonaldehyde in oxidized foods with the TBA

reagent under acidic conditions; a pink adduct forms with a distinctive absorption maximum at 532 nm. The TBA test was once believed to be specific for malonaldehyde, but this is not so. In fact, the TBA method has been criticized for lacking specificity and adequate sensitivity toward the dialdehyde. Owing to the uncertainty about the exact identity of compounds that can react with the TBA reagent, the ambiguous term ‘2-thiobarbituric acid-reactive substances’ (TBARS) is now commonly employed in lieu of TBA number or value. Nevertheless, determining the content of TBARS (i.e., often reported as mg malonaldehyde equivalents per kg meat) appears to be a useful indicator of meat quality deterioration. Recent studies have shown that TBARS are highly correlated with many of the sensory terms related to WOF. However, the importance of hexanal, a dominant volatile oxidation product of linoleic acid, as an indicator of the sensory perception of WOF development has been questioned. Hexanal has a characteristic ‘tallowy’ or ‘green leafy’ aroma, but this odor term was not strongly perceived as being associated with WOF odor terms (e.g., linseed oil like and cardboard like) during vocabulary development. Results from gas chromatography–mass spectrometry analyses have indicated that oxidation compounds, such as pentanal, 2-pentylfuran, octanal, nonanal, 1-octen-3ol, and hexanal, covaried with the sensory descriptor green.

Preventive Strategies It can be important to food scientists to understand how to control or limit WOF development in meat and meat products and to know what arsenal of countermeasures are available.

Cooking of Meat | Warmed-Over Flavor By examining the causes of off-flavor development, strategies can be designed to limit its occurrence. Curtailing the detrimental effect of WOF requires the inhibition of lipid oxidation, protein oxidation, the consumer’s ability to detect the resulting reduction in sensory quality, or some combination thereof. Although much of the methods to diminish WOF have historically focused on the inhibition of lipid oxidation, it is important to note that these procedures have largely been considered effective measures against protein oxidation as well. The most recent evidence now shows that protein oxidation can, in fact, be inhibited very effectively by strategies that include the incorporation of primary antioxidants. Many find the most effective means of controlling WOF to be a comprehensive strategy that utilizes a combination of the approaches described below.

Meat Quality and Handling The choice of meat is an important factor in the occurrence of lipid oxidation. Fish and other muscle tissues containing high levels of PUFAs exhibit more of a propensity toward off-flavor development. Chicken has less of a tendency to develop oxidized flavors than turkey due to the higher level of the antioxidant vitamin E in chicken; nevertheless, the problem will be worse in chicken thigh meat than in white meat, as the darker meat contains more lipids and heme iron. Fresh meat used in product formulations shows less of a tendency to develop WOF than older meat, as older meat will have more time to undergo enzymatic degradation processes, which generate autocatalytic compounds that can propagate oxidation. Endogenous antioxidant enzymes, such as catalase, glutathione peroxidase, and superoxide dismutase, continue to function postmortem at curbing lipid oxidation in uncooked muscle foods. However, their efficacy in this regard diminishes with increasing age of the meat. Ensuring that high quality meat is used in product formulations is critical. In addition to quality meat selection, some steps can be taken at the operator level to limit WOF. Incorporating antioxidants into the product and reducing the time from cooking to plate are among the most effective and common means food service operators can utilize to minimize WOF. WOF can also be curbed by avoiding the use of steam tables and warming lights to hold products at elevated temperatures for long periods of time. Many fast-food franchises make an effort to ensure that their burger products stay under warming lights for relatively short periods so they do not lose that fresh-grilled flavor. The actual cooking method employed for precooked products can also influence the extent of WOF. One might assume that grilling of meat would exaggerate the potential for WOF on account of the high temperatures to which lipid and protein constituents are subjected, but this is not so. In fact, thermal processes that employ very high temperatures, like grilling, seem to inhibit WOF development through the formation of antioxidant Maillard browning intermediates. Details of how this occurs have been discussed in a previous article. Similarly, conditions that favor browning, such as addition of glucose or smoke intermediates, can help to retard or inhibit WOF development.

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Primary Antioxidants: Synthetic and Natural Food technologists attempt to reduce the problem of WOF in meat products by adding food-grade antioxidants or ingredients that impart antioxidant properties. Primary antioxidants extend the induction period and delay the onset of fatty acid oxidation by acting as free radical acceptors or hydrogen atom donors. Such antioxidants trap free radicals directly and delay the free radical chain reaction in a concentration-dependent manner. Synthetic compounds such as tert-butylhydroquinone, butylated hydroxyanisole, butylated hydroxytoluene, and propyl gallate are commonly employed antioxidants by the food industry. Their usage levels, however, are strictly regulated, and in recent years consumers have demonstrated reluctance to consume such compounds. Fortunately, there are a wide variety of natural alternatives that can also offer protection against oxidation in the form of food ingredients. The most common natural antioxidants utilized to fight WOF are vitamin E, extracts from rosemary and sage, and carotenoids such as β-carotene and lycopene. In addition, many other spices, fruits, and vegetables contain constituents with antioxidant properties that can provide benefits to a meat formulation. Reducing exposure of these antioxidants to oxygen and light enhances their effectiveness in minimizing WOF development. The addition of spice and herb extracts to meat products has become a popular means of incorporating natural antioxidants and represents a ‘consumer-friendly’ option. Rosemary, oregano, and sage extracts have been of common use in recent years, oftentimes in combination with tocopherols and/ or erythorbate. Rosemary in particular appears to be the most effective, as it contains a number of antioxidant compounds called diterpenes (including the highly active and prevalent carnosic acid). Because carnosic acid and rosmanol (another antioxidant constituent of rosemary) are odorless, manufacturers can develop spice-based ingredients with reduced flavor impact and increased protection against oxidation and the subsequent WOF development. Spice companies continue to develop new odorless extracts possessing antioxidant activity for addition to meat systems. Yeast extracts and its derived products also exhibit antioxidant properties due to the presence of glutathione, Maillard reaction products, and sulfur-containing amino acids. Papers that cite the benefits of new food ingredients against WOF appear frequently in the scientific literature, many of which describe the employment of novel plant extracts.

Dietary Antioxidants Typically, antioxidants are added to meat products during formulation, but scientists have demonstrated the potential to increase the antioxidant capacity of muscle tissue before the animal being harvested. One such approach is to supplement the feed of domesticated species with dietary antioxidants. A number of studies with hogs and poultry have shown that supplementation of feed with vitamin E (typically as α-tocopheryl acetate) can minimize the potential for eventual WOF development. Additions to supplementation levels have been found to result in progressive increases in the

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Cooking of Meat | Warmed-Over Flavor

concentration of α-tocopherol in the resulting muscle tissue, mitochondria, and microsomes. α-Tocopherol migrates into muscle cell membranes, where it lies adjacent to highly oxidizable phospholipids; this localization makes α-tocopherol a particularly effective antioxidant. Sensory studies of meat products have shown that vitamin E supplementation can prolong flavor freshness, inhibit WOF development, and positively influence tenderness and juiciness.

Secondary Antioxidants Secondary antioxidants inhibit oxidation by indirect means, such as scavenging oxygen or binding prooxidative compounds, and provide another method of reducing oxidation in meat products – most commonly via the incorporation of chelators. A chelator or sequestrant is a food additive that reacts with trace metal ions in foods and forms tightly bound complexes, thereby inhibiting the metal ion’s catalytic action on lipid constituents. Typical chelators added to processed meat products are alkaline phosphates. Not only do alkaline phosphates improve the functionality of the meat product in question (via water-binding capacity, chewiness, and other textural attributes), but also they have the ability to complex with or ‘chelate’ free iron ions in the meat matrix. Furthermore, sodium tripolyphosphate, tetrasodium pyrophosphate, and sodium hexametaphosphate have the capability to complex with iron ions that are released from the heme moiety of myoglobin during thermal processing. The level of added phosphates must be controlled because additions of 0.5% or more tend to leave metallic and bitter tastes in the product. Citric, ascorbic, and ethylenediaminetetraacetic acids are additional common food-grade additives that help to stabilize metal ions by reducing their capability to act as oxidants. Ascorbic acid, its sodium salt (sodium ascorbate), and its isomer (erythorbate) also function synergistically with other antioxidants and added polyphosphates to give protection to meats against oxidative degradation.

Nitrites and Nitrates Nitrites and nitrates are additives to meat products that perform multiple functional roles in the meat matrix, one of them being to retard oxidation and WOF development. The mechanism by which nitrites prevent oxidation within meat (and subsequently WOF development) is still a matter of discussion. Four different mechanisms have been proposed for the antioxidative effect of nitrite in meats: (1) formation of a stable complex between heme pigments and nitrite, thereby preventing the release of iron ions from the porphyrin molecule; (2) stabilization of unsaturated lipids within tissue membranes against oxidation; (3) chelation of metal ions; and (4) formation of antioxidative nitroso and nitrosyl compounds.

Natural and Liquid Smoke Smoking is another popular meat preservation technique. Like nitrites, constituents of smoke (specifically, phenolic compounds) impart antioxidant properties to meat and meat

products. Additionally, incomplete combustion of gases during natural smoke generation from the pyrolysis of hardwood can result in the formation of various nitrogen oxides, which can function in the curing process as nitrite does. Research has shown that certain smoke flavorings can reduce the occurrence of WOF and extend shelf life when added to fresh, precooked, and processed meats. Formulators can add liquid smoke to their products directly by atomizing, dipping, drenching, spraying, or injecting. Smoke ingredients with strong flavors can help to mask the perception of WOF, whereas flavorless smoke fractions can be employed at low levels in marination systems to reduce the development of WOF. In some cases, the incorporation of smoke flavors has reduced lipid oxidation by 20–30%. The flavors also contain certain carbonyls that react with amino groups of meat proteins to inhibit WOF production.

Packaging Packaging is a physical means to reduce off-flavor development in meat and meat products. Because light and the presence of oxygen can accelerate oxidation, eliminating their exposure through packaging technologies will help. Vacuum packaging controls oxygen interactions at the meat surface, and thereby minimizes oxidation. This technique, coupled with nitrogen flushing or modified atmosphere packaging (e.g., 70% N2 and 30% CO2) techniques, can give substantial shelf life to finished products. Other packaging technologies, such as oxygen scavengers, can be added to the package as stand-alone units or be incorporated into the packaging film. Another approach employed by the packaging industry is the use of films that act as oxygen barriers. Edible films containing natural antioxidants have been examined as a means to control WOF development in cooked meat products, but the release and delivery of the actives require further elucidation. WOF development was recently inhibited by whey-based edible coatings of sausages, with the speculated mechanism being chelation by present carboxymethyl cellulose. In some cases, it is more effective to mix the antioxidant directly into the meat formulation, but this does not work for wholemuscle and some restructured meat products.

Flavor Masking Flavor masking or other methods using flavors that modify the perception of off-notes can be effective tools in the fight against oxidative off-flavors in meat products. An example to which has already been eluded is that of smoking. Addition of complementary (i.e., savory) flavors from herbs and spices can not only inhibit lipid oxidation but also potentiate meat flavors, which might otherwise fade during processing and refrigerated storage. Beer flavoring is another ingredient that helps to reduce the flavor problems that occur during the reheating of meats. Beer flavoring’s anti-WOF effect might be a function of the typical yeast notes found in the brew, as yeastbased flavors can improve and enhance flavors, mask bitterness, increase aroma, and also provide some protection against oxidation. Masking agents that have been developed to cover other forms of off-flavors, such as metallic notes in high-intensity

Cooking of Meat | Warmed-Over Flavor sweeteners or beany notes in soybean products, have also been proven effective in masking WOF. Good masking agents will not have much flavor on their own when employed at low levels, but they are often coprocessed with compounds that impart desirable flavors (such as meaty flavor notes). Because the flavor can also mask certain desirable meaty notes if used at too high of a concentration, product testing is necessary to develop the best application level. Another option is that of simply disguising the oxidative notes. For example, the highly flavored systems, such as those found in spicy Mexican or East Indian seasonings, can distract the consumer from any off-notes, because the sensations of heat and tanginess dominate the consumers’ palate. Heavy spicing of meat products is common practice in countries where refrigerated storage is an issue. In developing a flavor system designed to combat WOF, it is important to consider the overall desired flavor profile of the finished product. Both temperature and hold time during the cooking process influence the overall taste. To achieve an optimal flavor, it is generally recommended that spices and flavoring agents be incorporated at a slightly higher level than would be needed for immediate consumption. Once an appropriate flavor system is developed, it is incorporated into the product by means of a mix-in seasoning, rub, or marinade, depending on the type of product formulated. In a whole-muscle product, marination is recommended to enhance protection and minimize the possibility of off-notes developing within the internal area of the product. As the product’s surface is more prone to oxidation than the interior of the meat, even topical application would still certainly help to minimize the formation of WOF notes.

See also: Cooking of Meat: Flavor Development; Heat Processing Methods; Maillard Reaction and Browning; Physics and Chemistry. Cutting and Boning: Traditional. Packaging: Modified and

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Controlled Atmosphere; Technology and Films; Vacuum. Smoking: Liquid Smoke (Smoke Condensate) Application

Further Reading Bauer, F., 2007. Fleisch und Fleischerzeugnisse − Oxidative Veränderungen bei Erhitzung und Fermentation. Die Ernährung 31, 505–509. Brannan, R.G., 2009. Effect of grape seed extract on descriptive sensory analysis of ground chicken during refrigerated storage. Meat Science 81, 589–595. Clausen, I., Jakobsen, M., Ertbjerg, P., Madsen, N.T., 2009. Modified atmosphere packaging affects lipid oxidation, myofibrillar fragmentation index and eating quality of beef. Packaging Technology and Science 22, 85–96. Grün, I.U., Ahn, J., Clarke, A.D., Lorenzen, C.L., 2006. Reducing oxidation of meat. Food Technology 60 (1), 37–43. Jayathilakan, K., Sharma, G.K., Radhakrishna, K., Bawa, A.S., 2007. Antioxidant potential of synthetic and natural antioxidants and its effect on warmed-overflavour in different species of meat. Food Chemistry 105, 908–916. Jittrepotch, N., Ushio, H., Ohshima, T., 2006. Effects of EDTA and a combined use of nitrite and ascorbate on lipid oxidation in cooked Japanese sardine (Sardinops melanostictus) during refrigerated storage. Food Chemistry 99, 70–82. Lund, M.N., Heinonen, M., Baron, C.P., Estévez, M., 2011. Protein oxidation in muscle foods: A review. Molecular Nutrition & Food Research 55, 83–95. O’Sullivan, M.G., Byrne, D.V., Jensen, M.T., Andersen, H.J., Vestergaard, J., 2003. A comparison of warved-over flavour in pork by sensory analysis, BC/MS and the electronic nose. Meat Science 65, 1125–1138. Pegg, R.B., Shahidi, F., 2000. Nitrite Curing of Meat: The N-Nitrosamine Problem and Nitrite Alternatives. Trumbull, CT: Food & Nutrition Press, Inc. Ross, C.F., Smith, D.M., 2006. Use of volatiles as indicators of lipid oxidation in muscle foods. Comprehensive Reviews in Food Science and Food Safety 5, 18–25. Sárraga, C., Carreras, I., García Regueiro, J.A., Guàrdia, M.D., Guerrero, L., 2007. Effects of α-tocopheryl acetate and β-carotene dietary supplementation on the antioxidant enzymes, TBARS and sensory attributes of turkey meat. British Poultry Science 47, 700–707. St. Angelo, A.J., Bailey, M.E. (Eds.), 1987. Warmed-Over Flavor of Meat. Orlando, FL: Academic Press, Inc. Tikk, K., Haugen, J.-E., Andersen, H.J., Aaslyng, M.D., 2008. Monitoring of warmedover flavour in pork using the electronic nose − Correlation to sensory attributes and secondary lipid oxidation products. Meat Science 80, 1254–1263. Tims, M.J., Watts, B.M., 1958. Protection of cooked meats with phosphates. Food Technology 12, 240–243.

CURING

Contents Brine Curing of Meat Dry Natural and Organic Cured Meat Products in the United States Physiology of Nitric Oxide Production Procedures

Brine Curing of Meat F Shahidi, Memorial University of Newfoundland, St. John’s, NL, Canada AGP Samaranayaka, POS Bio-Sciences, Saskatoon, SK, Canada RB Pegg, University of Georgia, Athens, GA, USA r 2014 Elsevier Ltd. All rights reserved.

Glossary Brine Salt solution possibly together with nitrite and other agents. Pickle curing Curing by dipping in brine. Salt meter Measures salt content of the brine or product in solution.

Introduction Curing is one of the oldest meat preservation processes known to man. Treating of meat with a solution of salt (sodium chloride), or packing the meat in dry salt, preserved the meat. Salt helped in preventing microbial spoilage and other deteriorative processes occurring in meat and fish for a considerable period through a decrease in water activity. The ancient Sumerians around 3000 BC were the first to make use of salt for meat and fish preservation. Dead Sea salt was used in ancient Palestine as early as 1600 BC. The Chinese and Greeks also used rock salt to preserve meat and are credited with passing this practice on to the Romans, who included pickled meats in their diet. As the use of salt from sea, desert, and rocks in preservation of meat spread, it was found that only certain types of salt helped in developing a desirable pink color and a special flavor in cured meat. Investigations in the nineteenth century revealed that sodium nitrate, present as an impurity in these salts, was the precursor responsible for developing the characteristic color and flavor in cured meat. Further, it was reported that nitrite, which was produced by microbial reduction of nitrate, was responsible for the curing effect. From subsequent experiments, it was proposed that the reaction of hemoproteins with nitric oxide (NO) derived from nitrite was the chemical basis for the color of cured meats. On the basis of

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Sea salt Salt from sea water. Warmed-over flavor Off-flavor note in reheated cooked meat, especially poultry meat.

these findings, the United States Department of Agriculture (USDA) regulated the use of sodium nitrite in meat curing in 1925. Present-day meat curing practice involves the intentional addition of sodium nitrite and salt to meat. Ascorbates or erythorbates are usually incorporated as cure accelerators. Other additives, such as sweeteners, phosphates/polyphosphates, seasonings (e.g., spices and herbs), smoke, and other nonmeat extenders, may be included in the curing mixture to impart characteristic properties to the end product. Curing methods can be divided into three main categories, namely, dry, direct addition, and wet (brine) curing. Dry curing is the oldest traditional technique in which the curing ingredients are rubbed onto the surface of the meat. For direct addition, curing ingredients are added to the meat during mixing or chopping of the meat product. In the brine curing process, the curing ingredients are dissolved in water to form a pickle or brine, which is introduced to or injected into the meat. Most of the processed meats available in North America today are cured in order to impart a desirable color, flavor, and texture plus a long shelf life to the end product. In addition, nitrite, together with sodium chloride, inhibits the formation of deadly neurotoxin by Clostridium botulinum. However, formation of N-nitrosamines from the reaction of nitrite with free amino acids and amines in some cured meat products, under certain heat processing conditions (e.g., high temperatures

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Curing | Brine Curing of Meat associated with frying of bacon), or in the stomach of the consumer is a particular concern. Thus, attempts have been made to lower the amount of nitrite used or to find alternatives to it in meat curing. Research in the latter area has concentrated on formulating multicomponent alternatives, as it was recognized that a single compound could not duplicate the multifunctional properties of nitrite.

The Chemistry of Meat Curing Although meat curing was originally used for preserving meat when it was plentiful, for use in times of scarcity, the need for preserving meat by curing alone has greatly diminished with the advent of sophisticated refrigeration and packaging techniques. Thus, the primary aim of present-day meat curing practices is to create flavor and appearance variations in food and to inhibit the outgrowth of C. botulinum spores. Another factor that has come to the forefront in modern curing practices is the increase of product yield and juiciness by incorporation of curing solutions. This can be achieved by using phosphates in the brine to increase the water-binding capacity of the meat by massaging and controlling other processing factors, such as smoking and cooking time, humidity, and the type of casing used.

Cured Meat Color NO is derived from the added nitrite (or nitrate) in the curing formula. It helps in fixation of cured meat color by stabilizing the muscle pigment myoglobin, [MbFe(II)], through a reversible chemical bond formation. Nitrite is the conjugate base of nitrous acid (HNO2). In an acidic environment, equilibrium is established between the ionized salt and the unionized nitrous acid, depending on the pH of the solution (pKa ¼ 3.4) (eqn [1]). HNO2 ⇌Hþ þ NO2−

½1

The concentration of HNO2 in cured meat is very low (0.1– 1.0%) at the usual pH values of meat (i.e., 5.5–6.5). Thus, the main reactive species in meat systems is dinitrogen trioxide (N2O3) (eqn [2]). 2HNO2 ⇌N2 O3 þH2 O

½2

In the presence of reducing agents (HRd), such as ascorbic acid or ascorbate, and endogenous reducing groups or compounds in meat tissue, such as cysteine, reduced nicotinamide adenine dinucleotide, cytochromes, and quinones, NO is formed from N2O3, as shown in eqns [3] and [4]. N2 O3 þ HRd ≡RdNO þ HNO2

½3

RdNO ≡Rd þ NO

½4

The NO molecule has the ability to form very stable complexes with metal ions, such as iron. Thus, NO reacts with meat pigments to form a red-colored nitrosylmyoglobin [MbFe(II)NO]. The oxidized pigment metmyoglobin [MbFe (III)] is formed by the oxidation of myoglobin after the addition of nitrite to the meat. MbFe(III) can then react with NO to form

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an intermediate pigment, nitrosylmetmyoglobin (Figure 1). Autoreduction of nitrosylmetmyoglobin pigment by the endogenous and exogenous reductants in the postmortem muscle tissue forms nitrosylmyoglobin. If MbFe(II) is present in meat after nitrite addition of nitrite, it can also react with NO to form MbFe(II)NO. However, formation of MbFe(II) NO in conventional curing occurs by the action of nitrite, as described in Figure 1. During thermal processing of cured meats, the globin moiety of nitrosylmyoglobin denatures and separates from the iron atom and surrounds the heme moiety to form nitrosylprotoheme or the cooked cured-meat pigment with a characteristic pink color. Figure 2 illustrates the formation of cooked cured-meat pigment and its possible side reactions during the curing process and subsequent storage. Salt (either sodium or potassium chloride) in the curing mixture accelerates the curing reaction owing to the formation of nitrosyl chloride (NOCl), which is a more powerful nitrosating species than N2O3 (eqn [5]). HNO2 þHþ þCl− ⇌NOCl þ H2 O

½5

A lower pH accelerates the formation of nitrosating species (N2O3 and NOCl). For this reason, acidulants (e.g., glucano-δlactone) are sometimes added to the formulation in order to accelerate the curing process. The cooked cured-meat pigment (i.e., nitrosylhemochrome) is quite stable to heat. However, the presence of light and oxygen may cause discoloration of cured meats. Proper packaging systems can be used to minimize product’s exposure to light (e.g., translucent films) and oxygen (e.g., vacuum packaging). Furthermore, mixing, massaging, and stuffing of cured meats must be performed under vacuum to exclude oxygen.

Cured Meat Flavor The characteristic flavor of cured meats is also due to the action of nitrite in the curing mixture. However, the chemical changes that are responsible for this flavor formation are not yet fully understood. The antioxidative role of nitrite in retarding the breakdown of unsaturated fatty acids and the formation of secondary lipid oxidation products may be the main processes involved in modifying the volatile profile of cooked cured meats by suppressing the formation of oxidation products, thus allowing the unique flavor associated with cured products to be revealed. In the pickle curing process, halotolerant bacteria, such as Vibrio spp., have also been shown to affect the flavor volatiles formed. Volatile compounds, such as 2-methylbutanal and 3methylbutanal, have been identified in meats cured with cover brines. These two compounds can react with hydrogen sulfide, ammonia, and ammonium sulfide in meat to form 3,5diisobutyl-1,2,4-trithiolane and 5,6-dihydro-2,4,6-triisobutyl4H-1,3,5-dithiazine, both of which are claimed to have cured meat aroma. Owing to the amount of salt used in most curing processes, salt plays a vital role in determining overall flavor of cured meats. In addition, smoking and added seasonings and sugar (especially in fried bacon) also participate in determining the characteristic flavor of different cured meat products.

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418

H N

H N

Protein

N H2C

C CH2 H

H3C N

N

H2C C CH2 H

H3C NO−2 + H+

N

Fe(II)

[NO]

HOOC

CH3

H3C

COOH

HOOC

H2O

N

OH

N Fe(III)

N

N

N CH3

H3C

COOH

HOOC

CH3 COOH ON

HO Metmyoglobin/MbFe(III)

Myoglobin/MbFe(II)

−

C CH2 H

H3 C

N

N

H3C

+

CH3

CH

Fe(III) N

N

CH3

H2C CH

Protein

N

N CH3

CH

H N

Protein

Nytrosylmetmyoglobin/MbFe(III)NO

Autoreduction

H N NO H2C

N

N

N

H2C C CH2 H

N

[NO]

Fe(II)

CH3

CH

H3C

C CH2 H

H3C

N

N H2C

CH3

CH

H N

.

Protein (or P )

N

N

N

H3C

CH3

H3C

HOOC

COOH

HOOC

OH

N

N Fe(II)

N

N CH3

H3C

COOH

HOOC

N CH3 COOH

ON

ON Cooked cured meat pigment + nitrite−protein complex

−

C CH2 H

H3C Reduction

Protein

CH3

CH

Fe(II)

Heat

.

Nytrosylmyoglobin/MbFe(II)NO

Nytrosylmyoglobin radical cation

Figure 1 A new mechanism for the meat curing process. Reproduced from Killday, K.B., Tempesta, M.S., Bailey, M.E., Metral, C.J., 1988. Structural characterization of nitrosylhemochromogen of cooked cured meat: Implications in the meat curing reaction. Journal of Agricultural and Food Chemistry 36, 909–914.

Curing Ingredients and Their Role in Cured Meats Salt (Sodium Chloride/Potassium Chloride) Salt is the main ingredient used in all curing mixtures and it is used for the purpose of developing flavor and for solubilizing proteins that are important for emulsion stability of comminuted and restructured meat products. Salt also helps in controlling microbial action in cured meats by lowering the water activity. Sodium chloride is the salt most commonly used in brine solutions, and its usage level varies with the type of product, being 1–2% in sausages, 2–3% in hams, 1.2–1.8% in bacon, and 2–4% in jerkies. Approximately 0.4–0.7% of potassium chloride on a finished-weight basis is used in lowsodium meat products, but it may impart bitter and metallic flavor if used at 40.75%.

Sodium Nitrite/Sodium Nitrate Sodium nitrite (or nitrate) is the most important cure additive responsible for the typical color and flavor associated with

cooked cured meats. It also provides oxidative stability to meat by preventing lipid oxidation and helps in controlling the development of warmed-over flavor in cooked, stored meats. Nitrite also serves as a vital bacteriostatic agent for control of the outgrowth of C. botulinum, particularly under conditions of product mishandling. However, addition of sodium nitrite to meat and meat products is highly regulated owing to the possible risk of formation of N-nitrosamine. In Canada, maximum allowable limit for the use of sodium nitrite, potassium nitrite, or their combinations in preserved meat and meat products (e.g., hams, loins, shoulders, cooked sausages, and corned beef) is 200 ppm (20 g per 100 kg; equivalent to 0.32 oz nitrite per 100 lbs raw batch). However, the industry has taken steps to reduce the level of nitrite used in such products to 120–180 ppm. In pumped bacon, in-going nitrite levels usually do not exceed 120 ppm (i.e., 0.19 oz nitrite per 100 lbs meat) owing to the possible risk of N-nitrosamine formation. These regulated levels are based on the amounts used in the product formulation before any cooking, smoking, or fermentation and are usually added as a cure salt, such as Prague powder.

Curing | Brine Curing of Meat

H N

H N

Protein

N

H3C

Oxidation

N

Reduction nitric oxide

H3C HOOC

H C CH2

H3C

N Fe(II)

N

N Fe(III) N

CH3

COOH

HOOC

COOH Metmyoglobin [MbFe(III), brown, Fe3+]

Protein denaturation and detachment Thermal processing

Protein denaturation and detachment Thermal processing

NO CH3

H2C CH H C CH2

N

CH3 H C CH2

H3C

N

Oxidation

N

N

Reduction nitric oxide

N

Fe(II) N

N

H3C

Nytrosylmyoglobin [MbFe(II)NO, red, Fe2+]

H3C

N

CH3 ON

H2C CH

CH3

H2C CH H C CH2

N

Protein

N CH3

H2C CH

419

N Fe(III) N

H3C

CH3

H3C

CH 3

HOOC

COOH

HOOC

COOH

Cooked cured meat pigment

Denatured metmyoglobin [brown, Fe3+]

[pink, Fe2+]

Oxidized porphyrins [green, yellow, colourless]

Figure 2 Some of the possible curing reactions that result from the addition of nitrite to meat. Reproduced from Bard, J., Townsend, W.E., 1978. Cured meats: Meat curing. In: Price, J.F., Schweigert, B.S. (Eds.), The Science of Meat and Meat Products, second ed. Westport: Food and Nutrition Press, pp. 452–470.

In the US, the Food Safety and Inspection Service (FSIS) regulations permit the use of sodium or potassium nitrite in all products except bacon at the following levels: 2 lb in 100 gallons of pickle at 10% pump or 200 ppm; 1 oz for each 100 lb of meat (60 g in 100 kg) in dry cure; and 0.25 oz per 100 lb meat or 156 ppm maximum in comminuted and (or) meat by-products. For immersion-cured and dry-cured bacon, in-going nitrite level limits according to FSIS are 120 and 200 ppm, respectively. Residual nitrite levels in the finished pumped bacon cannot exceed 40 ppm. Use of sodium or potassium nitrate as a curing agent is limited to some specialty products that require a long cure, such as dry-cured country ham and dry or semidry

sausages. For such specialty products produced in Canada, a maximum of 200 ppm of nitrate may be used in addition to the 200 ppm of nitrite. In the US, FSIS regulations permit the use of 3.5 oz of nitrate in 100 lb of meat (215 g per 100 kg) in dry-cured country ham, 700 ppm nitrate in pickle cure, and 2.75 oz of nitrate in 100 lb (170 g per 100 kg) chopped meat and (or) meat by-product.

Ascorbates/Erythorbates Ascorbic acid, isoascorbic (erythorbic) acid, and their respective salts are widely used in ham, bacon, and corned beef

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processing. Ascorbates are used in the curing process primarily to help improve and maintain the color (i.e., nitrosylhemochrome pigment) of cured meats. The primary function of ascorbic acid may be in reducing metmyoglobin to myoglobin, thus accelerating the overall curing reaction. Under suitable conditions, ascorbic acid also helps in the production of NO from nitrite or its derivatives in the curing mixture. Besides their role in color development, ascorbates and erythorbates have been shown to block the formation of carcinogenic N-nitrosamines in cooked cured meats (particularly in bacon). The USDA FSIS regulations permit the addition of 547 ppm of ascorbic or erythorbic acid, or the molar equivalent of their sodium salts, per 100 lb of chopped meat. For pumping pickle, the level is 75 oz of ascorbic acid or 87.5 oz of sodium ascorbate per 100 gallons (i.e., 469 ppm ascorbic acid or 547 ppm sodium ascorbate) when the pickle is to be used at a level of 10% of green weight (weight of raw meat used for curing before employing any treatments, such as pumping, tumbling, or cooking).

Sweeteners In addition to salt, nitrite, and nitrate, sugar is commonly used in the curing mixture. Sweeteners, such as table sugar (sucrose), brown sugar, dextrose, glucose solids, corn syrup solids, and lactose, can be added at different levels mainly to impart flavor and moderate the harshness of salt in certain products. Use of honey or maple syrup in small amounts during curing results in special flavor and aroma in cooked meats. Addition of reducing sugars (e.g., glucose solids and dextrose) to the brine also helps in browning reactions during thermal processing to produce a desirable color and a caramel flavor in some products, such as bacon. However, in some instances, the browning reaction may become too pronounced and could result in burned flavors and dark colors (e.g., rapid darkening of bacon on frying). Different levels of sugars, in the range 1–2%, are added to the brine during various commercial operations in order to lower the water activity of meat during curing and hence provide some preservative action in cured meats. When nitrates are used as curing agents, sugar enhances the growth of microorganisms that reduce nitrate to nitrite, the first step in the curing process.

Phosphates/Polyphosphates Phosphates and polyphosphates are used primarily to increase the water-holding capacity of cured meat products. Alkaline phosphates increase the pH of the meat and also help in solubilizing muscle proteins in order to impart the water retention action. In addition to increased water binding (i.e., increase in product yield), phosphates improve the cured meat flavor by retention of natural juices and by reduction of oxidative rancidity and warmed-over flavor in reheated meats by chelation of prooxidant metal ions. They also help to improve retention of the cured meat color. Phosphates that have been approved by the USDA for use in brine solutions include sodium acid pyrophosphate, monosodium phosphate, sodium hexametaphosphate, disodium

phosphate, sodium tripolyphosphate, and sodium pyrophosphate as well as mono- and dipotassium phosphate, potassium tripolyphosphate, and potassium pyrophosphate. These phosphates may be added to the pickle for ham, bacon, pork shoulders, picnics, Boston butts, boneless butts, and pork loins in the USA and Canada. Use of acidic and alkaline phosphates and blends of phosphates is restricted to 5.0% in the pickle and 0.5% (usually used at 0.3%) in the finished product. In addition, use of sodium hydroxide in combination with phosphate, in a ratio not to exceed 1 part sodium hydroxide to 4 parts of phosphate, was approved by the USDA for meat formulations where a higher pH is desirable and feasible. However, care must be exercised in the way sodium hydroxide is used. Tripolyphosphates and their combinations with hexametaphosphates are the most widely used phosphates for cured meat cuts, as they provide the proper pH, good solubility, calcium compatibility, and a high degree of protein-modifying effect. In some preparations, sodium acid pyrophosphate may be added to bacon and hams at a level of up to 0.5% to decrease pH and to accelerate cure development. However, acid phosphates are not typically used in sausage formulations, as a rapid pH decline can cause emulsion breakdown.

Seasonings Different types and levels of seasonings are used in curing mixtures by meat processors to impart unique flavors and appearance to meat products. These include spices and their extracts, herbs, hydrolyzed plant and vegetable proteins, and autolyzed yeast. The most common flavorings used in brine preparation are extracts from pepper, cloves, allspice, and cinnamon. Garlic and onion flavorings may also be added. An aqueous smoke solution is sometimes introduced into the curing pickle to provide a smoked flavor. In addition to flavoring properties, certain spices and herbs used as seasonings act as antioxidants by reducing the rate of oxidative rancidity development in cured meats.

Brine Curing Process Two fundamental procedures are used in meat curing: dry curing and brine curing. Although dry curing is the oldest method, brine curing has also been practiced for many years for the preservation of meat. In fact, a book dating from the reign of Augustus (63 BC to AD 14) contains directions for preservation of cooked meat in a brine solution containing water, mustard, vinegar, rock salt, and honey. The brine curing process uses the same ingredients as used in dry curing except that the cure mixture is dissolved in water to form a brine or pickle. In some cases, prepared brine may be used as a source of salt. Although the early application of curing used brines with high salt concentrations, mild cures with considerably lower salt concentrations are used in meat curing today due to the development of refrigeration techniques and owing to the trend toward reducing sodium consumption by healthconscious consumers. Present-day curing practices sometimes use a combination of dry curing and brine curing methods to produce certain specialty products.

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Brine Preparation

Table 1

A pickle cure may include: (1) water and salt (plain/salt pickle), (2) water, salt, and nitrite or nitrate, or (3) water, salt, nitrite or nitrate, and sugar (sweet pickle). Other ingredients, such as smoke, seasonings, ascorbates, and phosphates, may also be added to enhance or improve flavor and to speed up the curing process and increase product yield. The amount of green weight to be pumped and the equipment design (e.g., the size of the curing tank; the rate of processing; the capability of weighing and measuring; and the quantity of pickle retained in the injector reservoir) are important factors that should be considered in determining the amount of brine to be prepared. Brine should also be formulated in the near-exact amount to prevent pickle being left over, as the age of the brine is very critical to the nitrite level. Appropriate and accurate scales should be used in measuring and checking weights of cure ingredients. All measurements of solid ingredients used to prepare the brine should be by weight. Liquids, such as water, however, can be measured by volume. If ice is used in the preparation of brine, its weight must be used in all calculations. The order of mixing the curing ingredients to permit complete dissolution and to reduce the nitrite and ascorbate depletion during pickle preparation would be: (1) water; (2) phosphates; (3) ascorbate; (4) salt, sugar, and flavorings; and (5) nitrite. In most commercial curing operations, temperature of the curing room is held at 2–5 °C (36–40 °F) to retard bacterial growth during brine preparation and application and until salt penetration is complete. Experimental evidence indicates that a temperature near 0 °C is the optimal condition for the curing process and for storage of the curing pickles. Meat to be cured and water used in brine preparation should be cold enough (i.e., near 0 °C) to maintain the temperature of the brine and brine-treated meat close to 0 °C. At higher temperatures, microbial growth is accelerated. In addition, keeping the brine solution at temperatures above 15.6 °C for a long period in the air may result in oxidation of NO to the red nitrogen dioxide (NO2). Agitation may also hasten the reaction with oxygen. This process can reduce the extent of MbFe(II)NO production and hence the extent of color and flavor formation in cured meats. Thus, proper refrigeration and close monitoring of the temperature of the brine is necessary. In brine curing, brine preparation should be closely monitored and good sanitation maintained throughout the process. A salometer (a ballasted glass vacuum tube graduated in ‘degrees’) is used for testing the strength (density) or salinity of the pickle. If brine needs to be stored overnight, it must be kept cold and analyzed for nitrite and ascorbate before its use the next day. Curing tanks should be emptied and cleaned at least once a week to prevent growth of halophilic microorganisms.

Salt (kg)

Sugar (kg)

Sodium nitrite (g)

Cold water (l)

Degree of pickle by Salometer at 40 °F

4.5 4.1 4.5 3.6 3.6 2.7 3.2 2.7

1.4 1.4 1.4 1.4 1.4 1.4 1.4 1.4

7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5

15.1 15.1 18.9 15.1 18.9 15.1 18.9 18.9

95 90 85 85 75 70 65 60

Techniques of Brine Curing Pickle curing (immersion curing) In this process, meat products are immersed in brine until the cure ingredients penetrate the entire piece of meat. Sweet pickle with a salometer reading of 75–85° can be used for home curing; Table 1 lists the amounts of basic ingredients

Sweet pickle formulations

Source: Data calculated based on Romans, J.R., Costello, W.J., Carlson, C.W., Greaser, M.L., Jones, K.W., 1994. Meat curing and smoking. In: The Meat We Eat. Danville, CA: Interscience Publishers Inc., pp. 727−772.

necessary to make such pickles. The pickle curing method can be used for thick and thin cuts of meat and stainless-steel or selected plastic containers are used to store the meat during curing in order to avoid corrosion problems. Curing times prescribed for the different strengths of pickles listed in Table 1 are: 85° pickle, 9 days per inch; 75° pickle, 11 days per inch; and 60° pickle, 13 days per inch. Meat cuts with a higher thickness should be placed at the bottom of the curing barrel and the lighter ones placed on the top. Sufficiently cold (i.e., temperature close to 0 °C) pickle (usually 33 l per 100 kg (4 gallons per 100 lb) of closely packed meat and 37–42 l per 100 kg (4.5–5 gallons per 100 lb) of loosely packed meat) should be poured to cover the meat when the hold-down plate of the tank is weighted down. The thickness of each meat layer should be recorded in order to determine the date when the layers are to be taken out. It is desirable to overhaul (repack/move and turn) meat once or twice during the curing period in order to permit the pickle to reach all parts of the meat. The rate of diffusion of the curing ingredients depends on the size of the cut, the amount of fat covering, and the temperature during curing. As meat cuts used for curing can vary in size and ability to absorb brine, all parts of the meat may not absorb the same amount of cure. This is one disadvantage in using this process. Also, as brine penetration into meat cuts for the brine curing method is a relatively slow process and takes a fairly long time, spoilage can develop with large cuts of meat before curing is complete. Cure accelerators, such as ascorbates, are not used in brine solutions employed for pickle curing because the process is a fairly slow. However, alkaline phosphates can be used in pickle curing to retain the moisture in the meat. At present, this method is mostly used for curing of small meat items, such as tongues, corned beef, and hocks.

Pickle injection Owing to the problem associated with pickle curing (i.e., brine soaking), curing ingredients are now more commonly injected into the meat parts in order to obtain a rapid and uniform distribution of the cure throughout the tissue. Several techniques are used for this purpose, such as arterial pumping, stitch pumping, spray pumping, and multineedle injection.

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Arterial Pumping For meat cuts where the vascular system remains relatively intact (e.g., hams and tongues), brine solution can be introduced into meat through the arterial system. Pickle is pumped into the femoral artery on the inside butt end of the ham by means of a needle connected to a pump at a pressure of 275– 345 kPa (40–50 lbs per square inch). The strength of the brine (i.e., salt concentration) used in this process is usually approximately 65–80° salometers. Most commercial processes use a brine solution of 65° salometer and phosphates are also incorporated within regulatory levels to help water retention and to increase yield. Nitrite, instead of nitrate, is used in this method to obtain a level of 156 ppm nitrite in the injected product. Sugar is also incorporated into the brine at a prescribed level. Normally, arterial pumping adds 8–10% of brine by weight to the final product. It is advised to allow at least 24 h of refrigerated storage to permit not only equilibration of the cure but also fixation of the cured meat color. This is necessary because the vascular system is not uniform throughout the meat. However, this process is fairly slow, because pumping of brine has to be carried out carefully and gently in order to avoid bursting of arteries. It also requires a high labor input and careful handling during slaughter, cutting, and subsequent handling of meat cuts to ensure that the arteries remain intact and are not damaged. Uncured spots can develop in cured meat products, such as hams, due to damaged arteries.

Stitch and Spray Pumping Stitch pumping involves introduction of the brine into various parts of the meat tissues using a single-orifice needle. The spray pumping method is a variation of stitch pumping that uses a needle having several openings along the length of the needle to allow for a more uniform distribution of the pickle. Curing time is greatly reduced by this process as the curing ingredients diffuse from inside as well as outside of the cut. Also, the salt is introduced to the center of the ham cut before spoilage has a chance to take place. The brine strength varies depending on the amount of pickle to be pumped into the meat, the desired intensity of salty flavor, and the storage conditions. In normal commercial operations, approximately 65° salometer brine with 150 ppm nitrite and adequate alkaline phosphate is used for injection at approximately 10% by weight. The injections are usually made at several sites, as close together as possible. However, uniform distribution of the cure is greatly dependent on the operator and, with bone-in meat parts (e.g., bone-in ham), it is difficult to distribute the cure uniformly around bones. Thus, stitched meat cuts should be held under refrigeration, perhaps in a cover pickle, for 5–7 days to allow uniform distribution of the cure.

Multineedle Injection This method is widely used in the industry for curing bacon and pork cuts, both bone-in and boneless. This process is very rapid, continuous, and cost effective and reduces the number of workers involved during the curing process. The principle is quite similar to the stitch pumping method but uses 100–250

stainless-steel needles at uniform distances for injection of the brine. A series of offset needles are used in most commercially available machines and, on activation, pickle is pumped until the desired weight is obtained. This process helps to achieve a rapid and uniform distribution of the cure. The quantity of brine injected can be controlled by adjusting belt speed and number of strokes per minute. Independently balanced and functioning needles permit brine injection to follow the configuration of the meat cuts more closely. The pumping pressure must also be carefully controlled to avoid muscle tissue damage, loss of cure retention, and formation of open pockets of pickle in the meat. In addition, all air should be removed from the pumping system, or vacuum pumping should be used, to avoid incorporation of air into the product. Needles must be periodically checked and cleaned to insure uniform pumping and to avoid bacterial contamination. However, if microbes are present on the surface of a meat cut, they can pass into the interior of the meat during injection. More importantly, as this is a continuous operation (injection of several meat cuts per cycle), contamination can occur from one piece of meat to another. Thus, good sanitation practices are necessary during this process. Some processors recirculate the brine during multiple injections, and this can also result in recontamination. Fresh brine should be used for each batch of meat cuts when using this method.

Massaging and Tumbling Physical processes, such as massaging and tumbling, are used for brine-treated meat cuts to draw out water-soluble proteins (mainly actomyosin) to the meat surface and enhance the overall water-binding capacity when the exuded proteins gel on heating. Simultaneously, massaging and tumbling result in an increase in the internal tissue temperature that increases penetration and distribution of the brine. These mechanical treatments have been shown to shorten the curing period to 24 h, partly by aiding the distribution of the curing salts. Vacuum tumblers are used to overcome problems of tissue softening and incorporation of air and thus foaming of the protein matrix that has been brought to the surface during tumbling. Some tumblers have brine injection needles built into the vacuum chamber to allow simultaneous injection and mechanical action.

Smoking, Cooking, and Drying of Brine-Cured Meats Smoke, generally produced by slow combustion of sawdust from hardwood (consisting of approximately 40–60% cellulose, 20–30% hemicellulose, and 20–30% lignin), inhibits bacterial growth and lipid oxidation and imparts flavor to cured meat. Many cured meat products are smoked in order to achieve these objectives. The cooking step is important for cured meats for fixation of the characteristic cured meat color (i.e., formation of nitrosylhemochrome pigment) and flavor. Cooking and smoking are often carried out simultaneously. Either steam or gas can be used for cooking. The cooking and smoking cycle must be carefully controlled to obtain the desired color, flavor, yield, and destruction of microorganisms in the brine-treated meats. The temperature and time of cooking,

Curing | Brine Curing of Meat as well as the humidity, are the most important parameters to be controlled. The final temperature depends on the product and is expressed as the internal temperature achieved for the finished product. The USDA regulations require that the fully cooked meat products attain a minimum temperature of 64 °C. However, drying, one of the earliest forms of meat preservation, remains in use for the production of dry or semidry fermented sausages.

Critical Control Factors during the Brine Curing Process During meat curing, the composition of the curing mixture (such as the amount of nitrite, ascorbate, and phosphates) and the processing conditions (such as curing time, order of mixing of curing ingredients, and temperature during curing) should be controlled to achieve the desired color and flavor in the cured meats. It must also be considered that the intensity of the cured meat color depends on the availability of meat pigments (i.e., myoglobin) to form nitrosylmyoglobin during curing. A more intense cured color will thus be achieved for corned beef, containing more heme pigments than that for cured ham, when the same amount of nitrite is added. Nitrite in the brine exerts an antimicrobial effect and retards the formation of C. botulinum toxin. Salt also helps in controlling microbial growth in cured meats by lowering the water activity. Combination of the practices used commercially for production of safe cured meat include addition of sodium nitrite at an initial concentration of 75–150 ppm with a residual concentration of 20 ppm or more, a sodium chloride concentration of 1.5–2.0% (both on a product basis), heating of the product to approximately 71 °C, and maintenance of a good sanitation throughout the curing process in order to minimize bacterial contamination. In addition, cured meats must be stored at temperatures below 10 °C. Water used for the preparation of brine should be potable and free from bacteria, as bacteria can interfere with the curing reactions. The use of chlorinated water can adversely affect cured meat flavor. Food-grade salt should be used for brine preparation to insure a good flavor and color. Trace impurities in salt, such as copper, iron, and chromium, can catalyze oxidative reactions in cured meat products. Phosphates added to the brine help by chelating metal ions in the brine and reduce their catalytic activity in flavor deterioration. During brine preparation, phosphates should be dissolved in water before the addition of salt, as the salt can reduce their solubility. If the level of phosphates in the brine is too high, or if the salt concentration is too high, phosphates may precipitate, hence reducing their effectiveness. Thus, the proportions of phosphates and salt added to the brine should be properly controlled. Another problem in using phosphates is the formation of disodium phosphate crystals on the surface of the cured products owing to the loss of moisture during the processing and storage of cooked cured meat products. This problem can be overcome by reducing the level of phosphates in the brine, maintaining adequate humidity during processing, and using proper packaging systems to reduce moisture losses during subsequent storage. Owing to the corrosive nature of phosphates, another critical point with phosphates is

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the use of stainless-steel or plastic equipment and containers for brine processing of meat. Levels of nitrite used in cured meats should be within the regulatory limits in order to reduce possible risk of Nnitrosamine formation. Formation of compounds such as Nnitrosopyrrolidine has been found to occur in bacon when frying at high temperatures. Thus, a maximum/minimum level of 120 ppm sodium nitrite is used for bacon curing. Bacon should also contain the maximum permitted level (547 ppm) of ascorbate or erythorbate in order to reduce N-nitrosamine formation. Use of buffered curing premixes containing nitrite, seasonings, and other flavorings is no longer permitted due to the risk of N-nitrosamine formation. Nitrite and nitrate are packaged separately from flavorings and seasonings in commercial curing mixes, and these separately packaged ingredients are not to be combined until just before use. Nitrite and nitrate must be uniformly mixed with other cure ingredients in order to avoid unexpected problems due to the presence of toxic levels of ingredients in any product batches.

Sodium Reduction in Brined Products High sodium intake has been associated with increased risk of hypertension. To reduce sodium intake, there are three ways to lower the content of sodium chloride in processed meats. The first is to partially replace sodium chloride with potassium chloride; it is the most commonly used process to date. However, potassium chloride has a slightly bitter taste and other substances may have to be added in order to mask this unwanted taste. In this connection, lysine hydrochloride may be used at approximately 1% in such products. Second, flavor enhancers may be added to the meat, although their combination with salt has proven to provide a salty taste. Third, the physical structure of sodium chloride can be changed so that a lower concentration of it can still provide the same salty taste. This method is still being studied.

Nitrite Reduction Nitrite renders multiple effects in cured meats by preventing oxidation and allowing the true flavor of meat to reveal itself. It also produces a desirable color in cured meat products and inhibits microbial growth. Because of its efficiency, nitrite is very difficult to replace; therefore, the common practice is to reduce its level and add other substances to mimic its properties. To inhibit lipid oxidation, antioxidants, such as spices like rosemary extracts, are added. Many of these antioxidants also have multiple benefits, such as antimicrobial effects. However, simply changing the food packaging and preparation procedures to reduce the meat’s exposure to light and oxygen can help to reduce the lipid oxidation and production of free radicals, hence retaining the desirable flavor and color of the meat. To mimic the multiple preservative effects of nitrite, different ingredients with varying effects must be added. Ingredients with naturally high nitrate content are useful preservatives, as nitrate can be reduced to nitrite with naturally occurring nitrate-reducing bacteria. Such ingredients include vegetables, such as celery and spices. Use of celery juice in production of the so-called nitrite-free meat products has

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Curing | Brine Curing of Meat

taken place, but products may contain higher levels of residual nitrite than their nitrite-cured counterparts. Another way to preserve meat without nitrite is to add antimicrobials, including spices, herbs, and their oils. However, such antimicrobials usually only inhibit the growth pathogens and food-spoiling organisms in one way, whereas nitrite inhibits their growth in multiple ways. For this reason, different types of antimicrobials are needed to duplicate the effect of nitrite.

Summary Although the origin of meat curing is lost in antiquity, the empirical observation that salting can preserve meat was made several thousand years ago. The occurrence of nitrate impurities in rock salt was found to be responsible for color formation in cured products. Present-day meat curing practices use a mixture of salt (sodium and/or potassium chloride); nitrite (or nitrate in some specialty products); sugar; cure accelerators, such as ascorbates or erythorbates; curing adjuncts, such as phosphates; seasonings; and other nonmeat ingredients in regulated levels. Dry curing, direct addition, and brine curing are the three fundamental procedures used in meat curing. Brine curing uses the same ingredients as in dry curing and direct addition (perhaps at different levels to achieve adequate curing), but the ingredients are dissolved in pure water in order to produce a pickle that can be used in pickle curing or injected into the meat cuts. Methods for brine injection can be arterial, stitch, or multineedle injection. Each of these methods has its own advantages and disadvantages. Most industrial curing processes use the multineedle injection method because it facilitates rapid curing and faster production rate (i.e., number of meat cuts pumped per minute). However, there are some critical control factors to be considered during brine preparation, injection, maturation, and thermal processing of meat in order to obtain the desired color, flavor, and microbial quality of

cooked, cured products. Furthermore, the issue of sodium reduction is a recent interest in preparation of processed meat products.

See also: Cooking of Meat: Flavor Development; Warmed-Over Flavor. Curing: Dry; Production Procedures. Ethnic Meat Products: North America. Processing Equipment: Brine Injectors; Smoking and Cooking Equipment; Tumblers and Massagers. Smoking: Traditional

Further Reading Armenteros, M., Aristoy, M.-C., Barat, J.M., Toldra, F., 2012. Biochemical and sensory changes in dry-cured ham salted with partial replacement of NaCl by other chloride salts. Meat Science 90, 361–367. Holland, G., 1983. Curing of ham and smoked meats-the state of art. The National Provisioner, March 5, 6−13. Pegg, R.B., Shahidi, F., 2000. Nitrite curing of meat. The N-Nitrosamine Problem and Nitrite Alternatives. Trumbull: Food and Nutrition Press Inc. Romans, J.R., Costello, W.J., Carlson, C.W., Greaser, M.L., Jones, K.W., 1994. Meat curing and smoking. In: The Meat We Eat. Danville, CA: Interstate Publishers Inc., pp. 727−772. Townsend, W.E., Olson, D.G., 1987. Cured meats and cured meat products processing. In: Price, J.F., Schweigert, B.S. (Eds.), The Science of Meat and Meat Products, third ed. Westport: Food and Nutrition Press Inc., pp. 431–456. Shahidi, F., 1992. Prevention of lipid oxidation in muscle foods by nitrite and nitrite-free compositions. In: St. Angelo, A.J. (Ed.), Lipid Oxidation in Food. Washington, DC: American Chemical Society, pp. 161–182. ACS Symposium Series 500. Shahidi, F., Rubin, L.J., D’Souza, L.A., 1986. Meat flavour volatiles: A review of the composition, techniques, analyses and sensory evaluation. Critical Reviews in Food Science and Nutrition 24 (2), 141–243. Skibsted, L.H., 1992. Cured meat products and their oxidative stability. In: Ledward, D.A., Johnston, D.E., Knight, M.K. (Eds.), The Chemistry of Muscle Based Foods. Cambridge, UK: Royal Society of Chemistry, pp. 266–286. Weiss, J., Gibis, M., Schuh, V., Salminen, H., 2010. Advances in ingredient and processing systems for meat and meat products. Meat Science 86 (1), 196–213.

Dry F Toldrá, Instituto de Agroquímica y Tecnología de Alimentos (CSIC), Valencia, Spain r 2014 Elsevier Ltd. All rights reserved. This article is a revision of the previous edition article by F Toldrá, volume 1, pp 360–366, © 2004, Elsevier Ltd.

Glossary Decarboxylases Enzymes able to transform an amino acid into an amine. Glycolysis Enzymatic breakdown of carbohydrates with the formation of pyruvic acid and lactic acid and the release of energy in the form of ATP. Lipase Enzyme that catalyzes the release of fatty acids by hydrolysis of triacylglycerols at positions 1 and 3. Lipolysis Enzymatic breakdown of lipids with the formation of free fatty acids.

Introduction The origin of dry cured meats is lost in ancient times and the processing of these products is varied depending on the particular customs and habits of each country. Dry cured ham constitutes one of the main and representative products obtained through dry curing. Consumption of dry cured ham is typical in Mediterranean countries where it is produced in substantial amounts (i.e., more than 30 million pieces per year in Spain). Some of the most well-known products are Spanish Iberian and Serrano hams, French Bayonne ham, Italian Parma and San Danielle hams and Portuguese presunto. Other dry cured hams produced in China are the Jinhua ham, Xuanwei ham and Rugao ham. In some cases, hams are submitted to short processes and smoked like the American Country-style and German Westphalia hams. In the European Union, the most famous hams are protected by designations of origin, being controlled by consortiums that guarantee the authenticity and quality of their products. Dry curing consists of the application of a dry cure (no water added) containing salt, nitrate and/or nitrite and other agents like sugar and ascorbic or erythorbic acids. The process involves several stages: (1) a salting stage for the penetration of salt into the product by solubilization in the moisture of the meat, (2) a postsalting for salt diffusion and equalization through the entire piece and (3) a drying/ripening stage for water loss and development of numerous biochemical reactions affecting color, texture, and flavor. Dry curing is a traditional process, where the knowledge of the process has been transmitted from generation to generation. However, the need to obtain products of constant high quality, based on reproducible and controlled production processes, has prompted a considerable amount of scientific and technical research over the past 25 years. Today, there is a considerable amount of information available on the biochemical mechanisms involved in the process. Proteolysis and lipolysis constitute two groups of enzymatic reactions directly affecting protein and lipids, respectively, and resulting in important contributions to flavor and texture development.

Encyclopedia of Meat Sciences, Volume 1

Proteases Enzymes that catalyze the release of an amino acid from the amino terminus of a peptide (exopeptidases) or able to hydrolyze myofibrillar proteins to polypeptides (cathepsins and calpains). Proteolysis Enzymatic breakdown of proteins with the formation of peptides and free amino acids. Water activity (aw) Indication of the availability of water in a food and is defined as the ratio of the equilibrium water vapor pressure over the system to the vapor pressure of pure water at the same temperature.

Proteins and lipids constitute the major chemical components of dry cured meat products, and their breakdown products are essential for flavor and texture.

Proteolysis Proteolysis constitutes one of the most important groups of reactions responsible for degradation of sarcoplasmic and myofibrillar proteins and further hydrolysis of the generated polypeptides and peptides to small peptides and free amino acids. Skeletal muscle contains a wide variety of enzymes able to hydrolyze either internal peptide bonds (cathepsins and calpains) or peptide chains from their ends (tri- and di-peptidylpeptidases and aminopeptidases). Most of the enzymes are located in lysosomes, in the myofibrillar structure or bound to membranes, and have optimal pH near the values typically found in dry cured meats.

Action of Proteases During Dry Curing The long processing time, several months or even years, allows for an intense action of muscle proteases. In general, these enzymes are quite stable and thus able to act for long periods of time. There are some exceptions like cathepsin D that tends to disappear approximately the sixth month of processing, and calpains which are restricted to the initial 2 weeks of the process owing to their rather poor stability. The full flow chart for the proteolysis during dry curing is shown in Figure 1. Initially, major protein breakdown, mostly due to calpains, is focused on Z-disc proteins, desmin and other major proteins like titin and nebulin. However, calpains are unstable and further protein breakdown, observed during the entire process, is due to cathepsins, especially cathepsins B and L. Polypeptides that are generated are further hydrolyzed to peptides within the range 2700–4500 Da, and most of those are further hydrolyzed to smaller peptides (below 1200 Da),

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426

Curing | Dry

Muscle proteins

Cathepsins and calpains Polypeptides Peptidases Peptides Nonvolatile taste compounds

Fur the

r reacti

ons

Volatile aroma compounds

Aminopepticlases ns

tio

er

Free amino acids

r th

c rea

Fu

Figure 1 Flow chart showing the major important steps in muscle proteolysis during the processing of dry cured meats. Reprinted from Toldrá, F., 1998. Meat Science 49, s101–s110.

especially tripeptides and dipeptides by tripeptidylpeptidases and dipeptidylpeptidases, respectively. Peptide mappings, analyzed at different stages by reverse-phase HPLC and capillary electrophoresis, have confirmed the generation and/or increase of numerous peptides that have been further fractionated by size and fully sequenced by proteomics techniques. Savory fractions have been shown to be related to peptides within the range 1500–1700 Da. The generation of free amino acids by aminopeptidases constitutes the last step in the proteolysis chain. Some amino acids, mainly glutamic acid, alanine, leucine, lysine, valine and aspartic acid, are abundantly generated reaching amounts as high as 50–350 mg per 100 g of product by the end of the process. Alanyl aminopeptidase is the main exopeptidase involved in this process as it is the major aminopeptidase in muscle and has a wide substrate specificity. However, the generation of basic amino acids, arginine and lysine, is mainly due to aminopeptidase B. In general, the longer the process, higher is the amount of free amino acids generated. The combination of peptides and free amino acids together contribute to the characteristic taste of the product. Proteolysis is important in dry curing and has many benefits for the final quality of the product although it needs to be controlled as an excess of proteolysis may impair the sensory characteristics and result in poor ratings by sensory panelists and consumers for the following reasons: (1) an excessive accumulation of low molecular weight nitrogen compounds (peptides and free amino acids), enhancing a bitter and metallic taste, (2) the presence of randomly distributed white crystals of tyrosine, making the product less attractive, and (3) excessive breakdown of myofibrillar proteins resulting in an undesirably soft product.

Lipolysis The process of lipolysis can be considered as a group of enzymatic reactions affecting triacylglycerols and phospholipids.

Lipids

Triglycerides

Phospholipids

Lipases

Phospholipases

Free fatty acids Oxidation Radiations, heat, ions,... oxidative enzymes,...

Peroxides Further reactions Interactions with peptides, amino acids,... secondary oxidation products,...

Volatile aroma compounds Figure 2 Flow chart showing the major important steps in muscle lipolysis and oxidation to volatile compounds during the processing of dry cured meats. Reprinted from Toldrá, F., 1998. Meat Science 49, s101–s110.

Free fatty acids are released in these reactions and act as precursors of further oxidative reactions leading to volatile aroma compounds as shown in Figure 2. Lysosomal acid lipase and neutral lipase are present in skeletal muscle and are able to hydrolyze tri- and di-acylglycerols at acid and neutral pH, respectively, and generate free fatty acids. Acid phospholipase also generates free fatty acids acting on phospholipids as substrate. Lysosomal acid lipase and acid phospholipase are located in lysosomes and have optimal pH near the pH values usually found in dry cured meats. Furthermore, both enzymes have shown good stability along the full process. The activity of lipases and phospholipases is higher in oxidative muscles than in glycolytic muscles. Acid and neutral esterases are also present in muscle tissue but the generation of short chain free

Curing | Dry fatty acids is almost negligible suggesting that these enzymes have a minor role. In addition, esterase activity remains unaffected by the oxidative pattern of the muscle. Hormone-sensitive lipase and mono-acylglycerol lipase are located in adipose tissue and are active at neutral pH. These lipases find good conditions for activity during dry curing and are responsible for the generation of free fatty acids from triacylglycerols and diacylglycerols and from monoacylglycerols, respectively.

Action of Lipases During Dry Curing The rate of lipolysis is fast during the first 6 months but then decreases, reaching slower rates toward the end of the process. A great percentage of the generated free fatty acids in muscle occurs as a result of phospholipid hydrolysis, indicating a major role of phospholipases. In fact, the hydrolysis of phospholipids is very important for the final flavor of the product because they release long chain polyunsaturated fatty acids which are very sensitive to oxidation. Fatty acid profiles during the processing of dry cured meats usually reaches a maximum at some point but, before the end of the process, oxidation results in a decrease in long chain polyunsaturated fatty acids. Oxidation is favored by the presence of salt, action of oxidative enzymes like muscle lipoxygenases and cycloxygenases, drying/ripening temperatures, and long time for reactions. The minor amount of lysophospholipids can be explained by the high activity of lysophospholipases in relation to phospholipases. Triacylglycerols are hydrolyzed and also provide a significant amount of free fatty acids although at a lower rate. In this sense, the disappearance of triacylglycerols is correlated with the increase in di- and monoacylglycerols, as products of the hydrolytic action. Triacylglycerols from adipose tissue also undergo an intense lipolysis during the salting and postsalting stages, with a substantial increase in free fatty acids. Hormone-sensitive lipase that remains active during the full ripening/drying period is the main enzyme responsible for lipolysis in the adipose tissue. Monoacylglycerols are further degraded to glycerol and the respective fatty acid by the mono-acylglycerol lipase. The generation rate, especially in mono and polyunsaturated fatty acids depends on the composition of the feed given to the pigs. This is of extreme importance for oxidative reactions that will generate different volatile compounds, and thus different aromas, depending on the composition in fatty acids.

Nucleotides Degradation During Dry Curing Nucleotides experience an intensive enzymatic degradation during the dry curing process until almost complete disappearance at approximately 7 months. On the contrary, hypoxanthine and xanthine, as final products of the enzymatic cascade, are generated primarily during the first 7 months of dry curing, and remain for the rest of process. Hypoxanthine, which is generated at more than 15 µmol per gram of dry matter, might be considered as a potential biochemical marker of a minimum time of processing (7 months) in view of its evolution and stability.

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Curing Factors Affecting Muscle Enzyme Activity Curing agents and processing conditions exert different effects on the activity of muscle enzymes. Salt is a basic compound in dry curing processes and exerts a clear and important influence on muscle enzymes. Cathepsins D and H, dipeptidylpeptidases II and III and alanyl aminopeptidase are strongly inhibited by salt whereas calpains, aminopeptidase B, and lysosomal acid lipase are slightly activated, especially at low salt levels. Other curing agents like nitrate and nitrite, glucose, or ascorbic acid exert only a slight effect on the enzyme activity. Conditions such as temperature during drying and ripening are favorable for enzyme activity. However, the slightly acid pH of meat reduces the activity of strictly acid enzymes (i.e., cathepsin D) and neutral/basic enzymes (i.e., calpains, leucine and pyroglutamyl aminopeptidases, neutral lipase and esterase).

Microbial Evolution Low bacterial counts are usually found inside the hams due to limiting factors like salt concentration, presence of nitrite and progressive water activity reduction. Microorganisms present in the natural flora of ham include Lactobacillus sakei, Lactobacillus curvatus and Pediococcus pentosaceus. They have good exo-proteolytic activity although its contribution to proteolysis is minimal owing to the low counts. Staphylococcus xylosus is also naturally present and has an important nitrate reductase activity that contributes to the reduction of nitrate to nitrite. Amines might be generated by decarboxylation of certain free amino acids as a consequence of undesirable bacterial growth having decarboxylase activity although low or negligible levels are usually found. Humidity and temperature must be taken into account, particularly in the air-conditioned rooms, to avoid growth and development of molds, usually Penicillium, and sometimes yeasts such as Candida zeylanoides and Debaryomices hansenii, on the outer surface of the hams.

Sensory Characteristics Color The intensity of color depends on the concentration of myoglobin, which varies depending on the type of muscle (myoglobin concentration is higher in muscles with oxidative pattern) and the age of the animal (myoglobin concentration tends to be higher in muscles from older animals). Nitrosomyoglobin is generated through the reaction of nitric oxide with myoglobin when nitrate and/or nitrite have been used, giving hams a typical bright-red cured color. Those hams without added nitrate or nitrite like Parma hams present a pink-red color that is attributed to the Zn protoporphyrin IX complex. Dark colors on the surface of the hams are typical after smoking treatment.

Texture Proteolysis of key myofibrillar and associated proteins is responsible for tenderization. An intense degradation of the

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myofibrillar structure is observed during dry curing. Major structural proteins like titin, nebulin, and troponin T as well as myosin heavy chain and α-actinin are severely proteolyzed. Two clear fragments corresponding to 150 and 85 kDa appear along the processing. Hams produced from pale, soft, exudative (PSE) meats show an absence of these fragments when compared to normal hams and there is a trend toward softer hams. In fact, the application of a texture analysis shows that PSE hams have lower hardness, springiness, cohesiveness, and chewiness values. Texture of the product depends not only on the extent of myofibrillar protein breakdown but also on other factors like the extent of drying, the degradation of the connective tissue and the content of intramuscular fat which also exerts a positive influence on some texture and appearance traits.

Flavor Flavor generation is strongly associated with the proteolysis and lipolysis phenomena. Taste is mainly associated with nonvolatile compounds accumulated by the end of the process (see Table 1) and, in fact, the concentration and composition of free amino acids and small peptides at the end of dry curing has been related to specific taste descriptors. For instance, the composition of peptides in savory fractions consisted of glutamic acid, glycine, alanine, valine, proline, histidine, and leucine. However, lysine and tyrosine have been correlated with aged taste whereas glutamic acid, aspartic acid, methionine, phenylalanine, tryptophan, lysine, leucine, and isoleucine have been correlated with the length of the drying and the fully ripened ham taste. The excessive accumulation of tryptophan, tyrosine and phenylalanine, in hams with a high level of proteolysis, is associated with a bitter taste. Nucleotides are strong taste enhancers but their concentration in dry cured meats is very low and in most of the cases below the Table 1

sensory threshold value, and thus its contribution can be considered almost negligible. Only hypoxanthine, which is generated at concentrations higher than 15 µmol g−1 dry matter, may contribute to bitter taste. In the case of aroma, nearly 200 volatile compounds, most of them with impact on aroma perception, have so far been reported in dry cured meats. They are representative of most classes of organic compounds such as aldehydes, alcohols, hydrocarbons, pyrazines, ketones, esters, lactones, furans, sulfur and chloride compounds, carboxylic acids, etc. Some of these compounds are generated through oxidation of unsaturated fatty acids resulting from lipolysis, as shown in Figure 2. The generation of free amino acids like pyrazines, sulfide compounds, and branched-chain aldehydes during dry curing constitutes an important source of volatile compounds with important aromatic characteristics. The most representative classes of volatile compounds found in dry cured meats and the main routes for generation are listed in Table 2. The final flavor strongly depends on the specific aromas and odor thresholds for each particular volatile compound. In general, pleasant aroma is correlated with the presence of certain ketones, esters, aromatic hydrocarbons, and pyrazines.

Processing Control The ability to control this complex system in a dry cured product is very important for economical and quality reasons. There are several ways to control the proteolytic and lipolytic activity in the hams: (1) the genetics and age of pigs exert a clear influence on the final quality of the products. Different enzyme profiles and composition have been detected depending on the specific crossbreed and age. The amount of lipids and marbling, very important for the sensory quality of the final product, also depend on the breed (i.e., the Duroc

Major nonvolatile compounds generated or present in dry cured meats and the relative contribution of each to taste

Groups

Main compounds

Contribution to taste

Peptides Free amino acids Free fatty acids Nucleosides Inorganic compounds

Many tri and dipeptides, carnosine and anserine Lysine, glutamic acid, aspartic acid, leucine, alanine, arginine, valine, serine, threonine, … 18:1 n−9, 18:2 n−3, 16:0, 18:0, 20:4 n−6, 18:3 n−6, … Hypoxanthine, xanthine Sodium chloride

High High Low Low/medium High

Table 2 flavor

Major classes of volatile compounds generated in the processing of dry cured meats and the relative contribution of each to final

Groups of volatile compounds

Main routes for generation

Odor threshold

Contribution to flavor

Aliphatic hydrocarbons Aromatic hydrocarbons Aliphatic aldehydes Branched-chain aldehydes Alcohols Ketones Esters Pyrazines Sulfide compounds

Lipids auto oxidation Oxidative decomposition of lipids Oxidation of unsaturated fatty acids Strecker degradation of valine, leucine, and isoleucine Oxidative decomposition of lipids Lipid oxidation Interaction of carboxylic acids and alcohols Maillard reactions Strecker degradation of sulfur-containing amino acids

High High Low Low High Low Low Low Low

Very little Low High High Low High High Medium Medium

Curing | Dry breed gives more intramuscular fat than many others) and age (i.e., higher lipids content as animal gets older), (2) the feed, especially the lipid composition in fatty acids, strongly affects the composition of pork fat and thus the final aroma of the dry cured meat because many volatile compounds arise from the oxidation of particular unsaturated fatty acids, (3) processing control of important parameters like temperature, relative humidity and air speed in computer-controlled curing rooms are important for drying and subsequent water loss from the product. The reduction in water activity affects enzymatic hydrolysis reactions, like proteolysis and lipolysis, lowering the rate of hydrolysis, and (4) the addition of salt affects muscle enzymes. Based on its proved inhibitory effect on cathepsins, salt may be used to prevent an excessive tenderness when using hams from pigs with high levels of cathepsin activity. The excess of cathepsin activity may be controlled in the raw material through rapid test kits and, in those cases with an excessive activity, the addition of an excess of salt constitutes an effective controlling measure because its inhibitory effect on cathepsins results in a slower protein breakdown.

Salt Reduction Dietary intake of excessive amounts of sodium may have negative effects on the cardiovascular health of the consumers and following such medical concern, the meat industry has made serious efforts in recent years to reduce salt content in hams. The strategies to reduce the amount of salt used in the processing of dry cured ham consist of a direct reduction in the amount of added salt and/or partial replacement of sodium chloride by other chloride salts like potassium chloride, calcium chloride, and magnesium chloride. However, the percentage of replacement is restricted to less than 40% due to bitterness associated with an excess of potassium or metallic aftertastes associated with the presence of certain levels of calcium and magnesium.

See also: Chemical Analysis: Raw Material Composition Analysis; Standard Methods. Chemical and Physical Characteristics of

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Meat: Water-Holding Capacity. Curing: Production Procedures. Drying. Ham Production: Dry-Cured Ham. Sausages, Types of: Dry and Semidry. Sensory Assessment of Meat

Further Reading Armenteros, M., Aristoy, M.C., Barat, J.M., Toldrá, F., 2011. Biochemical and sensory changes in dry-cured ham salted with partial replacement of NaCl by other chloride salts. Meat Science 90, 361–367. Flores, M., Spanier, A.M., Toldrá, F., 1998. Flavour analysis of dry-cured ham. In: Shahidi, F. (Ed.), Flavor of Meat, Meat Products and Seafoods. London: Blackie Academic & Professional, pp. 320–341. Hernández-Cázares, A.S., Aristoy, M.C., Toldrá, F., 2011. Nucleotides and their degradation products during processing of dry-cured ham, measured by HPLC and an enzyme sensor. Meat Science 87, 125–129. Ripollés, S., Campagnol, P.C., Armenteros, M., Aristoy, M.C., Toldrá, F., 2011. Influence of partial replacement of NaCl for KCl, CaCl2 and MgCl2 in lipolysis and lipid oxidation in dry-cured ham. Meat Science 89, 58–64. Toldrá, F., 1998. Proteolysis and lipolysis in flavour development of dry-cured meat products. Meat Science 49, s101–s110. Toldrá, F., 2002. Dry-cured meat products. Trumbull, CT: Food & Nutrition Press. Toldrá, F., 2006. Dry-cured ham. In: Hui, Y.H., Castell-Pérez, E., Cunha, L.M., et al. (Eds.), Handbook of Food Science, Technology and Engineering, vol. 4. Boca Raton, FL: CRC Press, pp. 164-1a−164-11a. Toldrá, F., 2011. Improving the sensory quality of cured and fermented meat products. In: Kerry, J.P., Kerry, J.F. (Eds.), Processed meats: improving safety, nutrition and quality. Cambridge: Woodhead Publishing, pp. 508–526. Toldrá, F., Aristoy, M.-C., 1995. Isolation of flavor peptides from raw pork meat and dry-cured ham. In: Charalambous, G. (Ed.), Food Flavors: Generation, Analysis and Process Influence. Amsterdam: Elsevier Science, pp. 1323–1344. Toldrá, F., Aristoy, M.C., 2010. Dry-cured ham. In: Toldrá, F. (Ed.), Handbook of Meat Processing. Ames, Iowa: Wiley-Blackwell, pp. 351–362. Toldrá, F., Flores, M., 1998. The role of muscle proteases and lipases in flavor development during the processing of dry-cured ham. CRC Critical Reviews in Food Science and Nutrition 38, 331–352.

Relevant Websites http://www1.clermont.inra.fr/tradisausage/ Agencia Estatal Consejo Superior de Investigaciones Científicas. http://www.iata.csic.es/IATA/dcie/carn/ Instituto de Agroquímica y Tecnología de Alimentos, Research Group: Science of Meat and Meat Products.

Natural and Organic Cured Meat Products in the United States JJ Sindelar, University of Wisconsin, Meat Science & Muscle Biology Laboratory, Madison, WI, USA r 2014 Elsevier Ltd. All rights reserved.

Glossary Alternative curing The technology of using natural sources of nitrate and/or nitrite from plants, vegetables, etc. to cure. Curing The addition of nitrite/nitrate with salt to a meat product to achieve improved preservation or the chemical entities of nitrite/nitrate. Nitrite A pale yellow, nearly white, crystalline compound that is highly soluble in water and highly reactive functioning as an oxidizing, reducing or nitrosating agent, and is converted to a variety of related compounds when added to meat.

Introduction Natural and organic processed meats have been a very significant part of the explosive market growth that has occurred in natural and organic foods. Producers and processors have responded to consumer demand for foods perceived by many to be more healthy and wholesome than conventionally produced food products by offering more and more products labeled as ‘natural’ or ‘organic.’ To qualify as natural or organic in the US, foods must be produced and processed in accordance with United States Department of Agriculture (USDA) regulations that define these products. These products are also produced in other countries around the world, though specific regulations differ somewhat. In most cases, natural and organic foods very closely resemble conventional products and do not differ in the typical characteristics expected by consumers. However, in the case of processed meat products such as hams, bacon, frankfurters, bologna, and others that are typically cured by addition of sodium nitrite, and sometimes sodium nitrate, the requirements for natural or organic marketing in the US do not permit addition of nitrite or nitrate and thus differences commonly exist. Therefore, a new category of ‘uncured’ processed meats often referred to as ‘alternatively cured’ products has been developed to provide consumers with the variety, convenience, and satisfaction of cured meat products while giving manufacturers the opportunity to meet consumer demand for natural and organic processed meat products.

Nitrosamines It is also known as N-nitroso compounds. A class of chemical compounds classified as carcinogenic that can be formed in cured meat, primarily bacon, under special conditions where secondary amines are present, nitrite is available, and necessary pH and high temperatures exist. Purified nitrite Nitrite that has been industrially produced by absorption of nitrogen oxides (NOx), originating from the catalytic air oxidation of anhydrous ammonia, into aqueous sodium carbonate or sodium hydroxide.

meat for centuries before researchers, in the late 1800s, discovered that nitrate was actually being converted into nitrite by nitrate-reducing bacteria, and that nitrite was the true curing agent. Nitrite is a highly reactive compound and it has become clear that the formation of nitric oxide (NO) from nitrite is a necessary prerequisite for many meat curing reactions. The addition of nitrite to cured meats fixes color, contributes to cured meat flavor, helps in the inhibition of the growth of microorganisms, specifically Clostridium botulinum, and effectively controls rancidity by inhibiting lipid oxidation. Sodium nitrite allows for the existence of meat and poultry products with unique colors, textures, and flavors that cannot be recreated by any other ingredient.

Regulations for the Conventional Curing Processes Current regulations restrict the use of nitrite and nitrate in the US and vary depending on the method of curing used and the product that is being cured (see Table 1). Bacon is an exception to the general limits for using curing agents because of the potential for nitrosamine formation and as a result has more stringent curing regulations. The curing accelerators permitted for use with nitrite are also restricted. Ascorbic and erythorbic acids, for example, cannot exceed 469 ppm (ppm) ingoing concentrations, while sodium ascorbate and erythorbate are limited to 547 ppm ingoing.

Alternative Curing – Systems and Labeling

Conventional Curing

Manufacturing Systems Conventional Cured Meat Ingredients Conventionally cured meat products are characterized and defined by the addition of nitrate and/or nitrite, which provide the distinctive properties that are common to all cured meat products. Saltpeter (potassium nitrate), first recognized as the original curing agent, was used in one form or another to cure

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Because the addition of purified nitrate and nitrite is prohibited for all ‘natural,’ ‘organic,’ or simply ‘uncured’ meat products to resemble traditionally cured meats, processors often utilize permitted natural ingredients and modified processing to achieve cured meat characteristics – a process that has become known as alternative curing.

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Curing | Natural and Organic Cured Meat Products in the United States Table 1

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Maximum allowable added levels for curing ingredients in meat and poultry in the United Statesa

Curing agent

Sodium Nitrite Potassium Nitrite Sodium Nitrate Potassium Nitrate

Curing method Immersion cured (ppm)

Massaged or pumped (ppm)

Comminuted (ppm)

Dry cured (ppm)

200 200 700 700

200 200 700 700

156 156 1718 1718

625 625 2187 2187

a

Limits are based on total formulation/brine weight for immersion cured, massaged, or pumped and raw meat (green) weight for comminuted or dry cured products.

The term ‘alternative curing’ is not officially recognized by the USDA, but refers to the original, ancient process that is the true origin of all modern cured meats. Alternative curing refers to the microbial conversion of naturally occurring nitrate, present in the environment, to nitrite, which then cures the meat in the same manner as if purified nitrite had been added. Because nitrate is an essential part of the total nitrogen cycle, naturally occurring nitrate can be present in the soil, sea water, various ‘sea salts,’ and green plants (including vegetables). Furthermore, many types of microorganisms in the environment have the ability to convert this naturally occurring nitrate into nitrite; thus, combining these two natural ingredients (vegetables or sea salt+harmless food-grade microorganisms) can result in a natural preservation system for meat. In general, natural curing processes now fall within one of the following three categories.

Culture system This process involves using a natural nitrate source material and a suitable meat culture. Both ingredients are added separately to the meat formulation and the nitrate conversion occurs in the meat during processing. Starter cultures containing a nitrate-reductase enzyme facilitate nitrate-to-nitrite conversion. The culture system used for alternative curing is driven by the culture concentration, and thus higher nitrite levels result from a greater percentage of culture used in the product formulation. The main advantage of the culture system is that some of the nitrite produced immediately reacts with the meat pigments to begin the curing process. The primary disadvantages are (1) the potential lengthening of the thermal process to allow adequate conversion and (2) the ‘lag period’ sometimes required to generate the nitrite can make some specific meat products and processes more vulnerable to the initial growth of undesirable microorganisms.

The advantage of this system is that nitrite produced in the brine can be measured and is available immediately for reaction when added to the meat, thus eliminating any ‘lag period.’ The main disadvantages are controlling the nitrate reduction in the liquid system and stabilizing the resulting nitrite produced to avoid nitrite loss before addition to the meat takes place.

Preconverted system This most recent and most commonly used system developed for alternative curing involves the intentional preconversion of nitrate to nitrite and stabilization of the nitrite produced, which is all done by the ingredient supplier. The resulting product in liquid or dry form originates from the same natural nitrate source, with the original nitrate mostly converted into nitrite. The preconverted product already contains the nitrite and is simply used by the meat processor as a curing agent, similar to conventional curing procedures. The main advantages of this system are the simplicity of adding a known quantity of nitrite and avoiding the use of viable microorganisms. The main disadvantages are, in general, (1) lower potential nitrite concentrations ultimately available for curing as opposed to using nitrate plus starter culture and (2) the handling of the preconverted product that is reactive (i.e., as with traditional nitrite cures).

Labeling Terms for Natural, Organic, and Uncured Processed Meats The labeling terms ‘natural,’ ‘organic,’ and ‘uncured’ refer to three distinct meat and poultry product categories governed by separate USDA labeling policies and federal regulations. By definition, none of the three types of products can have added nitrate and nitrite.

Prebrine system

Natural

This process also involves the use of both a natural nitrate source and a suitable meat starter culture; however, the nitrateto-nitrite reduction is accomplished by the meat processor, either partially or completely, in brine (liquid) before addition to the meat. The nitrate source and all, or a portion, of the meat culture, is first added to the brine, preferably without other ingredients. The nitrite is generated in solution by the microbial reduction of the added nitrate and is then subsequently added to the meat mix directly or via injection, after remaining ingredients have been added to the brine.

Processed meats that are labeled ‘natural’ must comply with the definition of the term provided by the USDA Food Standards and Labeling Policy Book. This definition requires that a natural product “does not contain any artificial flavor or flavoring, coloring ingredient, or chemical preservative (as defined in 21 CFR 101.22), or any other artificial or synthetic ingredient; and the product and its ingredients are not more than minimally processed.” The definitions for flavorings, coloring, and chemical preservatives can be found, as noted above, in Title 21 CFR, Chapter 1, Part 101, Subpart B

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(101.22)-subtitled Labeling of Spices, Flavorings, Colorings, or Chemical Preservatives. Furthermore, the term artificial color or coloring means any ‘color additive’ as found by definition in Title 21 CFR, Chapter 1, Part 70-Color Additives, Subpart A(f). The second relevant part of 21 CFR 101.22 is item number 5, which addresses chemical preservatives as follows: “The term chemical preservative means any chemical that, when added to food, tends to prevent or retard deterioration thereof, does not include common salt, sugars, vinegars, spices, oil extracted from spices, substances added to food by direct exposure thereof to wood smoke, or chemicals applied for their insecticidal or herbicidal properties….”

Organic Products labeled ‘organic’ are much better defined and controlled than those labeled with ‘natural’ claims because organic products are governed by the Organic Foods Production Act (OFPA), first passed in 1990 as part of the 1990 Farm Bill. The OFPA authorized the USDA to create a National Organic Standards Board, which established a National List of Allowed and Prohibited Substances and developed National Organic Program (NOP) standards. The NOP standards, implemented in 2002, specify methods, practices, and substances that are allowed for use for production, processing, and handling of organic foods. This means that products and ingredients used for organic foods must be certified as organic by a USDA-certified inspector. Meat, for example, must be raised using organic management and come from a certified farm. Ingredients used for processed products are clearly defined as permitted or prohibited in the OFPA National List.

Uncured The Code of Federal Regulations (9 CFR 317.17) states that normal cured products (“to which nitrate or nitrite is permitted or required to be added…”) can be made without nitrite or nitrate and labeled with such common or usual name or descriptive name when immediately preceded with the term ‘uncured.’ Additionally, specifically outlined, ‘No nitrate or nitrite added’ labeling is also required. All organic and natural products are uncured by definition, but not all uncured products are natural or organic.

General Labeling Regulations The labeling for uncured, natural, and organic meat products is very confusing and has yet to be totally resolved, particularly with regard to ‘alternative curing.’ All three product categories do not permit the use of added purified nitrite or nitrate salts; however, natural sources of these chemicals are permitted. The main issue is the separate USDA regulation that requires the labeling of a traditionally cured meat product as ‘uncured’ if purified nitrate and nitrite are not added. Specifically, “Any product, such as bacon and pepperoni, which is required to be labeled by a common or usual name or descriptive name in accordance with 9 CFR 317.2(c)(1) and to

which nitrate or nitrite is permitted or required to be added may be prepared without nitrate or nitrite and labeled with such common or usual name or descriptive name when immediately preceded with the term ‘Uncured’ as part of the product name, provided that the product is found by the Administrator to be similar in size, flavor, consistency, and general appearance to such product as commonly prepared with nitrate or nitrite, or both. In addition, these products must bear the statements ‘No Nitrate or Nitrite Added’ and ‘Not Preserved – Keep Refrigerated Below 40 °F at All Times’ unless they have been thermally processed to 3 1F or more, fermented or pickled to pH of 4.6 or less, or dried to a water activity of 0.92 or less.” Because these products are considered ‘uncured’ by the USDA, they must be processed accordingly. With the growth of alternative curing, the USDA now requires ‘uncured’ products to have a qualifying statement, ‘No Nitrates or Nitrites Added (except those occurring in sea salt and celery powder),’ if any of the ingredients may contain naturally occurring nitrate or nitrite. Only ‘traditionally cured’ products such as frankfurters, bacon, corned beef, pastrami, and pepperoni are required to follow the uncured labeling requirements for their natural, organic, and uncured alternatives. If the traditional product was not cured, such as oven roasted turkey breast, the natural alternative does not require uncured labeling. Additionally, some alternatively cured product alternatives are exempt from the ‘uncured’ labeling requirements altogether if they meet the outlined USDA criteria such as (1) achieving a water activity of 0.92 or less or (2) having a brine concentration of ≥10%.

Alternative Curing – Manufacturing Ingredients Alternative Curing Agents Natural nitrate sources Several natural nitrate sources are available for natural curing but the most common ingredients are based on celery juice or celery powder. This is a regularly available and consistent vegetable crop with relatively minimal negative sensory effects on meat product attributes such as flavor and color. Celery powder can also be labeled as ‘natural flavor’ according to USDA regulations and ‘celery powder’ is NOP approved for ‘organic meat products’ if 100% organic celery product with the same characteristics is not available. Celery juice is usually expressed as ‘celery juice’ on the label and is sold either in frozen or shelf-stable form depending on the concentration (brix) and pasteurization/packaging procedures. The main disadvantage of celery-based ingredients is that celery is considered an allergen or ‘sensitizing agent,’ and thus other vegetable ingredients suggested to be less allergenic than celery, such as Swiss chard, are being commercially developed. ‘Sea salt’ generally has not proved to be a consistent source of nitrate or nitrite and is no longer required for ‘natural’ labeling. With any natural nitrate or nitrite source ingredient, it is important to understand and have specifications for ‘nitrate’ (NO3−) and/or ‘nitrite’ (NO2−) ions, which are the active components. Often expressed as ‘sodium nitrate’ (NaNO3)

Curing | Natural and Organic Cured Meat Products in the United States and/or ‘sodium nitrite’ (NaNO2) as per the USDA regulations, the weight of the sodium salt is approximately 1.37x and 1.50x, respectively, of the nitrate or nitrite ions based on the atomic weight of each compound.

Natural preconverted nitrite sources Most of the preconverted natural ingredients containing nitrite are manufactured by using similar natural nitrate sources (e.g., celery) and similar meat cultures for the nitrate conversion. In general, preconverted juices or powders contain concentrations varying from 10 to 25 000 ppm (1–2%) expressed as sodium nitrite. The final concentrations are limited by the initial nitrate concentrations present in the various vegetable materials. These products are available in both liquid and dry form and provide a designated minimum nitrite ion, either designated as the ‘nitrite ion’ concentration or expressed as ‘sodium nitrite’ salt concentration. As with any natural product, these ‘preconverted’ vegetable products exhibit some color and flavor attributes that make the products somewhat ‘self-limiting’ in usage. However, improvements in both nitrite concentration and flavor control have allowed for addition levels that can now attain the maximum regulatory limits outlined for purified nitrite.

Nitrate-Reducing Starter Cultures Most meat cultures employed are harmless staphylococci strains that are also the most commonly used meat starter cultures worldwide. Originally, Staphylococcus carnosus was the most commonly used strain due to its nitrate reductase activity and previous successful use as a meat starter culture for color and flavor development. Because most existing S. carnosus strains were more active at relatively high temperatures (optimum at 90–100 F), the use of this starter culture in natural curing required elevated temperatures for the nitrate conversion, and thus the need for an ‘incubation period.’ Subsequently, other stains of staphylococci demonstrating higher nitrate reductase activity and functionality at lower temperatures were isolated and developed commercially. These ‘second-generation’ commercial meat cultures are a mixture of different S. carnosus strains (S. carnosus spp. utilis) and other staphylococci strains (i.e. Staphylococcus vitulinus). These culture blends are activated earlier in the process (at lower temperatures) and as a result are more efficient for nitrate conversion. The use of these blends results in overall higher nitrite generation and their use can minimize or even eliminate the need for an ‘incubation period.’

Natural Curing Adjuncts As with traditional curing, the addition of other natural compounds can enhance the natural curing process. Cherry powder and acerola juice and powder are products containing relatively high levels of natural occurring ascorbic acid, which is an oxygen scavenger (reductant) and metal ion sequestrant that serves as a curing accelerator. Citrus powders (e.g., lemon, lime) also contain naturally occurring ascorbic acid as well as citric acid, which are also effective as natural curing accelerators and antioxidant synergists.

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Other Natural Ingredients Antioxidants A number of natural compounds with antioxidant activity exist. Rosemary and other herb extracts, as well as extracts of green tea and grape seed, serve as natural free radical scavengers inhibiting fat, protein, and meat pigment oxidation when incorporated into natural meat and poultry products.

Preservatives Citrus juices and powders used as curing adjuncts are typically used at relatively low concentrations; however, when used at higher levels, they can serve a dual function as microbial inhibitors, particularly in combination with vinegar. Acetic acid, di-acetate, and acetates are proven antimicrobial ingredients and are available ‘naturally’ in the form of vinegar, specifically if the vinegar is considered ‘minimally processed.’ Technically, sodium lactates are not USDA approved for ‘natural’ labeling unless it can be shown that they are being used as ‘flavoring agents’ to extend shelf life and not as ‘chemical preservatives’ to extend shelf life. Generally, the acceptable level is less than 2%.

Binding and texturizing agents Natural meat products commonly exhibit lower yields with looser texture and lower product pH because ingredients such as sodium phosphates are not allowed. For natural meat products some water-binding agents are approved if considered ‘minimally processed.’ Carageenan (seaweed) is the most commonly used, with some gums such as xanthan gum also being utilized. Raising the brine and/or product pH with added sodium bicarbonate or sodium carbonate can also achieve increased yields.

Flavorings ‘Natural flavoring’ has generally been defined by the USDA as the essential oil, oleoresin essence, or extractive, protein hydrolysate, distillate, or any product of roasting, heating, or enzymolysis that contains the flavoring constituents derived from natural sources such as spices, fruits, vegetables, plants, meats, and seafood. Celery, onion, and garlic powders are considered foods rather than spices and thus can be labeled as natural flavorings, while the respective juice derivatives must be labeled as ‘juice,’ for example, ‘celery juice,’ etc. (9 CFR, Part 318). Generally, if the flavoring is derived from natural sources and is considered minimally processed, it can be used in natural meat products. Often, the actual material from which the flavoring is derived must be either labeled or approved. In addition, ‘spice oleoresins’ are specifically mentioned as acceptable in natural meat products by the USDA.

Alternative Curing – Manufacturing Procedures General Manufacturing Procedures Aside from the replacement of normal curing ingredients, such as sodium nitrate and nitrite with natural curing ingredients, and the addition of an incubation step to allow for nitrate-tonitrite reactions to occur (if a system with starter culture is

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used), all other processing procedures can generally remain unchanged. Two steps in the process are, however, considered critical for the successful manufacture of alternatively cured products. The first critical step is the level of ingoing nitrate/nitritecontaining source added. The highest amount possible should be added but care must be taken as levels that are too high can negatively affect finished product aroma or flavor. Ideally, the natural nitrate/nitrite-containing ingredient should be added at a level slightly lower than the amount that induces ingredient-related (e.g., vegetable-like) aromas and flavors in the finished product. This approach is preferred over following ‘minimum recommended levels’ suggested by manufacturers so that the greatest extent of curing can take place. The product itself, however, must also be taken into consideration because those products that are more heavily spiced (frankfurters, polish sausage, etc.) tend to allow for higher levels of nitrate/ nitrite-containing ingredients before changes in aromas and flavors are detected. The second critical step for successful alternative curing is incubation (if the culture system is used). The incubation step is where nitrate-to-nitrite conversion occurs and is commonly performed at the very beginning of thermal processing. However, in the case of multi-strain cultures, much of the necessary nitrate-to-nitrite conversion can potentially take place during product manufacture and before thermal processing. Thus, a thermal processing incubation step may be substantially shortened. Regardless of starter cultures used and their associated functional temperature properties, the amount of nitrite converted from nitrate during incubation is a function of both temperature and time. Incubation temperatures corresponding to the optimal activity of the specific starter culture are used in concert with an incubation time that provides enough time to allow for a high percentage of the nitrate to be converted to nitrite. As such, incubation is an extremely critical manufacturing step and proper control of this step can significantly impact the quality, shelf life quality, and safety of the finished product. A minimum of 2 h of incubation time, where product is held at optimal incubation temperature, is recommended.

Comminuted Sausage Manufacture If ingredients that have been preconverted to nitrite are used for comminuted sausage, they may be directly added during the addition of other nonmeat ingredients. If a culture system is used, it is first advised to mix the culture in a portion of the formulation water to allow for better distribution when added to the meat mixture. In addition, because the starter cultures will go into suspension but will not go into solution when mixed with water, proper periodic agitation to maintain suspension is also important.

the brine or solution with no additional processing changes needed. Thus, no changes in manufacturing practices are needed with the inclusion of preconverted ingredients. However, if a culture system is used, then special attention must be taken to ensure successful alternative curing. Because the starter culture is not water soluble, it must be injected or physically placed inside the meat so that it can come in contact and interact with the nitrate-containing ingredient. Tumbling or immersion methods would be ineffective, resulting in natural curing failure (e.g. uncured spots) because the starter culture would not be carried to the muscle interior by the tumbling or immersion curing process. As an example, a product in which tumbling is traditionally used as the means of incorporating a brine or solution must instead be injected. However, because vegetable juices/powders are water soluble, they could be carried to the muscle interior through tumbling or immersion practices.

‘Alternatively Cured’ Meat Product Challenges Quality Implications Lipid oxidation and cured meat color are the two qualityrelated challenges most often associated with alternative curing. Because lower levels of nitrite typically exist in alternatively cured products, the amount of unsaturated lipids in a product, the rate and extent of oxidation of those lipids at the time of processing, the length and type (frozen or refrigerated; aerobic or anaerobic packaging) of product storage, and the actual amount of nitrite generated during processing can have substantial effects on the oxidative stability of the lipids. Cured color and the shelf life of that color are greatly impacted by good curing practices. Because little nitrite (o20 ppm) is necessary to induce a cured color and much more is needed to maintain that cured color throughout the stored shelf life (∼450–60 ppm), a false sense of product quality could result if inadequate alternative curing occurred because acceptable cured color could be present immediately after product manufacture but then rapidly fade within weeks, days, or even hours. To prevent this from occurring, maximizing the amount of nitrite generated will result in a more desirable amount of residual nitrite that can later be used for cured color regeneration during product shelf life. The microbiological quality properties of alternative and organic meat products are also affected by alternative curing. As the level of nitrite and use of ingredients with antimicrobial properties decreases, nonpathogenic spoilage bacteria have greater ability to grow and can reduce product shelf life. Anaerobic packaging and temperature control can be used to help address microbiological quality changes and limit product quality deterioration.

Safety Implications Whole Muscle Product Manufacture Whole muscle product manufacture includes any product in which the incorporation of curing and/or other ingredients is accomplished by injection, tumbling, or immersion. If a preconverted system is used, ingredients may be directly added to

The safety of alternatively cured processed meats is a significant concern because nitrite is a very well-known and effective antimicrobial agent, particularly for preventing toxin production by C. botulinum. The issue for processed meats that use natural sources of nitrate in a culture system is that the

Curing | Natural and Organic Cured Meat Products in the United States true amount of nitrite formed is unknown and impossible to measure because nitrite reacts quickly with meat components. Although the amount of detectable residual nitrite in these products is significant, it is typically less than that found in traditional, nitrite-cured products. Consequently, the microbial safety of processed meats manufactured with natural sources of nitrate is very difficult to assess without microbiological challenge studies. However, several studies have shown that the inclusion of ingredients possessing antimicrobial properties can significantly enhance the safety of the products. The preconverted system is not presented these same challenges, however care in ensuring adequate levels of nitrite are used to attain equivalent quality and safety results as with purified nitrite is important.

See also: Additives: Extenders; Functional. Curing: Brine Curing of Meat; Production Procedures. Microbiological Safety of Meat: Clostridium botulinum and Botulism; Clostridium perfringens; Salmonella spp.

Further Reading Sebranek, J.G., Bacus, J.N., 2007. Cured meat products without direct addition of nitrate or nitrite: What are the issues? Meat Science 77, 136–147. Sindelar, J.J., Cordray, J.C., Sebranek, J.G., Love, J.A., Ahn, D.U., 2007a. Effects of vegetable juice powder concentration and storage time on some chemical and

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sensory quality attributes of uncured, emulsified, cooked sausages. Journal of Food Science 72, S324–S332. Sindelar, J.J., Cordray, J.C., Sebranek, J.G., Love, J.A., Ahn, D.U., 2007b. Effects of varying levels of vegetable juice powder and incubation time on color, residual nitrate and nitrite, pigment, pH and sensory attributes of ready-to-eat uncured ham. Journal of Food Science 72, S388–S395. Terns, M.J., Milkowski, A.L., Claus, J.R., Sindelar, J.J., 2011. Investigating the effect of incubation time and starter culture addition level on quality attributes of indirectly cured, emulsified cooked sausages. Meat Science 88, 454–461. Terns, M.J., Milkowski, A.L., Rankin, S.A., Sindelar, J.J., 2011. Determining the impact of varying levels of cherry powder and starter culture on quality and sensory attributes of indirectly cured, emulsified cooked sausages. Meat Science 88, 311–318. USDA, 2005. Food Standards and Labeling Policy Book. United States Department of Agriculture-Food Safety Inspection Service. Available at: www.fsis.usda.gov/ OPPDE/larc/Policies/Labeling_Policy_Book_082005.pdf (accessed 21.12.09). Winter, C.K., Davis, S.F., 2006. Organic foods. Journal of Food Science 71, R117–R124. Xi, Y., Sullivan, G.A., Jackson, A.L., Zhou, G.H., Sebranek, J.G., 2012. Effects of natural antimicrobials on inhibition of Listeria monocytogenes and on chemical, physical and sensory attributes of naturally-cured frankfurters. Meat Science 90, 130–138.

Relevant Websites http://amif.org/ht/a/GetDocumentAction/i/62610 American Meat Institute Foundation. http://www.meatscience.org/page.aspx?id=403 American Meat Science Association.

Physiology of Nitric Oxide D Parthasarathy and NS Bryan, Texas Therapeutics Institute, Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center at Houston, Houston, USA r 2014 Elsevier Ltd. All rights reserved.

Introduction Salting as a means of preserving meat, poultry, fish, seafood, and vegetables predates written history and was essential in ancient times for providing nutrient-dense foods during scarcity or population migration and before refrigeration was an option. Meat curing is historically defined as the addition of salt to fresh meat cuts to remove moisture and reduce the water activity of the tissues to prevent spoilage. However, salt is poorly defined as there are many salts that can fulfill this activity although some are better than others. In ancient times, salt was obtained from crystalline deposits left by evaporating water from brine pools, seawater, or mining directly from the earth. As a consequence, it often contained natural contaminants such as sodium or potassium nitrate or nitrite that contributed directly to the curing reaction and the preservation process, although unrecognized at the time. These contaminants, nitrite and nitrate, as it was later learned, were the primary components in curing reactions. The reduction of nitrate (NO3−) salts to nitrite (NO2−) and then to gaseous NO and its subsequent reaction with myoglobin to form the nitrosyl–myoglobin complex forms the basis for cured meat flavor and color. It was also later realized that it is bacteria that first converts nitrate into nitrite, which is the mechanism underlying in the preservation of food. Nitrite in meat is responsible for inhibiting the growth of aerobic and anaerobic bacteria (especially the spores from Clostridium botulinum), retarding the development of rancidity during storage, developing and preserving the meat flavor and color, stabilizing the oxidative state of lipids in meat products. At present most cured meats contain added sodium nitrite or cultured celery extract where the naturally contained nitrate is reduced to nitrite by a starter culture of bacteria. For many years, some epidemiological data have implicated that nitrite and nitrate in cured and processed meats are responsible for a number of human diseases including some cancers. Although modestly increased associations between consumption of foods containing nitrite and nitrate and certain cancers have been reported in some prospective epidemiological studies overall, findings across studies have been largely inconsistent and equivocal. Consequently, the overall burden of proof remains inconclusive. A biologically plausible mechanism for the carcinogenicity of ingested nitrate and nitrite involves endogenous N-nitrosation reactions. Although generally considered harmful due to the formation of N-nitrosamines, biomedical science over the past 20 years has recognized the nitrosation reaction as an essential fundamental process in mediated cell signaling. Despite this new emerging science on NO, nitrite, and nitrate, there are still very strict regulations of nitrate and nitrite levels in our food and drinking water. In the early 1980s it was shown that, in addition to dietary exposure, nitrate and nitrite are also generated endogenously. Shortly thereafter, the entire L-arginine–nitric oxide synthase

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(NOS)-system was discovered and was found to be the major endogenous source of nitrate and nitrite, because NO is rapidly oxidized to these higher nitrogen oxides. Until recently, biologists considered nitrate and nitrite merely as inactive endproducts of NO metabolism, but this view is rapidly changing. It is now clear that nitrite and nitrate can recycle in vivo and again form bioactive nitrogen oxides, including NO. Interestingly, commensal bacteria in the human oral cavity play a key role in the bioactivation of nitrate. A picture is emerging suggesting physiological, nutritional, as well as therapeutic roles for the nitrate–nitrite–NO pathway. Thus, instead of simply wasting the products of NO oxidation, mammals store and actively recycle it. Nitrite reduction to NO was first described in the stomach, where salivary nitrite forms NO nonenzymatically via acid-catalyzed reduction. Soon after this observation, researchers described NOS-independent nitrite reduction in the ischemic and acidic heart. In the past 10 years it has become evident that blood and tissue nitrite are reduced under physiological conditions to form NO and modulate blood flow. Subsequent studies show that a variety of enzymes and proteins can catalyze the one-electron reduction of nitrite to NO in blood and tissues. The authors will review the nitrate–nitrite–nitric oxide pathway in human physiology and highlight this fundamental pathway, which has been recently shown to afford enormous health benefits to humans. The picture that has emerged is that foods that contain nitrite and nitrate confer profound health benefits representing a complete change in paradigm requiring reconsideration of the riskbenefit analysis on nitrite and nitrate.

Nitric Oxide Biochemistry and Physiology Before the nitrate–nitrite–NO pathway is reviewed, it is first necessary to describe the fundamental roles and production pathways for NO and its implications in health and disease to better appreciate the new-found role of nitrite and nitrate. The discovery of the mammalian biosynthesis of NO and its roles in the immune, cardiovascular, and nervous systems in the 1980s established a startling new paradigm in the history of cellular signaling mechanisms. Before that discovery, it was essentially inconceivable that cells would intentionally produce a toxic molecule as a messenger; NO was previously known as a common air pollutant, a constituent of cigarette smoke, and a toxic gas, which appears in the exhaust of automobiles and jet airplanes, causes acid rain, and destroys the ozone layer. Amazingly, despite this nasty reputation, it is now known that NO is one of a family of reactive signaling molecules, which includes both reactive nitrogen and reactive oxygen species that perform essential cellular functions in the body. This is, in fact, a hallmark example of the propensity of nature to seek out and exquisitely utilize the unique properties of unusual molecules. This same theme is emerging around

Encyclopedia of Meat Sciences, Volume 1

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Curing | Physiology of Nitric Oxide nitrite. Once considered an unwanted, toxic food additive and now considered an essential nutrient, much of the chemistry that was described centuries ago is now reemerging in human physiology. NO is one of the most important signaling molecules in the body, and is involved in virtually every organ system where it is responsible for modulating an astonishing variety of effects. NO has been shown to be involved in and affect (just to list a few major examples) neurotransmission, memory, stroke, glaucoma, and neural degeneration such as in Alzheimer′s disease, pulmonary hypertension, penile erection, angiogenesis, wound healing, atherogenesis, inflammation such as arthritis, nephritis, colitis, autoimmune diseases (diabetes, inflammatory bowel disease), invading pathogens, tumors, asthma, tissue transplantation, septic shock, platelet aggregation and blood coagulation, sickle cell disease, gastrointestinal motility, hormone secretion, gene regulation, hemoglobin delivery of oxygen, stem cell proliferation and differentiation, and bronchodilation. One can then imagine the host of diseases or conditions that may be caused or affected by the body′s dysregulation of NO production/ signaling. Maintaining NO homeostasis is critical for optimal health and disease prevention, and understanding foods and diets that promote NO activity will have a profound effect on public health. The discovery of the NO pathway represented a critical advance in the understanding of cell signaling and subsequently into major new advancements in many clinical areas including, but not limited to, cardiovascular medicine. This seminal finding was viewed as so fundamentally important that the Nobel Prize in Physiology or Medicine was awarded to its discoverers, Drs. Louis J. Ignarro, Robert Furchgott, and Ferid Murad in 1998, a short 11 years after NO was identified. Dr. Valentin Fuster, then president of the American Heart Association, noted in a 1998 interview that “the discovery of NO and its function is one of the most important in the history of cardiovascular medicine.” In fact, development of NO-based drugs and therapies is a major priority for big pharmaceutical companies. Drugs like Viagra and Cialis for erectile dysfunction are effective because they affect the NO pathway, which allows for blood vessel relaxation and blood flow into the corpus cavernosum for penile erection. Enhancing this effect through dietary means may provide a safer and more natural alternative. What is clear is that continuous generation of NO is essential for the integrity of the cardiovascular system, and decreased production and/or bioavailability of NO is central to the development of many disorders. The production of NO from L-arginine is a complex and complicated biochemical process involving a 5-electron oxidation with many cofactors and prosthetic groups carried out by a group of enzymes called nitric oxide synthase (NOS). There are three isoforms of NOS, neuronal NOS (nNOS or NOS 1), inducible NOS (iNOS or NOS 2), and endothelial NOS (eNOS or NOS 3). It is the NO produced by iNOS that is responsible for killing of bacteria. There are many steps or factors that may be altered and may affect ultimate NO production. Once produced, NO can be quickly scavenged before it has a chance to perform its actions. It is, therefore, a war of attrition when it comes to producing bioactive NO, and is a remarkable feat that this short-lived gas is responsible for so many essential cellular activities.

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Understanding strategies to restore NO homeostasis will represent a major breakthrough in disease management and prevention.

Nitrite and Nitrate in Human Physiology Although the L-arginine–NO pathway was the first to be discovered, it does not necessarily mean that it is the primary pathway for the endogenous production of NO. In fact, nitrogen cycling in bacteria and production of NO as an intermediate in denitrification may be one of the most primitive pathways known, dating back to the Archean era. The now recognized human nitrate–nitrite–nitric oxide pathway that still relies on bacteria may be a redundant system for overcoming the body′s inability to make NO from L-arginine. It appears that we have at least two systems for affecting NO production/homeostasis. The first is through the classical L-arginine–NO pathway. This is a complex and complicated five-electron oxidation of L-arginine and if any of the cofactors become limiting, then NO production from NOS shuts down, and in many cases, NOS then produces superoxide instead. The enzymatic production of NO normally proceeds very efficiently. However, in disease characterized by oxidative stress where essential NOS cofactors become oxidized, NOS uncoupling, or conditions of hypoxia where oxygen is limiting, this process can no longer maintain NO production. Therefore, one can argue saliently that there has to be an alternate route for NO production. It is highly unlikely that nature devised such a sophisticated mechanism of NO production as a sole source of a critical molecule. This alternate route involves the provision of nitrate and nitrite reductively recycled to NO. Inorganic nitrite and nitrate are still considered at present in the media and public predominantly as undesired residues in the food chain or as inert oxidative end-products of endogenous NO metabolism. However, from research performed over the past decade, it is now apparent that nitrate and nitrite are physiologically recycled in blood and tissues to form NO and other bioactive nitrogen oxides. Nitrite is an oxidative breakdown product of NO that has been shown to serve as an acute marker of NO flux/formation. Nitrite is in steady state equilibrium with S-nitrosothiols and has been shown to activate soluble guanylyl cyclase (sGC) and increase the second messenger cGMP levels in tissues, activities very similar to NO.

Sources and Estimates of Exposure to Nitrite and Nitrate The health concerns for exposure to nitrite and nitrate have been focused on the levels of nitrite and nitrate in the diet and primarily their content in cured meats. As with any compound, dose dictates poison and at high concentrations, pure nitrite can be toxic. The reported LD50 on a material safety data sheet (MSDS) is 175–180 mg kg−1 in rodents. The lowest acute oral lethal dose of nitrite has been reported to vary from 33– 250 mg kg−1 body weight, which might be applied to children or the elderly. Estimates of the lethal dose of potassium nitrate (KNO3−) have ranged from 4 to 30 g. A realistic estimate of a

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lethal dose in adults is 20 g nitrate ion or 330 mg nitrate ion per kilogram body weight. The National Academy of Sciences in 1981 concluded that 39%, 34%, and 16% of the dietary intake of nitrite were derived from cured meat, baked goods/ cereal, and vegetables, respectively. More recent reports have shown that less than 5% of the total ingested nitrite and nitrate are derived from cured meat sources with the remainder coming from vegetables and saliva. In an assessment of nitrate, nitrite, and N-nitroso compounds in the human diet, it was concluded that vegetables contribute more than 85% of the daily dietary intake of nitrate and that endogenous synthesis is an important contributor to humans′ overall exposure to nitrate. The National Research Council has estimated, based on food consumption tables, that the average total nitrite and nitrate intake in the USA was 0.77 and 76 mg, respectively. However, more sensitive and accurate analytical methods and changes in agricultural practices over the past few decades may have changed our consumption values. International estimates of nitrate intakes from food are 31–185 mg per day in Europe and in the USA approximately 40–100 mg per day. A healthy 70 kg person produces 1.68 mmol NO per day (based on 1 µmol (kg h)−1 NO production). Using the conservative estimates of an average daily intake of 0.77 mg of nitrite would equate to 11.1 µmol per day and 76 mg nitrate would equate to 894 µmol per day or approximately 1 mmol of nitrite and nitrate per day from diet. This almost matches what our body makes from NO if we assume most of the NO goes to stepwise oxidation to nitrite and nitrate. Therefore our steady state levels of NOx, which are routinely used as clinical biomarkers of NO activity come almost 50% from diet. In fact, it has been suggested that people consuming certain diets, such as the dietary approaches to stop hypertension (DASH) diet get more than 1000 mg of nitrate. Nitrate is also used on toothpaste formulations in the form of potassium nitrate, designed for sensitive teeth (approximately 5000 ppm) representing a major source of exposure.

Human Nitrogen Cycle: Reductive Pathways to Produce NO from Nitrite and Nitrate The bioactivation of nitrate from dietary or endogenous sources requires its initial reduction to nitrite, and because mammals lack specific and effective nitrate reductase enzymes, this conversion is mainly carried out by commensal bacteria in the mouth and gastrointestinal tract and on body surfaces. Nitrate from the diet is rapidly absorbed in the upper gastrointestinal tract. In the blood, it mixes with the nitrate formed from the oxidation of endogenous NO produced from the NOS enzymes. After a meal rich in nitrate, the levels in plasma increase greatly and remain high for a prolonged period of time (plasma half-life of nitrate is 5–6 h). The nitrite levels in plasma also increase after nitrate ingestion. Although much of the nitrate is eventually excreted in the urine, up to 25% is actively taken up by the salivary glands and is concentrated up to 20-fold in saliva. Once in the mouth, commensal facultative anaerobic bacteria reduce nitrate to nitrite during respiration by the action of nitrate reductases. Human nitrate reduction requires the presence of these bacteria – suggesting a functional symbiosis relationship – as mammalian cells cannot

effectively metabolize this anion. The salivary nitrate levels can approach 10 mM and nitrite levels 1–2 mM after a dietary nitrate load. When saliva enters the acidic stomach (1–1.5 L per day), much of the nitrite is rapidly protonated to form nitrous acid (HNO2; pKa ∼3.3), which decomposes further to form NO and other nitrogen oxides. Nitrite excreted in saliva has significant antibacterial properties. Nitrite also contributes to the bactericidal effects of gastric fluids as demonstrated by some studies on the food-borne pathogens like Escherichia coli. Nitrite and nitric oxide are also shown to have antibacterial benefits against Helicobacter pylori, certain strains of bacteria responsible for dental caries and skin pathogens. This human nitrogen cycle is illustrated in Figure 1. Once nitrite is absorbed and circulated, it is taken up by peripheral tissues and can be stored in cells. The one-electron nitrite reduction to NO can occur in a much simpler mechanism than the two-electron reduction of nitrate by bacteria. The one-electron reduction of nitrite can occur by ferrous heme proteins (or any redox active metal) through the following reaction: NO2−+Fe(II)+H+↔NO+Fe(III)+OH− This is the same biologically active NO as that produced by NOS, with nitrite rather than L-arginine as the precursor, and is a relatively inefficient process. Much of the recent focus on nitrite physiology is due to its ability to be reduced to NO during ischemic or hypoxic events. Nitrite reductase activity in mammalian tissues has been linked to the mitochondrial electron transport system, protonation, deoxyhemoglobin, and xanthine oxidase. Nitrite can also transiently form nitrosothiols (RSNOs) under both normoxic and hypoxic conditions, and a recent research demonstrated that steady state concentrations of tissue nitrite and nitroso are affected by changes in dietary NOx (nitrite and nitrate) intake. Furthermore, enriching dietary intake of nitrite and nitrate translates into significantly less injury from heart attack. Previous studies also demonstrated that nitrite therapy given intravenously before reperfusion (restoration of blood flow) protects against hepatic and myocardial ischemia/reperfusion (I/R) injury. Additionally, experiments in primates revealed a beneficial effect of long-term application of nitrite on cerebral vasospasm. Moreover, inhalation of nitrite selectively dilates the pulmonary circulation under hypoxic conditions in vivo in sheep. Topical application of nitrite improves skin infections and ulcerations. Furthermore, in the stomach, nitrite-derived NO seems to play an important role in host defense and in regulation of gastric mucosal integrity. All these studies together along with the observation that nitrite can act as a marker of NOS activity (reflective of total body NO availability) opened a new avenue for the diagnostic and therapeutic application of nitrite, especially in cardiovascular diseases, using nitrite as a marker as well as an active agent. Oral nitrite has also been shown to reverse NG-nitro-Larginine methyl ester (L-NAME – a NOS inhibitor) induced hypertension and serve as an alternate source of NO in vivo. In fact, a recent research report demonstrated that plasma nitrite levels progressively decrease with increasing cardiovascular risk. Because a substantial portion of steady state nitrite concentrations in blood and tissue are derived from dietary

Figure 1 Human nitrogen cycle.

Low gastric pH reduces nitrite to NO

Bacteria on tongue surface Commensal bacteria reduce 20% of nitrate to nitrite Tongue

Dietary nitrate and nitrite intake

Nitrate and nitrite absorbed by intestines

Salivary glands

25% Circulating nitrate concentrated in salivary glands

Systemic circulation – nitrite and nitrate delivered throughout the body

Majority of nitrate filtered and reabsorbed

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sources, modulation of nitrite and/or nitrate intake may provide a first line of defense for conditions associated with NO insufficiency. In fact it has been reported that dietary nitrate reduces blood pressure in healthy volunteers.

health perspective, better recommendations can be made on diet and dramatically affect the incidence and severity of cardiovascular disease and the subsequent clinical events. Replenishing nitrate and nitrite through dietary means may then act as a protective measure to compensate for insufficient NOS activity under conditions of hypoxia or in a number of conditions characterized by NO insufficiency. In fact, use of a rationally designed nitrite- and nitrate-enriched dietary supplement has been shown in a clinical trial to restore NO homeostasis and modify cardiovascular risk factors such as hyperlipidemia. One cannot help but notice the emerging physiological data on nitrite are strikingly analogous to a vitamin. Vitamine or vital amine was the term coined by Casimir Funk (1884– 1967) for the unidentified substances present in food, which could prevent the diseases scurvy, beriberi, and pellagra. A vitamin is by definition any of a group of organic substances essential in small quantities to normal metabolism, found in minute amounts in natural foods or sometimes produced synthetically: deficiencies of vitamins produce specific disorders. We may have identified a new vitamin, perhaps vitamin N. We know that nitrite is produced in relatively small quantities in normal metabolism of L-arginine and reduction of nitrate and is found in minute amounts in natural foods. Many animal studies reveal that nitrite insufficiency exacerbates I/R injury and increases mortality from I/R. There are a host of diseases that are associated with decreased NO availability as measured by nitrite. Becoming more evident is the

Conclusion The emerging health benefits of nitrite and nitrate represent a profound change in paradigm from the past 50 years. Until now, scientists have operated under the paradigm of the L-arginine–NO pathway by NOS enzymes as the only pathway to produce NO. As shown in Figure 2, there are a number of recycling pathways to regenerate NO from dietary nitrite and nitrate. The emergence of a redundant pathway for maintenance of NO homeostasis by dietary nitrite and nitrate provides a new mode of intervention and a new paradigm for restoring NO homeostasis. The provision of nitrate and nitrite as sources of NO may then be viewed as a system of redundancy. Therefore, industry efforts to reduce nitrite and nitrate in the curing process may not be meaningful. In fact, nitrite and nitrate therapy or supplementation may restore NO homeostasis from endothelial dysfunction and provide benefit in a number of diseases characterized by NO insufficiency. If so, this will provide the basis for new preventive or therapeutic strategies and new dietary guidelines for optimal health. There are currently a number of clinical trials using sodium nitrite as a therapeutic agent (www.clinicaltrials.gov). From a public

Oxyhemoglobin in blood

Oxyhemoglobin in blood

Nitrate

Ceruloplasmin

Dissolved oxygen in blood/tissues

Nitrite

Deoxyhemoglobin in blood

Nitric oxide

Deoxymyoglobin in muscles Xanthine oxidase in tissues

Cytochromes in liver/tissues

Protons

Nitrous acid

Figure 2 Different pathways of nitrite, nitrate, and NO in human body.

Bacterial nitrate reductase (in the oral cavity)

Nitrite

Xanthine oxidase (in the tissues)

NADPH, FAD, FMM

Nitric oxide synthase

BH4, GSH, O2, Ca/CM

L-Arginine

Curing | Physiology of Nitric Oxide enormous benefit of exogenous dietary nitrite and nitrate in a number of disease models in animals and even in humans. Very little can affect our health more than what we choose to eat and our daily lifestyle habits. The realization of a nitrate– nitrite–nitric oxide pathway suggests that NO can be modulated by the diet independent of its enzymatic synthesis from L-arginine, for example, the consumption of nitrite- and nitrate-rich foods, such as leafy vegetables or meats to which nitrite is added. Diet and nutrition may be the key to NOrelated therapies. After all it was Hippocrates who said, “Let food be thy medicine and medicine be thy food.” The active agent of some medicinal foods may very well be nitrite.

See also: Additives: Functional. Chemical Analysis for Specific Components: Curing Agents. Chemical and Physical Characteristics of Meat: Color and Pigment. Curing: Brine Curing of Meat; Natural and Organic Cured Meat Products in the United States

Further Reading Bryan, N.S., 2006. Nitrite in NO biology: cause or consequence? A systems-based review. Free Radical Biology & Medicine 41 (5), 691–701. Bryan, N.S., 2009a. Cardioprotective actions of nitrite therapy and dietary considerations. Frontiers in Bioscience 14, 4793–4808. Bryan, N.S. (Ed.), 2009b. Food, Nutrition and the Nitric Oxide Pathway. Pennsylvania: DesTech Publishing. ISBN: 978-1-932078-84-8. Bryan, N.S., Calvert, J.W., Elrod, J.W., et al., 2007. Dietary nitrite supplementation protects against myocardial ischemia−reperfusion injury. Proceedings of the National Academy of Sciences of the USA 104 (48), 19144–19149.

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Bryan, N.S., Fernandez, B.O., Garcia-Saura, M.F., et al., 2005. Nitrite is a signaling molecule and regulator of gene expression in mammalian tissues. Nature Chemical Biology 1, 290–297. Bryan, N.S., Loscalzo, J. (Eds.), 2011. Nitrite and Nitrate in Human Health and Disease. New York: Springer Humana Press. ISBN: 978-1-60761-615-3. Bryan, N.S., Zand, J., Gottlieb, B., 2010. The Nitric Oxide (NO) Solution. Good for you Books Publishing. ISBN: 978-0-615−41713-4. Butler, A.R., Feelisch, M., 2008. Therapeutic uses of inorganic nitrite and nitrate: from the past to the future. Circulation 117 (16), 2151–2159. Elrod, J.W., Calvert, J.W., Gundewar, S., Bryan, N.S., Lefer, D.J., 2008. Nitric oxide promotes distant organ protection: evidence for an endocrine role of nitric oxide. Proceedings of the National Academy of Sciences of the United States of America 105 (32), 11430–11435. Hord, N.G., Tang, Y., Bryan, N.S., 2009. Food sources of nitrates and nitrites: The physiological context for potential health benefits. American Journal of Clinical Nutrition 90 (1), 1–10. Kevil, C.G., Kolluru, G.K., Pattillo, C.B., Giordano, T., 2011. Inorganic nitrite therapy: historical perspective and future directions. Free Radical Biology & Medicine 51 (3), 576–593. Lundberg, J.O., Gladwin, M.T., Ahluwalia, A., et al., 2009. Nitrate and nitrite in biology, nutrition and therapeutics. Nature Chemical Biology 5 (12), 865–869. Lundberg, J.O., Weitzberg, E., Gladwin, M.T., 2008. The nitrate−nitrite−nitric oxide pathway in physiology and therapeutics. Nature Reviews Drug Discovery 7 (2), 156–167. Milkowski, A., Garg, H.K., Coughlin, J.R., Bryan, N.S., 2010. Nutritional epidemiology in the context of nitric oxide biology: A risk-benefit evaluation for dietary nitrite and nitrate. Nitric Oxide 22 (2), 110–119. Zand, J., Lanza, F., Garg, H.K., Bryan, N.S., 2011. All-natural nitrite and nitrate containing dietary supplement promotes nitric oxide production and reduces triglycerides in humans. Nutrition Research 31 (4), 262–269.

Relevant Website http://www.uthouston.edu/imm/centers/texas-therapeutics-institute.htm University of Texas.

Production Procedures RB Pegg, University of Georgia, Athens, GA, USA JA Boles, University, Animal Bioscience Building, Bozeman, MT, USA r 2014 Elsevier Ltd. All rights reserved. This article is a revision of the previous edition article by RB Pegg, volume 1, pp 349–360, © 2004, Elsevier Ltd.

Glossary Brine A solution of salt (usually sodium chloride) in water. For meat curing, cure ingredients (sodium nitrite) are added to the salt solution to create a brine to affect a cure in meat. Corned (beef) Granulated or grain salt was formerly called ‘corn,’ from old Old Norse, ‘korn,’ meaning grain. Cure To preserve meat, as by salting with nitrates and/or nitrites, smoking, or aging. Dry curing Salt containing nitrates and nitrites are rubbed by hand onto the surface of a meat cut or ham. The pork pieces are packed and left for a few weeks. The product is often overhauled during this period. N-nitrosamines Potential reaction products generated from nitrites and secondary amines of meat, most of which are carcinogenic. High temperatures, as in the frying of bacon, can enhance the formation of N-nitrosamines. Prague powder 1 (Cure 1) A mixture of 1 oz of sodium nitrite (6.25%) to 1 lb of salt. Both Cure 1 and 2 contain a small amount of FDA-approved red coloring agent, which gives them a slight pink color thus eliminating any possible

Introduction The origin of salting meats is lost in antiquity, but it is believed that the ancient Sumerian civilization, which flourished in the southern part of Mesopotamia during the fourth and third millenniums BC, was first to practice this process. From a historical perspective, meat curing can be defined as the addition of salt to meats for the sole purpose of preservation, that is, to inhibit or deter microbial spoilage. The preservation of meat resulted from necessity, so that products could be held for extended periods for later consumption. At some point, it was discovered that ‘certain’ salts (i.e., those containing saltpeter) could impart a unique color and flavor to meats. Granulated or grain salt was formerly called ‘corn,’ which comes from the Old Norse, ‘korn,’ meaning grain; thus, when beef was sprinkled with these salts, corned beef was the resultant product. Scientific principles of meat curing were not applied until the early part of the twentieth century when the growing meat packing industry began to search for ways to improve quality and to extend the shelf life of products. It was discovered that nitrite, not nitrate as originally thought, plays a multifunctional role in the meat matrix: Nitrite is responsible for developing or ‘fixing’ the characteristic color associated with cured meats; for creating a special flavor so that one can

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confusion with common salt; this is why they are sometimes called ‘pink’ curing salts. Prague powder 2 (Cure 2) A mixture of 1 oz of sodium nitrite (6.25%) along with 0.64 oz of sodium nitrate (4%) to 1 lb of salt. Both Cure 1 and 2 contain a small amount of FDA-approved red coloring agent, which gives them a slight pink color thus eliminating any possible confusion with common salt; this is why they are sometimes called ‘pink’ curing salts. Salometer A specially graduated hydrometer that measures the strength of brines. A 100° salometer reading is equivalent to a 100% saturated salt solution (26.5% salt). Silent cutter Equipment for mixing and chopping meat and other products through the use of rotating knives. Wet curing Sometimes called brine (salt and water), sweet pickle (sugar added), or immersion curing, this process has been traditionally used for larger cuts of meat like butts and hams. It is accomplished by placing the meat in a wet curing solution (water, salt, nitrites, and sometimes sugar). Sugar is added only when curing at refrigerator temperatures; otherwise, it may begin fermentation and start to spoil the meat.

distinguish the flavor of corned beef from that of roast beef; for imparting antioxidant activity to the cooked product, thereby extending its shelf life; and for suppressing the outgrowth and production of toxin from the anaerobic bacterium, Clostridium botulinum. Including nitrite at a minimum of 120 ppm also slows the growth of other pathogens such as Clostridium perfringens and Listeria monocytogenes as well as spoilage bacteria. Meat color is an essential quality attribute of processed meat products and thus a key factor when consumers make their selections. The pigment responsible for the characteristic color of cooked cured meat products is nitrosyl myochrome/ myochromogen (sometimes also referred to in the literature as nitrosyl hemochrome/hemochromogen). It is formed between the reaction of nitrite and the endogenous Fe–protoporphyrin (i.e., heme) meat pigments on thermal processing. In drycured ham such as Parma ham, salt is added but not nitrate/ nitrite, and there is careful control of temperature and humidity during processing. During the long ripening period, a Zn–protoporphyrin with a stable bright red color is formed; this pigment has been isolated as the main component of red pigments found in these dry-cured hams. The industry has evolved to the point that quite a diverse list of cured meat products offering great taste, convenience, and versatility is available to the consumer. On account of

Encyclopedia of Meat Sciences, Volume 1

doi:10.1016/B978-0-12-384731-7.00114-8

Curing | Production Procedures household refrigeration, the original need to cure meats no longer exists; nevertheless, consumers have become accustomed to certain products in their diet and the increase in variety of products that curing offers. For these reasons, as well as others, the public still demands the availability of cured meat products in the market.

Regulations Before outlining some curing production procedures, it is important to note that each country has its own set of regulations as to what additives are permitted in a particular meat product, what additives are prohibited, to what maximum level an additive may be used based on the weight of the meat block or the entire formulation, how the finished product must be labeled, etc. It is not within the scope of this article to detail all of the guidelines and exceptions to meat regulations for each country. Therefore, any quantity of an additive specified in this treatise is used solely for the purpose of illustration. For example, sodium nitrite is employed at the level of 156 ppm (0.4 oz 100 lb−1 meat) in comminuted products in the US, but this level is based on the weight of the meat block and not that of the finished emulsion or pumped product. In most European countries, ingoing nitrite levels are 100 ppm based on the meat. Canadian regulations, in contrast, permit the use of nitrite in not only the meat but also the complete emulsion or pumped product at the level of 200 ppm. Bacon is an exception to the rule, as ingoing nitrite levels are reduced in most countries: The regulated level in Canada and the US is 120 ppm or 0.012% based on the weight of the pumped product. Knowledge of the regulations is critical for domestic production. For instance, the USDA considers anything with less than 120 ppm uncured and must be labeled as such. Furthermore, processors who want to export their wares to foreign markets must adhere to each country's meat regulations/standards of identity.

Basic Ingredients Needed for Curing Meat The meat used in formulations can vary markedly, so careful selection of species and muscle type is required to produce a consistent product. The concentration of myoglobin present in the meats selected will ultimately determine the color characteristics of the cooked cured product. The quantity of meat used in a formulation is called the meat block. Seasonings and other nonmeat ingredients are added based on the weight of the meat block. Typically, a meat processor will calculate the formulation of products based on 100 lb or kilogram batches, but, of course, the actual weight of the batches produced will depend on the equipment available to the processor.

Water or Ice Water serves as the carrier for curing ingredients in most commercial ham and bacon processing operations. It replaces moisture lost during thermal processing and smoking. In some

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cases, additional water is pumped into hams, so that the weight of the finished product exceeds its fresh, uncured weight (i.e., the green weight). In the US, labeling of extended products that include added water and other ingredients is based on the minimum meat Protein Fat Free (PFF) percentage. For example, hams with a minimum PPF of 20.5% are labeled as ham. Hams with a minimum PPF of 18.5% are labeled as ham in natural juices. The quality of the water or ice added to meat products directly, or in the form of the brine, can have a profound effect on the product. Low-quality water, as a result of contaminates, pH fluctuations, different sources or seasonal variation, can cause a reduction in the shelf life and create aftertastes and off-colors in products.

Salt Salt or sodium chloride is the most basic ingredient for curing and is used in every formulation. Although it still affords some preservative effects, salt is primarily added to flavor meat and to solubilize myofibrillar proteins for the product's yield and texture. The amount of salt used in dry cures and brines can vary considerably but to some extent is self-limiting. Too little salt can cause excessive product shrinkage (i.e., not sufficient water-holding capacity), poor binding or emulsion stability (i.e., not sufficient protein extraction), and a reduced shelf life, whereas too much salt can impart an undesirable taste. Only food-grade salt of high purity (i.e., free of nitrite, nitrate, and heavy metal ions) is used in meat processing, as impure salts can impart flavor and color defects to products. One type of salt that has been getting more and more attention is sea salt. Sea salts are as varied as the water from which they are made. This is a favorite additive in natural and organic products. These salts, however, can cause problems because of contaminates including nitrites, nitrates, and heavy metals. The level of salt ranges typically from 1.0% to 2.8% in finished cured meat products.

Cure After salt, sodium nitrite is the most important ingredient in the cure. It provides the characteristic color and flavor and works with salt to offer bacteriostatic protection against anaerobic bacteria such as C. botulinum and C. perfringens in processed meat products. It is generally added to pickles or meat formulations in the form of a ‘curing salt.’ Because it is difficult to accurately weigh out the small quantities of nitrite needed for a formulation, nitrite is preblended with sodium chloride to give a commercial curing salt. Prague powder and Cure 1 are examples of blends for such a curing salt, which is routinely utilized in North America. Prague powder 1 is a mixture of 1 part sodium nitrite and 15 parts sodium chloride (i.e., 1 oz NaNO2 in 1 lb of salt, or 6.25% NaNO2). The chemicals are combined and crystallized to assure even distribution. An anticaking agent such as glycerin or 1% (w/w) sodium carbonate is commonly incorporated, and in some preparations a red food-grade dye, FD&C Red Dye 3, is added so that one can distinguish this ‘curing salt’ from regular salt in the processing plant. Depending on the ingredient supplier, the curing salt goes by different names, including sure cure, insta-cure, speed cure, modern cure, and pink curing salt. Prague powder 2 is a mixture of 1 part sodium

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nitrite, 0.64 parts sodium nitrate, and 14.36 parts sodium chloride (i.e., 1 oz NaNO2 and 0.64 oz NaNO3 in 1 lb of salt, or 6.25% NaNO2 and 4% NaNO3). It is ‘primarily’ utilized in dry curing of meat products that do not require cooking, smoking, and refrigeration; however, Prague powder 2 can also be used in slow cured products that are cooked. In Europe, it is often referred to as bacon-curing salt. When purchasing cure units for specific products (e.g., pepperoni preparation), the curing salt is packaged in a separate bag from all other nonmeat ingredients. This is important because nitrite can react with amines in seasonings, leading to the formation of N-nitrosamines. For example, in a 500-lb meat block formulation (i.e., for a US product), 1.25 lb of curing salt at 6.25% nitrite would be placed in a separate bag and put inside or attached to the outside of the main seasoning/binder bag. The operator would only have to add a bag of each product to the formula without additional weighing of the seasonings.

Sweetener Sweeteners in the form of table sugar (i.e., sucrose), brown sugar, dextrose, corn syrup solids, honey, sorbitol, or lactose are often added to meat products as a flavoring ingredient. Their addition level can vary from 1% to 3% and is product dependent. These sweeteners help to counteract some of the sharpness imparted by salt and have a moderating effect on flavor. Dextrose in particular assists in the formation of the characteristic brown color on the external surface of country hams and bacon during thermal processing via the Maillard reaction and caramelization. The term ‘glucose’ used by some in the meat industry is a bit of a misnomer; it refers to corn syrup solids or ‘glucose solids,’ which is a hydrolyzed starch product, and not dextrose itself. Unlike corn syrup, corn syrup solids have a low sweetening power; they have different dextrose equivalents and hence browning potentials. Corn syrup solids are added to meat products for bulk and their ability to hold some water. Lactose also has a weak sweetening capability and may contribute bitterness in certain meat products but is present in sausages when nonfat dried milk is included in the formulation.

Erythorbate Sodium erythorbate and ascorbate are reducing agents/cure accelerators, which speed up the conversion of nitrite to nitric oxide and thereby shorten the time required to complete the curing process. Residual amounts of erythorbate will also help stabilize the finished product's color. Moreover, erythorbate and ascorbate help to prevent the formation of carcinogenic N-nitrosamines that may form from secondary amino residues and residual nitrite in bacon.

Polyphosphates Phosphates are sometimes added to improve the retention of moisture and to reduce the shrinkage or purge (i.e., cookout) that occurs during the heat processing of hams and bacon. Alkaline phosphates raise the pH of the product, and in

doing so, help to solubilize muscle proteins, to improve the bind, and to increase their water-binding capacity and thereby the yield of the finished product. When phosphates are added to brines, it is not uncommon to obtain finished yields for intact hams and shoulders (i.e., picnics) of more than 100%. Polyphosphates have also been reported to retard the development of warmed-over flavor (WOF) and lipid oxidation, supposedly by their action as a metal ion chelator. The maximum regulated level of phosphate in the product formulation in the US is 0.5% with typical usage for hams, bacon, and cured sausages at 0.3–0.5%. Metallic and soapy flavors in meat products have been detected if phosphate levels are greater than 0.45%.

Seasonings and Flavors Whole or ground spices, spice oleoresins, and seasonings (i.e., compounds containing one or more spices, or spice extractives, which are added to a food during its manufacture or in its preparation before serving) may be used by processors to develop distinctive flavors and to create special cured products. Seasonings should not be overwhelming or diminish the product's natural flavor, but potentiate the product with a blended, well-rounded flavor with no perceptible, undesirable aftertaste. Most flavors are mixed with a carrier such as a sweetener or salt. In recent years, however, flavors have been mixed in or encapsulated by starches, milk ingredients, or soy protein carriers. Today, preformulated cure units with specific flavors are available to processors. For example, California ham spice is a cinnamon and clove flavor mixed into salt or sugar, which is incorporated into ham formulations at levels of o0.3%. Maple seasoning is a flavor that is added to a sweetener to impart a maple flavor in ham and bacon products. However, honey flavor is usually added directly to the meat product from a pure source. When comparing full-fat formulations with reduced-fat formulations, it is important to note that there will be a difference in flavor between the two products even if the same amount of seasoning is added. Low-fat formulations typically use more water to help soften the texture of the finished product, and water will carry the flavor differently. Excess seasoning in lowfat products can at times impart a very unpleasant metallic or astringent taste which lingers on the palate. Thus, the choices and addition levels of seasonings to meat formulations are a bit of an art, as the final balance of flavors will be dictated by the specific product in question. Even if the quality of meat used during formulating is of the highest standard, it becomes of little importance when the product is not properly seasoned. Many seasoning companies are known by the industry to be predominantly suppliers of meat seasonings. Historically, there are two reasons for this. First, most of the smaller seasoning houses were founded by large meat companies so as to provide seasonings to their processing operations. Second, some seasoning houses marketed meat seasonings because of the technical expertise available from their personnel. Not only did these companies sell seasonings, but they also provided other ingredients like smoke flavors and sausage casings as well as the technical support for the preparation of valueadded meat products.

Curing | Production Procedures

Formulating Meat Products Formulating any food product is much more than simply recipe development. In fact, some may even call it an art. It involves detailing the required processing steps and in what particular order they must be carried out to produce a highquality finished product. Decisions when formulating meat products can entail the selection of meats and their levels of addition, choice of nonmeat ingredients such as salt, sweeteners, binders and seasonings, method and length of curing, grind or chop size of meat and fat, oven/smokehouse schedules, type and diameter of casings, as well as type and method of packaging. Formulating meat products also requires preparing a product which meets recognized characteristics set out by the country's standards of identity for that product. For meat companies, innovation is one of the single most important factors in building and maintaining a successful product or brand. A brand can be well recognized, but if over time that brand does not continue to offer value to consumers, it will soon be eclipsed in the market. When designing meat products, it is practical to formulate by ingredient weight, which is based on the amount of the meat block. When formulating the seasonings, the processor must work in the weight of seasoning per 100 lb or kilogram of meat. Quantities can then be easily converted to percentages and the seasoning formula determined. For meat blocks not in 100 lb or kilogram increments, the percent usage of spice, oleoresin, or seasoning is calculated per pound or kilogram and then multiplied by the weight desired to determine the quantity required. Many processors weigh out the dry ingredients in a controlled-access room where the temperature and humidity are carefully monitored. After weighing, the critical components are often packaged and then assembled for batch production. A checklist must be prepared and verified in order to ensure that all of the materials are accounted for. Meat processors keep very detailed records of all formulas, and most are proprietary. The formulas are designed so that costs can be easily calculated and updated as needed, especially in the case of least cost formulation products. Standard blending or formulation documentation includes a list of ingredients, the weight of the individual ingredients in one seasoning unit, the percent of each ingredient in a batch, as well as the laboratory and plant code numbers.

Brine Preparation One of the most important steps in ham and bacon production is brine preparation. Brine is a water-soluble solution containing salt, cure (e.g., Prague powder), phosphate, sugar, sodium erythorbate, and seasonings. All of the flavoring materials should be water soluble. There are two schools of thought regarding the temperature of water used for brine preparation. Some processors use warm water to help the dissolution of added solids and then allow the brine to cool to 0–2 °C (32–35.6 °F) before its application to meats. Others have concerns that warm water may cause chemical reactions to occur prematurely (e.g., conversion of nitrite to nitric oxide and then release of nitrogen dioxide gas from the brine) and thereby reduce the brine's efficacy. Such proponents favor the

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preparation of brines using cold/ice water. Whichever approach is employed, a known weight of water is measured, and all quantities of brine additives are weighed out separately. If using phosphates in the brine preparation, they should be added first and mixed thoroughly with high-speed shearing to ensure their complete dissolution. Other ingredients are added to the brine based on their solubility. Sodium erythorbate and soy isolate or concentrate are both difficult to suspend. Soy, if used, should always be added following the manufacturer's instructions including how much and if shear is necessary to get the plant proteins into suspension. Any product that settles out during brine injection could potentially cause problems in the finished product. Salt is then added and dissolved, followed by the cure and any remaining ingredients such as sugars and water-soluble spice mixtures. Nitrite is almost always added last, or until just before the brine is used, to ensure that less is lost to the environment. Brines are usually covered and held in a cooler – to reach or maintain a temperature of 0–2 °C (32–35.6 °F) – before use. It is important to note that some additives like soy, which are not completely solubilized, require agitation when processing/injecting.

Application of Cures There are a few means by which meats can be cured. The basic methods include the following: 1. Dry curing – in this technique the curing ingredients, usually salt, sugar, nitrite, and nitrate, are mixed together and rubbed over the surface of the meat cut. The product is then placed in a cool room and the ingredients are allowed to penetrate by diffusion through the muscle tissue. The main disadvantage of this approach is that it is slow and in thicker cuts of meat, spoilage organisms can begin growing before the preservatives reach all parts of the product. More details about dry curing of meats are provided in the preceding article. 2. Brine curing – a brine is prepared by combining the salt, cure, and seasonings in water, which serves as a carrier. The strength of a brine solution or ‘pickle’ is determined by the amount of salt present. A salometer is a specially graduated hydrometer that measures the strength of brines at a particular temperature (usually 40 °F/4.4 °C) and is calibrated to indicate the degree of salinity (this is essentially a measure of the brine's density). A 100° salometer reading is equivalent to a 100% saturated salt solution, which is typically 26.5% salt (depending on temperature). Larger processors prepare stock solutions of brine at a 100° salometer reading and then formulate working pickles with additional additives at lower strengths. The presence of sweeteners, phosphates, nitrite, and erythorbate in brine will affect salometer readings to an extent. Typical pickles have strengths of 60–70°, with 70° brine being the most common. For brine immersion or cover pickling, the product is simply immersed in the brine for a specified period. For example, hams and shoulders are normally cured for 2–2.5 days per pound in 70° brine. Even though the penetration of ingredients into the muscle tissue may be faster than in dry curing, this technique also suffers from

446

Curing | Production Procedures

slowness and is not widely employed by industry. More details about brine curing of meats are provided in another article. 3. Multiple-needle (stitch) pumping – a brine is prepared and then injected mechanically under pressure through needles, which are perforated along the stem near the point, into primal cuts of meat. In this multiple-needle injection technique, a conveyor belt carries meat under a bank of offset needles through which brine is pumped until a desired target weight is achieved. The spacing of the needles, their size, the pumping pressure, spray pattern, and the dwell time between strokes are important variables to ensure good distribution and retention of the pickle. The brine injected into commercial mild-cured products is typically a 70° pickle. The main advantages of multipleneedle pumping include increased product yield, greatly reduced labor costs, and time required for production. After pumping, some products are cooked immediately, whereas others are further processed by immersing them in a brine cure for a period (e.g., Canadian bacon) or subjecting them to a mechanical operation such as tumbling. 4. Tumbling or massaging – although strictly not a basic curing technique, tumbling or massaging of pickle-injected meat cuts is employed to speed up the curing process, to facilitate extraction of salt-soluble proteins, and to improve the texture, bind, water-holding capacity, and yield of the finished product. Tumblers are large stainless steel units that rotate in a circular fashion for a period of time. Nowadays practically all units have vacuum capabilities. Inside, pieces of meat are continuously lifted up by baffles to the upper part of the machine. From here they fall, striking the meat mass below, and produce an intense mechanical action suitable for high-yield products. Muscle fibers are disrupted by this mechanical action, which makes cellular membranes more permeable and facilitates the distribution and absorption of brine. Some degree of massaging also occurs as the chunks slide over each other as the tumbler turns. Tumblers typically provide somewhat more of a destructive effect than massagers on account of the impact force generated from the mechanical action. Thus, not all cured meat products can be tumbled (i.e., bone-in hams). A fitting example for the benefits of tumbling comes from ham production: Hams processed in this fashion are more uniform, as brine uptake is more tightly controlled and pickle pockets are reduced. The tighter control of pickle uptake results from the ability to pump the hams at, or somewhat below, the target pump and then adjusting the product's uptake to the exact percent pump by adding pickle directly to the tumbler. Without the presence of tumblers and massagers in meat processing operations, the higher processing yields and lower production costs associated with a number of value-added meat products could not be achieved. 5. Chopping or blending – dry curing ingredients are distributed directly into ground meat products during the grinding, chopping, and emulsification steps involved in batter preparation. Particle size is important in this process. Larger particles will require more time for cure penetration than very small ones. The particle size can be controlled by the grinder plate size or time in the chopper.

Specific Cured Products Bacon In North America, bacon is manufactured from pork bellies. The preparation of the belly is dependent on the desired characteristics of the finished product. Bellies may be cured with or without skin attached. Skinless bellies produce a product that has smoke color and flavor on all sides, whereas skin-on-bellies are usually derinded just before slicing and are identifiable by their distinct white fat. In most preparations, the bellies are first skinned using a skinning machine and then trimmed of ragged edges by knives. Excessive lean at the butt end is trimmed and used for sausage production. In former times, the bellies were placed in high-saltcontaining brines with the lean side down for 4–5 days or were dry cured for 10–14 days. Modern processing operations, however, cannot afford these time or space constraints; green bellies (raw noninjected) are pumped with brine to a specific percentage using a multineedle pickle injector. The injection operation dramatically speeds up the curing processing and also results in weight gain and an even distribution of the cure in the product. In some operations, the bellies are tumbled or massaged after injection for a short period of time (i.e., less than 60 min) with additional brine. Brine pickups of 18–30% can be achieved with a uniform distribution of the cure. However, bacon in the US must return to green weight. The processed bellies are then placed on combs and hung on trees or trucks for thermal processing and smoking. The bacon is partially cooked in an oven/smokehouse according to either a one- or three-step cook schedule until a final internal temperature of ~57 °C (135 °F) is reached; even so, it is still considered as a raw product. Bacon is smoked during all or part of the cooking cycle, depending on the requirements of the desired final product. After processing, the bacon is chilled in a tempering cooler to an internal temperature of −4.4 or −3.3 °C (24–26 °F) before pressing, slicing, and vacuum packaging. Cooling the product allows the bacon to retain its shape during pressing and facilitates slicing. The pressing operation involves placing slabs of processed bacon in a large forming machine where they are compressed to a relatively uniform width and thickness. The pressed bacon is sliced to a set thickness using a high-speed slicer and then graded according to premium slices, secondary slices, and ends or pieces. The shingled bacon is then conveyed to a packaging machine where it is typically vacuum packaged. Microwaveable bacon is a more recent product in the marketplace. It is bacon that has been thermally processed for a sufficient length to develop the characteristic flavor and texture of fried bacon. This fully cooked product is sliced and then packaged in special packs designed to enhance microwave heating. In this respect, the product can be prepared faster without significant fry out from fat. The convenience and little mess resulting during microwave processing afford an attractive product to food service operators and to the consumer. Canadian-style bacon, which is sometimes referred to as back bacon, is manufactured using the center portion of boneless pork loins (i.e., longissimus dorsi). Thus, it is a very lean product. Boneless loins are pumped with brine and then held in a cover pickle for 2–5 days. Once removed from the

Curing | Production Procedures pickle, the loins are rinsed with cold water, stuffed into casings, and hung in an oven/smokehouse, where they are cooked to an internal temperature of ~70 °C (158 °F). Canadian bacon is sold either sliced or in chunk form. Wiltshire bacon is made from selected hogs weighing between 68 and 90 kg with special cutting procedures for the carcasses; that being, the shoulder, loin, belly, and ham are left as one piece, whereas the foreleg is removed at the knee and the hind leg at the hock. Additionally, the tenderloin, ribs, neckbone, backbone, aitchbone, skirt, and loose fat are also cut out. The Wiltshire sides are cured by pumping and then placing them in a cover pickle for 7–10 days. After this period, the sides are removed from the pickle and product is held under refrigeration conditions for maturation, which lasts anywhere from 2 to 14 days. The sides are then usually smoked before being shipped to market.

Hams Hams are very popular cured meat products that are prepared from the hind leg of pork. Meat sizes can vary from whole muscles to relatively small chunks, which are restructured. Some processors are matching muscles to make small 2–3 lb hams as opposed to large whole hams or chunked and formed hams. Various types of hams can be prepared and they include the following: traditional bone-in hams; semiboneless hams; boneless, premium hams; and boneless, sectioned/chopped and formed hams. Most hams are pickle cured with brine consisting of salt, cure, sugar, phosphate, and erythorbate. Once cured, hams can be stuffed into fibrous casings and processed in an oven/smokehouse or, as in the case of some sectioned/chopped and formed hams, be processed using cook-in-a-bag technology to produce a fully cooked ham.

Traditional bone-in and semiboneless hams Bone-in hams are typically prepared from the whole pork leg with the foot removed. Hams are usually separated from the loin by cutting between the second and third sacral vertebrae parallel to the angle of the hock joint. The resulting whole intact hams contain only three bones – aitch, body (i.e., femur), and shank. When the aitch- and shankbones are removed, the ham is referred to as semiboneless. The aitchbone is sometimes removed alone when preparing spiral-cut country-cured hams. In older times, before processing, hams were trimmed of some collar fat by line workers. At present, processors who do not have abattoirs and bring in raw meat typically purchase Institutional Meat Purchase Specifications (IMPS) 401 or 402 series hams, which already have partially skinned collar fat removed or are fully skinned (402). A prepared brine is injected into the muscle tissue at a certain percentage pump. The product may be immersed in a cover pickle before netting and is then placed on a tree or truck for thermal processing. The ham is thermal processed (with or without smoke), chilled, packaged, and then boxed. Bone-in hams are comprised of the butt, center, and shank. The hams may be sold whole or cut into butt and shank sections. For bone-in hams, special care is needed when using a multineedle pickle injector to avoid potential damage of the needles should one hit a bone during mechanical treatment.

447

Specially designed bone-in injectors are recommended for use with bone-in hams. Consequently, in many small operations, hams are pumped by hand. Placing the hams in a tumbler or massager for a period to distribute the cure throughout the product aids in creating a uniform cure and prevents against bone souring; however, if tumbled too long, this can also create problems. Hams, and picnics to a lesser extent, may also be cured by artery pumping. This involves pumping brine directly into the tissue's vascular system. A needle is usually inserted in front of the branch in the femoral artery so that the pickle can be distributed throughout the entire ham. Care must be exercised, however, to ensure that blood vessels are not ruptured by excessive pumping pressures. The pumping schedule generally calls for adding 8–10% by weight of the pump pickle. There are some problems, however, with this technique. First, the arterial pathways in the muscle are not uniform, thereby resulting in uneven curing. Second, it is generally recommended to hold the ham under refrigeration conditions after injection to permit not only equilibration of the cure but also the fixation of the cured color. Most important, the success of arterial injection is dependent on attentive work during slaughter and cutting as well as subsequent handling procedures in order to guarantee that the arteries are left intact. Owing to the inherent difficulties with this technique, it is not as often employed as it once was.

Boneless, premium hams The usual muscle classes for premium hams from the leg area of hogs include semimembranosus–adductor and biceps femoris–semitendinosus. The muscle tissue is generally trimmed, deseamed, and boned. The boneless meat is then pumped via a multineedle injector to a certain pump percentage and then subjected to massaging or tumbling to evenly distribute the cure. In instances where the targeted pumping gain in the hams has not been achieved, brine is added to the tumbler for pickup of the additional amount needed. After tumbling, the muscles are netted together or placed in casings; they are manufactured in either round or flat shapes. In some cases, ham molds are placed on the product before thermal processing to give them the required shape. Round boneless hams are held in cellulose casings, whereas flat hams are prepared by pressing boneless hams together. Before pressing, the hams are stuffed into stockinettes, cellulose, or collagen casings. The pumped meat is then thermal processed and smoked. Afterward, the ham is chilled and finally vacuum packaged. In some instances, the hams are cut in half or to specific pound quantities before packaging.

Boneless, sectioned/chopped and formed hams These hams are made virtually in the same manner as premium hams except that the biceps femoris–semitendinosus muscles are chopped or sectioned into smaller pieces along with muscles from the shank and the knuckle. The meat from boned hams or ham pieces may be used fresh or after freezing and thawing. All excess surface fat and seam fat should be removed. Brine containing salt, cure, sugar, phosphate, and erythorbate is formulated and pumped into the pieces of ham (typically a 15–30% pump). Tumbling or massaging is used to extract myofibrillar proteins from the muscle tissue to cause the meat pieces to be glued or stuck together. In some cases, shank meat or lean ham trim is finely chopped in a bowl

448

Curing | Production Procedures

chopper with added water, salt, phosphate, and cure. Approximately 5–10% of this mixture (based on the pumped weight of hams) is transferred to a massager containing pumped hams. The meats are massaged for 6–8 h and then tightly stuffed into fibrous cellulose or collagen casings of approximately 12.5 cm. The meat chunks should be tightly stuffed to force the pieces together so that they will bind during heating. The product is cooked in an oven/ smokehouse. The amount of smoke applied will vary from none to heavy, depending on the desired characteristics for the finished product. During the thermal processing operation, all hams must reach a minimum of 60 °C (140 °F), as this temperature will kill any Trichinella spiralis. This nematode parasite is not really a problem anymore; present day microbiological concerns over Salmonella spp. and Escherichia coli dictate an end-point temperature of 70 °C (158 °F). Because thermal processing is employed to ‘set’ the premium and section and formed hams by means of heat coagulable proteins, these hams need to reach a temperature of 72 °C (~162 °F). Afterward the hams are cooled to approximately 2 °C (35.6 °F) before packaging. Chilling must be accomplished in a specific time frame to ensure food safety. A chopped and formed ham is a variation of a sectioned and formed ham. In the former, the meats used are usually smaller pieces. A formulation for a Pullman ham, a typical chopped and formed ham, is given in Table 1.

Dry-cured hams Although dry-cured hams are not as common in North America (the possible exception being the US country-cured hams for southeastern markets in Virginia, West Virginia, Kentucky, Tennessee, North Carolina, South Carolina, and Georgia), they are extremely popular in the Mediterranean region and are revered for their unique flavor as well as other characteristic sensory attributes. In Spain, two important drycured products are Iberian and Serrano hams; their production in 1993 was approximately 181 500 ton. During processing there is a loss of water, and diffusion of salt throughout the ham leads to a gradual stabilization of the product, due to a drop in the water activity. Simultaneously, there is a slow degradation of proteins and lipids that results in an accumulation of free amino acids and fatty acids, respectively. Details on the processing of Iberian and Serrano dry-cured hams are described in Table 2, but briefly include the following steps: 1. reception and classification of hams, and then presalting where a mixture of curing ingredients (i.e., salt, nitrate, and/or nitrite) and adjuncts (i.e., ascorbic acid) are rubbed onto the lean muscle surface of the meat; 2. salting, where hams are then placed fat side down, entirely surrounded by salt and arranged in single layers without touching one another. As there is no water added, the curing agents diffuse slowly into the ham and are solubilized by the original moisture present in the muscle tissues. This period usually takes 8–10 days (i.e., 1–1.5 days per kg weight) at temperatures between 2 (35.6) and 4 °C (39°F); 3. during the post salting stage, a complete salt equalization within the hams occurs. The temperature is kept less than

Table 1

Formulation sheet for a chopped and formed hama

Product: Pullman ham Yield over green weight: 145% Batch size: 116 kg Ingredients

Concentration in product (%)

Level (%)

Meat Ham meat Shank meat Brine Water/ice Salt Dextrose Glucose (i.e., corn syrup solids) Sodium tripolyphosphate Sodium erythorbate Prague powder Flavor

Quantity needed (kg)

68 12

2.3 1.4 1.4

77.573 7.411 4.511 4.511

27.30 2.67 1.63 1.63

0.50

1.611

0.58

0.05 0.31 1.0

0.161 1.000 3.222

0.060 0.36 1.16

a

Courtesy of Mr. Daniel J. Prefontaine, President, Saskatchewan Food Industry Development Center, Saskatoon, SK. Note: Instructions: • Pass chilled ham meat through a kidney plate. • Grind chilled shank meat through a 0.12 in. plate. • Transfer ground shank meat with about half of the phosphate, salt, Prague powder, erythorbate and water/ice to a silent cutter. • Cut until the product is creamy, then add all remaining dry ingredients and water/ ice, followed by blending. • If all meat in the silent cutter is lean then the temperature is not an issue, but if fats have been added, the temperature must be monitored. • Once complete, transfer the mixture to a vacuum tumbler and add the coarse-ground ham meat to it. • Tumble the meats under vacuum for 1 h at high speed. • Stuff product into water-cook casings. • Place in 4 × 4 molds. • Cook product in a water bath/steam kettle to an internal temperature of 72 °C (~162 °F). • Cool down product by immersing it in cold water. • Transfer product to a cooler, chill, and when ready slice and vacuum package.

4 °C (39 °F) for a period not less than 20 days but not exceeding 2 months; 4. the last and more complex stage is the ripening/drying stage. Hams are placed in natural or air-conditioned chambers and subjected to different time–temperature/ relative humidity (RH) cycles. The temperature is usually maintained between 14 (57) and 20 °C (68 °F) with a RH decreasing from 90 to 70%. Aging of hams takes anywhere from 9 to 24 months. For example, the ripening period for Serrano hams is between 9 and 12 months and for Iberian hams, it can be extended up to 18 or 24 months. The quality of these two hams depends on the raw materials and the ripening conditions employed. Iberian drycured ham is produced from an autochthonous pig that is found in the southwestern region of Spain. These swine feed on pastures or stubble fields during their growing period (until 12/16 months of age, 55/75 kg) and their nutritional requirements are completed with cereals such as corn and

Curing | Production Procedures Table 2 Scheme of the approximate conditions for the processing of Serrano and Iberian dry-cured hamsa

Table 3

449

Formulation sheet for bologna

Product: Bologna Serrano ham Salting

Post salting

Dry curing First phase

Second phase

Third phase

Fourth phase

Total Time

Iberian ham

T 0–4 °C RH 75–95% t40.65 and o2 days kg−1 T 0–6 °C RH 70–95% t440 and o60 days T 6–16 °C RH 70–95% t445 days T 16–24 °C RH 70–95% t435 days T 24–34 °C RH 70–95% t430 days T 12–20 °C RH 70–95% t435 days

T 6–16 °C RH 60–80% t490 days T 16–26 °C RH 55–85% t490 days T 12–22°C RH 60–90% t4115 days

t4190 days

t4365 days

Ingredients

Level (%)

Quantity needed (kg)

Lean pork trim, 80/20 Lean beef trim, 85/15 Pork trim, 50/50 Water (as ice) Salt Sodium tripolyphosphate Garlic powder Paprika Modified food starch White pepper Prague powder Sodium erythorbate Onion powder Nutmeg Ginger

39.24 22.00 22.00 10.0 1.80 0.35 0.05 0.25 3.5 0.13 0.30 0.05 0.06 0.17 0.10

39.24 22.0 22.0 10.0 1.80 0.35 0.05 0.25 0.75 0.13 0.30 0.050 0.060 0.17 0.10

Note: Instructions:

a

Abbreviations: RH, relative humidity; T, temperature; t, time in days. Source: Reproduced from Toldrá, F., 2002. Dry-Cured Meat Products. Trumbull, CT: Food & Nutrition Press, Inc.

barley. During the fattening period, three types of feeding regimes, known as montanera, recebo, and cebo, are possible. For montanera, the basic food is the acorn (Quercus ilex, Quercus rotundifolia, and Quercus suber) and the feeding period lasts from October to December or until a final weight of approximately 160 kg is achieved. For recebo, the acorn is complemented with cereals and mixed feeds. For cebo, only cereals and mixed feeds are used. Meat from acorn-fed pigs commands the highest price and the dry-cured hams so prepared offer a high degree of marbling (resulting from the finishing lipid-rich acorn diet), firm texture, and exquisite characteristic flavor. The Serrano ham is produced from different crossbreeding of white pigs and has lower marbling, firm texture, and a typical flavor. The intensity of the flavor can be controlled by the length of time the ham is allowed to ripen/dry. Complex biochemical reactions, mainly enzymatic, proteolytic, and lipolytic in nature, occur during the dry curing process and contribute to the development of an adequate texture and characteristic flavor.

Corned Beef Traditionally, corned beef is prepared from the brisket; however, the demand for leaner meat products has some processors preparing it from muscles of the round. The basic corning process used today is multiple-needle injection of pickle into the beef. The pickle used in the preparation of corned beef is similar to that employed in ham and smokedmeat manufacturing. If boneless briskets are used, they tend to be pumped to 120% of green weight, whereas rounds are generally pumped to only 110%. The injected beef is then

• Weigh out all ingredients and keep them separate. • Grind all chilled meats through a 0.12 in. plate, but keep meats separate from one another. • Transfer ground lean meats, salt, Prague powder, erythorbate, and half of the ice into the silent cutter. • Chop to 4 °C (39 °F) and then add ground pork trim (50/50) and the remaining dry ingredients along with the ice. • Chop on high speed until a temperature of approximately 13 °C (~55 °F) is reached. • Transfer the batter to a stuffer, and stuff into cellulose casings. • Heat process and smoke in a smokehouse to 72 °C (~162 °F). • Cold water shower to reduce internal temperature of product to 32 °C (~90 °F). • Transfer product to cooler, chill and when ready peel and vacuum package.

placed in a cover pickle containing additional spices and herbs, such as bay leaves and allspice, for a few days. Prepackaged corned beef is sold either uncooked or as a readyto-eat product. In the latter case, the corned beef is cooked in water or steamed to an internal temperature of 67 (~153) to 72 °C (~162 °F).

Frankfurters, Cured Sausages, and Comminuted Meat Products Frankfurters, cured sausages, and comminuted meat products such as bologna, salami, and pepperoni are prepared as a meat batter. In its simplest form, a meat batter contains water, protein, fat, and salt. The general steps in preparing sausage products include grinding of meat, chopping of meat, additive addition, stuffing, linking, cooking, peeling, slicing, and packaging. As a general rule of thumb, better meat quality will give a higher quality batter and final product. A typical formulation for bologna is provided in Table 3. There is a particular order of steps which one must follow when preparing batters. Meats to be used are divided into groups according to how much fat is present. For example, there is the lean or 95/5 (i.e., 95% lean muscle tissue containing 5% intramuscular fat), followed by 80/20 and then the fatter 50/50 trim. In the case of products containing pork, the majority of fat and fatty trims should be hard fats from the

450

Curing | Production Procedures

shoulder, ham, back fat, or jowls. Softer fats such as belly trimmings should be limited, as they can cause fat caps and soft texture in the finished product. Each meat type is ground separately to a final grind size, depending on the product of choice. Grinding is a particle size reduction step in which pieces of meat are continuously forced through the holes of a metal plate between the arms of a rotating multibladed knife. The holes bored into the plate have specific diameters (e.g., 3.2, 6.4, 9.5, 12.7 mm; or 0.12, 0.25, 0.38, 0.5 in., respectively). Meats must be comminuted in two or three steps with a sequential reduction in the grind size. It is important to remember, however, that the meats must be kept cold during any grinding operation to prevent smearing/liquidization of the fat. Ground meats are transferred to a grinder mixer, a bowl chopper, or a silent cutter. Here the mechanical action of the vertically positioned rotating knives in combination with added salt and phosphate will extract myofibrillar proteins from the meat; extracted proteins will help to immobilize fat particles and form a three-dimensional network of filaments that contributes to the overall texture as well as the waterand fat-binding properties of the finished product. The sequence of batter preparation goes as follows: lean meat, phosphate, salt, cure, erythorbate, and half the ice/water are added to the chopper. The chopping process creates sufficient shear to comminute meat and fat into fine particulates as well as to extract protein. Chopping of the raw materials causes a temperature rise of the meat batter; therefore, the use of ice during formulation helps to ensure that the mixture is blended at 0–3 °C (32–37.4 °F). The remaining ice/water is added, followed by fatter meats (e.g., 80/20 or 50/50) and then binders, flours, and seasonings. The rationale for chopping lean meat with salt and water is that maximum solubilization of myofibrillar protein occurs at the higher ionic strength before ‘dilution’ by fatter meats and binders. This will help to prevent emulsion collapse or ‘shorting out’ resulting in fat caps, gelatine pockets, and a greasy surface on the cooked product. Reasons for the lack of functionality from the proteins may be due to poor quality meat (e.g., not enough lean meat protein, denatured protein from acidification, and too much collagen), addition of too small amounts of salt and phosphate, overchopping, and incorrect final batter temperatures. The batter is chopped until a specific end-point temperature is reached, which is dependent on the fat properties of the animal species used. To create a stable emulsion, the added fat must exist as small pieces or droplets so that the protein matrix can coat the surface of fat particles, thereby reducing surface tension; this occurs when the temperature of the batter is raised. Not all products contain meat from only one species; therefore, the end-point temperature of a batter containing a majority of pork should be between 10 (50) and 13 °C (~55 °F); for poultry, 2 (35.6) and 7 °C (~45 °F); and for beef, 13 (~55) and 21 °C (70 °F). Bowl choppers can be used to manufacture both coarse and finely comminuted cured meat products. When a very fine emulsion is desired, some sausage manufacturers pass the chopped meat through a separate emulsifier before stuffing. In such cases, the batter is processed in a silent cutter only to a temperature ranging between 2 (35.6) and 4 °C (39 °F). As it passes through the

emulsifier, the temperature goes up, and the emulsification step continues until the final end-point temperature of the product is achieved. In some emulsion-type products, vacuum chopping will increase the protein extraction and density of the emulsion. Vacuum chopping/stuffing removes most of the air from the emulsion and gives greater product uniformity, reduction in voids, better protein extraction, better color retention, and an increased shelf life. For example, in bologna, which is a largediameter product, vacuum chopping is desirable to eliminate air bubbles or pockets that could cause color fading and a soft texture to the final product. Binders or fillers are commonly used in the manufacturing of cured sausages and are normally made up of a combination of soy, cereals, as well as native and modified starches. If a product is high in meat protein and moisture but low in fat, then a high moisture-absorbing binder like starch can be employed. However, in a product with greater fat content, such as a frankfurter, a high protein binder like soy or milk solids might be chosen. Functional protein binders are binders where the protein has not been denatured during their manufacturing and thereby bestow properties to the meat matrix. The benefits of adding functional binders to a formulation include the following: increased protein level, improved texture, reduction in shrinkage, and overall juiciness and cohesiveness to the product. Once the batter is ready, it needs to be stuffed into a casing. There are special machines designed for this purpose. First, it is important that products be stuffed in casings to their proper diameter so that they resemble the product they are supposed to be. For example, one would not stuff the batter of a pepperoni stick into a salami casing and vice versa. In fact, frankfurters of a relatively large diameter casing, or in natural casings, are often referred to as wieners. Second, the product should not be under or overstuffed in the casing. Understuffing usually results in casings with wrinkles, whereas overstuffing can result in casing breakage during thermal processing. Most casing suppliers provide guidelines of recommended stuffing diameters for products and these take into account shrinkage after cooking. Finally, stuffed products are hung on trucks for thermal processing and smoking in an oven/smokehouse. Some meat plants are so sophisticated that they have continuous processing lines for frankfurter production. After thermal processing, the meat product is chilled, and when ready, it is peeled from its casing, packaged, and shipped to market.

Natural Nitrate- and Nitrite-Free Cured Meats Owing to the negative perceptions of nitrite-cured meats held by some consumers, there has been an interest of late in the ‘so-called’ nitrate/nitrite-free natural meat products. Any traditionally cured product produced in the US that does not include addition of a chemically derived form of nitrite is labeled as uncured. As previously discussed, nitrite/nitrate addition to meat products develops a characteristic color and flavor associated with cured meat products to which there is no known substitute. Without its addition, natural processed meat products would appear brown and their flavor would

Curing | Production Procedures Table 4

Formulation sheet for a natural hot dog

Product: Natural hot dog Ingredients

Level (%)

Quantity needed (kg)

Lean pork trim, 72/28 Beef trim, 50/50 Water Sea salt Natural hot dog seasoning Cane sugar, natural flavors, celery powder, onion powder, garlic powder, oleoresin paprika Starter culture

52.6 22.7 20.3 1.28 3.10

52.6 22.7 20.3 1.28 3.10

0.02

0.02

Note: Instructions: • Weigh out all ingredients and keep them separate. • Grind all chilled meats through a 0.19 in. plate, but keep meats separate from one another. • Mix starter culture with water totaling up to 0.50% of the total batch. • Mix/chop lean meats, adding in order, salt, half of the water, fatty meats, seasoning, and remaining water. • Add diluted starter culture. • Continue mixing/chopping until the meat blend temperature reaches 50−54 °F (10−12 °C). • Emulsify to 62−64 °F (17−18 °C). • Stuff and link. • Place on smokehouse rack and process using the smokehouse schedule: (1) 110 °F (~43 °C), 60 min; (2) 140 °F (60 °C), 20 min; (3) 155 °F (~68 °C), 30 min; (4) 175 °F (~79 °C), 30 min; and (5) 185 °F (85 °C)/30% RH to 165 °F (~74 °C) internal temperature. • Cold water shower to reduce internal temperature of product. • Transfer product to cooler, chill and when ready peel and vacuum package. Source: Reproduced from Sebranek, J. G., Bacus, J. N., 2007. Natural and organic cured meat products: Regulatory, manufacturing, marketing, quality and safety issues. White Paper Series Number 1. Savoy, IL: American Meat Science Association.

be appreciably less desirable to the consumer than those of conventionally cured counterparts. The USDA permits the manufacture of uncured versions of typical cured meats according to the Code of Federal Regulations Title 9, CFR 317.17 and 319.2. To circumvent nitrite regulation and labeling issues, natural curing is accomplished by employing sea salt and vegetable juice/concentrate/powder high in naturally occurring nitrates (e.g., celery has nitrate levels typically ranging from 1500 to 2800 ppm, whereas celery juice powder has been reported to contain ~27 500 ppm or 2.75% nitrate) in combination with a nitrate-reducing starter culture (e.g., Kocuria varians, Staphylococcus xylosus, and Staphylococcus carnosus) to ‘indirectly’ cure the product. Processors are using both preconverted nitrates (already converted to nitrite) from celery powder and unconverted celery powder with a starter culture that has a nitrate reductase enzyme to convert the nitrates into nitrite. This practice combined with labeling requirements for such products has resulted in a category of processed meats in the US that is confusing and perhaps even misleading to the consumer. Moreover, protection afforded by nitrite addition to meat products against spore germination of Clostridium botulinum is potentially compromised in these uncured products, because the conversion of nitrate present in celery

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into nitrite is not a well-controlled reaction. This raises the specter of the product's microbiological safety in vacuumpacked bags. For this reason, the USDA is also concerned about chilling rates on finished packaged products. If the processor is manufacturing a ‘naturally’ cured product, the residual nitrite level will more likely not be enough and a more restrictive chilling regime as outlined in Appendix B of the USDA meat regulations would be in order. For the most part, the processing procedures of natural curing are similar to those operations using sodium nitrite. Nitrate is more stable than nitrite; hence, a sufficient time is required to allow the starter culture to reduce exogenous nitrate to nitrite. The time needed depends on a number of factors including temperature, pH, growth cycle of the starter culture (i.e., number of microorganisms), and level of nitrate in the added celery powder. A good distribution of the ingredients is essential to ensure a uniform cure in such products. If dry, the vegetable powder (i.e., natural nitrate source) is typically blended into the dry seasonings for comminuted products or added directly to curing brines. The starter culture is often first mixed with water before addition to comminuted products and then dispersed via agitation for optimal distribution in the meat product. The USDA allows a maximum 0.5% combined water and starter culture without labeling the added water. The finished product, however, is required to bear a label disclaimer such as ‘no nitrates or nitrites added, except for that which occurs naturally in celery juice powder.’ A typical natural cooked sausage product formulation and process is given in Table 4.

See also: Bacon Production: Bacon; Wiltshire Sides. Chemical Analysis for Specific Components: Curing Agents. Curing: Brine Curing of Meat; Dry; Natural and Organic Cured Meat Products in the United States; Physiology of Nitric Oxide. Ham Production: Cooked Ham; Dry-Cured Ham. Processing Equipment: Brine Injectors; Mixing and Cutting Equipment; Tumblers and Massagers. Residues in Meat and Meat Products: Residues Associated with Meat Production

Further Reading Claus, J.R., Colby, J.-W., Flick, G.J., 1994. Processed meats/poultry/seafood. In: Kinsman, D.M., Kotula, A.W., Breidenstein, B.C. (Eds.), Muscle Foods. Meat, Poultry and Seafood Technology. New York, NY: Chapman & Hall, pp. 106–162. Ockerman, H.W., 1989. Sausage and Processed Meat Formulations. New York, NY: Van Nostrand Reinhold. Pearson, A.M., Gillett, T.A., 1999. Processed Meats, third ed. Gaithersburg, MD: Aspen Publishers, Inc. Pegg, R.B., Shahidi, F., 2000. Nitrite Curing of Meat. The N-nitrosamine Problem and Nitrite Alternatives. Trumbull, CT: Food & Nutrition Press, Inc. Romans, J.R., Costello, W.J., Carlson, W.C., Greaser, M.L., Jones, K.W., 2000. The Meat We Eat, fourteenth ed UpperSaddle River, NJ: Prentice Hall. Sebranek, J.G., Bacus, J.N., 2007. Natural and organic cured meat products: Regulatory, manufacturing, marketing, quality and safety issues. White Paper Series Number 1. Savoy, IL: American Meat Science Association. Sindelar, J.J., Cordray, J.C., Olson, D.G., Sebranek, J.G., Love, J.A., 2007. Investigating quality attributes and consumer acceptance of uncured, no-nitrate/ nitrite-added commercial hams, bacons, and frankfurters. Journal of Food Science 72, S551–S559.

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Sindelar, J.J., Terns, M.J., Meyn, E., Boles, J.A., 2010. Development of a method to manufacture uncured, no-nitrate/nitrite-added whole muscle jerky. Meat Science 86, 298–303. Toldrá, F., 2002. Dry-Cured Meat Products. Trumbull, CT: Food & Nutrition Press, Inc. Toldrá, F., Flores, M., Navarro, J.-L., Aristoy, M.-C., Flores, J., 1997. New developments in dry-cured ham. In: Spanier, A.M., Tamura, M., Okai, H.,

Mills, O. (Eds.), Chemistry of Novel Foods. Carol Stream, IL: Allured Publishing Corporation, pp. 259–272. Wakamatsu, J., Nishimura, T., Hattori, A., 2004. A Zn−porphyrin complex contributes to bright red color in Parma ham. Meat Science 67, 95–100.

CUTTING AND BONING

Contents Hot Boning of Meat Traditional

Hot Boning of Meat SJ James and C James, The Grimsby Institute of Further & Higher Education (GIFHE), North East Lincolnshire, UK r 2014 Elsevier Ltd. All rights reserved. This article is a revision of the previous edition article by AT Waylan, CL Kastner, volume 2, pp 606–614, © 2004 Elsevier Ltd.

Glossary Prerigor boning Process of removing meat from the bones of a meat carcass before the carcass has entered a rigor state.

Introduction Typically, meat is initially chilled after slaughter in the form of whole eviscerated and dressed carcasses or sides. The majority of carcasses/sides are chilled in conventional air chill rooms, nominally operating at one or sometimes two conditions during the chilling cycle. The rate of heat removal and the resulting rate of temperature reduction at the surface and within the carcass/side have a substantial influence on the weight loss, storage life, and eating quality of the meat produced. European Union regulations require that all red meat temperatures within the carcass/side must be reduced to not more than 7 1C before the meat is further processed, or moved from the chiller, whereas for poultry this temperature is 4 1C. Similar legislation is applied in many other parts of the world. Careful control is required to achieve conditions that will reduce the meat temperature in the designed time cycle. This has to be carried out in the most economic manner taking into account weight loss and energy consumption. The concept of deboning a ‘hot’ carcass was first mooted in the early 1970s. Potentially, the hot boning of carcasss has distinct advantages over cold boning. The warm meat is soft and requires less effort to bone, thus occupational overuse injuries are less likely to occur, there is potential for improved yield, and expensive chilling of fat and bones is avoided. There are also benefits in terms of certain processing qualities when hot-boned meat is used to manufacture meat products. However, there are also potential disadvantages of hot boning; for instance, the potential for the meat to be tough, darker in color, and for some primals to be different in shape.

Encyclopedia of Meat Sciences, Volume 1

Refrigeration May be defined as the process of removing heat from any substance to: (1) render colder – reduce temperature, (2) change its state – for example, water to ice, and (3) maintain its state – preserving foods, storing ice.

There is no strict definition of the temperature range over which boning can be considered as ‘hot.’ For example, in Australia, hot boning usually means boning carcasses that have a deep butt temperature of more than 20 1C. It is useful to consider hot boning in two categories – (1) ‘true’ hot boning and (2) warm boning. In true hot boning, carcasses or sides are not cooled before they are boned. They are boned within 30–45 min of slaughter. Plants that perform true hot boning often use plate freezers to cool the hot meat. Even with plate freezers, it can be difficult to rapidly reduce the temperature of large beef primal cuts. Bulk-packed product, at average temperatures of 28–30 1C, can normally be cooled in sufficiently rapid time using plate freezers. In warm boning, carcasss or sides are boned after a period of prechilling. Typically, carcasses are prechilled for 30 min to 6 h. Short prechills are used for lamb/sheep and longer periods for beef. Warm boning allows for an increase in throughput on the slaughter floor without having to increase chiller space. After warm boning, primals and manufacturing meat can be cooled quickly enough in air blast or plate freezers to prevent microbial growth.

Microbiology of Hot-Boned Meat A disadvantage of hot boning is that there is an increased risk that the meat can support the growth of pathogenic bacteria as it cools. In conventional boning, microbial growth on carcasss is controlled by a combination of drying and cooling of the carcass surface. When the meat is hot-boned and packed,

doi:10.1016/B978-0-12-384731-7.00235-X

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moist meat surfaces may be contaminated and provide an opportunity for microbial growth because they stay moist and warm. The surface temperature of boned meat prepared conventionally in accordance with regulatory requirements is usually less than 4 1C and the core of the meat below 7 1C. At these temperatures, the growth of pathogenic bacteria is stopped or is very slow. In the case of true hot-boned meat, the boneless meat surfaces could be 20–35 1C at the time of packing. At these temperatures, pathogenic bacteria can potentially adapt to their new environment within an hour or two and begin to grow quickly. Therefore, the meat must be cooled quickly to below 7 1C after it is hot boned in order to control the growth of pathogenic bacteria. Both New Zealand and Australia have performance criteria for the cooling of hot boned, boxed beef that are based on the growth of Escherichia coli calculated from temperature histories for the centers of boxes.

Quality of Hot Boned Meat Immediately postmortem, there are two related processes that affect meat-eating quality: (1) a fall in muscle pH and temperature and (2) shortening of the muscle. The combination of a very rapid fall in pH and slow cooling of the carcass can lead to heat or rigor shortening; whereas a slow fall in pH and rapid cooling can lead to cold shortening. Shortening is undesirable as it can cause moderate to severe toughness. A further important penalty of both cold and heat shortening is a reduction in the ability of the meat to tenderize during aging. Also, both may adversely affect functional properties of manufacturing meat. Because of the lack of skeletal restraint, these phenomena are more important with true hot boning than with warm or cold boning. Ideally to avoid shortening problems, the aim is to achieve an optimal rate of pH fall during rigor mortis and cooling. However, this is not readily achievable with true hot boning because of the varying cooling rates within a carton of meat. The application of an electrical current to the carcass on the slaughter floor accelerates pH decline. Electrical currents may be applied via electrical stunning, immobilization, hide-puller probes, or from conventional electrical stimulation (ES). The effects on the rate of pH fall are additive and lead to the early onset of rigor mortis. In some abattoirs where extra low voltage stimulation and downward hide pullers are used, beef sides have attained close to ultimate pH (5.5–6.0) within 60 min of stunning. ‘Overstimulation’ in this instance is undesirable as it can increase the risk of heat shortening, reduce the aging potential of the product, and in warm (and cold) boning can cause denaturation and paleness of slow cooling internal muscles. Meat that is taken from a carcass prerigor and promptly subjected to further processing has manufacturing advantages, such as better fat emulsifying and water-holding properties. However, hot-boned meat is usually chilled, or frozen, before it is used for manufacturing. If hot-boned meat cannot be processed immediately after slaughter it is possible to preserve its superior manufacturing properties by very rapid (i.e., cryogenic) freezing. The meat must be frozen while it is still in

the prerigor state and held at storage temperatures close to  18 1C. In fresh beef, or mutton, freezing must be completed within 6 h of slaughter. If the meat is thawed before use, however, biochemical changes take place rapidly, and most of the advantages of prerigor meat are lost. By adding at least 2% salt (sodium chloride) before freezing, or at the time of thawing (e.g., during chopping), the superior qualities of the prerigor meat can be retained after thawing. When minced thoroughly with the meat, 2% salt has been shown to preserve the water-binding power of fresh (unfrozen) prerigor meat for some days. Comminuted prerigor meat has a water-holding capacity similar to that of similarly treated postrigor meat to which polyphosphates have been added. In some countries, the use of phosphates and other nonmeat additives to improve water-holding capacity and fat emulsifying properties of manufactured meat products is either forbidden, or restricted. The addition of salt to prerigor boned meat before freezing is acceptable, however, as salt is included in the formulation of sausage meats. Therefore, there is an opportunity to better exploit the superiority of hot-boned meat for processed meat products. Removing muscles from the carcass soon after slaughter changes their normal state. Some muscles are normally stretched on the carcass and become free to shorten when released from their attachments to bones. Others, which usually cool slowly because they are enclosed by other muscles, may be cooled much faster. These differences will affect tenderness development and can cause muscles that are tender when cold boned (e.g., tenderloin) to be toughened when hot boned. With true hot boning, meat is still in the prerigor state at the time of boning even if electrical stunning, electrical immobilization, or ES has been used. This makes muscles susceptible to adverse temperature/pH combinations. Shortening is particularly likely. To overcome these problems systems such as the Pi-Vac Elasto-Pack system for the prerigor muscles have been developed. These stretch or constrain the muscle during chilling. The Pi-Vac Elasto-Pack system operates by stretching tubes of highly elastic films to the inside walls of a packaging chamber. After inserting the muscle into the chamber, the pressure is released, and the film returns to its original dimensions. The forces from the elastic film stop the diametrical muscle expansion, which would result from the longitudinal contraction of the muscle. It is claimed that it is possible to chill the meat rapidly without detrimental effects on tenderness and produce an attractive shape for cuts. Other systems having similar aims are Tendercut, Tenderstretch and SmartStretch™. Smartstretch™ uses external air pressure to stretch and reform hot-boned primals into a uniform size, using restraining packaging to ensure that the stretch is retained during rigor. The technique has been shown to improve the initial tenderness (0 days aged) of beef striploins from adult cattle, although no effect was found after a 2-week aging period. The treatment increased cooking losses, but had no influence on moisture losses in raw or frozen meat, or on meat color. With warm boning, many muscles from electrically stimulated carcasses are at least partly in rigor at the time of boning. In this case, muscles are less likely to be affected by adverse postboning temperature/pH combinations. As with

Cutting and Boning | Hot Boning of Meat cold boning, skeletal restraint minimizes the risk of the meat being affected by adverse temperature/pH combinations during carcass chilling. The color and retail display life of hot-boned primal cuts is generally equivalent to that of conventionally boned product. However, in cold boning some of the deeper beef muscles are often paler than the more superficial muscles because of their slower temperature fall and faster pH fall. Hot boning can mean that these cuts are cooled more rapidly leading to less denaturation, leading to darker meat and less two toning than in their cold-boned counterparts. Some studies have also reported a greater color stability in hot-boned steaks. In addition, some staining of the fat of primal cuts with blood from superficial blood vessels has been experienced in hot boning.

Hot and Warm Boning Operations Hot boning is generally considered to be easier than cold boning, but care needs to be taken when handling the cuts as they may be slippery in comparison. A major health and safety advantage with hot boning is that the problem of hard fat is not encountered. However, difficulty can be encountered in trimming fat from primal cuts. This can result in a fat thickness that is not up to specification and a less attractive cut. However, with the proper training and care, trimming can be done accurately. In objective studies carried out in the United States, strain gauges were fitted on knife handles to measure the effort required to hot-bone beef. It was claimed that 49% less effort was required to hot-bone beef sides compared with cold boning. In addition, it has been reported that a yield improvement of 1.5–2.0% is achievable with true hot boning compared with conventional boning. This increased yield is a combination of reduced evaporation losses and more efficient removal of meat from the bones. Studies have shown that hot boning reduces the time taken to bone out a beef side from 18 to 14 min. However, it can take some time for boners to become fully competent with hot boning, thus yield advantages may not be immediately obvious.

Beef The New Zealand meat industry has pioneered the application of hot boning with approximately 20% of beef production processed hot in 2006 with large plants processing up to 80 000 cattle per year. Historically, hot boning plants were used almost exclusively to process manufacturing beef from bulls and cows; however, it is now commonplace to process prime beef animals using hot boning procedures. Regular audits of product quality have demonstrated that eating quality and other quality attributes can match those of meat produced by more conventional cold boning procedures, as long as pH and temperature decline are effectively managed. In contrast it has been reported that Brazil, which is the leading beef export country in the world exporting 1635 million tons in 2011, makes no use of hot boning and only limited use of ES.

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Immersion chilling has been investigated to improve chilling rates of hot-boned beef cuts. The commercial process that has developed involves vacuum packing hot-boned meat and transferring the packaged cut to a system similar to the auger system used for poultry processing. ES accelerates the onset of rigor and can be used to minimize if not eliminate cold shortening induced toughness in hot-boned beef. However, studies on beef sides that were hot boned and chilled at  20 or 0 1C showed that the meat from beef chilled at  20 1C was tougher than cold-boned controls after 7 and 14 days of aging. Drip loss from meat chilled at  20 1C was also higher than that hot boned and chilled at 0 1C or cold boned. Studies have been carried out to determine the effects of hot boning, low voltage ES, and chilling temperature on the tenderness of bovine M. longissimus dorsi (LD) and M. semimembranosus (SM) muscles. Hot-boned muscles, which were not electrically stimulated had higher Warner Bratzler shear force (WBSF) values and shorter sarcomeres than cold-boned muscles. Under fast and slow chilling regimes WBSF values were lower in ES hot-boned LD and SM muscles at days 2, 7, and 14 postmortem than those not electrically stimulated muscles. Hot-boned muscles subjected to slow chilling had longer sarcomeres than those subjected to fast chilling. In hot-boned SM muscles, ES resulted in longer sarcomere lengths. However, ES did not have a significant effect on the sarcomere length of LD muscles. As indicated by WBSF values, all muscles tenderized during aging, including muscles, were ‘cold shortened.’

Lamb As may be expected there appears to have been limited interest or work carried out on the hot boning of lamb. The small size of the lamb carcass makes it amenable to quick chilling and lamb cuts are often sold with the bone in. Few of the advantages of hot boning, therefore, apply to lamb. Nevertheless hot boning of lamb has been proposed as a means to reduce energy costs. Hot boning of lamb has been shown not only to improve flavor and juiciness and decrease cooking loss but it also can reduce tenderness. In one study on hot boning of lamb after ES, carcasses were placed in a drying room for approximately 35 min with an average temperature of 8 1C to dry the surface of the carcass to limit bacterial growth before hot boning. Within 2 h of slaughter the hot-boned cuts were treated in a SmartStretch™ machine before chilling and aging. The results of the study were that, irrespective of treatments (aging, stretch, or stimulation), 100% of samples would have been acceptable after 0 days on display. However, after 24, 48, and 72 h on retail display, 72%, 86%, and 93% of the samples would be deemed unacceptable to consumers, respectively. Studies on the eating quality of commercially processed hot-boned sheep meat showed that all samples were tougher than the recommended threshold for table meat. Only 13.5% of the samples met the ‘good everyday’ requirement following sensory assessment. The authors reported that the application of effective ES is not sufficient to ensure that hot-boned sheep meat will be suitable as a table meat.

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Pork Although cold shortening can produce toughening in pork it is potentially less of a problem than in beef or lamb. Consequently a whole range of rapid chilling and warm/hot boning technologies have been developed for pork. As early as the 1950s, several progressive sausage manufacturers in the United States, who were also engaged in pig slaughtering, deboned hot (less than 1 h postmortem) sow carcasses. The resulting prerigor muscles were treated with salt or sometimes polyphosphates and this procedure improved the waterholding capacity for the production of frankfurters. Today, the majority of sows and some boars, 15% of the total pork production, are hot boned and nearly all the musculature transformed immediately into sausages. This is the most extreme example of accelerated processing currently in commercial operation, from pig to sausage in less than 2 h. The adenosine triphosphate present in prerigor pork acts as a natural glue in the production of restructured products and with the trend toward additive-free food, such processing prerigor bears reexamination. The rate of diffusion of salt through muscle becomes faster as muscle temperature rises. Also, the still intact arterial system of the pig immediately after slaughter provides a good distribution network for curing brine. Systems have been developed to hot cure bacon by arterially pumping cold brine into the carcass prerigor. This has the added advantage of partially cooling the meat, before immersion chilling in refrigerated brine. In a hot boning system developed in the late 1980s, loins were removed 30 min postmortem, vacuum packed, held in a water bath at 11 1C for 5 h, and then brine chilled. Drip loss after storage for 21 days at 0 1C was less (0.55%) than the control and other rapidly chilled treatments. Other sensory parameters were similar. In warm processing work, carried out at the same time, loins were removed from carcasses 1, 3, or 5 h poststunning. Three rapid cooling treatments; immersion in brine at  23 1C; CO2 chilling at  94 1C or packing in CO2 at  68 1C, were used in the trials. These produced loin temperatures of  2 1C after 1.5–2 h of chilling with no significant difference between treatments. The crust frozen loins were then tempered and mechanically portioned. Pork chilled at 1 h poststunning resulted in high shear force values and short sarcomere length. For a delay time of 3 h or more there were no major differences in muscle color, pH, sarcomere lengths, drip, or taste panel determinations between treatments and a conventionally (0–2 1C chiller) chilled control. Cold shortening in pork was first confirmed in trials where pork carcasses and sides were chilled immediately after slaughter using air below  30 1C and high air velocities. Further trials showed that ES before rapid chilling alleviated the toughening problems. Other trials have shown that the detrimental effects of accelerated boning on pork tenderness can be overcome with temperature conditioning at 14 1C and aging for 4 days postslaughter. Chilling of muscles at 0 1C following accelerated boning resulted in cold shortening as seen by the reduction in sarcomere length relative to muscles chilled at 14 or 21 1C. Furthermore, the reduced sarcomere length increased drip loss and produced pork of a darker color.

Warm boning as practiced in Denmark is another technology that allows same day processing and distribution. Immediately after dressing, chilling in air at  25 to  30 1C for approximately 80 min is commenced. This brings the surface temperature down to approximately  2 1C. It is therefore necessary to equilibrate the carcass for one or two hours before cutting and boning take place. The total chilling loss is approximately 0.6%. After boning the meat is either vacuum packed for storage and aging; wrapped, boxed and frozen, or cured and tumbled. Not all the heat is extracted during the short initial blast chilling operation and further cooling is required after cutting. Studies showed that there were no differences in the microbial and sensory qualities of the ‘warm’ processed pork compared with cold-boned controls. Overall yield was 0.8% higher than that from the controls. It is not uncommon in Spain for pork carcasses to be boned out after a 90 min chilling period. With the exception of the hams the rest of the carcass is immediately butchered into primals, which are further chilled and distributed on the same day as slaughter.

Horse Although little horse meat is eaten in comparison with other red meats, a considerable amount is produced. There is little data on either conventional or hot processing of horse; however, hot boning is likely to offer similar advantages and disadvantages as for beef. In one published study on the commercial warm boning of horse carcasses the cooling process for warm-boned meat met with standards for hot-boned beef cooling processes based on calculated growth of E. coli at box centers. In the plant studied, carcass sides were cooled overnight, or for between only 1 or 2 h. In the latter case, the warm carcasses are divided into quarters and prime cuts of meat removed from the hanging quarters placed directly into bags for vacuum-packaging followed by air blast chilling air at a temperature of  5 1C and a speed of approximately 4 m s1. For 80% of the temperature histories, the initial temperature was 420 1C and temperatures of 7 and 0 1C were attained within 13 and 26 h, respectively. Numbers of bacteria recovered from cooled carcasses or hot- or cold-boned cuts were generally similar. The microbiological condition of horse carcass quarters delivered to plants in Europe was claimed to be comparable with the microbiological conditions of hanging beef delivered from packing plants to distant customers within North America.

Poultry Production of deboned poultry meat has rapidly increased since the 1990s. Hot boning of poultry results in similar advantages and disadvantages as for red meat. However, the onset of rigor is far faster in poultry than red meat. As with red meat, ES is often used to speed the onset of rigor, allowing for hot boning without toughening. Electrical stunning at 40 V and high frequency is claimed to significantly improve the texture of chicken and can produce hot-boned breasts with acceptable tenderness. Boning is commonly carried out at

Cutting and Boning | Hot Boning of Meat 1.5–2 h postmortem. However, breasts are usually boned out after 24 h postmortem. There have been a number of studies on the eating quality of breast fillets boned at different intervals postmortem. Studies on the eating quality of cooked chicken fillets from either hot boned at 45 min postmortem or cold boned at 2 or 24 h postmortem showed little difference between hot and the 2 h boned fillets. However, the flavor profile of 24 h boned fillets was different from both hot and 2 h boned samples. The 24 h boned were rated less cardboardy and sweeter. In other studies on breasts boned from 0.25 h (hot boned) to 24 h all the meat produced before 6 h postmortem was judged to be tougher than that boned after 6 h or later.

Conclusion Hot boning of beef, pork, lamb, horse, and poultry carcasses offers a variety of benefits to the processor such as increased boning yield and savings in refrigeration capacity and energy usage compared with conventional cold-boning operations. In addition manufacturers of further-processed products have realized the improved functionality of hot-boned muscles especially in the production of ground beef and pork items. Common problems with early hot-boned meat systems usually included reduced tenderness, distortion of muscle shape, and darker lean color. However, the use of ES or muscle restraining and aging systems greatly reduces, or eliminates, many of these problems. Prerigor boning and chilling systems are applicable to the meat industry and provide a safe and high-quality product. Although a number of countries, such as New Zealand and Australia, have embraced the benefits of hot boning, the lack of understanding of, and information about, hot processing, the operational changes required to make hot-boning systems work in current operations, and fear of reduced shelf-life has limited the uptake of hot-boning in other countries, especially in Europe and the Americas.

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See also: Electrical Stimulation. Meat Marketing: Transport of Meat and Meat Products. Modeling in Meat Science: Refrigeration. Physical Measurements: Temperature Measurement. Refrigeration and Freezing Technology: Freezing and Product Quality; Thawing

Further Reading International Institute of Refrigeration, 1986. Recent advances and developments in the refrigeration of meat chilling. Proceedings of the Conference of: IIR Commission C2, Bristol (UK). Paris, France: International Institute of Refrigeration. International Institute of Refrigeration, 2001. Rapid cooling of food. Proceedings of the Conference of: IIR Commission C2, Bristol (UK). Paris, France: International Institute of Refrigeration. James, C., Vincent, C., de Andrade Lima, T.I., James, S.J., 2006. The primary chilling of poultry carcasses − A review. International Journal of Refrigeration 29 (6), 847–862. James, S.J., James, C., 2002. Meat Refrigeration. Cambridge, UK: Woodhead Publishing Limited. ISBN 1 85573 442 7. Kerry, J.P., Kerry, J.F., 2011. Processed Meats: Improving Safety, Nutrition and Quality. Cambridge, UK: Woodhead Publishing Ltd. Nollet, L.M.L., Toldrá, F., 2006. Advanced Technologies for Meat Processing. Boca Raton, FL: Taylor and Francis.

Relevant Websites http://www.ecff.net/ Official Site for the European Chilled Food Federation. http://www.fao.org/ Official Site for the Food and Agriculture Organization of the United Nations. http://www.iifiir.org/ Official Site for the International Institute of Refrigeration. http://www.chilledfood.org/ Official Site for the UK Chilled Food Association.

Traditional JW Savell, Texas A&M University, College Station, TX, USA r 2014 Elsevier Ltd. All rights reserved. This article is a revision of the previous edition article by RJ Davies, volume 1, pp 375–381, © 2004, Elsevier Ltd.

Glossary Fabricate (as related to meat cutting) To reduce a carcass into its major and minor components for further use in the retail and foodservice channels. Primal Large section of carcass usually associated with legs (e.g., round, leg, shoulder, chuck, rib, loin, etc.). Subprimal Sub-divided portion of primal into smaller pieces more suitable for portioning into steaks, roasts, or chops.

Introduction One of the challenges of communicating cutting and boning information to a worldwide audience is that the nomenclature and terminologies used vary so widely. Many technical references now feature pictorial examples of cuts so that a visual description can then be matched with the word description of it. It is always best to use anatomical descriptions – muscle and bone names – where possible so that the best and most universal description of carcass cutting/boning can be made. One such source is the International Committee on Veterinary Gross Anatomical Nomenclature, which provides detailed muscle and bone names. The scope of this article will focus on beef, pork, and lamb cutting and boning, but some of the methods and terminologies can be used for other livestock species of importance to some countries around the world. For the most part, prerigor cutting and boning is termed ‘hot processing’ or ‘hot boning,’ whereas postrigor cutting and boning usually is referred to as ‘cold processing’ or ‘cold boning.’ Because cold cutting/boning is the default method in the developed world, it may just simply be referred to as ‘cutting/boning’ because it is performed after chilling and limited cold storage. Cutting styles and nomenclature do not differ between hot or cold boning. The debate about the advantages and disadvantages of hot boning are numerous and will be discussed in the article on hot boning. Early humans probably developed crude cutting/boning procedures as they obtained carcasses from dead animals, through hunting or later through domestication and harvest. People had to find a way to handle the large carcass mass and reduce it into smaller pieces for possible sharing or for consumption over time, especially if performed during the winter months where cold temperatures would have allowed for extended storage for consumption at other times. Early cutting tools might have been made from stones before the advent of metal where various blade-type devices (e.g., axes and knives) would have been used to cut meat. The development of sawing tools would have assisted the carcass

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Superior spinous process The most dorsal portion of the vertebrae. Transverse process The lateral portions of the vertebrae most prominent in the lumbar area of the animal.

cutting process with band and reciprocating saws used commercially today. In fact, the thin blades of commercial band saws with the small amount of kerf they remove in the sawing process is of great economic importance for large-scale meat processors where even small savings in yields are magnified through the large volume of carcasses processed.

Terminology of Cutting and Boning Describing the process of converting carcasses into smaller portions is often confusing. For example, in the US, beef carcasses are ‘fabricated’ into wholesale cuts, using the broad definition of ‘fabricate’ i.e., ‘to make or build something.’ This term is usually shortened to state that ‘carcasses are being fabbed,’ or to describe the room where this process is conducted is simply referred to as the ‘fab room’ or ‘fab area.’ These are nonstandard uses of this term, but this simply demonstrates how terminology has evolved to describe various processes in the meat industry in at least one country. For the most part, pork is simply ‘cut’ so the description of the process and where the location of the process occurs is referred to as ‘pork cutting.’

Terms to Describe Wholesale Cuts of Meat Nomenclature used to describe the wholesale portions from carcasses varies from country to country, and also the nomenclature used to describe the general terms for what these portions are varies widely. The term ‘primal’ probably has its origin to the fact that a section of the carcass was a ‘prime’ or ‘primary’ region and thus this term was developed. Several decades ago, with the advent of widespread vacuum packaged, boxed meat programs, the term ‘subprimal’ began to be used because it best described smaller portions of primals. For example, the primal loin in beef could be further reduced to the strip loin, tenderloin, top sirloin, and bottom sirloin cuts. The trend today is for even further separation of cuts with some

Encyclopedia of Meat Sciences, Volume 1

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Cutting and Boning | Traditional now merchandized as an individual muscle (IM) with the term ‘IM’ being used in the names to signify such cuts. Because specific nomenclature and exacting specifications are necessary in buyer–seller relationships, and because the US Federal Government purchases a tremendous volume of meat for various buying programs, the Agricultural Marketing Service of the US Department of Agriculture (USDA) developed the Institutional Meat Purchase Specifications (IMPS) program as a way to have clear descriptions for the ever-evolving number of cuts available in the marketplace. The IMPS system also is used in market-news reporting as a way to note the prices being paid for specific cuts of meat. There are many different IMPS programs, but the ones related to this topic can be obtained from USDA for the categories of beef, pork, and lamb. In 1961, the National Association of Meat Purveyors (now known as the North American Meat Association) began publishing the ‘The Meat Buyer's Guides’ as a way to provide a pictorial depiction of these cuts. The scope of the guide has grown over the years to include beef, lamb, veal, pork, and poultry, and the guide has been published in a number of different languages to assist buyers and sellers in the world market for meat.

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Round

Rump

Sirloin Flank

Short loin

Short plate

Beef Carcass Cutting Rib

As mentioned earlier, methods of cutting/boning differ among countries and among companies even within a country. Beef carcass cutting is a method of cutting adapted from Savell and Smith, which reflects a US perspective of cutting/boning. Figure 1 depicts beef wholesale cut names used in this article. Beef sides are separated into forequarters and hindquarters based on historic precedence and whether the ribeye/loin eye is to be evaluated for a grading/classification system. In the US, carcasses are ribbed between the 12th and 13th rib for grading purposes. The exposed ribeye muscle (M. longissimus thoracis) is evaluated for the voluntary USDA quality grade program using human visual or video-image analysis systems. After grading and sorting by grade, weight, and other factors, sides are separated into forequarters and hindquarters by continuing the original ribbing cut through the plate/flank juncture perpendicular to the outside surface of the carcass. Before making this cut, the inside skirt (M. transverse abdominus) is loosened from its attachment in the flank area and dropped into the forequarter region so that it is not cut when separating the forequarter and hindquarter.

Brisket Chuck Foreshank

Figure 1 Beef wholesale cuts chart. Courtesy of the American Meat Science Association.

•

• Forequarter Cutting Here is a brief summary of forequarter cutting/boning that might involve table and on-the-rail methods, depending on facility layout and staffing.

• •

A knife cut is made between the 5th and 6th ribs through the lean and fat from the vertebrae to the sternum. The thoracic vertebra and sternum are sawn through between the 5th and 6th ribs to separate the chuck/brisket/ foreshank from the rib/plate section.

•

The rib is separated from the plate by cutting through the ribs at a point measured from the lateral edge of the ribeye muscle (M. longissimus thoracis) on each end of the rib. This distance should be no more than 15 cm from the ribeye muscle on the loin end (posterior) and no more than 25 cm on the chuck end (anterior). The foreshank and brisket are removed from the chuck just above the lateral condyle of the humerus by making the cut parallel to the top of the chuck. The foreshank and brisket are separated at the natural seam between them.

Forequarter Boning There are a number of major boneless subprimals that come from the forequarter. Here are a few and how they are prepared.

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Beef Rib Ribeye, Lip-On (IMPS 112A)

Beef Chuck, Chuck Roll (IMPS 116A)

This is the most common form of boneless ribeye marketed in the United States.

The scapula and M. supraspinatus are removed from the remaining portion of the arm chuck. The chuck portion is then separated from the foreshank before further processing.

•

•

•

•

•

The wholesale rib that is 15  25 cm (length of ribs from the lateral edge of the M. longissimus thoracis) is now cut so that the rib is 7.5 cm (measured from the lateral edge of the M. longissimus thoracis on the loin or posterior end)  10 cm (measured from the lateral edge of the M. longissimus thoracis on the chuck or anterior end). The body of the vertebral column is removed on a band saw exposing a strip of lean between the feather bones (superior spinous processes of the vertebral column) and the rib bones. The feather bones are removed. The blade meat (portions of M. subscapularis and M. rhomboideus immediately below, and M. latissimus dorsi, M. infraspinatus, and M. trapezius immediately above the scapula) is removed starting at the ventral end of the rib near the seam in the exterior fat cover and continuing up to the dorsal end of the rib. Remove the ligamentum nuchae and the portion of the ‘lip’ (consists of the M. serratus dorsalis, M. longissimus costarum and associated fat tissues) that exceeds 5 cm from either end of the rib so that the ribeye is 5 cm  5 cm. This ribeye is now a Beef Rib, Ribeye Roll, Lip-On, Bone In (Export Style), or IMPS 109E. Remove the back ribs beginning at the ventral end, being careful to follow the natural curvature of the ribs.

Beef Chuck, Shoulder (Clod) (IMPS 114) In industrial settings, the shoulder clod (major muscle system that contains the M. triceps brachii, M. infraspinatus, and M. teres major) is removed from the arm chuck, which is a chuck that has the foreshank still attached, but the brisket has been removed.

• • •

•

•

The arm chuck is suspended on-the-rail from the foreshank. A cut is made through the M. triceps brachii immediately below the elbow joint to the bone (humerus). The seam between the clod and the M. pectoralis profundus is opened. The M. triceps brachii is cut along the humerus to the knob portion of the bone (near the juncture of the humerus and scapula). At this point, the seam between the clod and the remaining portion of the chuck should be more evident. Continue cutting along the edge of the scapula paying particular attention to the complete removal of the M. infraspinatus from the scapula and the M. teres major from behind the scapula. The shoulder clod can be separated into these cuts: Beef Chuck, Shoulder (Clod), Top Blade (IMPS 114D), consisting of the M. infraspinatus; Beef Chuck, Shoulder Tender (IM) (IMPS 114F), consisting of the M. teres major; and Beef Chuck, Shoulder (Clod), Arm Roast (IMPS 114E), consisting primarily of the M. triceps brachii, caput longum (long head) and M. triceps brachii, caput laterale (lateral head).

•

• • •

Using a band saw, the neck is removed from the chuck by cutting through the 5th-6th cervical vertebrae and parallel to the cut that was made between the 5th and 6th ribs. Make a cut that is immediately ventral to the body of the vertebrae and parallel to the line where the brisket was removed to separate the chuck short ribs and the pectoral muscle (M. pectorales superficiales) from the chuck roll. Remove all feather or superior spinous processes, vertebrae, rib bones, and ligamentum nuchae from the chuck roll. Remove the M. trapezius and exposed seam fat from the outside surface of the chuck roll along with the prescapular lymph gland. The remaining arm portion shall be excluded by a straight cut that is not more than 7.5 cm ventral from the M. longissimus thoracis at the rib end (posterior) and not more than 10 cm from the M. complexus at the neck end (anterior).

Hindquarter Cutting

•

•

• •

Separate the loin/flank and round on a line between the 4th and 5th sacral vertebrae and approximately 2.5 cm anterior to the aitch bone. Cuts through the bone are made with a saw, whereas cuts through the lean are made with a knife. Remove the flank from the loin by making a cut no more than 15 cm from the lateral edge of the loin eye muscle (M. longissimus lumborum) at the rib end (anterior) to no more than 2.5 cm from the lateral edge of the M. tensor facia latae in the round end (posterior). There is one saw cut (13th rib) and the remainder is made with a knife. Remove the kidney knob and pelvic fat leaving no more than 1.3 cm of fat at any point. Separate the short loin from the sirloin by cutting between the last two lumbar vertebrae parallel to the sirloin face (posterior).

Hindquarter Boning There are a number of major boneless subprimals that come from the hindquarter. Here are a few and how they are prepared.

Beef Round, Sirloin Tip (Knuckle), Peeled (IMPS 167A)

•

•

On the table, remove the caudal vertebrae from the round along with the lean and fat tissue around the top of the aitch bone. Remove the aitch bone paying particular attention to staying very close to the bone. Hang the round from the rail by the hock. Begin removing the knuckle by cutting just posterior to the knee cap. Follow the seams between the knuckle and the

Cutting and Boning | Traditional

•

M. biceps femoris and M. adductor and along the femur making sure to remove the periosteum as the knuckle is removed. Remove the M. tensor fasciae latae, fat, and skin tissue to make this a ‘peeled’ knuckle.

Beef Round, Top (inside) (IMPS 168)

• •

• •

Make a knife cut beginning at the posterior section of the top round (M. semimembranosus and M. adductor are the major muscles) on the inside portion of the round. Continue removing the top round by following the natural seam and cutting along the femur. Finish removing the top round and trim external fat to purchaser’s specifications.

Beef Round, Outside Round (Flat) (IMPS 171B) and Beef Round, Eye of Round (IM) (IMPS 171C)

•

• •

These subprimals may be removed together as the Beef Round, Bottom (Gooseneck) (IMPS 170) before being separated into these two cuts.

• • • • • •

Make a knife cut immediately below the Achilles tendon being careful so that the hock will still be hanging on the hook. Continue the cut until the shank muscle seam is found. Remove the gooseneck round following the shank muscle seam and down along the femur. Remove the heel muscle from the gooseneck round. Separate the eye of round from the bottom round. Trim external fat from the eye of round to purchaser’s specifications. Remove the opaque heavy connective tissue (often referred to as ‘silver skin’), seam fat, lymph glands, and cartilage and ligaments. Trim external fat to purchaser’s specifications.

Beef Loin, Tenderloin, Full, Side Muscle On, Defatted (IMPS 189A), Beef Loin, Strip Loin, Boneless (IMPS 180), and Beef Loin, Top Sirloin Butt, Boneless (IMPS 184) These three subprimals are the major cuts obtained from the loin. To remove the full tenderloin, the loin has to remain intact and not separated into the sirloin/short loin sections as previously described.

Beef tenderloin

• • • •

•

From the full loin, remove the kidney and pelvic fat, being careful not to cut into the tenderloin. Remove the bottom sirloin flap and flank steak from the flank. Begin removing the tenderloin in the tail region by carefully cutting it from its attachment to the lumbar vertebrae. Continue cutting the tenderloin away from its attachment to the lumbar vertebrae by following along the body of the chine bones and the finger bones (transverse processes of the lumbar vertebrae). When the tenderloin is loosened near the sirloin/short loin juncture, begin removing it from the sirloin face (posterior).

Carefully roll out the tenderloin by cutting the attachment of the wing (M. iliacus) to the pelvic bone. Trim the remaining fat from the tenderloin being careful not to separate the chain (M. psoas minor) from the body of the tenderloin (M. psoas major).

Beef strip loin

• •

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•

Separate the shell loin from the sirloin by cutting between the last two lumbar vertebrate and parallel to the sirloin face (posterior). On the strip loin portion, using a band saw, cut the bodies of the vertebrae away so that there is clear separation between the superior spinous processes and the transverse processes. Using a knife, carefully remove the superior spinous processes, transverse processes, and the 13th rib from the strip loin. There are several purchaser-specified options that can be used for flank removal: a common one today is 2.5 cm  0 cm, which refers to making a straight cut at a point 2.5 cm on the rib end (anterior) to a point 0 cm on the sirloin end (posterior) ventral to the loin eye muscle (M. longissimus lumborum). Trim the external fat to purchaser’s specifications.

Beef top sirloin

•

• •

With the full sirloin, separate the bottom sirloin from the top sirloin using a knife and following the seam between the two. The bottom sirloin can be further separated into the Beef Loin, Bottom Sirloin Butt, Ball Tip, Boneless (IMPS 185B) and Beef Loin, Bottom Sirloin Butt, Trip-Tip, Boneless (IM) (IMPS 185C). For the top sirloin section, remove the hip bone and sacral vertebrae. Trim the external fat to purchaser's specifications.

Pork Carcass Cutting Here are general procedures for cutting pork carcasses, with Figure 2 depicting wholesale cut name and location. The loin/ ham break has some latitude and will vary based on the relative value of each of these cuts. When loin prices are higher than ham prices, the cut will be made closer to the ham; conversely, when ham prices are higher than loin prices, the cut will be made closer to the loin.

General Pork Carcass Cutting

•

•

The leg or fresh ham is separated from the pork side by making a straight cut approximately perpendicular to a line parallel to the shank bones and that passes through a point that is not less than 3.7 cm and not more than 8.8 cm from the anterior edge of the aitch bone. There shall be no more than two sacral vertebrae, but no caudal vertebrae left on the loin. The shoulder is separated from the side by a straight cut that is approximately perpendicular to the length of the side. The

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Hind foot

• • •

Pork leg

than 2.5 cm from the innermost curvature of the ear dip, then the neck bones, ribs, breast bones, associated cartilage, and breast flap (through the major crease) are removed. The skin, dorsal to a straight line parallel to the dorsal side that starts at a point that does not exceed 25% of the distance from the elbow joint to the dorsal side, is removed. Fat exposed by the removal of the skin is trimmed to not exceed 1.3 cm or more from the edge of the skin collar, and traces of false lean (M. trapezius) are to be visible. The picnic shoulder is separated from the Boston butt by making a straight cut, dorsal to the shoulder point approximately 1.3 cm from the dorsal edge of the blade bone on the loin side, at an approximate right angle with the belly side.

Pork Leg (Fresh Ham) Cutting

• Belly Loin

• • Spareribs

•

Picnic shoulder

Remove the tail, vertebrae, flank muscle (M. rectus abdominis), M. cutaneous trunci, prefemoral lymph gland, and any other exposed lymph nodes. Remove the foot at or slightly above the hock joint. The skin and collar fat over the cushion (M. semimembranosus) is removed so that it is smooth and well rounded such that the innermost curvature of the skin is trimmed back at least half the distance from the stifle join to the posterior edge of the aitch bone. The skin overlying the medial side (inside) of the M. quadriceps femoris and fat close to the lean overlying the M. quadriceps femoris and pelvic area are removed.

Boston Butt

Pork Loin Cutting Front foot

•

Jowl Figure 2 Pork wholesale cuts chart. Courtesy of the American Meat Science Association.

•

cut is made posterior to, so as not to expose, the elbow, but not more than 2.5 cm from the tip of the elbow. The outer tip of the M. subscapularis shall not extend past the dorsal edge of the base of the medial ridge of the blade bone. The belly is removed from the loin making a straight cut (a slight dorsal curvature is acceptable) that extends from a point that is ventral to, but not more than 7.5 cm from the M. longissimus thoracis on the shoulder end, to a point on the leg end ventral to, but not more than 1.3 cm from the tenderloin (M. psoas major).

Pork Shoulder Cutting

• •

The foot is removed at or slightly above the upper knee joint by making a straight cut approximately perpendicular to the shank bones. The jowl is removed by making a straight cut approximately parallel with the loin side that is anterior to, but not more

•

The surface fat of the loin is trimmed to an average of 0.6 cm or less in depth except in the hip bone area (defined as the area contained within two parallel lines, 5 cm on either side of the anterior end of the hip bone and associated cartilage). Fat in the hip bone area is trimmed to the same contour as the rest of the trimmed surface of the loin. Lumbar and pelvic fat are trimmed to 1.3 cm or less in depth. At least 5 cm of the false lean (M. trapezius) shall be exposed lengthwise on the blade end of the loin, and the diaphragm and hanging tender are removed.

Lamb Carcass Cutting Because of their size, lamb carcasses are not split in half during the slaughter-dressing process like beef and pork, so the style of fabrication differs somewhat from these species. Here are some general cutting procedures which Figure 3 depicts lamb wholesale cut name and location.

Carcass Primal Breaking

•

The foresaddle is separated from the hindsaddle at the 12th and 13th rib by a cut that follows the natural

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• Leg

•

• • Flank Loin

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(posterior) and through the cartilaginous juncture of the first rib. The neck is removed leaving no more than 2.5 cm of it on the shoulder. The thymus gland and heart fat is removed. If desired, the shoulder can be split into individual shoulders by making a saw cut through the vertebral column. The foreshank is separated from the brisket portion of the breast by cutting through the natural seam, which may contain a portion of the web muscle (M. pectoralis superficialis). The trotter or lower foreshank is removed at or above the knee joint. The rack is separated from the breast by making a straight cut no more than 10 cm from the lateral edge of the ribeye muscle (M. longissimus thoracis). The diaphragm and fat along the ventral side of the vertebrae of the rack are removed. If desired, the rack can be split into half racks by making a saw cut through the middle of the vertebral column. The breast can be made into ‘Denver Style’ ribs by removing the sternum and costal cartilages, fell membrane, M. cutaneous trunci, exterior fat cover, M. latissimus dorsi, and diaphragm.

Lamb Hindsaddle Component Cutting

•

Rack

Breast

• Foreshank

Neck

• •

Shoulder Figure 3 Lamb wholesale cuts chart. Courtesy of the American Meat Science Association.

•

•

curvature of the ribs. With this, there are 12 ribs that remain on the foresaddle and 1 rib on the hindsaddle. The foresaddle is separated into the shoulder/foreshank/ brisket portion of the breast and bracelet (rack and breast) by making a straight cut between the 4th and 5th ribs perpendicular to the back. This leaves four ribs in the shoulder and eight ribs in the rack. The hindsaddle is separated into the loin (with the flank attached) and the leg by making a straight cut, approximately perpendicular to the length of the leg, passing anterior to the hip bone and hip bone cartilage.

Lamb Foresaddle Component Cutting

•

The shoulder, square-cut is prepared by removing the foreshank and brisket portion of the breast by making a straight cut approximately perpendicular to the rack side

The flank is removed from the loin by making a straight cut no more than 10 cm from the lateral edge of the loin eye muscle (M. longissimus lumborum) on both ends of the loin. The diaphragm and hanging tender are removed from the loin. If desired, the loin can be made into half loins by making a saw cut through the vertebral column. The flank is separated into lean, fat, and bone (13th rib) portions. The legs are separated by making a saw cut through the vertebral column and pelvis. A short-cut leg can be made by removing the sirloin by making a straight cut approximately perpendicular to the length of the leg starting at the juncture of the last sacral and first caudal vertebra and passing just anterior to the protuberance of the femur (this exposes the ball of the femur). The short-cut leg can either have the tibia left in (French-style leg) or removed (American-style leg or shank-off leg).

Cutting and Boning Trends for the Future The widespread adoption of many of the cutting and boning schemes used around the world would not have happened without the development of plastic packaging technologies in the last part of the twentieth century. Vacuum packaging of fresh meats led to extensive and centralized cutting and boning near the point of slaughter, which allowed for innovative styles to be developed. In addition, with the advent of packaging technology, the ability to export meats to great distances and to countries that demanded specific cuts that might have never been used domestically greatly increased the development of new styles of cutting and boning. It is likely that these trends will only increase in the future.

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Further Reading

Relevant Websites

International Committee on Veterinary Gross Anatomical Nomenclature, 2005. Nomina anatomica veterinaria, fifth ed. Hannover, Germany: Editorial Committee; Columbia: Editorial Committee; Gent, Belgium: Editorial Committee; and Sapporo, Japan: Editorial Committee. Available at: http://www.wava-amav.org/ Downloads/nav_2005.pdf (accessed 08.01.10). North American Meat Processors Association, 2010. TheMeat Buyer's Guide™, sixth ed. Reston, VA: North American Meat Processors Association. Savell, J.W., Smith, G.C., 2009. Meat Science Laboratory Manual, eighth ed. Boston, MA: American Press. U.S. Department of Agriculture, 1996. Institutional Meat Purchase Specifications: For Fresh Lamb and Mutton − Series 200. Washington, DC: United States Department of Agriculture, Agricultural Marketing Service. Available at: http:// www.ams.usda.gov/AMSv1.0/getfile?dDocName=STELDEV3003283 (accessed 30.12.13). U.S. Department of Agriculture, 2010. Institutional Meat Purchase Specifications: Fresh Beef − Series 100. Washington, DC: United States Department of Agriculture, Agricultural Marketing Service. Available at: http://www.ams.usda. gov/AMSv1.0/getfiledDocName=STELDEV3003281 (accessed 30.12.13). U.S. Department of Agriculture, 2010. Institutional Meat Purchase Specifications: Fresh Pork − Series 400. Washington, DC: United States Department of Agriculture, Agricultural Marketing Service. Available at: http://www.ams.usda. gov/AMSv1.0/getfiledDocName=STELDEV3003285 (accessed 30.12.13).

http://www.ams.usda.gov Agricultural Marketing Service, United States Department of Agriculture. http://www.americanlamb.com American Lamb Board. http://www.meatami.com American Meat Institute. http://meatscience.org American Meat Science Association. http://www.fmi.org Food Marketing Institute. http://www.beefretail.org National Cattlemen’s Beef Association, Retail Marketing. http://www.pork.org National Pork Board. http://meatassociation.com North American Meat Association.

D DOUBLE-MUSCLED ANIMALS

S De Smet, Ghent University, Melle, Belgium r 2014 Elsevier Ltd. All rights reserved.

Glossary Callipyge A genetic mutation that causes lambs to develop large and muscular rumps, from the Greek for ‘beautiful buttocks.’ Double-muscled The exceptional muscular development as a result of a functional mutation in the myostatin gene. Heterozygous animals Animals having two different alleles of a given gene.

Introduction Double-muscled animals are of particular interest to meat producers because they are characterized by an increase in muscle mass and a decrease in fat deposition, resulting in a larger amount of lean meat than in normal animals. The term is mainly restricted to cattle and refers to an inherited condition that has been known for some time but of which the causal mutation in the myostatin gene was recently discovered. The condition is associated with altered physiological and histological characteristics that bring about differences not only in meat quantity but also in animal performance and in meat quality. Therefore, the use of double-muscled cattle in pure breeding or crossbreeding production systems has to be considered carefully, especially because of calving difficulties. Meat quality of double-muscled cattle differs from that of normal cattle in several respects and resembles as well as differs from meat of particular genotypes with enhanced muscularity in other species.

Genetic Background Double muscling is an inherited condition that occurs in several cattle breeds. However, it is highly prevalent in only two breeds, i.e., the Belgian Blue and the Piedmontese. Different symbols have been used to differentiate between the double-muscled and normal phenotype, of which mh

Encyclopedia of Meat Sciences, Volume 1

Homozygous animals Animals having the same alleles of a given gene. Muscular hypertrophy Exceptional muscular development. Myogenesis The formation of muscle tissue during development of an embryo. Myostatin A protein that acts as an inhibitor of the growth of muscle tissue.

(muscular hypertrophy) and + are the most common. The locus was mapped to the centromeric end of bovine chromosome 2. Identification of double-muscled animals was long based on visual assessment of the degree of muscular hypertrophy, i.e., by looking at protruding muscles and intermuscular grooves under the skin. This is only accurate in classifying normal and homozygous double-muscled animals, but does not allow distinction of heterozygous animals. This has contributed to the controversy in the early studies on the mode of inheritance of the mh allele. Segregation analyses later revealed that the mh allele was partially recessive with the mh/+ animals being distinct but closer to the +/+ than the mh/mh animals. In 1997, several research groups uncovered the genetic cause of double muscling by mutations in the myostatin gene. Myostatin (MSTN, also called growth and differentiation factor 8, GDF8) is a member of the transforming growth factor β superfamily of growth and differentiation factors. First, it was shown that mice in which the myostatin gene had been knocked out had a two to three times increased muscle mass (‘Mighty mice’). Because myostatin had been mapped before to the mh region of bovine chromosome 2, it was a very likely candidate gene for the mh locus. Sequencing of myostatin deoxyribonucleic acid from doublemuscled Belgian Blue cattle revealed an 11-bp deletion in the third exon causing a frameshift in the active C-terminal domain of the gene. Double-muscled Piedmontese cattle have a G to A transition also in the third exon, that changes a cysteine to a tyrosine in the same highly conserved region of the gene.

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Double-Muscled Animals

Later, four additional myostatin loss-of-function mutations were discovered, disproving the initial hypothesis that double muscling would be genetically homogenous and, originating from the Shorthorn breed was then spread from the British Isles to the continent and the rest of the world. Several mutations are shared by more than one breed. Most breeds examined are genetically homogenous, but several show allelic heterogeneity. The molecular dissection of this trait now also allows correct genotyping of animals, and thus a better comparison of the three myostatin genotypes for important traits, a shortcoming that many earlier studies suffered from. Naturally occurring functional mutations in the myostatin gene have further been described in humans, sheep, dogs, and horses, leading to similar hypermuscularity. In sheep, three different mutations have been reported so far. In the heavily muscled Texel breed, a single-nucleotide polymorphism in the 3´UTR of the gene was found that creates an illegitimate target site for two micro ribonucleic acids (miRNAs) that are highly expressed in skeletal muscle, causing a reduction in messenger RNA concentration and circulating myostatin protein levels, thereby contributing to the muscular hypertrophy. This hypomorphic allele segregates and causes an increase in muscle mass also in several other sheep breeds. No functional mutations in the myostatin gene have been discovered in other domestic farm animal species that have undergone intense selection for muscularity, such as pigs, poultry, and turkey. Only a putative mutation was found in the myostatin gene of Piétrain pigs, a breed that is also known for its heavily muscled phenotype. This fact could be fortuitous, but is likely indicating differences in myostatin physiology in different species. The finding that an allelic series of myostatin loss-offunction mutations explain most of the cases of double muscling in cattle, demonstrates the important function of myostatin in skeletal muscle. Active myostatin seems to play a key role in regulating myogenesis and acts as an inhibitor of muscle development. The inactivation of the protein causes an increase in the number of late myoblasts because of increased myoblast proliferation or delayed differentiation into primary and secondary myofibres. Myostatin appears to inhibit myoblast proliferation by arresting cell cycle at the G1-phase, and myoblast differentiation by downregulating the expression of differentiation related genes. Myostatin also maintains satellite cells in a quiescent state. The muscular hypertrophy of doublemuscled cattle is mainly the result of muscle cell hyperplasia, i.e., individual muscle fibers are not larger but higher in number, though some muscle fibers are indeed larger. Recently, it was shown that postnatal inactivation of the myostatin gene in skeletal muscle is able to cause a generalized muscular hypertrophy of the same magnitude as that observed for constitutive myostatin knockout mice, demonstrating that myostatin regulates muscle mass not only during early embryogenesis but also throughout development. The growth inhibition of proliferating skeletal muscle myoblasts by myostatin appears to be widely conserved among not only mammalian vertebrates but also avians and fish. The biological function of myostatin is, however, not restricted to suppressing skeletal muscle growth. Myostatin also appears to play a role in protein metabolism, and more specifically in the regulation of protein synthesis. It has also been shown to regulate glucose metabolism. The effects of

myostatin on adipose tissue are less well established, but it is clear that inhibiting its activity results in a large decrease of the fat mass. Myostatin is expressed at low levels in adipose tissue, and increases fat accumulation and adipogenesis. Although this may simply be a consequence of metabolic changes in skeletal muscle, it is likely that myostatin has a direct role in adipose tissue also and in the cross-talk between skeletal muscle and adipose tissue. The bioactivity of myostatin is not solely mediated by increased synthesis or release from skeletal muscle, but requires proteolytic cleavages of the precursor protein. The propeptide, as well as several other ligands, for example, follistatin and GASP-1, prevent receptor binding and activity of myostatin. Follistatin is a potent myostatin antagonist, and transgenic Mighty mice overexpressing follistatin have even greater muscle mass than follistatin transgenics alone. Once activated, myostatin appears to signal by directly binding to its serine/threonine kinase receptor. Downstream intracellular signaling pathways for myostatin are multiple and involve Smad-mediated and non-Smad pathways. As mentioned above, a role for miRNAs in the regulation of myostatin expression has become evident. Conversely, myostatin may regulate the expression of miRNAs. Evidently, muscle mass is under polygenic influence, and it should be stressed that as a result of ongoing selection, the muscular hypertrophy of the present-day Belgian Blue cattle is much more pronounced than the one of the mh/mh animals three decades ago. Similarly, there are large differences in muscularity between double-muscled animals of identical myostatin genotype from different breeds. However, it is unlikely that there are many other genes with comparable large effects on muscularity as the myostatin gene. The reason why myostatin null alleles, despite intense selection for improved carcass quality, still segregate at low or intermediate frequencies in most breeds tolerating double muscling, is that adverse side effects (see further) do not outweigh the tremendous benefits observed in lean meat yield from cattle possessing this mutation. Another gene with a major effect on muscularity is the callipyge gene in sheep located on chromosome 18, subject to a special mode of inheritance, i.e., polar overdominance. Similar to double-muscled cattle, callipyge lambs have improved feed efficiency and carcass quality, but because the callipyge condition manifests postnatally, dystocia is not a problem. Unlike double-muscled animals, callipyge sheep show muscle cell hypertrophy, and meat of callipyge lambs consistently has lower tenderness scores, resulting from a reduced degree of calpain-mediated postmortem proteolysis (see Section Carcass and Meat Quality). Pigs having the mutation in the ryanodine receptor gene on pig chromosome 6 leading to the stress susceptibility syndrome as a result of a disturbance in the Ca2+ transport of skeletal membranes have also improved carcass quality compared to normal pigs. The biological implications of this mutation are now well established, including large effects on meat quality, but the mechanism for the increased muscle mass, characterized by muscle cell hypertrophy, in stress-susceptible pigs is not elucidated yet. With the molecular genetics tools now being exploited, other genes affecting muscle development are likely to emerge, for example, the recently described regulatory mutation in the insulin-like growth factor II (IGF-II) locus in pigs with a major

Double-Muscled Animals

effect on carcass quality and without apparent effects on meat quality. The increased muscularity associated with these genes is associated with differences in animal physiology, in muscle fiber histology and biochemistry and consequently also in meat quality. Similarities but also distinct differences in meat quality compared to the effects of the myostatin gene are thereby observed.

Physiology and Metabolism Differences in circulating levels of various hormones and several other physiological parameters have been found in double-muscled compared to normal cattle, indicating an altered metabolism in favor of protein synthesis and lipolysis at the expense of lipid synthesis. The production of growth hormone is generally higher, whereas blood concentrations of insulin and IGF-I are normally lower. Concentrations of thyroid hormones are either not different or slightly lower. Small and mostly nonsignificant differences have been found for blood levels of cortisol, testosterone, glucose, α-amino nitrogen, and urea. Blood concentrations of triacylglycerols and nonesterified fatty acids have tendency to be lower and higher respectively. The blood level and urinary excretion of creatinine are clearly higher, in line with the higher muscle mass, whereas the opposite is the case for creatine. Other differences have been found too and it should be mentioned that the evolution of these parameters during development and growth, and the effect of management and nutrition conditions therein (e.g., compensatory growth) may differ at some points for double-muscled compared to normal animals. Though considerable variation is observed across muscles, double-muscled cattle possess nearly 25% more muscle mass than those cattle lacking the mutation. Conversely, there are sizable reductions (approximately 5–40%) in bone and fat masses as well as significant reductions in the digestive tract size (Table 1). The skin is thinner and external genitalia are less developed. Newborn calves frequently have an enlarged tongue (macroglossia). Normally this disappears at young age, creating only temporary problems when suckling. When persisting, grazing is disturbed in adults. Macroglossia is typical for double-muscled calves. Other congenital and/or inherited disorders are not restricted to double-muscled animals only, but are nevertheless seen more frequently in this kind of animals. Brachygnathia superior and brachygnathia inferior, i.e., an abnormal shortness of the maxilla (upper jaw) and mandible (lower jaw) respectively, and locomotory problems such as extreme flexing as well as extreme stretching of the fore and hind legs, spastic paresis, and other joint problems are common. Some of these disorders apparently do not harm the animal and may even disappear with age. However, locomotory problems may become problematic when gaining weight. Double-muscled animals up to 1 year are more vulnerable to respiratory diseases, increasing calf mortality. The likely reason therefore is the underdevelopment of the cardiorespiratory system. The lower respiratory capacity in combination with the increased muscle mass is also at the origin of the greater susceptibility to exercise fatigue and heat stress. Reduced oxygen transport, aerobic metabolic activity of the

Table 1 cattle

467

Effects of double muscling (myostatin loss-of-function) in

Double-muscled phenotype (mh/mh genotype) Meat production Fertility Calving difficulties Birth weight Daily weight gain Feed intake capacity Feed conversion efficiency Rusticity

 þþþ þþ 0  þ 

Carcass quality Dressing proportion Organ weights Carcass lean proportion Carcass fat proportion Carcass bone proportion Cutability

þ  þ   þ

Meat quality Muscle fiber hyperplasia Muscle fiber hypertrophy Color lightness Myoglobin content, oxidative metabolism Water-holding capacity Myofibrillar weakening, proteolysis Connective tissue content Tenderness (high connective tissue content muscles) Tenderness (low connective tissue content muscles) Juiciness and flavor intensity Intramuscular fat content

þ þ  þþ

þþþ 0 þ  0   þþ 0þ  

Note: The number of ‘ þ ’ or ‘  ’ indicates the degree of increase or decrease in double-muscle animals compared to normal animals, and ‘0’ indicates no major effect.

muscle, larger heat production, and lower capacity for heat dissipation all contribute to greater stress susceptibility. It has also been suggested that double-muscled animals have a more excitable temperament, but research data to support this are scarce and this statement can be questioned in view of the generally very docile temperament and the lower level of spontaneous activity of these animals experienced in commercial practice. Double-muscled cattle have reduced appetites and feed intakes compared to normal cattle as a result of the reduction of the size of the digestive tract (Table 1). Hence, they require adapted feeding systems for optimal or maximal production. When fed diets that meet their requirements, a more positive nitrogen balance and a reduced feed conversion ratio will be obtained. Urinary nitrogen excretion is significantly reduced, resulting in more efficient nitrogen retention. At the muscle protein level, the fractional rate of net synthesis appears similar, but the fractional rates of degradation and total synthesis are lower compared to normal animals. The rate of protein turnover, defined as the ratio of the fractional rates of net to total synthesis, is thus slower, explaining the higher efficiency of protein retention.

468

Double-Muscled Animals

Reproduction, Growth, and Management In general, fertility is reduced in double-muscled compared to normal cattle (Table 1). Sexual behavior is less distinct, making estrus detection more difficult for artificial insemination. Delays in puberty in heifers and males have been reported, but estrus characteristics and ovarian activity appear similar to normal animals. In males, testicular weight and semen volume and quality are reduced, but this poses little problem for reproduction. Reduced fertility in females is primarily manifested by a somewhat later age at first calving, longer intervals between calving and first estrus and between calving and first service, and a larger number of services per pregnancy. However, gestation length; rate of abortion; and incidence of placental retention, endometritis, and ovarian cysts are apparently not influenced. The most prominent difference with regard to reproduction is, however, the well documented higher frequency of calving difficulties (dystocia) due to a foeto-maternal morphological imbalance at calving. The higher birth weight and width of the calf especially at the trochanters in combination with reduced pelvic dimensions of the dam make delivery more difficult. Assistance on calving and ultimately cesarean section then become necessary in many cases. Part of the reduction in female fertility and rebreeding problems are associated with these calving difficulties. As expected, milk yield is substantially reduced in double-muscled cows. Birth weight of double-muscled calves is significantly higher compared to normal calves. Postnatal growth rate is not much different or is slightly lower. The combination of comparable average daily weight gain and lower feed intake results in significantly improved feed conversion efficiencies. The improved feed conversion is primarily due to the altered composition of body weight gain toward relatively more protein and less fat deposition, and likely not the result of changes in feed digestibility or maintenance requirements. Feed digestibility is only slightly affected or is decreased on high roughage diets. It is unclear at present if maintenance requirements are really lower in double-muscled animals. Data on total energy requirements during growth and development are also inconclusive, but feed protein requirements are obviously higher in view of the altered composition of weight gain. For finishing, double-muscled animals need high energy (concentrate) diets due to the lower feed intake, and their performance is reduced on high-fiber diets. More generally, they require higher skilled management and are less adapted to harsh environmental conditions. Animal performances are subject to the influence of many factors including breed, nutrition, and management. Hence, the effects of the double-muscled gene mentioned above may differ according to the breed, the ration, and the management conditions that are considered. However, it is clear that there are distinct differences for many traits that are either beneficial (efficiency of lean growth) or disadvantageous (reduced fertility and dystocia) to the overall production efficiency. The use of pure-breed double-muscled cattle in production systems around the world is limited, mainly because of the calving difficulties, and restricted to Europe where marketing systems favor high carcass yield. However, there is increasing interest for the use of double-muscled crossbreds in many beef

producing countries. There is a large variability in the performances of progeny from crossing double-muscled and normal cattle. The likely strategy is to cross double-muscled males with normal females, hereby reducing reproductive problems and maintaining a considerable part of the superior carcass characteristics. Although many of the problems associated with the double-muscling condition are not experienced in crossbreds, these systems still require pure-breed herds to be maintained. The need for routine cesarean sections in purebreeding systems is, however, sometimes also criticized on animal welfare grounds. More generally, the social acceptance of the use of extremely selected animals is expected to decrease in many societies. Hence, it is unclear at present if or to what extent double-muscled cattle will be utilized in the long term.

Carcass and Meat Quality The largest merit of double-muscled animals lies in their superior carcass characteristics (Table 1). Because of the slower rate of fat deposition, slaughter maturity is delayed. Inversely, animals of this genotype can be finished to higher slaughter weights. Dressing proportion is significantly increased (approximately 5%) compared to normal animals because of the reduced digestive tract and the lower weight of skin and organs. At similar age or weight, carcasses of double-muscled animals have higher proportions of lean meat and lower proportions of fat and bone. Although prominence is generally given to the muscle hypertrophy in describing the doublemuscled condition, the reduced development of the fat tissues is relatively much more distinct. The size but not the number of the fat cells is decreased. The reduction in bone proportion is more moderate. The muscle hypertrophy and the fat and bone hypotrophy are general but not uniform throughout the body. Especially superficial muscles and the hindlimbs compared to the forelimbs are most affected, but differences between studies as to the relative muscle hypertrophy are noticed. Bones of the limbs are shorter and thinner according to the same gradients observed for the muscles. The muscle to bone ratio is maximal at the level of the shoulders and the thigh where the hypertrophy is also most visible. At a comparable level of subcutaneous fat cover, a lower overall carcass fat content is found for double-muscled compared to normal animals. The nonuniform muscle hypertrophy and greater conformation in general results in a different size and shape of most meat cuts and in a higher proportion of more expensive cuts. In commercial practice, this effect of conformation and carcass cutability may add substantially to the difference in carcass value of double-muscled animals, irrespective of the difference in lean meat content. The combination of increases in dressing proportion, carcass lean content, and upgrading of some cuts may yield a difference in the proportion of high value cuts on a live weight basis that amounts to more than a quarter for pure-bred double-muscled compared to normal cattle. As mentioned above on the genetic determination, the myostatin-deficient condition leads to an increase in muscle fiber number (Table 1). The contractile differentiation during the first two-thirds of gestation and the metabolic differentiation of aerobic oxidative metabolism during the last third of

Double-Muscled Animals

fetal growth are delayed in double-muscled fetuses. A higher proportion of glycolytic muscle fibers at the expense of oxidative and oxido-glycolytic fibers are thus found at birth and throughout life in double-muscled cattle. Most reports indicate no major changes in the muscle fiber dimensions, and slightly lower as well as higher fiber sizes have been reported. Hence, the relative area of type IIB fibers is increased and the overall muscle metabolism is more glycolytic. The more glycolytic muscle fiber type results in a faster muscle pH fall postmortem in double-muscled animals, whereas ultimate pH values are generally not different. Concomitantly, the meat is paler, illustrated by higher CIE L⁎ values (Table 1). A lower ratio of CIE a⁎/b⁎ values corresponds to a less red color tint in line with reduced levels of myoglobin. The higher rate of glycolysis early postmortem, in combination with the increased muscle mass, also leads to slightly higher muscle temperatures postmortem, and consequently an increased degree of protein denaturation. This is expected to affect water-holding capacity unfavorably. However, data on several measures of water-holding capacity have been variable. Slightly higher drip and purge losses are generally found, but lower, unchanged as well as higher cooking losses have been reported. Differences in color and waterholding capacity in comparison with changes in other traits are relatively moderate. With respect to meat tenderness and palatability in general, literature concerning double-muscled cattle are coherent on most but not all points (Table 1). Meat tenderness and tenderisation are complex phenomena determined by a number of factors. The content and nature of connective tissue content together with the postmortem weakening of the myofibrillar and cytoskeletal network are considered the most important factors, provided that no extreme muscle shortening occurs during rigor development. No difference in sarcomere length in meat of double-muscled animals is observed under normal slaughtering conditions. A large reduction (approximately 25%) in muscle collagen content in double-muscled animals is reported in almost all studies. The perimysial connective tissue network is thinner, but the nature of the perimysial collagen in terms of solubility and crosslink concentrations on a collagen molar basis is not affected. The much lower content of connective tissue explains the upgrading of lower quality cuts to more expensive cuts, allowing for a larger and more homogenous distribution of high quality meat throughout the carcass. In muscles with a low content of connective tissue, like the Longissimus, the positive effect of double muscling on tenderness may be mitigated by reduced myofibrillar and cytoskeletal protein degradation that normally occurs during the tenderisation process. Double-muscled cattle have consistently lower µ-calpain, calpastatin, and cathepsin levels in the Longissimus, associated with changes in protein breakdown and in line with the reduced in vivo protein turnover. Total proteolysis and tenderization during full ageing seem to be lower in double-muscled animals. However, observations in the Longissimus indicate that proteolysis occurs at a faster rate early postmortem in double-muscled beef animals, consistent with the more glycolytic muscle fiber type and the earlier rigor development. Data for other muscles on enzyme activities and postmortem proteolysis are very scarce. The overall effect on shear force values is variable, depending on

469

the muscle studied and on the time/temperature treatment of the meat. Across studies and muscles, shear force values of raw meat have always been lower due to the lower collagen content. The literature shows that cooking meat for 1 h at 75 °C, the recommended standard preparation method for shear force determinations, yielded higher values for doublemuscled animals, but not in all studies. Because of extensive solubilization of collagen, this procedure of shear force determination can be regarded as a measure of myofibrillar toughness, but is not necessarily a good indication of overall tenderness. The higher myofibrillar toughness of doublemuscled animals as a result of reduced proteolysis is apparently only reflected in higher shear force values in heated low-collagen muscles in some studies. Indeed, taste panel tenderness evaluations on cooked meat do always show higher tenderness ratings, although the benefit may be lower for muscles low in connective tissue. Hence, in general meat from double-muscled animals is more tender. Meat of doublemuscled animals is particularly suited for raw consumption or after short time heating only, culinary preparation methods prevalent mainly in Western and Southern Europe. Regarding other taste panel parameters, lower juiciness, and beef flavor ratings have been reported, in line with the lower intramuscular fat content. The meat composition in double-muscled animals is changed according to the altered carcass composition. The meat protein content is higher and, because of the lower collagen content, protein quality in terms of essential amino acids content is improved. The intramuscular fat content is approximately 25% lower when compared to normal counterparts. Differences in fatty acid composition in different fat depots have also been reported. In intramuscular fat, the triacylglycerol content is greatly reduced as a result of the lower fat deposition, whereas the phospholipid content is only slightly lower in line with the lesser amount of cell membranes of the more glycolytic muscles. Accordingly, the contents of saturated and monounsaturated fatty acids are significantly reduced, whereas the contents of polyunsaturated fatty acids are similar or slightly reduced. Consequently, the molar proportions of polyunsaturated fatty acids are significantly higher and those of saturated and especially monounsaturated fatty acids are lower. The ratio of intramuscular polyunsaturated to saturated fatty acids is thus higher in meat from doublemuscled animals. Similar but less marked changes are to be expected in other fat depots. There are also indications for alterations in the n-6 and n-3 polyunsaturated fatty acid metabolism, based on differences in the proportions of the long chain fatty acids resulting from elongation and desaturation of linoleic and linolenic acid. The content of conjugated linoleic acids is similar relative to the sum of fatty acids, but is lower on muscle weight basis. Meat oxidative stability of doublemuscled and normal animals has not been properly compared at present, but there are no indications for large differences.

See also: Animal Breeding and Genetics: Traditional Animal Breeding. Chemical and Physical Characteristics of Meat: Chemical Composition; Palatability; Water-Holding Capacity. Classification of Carcasses: Beef Carcass Classification and

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Double-Muscled Animals

Grading. Connective Tissue: Structure, Function, and Influence on Meat Quality. Conversion of Muscle to Meat: Aging; Color and Texture Deviations; Glycolysis; Rigor Mortis, Cold, and Rigor Shortening. Growth of Meat Animals: Adipose Tissue Development; Endocrinology; Muscle; Physiology. Muscle Fiber Types and Meat Quality. Sensory and Meat Quality, Optimization of. Species of Meat Animals: Cattle. Tenderizing Mechanisms: Chemical; Enzymatic; Mechanical. Tenderness Measurement

Further Reading Arthur, P.F., 1995. Double-muscling in cattle: A review. Australian Journal of Agricultural Research 46, 1493–1515. Clinquart, A., Hornick, J.L., Van Eenaeme, C., Istasse, L., 1998. Influence du caractère culard sur la production et la qualité de la viande des bovins Blanc Bleu Belge. INRA Productions Animales 11, 285–297. De Smet, S., Claeys, E., Demeyer, D., 2002. Muscle enzymes in relation to meat quality and muscularity. In: Toldrá, F. (Ed.), Research Advances in the Quality of Meat and Meat Products. Kerala, India: Research Signpost, pp. 123–142. Fiems, L.O., Cottyn, B.G., Boucqué, Ch.V., et al., 1997. Effect of beef type, body weight and dietary protein content on voluntary feed intake, digestibility, blood and urine metabolites and nitrogen retention. Journal of Animal Physiology and Animal Nutrition 77, 1–9. Fiems, L.O., Van Hoof, J., Uytterhaegen, L., Boucqué, Ch.V., Demeyer, D., 1995. Comparative quality of meat from double-muscled and normal beef cattle. In: Ouali, A., Demeyer, D.I., Smulders, F.J.M. (Eds.), Expression of Tissue Proteinases and Regulation of Protein Degradation as Related to Meat Quality. Nijmegen: ECCEAMST/Audet Tijdschriften, pp. 381–393.

Gariépy, C., Seoane, J.R., Cloteau, C., Martin, J.F., Roy, G.L., 1999. The use of double-muscled cattle breeds in terminal crosses: Meat quality. Canadian Journal of Animal Sciences 79, 301–308. Georges, M., 2010. When less means more: Impact of myostatin in animal breeding. Immunology, Endocrine and Metabolic Agents in Medicinal Chemistry 10, 240–248. Grobet, L., Poncelet, D., Royo, L.J., et al., 1998. Molecular definition of an allelic series of mutations disrupting the myostatin function and causing doublemuscling in cattle. Mammalian Genome 9, 210–213. Hanset, R., Michaux, C., 1985. On the genetic determinism of muscular hypertrophy in the Belgian White and Blue cattle breed I. Experimental data. Genetics, Selection and Evolution 17, 359–368. King, J.W.B., Ménissier, F. (Eds.), 1982. Muscle Hypertrophy of Genetic Origin and its Use to Improve Beef Production. The Hague: Martinus Nijhoff Publishers. Raes, K., De Smet, S., Demeyer, D., 2001. Effect of double-muscling in Belgian Blue bulls on the intramuscular fatty acid composition with emphasis on conjugated linoleic acid and polyunsaturated fatty acids. Animal Science 73, 253–260. Rodgers, B.D., Garikipati, D.K., 2008. Clinical, agricultural, and evolutionary biology of myostatin: A comparative review. Endocrine Reviews 29, 513–534. Wheeler, T.L., Shackelford, S.D., Casas, E., Cundiff, L.V., Koohmaraie, M., 2001. The effects of Piedmontese inheritance and myostatin genotype on the palatability of longissimus thoracis, gluteus medius, semimembranosus, and biceps femoris. Journal of Animal Science 79, 3069–3074. Wray-Cahen, C.D., Kerr, D.E., Evock-Clover, C.M., Steele, N.C., 1998. Redefining body composition: Nutrients, hormones, and genes in meat production. Annual Reviews in Nutrition 18, 63–92.

Relevant Website www.ncbi.nlm.nih.gov/omia/1280 Online Mendelian Inheritance in Animals Database.

DRYING

PP Lewicki† J Arnau Arboix, P Gou Botó, J Comaposada Beringues, and I Muñoz Moreno, Institut de Recerca i Tecnologia Agroalimentèries (IRTA), Girona, Spain r 2014 Elsevier Ltd. All rights reserved. This article is a revision of the previous edition article by PP Lewicki, volume 1, pp 402–411, © 2004 Elsevier Ltd.

Glossary Effective water diffusion coefficient The amount of water (kg) that passes through a unit area (m2) in a unit of time (s) under the influence of a concentration gradient of one unit. Diffusion coefficient of water during drying of meat products depends on several factors such as temperature, water, and salt content. The SI unit of diffusion coefficient is (kg (m−2 s)−1). The value of this coefficient for diffusion of water in meat typically ranges from 10−10 to 10−11. Heat capacity The amount of heat required to raise the temperature of the material by 1 °C. The SI unit of heat capacity is J kgK−1. For nonprocessed meat values range approximately from 15 000 to 30 000. Quick-dry slice process (QDS process®) QDS process is an accelerated drying process for sliced meat products that is applied to the sliced product directly after the fermentation step before the long drying phase. This process results in a dramatically reduced total processing time. Thermal conductivity A meausure of the ability of a substance to transfer heat. The SI unit of thermal

Introduction Drying is a process in which water is removed from a material by evaporation, sublimation, or an osmotic process. Evaporated water is carried away by a stream of air, or it diffuses to an absorber or to a cold surface on which it is deposited as ice (frost) or water drops. Drying with the use of air is called convective drying, whereas diffusion of water molecules predominates in vacuum drying and freeze drying. Evaporation of water from the surface of the material being dried takes place at any temperature when there is a water activity gradient, but the higher the temperature the higher is the rate of drying, especially at the beginning of the process. The aim of drying is to increase the shelf life of the product and to create new, sometimes unusual, properties in the final product. Dry-cured ham, semidry, and dry sausages are good examples of controlled drying that imparts and develops special texture and flavor in the product. It is worth mentioning †

Deceased.

Encyclopedia of Meat Sciences, Volume 1

conductivity is (W mK−1). For nonprocessed meat values range from 0.1 for fat to 0.5 for lean. Vapour pressure of pure water (po) The pressure at which distilled water vapour is saturated at a given temperature. The SI unit of po is Pa. Vapour pressure of water in food (p) The pressure exerted by the water vapor in the foodstuff which is in equilibrium with the surrounding air. The SI unit of p is Pa. Water activity (aw) Water activity is defined (for practical purposes) as the ratio of the vapor pressure of water in a material (p) to the vapor pressure of pure water (po) at the same temperature. When vapor and temperature equilibrium are obtained, the water activity of the sample is equal to the relative humidity of air surrounding the sample in a sealed measurement chamber. Multiplication of water activity by 100 gives the equilibrium relative humidity (ERH) in percent aw ¼ p/po ¼ ERH (%)/100.

that sometimes drying is undesirable because of weight loss and an unpleasant appearance of the dry surface; freezer burn is an example. Drying is probably one of the oldest methods of food preservation. It takes advantage of the fact that only part of the water in food has the properties of bulk water, i.e., it is a good solvent and an environment in which biological reactions take place. Removing that part of water from food ensures its microbial stability and limits or inhibits chemical and enzymatic reactions. The state of water in food results from the structure of the water molecule and its interactions with the remaining food constituents. The phenomenon of interaction between water and solute molecules is termed hydration. The nature and extent of hydration shells surrounding the solute molecules depend on the kind of hydrated food constituent. Few water molecules surround ions and small molecules, whereas macromolecules such as proteins or polysaccharides can be hydrated by hundreds of water molecules. The properties of water in hydration shells differ from those of bulk water. Numerous experiments have shown that

doi:10.1016/B978-0-12-384731-7.00234-8

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Drying

part of water in food is so strongly associated with food constituents that it is not able to form crystals during freezing. The state of water in food is expressed by its activity coefficient, a measure of the thermodynamic chemical potential of water in the system. Under isobaric conditions and at temperatures typical for food processing (−20–120 °C), the properties of water vapor do not differ much from those of an ideal gas. Hence, the activity coefficient can be expressed as the ratio of the vapor pressure of water in food (p) to the vapor pressure of pure water (po) at the same temperature and total pressure. The activity coefficient is called the water activity (aw) and is expressed by the equation: aw ¼



p po P;T

The water activity of pure water is 1 and for absolutely dry material it equals 0. Fresh meat, in the lean portion, has aw ¼ 0.98–0.99. The water activity of meat products is dependent on the additives used and the processing applied. Sausages such as Bologna type, liver sausage, or blood sausage all have water activities in the range 0.93–0.98. Dry-cured ham has a water activity in the range 0.88–0.96, and the value depends strongly on the position within the ham and on the process used. Country-cured hams, ripened or dried for months, have much lower water activities than do raw hams subjected to a short ripening process. Fermented sausages usually have a similar range of water activity but, in some products, can reach a value as low as 0.72. Dried products usually have water activity below 0.7. Foods that have water activity from 0.60 to 0.90 and moisture between 10 and 40% are called intermediate-moisture foods (IMF). Such meat products as dry-cured ham, semidry and dry sausages, and cabanossi and salami all belong to the IMF classification. Drying is one method to reduce water activity in food. Evaporation of water removes mostly that portion of the water that has the properties of bulk water, i.e., water activity close to 1. Increasing the proportion of water associated in hydration

shells reduces the water activity of the food. The lower the water content, the lower the water activity of the food. However, the water activity and water content are not directly proportional (linear). The actual relationship at a given temperature is called a sorption isotherm (Figure 1). This enables one to predict the water activity of a given food at a prescribed water content. The sorption isotherm is characteristic for a given food, and its shape and course depends on the temperature, chemical composition, and structure of the material. Most foods have sigmoid isotherms, which means that at the low aw and high aw ends of the curve, large changes in water content are needed to change the water activity by a small fraction. In the middle, usually at water activities between 0.2 and 0.6, comparatively small changes in water content cause large changes in water activity. The sigmoid type of isotherm is typical of foods containing proteins and polysaccharides. Foods containing mostly small molecules, for example, sugar or acids, show isotherms that are concave downward. Drying as a method of reducing water activity in food can be assisted by the addition of substances that lower the water activity of the material. One of the effective depressors of water activity is sodium chloride (common salt, NaCl). At a concentration of 10% w/w, the water activity of the solution at 20 °C is 0.935; at 20% the water activity is 0.839. A saturated NaCl solution has a water activity of 0.755. Hence, by combining salting and drying, products with a sufficiently low water activity can be obtained without excessive dehydration. Good examples of products manufactured this way are charqui, an important meat product in rural Brazil; biltong, produced in South Africa; cecina, characteristic of the province of Leon in Spain; basturma (also known as pastirma), produced in many counties throughout the Caucasus, Balkans, and Middle East; and the traditional Cuban tasajo. All these products belong to the IMF classification.

Drying of Solid Foods The design and organization of food dehydration depends, in the first place, on the state and kind of material subjected to

Water content (g /100 g dry matter)

25

20

15

10

5

0 0

Figure 1 Water sorption isotherm of dried beef.

0.2

0.6 0.4 Water activity (aw)

0.8

1.0

Drying

drying. The state of the food, liquid or solid, determines the equipment, process design, and arrangement. Drying of solid food is a process in which water present within the microstructure of the solid is evaporated to the surrounding environment. During drying, two processes occur simultaneously: • Transfer of energy. • Transfer of water from the interior to the surface of the solid and its subsequent evaporation to the surrounding environment. Transfer of energy as heat occurs, in most cases, as a result of convection and conduction. In some cases, radiation is also used as a means of energy transfer. Using dielectric, radiofrequency, or microwave energy, heat is generated internally within the solid. In convective drying of solids, heat is transferred from the hot air to the surface of the solid. This process is dependent on air velocity and its temperature and humidity. The direction of air flow, the size and shape of the solid, and its degree of agitation also affect the rate of heat transfer. Heat transferred from the hot air to the surface of the solid is subsequently conveyed into the interior of the solid. In solid food, conduction is the prevailing mechanism of heat transfer within the solid. It depends on the difference between the temperature of the surface of the solid and the temperature of the coldest point within the solid, on the structure of the solid (its porosity), and on its thermophysical properties (heat capacity and thermal conductivity). In fibrous foods, the direction of heat flow in relation to the orientation of the fibers (parallel or perpendicular) is also important. Heat transfer in the drying of solids involves two processes: external and internal movement of heat (Figure 2). Hence, two sources of resistances to heat transfer operate: external and internal; these are also referred to as resistance to convective and to conductive heat transfer, respectively. Resistance to conductive heat transfer is usually larger than that for convective heat transfer and is strongly dependent on the water content in the solid. The lower the water content, the larger is the internal resistance to conductive heat movement. As a result, heat transfer within the solid during the final stages of drying is more difficult than at the beginning of the drying process.

Air stream Convection

Water vapour

Heat

Conduction

Diffusion

Solid food Figure 2 Heat and mass transfer during solid food drying.

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The relationship between external and internal heat transfer resistances is important for the quality of the dried product and course of the drying process. A large external heat flux (due to a large difference between the hot air temperature and the temperature of the surface of the solid) sometimes cannot be conveyed within the solid at a sufficiently high rate. In this case, the surface of the solid absorbs most of the energy, water is evaporated rapidly, and a dry layer that is less permeable to water is formed on the surface of the solid. Further evaporation of water is slowed down; drying is reduced and overheating and scorching of the surface can occur. In some drying methods, heat is supplied to the solid by conduction, which requires very good contact between the surface of the solid and the surface of the heating plate. Hence, this means of heat transfer can be used for drying paste-like materials, which can be spread on to the heating surface, or materials formed (cut) as parallelepipeds. Being in contact with the heating plate, the surface is excluded from the water evaporation process. Transport of water in the solid being dried proceeds again in two steps (Figure 2). First, water is transported from the interior to the surface of the solid. Different mechanisms for water movement within the solid are applicable, but diffusion and capillary flow prevail in foods; capillary flow occurs only in porous bodies. Second, water is evaporated at the surface of the solid and is transferred as vapor to the surrounding air. This process is a convective mass transfer. Hence, two resistances to transport of water operate during the drying of solids: internal and external mass transfer resistances. The internal mass transfer resistance depends on the effective water diffusion coefficient (which accounts for all possible mechanisms of water transport in the solid) and the temperature of the solid. In moist foods, the effective water diffusion coefficient is weakly dependent on water content and is assumed constant. However, at low water contents (below 20–30% w/w) the dependence of the effective water diffusion coefficient on the water content is very strong. A decrease in water content by a few percentage points can lower the effective diffusion coefficient by two or three orders of magnitude. The external mass transfer resistance depends on the same variables that are responsible for convective heat transfer. The relationship between external and internal mass transfer resistances affects the course of drying. If the external resistance is larger than or equal to the internal resistance, the flux of water reaching the surface of the solid is constant and drying proceeds at a constant rate. Drying at a constant rate can occur with very moist foods (e.g., some vegetables and fruits) but usually does not occur when the initial water content in a material undergoing drying is below 70–80%. If the internal resistance is larger than the external, less and less water is transported to the surface of the solid. The flux of evaporated water decreases with time and the drying proceeds at a falling rate. The course of drying can be presented as the rate of drying curve (Figure 3), and the transition from the constant to the falling rate of drying occurs at the critical moisture content. The mechanism of solids drying presented above shows that drying is a simultaneous process of heat and mass transfer in which four resistances occur. In general, internal mass transfer resistance is the most important factor and determines the rate of drying and time the process takes. There are ways to

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Drying

Air inlet 1

B

Rate of drying

C

Exhaust air

2

3

A

D ue

uc Water content

4

u0

Figure 3 Rate of drying curve for moist food. AB, initiation of drying; BC, period of constant rate of drying; CD, period of falling rate of drying; uo, initial water content; uc, critical water content; ue, equilibrium water content. Reproduced with permission from Lewicki, P.P. (Ed.), 1999. Inzynieria Procesowa I Aparatura Przemyslu Spozywczego (Food Processing Engineering and Food Processing Equipment). Warsaw, Poland: Wydawnictwa Naukowo-Techniczne, © 1999 Wydawnictwa Naukowo-Techniczne.

affect the internal resistance to mass transfer and to take advantage of an increased value in designing the drying process. The internal resistance to mass transfer can be modified by the predrying treatment of raw material, by its size and shape, and by the variables of the drying process. Predrying treatments include mincing, heating, cooking, freezing, and thawing. Mincing destroys internal microstructure, breaks cell walls and cell membranes, and releases the liquid phase. Minced material forms a capillary porous body in which cavities are filled with liquid, which can easily be transported to the surface for evaporation. Heating and cooking of food causes denaturation of proteins. In effect, cell membranes lose their semipermeable properties, and water movement in the tissue becomes easier. Moreover, denatured proteins are hydrated to a lesser extent than native ones and hence some water is released from the hydration shells. Freezing, especially slow freezing, leads to the formation of large ice crystals, which injure the tissue. Subsequent thawing yields material with destroyed or degraded microstructure, and the drying properties of the material become similar to those of minced material. The size and shape of the solid are also important. Transport of water from the wet center to the surface is dependent on the concentration gradient (the difference in water concentrations divided by distance). The larger the concentration gradient, the larger is the water flux. Because the concentration gradient is inversely related to the distance over which the water is transported, the water flux or the rate of drying is smaller for larger pieces of food. The shape of the solid also affects the drying rate. For the same distance of water transport, a long cylinder dries twice as fast, and a sphere three

Figure 4 Cabinet dryer: 1, heater; 2, recirculation damper; 3, trolley with shelves; 4, baffles. Reproduced with permission from Lewicki, P.P. (Ed.), 1999. Inzynieria Procesowa I Aparatura Przemyslu Spozywczego (Food Processing Engineering and Food Processing Equipment). Warsaw, Poland: Wydawnictwa Naukowo-Techniczne, © 1999 Wydawnictwa Naukowo-Techniczne.

times as fast as a plate (slab). The numbers are theoretically derived, but in practice a sphere always dries more rapidly than a cylinder and a cylinder loses water more rapidly than a plate. Temperature, air velocity, and humidity are important variables of the drying process. Transport of water is faster at higher solid temperatures. Hence, increasing the air temperature causes faster drying. The velocity of the air affects external heat and mass transfer resistances; increased velocity reduces the resistances. However, high air temperature and velocity can lead to rapid evaporation of water from the surface and formation of a crust. The humidity of the air affects the external mass transfer of water; high humidity causes slow drying and prevents crust formation on the surface of the solid. In some processes, the drying air is specially humidified in order to slow down the rate of water evaporation. Solids can be dried in a variety of types of dryers, but drying of meat and meat products can only be done in certain dehydrators: cabinet dryers, belt dryers, and vacuum tray or rotary dryers.

Cabinet Dryers A cabinet dryer (Figure 4) is built as an insulated chamber with trays stacked one above another on which material is loaded. The trays may be arranged onto trolleys or may be stacked individually into the slots of the cabinet. Air, forced by a fan, passes through the heater and is then baffled parallel to or across the trays loaded with the product. The flow of air through the layers of the product creates better conditions for

Drying

heat and mass transport. Cabinet dryers can be equipped with a recirculation damper, which makes it possible to take part of the exhaust air, mix it with fresh air, and use the mixture as a drying medium. This not only saves energy but also primarily increases the humidity of the air and prevents case hardening and crust formation on the surface of the solid. Cabinet dryers are batch dryers that are relatively easy to set and control the optimum conditions of the process. They are thus good for drying heat-sensitive materials.

Belt Dryers A belt dryer is suitable for drying small pieces of cut food. It comprises a long, rectangular drying chamber through which a finely woven wire mesh moves on rollers (Figure 5). Air is supplied from the bottom of the belt and can be recirculated. The speed of the belt is low and can be regulated over a broad range. At a speed of 0.1 m min−1 with a drying section 45 m in length, the residence time of the material undergoing drying is 7.5 h. This drying time can be too short for large pieces of food. In this case the belt dryer is used to remove most of the water from the material and final drying is done in another type of dryer, the bin dryer. The bin dryer is a container with a wire mesh bottom in which partly dried material is placed in a thick layer. Air is forced through the layer, and water evaporates until the required moisture content of the material is reached. Belt dryers have large yields and can be used in large-scale production. Some products can stick to the belt and can be difficult to remove at the discharge end of the dryer. A long drying section can be divided into sections in which the temperature of the air can be adjusted according to the heat sensitivity of the material being dried.

Vacuum Dryers Rapid drying under atmospheric pressure requires temperatures as high as 70 °C and large volumes of air in contact with the product. This affects quality disadvantageously. To lower

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the drying temperature and eliminate contact with the air, drying under vacuum can be applied. In vacuum dryers, heat is supplied by conduction and external mass transfer resistance is much larger than that in convection dryers. Hence, drying is a long process, but the quality of the final product is superior to that obtained in convection dryers. Vacuum cabinet dryers are designed as hermetically insulated chambers in which solid trays are heated by circulating a suitable heating medium. Contact between the food and tray surface is very important as well as the amount of food loaded on the tray. Product sticking to the tray surface can create a problem with emptying and cleaning the dryer. The vacuum rotary dryer is a stationary, jacketed, cylindrical shell, mounted horizontally with a revolving center tube on which a set of paddle arms with blades is mounted (Figure 6). The heating medium is delivered to the jacket, hollow center tube, and paddle arms. Solid pieces of food are loaded into the cylinder, the vacuum is pulled down, and stirring or agitation is initiated by rotating the center tube. Mixing the material prevents sticking to the heating surface, exposes the material's surface to evaporation, and facilitates heat transfer by conduction. Vacuum rotary dryers are batch dryers; they provide good control of the process parameters and the rate of drying is faster than that in vacuum cabinet dryers.

Freeze Dryers Freeze drying is another method of drying under vacuum. However, in this case the food is frozen before drying and drying parameters are below the triple point of water (Figure 7). Pure water can exist in all three phases – as gas (vapor), liquid, and solid (ice). The triple point is that combination of pressure and temperature at which all three phases are in equilibrium and can coexist. When the parameters are above the triple point, the change from solid to vapor must go through the liquid phase: hence the melting of solid occurs. When temperature and pressure are kept below the triple point values, sublimation occurs and a direct change of ice to vapor

2

1

3

5

4 Figure 5 Belt dryer: 1, feed; 2, exhaust air chimney; 3, fresh air inlet; 4, heater; 5, dry product outlet. Reproduced with permission from Lewicki, P.P. (Ed.), 1999. Inzynieria Procesowa I Aparatura Przemyslu Spozywczego (Food Processing Engineering and Food Processing Equipment). Warsaw, Poland: Wydawnictwa Naukowo-Techniczne, © 1999 Wydawnictwa Naukowo-Techniczne.

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Drying

4 3 2

1

Steam

Condensate

Condensate

Steam

5

Figure 6 Vacuum rotary dryer: 1, jacketed cylinder; 2, paddles; 3, feed; 4, connection to vacuum pump and condenser; 5, dry product outlet.

Pressure (Pa)

3

Ice

Water 2

Melting evaporation

1

Vapour

610.483 Pa Sublimation

0.0099 °C

5

Temperature (°C) Figure 7 Pressure–temperature phase diagram for pure water.

takes place. Because the water vapor pressure over food is lower than over ice, the pressure in a freeze dryer must be kept well below 610 Pa; it is usually 200 Pa or below. The temperature of the material is also kept well below the freezing point of the food; usually it is below −10 °C. Before the freeze drying process, the food is frozen in auxiliary equipment and then loaded to the freeze dryer. Freezing is a very important process and strongly affects both the sublimation process and the quality of the freeze-dried product. The larger the ice crystals and, in consequence, the more injured the tissue, the easier will be the transport of water vapor through the dry porous tissue, leading to a relatively short freeze drying period. However, the adverse influences of slow freezing on food quality are well known and, in designing the freeze drying process, a compromise must be made between process time and the quality of the product. A freeze dryer (Figure 8) is usually built as a cabinet dryer equipped with shelves heated electrically (for small-scale production) or with circulating hot mineral oil. Frozen product is loaded onto shelves, vacuum is pulled down to the required value, and controlled heating is started. The heating is controlled in such a way that the product never reaches a

4 Figure 8 Freeze dryer: 1, drying chamber; 2, heated shelves; 3, product; 4, condenser (resubliming surface); 5, connection to vacuum pump.

temperature at which melting would occur. Water vapor sublimed from the product is resublimed (i.e., it forms ice) on the condenser, whose temperature is well below the sublimation temperature (−40 to −50 °C). Heat and mass transfers in freeze drying are hampered by large internal and external resistances. Heat is conducted through the frozen layer to the zone of ice sublimation, whereas water vapor must pass the already dry layer and reach the condenser by diffusion. Large resistances are responsible for long freeze drying times, which are several hours and may exceed 24 h. Freeze-dried products are superior in quality to those dried under atmospheric pressure. However, freeze drying is the most expensive method of drying because of very low pressure, the freezing of the food, and long process time.

Drying

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Figure 9 Drying room for fermented sausages.

Meat mixture Stuffing 48 h

24 h

30 min

Fermentation

Freezing

Traditional drying

Slicing

Slicing

48 h

Figure 11 Quick-dry slice process facility for sliced fermented sausages.

4 weeks

temperatures ranging from 3 °C to room temperature. During that time 30–40% of initial weight is lost and the water activity of the product (especially on the surface) decreases sufficiently to prevent microbial spoilage. Circulating air is changed 15–50 times per hour. Drying of sausages depends on their variety and the diameter of the product. Stuffed sausages are first fermented by lactic acid bacteria and then hung in a drying room with air relative humidity of approximately 80%. The sausage loses some water but case hardening is avoided. In some cases, the air temperature is lowered to approximately 10 °C and the relative humidity to 70%. The air is circulated by a fan dimensioned to move from 15 to 75 times the chamber volume per hour. The process continues for 15–60 days, and the sausages lose 25–50% of their original weight. The growth of inoculated molds on the surface of sausages can be promoted by controlling the air's humidity and temperature to produce special types of sausages. Addition of glucono-δ-lactone to the batter of raw fermented sausage (salami type) strongly accelerates the acidification of sausage chubs and thereby substantially shortens the period of ripening. Recently, a new drying-maturing process, quick-dry slice (QDS), has been proposed for sliced products (Figures 10 and 11). Sausages are fermented to the desired pH and are then frozen, sliced, and dried in a continuous system that combines

Drying ‘QDS process’

Packaging MAP − vacuum Figure 10 Comparison between traditional and Quick-dry slice process for sliced fermented sausages.

Traditional Meat-Drying Facilities Some traditional meat products such as dry-cured ham, semidry, and dry sausages are obtained by removing a certain amount of water from the material by evaporation. This is a drying process, but it is done under specific conditions in drying rooms (Figure 9). The design of a drying room makes it possible to control temperature, humidity, and air flow. Usually the air circulates in the room, and this can be achieved by natural or forced convection. Drying of dry-cured ham is done at increasing

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Drying Drops formed by a rotating wheel atomizer are 20–250 mm in diameter. The area for evaporation is large and drying takes a few seconds. Rapid evaporation maintains a low droplet temperature. Hence, high drying air temperatures can be applied, in the range of 150–200 °C. Particles leaving the drying chamber have temperatures between 70 and 90 °C. The drying chamber is a cylinder with a conical bottom in which the spray makes contact with the hot air. The most common design is a concurrent system in which the droplets fall down the chamber with the air flowing in the same direction. Circulation of air in the drying chamber and trajectories of the particles undergoing drying should prevent the deposition of wet particles on the chamber wall. The dry powder is collected at the bottom of the drying chamber. It can be removed together with the exhaust air and product in the powder/air separation system. Commonly, the exhaust air is removed at some height above the bottom of the drying chamber. The product then accumulates at the bottom of the chamber and is discharged by means of a valve. Exhaust air carries only the fine particles, which are separated from the gas stream in the separation system. Separation systems consist of cyclones though, in some cases, bag filters are used. In cyclones, particles with a diameter larger than 15 mm are removed with high efficiency. Bag filters remove particles with diameter larger than 2 mm. Because of low product temperature and short drying time, spray drying is suitable for the drying of heat-sensitive products. However, economic spray drying can be done only with large-scale production. Meat extracts and purées can be dried by a spray drying technique. One product commonly manufactured by spray drying is dried blood plasma. This is concentrated by evaporation and is then fed to a spray dryer. The inlet temperature of the hot air is between 120 and 190 °C, but the outlet temperature should not exceed 70 °C. The drying time is very short and ranges from 2 to 4 s. The moisture content of dried blood plasma is between 5 and 8%.

both convective and vacuum drying. With the QDS system, the traditional drying process could be reduced to 30 min, without any negative effect on safety. The QDS process reduces the acid taste and increases the color intensity of fermented sausages. Moreover, some sensitive colorants (e.g., Ponceau 4R) do not fade during the process.

Drying of Solutions and Suspensions The most versatile method of drying liquids is spray drying. A solution or suspension with appropriate viscosity or consistency is sprayed into a cylindrical chamber in which it comes into contact with hot air. Spray drying consists of three steps: atomization of the fluid, the drying of droplets, and the separation of dry powder from the air stream (Figure 12). Atomization is achieved using a rotating wheel or a nozzle. This is the most important operation in the spray drying process. The method of fluid atomization and its variables determine the size and the size distribution of the drops, and their trajectory and speed in the drying chamber. The size of the drop determines the heat and mass transfer surface and influences heat and mass transfer resistances. Generally, the smaller the droplet diameter, the faster is the drying. Another important variable characterizing the spray is the size distribution. Because the rate of drying is inversely proportional to the droplet diameter, it is evident that the variability of the drying time will increase with the variability of the drop size. However, the stream of hot air conveys the drops, and their residence time in the drying chamber is not very dependent on their size. In consequence, small particles leave the drying chamber with a low water content and can be overdried, whereas large particles can be moist and underdried. The difference in moisture contents of small and large particles can be detrimental to the quality of the product during storage.

1 2

Air inlet

Exhaust air

4

3 5

Figure 12 Spray dryer: 1, drying chamber; 2, heater; 3, feed; 4, cyclones; 5, dry powder outlet. Reproduced with permission from Lewicki, P.P. (Ed.), 1999. Inzynieria Procesowa I Aparatura Przemyslu Spozywczego (Food Processing Engineering and Food Processing Equipment). Warsaw, Poland: Wydawnictwa Naukowo-Techniczne, © 1999 Wydawnictwa Naukowo-Techniczne.

Drying

Quality of Dried Products Drying causes numerous physical and chemical changes in food. Some of these changes can be used to enhance the quality and nutritional value of the food or to create new properties that are appreciated by consumers. Physical changes caused by drying include shrinkage, shape alteration, surface modification, and modification of mechanical properties. Most of these texture modifications are due to moisture and temperature gradients occurring in the solid being dried. The larger the gradients, the larger are the stresses developed in the material. Under the stress, the material shrinks, its shape is deformed, and the surface develops wrinkles and creases. Shrinkage, shape distortion, and surface modification depend on the method of drying and the extent of dehydration. Convective drying at a low drying rate creates small moisture gradients. Hence, the stresses developed in the material are small; the body shrinks uniformly; there is no shape change; and the surface, owing to the material's elasticity, evenly follows the change of size of the solid body. Under these conditions, shrinkage is equal to the volume of the evaporated water. The traditional method of dry-cured ham production is a good example of such a process. Convective drying done at high drying rates can produce large shrinkage stresses. The dry surface loses elasticity and cannot follow the change of volume. Consequently, the surface wrinkles and creases. If the drying is too fast, internal cracks and fissures are formed. These are the typical events occurring during spray drying, though they cannot be seen by the naked eye. Meat dried by convection or under vacuum is also exposed to these physical changes, some of which take place during production of semidry and dry sausages. In freeze drying there is no liquid phase, hence these are no moisture concentration gradients. Temperature gradients are too small to create large stresses and freeze-dried material retains the shape and size of the frozen material. Freezing is the step in the freeze drying process that causes injury to the internal structure of the material. Evaporation of water and increased concentration of solids change the mechanical properties of the solid. Resistance to deformation, chewiness, juiciness, ease of biting, cutting, slicing, etc., are altered and the extent of the change depends on the kind of dried material, the degree of dehydration, drying mode, and predrying treatment applied. Chemical changes caused by drying are mainly due to elevated temperature and increased concentration of solubles. In some cases, contact with air can have deleterious effects on the quality of the final product. Increased concentration of solubles can affect the quality of the product at water contents at which water can act as a solvent. Hence, changes of the degree of ionization, redox potential, solubility, and the catalytic activity of food constituents can be expected in material undergoing drying at high and moderate water contents. Proteins can be denatured or their spatial conformation can be changed, and high concentrations of reactants can promote chemical reactions. Nonenzymatic browning reactions can occur, and precursors can be formed that facilitate color changes during storage of dried product. Contact with oxygen causes oxidation of lipids and oxidation of pigments that occur naturally in food.

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Physical and chemical changes caused by drying usually affect the quality of the product unfavorably. However, with an appropriate choice of drying variables and mode of drying, suitable equipment, and predrying treatment, physical and chemical changes can be controlled and high-quality or novel sensory attributes can be obtained. Near infra-red equipment has been proposed as an on-line system to measure the water content and water activity at the product surface. This information can be used to set up the drying conditions in the drier (relative humidity, temperature, and air flow) as a function of the product characteristics.

See also: Ethnic Meat Products: Biltong: A Major South African Ethnic Meat Product; Germany; Mediterranean; Poland. Ham Production: Dry-Cured Ham. Packaging: Modified and Controlled Atmosphere. Refrigeration and Freezing Technology: Applications; Thawing. Sausages, Types of: Dry and Semidry

Further Reading Bender, A., 1992. Meat and meat products in human nutrition in developing countries. Food & Nutrition Paper 53. Rome: FAO. Chang, S.F., Huang, T.C., Pearson, A.M., 1996. Control of the dehydration process in production of intermediate-moisture meat products: A review. Advances in Food and Nutrition Research 39, 71–161. Collell, C., Gou, P., Picouet, P., et al., 2012. NIR technology for on-line determination of superficial aw and moisture content during the drying process of fermented sausages. Food Chemistry 135, 1750–1755. Doe, P.E. (Ed.), 1998. Fish Drying and Smoking: Production and Quality. Lancaster, PA: Technomic Publishing. Greensmith, M., 1998. Practical Dehydration. Cambridge, UK: Woodhead Publishing. Hui, Y.H., Wai Kit, Nip, Rogers, R.W., Young, O.A. (Eds.), 2001. Meat Science and Applications. New York: Marcel Dekker. Kudra, T., Mujumdar, A.S. (Eds.), 2001. Advanced Drying Technologies. New York: Marcel Dekker. Lewicki, P.P., 1998. Effect of pre-drying treatment, drying and rehydration on plant tissue properties: A review. International Journal of Food Properties 1, 1–22. Mujumdar, A.S. (Ed.), 1995. Handbook of Industrial Drying, Vols. 1 and 2. New York: Marcel Dekker. Oetjen, G.W., 1999. Freeze-drying. Weinheim: Wiley−VCH. Rahman, S. (Ed.), 1999. Handbook of Food Preservation. New York: Marcel Dekker. Stawczyk, J., Muñoz, I., Collell, C., Comaposada, J., 2009. Control system for sausage drying based on on-line NIR aw determination. Drying Technology 27, 1338–1343. Turner, I., Mujumdar, A.S. (Eds.), 1996. Mathematical Modeling and Numerical Techniques in Drying Technology. New York: Marcel Dekker. van't Land, C.M., 1991. Industrial Drying Equipment. Selection and Application. New York: Marcel Dekker. Varnam, A.H., Sutherland, J.P., 1995. Meat and Meat Products. London: Chapman and Hall.

Relevant Websites http://www.frigomeccanica.it/ Frigomeccanica S.p.A. http://www.kide.com Kide S.Coop. http://www.metalquimia.com Metalquimia S.A. http://www.refrica.com Refrigeración Casassas S.A (Refrica). http://www.travaglini.it/ Travaglini S.p.A. http://en.wikipedia.org/wiki/Drying Wikipedia.

E ECONOMICS

Meat Business and Public Policy NC Speer, Western Kentucky University, Bowling Green, KY, USA r 2014 Elsevier Ltd. All rights reserved.

Glossary

detailing trilateral trade law among the three countries. Rights These are the moral and/or legal rights of animals recognized by society. Traceability It details various production and/or attributes maintained throughout the supply chain. Welfare It is the general sense of animal well-being. World Trade Organization (WTO) It deals with legal rules of trade among nations ensuring that trade flows smoothly and freely.

Antibiotics These are the drugs utilized to treat and/or prevent various bacterial infections. Concentrated Animal Feeding Operation (CAFO) It is defined by the US Environmental Protection Agency describing animal production units that potentially fit specific pollution and/or waste profiles. Mandatory country-of-origin labeling (COOL) This is the US law dictating country of origin for various meat products. North American Free Trade Agreement (NAFTA) It is the agreement between the US, Canada, and Mexico

Background The past half century ushered in a period of sustained economic growth across the globe. Flourishing economies generally establish a higher standard of living that includes greater consumer demand for conveniences and measures of health and safety. More specific to the meat industry, economic growth also leads to changes in tastes and preferences and commonly includes pursuit of improving one's eating standards often characterized by a desire to include more animal protein within the diet. The expansionary period that began in the 1960s occurred largely within the developing regions (vs. developed countries) and strongly underpinned new opportunities for consumer spending on meat and meat products within those countries. Convergence of shifting consumer preferences coupled with an ever-expanding population strongly boosted meat demand. This subsequently led to the need for increased meat production throughout the world. Global meat production (beef, veal, pork, broiler, and turkey combined) grew more than 500% between 1960 and 2010 (45.447 vs. 243.396 mmtons, respectively).

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Despite steady growth and new market opportunities across the globe, the meat production business has proven especially challenging in recent years. Gains in overall production equate to a larger, more defined, and more easily targeted industry. That reality, along with advancements in technology and communication, has culminated to bring about increased attention and scrutiny for all participants associated with animal agriculture and meat production. Stakeholders at all levels are dealing with new and developing concerns surrounding the business. Aside from normal, routine consumer market issues, a number of nonroutine developments have arisen. Primarily, there is increasing desire for public involvement in various issues associated with meat production. Moreover, transition of economic growth away from developed countries to developing regions highlights the meat industry's connectedness to a variety of interacting forces throughout the world. As noted above, increasing economic prosperity often leads to increased meat consumption. In most businesses, that would typically prove favorable. However, for meat production, that reality also serves to be a double-edged sword. Once economic prosperity becomes sufficiently high, consumer

Encyclopedia of Meat Sciences, Volume 1

doi:10.1016/B978-0-12-384731-7.00208-7

Economics | Meat Business and Public Policy priorities tend to shift across a variety of attributes. For example, attributes associated with the production process (such as animal welfare) become more heavily weighted in purchasing decisions. In other words, fundamental attributes such as food safety, nutrition, taste, convenience, etc. become relatively less important items (albeit still essential), whereas other attributes become relatively more important. Therein enters many of the intricacies of decision making and policy navigation for the meat industry going forward. Many policy issues and challenges are relatively uncharted and potentially redefine how the industry carries out business from a strategic perspective. Key areas of policy arise in several key categories oriented around: (1) meat products; (2) production processes and the supply chain, and (3) overarching legal and trade issues. Several key issues are highlighted below. The list is neither comprehensive nor clear cut, given the variety of issues and potential for crossover among the categories. However, such imprecision further underscores the increasing complexity surrounding meat production. Product-oriented Policy Issues Food safety (pathogen-induced and residue derived) Health and wellness attributes

Trade/Legal Issues Labor/immigration regulation International trade regulations

Production-oriented Policy Issues Animal welfare and well-being Environmental stewardship and regulation Animal health/Antibiotics Industry Business regulation (including biofuels) Source verification and traceability Biotechnology Interaction with the biofuel industry

Animal Welfare Consumers generally expect respective food purchases to be nutritious, flavorful, and safe. However, rising affluence also leads to alternative attributes being increasingly important across the food system. Increasing interest and awareness among consumers of farm-to-fork connectedness have especially driven production-oriented issues to the forefront in recent years. The outcome being that all participants in the supply chain are investing more time and resources to dealing with such issues. Foremost among those issues includes animal welfare. The industry has traditionally countered broad concerns about animal welfare by demonstrating that animals grown in mainstream production systems are increasingly well cared for. In fact, overall management knowledge has never been more advanced. The upshot of those developments leads to better care and subsequent animal comfort. That reality is ultimately reflected by enhanced productivity across all of animal agriculture. There exists any number of favorable trends when considering items such as improved animal health, increased growth rates, and advances in reproductive efficiency. However, from a policy perspective, for many individuals, improved animal health, increased growth rates, and advances

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in reproductive efficiency are inadequate measures of animal care and/or welfare. Such opponents of the meat industry contend that well-being of an animal also include more intangible factors such as freedom from fear and/or freedom of social interaction. In particular, policy discussions often revolve around animal housing for animals involved in production – especially those housed in confinement operations. The issue typically includes topics such as gestation crates for sows, battery cages for laying hens, veal crates, and feedlot pens. Opponents of such housing argue that animals should be allowed opportunities for social interaction while also providing opportunity to turn around, lie down, stand up, and/or fully extend their limbs at all times. There have been a number of efforts, especially notable in the US, to pass state regulations to limit confinement-type operations to provide such attributes. Meanwhile, animal activists are also increasingly calling other management practices into question including concerns around beak trimming, castration, dehorning, clipping needle teeth, tail docking, etc. The primary argument is that meat production during the past few decades has dramatically changed. Activists advocate that modern meat production has increasingly moved to ‘industrial’ facilities emphasizing a concern only for productivity and completely disregards humane treatment of animals. Meanwhile, a recent rise of undercover investigations appearing on the internet from groups such as Humane Society of US, People for Ethical Treatment of Animals, and Mercy for Animals have provided ammunition for those calling for sweeping changes within animal agriculture, including potential elimination of raising livestock for consumption purposes. Such movements have led to laws in several states in the U.S. banning specific production practices (e.g., sow gestation crates, veal crates, and battery cages). The threat of ongoing lawsuits and/or ballot initiatives has led to several states (e.g., Ohio and Kentucky) to be proactive in developing animal care oversight boards. Simultaneously, throughout the European Union many such initiatives are underway. Public and social media outlets have also led to increasing awareness among consumers about animal welfare/animal care issues. Many large companies are responding accordingly. For example, McDonald's recently announced (February 2012) that it would work with suppliers to implement the phasing out of gestation crates associated with normal production practices. Similarly, the Humane Society of the US and the United Egg Producers announced a cooperative agreement to replace conventional battery cages with new housing systems providing hens more room and to prohibit sale of eggs and egg products that do not fall within the newly established guidelines (July 2011). Finally, the Compass Group – the largest global food and support service company – has also announced similar requirements for its pork and egg supply chain (March 2012). It should be noted that animal welfare is a very different concern from animal rights. Animal rights groups typically promote vegetarianism and believe that animals should not be utilized for any purpose, that is, some groups advocate a liberation agenda contending that animals have rights (similar to humans) and hence should not be utilized for any purpose (food, recreation, or research).

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Environmental Stewardship and Regulation Concerns around animal welfare and well-being often intersect with environmental stewardship and regulation. Growing adoption of production models emphasizing economies of scale draw the attention of those concerned about environmental degradation and subsequent societal costs. The forefront of environmental policy issues typically surrounds several key topics: waste or nutrient management, water quality and utilization, and air pollution or odor. Waste management becomes an especially important issue to manage when considering public perception and management of concentrated animal feeding operations (CAFOs), that is, such production units typically house larger numbers of animals in greater density (compared with more traditional production methods) and thereby larger amounts of waste are collected and/or stored in relatively small areas (e.g., manure lagoons). Regulation surrounding CAFOs has become increasingly stringent and rigorous over the years – all CAFO operators must maintain updated operating permits and undergo constant monitoring by regulatory agencies. However, opponents argue that if/when such resources are mismanaged and/or neglected, these units can potentially produce environmental problems – either acute or chronic in nature. Concerns about waste management inherently also involve policy discussions revolving around water quality: The concern being that CAFOs may represent increased potential for water contamination, be it point source (directly identifiable) or nonpoint source (diffuse) pollution. Therefore, animal agriculture finds itself dealing with regulatory pressures revolving around specific nutrients within various watersheds. And finally, increased regulatory pressure also comes on the air pollution/odor front, especially in areas where the urban/rural interface is mounting. From a more overarching, international perspective, the most notable environmental policy concern revolves around the very existence of meat animal production itself. Much of that attention in recent years result from the release of the United Nation's Foreign Agriculture Organization's publication entitled Livestock's Long Shadow (2006). The report asserting, “…climate change is the most serious challenge facing the human race. The report states that the livestock sector is a major player, responsible for 18 percent of greenhouse gas emissions measured in CO2 equivalent. This is a higher share than transportation.” The report has since been demonstrated to include several major miscalculations but nonetheless served to provide significant traction toward policy discussion and development. Meanwhile, environmental policy pressure also arises relative to land and/or resource utilization coupled with the integration of ecological and social equity. Those broader concerns invoke the concept of ‘sustainability’ and will more likely be an important driver of policy evolution within meat production systems in future years. A recent paper by Pretty et al. (see further reading) summarizes, “Vital work needs to be done to establish more precisely what ‘sustainable food’ represents, and to identify best practice standards across a wide range of activities throughout the [food supply chain].” Nonetheless, the concept has led to several key companies, along with external partners, to proactively address the issue.

For example, 2012 marked a new venture entitled the Global Roundtable for Sustainable Beef – a coalition of stakeholder companies and organizations. The founding members include: AllFlex, Allianca de Terra, Cargill, Elanco, Grupo de Trabalho da Pecuaria Sustentavel, JBS, McDonald's, Merck Animal Health, National Wildlife Federation, Rainforest Alliance, Roundtable for Sustainable Beef Australia, Solidaridad, The Nature Conservancy, Walmart, and World Wildlife Fund. The endeavor's mission is to assess and promote more efficient, environmentally sustainable beef production practices.

Antibiotics There generally exists a large degree of confusion and ambiguity about antibiotic use in livestock production. That is largely because such usage is a relatively nuanced issue often being commingled with the broader connotations surrounding consolidation and/or industrialization of animal agriculture. Therefore, there is a high degree of potential for misleading claims. Regardless, the use of antibiotics in food animal production derives broader concerns about antimicrobial resistance in humans (AMR). A variety of public interest groups are highly interested in the subject of AMR. Such concern is especially amplified when considering nontherapeutic use within livestock production. Opponents often claim that general and rampant overuse of antibiotics in animal agriculture leads to drug-resistant bacteria, an increasing threat to human beings. Such arguments are predicated on the following logic: Antibiotics fed to livestock at subtherapeutic levels facilitate establishment of resistant strains of bacteria and absolute containment at the local farm environment proves elusive. That scenario inevitably put citizens at risk because such strains prove unresponsive to treatment if they are able to cause illness. Therefore, the argument is that such use must be curtailed and future approval of new antibiotics in livestock should be preempted (new development should be saved for human usage). AMR concern often gets leveraged to advance ideologies and/or policy proposals to limit antibiotic use in farm animals. The most commonly cited example supporting an antibiotic ban comes from Denmark, where nontherapeutic antibiotic use has been banned in animal agriculture. However, since the ban, therapeutic use in animal production has increased. Moreover, no scientific documentation exists that reflect antibiotic resistance in the human population has declined since the ban. Policy implementation suggesting simple fixes or solutions leads to false sense of security. That is because numerous complexities surround development of antibiotic resistance. Several other risk factors also contribute to development of AMR, including large hospitals, socialized care of elderly persons, and increased social interaction via international travel. Therefore, policy must key on proper assessment and subsequent management of risk – comprehensive, sciencebased strategies in both livestock production and human health. Moreover, AMR results from intricate interactions among (1) specific antibiotic class, (2) specific pathogen, and (3) host population. Therefore, predicting and/or preventing

Economics | Meat Business and Public Policy broad or wide-scale resistance, based on simple policy solutions, is highly challenging because of the large number of specific antibiotic/pathogen/host combinations. As a result, there is no scientifically documented link establishing antibiotic use in livestock and increased resistance in humans. In fact, quantified research assessment of potential farm-topatient resistance represents a ‘very low risk of human treatment failure’. Finally, policy pressure revolving around antibiotic resistance often invokes the previous two issues discussed: animal welfare and environmental regulation. That is because antibiotic usage in animal production commonly gets tied to the overall ‘factory’ or ‘industrial’ farming model – the argument being that antibiotic utilization would be unnecessary if animals were not housed in confinement. Therefore, the three issues often become inherently linked with policy discussion.

Dietary Guidelines Obesity progressively receives attention as a global epidemic as obesity rates continue to climb. For example, the Center for Disease Control estimates that two-thirds of the US population is now overweight; more than half of that segment, or fully one-third of the total population, falls into the obese categorization. To that extent, human weight management is not simply an individual matter; rather, it is now a collective, public health concern stemming from lost productivity and rising health care costs associated with obesity. Rising prevalence of obesity and subsequent health problems (claims revolving around type-2 diabetes, heart disease, various cancer types, etc.) have served as a platform to advance a vegan and/or vegetarian agenda. From a public health point of view, many argue that the parallels among increased meat consumption and obesity rates represent a meaningful relationship. Therefore, reduced meat consumption is often promoted as conducive with healthier lifestyles and hence should be eliminated from the diet. These opposition groups often utilize rhetoric revolving around a general theme of meat being unnecessary in the diet and detrimental to individual health. The dietary issue has been especially leveraged of late around other matters within animal agriculture, that is, food choice and/or availability converges with other matters of policy (such as environmental degradation, resource exploitation, animal welfare, etc.). Stated another way, policy discussions addressing healthcare costs (due to heart disease, obesity, type-2 diabetes, and the like) are sometimes aimed directly at animal agriculture, citing meat production and increasing corporate pressures as contributing to broader health concerns.

International Trade Structural shifts in developing countries have moved economic activity to new areas of the world. Meanwhile, technology gains in transportation and communication have driven international trade of all types of material goods as costs of logistics and supply chain coordination have declined. However, as global interconnectedness increases, managing global

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governance and trade policy becomes both increasingly difficult and important. That reality is evidenced by several key, long-standing trade embargoes around meat and/or meat products. When such embargoes are principally unfounded, it often escalates to retaliatory trade measures that include other products including grain and/or other manufactured material goods. Animal health is an especially important consideration with regard to meat production and international trade policy. Therefore, moving animals and/or meat products across international borders requires more stringent sanitary and phytosanitary policies. International trade requirements increasingly mandate some form of identity preservation and source verification. For such verification to be meaningful, traceability must exist throughout the entire supply chain. Therefore, many countries now require individual animal identification and meat traceability as precursors for import status. Traceability is often a mandate to ensure that animal disease requirements dictated by the World Organization for Animal Health (OIE) are strictly followed. The OIE promotes international cooperation to control the spread of transboundary animal diseases while also providing expertise to establish public health standards and improve legal framework for trade. Countries with such systems generally possess increased competitive advantage when negotiating market access with those not possessing such systems. However, implementation of such systems can prove cumbersome, complicated, and often controversial. That has been especially evident in the US as the country progresses through various attempts at mandatory animal identification. The attempts are made to ensure rapid tracking capabilities in the event of serious animal disease events and/or outbreaks (e.g., bovine spongiform encephalopathy or foot and mouth disease, respectively). Animal disease traceability is very different from marketdriven traceability – the latter more focused on value-added credence attributes such as age verification, natural programs, animal welfare, etc. A secondary level of such discussion revolves around country-of-origin labeling (COOL). Implementation of a mandatory system within the US (effective 2008) has played an especially important role within the North American Free Trade Agreement (NAFTA) framework. Legality of the labeling law is now in question due to a 2011 World Trade Organization (WTO) ruling: COOL is not WTO compliant, as per NAFTA requirements, and effectively represents a nontariff trade barrier. Regardless of the dispute's outcome, the law will more likely lead to important ramifications around a whole host of products in future trade negotiations. Finally, many countries often must manage trade policy from a more internal approach. Those discussions can be especially contentious with food and/or food production. Many antitrade proponents, regardless of the country in question, promote a sense of national security – food production should not be included in discussions and/or negotiations revolving around trade. That perspective argues food should remain immune from the broader forces of global economic change. That influence makes trade development policy especially difficult because consumers in all countries desire goods that come from free trade – which is often in the form of meat or

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meat products. That ultimately creates an inconsistency between protectionism on one side and free market capitalism on the other.

Interaction with the Biofuel Industry Introduction of biofuels policy in the US initiated some important influences on the meat production business. It represents a whole new dimension for agriculture that has arisen during the past five years or so. The dynamics have dramatically shifted the business environment for all of agriculture (not to mention its indirect influence on consumers across a number of venues). From a policy perspective, it has initiated a more wide-reaching debate about food versus fuel. More directly, the influence of ethanol policy on the meat production business has been derived primarily in the form of higher feed and other input costs. However, it has also created an inexorable linkage among commodities of all types. That connectedness among markets along with increasing speed of commerce and globalized trade ultimately means that biofuel policy in any country has ramifications to the meat industry throughout the world. Specifically, it has given rise in recent years to renewed concerns about food costs and the role of speculators on all commodity prices across the globe – speculators often being accused of unduly profiting from their respective positions while the rest of the world (especially the impoverished) are unduly punished by rising costs.

Internal Business Regulation Much of the discussion above focuses primarily on public– industry interaction. However, the meat industry also wrestles with several ongoing and contentious internal policy struggles because many of the traditional trade and production strategies have blurred over time. Most notably, there is divided ideology about adaptation strategies and future competitiveness – much of it centered around production sector competitiveness issues. Consolidation remains a very important and controversial issue within agriculture with distinct and well-entrenched opinions about its long-term impact on the industry. To date, much of agriculture's transition stems from consolidation in the food processing, manufacturing, wholesaling, retailing, and service sectors. The industry has evolved to become more efficient to meet rising consumer demand across the globe. Coordination of the supply chain facilitates improved cost controls, more efficient scheduling of inputs, and processing assets. The meat industry has transitioned accordingly – from relatively uncoordinated commodity-sorting systems to growing adoption of more specialized production. Restaurant and retail companies desire to offer high quality, competitive products while also facilitating consistent and predictable inventory turnover; in turn, processors seek development of specified capabilities from producers to deliver those attributes. These endeavors increasingly enhance the bottom line for companies, especially in the face of rising costs; informationbased supply chain coordination efforts improve efficiency while emphasis on differentiated, value-enhanced production

boosts revenue. That has not occurred at the exclusion of the production sector (albeit comparatively more pronounced in the pork and poultry sectors compared with the beef complex). The trend to larger operations has occurred to leverage some economies of scale and management, but it is done not only to implement cost efficiencies but also to facilitate better input quality control and to ensure that specifications are met at all levels of production. However, the meat business, at least at the production level, remains relatively large, diverse, and fragmented. Consequently, there exists wide opinion about how business should be conducted: The struggle often vacillates between pressures to evolve to ever-increasingly synchronized systems approach versus maintaining a more traditional independent, segmented structure (adhering to other more important values surrounding production systems). Those arguing for the latter have seemingly been bolstered with renewed consumer interest in the food system – that is reflected by success of several popular books during the past decade along with various documentaries. Such coverage tries to engage the audience in seeing the connections between retail and restaurant food business and ensuing production of the products which they merchandise.

Conclusions Meat production and animal agriculture are increasingly an important, dynamic, and demanding business from a number of perspectives. Animal agriculture must continue to pursue increased output and efficiencies in order to satisfy consumer demand and meet the needs of a growing global population. Simultaneously, those same consumers increasingly view themselves as stakeholders in the production and marketing system. Food activism has steadily increased with each passing decade since the 1970s, gaining significant traction in recent years. Regulatory reform must consider both cost competitiveness and social implications.

See also: Animal Health Risk Analysis. Human Nutrition: Meat and Human Diet: Facts and Myths. Manure/Waste Management: Manure Management; Waste Management in Europe. Microorganisms and Resistance to Antibiotics, the Ubiquity of: Antibiotic Resistance by Microorganisms; Potential Environmental and Wildlife Sources of Microorganisms in Meat. Preslaughter Handling: Preslaughter Handling. Professional Organizations. Residues in Meat and Meat Products: Feed and Drug Residues. Slaughter, Ethics, and the Law

Further Reading Armbruster, W., Stenholm, C., Armstrong, J., et al., 2006. The Future of Animal Agriculture in North America. Oak Brook, IL: Farm Foundation. Field, T.G., Taylor, R.E., 2008. Scientific Farm Animal Production. ninth ed. New York: Prentice-Hall. Hurd, H.S., Doores, S., Hayes, D., et al., 2004. Public health consequences of macrolide use in food animals: A deterministic risk assessment. Journal of Food Protection 67 (5), 980–992.

Economics | Meat Business and Public Policy NIAA, 2011. Consumers Stake in Today's Food Production: Meeting Growing Production Demands With Integrity. Colorado Springs, CO: National Institute for Animal Agriculture. Pretty, J., Sutherland, W.J., Ashby, J., et al., 2010. The top 100 questions of importance of the future of global agriculture. International Journal of Agricultural 8 (4), 219–236. Steinfeld, H., Gerber, P., Wassenaar, T., et al., 2006. Livestock's Long Shadow: Environmental Issues and Options. Rome: Food and Agriculture Organization of the United Nations. ISBN: 978-92-5-105571-7.

Relevant Websites http://www.soundagscience.org/ Animal Agriculture Alliance.

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http://www.fao.org/ Food and Agriculture Organization of United Nations. http://www.animalagriculture.org/ National Institute for Animal Agriculture. http://www.animalagriculture.org/Solutions/Proceedings/Annual%20Conference/2011/ White%20Paper.pdf National Institute for Animal Agriculture. http://www.usmef.org/ US Meat Export Federation. http://www.oie.int/ World Organization for Animal Health. http://www.wto.org/ World Trade Organization.

ELECTRICAL STIMULATION

CE Devine, The New Zealand Institute for Plant and Food Research, Hamilton, New Zealand DL Hopkins, NSW Department of Primary Industries, Cowra, NSW, Australia IH Hwang, Biotechnology Chonbuk National University, Jeonju City, Korea DM Ferguson, CSIRO Livestock Industries, Armidale, NSW, Australia I Richards, Meat and Livestock Australia, South Brisbane, QLD, Australia r 2014 Elsevier Ltd. All rights reserved.

Glossary Aging The process of meat tenderization that is an enzymatic process occurring over time. Calpains Components of the enzyme system acting on cytoskeletal proteins during meat tenderization. Current Electrical term defining flow of electric charge. Cytoskeletal proteins A set of structural proteins (includes titin, nebulin, and desmin) that are denatured by calpains. dpH/dt The rate of fall in pH that takes place following the electrical stimulation. Drip or purge Water that increases over time arising from the protein denaturation as meat tenderises – it is additional to that from prerigor myosin denaturation that can also occur. Electrical stimulation (ES) The application of an electric current through a carcass postmortem that accelerates the rigor process. Hot boning A process when the meat is removed from the carcasses before rigor mortis in contrast to cold boning when meat is removed after rigor mortis. Myofibrillar proteins The muscle contractile proteins, actin and myosin. ΔpH The actual fall in pH that occurs immediately after electrical stimulation.

Introduction ‘Electrical stimulation’ (ES) or ‘stimulation’ are general terms used for describing a passage of any electrical current through a muscle or carcass and the abbreviation ES is used in this article generally to apply to the process in which an electric current is passed through carcasses with the aim of ensuring that the meat is tender. Tenderness is a major consumer requirement (toughness is its inverse) and it is quantified using either consumer panels, trained sensory panels, or objective measurements such as shear force (force required to shear through a cooked piece of meat). ES has been used to improve the tenderness of meat from deer, goats, sheep, cattle, and various poultry species, and in certain circumstances for pigs, and is perhaps one of the recent most significant factors in improving meat quality. In some situations its application has introduced small problems of its own such as human safety

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Postmortem The period after harvest when the pH falls until rigor mortis and subsequent aging. Preslaughter The period before slaughter where factors such as stress can affect meat quality. Protein denaturation A process whereby proteins lose their tertiary and secondary structure such as by application of acids or heat – water that is part of the tertiary structure can be released. Pulse waveforms Characteristics of specific electrical stimulation parameters. Rigor A term for individual muscle fibers that have been depleted of adenosine triphosphate, whereas rigor mortis is a term where muscles stiffen after all muscle fibers enter rigor. Shear force The force (N) applied to a standardized piece of meat to shear it. Shortening A process that occurs when prerigor muscle is cooled below 10 °C – additionally it also occurs as muscles enter rigor (rigor shortening). Ultimate pH The pH that is reached when muscles reach rigor mortis. Voltage Electrical term defining the electrical potential difference.

considerations, but overall the improvement in tenderness far outweighs these minor problems. Although it is not possible to increase meat tenderness beyond that limited by connective tissue, it is possible to ensure the meat routinely reaches the highest degree of tenderness it is capable of achieving. ES of muscle from harvested animals hastens the process of rigor mortis (defined when adenosine triphosphate (ATP) production ceases). It does this by causing muscles to undergo work via anaerobic glycolysis, resulting in an initial pH fall (DpH) followed by a change in the rate of pH fall (dpH/dt). The combined effect is that the muscles enter rigor mortis before the muscle temperature falls to values producing cold shortening and toughening. Early post slaughter, stimulation can be applied using relatively low voltages that effectively operate via the nervous system. With increasing delays before stimulation, higher voltages are then required to directly stimulate the muscles.

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The electrical parameters generally used must consider the appropriate waveform and pulse frequency, duration, prestimulation delay, chilling rate, and type of species involved. Although ES ensures that cold shortening is avoided, aging also starts at a higher temperature and is consequently more rapid. However, evidence suggests that there are other mechanisms involved in tenderization (defined as the reduction in toughness postrigor), such as modification of the enzyme systems and possibly fiber disruption and protection of the enzymes responsible for tenderization. ES must be considered as part of a total process from slaughter through chilling to final sale, and has particular advantages for hot boning, where the shortening and toughening conditions that would occur for nonstimulated muscles during chilling are avoided. With appropriate ES and chilling rates, hot-boned meat is as tender as normal cold-boned meat, especially if a wrapping procedure is also used to avoid shortening.

History The association between muscle/meat and electricity started with Galvani, although the earliest reported use for meat improvement was by Benjamin Franklin, in 1749, who electrocuted turkeys, with the result that they were ‘uncommonly tender.’ During the 1950 s it was shown that ES could improve meat tenderness of beef, but no commercial application of the process occurred. Stimulation of horse muscle was used experimentally to examine the microbiology of pre and postrigor meat from the same animal at the same temperature. The incorporation of a practical system into the slaughtering process was first used in New Zealand and then Australia to avoid toughness resulting from cold shortening. It is now widely used in many other countries with a variety of parameters (Box 1). In New Zealand, ES was originally used to accelerate rigor mortis before sheep meat and beef was frozen. For cattle, shortening is less of an issue as temperatures fall more slowly than sheep, but ES in many circumstances enhances tenderization with a general improvement in quality and reduction in the differences among cattle breeds. In initial commercial operations, loins and legs from nonstimulated lamb carcasses put into a blast freezer (−5 °C within 2 h of slaughter) and later cooked from the frozen state were exceedingly tough, with only approximately 1% of the loins assessed as acceptable on the basis of shear force.

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In contrast, nonaged loins from similarly processed, but high voltage-stimulated lamb carcasses gave approximately 75% of shear force values in the acceptable range. For small, easyto-chill lambs, the improvement is therefore dramatic, ensuring that the majority of rapidly frozen meat is acceptable. For cattle, shortening is less of an issue, but ES still enhances the rate of tenderization. The combination of ES and a specified further aging period to achieve a desired tenderness level underpins the accelerated conditioning and aging (AC&A) standard that currently applies in New Zealand abattoirs for sheep and lambs.

Description Events During Electrical Stimulation ES involves passing an electric current through the bodies or carcasses of freshly harvested animals. This electric current causes the muscles to contract, increasing the rate of glycolysis and results in an immediate reduction in muscle pH (DpH) that ranges from 0.6 pH units at 35 °C to 0.018 units at 15 °C, suggesting that ES of warm carcasses should take place soon after slaughter to maximize efficacy. Following the pH fall, there is a temperature-dependent acceleration of the rate of glycolysis (dpH/dt) and subsequent early rigor mortis development (Figure 1). The increased rate of pH fall after ES seems to occur with a wide range of electrical parameters and even occurs as a consequence of high frequency electrical stunning and kicking movements post slaughter. Although the DpH is generally lower with low-voltage ES, the same rate of poststimulation pH fall is achieved as with high-voltage systems. The rapid development of rigor mortis ensures that postmortem aging starts earlier, improving meat color, and provides increased muscle stiffness that facilitates early boning.

Electrical Stimulation Systems There are numerous physical methods by which ES can be applied and many different possible electrical specifications (see Box 1 for representative electrical parameters). A new generation of systems developed in Australia for both sheep/ lambs and beef were designed to impart the response observed with high-voltage ES, but without the danger associated with such systems. The pulse width is reduced and the peak voltage

Box 1 Typical ES parameters in common commercial use. It should be noted that these are representative and many variations are used • 200 V, 60 Hz applied in bursts of 1 s on, 1 s off for 60 s duration for beef in the US • 1130 V peak, 14.3 alternating pulses per s applied for 90 s within 30 min of slaughter for sheep are lambs in New Zealand • 80 V peak, 15 unipolar pulses per s, square or half sine wave, applied for 15–30 s within 5 min of slaughter for beef in New Zealand • 800 V rms bidirectional half-sinusoidal, 14.3 pulses per s applied within 40 min postslaughter for beef and lamb • 80 V peak, 15 unipolar pulses per s applied for 30 s within 20 min of slaughter for beef in Sweden • 40 V peak, 15 unipolar pulses per s applied using an anal probe with durations for 40–50 s within 5 min of slaughter for beef in Australia • Voltage controlled to deliver up to 2 A peak for 30 s at 15 pulses per s up to 2.5 ms duration applied within 30–40 min for sheep and lambs in Australia. A variation to this includes modulated frequency, for example, for a 6 electrode system 10, 15, 25, 10, 15, and 25 Hz

• 400 V peak 2 ms pulses at 15 pulses per s in Australia for beef

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7.2 7.0

ΔpH

6.8 Cold shortening possible 6.6 Unstimulated

6.4

Stimulated

pH

6.2 6.0 Thaw shortening possible

5.8 5.6

Ultimate pH (rigor mortis)

5.4 5.2 5.0 0

2

4

6

8

10

12

Time (hours postmortem) Figure 1 Postmortem pH fall in muscles after ES and held at a constant 35 °C. During stimulation, the muscle pH falls (DpH). Nonstimulated beef muscle has a rate of pH fall (dpH/dt) of 0.18 pH units per hour. After stimulation, the dpH/dt is increased to 0.3 pH units per hour. The time that muscle is at cold shortening temperatures is clearly reduced.

is decreased compared with high voltage ES, but the lower rms voltage developed (rms is the ‘average’ voltage and is explained later) ensures that the systems are much safer for workers (see Box 1). Regardless of species, ES can be applied immediately after slaughter or at any point in time thereafter until the muscles become unresponsive. The time until muscles fail to respond is related to the natural rate and extent of glycolysis and the voltage and or current being applied, the duration of ES, and the type of response expected. Procedures range from stimulating stunned but not bled animals, to whole bodies, skinned bodies, carcasses, or sides or even primal cuts. Most commercial ES systems employ the carcass rail as ground and a live electrode contacts some other point of the body, carcass, or side as shown in Figures 2, 3a,b, and 4. In the most basic systems, the live electrode contact is a clip manually applied to the head or neck of the body (such a clip would replace the lower rubbing bar in Figure 2) as it is suspended by one or both hind legs, resulting in a current flow to the grounded rail support or top electrode. A range of other systems have also been developed for beef ES, covering both batch and continuous operations. The batch systems might involve manually inserted electrodes or electrode bars that move out to make contact with the body or carcass. In these systems, the carcass or carcasses are enclosed within a shielded cabinet during ES. Continuous systems consist of stationary rubbing electrodes (Figures 2 and 3) or, where the ES is applied to carcasses before inspection, the electrode system consists of a moving series of electrodes. For poultry, heads can be placed in a trough filled with water with the rail being the other electrode. In New Zealand, electrical stunning of cattle is widely used; and the stunning current is applied to a restrained head in a stunning box and followed by application of additional

Figure 2 Low-voltage ES of cattle in a meat processing plant. The current (120–400 mA, 15 pulses per s) passes between the top rubbing bar electrode and a lower rubbing bar electrode (often earthed). An alternative arrangement can use a clip attached to the nose. The duration of ES ranges from 30 to 60 s. Bleeding out rate is generally increased. Photograph courtesy of Meat and Livestock Australia.

currents to cause cardiac arrest (if nonhalal) with reduced poststun carcass movements. Following stunning, current is often immediately applied to the body for ES before the animals are ejected from the stunning box in some New Zealand plants. Some carcass electrical immobilization may cause a pH fall (although some recent immobilization parameters do not cause a pH fall and are exempt) as will the application of electrodes to the back muscles to stiffen them during downward hide pulling. New immobilization systems have been developed in Australia for sheep/lambs and beef.

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(a)

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(b)

Figure 3 (a) A medium voltage ES system for electrically stimulating lamb bodies prior to dressing at the start of the chain, typical of Australian new generation systems for sheep predressing. The application of ES is through the rail to the hind leg hocks- also commercially referred to as transverse leg stimulation. Photograph courtesy New South Wales Primary Industries, Australia. (b) A medium voltage ES system for electrically stimulating lamb bodies postdressing at the end of the chain, typical of Australian new generation systems for sheep postdressing. The application of ES is from the electrode at top rail to the hind leg with only one carcass on any electrode at any one time. Photograph courtesy New South Wales Primary Industries, Australia.

make contact, at shoulder level, with an electrode supplied with high voltage pulses (see Figure 4).

Electrical Stimulation Parameters

Figure 4 A typical high-throughput system using a high voltage ES facility for sheep postdressing, in which the current passes through the carcass between two rubbing bars. Photograph courtesy New South Wales Primary Industries, Australia.

More sophistication and protection for humans is required as voltages increase, such as in high-voltage systems for sheep and lambs (Figure 4). However, safety is enhanced with the development of systems with shorter pulse widths and increased voltages utilizing reduced rms voltages. In one New Zealand abattoir, an effective single in-line high-voltage ES system coped with a peak kill of 20 000 carcasses per day. Typically, for high voltage situations, the ES is applied less than 30 min after slaughter where dressed carcasses are suspended by metal or plastic skids and gambrels from a grounded rail and moved through a stimulation tunnel to

Any electric current above a certain threshold will stimulate muscles, and for this reason stunning or immobilization currents can have a beneficial effect on tenderness by also accelerating glycolysis. The current flow is dictated by the applied voltage and carcass characteristics such as pelt cover, animal size (determining resistance) and fatness (potential insulation), and contact area (in particular reduced contact with shin). However, in commercial situations where high voltage ES is used, large peak current flows occur (e.g., in excess of 2 A peak per carcass). In situations where many carcasses are stimulated simultaneously on the same electrode system, very sophisticated power supplies, delivering up to 60 A total, are needed for the pulsed currents and currents are not necessarily shared equally between carcasses. Development of new systems for sheep/lambs and beef in Australia using short pulse widths and moderate voltages use segmented electrodes to ensure that each electrode only contacts one carcass at a time. This allows computer-controlled electronics to give a precise, but adjustable current to each carcass to match the requirements of a particular carcass type (Figures 2 and 3a,b). The current pulses in these systems use very rapid rise times that appear to provide a greater stimulation effect with lower peak current to give very effective results (Box 2). Voltages used vary from 32 to 3600 V (historically). The value specified might be that of the peak or the rms (root mean square) voltage, or in some cases the average over the total time. The rms voltage is the effective value or heating

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Electrical Stimulation

Box 2 Meat characteristics following ES. Color (redness (a*), color stability at 630/580 nm, shear force (N), pH, predicted temperature at pH 6.0 (°C), for the m. longissimus of electrically stimulated (800 mA, pulse width 0.5 ms, peak voltage of 300 V, 15 Hz, for 60 s) and nonstimulated lamb carcasses (40 per treatment). Chilled at 4.2 °C. All values are predicted means (s.e.d.) Trait

Stimulateda Nonstimulated s.e.d.

Initial loin pH Predicted temperature at pH 6.0 Shear force (N) at 1-day aging Redness (a*) Color stability (630/580 nm)

6.34a 24.8b 36.0a 7.70a 3.20a

6.79b 13.9a 44.0b 7.00a 3.00a

0.04 1.50 2.40 0.32 0.14

a

Stimulation treatment was at a current of 800 mA with a pulse width of 0.5 ms for duration required. Means followed by the same letter in a row are not significantly different (P¼ .05). Source: Adapted from Toohey, E.S., Hopkins, D.L., Stanley, D.F., Nielsen, S.G., 2008. The impact of new generation pre-dressing medium-voltage electrical stimulation on tenderness and colour stability in lamb meat. Meat Science 79, 683−691.

capacity of a waveform. For a sine wave, the rms value is the peak voltage divided by √2. For 1130 V peak, 50 Hz, the rms voltage is 800 V. However, for many derived (nonsinusoidal) waveforms the rms may be quite different and ineffective. For one version, termed the Meat Industry Research Institute of New Zealand (MIRINZ) waveform, every seventh half-sine wave of a 50 Hz sine wave is used and the rms voltage is the peak voltage divided by √14. Figure 5 illustrates the meaning of the different terms used to describe voltages and waveforms. Defining a waveform with a frequency (expressed in Hz) is likely to lead to confusion unless the waveform is also defined in terms of shape, duration, and pulse spacing. Square waves also can be used and may be unipolar or bipolar and applied as discrete pulses or even as pulse trains. Extensive research in Australia particularly in sheep and lambs has demonstrated that ES systems must be validated and optimized to ensure effective operation – in other words mere application of electricity does not guarantee a satisfactory result. In instances where this does not happen or system monitoring is not employed ES can be relatively ineffective. In some situations with multielectrode systems, lights are used to indicate when each electrode is operating, to limit ineffective ES. Although any stimulation increases dpH/dt, it is only optimum parameters (duration, peak voltage, and pulse characteristics) that increase the fall DpH significantly. It is likely where ES is not regarded as effective or useful the resultant DpH has not been sufficient.

Safety Occupational safety has been of utmost importance during experimentation and implementation of ES, especially when peak voltages as high as 1130 V are used. In some instances, safety concerns have effectively prevented commercial adoption of the process but, as indicated, modifications to pulse width resulting in much lower rms voltages have meant that the safety concerns are negligible. When required, isolating

switches, warning lights, and proximity switches are used. For frequencies of 50 or 60 Hz, cardiac arrest is highly likely with any form of contact by personnel, but cardiac arrest is less likely with the pulsed waveforms now used. Systems have been developed for ES of beef carcasses ranging from continuous operations to manual insertion of electrodes. In past systems, the carcasses were enclosed within a shielded cabinet during ES. The new narrow-pulse systems have eliminated the need for this shielding. There are also food safety issues to consider. For example, where the stimulation is applied to carcasses before inspection, but after the hide is removed, the electrode system needs to be sterilized between carcasses. Until recently, plants have applied ES to beef carcasses with an electrode on the nose or stick wound and grounding via the rail from which the carcass is suspended. Under these conditions the resistance of the narrow portion of the hind leg with high bone and tendon but low muscle content can be very high. The relatively high resistance encountered is due not to the bone component per se but to the narrow points of contact at the rigid interface, thus reducing contact area and severely limiting current flow. An anal electrode has been used in Australia for beef to provide good contact in the hindquarter, and using this system effective low-voltage ES has been achieved. The new narrow-pulse systems allow automatic application (Figures 2 and 3a,b) using rub bars as higher peak voltages can be used safely to overcome the increased electrical resistance of the bars.

Other Meat Quality Responses to Stimulation In most instances ES is applied with the aim of ultimately improving tenderness, but there have been reported some minor adverse effects such as ES-mediated meat color changes. In most cases the stimulation has been suboptimal/ineffective and the chilling conditions inappropriate. It seems unlikely that electricity on its own affects meat color. The potential interaction of low pH and high temperature on prerigor meat are only present for a short time due to early rigor mortis (see below). Because of early rigor following ES, color changes are not identical at 24 h (typical results in Box 2). This is expected as electrically stimulated meat is in fact biochemically further along the postmortem pathway, including being more tender – this makes a slight difference at 24 h but not is not significant for aged meat. Similarly, glycolysis is rapid following ES so the consequent early rigor mortis, even with a slow temperature decline of very large/fat beef carcasses, is so brief and does not produce significant myosin denaturation (it does not therefore mimic pale, soft, exudative (PSE) pork). Any drip that does occur following ES is expected as a consequence of early rapid tenderization, but the extent is similar to that without ES for the same tenderness (see below). Denaturation of muscle protein (myosin) during the prerigor period, can occur to a small extent even for nonstimulated carcasses if the chilling rate is slow and even occurs to some degree under normal chilling conditions for all species – it is a characteristic of prerigor muscle, so it is not a direct stimulation effect. The temperature and pH conditions that

Electrical Stimulation

50 Hz

491

Vrms (0.707 peak)

Vpeak +

0

(a)

−

14.28 ½ sine wave pulses per second

+ 0 (b)

−

Space Pulse width

7 Hz

+ 0 (c)

−

15 square wave pulses per second

+

0 (d)

0

70

140

Time (ms) Figure 5 Terms used to describe pulses and waveforms illustrated by sinusoidal (a and c), half sinusoidal (b) and square wave pulses (d). In (a) there are 50 sinusoidal cycles per second (100 half sine wave pulses); peak and rms voltages are indicated. The pulses in (b) are obtained by cutting out half-sinusoidal pulses, which in this case gives 10 ms duration pulses, 14.28 pulses per second, with the same peak voltage. The pulse width (mark) and space between pulses give the mark-to-space ratio used to specify a single repetitive cycle, with the polarity of pulses and the number of cycles per second required to complete the description. The waveforms (b) and (c) both have the same period (inverse of frequency) and peak amplitude, but have different shape characteristics. Square wave pulses (d) can have variable widths depending on the characteristics desirable, and only a particular stimulation waveform is shown here.

result in myosin denaturation and drip have been modeled by Gerald Offer for pork and beef during glycolysis and cooling and he showed that once rigor occurs there is no further myosin denaturation. In particular, Offer stated, “If the rate of glycolysis is very high, although the muscle experiences particularly severe denaturing conditions so that the rate constant of denaturation reaches high levels, these are experienced for a sufficiently short time that the total amount of myosin denatured is lower rather than higher.” This means that the brief prerigor exposure to elevated temperatures, following ES, reduces myosin related drip compared with longer prerigor exposure without ES at lower temperatures. In fact increasing stimulation effectiveness increases DpH and this in turn reduces the time to rigor and thus exposure to denaturation conditions.

Without ES, muscle held at constant elevated prerigor temperatures appears to have a reduced tenderization by inhibiting calpain activity. In contrast, with ES not only the prerigor exposure duration is reduced but also some fibers enter rigor almost immediately and the rest of the muscle fibers rapidly follow – the degree depending on initial prerigor glycogen – so full tenderization can then take place. Postrigor cytoskeletal denaturation and tenderization is associated with production of free water. This means that the early appearance of drip as muscles tenderize rapidly at high temperatures, is a consequence of rapid and extensive tenderization, but there is no more drip for equivalent tenderization. The appearance of drip is unfortunate, but its appearance means meat has tenderized. Conditions that reduce drip generally also reduce tenderization.

492

Electrical Stimulation

Factors That Influence Effectiveness of Stimulation Fall in pH upon Stimulation The magnitude of DpH is governed by muscle fiber type, initial glycogen stores within the muscle, the electrical characteristics (current, frequency, pulse shape, and stimulation duration), temperature of muscle, and the time after death at which ES is applied. Postmortem delay, through a combination of lower muscle temperature and lower initial pH reduces DpH, but not the extent of pH reached – ES effectiveness and tenderness is not reduced.

Effects of Muscle Type on Stimulation Response There is a difference in response to stimulation between various muscles that depends on muscle fiber type and the ratio of fiber types. Fast-twitch beef m. cutaneous trunci, largely composed of white muscle fibers, gives higher values for DpH (and dpH/dt), whereas in the slow-twitch m. masseter, composed of red fibers, there is neither a distinct DpH nor an acceleration of dpH/dt, which is naturally rapid (0.4 pH units per h).

Frequency, Voltage/Current, Pulse Shape, and Polarity Effects Most beef and sheep muscles have a greater physical response, prolonged contraction, and a concomitantly greater DpH in the range from 9 to 16 pulses per second than at any other frequency, and most ES systems encompass these frequencies (Figure 6). In general, the higher the current (at a constant resistance, current increases with increased voltage) the greater will be the effect. This response will be asymptotic to some maximal value, however, so continually increasing the current will not lead to a continuing increase in effect once the ES parameters are supramaximal. The advantage of pulsed currents is that the energy of the electrical input is lower, with a

0.8 0.7

ΔpH

0.6 0.5 0.4 0.3 0.2 0

20

40

60

80

100

Pulses per second Figure 6 The effect of pulse frequency on the DpH value. The greatest effect lies between 7 and 15 pulses per second and these frequencies are chosen in most ES systems, although the effect is significant at all frequencies. With pulsed waveforms, the electrical input to the carcass is low and this is a major advantage, with lower heating.

smaller chance of melting structures in the current pathway such as the Achilles tendon. There is recent evidence that the pulse shape (at a constant peak voltage/current) has an influence on the ES effect. Rapidrise time rectangular pulses appear to have a greater stimulation effect compared with sinusoidal pulses of the same peak voltage/current. The width of the pulses also influences the stimulation effect. Recent studies in Australia have explored this in some detail and have found that as the pulse width is reduced the effectiveness of ES diminishes slightly, but this reduction can be more than compensated for by an increase in the current. The consequence is that the rms voltage (a function of pulse width, frequency, and peak voltage) increases only slightly, but the effective ES effect is dramatically increased. With low-voltage ES, the greatest DpH values were obtained when the positive electrode was attached to the cranial end of the animal.

Changes in the Rate of pH Fall (dpH/dt) upon Stimulation Almost any stimulation can affect dpH/dt, including unexpected stimulation arising from electrical stunning, immobilization of carcasses, electronic bleeding and even effects from current application during downward hide pulling. Rates of pH fall are slowest in nonstimulated muscles from curarized animals and there are even increases in dpH/dt with any vigorous muscle movement during slaughter. There can be a twofold increase of dpH/dt with stimulation bursts as short as 5 s. Unfortunately, coupled with the other adverse situations in susceptible species such as pork (e.g., stress and nondesirable genetics), a poor outcomes results. Some studies have shown when stimulation is sufficient (in other words a high DpH) this does not occur, but this has not been explored fully. These increases in glycolytic rate can be explained by stimulation causing a reduction in the energy of activation (the amount of energy needed to start the reaction in excess of that already possessed by the molecules). If the activation energy is high, the rate is low and vice versa. The energy of activation (Ea) for the rate of pH fall of nonstimulated muscle has been calculated in a range of situations, with values from 40 to 110 kJ mol−1. In one study for stimulated muscle, the Ea was 70 kJ mol−1 and for nonstimulated muscle from the same animal the Ea was 50 kJ mol−1 suggesting that fundamental changes, perhaps in enzyme activity, are induced by ES. In addition, dpH/dt is strongly affected by temperature, being faster at higher temperatures, so that an increase in temperature (increase in the kinetic energy of the molecules and hence in the rate) has a greater effect on dpH/dt of stimulated muscle than that of nonstimulated muscle. These changes are possibly a consequence of irreversible changes to ATPase activity that dictate the rate of ATP hydrolysis and therefore pH decline. For example, Ca2+-activated actomyosin ATPase activity increases following ES, possibly owing to increased Ca2+ sensitivity, which in turn could account for the lower Ea.

Electrical Stimulation and Hot Boning Hot boning (i.e., the process of boning the carcasses before attainment of rigor mortis in most muscles) has many

Electrical Stimulation

economic advantages (savings in energy, space, labor, and time). The major constraints to the use of hot boning have been the slippage of one muscle relative to another within a primal cut, which is considered visually less appealing, and the extra shortening of excised muscles subjected to rapid chilling. Aging is effective when muscle shortens by less than 20% (but reduces if shortening is greater), so hot boning and aging is feasible if temperatures are controlled. The role of ES in hot-boning applications is clearly to hasten the onset of rigor mortis, so that cold shortening and rigor shortening are minimized. Rapid cooling subsequent to rigor mortis, with its greater control of microbial proliferation, especially in vacuum packaging, can then be used without irrevocably toughening the product. More effective ES is required when very rapid chilling systems are employed. ES by itself cannot prevent cold shortening encountered within rapidly chilled hot-boned meat. In general, hot boning without ES (and also without any prevention of shortening) has resulted in a disproportionately greater increase in the toughness of beef muscles compared to those that are normally stretched when carcasses are supported by the Achilles tendon (e.g., beef m. psoas major). The sarcomere length of cold-boned psoas has been recorded at 3.3 mm (stretched), whereas when hot-boned product it has been fallen to 1.95 mm – close to that of the rest length of most muscles in the body, but further shortening occurs in other muscles. The observation that rigor at approximately 15 °C produces the most tender meat, whether hot-boned or restrained, suggests that further temperature control will result in significant tenderness improvements, but ES still significantly further improves tenderness.

Scientific Basis for Tenderization Involving Electrical Stimulation Rigor Mortis, Cold Shortening, Rigor Contracture Calcium Levels, and Optimum Tenderization If there is sufficient ATP in some fibers, cold shortening can still occur when muscle temperatures fall below 8 °C. A rule of thumb, for the prevention of cold shortening is to maintain temperature above 10 °C until muscle pH falls below 6.0.

Start of Tenderization Proteolysis arising from the action of calpains takes place takes place to a minor extent prerigor, but significant tenderization through cytoskeletal proteolysis commences at rigor mortis, and can continue even in shortened muscle (without the meat becoming tender). If the longissimus muscle has been stretTM ched (e.g., ‘Tenderstretch’ or SmartStretch ), then the beneficial changes due to tenderization occur earlier, but not necessarily to a greater extent. Under the same chilling regimen, stimulated muscles enter rigor mortis and commence to age at a higher temperature than nonstimulated muscles and hence initially experience faster tenderization. Early tenderness measurements will be substantially different for stimulated muscles compared with nonstimulated muscles.

493

Structural Effects Histological images of stimulated muscle have shown on occasion the appearance of contractile bands containing predominantly stretched, ill-defined, and disrupted sarcomeres. The linkage between improved meat tenderness and physical disruption is plausible, as ES treatment has improved tenderness under circumstances where no cold shortening was evident. However, it is unclear whether it is the physical disruption per se that has caused the effect or whether the physical disruption facilitates aging in other ways, such as enhancing proteolysis. Contracture bands are not a direct consequence of electric current passing through the muscle, but are rather due to the supercontracture caused through localized excessive release of calcium ions from the sarcoplasmic reticulum (and also failure by the sarcoplasmic reticulum to pump calcium out). It could be this extra calcium that assists tenderization, since the key proteases are calcium dependent. It is possible that physical stretching/tearing leads to an acceleration of proteolysis as a result of greater exposure of proteolytic substrates within muscle fibers, in addition to the direct effect of physical tearing. Stretched longissimus muscle (Tenderstretch) is initially more tender and the proteolysis starts from this greater tenderness, but the final tenderness is likely to be similar, being limited by connective tissue cross-linking with the final tenderness therefore not being affected. It has been shown that red muscles such as the masseter do not exhibit an increase in rate of pH fall upon ES, but do show evidence of supercontracture. However, white muscles such as the cutaneous are not so susceptible to cold shortening and show almost no supercontracture, yet the rate of pH fall is increased by ES. This raises the question whether structural alteration itself significantly affects meat tenderness of stimulated muscles, whereas there is no direct solid evidence available at the present time to discount the importance of physical alteration.

Impact of Physical Disruption on Ions If the physical disruption is great enough to cause early release of calcium ions from the sarcoplasmic reticulum and mitochondria into the sarcoplasm, this will have a direct effect on activation of the calpain enzyme system and muscle shortening. It has been estimated that free calcium concentration could be raised to more than 100 mmol l−1 by an influx of extracellular calcium ions into the myofibrillar space. However, the evidence indicates that low-voltage ES per se does not lead to an increased release of ‘free’ calcium ions into the sarcoplasm. Calcium concentration in the intracellular space increases during ES, but the released calcium ions are taken back to the resting state into the sarcoplasmic reticulum if energy reserves are not completely depleted during ES treatment. This suggests that at the same temperature, stimulated muscle will be momentarily exposed to higher levels of ‘free Ca2+’ and thus increased proteolysis. Under normal circumstances this extra Ca2+ is sequestered back into the sarcoplasmic reticulum. However, this reuptake process may be retarded if the sarcoplasmic reticulum pumps are affected. In addition, the stimulation accelerates pH decline, which is mirrored by an increase in ‘free’ Ca2+ and consequently an early activation of the tenderization process. Recent studies

494

Electrical Stimulation

have suggested that stimulation irreversibly damages the calcium pump so that it is less efficient at sequestering Ca2+ from the cytosol. This could also give rise to increased proteolysis via calpain system.

Effect of Stimulation on Calpain Enzyme Activity There are several possible explanations why ES might increase the activity of specific enzymes such as the calpains (in addition to being fully available after rigor mortis). It may be due to some intrinsic effect associated with the rapid pH decline, with a low pH at elevated temperatures, that affects the

processes governing the activation and inactivation of the calcium dependent proteases, or it could be due to a flow-on effect associated with a significant increase in ‘free’ calcium, which leads to activation of the calpains, particularly μ-calpain. Because ES alters the postmortem pH–temperature relationship, it is reasonable to expect some effect on endogenous proteolytic enzyme systems (especially the calpain system) and the rate and extent of postmortem proteolysis. In vitro estimations show that the endogenous calpains within skeletal muscle can degrade the myofibril component within an hour, suggesting that ES might confer an advantage to the enzymes responsible for aging at a higher rate of proteolysis in those

Box 3 Clarification of issues relating to ES with questions and answers that explain positive unexpected outcomes from early rigor and early tenderization Issues raised

Answers

Are there any disadvantages of stimulation?

No, other than safety requirements that have to be met. No clear evidence that there are adverse effects in heavy fat carcases No, provided the correct pulse frequencies are used, otherwise there could be resistive heating. Stimulation produces its effect through the muscles doing work and this ceases when the pH falls sufficiently. Thus over stimulation is not possible – it is selflimiting There are a range of frequencies around 12–20 pulses per second. The pulse width can range from 2–10 ms and the stimulation duration must be sufficient to result in a significant pH fall (40+s). The required duration therefore depends on the applied voltages from 80 to 1100 and the time of application after slaughter. See Box 1 for examples Good contact is important for the maximum current to flow. It is this current rather than applied voltage that needs to be standardized and some units are current controlled to ensure reproducible results. More reproducible results ensure if the pelt is removed before stimulation, as contact is better As meat tenderises drip is produced. Drip appears early following stimulation but there is the same drip for the same tenderization No, PSE in pork arises from severe myosin denaturation prerigor and in worst cases a lot of drip is produced because myosin is a major muscle protein. Tenderization occurs via cytoskeletal denaturation postrigor mortis of smaller amounts (o10%) cytoskeletal proteins so no extremes of drip thus not PSE Partially true but not significant. Myosin denaturation will occur to some extent even at low temperatures even without stimulation. Following stimulation rigor occurs rapidly for most muscle fibers and when these are in rigor they are protected from serious adverse effects. The remaining fibers are minimally affected by a brief exposure High-voltage stimulation stimulates the muscle directly. Low-voltage stimulation acts via the nervous system. There are a wide range of useful parameters. Thus the pH falls are not identical. As the voltage rises the duration of stimulation needed to produce optimum effects decreases Only to a small extent. Cold shortening is an issue in small carcasses like sheep when rapidly chilled, but even when cold shortening does not occur meat is still more tender Meat tenderises faster and to a greater extent and therefore customer-ready earlier. The reduction of refrigerated storage capacity required for long aging should lower costs No, stimulation ensures meat is ready for the customer earlier, but this takes the order of days. Chilled storage in transit takes weeks and a day or two earlier does not matter. However, meat tenderises fully following stimulation Has been raised as a theoretical issue, but has not been discernable commercially (other than being more tender) Yes, this may occur with slow cooling but then disappears early during aging No, but it can ensure a given cut reaches its potential tenderness and it might appear to be upgraded compared with unsatisfactory processing Without stimulation there can be significant tenderness differences between breeds, but with stimulation this difference largely disappears and both are more tender than without stimulation

Can there be too much stimulation?

What are the optimum stimulation parameters?

How important is contact?

What is the effect of stimulation on drip? Can stimulation produce a PSE-like condition?

Following stimulation the temperatures are high and pH low and myosin denaturation could occur

What is the difference between high- and low-voltage stimulation?

Does stimulation work mainly through reducing cold shortening? What is the main advantage of stimulation? Are there disadvantages with long storage following stimulation? Are there texture differences through stimulation? Can a heat ring occur? Can stimulation upgrade cuts? Does stimulation affect some breeds more than others?

Electrical Stimulation

muscles. ES however, does not appear to have a role in activation of lysosomal enzymes under normal chilling conditions.

Unclear Interpretations of Stimulation Effects ES is often regarded as a variation to normal meat processing – merely enhancing entry into rigor mortis and avoiding cold shortening, but this is only partially true. Without ES, problems with prolonged high rigor temperature cause both myosin protein denaturation and reduced aging – this does not appear to occur to the same extent with electrically stimulated muscles where similar exposure to high rigor temperatures are brief. Extrapolations from unstimulated to stimulated systems are therefore problematic as the two situations are not comparable as mentioned above. Even so, in some experimental studies without chilling it appears that even with ES, prolonged prerigor temperatures above 38 °C may inhibit tenderization to a minor extent. Adverse effects of ES appear to be rare and many controversial issues arise possibly arising from ineffective ES with poor chilling (hence the emphasis on optimum ES parameters and optimum chilling above) or not measuring comparable indices at equivalent times. The implication that ES increases total drip appears misplaced, for example, and experimental evidence is either unclear, minor, or is not supported. The preand postrigor sources of drip therefore need to be explored in more detail to characterize this situation fully. As overall muscle responsiveness ceases when the pH falls to approximately 6.3 during ES, it is physiologically not possible to over stimulate as muscles cannot respond. Although ES is necessary where cold shortening is an issue, several studies show that ES also ensures the greatest possible tenderness. Elevated rigor temperatures in the absence of ES inhibit tenderization at the end of aging. Although early tenderness levels may be superior, final tenderness may not reach the levels for meat entering rigor at lower temperatures – thus without ES it is necessary to cool carcasses to temperatures where maximum tenderization occurs. The Meat Standards Australia (MSA) temperature window for optimum chilling was designed with this in mind. For other classes of carcasses (lambs/sheep and lighter beef) ES is needed to achieve the relevant MSA temperature/pH windows. Is ES effective for pork? With optimum ES the answer is sometimes unexpectedly yes for some breeds. Other very stress-susceptible breeds such as Pietrain do not give good results. Surprisingly when successful, problems of excess drip do not appear to arise (other than as the expected consequence of tenderization). Insufficient ES, however, appears to set in place conditions that result in PSE as mentioned above. In the case of unstimulated poultry, fast rigor entry and subsequent aging is normally rapid. An even faster rigor entry after ES allows wing removal, breast to be trimmed and portioning early without rigor toughening (adverse rigor effects seem to be more severe in poultry than other meats) in approximately 1 h without quality deterioration.

Conclusion It is clear that ES improves meat quality and there are no clear disadvantages with proper chilling (Box 3), and optimization

495

of parameters produces significantly better results. This improvement is maximized when meat is rapidly chilled to reach temperatures close to 15 °C and some advantages are summarized in Box 2, for tenderness, color and color stability. However, ES does not significantly improve inherently tender meat beyond baseline tenderness and cannot improve on the toughness associated with intemediate pH meat (i.e., ultimate pH 5.8–6.2) or improve upon the tenderness achieved from procedures such as Tenderstretch. Drip that appears is a consequence of degradation of cytoskeletal proteins during aging appears earlier for the same level of tenderization with or without ES. Although ES of carcasses hastens the onset of rigor mortis and reduces cold-induced shortening and toughness, there can be other effects such as early activation of the calpain system, possibly involving elevation of calcium at critical times, which can hasten cytoskeletal protein degradation and generally positively contribute to tenderness, with concomitant fiber disruption potentially contributing. Because ES alters the postmortem pH–temperature relationship it is reasonable to expect some effect on endogenous proteolytic enzyme systems (primarily the calpain system) and subsequently the rate and extent of postmortem proteolysis and enhancement of the activity of the enzymes responsible for aging by the elevated temperatures that exist at that time.

See also: Carcass Chilling and Boning. Chemical and Physical Characteristics of Meat: Color and Pigment; Palatability; pH Measurement; Water-Holding Capacity. Connective Tissue: Structure, Function, and Influence on Meat Quality. Conversion of Muscle to Meat: Aging; Color and Texture Deviations; Glycolysis; Rigor Mortis, Cold, and Rigor Shortening. Cutting and Boning: Hot Boning of Meat. Exsanguination. Measurement of Meat Quality: Measurements of Water-holding Capacity and Color: Objective and Subjective. Modeling in Meat Science: Meat Quality; Refrigeration. Muscle Fiber Types and Meat Quality. Refrigeration and Freezing Technology: Applications; Equipment; Freezing and Product Quality; Principles. Sensory and Meat Quality, Optimization of. Slaughter-Line Operation: Cattle; Sheep and Goats. Stunning: Electrical Stunning; Slaughter: Immobilization. Tenderizing Mechanisms: Chemical; Enzymatic; Mechanical. Tenderness Measurement

Further Reading Chrystall, B.B., Devine, C.E., 1978. Electrical stimulation, muscle tension and glycolysis in bovine sternomandibularis. Meat Science 2, 49–58. Devine, C.E., Ellery, S., Averill, S., 1984. Responses of different types of ox muscle to electrical stimulation. Meat Science 10, 35–51. Devine, C.E., Wahlgren, N.M., Tornberg, E., 1999. Effect of rigor temperature on muscle shortening and tenderisation of restrained and unrestrained beef m. longissimus thoracis et lumborum. Meat Science 51, 61–72. Ferguson, D.M., Jiang, S.-T., Hearnshaw, H.R., Rymill, S.R., Thompson, J.M., 2000. Effect of electrical stimulation on protease activity and tenderness of M. longissimus from cattle with different proportions of Bos indicus content. Meat Science 55, 265–272. Gursansky, B., O'Halloran, J.M., Egan, A., Devine, C.E., 2010. Tenderness enhancement of Bos indicus and Bos taurus cattle through electrical stimulation. Meat Science 86, 635–641.

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Hopkins, D.L., 2011. Processing technology changes in the Australian sheep meat industry: An overview. Animal Production Science 51, 399–405. Hwang, I.H., Devine, C.E., Hopkins, D.L., 2003. The biochemical and physical effects of electrical stimulation on beef and sheep meat tenderness − A review. Meat Science 65, 677–691. Jeacocke, R.E., 1977. The temperature dependence of anaerobic glycolysis in beef muscle held in a linear temperature gradient. Journal of the Science of Food Agriculture 28, 551–556. Jeacocke, R.E., 1984. The kinetics of rigor onset in beef muscle fibres. Meat Science 11, 237–251. Offer, G., 1991. Modelling of the formation of pale, soft and exudative meat: Effects of chilling regime and rate and extent of glycolysis. Meat Science 30, 157–184.

Pearce, K.L., van de Ven, R., Mudford, C., et al., 2010. Case studies demonstrating the benefits of optimising medium voltage electrical stimulation of lamb carcases. Animal Production Science 50, 1107–1114. Rosenvold, K., North, M., Devine, C.E., et al., 2007. The protective effect of electrical stimulation and wrapping on beef tenderness at high pre rigor temperatures. Meat Science 79, 299–306. Strydom, P.E., Frylinck, L., Smith, M.F., 2005. Should electrical stimulation be applied when cold shortening is not a risk? Meat Science 70, 733–742. Taylor, A.A., Tantikov, M.Z., 1992. Effect of different electrical stimulation and chilling treatments on pork quality. Meat Science 31, 381–395. Toohey, E.S., Hopkins, D.L., Stanley, D.F., Nielsen, S.G., 2008. The impact of new generation pre-dressing medium-voltage electrical stimulation on tenderness and colour stability in lamb meat. Meat Science 79, 683–691.

ENVIRONMENTAL CONTAMINANTS

M Rose, The Food and Environment Research Agency, Sand Hutton, York, UK r 2014 Elsevier Ltd. All rights reserved.

Introduction Environmental contaminants arise in meat as a result of chemicals present in the areas where the food is produced and from the use of contaminated animal feeds in the production process. Most organic contaminants arise initially as a result of industrial processes combined with the properties of the compounds themselves in that they persist in the environment as a result of their chemical stability and other physicochemical properties. These compounds are termed persistent organic pollutants (POPs). Elements and some radionuclides may also be present as a result of the geology and geography of the regions where the animals, birds, or fish are farmed or produced, combined with the location of production and type of feed ingredients used. Stable environmental contaminants may also be resistant to metabolism in plants or animals, and this can lead to bioaccumulation as higher trophic levels of the food web are reached. Because fish are at or close to the top of the aquatic food chain, and farm animals are similarly placed in the terrestrial food chain, levels of these persistent ubiquitous contaminants can accumulate in the tissues of fish and meat-producing animals. Where meat and fish by-products are used for animal feed, there is further scope for the elevation in levels of these compounds, unless they can be removed during processing.

Pesticides Residues of pesticides are more commonly associated with foods of plant origin than with meat and other food products of animal origin. Nevertheless, there is the potential of residues arising, for example, from the use on animals of insecticides, such as organophosphates, pyrethroids, and carbamates; however, these are rapidly metabolized and therefore unlikely to be found in high concentrations or long after application. Some pesticides are classed as POPs and hence residues of them can be found in the environment and can also be present in animal feed ingredients, for example, cocoa bean husks. The occurrence of organochlorine residues in cows' milk produced in countries where the organochlorine pesticides have not been used for some years may be attributed to the use of contaminated animal feed or animal feed ingredients imported mainly from less developed countries where the pesticides are still in current use. Such pesticides include dichlorodiphenyltrichloroethane (DDT), lindane (hexachlorocyclohexane, γHCH) and other HCHs, hexachlorobenzene (HCB), aldrin and dieldrin, chlordane, etc. together with their degradation

Encyclopedia of Meat Sciences, Volume 1

products and metabolites. In more developed countries, the application and use of pesticides is legally controlled in such a way that residue levels occurring in food are minimized. Where they are used according to good agricultural practice, residues of these pesticides should not exceed maximum residue levels (MRLs), which are set on the basis of what is achievable by best practice, i.e., correct application rates and minimum harvest intervals. Most of the more developed countries have in place monitoring programs to examine both home-produced and imported food; although the emphasis of these programs is directed toward foods of plant origin, there is a significant level of monitoring of animal and fish products. The number of MRL exceedences in fruits and vegetables is typically a few per cent (usually between 3% and 5%), whereas the number of violations for meat and animal products is generally well below 1%. Persistent pesticides may also be found in aquatic systems. They may arise from direct use in wetlands where they may be used to control vector insects (e.g., DDT has been used to control the spread of malaria by mosquitoes) and may also be used in fish farming (e.g., some organophosphates are used to control sea lice infections of farmed salmon). Pesticides, especially herbicides, can also enter river systems as a result of rainwater and irrigation wash-off from agricultural land into rivers. The potential for these compounds to biomagnify and to accumulate in fish and other aquatic fauna is strong. The residues will reenter the land-based food chain if fish are eaten by wildlife or are caught for human consumption. The organochlorine pesticides are highly lipophilic and can quickly accumulate in oily fish. There have been particular problems with eels caught in river estuaries, partly because of their oily nature and longevity and also because of the environments they inhabit.

Toxaphene Toxaphene, or camphechlor, is a complex mixture of polychlorated bornanes (CHBs) and other camphenes. It was one of the most heavily used chlorinated pesticides in the world, with the total quantities used estimated in megatonnes, which is comparable to the usage of polychlorinated biphenyls (PCBs) (see Section Dioxins and Polychlorinated Biphenyls). Toxaphene has been shown to undergo long-range transport and is recognized as a ubiquitous environmental contaminant. Like other organochlorine pesticides, it has also been shown to bioaccumulate in aquatic organisms. Human exposure comes largely from human milk – for breast-fed infants (especially if the mother has been eating a diet rich in oily fish) – fish, and

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seafood. Although toxicological data are scant, toxaphene is a probable carcinogen and is a known endocrine disruptor. Owing to weathering and biotransformation, the residue composition in food of marine or animal origins will not necessarily reflect the original pesticide mixtures used.

Dioxins and Polychlorinated Biphenyls Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) (collectively referred to as ‘dioxins’) arise as a result of combustion processes, as by-products in the manufacture of organochlorine compounds, or as a result of activity of the chlorine industry. They are chemically stable and are ubiquitously present in human tissues, even when there is no history of occupational or accidental exposure. Although exposure could occur through inhalation of air, dermal absorption, consumption of drinking water, and consumption of food, the last is the predominant route for the general population and accounts for more than 90% of human exposure. Although there are a total of 210 dioxins, only the 17 laterally substituted congeners, i.e., those that contain chlorine at the 2, 3, 7, and 8 positions persist and accumulate in animal tissues. These congeners form only a small proportion of the total output from many sources and environmental pollution. These 2-, 3-, 7-, and 8-substituted congeners are regarded as significantly toxic and have thus been the main focus of most exposure studies. They are highly lipophilic and are thus found primarily in fatty tissues, such as human and animal fats and fish oils. PCBs are a group of compounds that were manufactured until the 1980s for use in various ways, including electrical products (e.g., as a dielectric in transformer oil). They are ubiquitous environmental pollutants, and it has become widely accepted that some PCBs elicit dioxin-like biochemical and toxic responses. These are the coplanar PCBs, i.e., those with no or only one ortho substituent. Assessment of the health risks of exposure to dioxin-like chemicals must, therefore, consider these PCBs in addition to the dioxins. The amount of information pertaining to dioxin-like PCBs in foods is somewhat less than for PCDDs/PCDFs themselves but is growing rapidly. However, PCBs have a variety of other biological effects, and although consideration of ‘dioxins’ is incomplete without the inclusion of dioxin-like PCBs, the different types of toxic effects of these and other PCBs should be taken into account. Because of their toxicity, both dioxins and dioxin-like PCBs need to be measured at extremely low concentrations in food, and the sum of dioxins and dioxin-like PCBs present is usually expressed in picograms (1 pg ¼ 10−12 g) of dioxins (as toxic equivalents to the most toxic 2,3,7,8-tetrachloro dibenzo-pdioxin (TCDD)) per gram of food. Analysis at these concentrations is technically extremely challenging and expensive and is probably the most complex chemical analysis that is carried out as part of regular monitoring programs. The majority of PCB analyses are carried out by gas chromatography using more routine methods, but these often do not measure the dioxin-like PCBs, which are present at much lower concentrations in the environment than other congeners.

In addition to the general environmental contamination from dioxins and PCBs, there have been specific isolated events that have resulted in the release of these compounds into the environment and hence to their incorporation into food within a localized area. Such incidents have included the accident in Seveso in 1976, when a manufacturing plant producing a chlorinated herbicide exploded, scattering several kilograms of 2,3,7,8-TCDD (the most toxic of the dioxins) around the immediate locality of the factory; the spraying of contaminated ‘Agent Orange’ herbicide (2,4,5trichlorophenoxyacetic acid) in Vietnam in the 1960s conflict in order to defoliate the jungle; the Yusho- and Yu-chengcontaminated rice oil incidents in Japan and Taiwan, respectively; and the contamination of animal feed with transformer oil containing PCBs and (to a lesser extent) dioxins in Belgium in 1999. In 2008, animal feed derived from waste food contaminated by dioxins in heating oil used to dry the feed was supplied to 7 pork producers and 38 cattle farms in Ireland, resulting in a recall of all Irish domestic pork and pork products that had been exported to 23 countries.

Tolerable Intake In 1990, the WHO established a tolerable daily intake (TDI) of 10 pg per kg body weight (bw) for 2,3,7,8-TCDD, but in 1998, an expert consultation concluded that the TDI should include other dioxins and PCBs that exhibit a similar toxic effect. The concentrations of the toxic congeners were weighted according to their toxicity using Toxic Equivalency Factors (TEFs) to give units expressed as toxicity equivalents (WHO-TEQs) and were established as a range of 1–4 pg WHO-TEQ per kg bw per day. The concept of TEFs was developed to facilitate risk assessment. These TEFs have been established to express concentrations of mixtures of 2,3,7,8substituted PCDDs and PCDFs and some nonortho and monoortho chlorine-substituted PCBs that possess dioxin-like activity in toxic equivalents (TEQs) of 2,3,7,8-TCDD. Concentrations of the individual substances in a given sample are multiplied by their respective TEF and subsequently summed to give the total concentration of dioxin-like compounds expressed as a TEQ. TEQ ¼ ∑½PCDDi  TEFi  þ ∑½PCDFi  TEFi  þ ∑½PCBi  TEFi 

More recently, at the end of May 2001, the Scientific Committee on Food (SCF), an expert committee that advises the European Commission, decided that the tolerable intake should be expressed on a weekly rather than a daily basis and set a tolerable weekly intake (TWI) of 14 pg WHO-TEQ per kg bw per week. The WHO/FAO Joint Expert Committee on Food Additives (JECFA) established, in June 2001, a provisional tolerable monthly intake (PTMI) of 70 pg WHO-TEQ per kg bw per month. Current estimates of consumer exposure show that intake of dioxins and dioxin-like PCBs is between 1.2 and 3 pg WHO-TEQ per kg bw per day, which is a range that overlaps with the range of the recommended limits. It is, therefore, important that steps are taken to reduce the amount of these substances found in food by the implementation and enforcement of pollution control measures.

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Legislation Although regulatory limits for dioxins in food have been set on an ad hoc basis by various authorities in the past, the European Union (EU) became the first body to set extensive and comprehensive limits for these compounds. These EU regulations came into force in July 2002, and include limits for PCDDs/PCDFs in food and animal feed. There was a stated intention to revise these limits with a view to making them stricter before the end of 2004. In 2005, the WHO reevaluated the weightings given to individual dioxin and PCB congeners and produced a revised set of toxic equivalence factors (TEFs) to use when calculating the TEQ. New EU limits were eventually proposed in 2011 and came into force on 1 January 2012. They use the new TEF scheme and have been lowered for some food types. An additional set of limits for the nondioxin like PCBs was also introduced, based on the sum of six marker PCB congeners. Mandatory targeted testing for animal feed has been proposed.

Concentrations in Meat and Fish Because PCDDs/PCDFs and PCBs are lipid soluble, for most food types containing more than approximately 2% fat, the concentrations found are reported on a fat-weight basis rather than on a whole-product basis. This gives more consistency for comparisons of samples containing variable concentrations of fat, such as dairy products, which show more variability with respect to dioxins on a whole-weight basis than on a lipid basis. For some samples, however, reporting on a fat-weight basis may lead to confusion. Fish can show large seasonal variations in fat content, which can result in an illusion of variation, even if the body burden with respect to dioxins remains constant. As pollution control measures are introduced and come into effect, levels of dioxins and PCBs in meat have started to show a downward trend. The same is true, but to a lesser extent, for fish. Most available data suggest that mean dioxin levels on a fat basis in pork in most cases are lower than for beef, poultry, or mutton; concentrations on a fat basis in animal livers are higher than in other tissues for the same species. There is a widespread data reported for fish, probably because of the large number of species, and also the geographical differences in the levels of contamination in the various fishing grounds from which the fish originate. Typically, many species of white fish contain lower levels than oily fish species and some shellfish species. This is especially true when sourced from a relatively highly polluted area. Certain fish species originating from the Baltic region are recognized as containing high concentrations of PCDDs/PCDFs and PCBs. A significant proportion of fatty fish from this region, such as Baltic herring and Baltic salmon, are unlikely to comply with the EU limit for dioxins, and these fish would, therefore, be excluded from the Swedish and Finnish diets. There are indications that such an exclusion would have a negative health impact in Sweden and Finland due to the nutritional importance of omega-3 fatty acids, vitamin D, and other ingredients in the fish, some of which are especially beneficial in low-light countries.

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Consequently, there is a local exemption to compliance with this legislation. Sweden and Finland have in place a system that informs consumers of the dietary recommendations about the consumption of fish from the Baltic region, in order to avoid possible health risks. Another source of dioxins in meat can be from pentachlorophenol (PCP)-treated wood (for preservative purposes) used to house farm animals and poultry. PCP can contain traces of dioxins in a characteristic congener profile, and there have been incidents when this was thought to account for the elevated contaminant levels found in meat. How do these become residues in meat? It says above that: “They are POPs and behave in the environment in a similar way to the dioxins and PCBs.”

Trace Elements The main sources of metals and other elements in food come from the environment. Some of these, such as arsenic, can be endogenous in some circumstances (e.g., in Bangladesh, where there is groundwater contamination), whereas others, such as lead, normally arise as a result of pollution from industry and other human activities. Elements can also arise in food as a result of certain agricultural practices; for example, cadmium from impure or contaminated phosphate fertilizers can pollute farm land. Manufacturing processes are also potential sources of contamination; for example, tin can be introduced to the food supply from the canning process. It is also possible to introduce trace metals during food preparation when metals, glazed ceramics, or enameled utensils are used. Trace elements are of interest because of their possible health effects. Unlike the other categories in this section, some of the elements such as iron and calcium have health benefits. Others have no known beneficial biological functions and long-term high-level exposures may be harmful to health. Elements in this class include mercury in organic mercury compounds, which are known neurotoxins; lead, which can impair neuropsychological development; inorganic arsenic, which is an acute poison and a human carcinogen; and cadmium, which can cause kidney failure. High levels of tin can cause acute abdominal problems. Many metals such as copper, chromium, selenium, and zinc are essential to health at appropriate levels but become toxic at higher levels of exposure. Toxicity and bioavailability of trace elements can depend on the form in which they are present in food. For example, organic forms of mercury, such as methyl mercury, are much more toxic than inorganic elemental mercury. In contrast, it is the inorganic form of arsenic that is more toxic than the organic compound forms, such as arsenobetaine. Trace elements are assessed for safety by comparing dietary intake estimates with recommended safe levels. The figures usually used are the provisional tolerable weekly intake (PTWI) values and provisional maximum tolerable daily intake (PMTDI) values as recommended by the FAO/WHO Joint Expert Committee on Food Additives. These are estimates of the amount of a substance that can be ingested on a weekly or daily basis over a lifetime without any known risk to health. Some of the routes of the largest exposure to toxic trace elements, especially mercury and arsenic, are from fish and

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shellfish that can bioaccumulate these contaminants from polluted waters. Fish can take up mercury from marine sediments, and fish and farm animals can be exposed as a result of pollution from industrial emissions. The high exposure of human populations that consume large quantities of fish to mercury has led to interest in the neurological development of children from such areas, for example, Faeroe Isles and Republic of Seychelles. Similarly, arsenic and aluminum may be found at elevated concentrations in fish. Other elements, such as copper, lead, and cadmium, may be found at higher levels in offal, although this is generally eaten in relatively small amounts and exposure to toxic elements from this source is, therefore, still small for most segments of the population. Concentrations of lead in meat and other foods are following downward trends because of measures to reduce lead in the environment in recent years following the introduction of a number of important pollution control measures, such as the move to unleaded fuel for motor vehicles and unleaded paints.

Radionuclides Natural and artificial radioactive elements can be found in food. Both types normally enter the food chain as a result of general environmental contamination. Like their nonradioactive counterparts, deposition from the atmosphere or from contaminated water results in direct exposure for farm animals or can result in uptake from contaminated soil or surface deposition onto plants that are, in turn, consumed by farm animals and result in contamination of meat.

Natural Radioisotopes Three different types of natural radioactive elements can occur in food. The first are those that have always been in the lithosphere and have half-lives measured in millions of years, such as uranium 238, thorium 232, and potassium 40. The second group is composed of daughter elements resulting from the disintegration of the longer life parent elements. Radium 226, produced from uranium 238, is an example of this type. Radium, in turn, can decompose to produce radon, which is also unstable and can generate lead 210 and polonium 210. The third group consists of isotopes formed by the action of cosmic rays in the atmosphere. An important product generated in this way is carbon 14, made by the transmutation of nitrogen. Natural radioisotopes account for approximately a quarter of the total background dose of radiation to which one is exposed.

Artificial Radioisotopes Artificial radioisotopes that can be found in food increased greatly following the explosion of the Hiroshima bomb in 1946. Increases were also particularly rapid during the 1960s, when the nuclear powers carried out many atmospheric tests. In addition, smaller amounts of artificial radioactivity are released into the environment by nuclear power stations and their associated plants that process the waste materials.

A still smaller contribution arises from medical and research uses. When an atomic bomb explodes or a nuclear reactor operates, a mixture of radioactive elements is produced from heavy isotopes such as uranium 235 and plutonium 239. Lighter radioactive isotopes may be produced as a result of fission, such as strontium 90 (half-life 28 years), cobalt 60 (half-life 5.3 years), ruthenium 106 (half-life 1 year), cesium 137 (half-life 30 years), and iodine 131 (half-life 8 days). There are also various activation products, including zinc 65 (half-life 245 days) and carbon 14 (half-life 5760 days). Activation products are not produced directly by the fission process but are produced alongside as a result of the action of atomic radiation, especially neutrons, on elements naturally present where the reaction occurs. Elements used in medicine, industry, and research can also be produced by a process of neutron bombardment of selected target atoms in specially designed reactors. In addition to environmental levels, the relative uptake of radioactive isotopes is an important consideration when considering food and meat contamination. Plutonium can be extremely hazardous when directly ingested, but plants take up plutonium compounds only with difficulty. Its salts are less soluble than those of cesium or strontium, so it is unlikely to enter the food chain in significant quantities by this route. Surface contamination of plants and direct ingestion are of greater concern for this type of element. Nuclear reactors can result in the contamination of seas and rivers by the discharge of low-level waste or by accidental release into either the atmosphere or the aquatic ecosystem. Some forms of marine life can concentrate cesium 137 and other radioactive isotopes in their tissues, as they do with some nonradioactive isotopes. Flatfish concentrate this isotope by a factor of 20 compared with surrounding seawater concentrations. Zinc 65 has been found to bioaccumulate in the flesh of oysters near the discharge pipes of nuclear power stations. Monitoring programmes for radioactivity in food place a large emphasis on fish and marine products because of this possibility, although so far no serious concern to health with regard to biomagnification of these isotopes has been identified.

Incidents Resulting in the Contamination of Food with Radionuclides Chernobyl The world's worst nuclear power accident occurred at Chernobyl in the former USSR (now Ukraine) in April 1986. A reactor at the Chernobyl nuclear power plant, located 80 miles north of Kiev, went out of control, creating a chain reaction that resulted in explosions and a fireball that blew off the reactor's heavy steel and concrete lid, releasing a large radioactive cloud into the atmosphere. The Chernobyl accident killed more than 30 people immediately, and as a result of the high radiation levels in the surrounding 20-mile radius, 135 000 people had to be evacuated. Levels of radioactivity resulting from the explosion are still unexpectedly high and are expected to remain so for another 50 years. Levels of radioactivity found in fish caught from lakes

Environmental Contaminants

in the UK and Norway, and in lambs grazing on upland hills, were found to be unexpectedly high after the incident owing to contamination, particularly with cesium 137. During the first 5 years following the accident, concentrations of this radioactive element in most foodstuffs and water decreased by a factor of 10, but since then, the rate of decrease appears to have slowed down. At the end of 2011, the UK Government proposed to remove all remaining controls on the movement of sheep from the restricted areas, based on the assessment that the risk to consumers from radioactivity in sheep meat resulting from the Chernobyl nuclear accident is now very low. Berries, mushrooms, and fish from some areas of the former Soviet Union are more likely to continue to be restricted from sale for some years, and fish from some lakes, such as Lake Kozhanovskoe, are thought to remain under restriction for approximately another 50 years.

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adverse health effects in experimental animals. But any risk assessment should form part of a risk-benefit analysis and many of the foods that contribute significantly to the source of these contaminants, such as oily fish, also have many health benefits associated with their consumption. Pollution control measures together with efforts to regulate food contaminants in some parts of the world have resulted in a reduction in the amounts of some of these contaminants in food over recent years.

Disclaimer The views expressed in this article are those of the author and do not necessarily represent the opinions or policies of the UK Department for Environment, Food and Rural Affairs.

Fukushima On 11 March 2011, an earthquake of magnitude 9.0 hit off the northeast coast of Japan. The subsequent tsunami struck the Fukushima nuclear power plants and radionuclides were released into the environment. As part of the risk management process, provisional regulation measures for radionuclides in foodstuffs were taken. For radiocesium, uranium, plutonium, and transuranic α emitters, these limits were set to keep the committed effective dose (an estimate of the radiation dose to a person resulting from inhalation or ingestion of a given amount of radioactive substance) less than 5 mSv year−1. For radioiodines, they were set to keep the committed equivalent dose to the thyroid less than 50 mSv year−1. Tap water, raw milk, and some vegetables were the first foodstuffs found to be contaminated, but fish with radionuclides above levels of concern were detected soon afterward. Meats, including beef, did not generally exceed the provisional regulation value for radiocesium, but measures were taken to insure that farm animals did not graze in the affected area and were not given contaminated feed. As a result of the incident, it was possible to detect low levels of radionuclides in foods produced around the globe, but the major impact was on food produced around the plant. Many countries placed restrictions on the import of food from Japan. A massive program of monitoring was brought into effect by the Japanese authorities and, at the time of writing, restrictions are still in place.

Note Environmental contaminants might be associated with specific incidents but many classes are ubiquitous within the environment and are present in all of the food we eat. The concentrations of many of these contaminants in food are very low, and we should be reminded of the work of Paracelcus who lived from 1493 to 1541 and taught us that ‘the dose makes the poison.’ Having said that, although the concentrations of these contaminants might be very small (e.g., a few parts per trillion or even quadrillion for dioxins and similar organic contaminants), these concentrations in foods give rise to exposure close to the levels shown to give rise to

See also: Canning. Chemical Analysis: Analysis of Final Product Composition for Labeling; Raw Material Composition Analysis; Sampling and Statistical Requirements. Chemical Analysis for Specific Components: Curing Agents; Major Meat Components; Micronutrients and Other Minor Meat Components. Hazard Analysis Critical Control Point and Self-Regulation. Human Nutrition: Cancer Health Concerns; Macronutrients in Meat; Micronutrients in Meat; Vegetarianism. Microbiological Analysis: Standard Methods. Residues in Meat and Meat Products: Feed and Drug Residues; Residues Associated with Meat Production

Further Reading Allsop, M., Erry, B., Stringer, R., Johnston, P., Santillo, D., 2000. A Review of Persistent Organic Pollutants in Food UK: Greenpeace Research Laboratories, University of Exeter. ISBN: 90−73361−63−X. Annual Report of the Working Party on Pesticide Residues, 1992. Supplement to the Pesticides Register 1993. London: HMSO. Available at: http://www.pesticides.gov. uk/committees/PRC/ (accessed 24.03.03). Ebdon, L., Pitts, L., Cornelis, R., et al., 2001. Trace Element Speciation for Environment, Food and Health. London: Royal Society of Chemistry. European Commission Task 3.2.5. Brussels, 2000. Assessment of dietary intake of dioxins and related PCBs by the population of EU Member States. Reports on tasks for scientific co-operation. Available at: http://europa.eu.int/comm/dgs/ health_consumer/library/pub/pub08_en.pdf (accessed 24.03.03). Hamada, N., Ogino, H., 2012. Food safety regulations: What we learned from the Fukushima nuclear accident. Journal of Environmental Radioactivity. doi:10.1016/ j.jenvrad.2011.08.008. Radioactivity in Food and the Environment, RIFE-7 (and previous and later editions). Compiled by the Centre for Environment, Fisheries and Aquaculture Science (CEFAS) on behalf of the Food Standards Agency and the Scottish Environment Protection Agency (SEPA). Available at: http://www.google.co.uk/url? sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CC4QFjAA&url=http%3A %2F%2Fwww.sepa.org.uk%2Fradioactive_substances%2Fpublications%2Fidoc. ashx%3Fdocid%3D59116ab2-635e-4ee6-b96f-90b1287cb5c2%26version%3D1&ei=PGlhUqTKA8Oh0QXVh4CADg&usg=AFQjCNEwga8dWV59XG7 yaoZAGH3nrAoVZA&sig2=io87—1lxkoJmc2yN7mJg&bvm=bv.54176721,d. d2k&cad=rja (accessed 18.10.13). Schecter, A., Gasiewicz, T.A., 2003. Dioxins and Health, second ed. New York: Wiley. Sheppard, C., (Ed.), 2000. Seas at the Millenium: An Environmental Evaluation. Oxford: Elsevier Science.

ENVIRONMENTAL IMPACT OF MEAT PRODUCTION

Primary Production/Meat and the Environment C Cederberg, Chalmers University of Technology and SIK–the Swedish Institute for Food and Biotechnology, Gothenburg, Sweden r 2014 Elsevier Ltd. All rights reserved. This article is a revision of the previous edition article by GJ Monteny, volume 1, pp 424–430, © 2004, Elsevier Ltd.

Glossary CH4 Methane. CO2 Carbondioxide. GHG Greenhouse gas. GWP Global warming potentials. Glyphosate (Common commercial trade-name roundup) Is the most used herbicide in the world. It is a broadspectrum and nonselective herbicide.

Introduction In 2007, global meat production was close to 280 million ton (Mton), corresponding to approximately 40 kg meat per person as a global average, of which pork dominated with approximately 40% of total supply followed by poultry representing approximately 30% (Figure 1). For the past 20 years, production from mono-gastric animals has expanded much faster than from ruminants, and also milk production has had a smaller growth rate than pig and

Mton Million ton. N2O Nitrous oxide. N Nitrogen. P Phosphorus ppb Part per billion.

poultry. According to reports from the Food and Agriculture Organization (FAO), the demand for animal products is predicted to double by 2050 relative to a year 2000 baseline. The FAO report ‘Livestock's Long Shadow’ highlighted the environmental impacts of the fast-growing global livestock sector and this issue has gained a lot of attention in society over the past years. Recently, also dietary shifts, reducing overall intake of animal products in high-income countries, are increasingly discussed as a necessary mitigation option.

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Figure 1 Global production of meat and eggs, 1987 and 2007. Reproduced from FAO, 2009. The state of food and agriculture – Livestock in the balance. Available at: www.fao.org/docrep/012/i0680e/i0680e.pdf (accessed 20.01.14).

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Environmental Impact of Meat Production | Primary Production/Meat and the Environment This article gives a short overview of the most important environmental aspects of livestock production: effects of land occupation and land conversion, interference in nitrogen and phosphorus cycle, emissions of greenhouse gases, and use of chemicals, and it is suggested that solutions must be found in both production and consumption phase of animal products.

Impacts Related to Land Use The livestock sector today occupies approximately 30% of the global land surface and is thus the largest anthropogenical use of land. Approximately one-third of total arable land is dedicated for feed crop cultivation and in all, livestock production accounts for 70% of all agricultural land on the planet according to ‘Livestock's Long Shadow.’ The expansion of agriculture over the past 200 years has been dramatic, in 1750, total agricultural land was less than one billion hectare and this has increased almost fivefold in only 200 years. Agricultural expansion has had an enormous impact on habitats, biodiversity, carbon storage, and soil conditions such as erosion and organic matter. Globally agriculture has already converted 70% of grasslands, 50% of savanna, 45% of temperate deciduous forests, and 27% of tropical forests. Expansion of livestock production is a key factor in deforestation, especially in South America where approximately 70% of deforested land is occupied by pastures and feed crops (mainly soybeans) cover a large part of the remainder.

Biodiversity One of the most direct drivers of biodiversity loss is land use change. Examples of this is conversion of temperate grasslands into arable land, or tropical forests into pastureland resulting in local extinction of most plant species and the associated animals whose habitat is largely determined by the composition of plant species. According to the Millennium Assessment, over the past few hundred years, humans have increased species extinction rates by as much as 1000 times over background rates that was typical in Earth's history. Because future scenarios predict that further 10–20% of grasslands and forestlands are projected to be converted mainly into agriculture by 2050, the impact of livestock's land requirement for feed and fodder production on biodiversity losses must be better understood and dealt with. Rapidly growing demand for meat is the most important driving force for expansion of soybeans in South America. In Brazil, much of the soybean expansion has taken place in the cerrado biome where more than half of approximately 200 million hectare has been transformed into pasture with monoculture grass species and cropland in the past 35 years. The cerrado biome has the richest flora among the world's savannas and high levels of endemism (species not found elsewhere in the world). Deforestation rates have been higher in the cerrado than in the Amazon rainforest, and conservation efforts have been modest: only 2.2% of its area is under legal protection. Numerous animal and plant species are threatened with extinction.

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Effects of livestock on biodiversity in Europe are described in a report from the Joint Research Centre of the EU Commission, investigating greenhouse gas (GHG) emissions and other impacts from European animal agriculture. Agricultural intensification has resulted in homogenization of large areas of European rural landscape. Of special importance to livestock production is farming system specialization (livestock vs. arable) with the loss of mixed farming system, larger farming units leading to removal of noncropped areas and field boundaries. But there are also positive impacts of cattle, the biodiversity in European seminatural grassland is very high and their management is dependent on grazing livestock. Very large proportions of Europe's most threatened bird species, vascular plants, and insects live in these grasslands and other ‘high nature value farmland.’

Impacts Related to Nutrient Use Mismanagement of nutrients in primary livestock production is the major reason for the large negative human interference with the global nitrogen (N) and phosphorus (P) cycles and this is informatively described in research papers of Erisman et al. (2008) and Cordell et al. (2009). In 2005, more than 100 Mton synthetic fertilizer-N and N in leguminous plants were an input in global agriculture whereas only 17 Mton N was consumed by humans in food. And as for P, it is estimated that less than 20% of the mined phosphate rock aimed for fertilizers ends up as P in humans' food. Important for the low overall use of nutrients in world agriculture is the fact that so much of the biomass produced is used for feeding the livestock. Utilization of N in an animal's feed is normally in the range of 10–35% (with cattle in the lower and poultry in the higher range) meaning that the majority of feed N ends up in manure. This is also the case for P, with utilization rates between 15% and 40%, varying for livestock categories and feeding systems.

Nitrogen The yearly anthropogenical nitrogen input in the biosphere is estimated at approximately 140 Mton N of which B85 Mton is industrial fertilizer production, B33 Mton biologically fixed in leguminous crops, and B21 Mton produced in combustion processes and emitted as nitrogen oxides. This nitrogen input is in the form of reactive N as opposed to the major constituent of the atmosphere, inert N2. Consequently, each year, approximately 120 Mton reactive N enters agricultural production. The recently published book ‘The European Nitrogen Assessment’ provides the most comprehensive analysis of the nitrogen problem in agriculture and society. Ammonia (NH3) from livestock manure is a major pathway of losses of reactive N from agriculture. Globally, total nitrogen excreted in manure is estimated at approximately 112 Mton N (range 93–132 Mton) per year, thus amounting to the same magnitude as the input of new reactive N in agriculture. Ammonia losses provide approximately 20% of excreta-N in average, and there are great potentials for better use of manure in global agriculture, thus reducing emissions

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and lowering input of synthetic N-fertilizer, which are based on fossil fuels in production. Yearly losses of N in leaching and erosion from agricultural land are estimated at approximately 40 Mton N globally. The indicator ‘Nitrogen loading indicator’ is used for assessing watershed nutrient loads and shows that in Europe, water pollution from nitrogen is mainly the result of livestock production and fertilizer use. In India and southern parts of South America, livestock production is the dominant contributor whereas in North America and China, synthetic fertilizers dominate the total N load. However, when applying a life cycle-perspective on these findings, a considerable share of Nfertilizers is used in the cultivation of feed crops (e.g., 60% of European grains are used for feed) and leaching from the fertilizer use in these crops production is a result of demands in the livestock sector. Emissions of the GHG nitrous oxide (N2O) also represent a loss of reactive N from agriculture, but in absolute numbers, this is much lower than those of ammonia and nitrate. This is further discussed under in Section GHG Emissions and Global Warming.

Phosphorus Mined phosphate deposits are mainly used in food production; as fertilizers (80%) and mineral feed (5%), whereas the remainder goes to industrial uses, mostly detergents. With current use it is estimated that today's economically exploitable resource will be depleted within 125 years and total reserves (the ‘reserve base’) within 340 years. In the early 2000, global fertilizer use was roughly 15 Mton P per year in agriculture and approximately the same amount is produced in livestock manure annually of which approximately half is returned to agriculture and the rest is lost via land-fills, nonarable soils, and waters according to Cordell et al. (2009). Phosphorus in human excreta makes up approximately 3 Mton P per year and of this, only approximately 10% is returned to agriculture. It is obvious that livestock manure and human excreta must be better recycled to be used in agriculture to reduce the continuously growing use of fertilizer phosphorus. When cereals are used as feed, there are large P flows from the fertilized croplands to animal manure at livestock production units. Besides this P-flow, there are also substantial P fluxes in byproducts from cereals and pulses used in concentrates, via food and feed industry and finally ending up in manure. For example, after milling wheat, the majority of P in the grain ends up in the byproduct wheat bran whereas the flour for human consumption has a low P content. After extraction of soybeans and rapeseed, most of the crops' uptake of P is destined for the feed coproduct meal/cake and the vegetable oil produced only holds a small amount of P. Production of especially pork and poultry animals leads to large P flows from mined fertilizer phosphates to crop production (grain and soybeans), via feed and food industry to feed concentrates.

Eutrophication and Acidification Aquatic eutrophication means nutrient enrichment mainly from N and P of the aquatic environment. Excess input of

nutrients increases the primary production of fast-growing algae and plants adapted to low-nutrient conditions decreases. Also in the fish community there are shifts due to changes in the habitats. Under severe conditions, nutrient enrichment of coastal stratified waters (having sharp temperature gradients preventing mixing surface and bottom waters) can cause anaerobic or nonoxygen conditions and result in significant bottom fauna mortality and fish mortality. Terrestrial eutrophication is mostly an effect of excess input of N, as vegetation in natural ecosystems is mainly controlled by the limited availability of this nutrient. Atmospheric N deposition from human activities (most important NH3 from manure and NOx from traffic) leads to increased loads of N and, from this, follows changes in structures and functions in N-limited ecosystems. As explained earlier in the Section Nitrogen, NH3 volatilization from manure represents a significant N loss from agriculture and of total N excreted by the livestock, as much as 20–40% can be lost as NH3, depending on farming system, feeding routines, application methods, etc. Ammonia can also be an acidifying pollutant because it has a strong acidifying effect as a result of soil nitrification involving the conversion of ammonium into nitrate by microorganisms. Depending on the state of the ecosystem where the ammonia is deposited, the acidifying impact varies. Up to a certain level, a natural ecosystem can absorb deposited N, but above that level, excess nitrogen is leached and thus, the soil is ‘N-saturated.’ In forests saturated with N, nitrification and leaching of base cations and nitrate are usually the most important mechanisms behind soil acidification. There is a close interaction between terrestrial eutrophication and acidification.

GHG Emissions and Global Warming Unlike industrial and transport systems, carbon dioxide (CO2) from fossil fuel use is the least important GHG emitted from the animal sector. Instead, it is emissions of methane (CH4) and nitrous oxide (N2O) that contribute mostly to livestock products' GHG emissions. Also CO2 emissions due to land use and land use change (LULUC), most important from deforestation, are important sources of greenhouse gases, see Figure 2. The global warming potential (GWP) for different greenhouse gases is normally calculated for a 100-year time horizon in kilogram carbon dioxide equivalents (kg CO2e): CO2 1, CH4 25, and N2O 298. FAO has estimated that global livestock production make up approximately 15% of total GHG emissions when land use-related CO2 emissions also are included.

Methane As seen in Figure 2, enteric fermentation is the most important source of CH4 emissions from livestock production. CH4 is also emitted from slurry storages and in a warm climate, this source can be substantial. Methane is approximately 25 times more effective in trapping heat in the Earth's atmosphere than CO2 and its atmospheric concentration has increased from approximately 715 ppb preindustrial to 1774 ppb in 2005, i.e., by close to 150%. According to ‘Livestock's Long Shadow,’

Environmental Impact of Meat Production | Primary Production/Meat and the Environment

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3 N2O

CH4

CO2

Billion ton CO2 equivalents

2.5 2 1.5 1 0.5

s op d fe e s

fe e ou

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M

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Figure 2 Emissions of greenhouse gases (CO2, CH4, and N2O) from the global livestock sector. Reproduced from FAO, 2006a. Livestock's long shadow − Environmental issues and options. Available at: www.fao.org/docrep/010/a0701e/a0701e00.HTM (accessed 20.01.14).

global emissions from enteric fermentation and manure management in 2004 were 85.63 and 17.52 Mton CH4, respectively. This corresponds to approximately 2.58 billion ton CO2 representing approximately 5.3% of total global GHG emissions in 2004.

Nitrous Oxide Emissions of the GHG nitrous oxide (N2O) also represent a loss of reactive N in agriculture, but in absolute numbers, much lower than the losses of reactive N as ammonia and nitrate. Globally, it is estimated that approximately 2.8 Mton N yr−1 (1.7–4.8) is lost as N2O–N from agriculture, mainly due to denitrification and nitrification processes in the soil and also nitrogen transformations in manure. Manure storage, manure spreading in fields, and ammonia emissions from manure give rise to substantial N2O emissions from the global livestock sector (Figure 2). Nitrous oxide is a strong GHG that is present in very low concentrations in the atmosphere. It is approximately 300 times more effective than CO2 in trapping heat and has a very long atmospheric life-time (4100 years). Preindustrial concentration was approximately 270 ppb N2O, which has grown to 319 ppb in 2005, i.e., an 18% increase. N2O emissions have become more important in the second half of the twentieth century as a result of the strong increase in synthetic N fertilizer use in agriculture.

Carbon Dioxide As seen in Figure 2, emission of fossil CO2 is of minor importance for the global livestock sector's GHG emissions. But this is not the case for a highly industrialized region, such as

the EU27, where the Joint Research Center of the EU Commission estimates that approximately 20% of the European livestock sector's GHG emissions come from the use of fossil fuels in animal production. CO2 emissions from land-use change processes are closely connected to expanding agricultural production and land clearance. Carbon emissions from forest clearing constituted approximately one-third of total anthropogenical CO2 emissions in the period 1850–2005. In the past 50 years, there has been a stabilizing (or even decrease in agricultural land) in many regions but in the tropics, deforestation is still occurring rapidly. During the 1990s, it is estimated that tropical deforestation gave rise to CO2 emissions in the order of 3.7– 8 Gton CO2 per year, comprising 14–25% of total anthropogenical emissions. Today, land use change, mostly deforestation, accounts for approximately 10% of global CO2 emissions, and the emission trend has been falling over the past 10 years compared to levels during the 1990s. There are large uncertainties in estimates of GHG emissions from deforestation.

Indicators of a Changing Climate The Intergovernmental Panel on Climate Change (IPCC) reports about a changing climate: The average global temperature has increased by 0.74 °C during the past 100 years (1906–2005) and during that period, average Arctic temperature has increased almost twice the global average. This global warming has led to a number of observed changes, for example, mountain glaciers and snow cover have declined on average in both hemispheres, global average sea level has risen at an average rate of 1.8 mm per year from 1961 to 2003, longterm trends from 1900 to 2005 have been observed in precipitation amount over many large regions, more intense and

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longer droughts have been observed over wider areas since the 1970s, particularly in the tropics and subtropics, and widespread changes in extreme temperatures have been observed over the past 50 years. Cold days, cold nights, and frost have become less frequent, whereas hot days, hot nights, and heat waves have become more frequent.

Chemicals Pesticides are chemical substances used to kill or control any pests, mainly weeds, insects, and fungus-attacking crops. There are large economic incentives to use pesticides to reduce the occurrence of pests and hence increase the quality and quantity of crop yield. In addition, use of pesticides is less laborintense than traditional agricultural management practices. The disadvantages are pesticides potentially have toxic effects on humans and ecosystems and there are increasing risks of resistant pests. The impact of pesticides on different organisms varies greatly depending on their toxicity (direct and indirect), persistence, and fate. The use of pesticides and associated changes in management practices may also lead to biodiversity decline. Extensive use of and reliance on one or only a few pesticides may also result in increased resistance to the pesticide(s) due to natural selection in the targeted weed-, fungi-, insect populations. An immediate example that is related to livestock production is a growing number of weed species that have evolved resistance to the important herbicide glyphosate, mainly occurring in areas where farmers grow feed crops (most importantly soybeans, but also maize) that have been genetically engineered to tolerate glyphosate. Owing to adaptation and natural selection in weed populations, the increased and often exclusive reliance on glyphosate to manage weeds in genetically engineered crop systems have led to that resistance to glyphosate having evolved in some weed species. Veterinary medicines are another important chemical group used in livestock production and antibiotics are, by far, the most commonly used veterinary medicines and of great significance to modern livestock production, not only to treat diseases but also to promote growth and improve feed efficiency. Not all antibiotics are absorbed by the animal; sometimes 30–90% are excreted in manure. After excretion, the metabolites may still be bioactive and transformed back to the parent substance. The effect of pharmaceuticals on the environment has emerged as a scientific field over the past years. Also for medicines, resistance is a growing problem. The main concern regarding the widespread use of antibiotics in veterinary medicine is the development of resistant bacterial strains, a health risk to both humans and livestock animals. Of special concern is antibiotic therapy in food-producing animals. Direct contact with animals, and thereby the risk of bacteria spreading via the food chain, enables the selection of bacterial strains resistant to antibiotics used in human therapy.

Conclusion Livestock production is a key driver of environmental change. Already at present, the global livestock sector is one of the top

two or three most significant contributors to some of the most important environmental problems, at every level, from local to global. The FAO prognosis of doubling global animal production to 2050 means the task of cutting the environmental impact per unit of livestock production by 50% to maintain the level of damage at the present level. This presents an enormous challenge to stakeholders in the livestock sector to reduce the sector's environmental impact. It involves improving efficiency in crop and animal production, reducing enteric CH4 emission, improving manure management and handling, solutions discussed by de Boer et al. (2011). In recent years, there have been increasing discussions about the total intake of animal products in high-income countries and the possible need in future for reducing intake of animal products so that food-related emissions will meet future climate targets, this issue is further discussed in papers by Wirsenius et al. (2011), Garnett (2011), and Cederberg et al. (2012).

See also: Curing: Natural and Organic Cured Meat Products in the United States. Meat, Animal, Poultry and Fish Production and Management: Meat Production in Organic Farming; Red Meat Animals. Modeling in Meat Science: Meat Quality

Further Reading Beusen, A.H.W., et al., 2008. Bottom-up uncertainty estimates of global ammonia emissions from global agricultural production systems. Atmospheric Environment 42 (24), 6067–6077. Bouwman, A.F., Beusen, A.H.W., Billen, G., 2009. Human alteration of the global nitrogen and phosphorus soil balances for period 1970−2050. Global Biogeochemical Cycles 23, GB0A04, doi:10.1029/2009GB003576. Cederberg, C., 2010. Improving nutrient management in agriculture to reduce eutrophication, acidification and climate change. In: Sonesson, U., Berlin, J., Ziegler, F. (Eds.), Environmental Assessment and Management in Food Industry: Life Cycle Assessment and Related Approaches. Oxford, UK: Woodhead Publishing Limited, pp. 3–15. Woodhead Food Series No. 194. Cederberg, C., Hedenus, F., Wirsenius, S., Sonesson, U., 2012. Trends in greenhouse gas emissions from consumption and production of animal products in Sweden − Implications for a long-term climate target. Animal, doi:10.1017/ S1751731112001498. Cordell, D., Drangert, J.-O., White, S., 2009. The story of phosphorus: Global food security and food for thought. Global Environmental Change 19 (2), 292–305. de Boer, I.J.M., Cederberg, C., Eady, S., et al., 2011. Greenhouse gas mitigation in animal production: Towards an integrated life cycle sustainability assessment. Current Opinion in Environmental Sustainability 3, 423–431. Denman, K.L., et al., 2007. Couplings between changes in the climate system and biogeochemistry. In: Solomon, S.D., Qin, M., Manning, Z. (Eds.), Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, UK and New York, NY, USA: Cambridge University Press, pp. 539–546. Erisman, J.W., Sutton, M.A., Galloway, J., Klimont, Z., Winiwarter, W., 2008. How a century of ammonia synthesis changed the world. Nature Geoscience 1 (10), 636–639. European Commission, Joint Research Center (JRC), 2010. Evaluation of the livestock sector's contribution to the EU greenhouse gas emissions (GGELS) − Final report. Available at: http://ec.europa.eu/agriculture/analysis/external/ livestock-gas/full_text_en.pdf (accessed 20.01.14). FAO, 2006a. Livestock's long shadow − Environmental issues and options. Available at: www.fao.org/docrep/010/a0701e/a0701e00.HTM (accessed 20.01.14). FAO, 2006b. World agriculture: Towards 2030/2050, Interim Report. Available at: www.fao.org/docrep/009/a0607e/a0607e00.htm (accessed 20.01.14).

Environmental Impact of Meat Production | Primary Production/Meat and the Environment FAO, 2009. The state of food and agriculture − Livestock in the balance. Available at: www.fao.org/docrep/012/i0680e/i0680e.pdf (accessed 20.01.14). Foley, J., et al., 2011. Solutions for a cultivated planet. Nature 478, 337–342. Garnett, T., 2011. What are the best opportunities for reducing greenhouse gas emissions in the global food system? Food Policy 36, S23–S32. Klink, C.A., Machado, R.B., 2005. Conservation of the Brazilian Cerrado Conservación del Cerrado Brasileño. Conservation Biology 19 (3), 707–713. Sarmah, A.K., Meyer, M.T., Boxall, A.B.A., 2006. A global perspective on the use, sales, exposure pathways, occurrence, fate and effects of veterinary antibiotics (VAs) in the environment. Chemosphere 65 (5), 725–759. Smit, A.L., Binraban, P.S., Schröder, J.J., Conijn, J.G., van der Meer, H.G., 2009. Phosphorus in Agriculture: Global Resources, Trends and Developments. Wageningen, The Netherlands: Plant Research International B.V. Waltz, E., 2010. Glyphosate resistance threatens Roundup hegemony. Nature Biotechnology 28 (10), 1129. Wirsenius, S., Hedenus, F., Mohlin, K., 2011. Greenhouse gas taxes on animal food products: Rationale, tax scheme and climate mitigation effects. Climatic Change 108 (1−2), 159–184.

Relevant Websites www.nine-esf.org/ENA-Book The European Nitrogen Assessment. www.globalcarbonproject.org The Global Carbon Project (GCP). www.ipcc.ch/publications_and_data/ar4/wg1/en/ch2.html The Intergovernmental Panel on Climate Change (IPCC). www.millenniumassessment.org/documents/document.354.aspx.pdf The Millennium Assessment.

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EQUIPMENT CLEANING

KJ Allen and S Wang, University of British Columbia, Vancouver, BC, Canada r 2014 Elsevier Ltd. All rights reserved.

Glossary Chemical energy Energy derived from cleaning agents used to disrupt the chemical interactions in a soil–surface interface. Cleaning agent A chemical used to disrupt and solubilize soils. Contact time Time allotted for cleaning agent to interact with a soil. Food contact surface Equipment surface that physically contacts food during production. Mechanical energy Physical (i.e., kinetic) methods (e.g., scrubbing, pressure sprays, turbulent flow) used

to create energy for the disruption of soil–surface interactions. Planktonic cells Bacterial cells that are suspended in a medium (i.e., not attached to a surface). Sanitizer Chemical agent used to inactivate microorganisms. Soil Any substance present in a food production environment that should not be present. Surface energy The energy associated with a soil–surface interaction that must be overcome for effective soil removal. Thermal energy Heat energy used to facilitate disruption of soil–surface interactions.

Introduction The maintenance of a hygienic plant environment is a fundamental requirement for the consistent production of food that is safe, wholesome, and stable during the specified shelf-life. An inability to reliably and effectively clean and subsequently sanitize food production equipment may lead to increased risks of product spoilage and/or contamination by allergens and/or pathogenic microorganisms. Accordingly, appropriate efforts should be made to minimize the presence of soils before, during, and after production of food. Soil removal is essential before the application of sanitizing chemicals. It is well established that cleaning and sanitizing contribute equally to reductions in numbers of microorganisms on equipment surfaces. For this reason, appropriate cleaning agents and strategies can be selected only with knowledge of the types of soil expected from individual raw materials and from processed food products. Inadequate cleaning may lead to soil accumulation. Biofilms may then form on equipment surfaces, and cause corrosion, reductions in processing efficiency, and problems with finished product quality. When deciding on procedures for control of soils, the benefits from cleaning and sanitation must be weighed against the related costs. Although increases in the number or duration of breaks in production for cleaning and sanitation will enhance soil control (Figure 1), they also result in higher costs for cleaning/sanitation chemicals, water, sewage, energy, and labor (Table 1). Accordingly, to balance cleaning-related costs against production efficiency and control of microbiological contamination, environmental trend analysis of microbiological data may be used to fine-tune production–sanitation cycles.

508

Soil mass

A

1

2

3

4 Number of B periodic cleans

Time Figure 1 Accumulation of soils over time as impacted by two cleaning approaches: (A) no periodic cleaning and (B) with periodic cleaning. Adapted with permission from Holah, J.T., 2003. Cleaning and disinfection. In: Lelieveld, H.L.M., Mostert, M.A., Holah, J., White, B. (Eds.), Hygiene in Food Processing. Cambridge: Woodhouse Publishing Limited (Chapter 13). Table 1

Costs associated with cleaning and sanitation

Input

% Contribution to total cost

Labor Water and sewage Energy and utilities Cleaning agents and sanitizers Corrosion damage Other

46.5 19.0 8.0 6.0 1.5 19.0

Source: Adapted with permission from Marriot, N.G., 1997. Essentials of Food Sanitation. New York: International Thompson Publishing and Chapman and Hall (Chapter 7).

Encyclopedia of Meat Sciences, Volume 1

doi:10.1016/B978-0-12-384731-7.00212-9

Equipment Cleaning

Soils, Surfaces, and Cleaning The original definition of a soil was any material or substance that is, but should not be, present on a solid substrate (i.e., surface) of interest. Although this definition recognizes that a soil may be any sort of material (e.g., dirt, dust, grease, food derivatives, etc.), it does not take account of the complex natures of many soils. Subsequent definitions categorize soils on the basis of their solubility in acid, alkali, or water. These definitions are highly relevant to the selection of cleaners that will appropriately interact with and thus solubilize a soil. More recent classifications of soils recognize their essential chemical properties. Thus, soils are characterized as mineral (lime, milk stone, etc.), organic, or microbiological, or composite when a soil is composed of two or more of the simpler soils; but not all soils conform to this classification. Nonconforming soils include dust and debris. Organic soils are further categorized as carbohydrate (CHO), lipid, or protein based, and these subcategories may be further characterized. For example, CHOs may be identified as being water soluble or producing Maillard reaction products following heating. Such information is important as water-insoluble soils and Maillard reaction products are more difficult to remove than water-soluble CHOs. For proteins, it is essential to know the denaturation temperature and the appropriate pH to use for cleaning. Processing or cleaning waters at temperatures above the denaturation temperature or cleaning solutions of inappropriate pH may cause partial or total denaturation of soluble proteins, which consequently become insoluble and difficult to remove from surfaces. In addition, the fluidity and solubility of soil lipids should be considered, that is, whether the lipids are water soluble or insoluble, and whether they are liquid or solid at room temperature. Knowledge of these matters allows realistic considerations of the complex nature of soils, and facilitates appropriate cleaner selection. Another key factor that affects soil deposition on equipment surfaces is the nature of the surface. It is well established that surfaces that are corroded, have obvious defects, or are

Table 2

509

porous are more difficult to clean than smooth surfaces, and may have microbial harborage sites in which biofilms can develop. The difficulty with removing soils from such surfaces is a result of the much greater area available for contact with soils than is available on smooth surfaces. Further, while suspension of a soil in water requires the input of energy, soil adherence to surfaces is an energetically favorable process. The more interaction there is between a soil and a surface, the more energy is required to disrupt the interactive forces in order to displace and remove the soil. Cracking and pitting of smooth, impermeable surfaces increases areas for adherence of soil, and therefore equipment with such defects should be avoided. Interactions between soil and surface are determined by the chemical composition of the surface as well as its roughness. Thus, to maximize cleanability, all surfaces in food production environments should be smooth and made of hygienically acceptable materials (Table 2). Therefore, equipment should be constructed from hygienic grade plastics, rubbers, stainless steel, etc., whereas porous materials, such as wood, should be strictly avoided. The chemical reactivity of the surface has a critical effect on the deposition of soils on both food contact surfaces (FCS) and nonfood contact surfaces (nFCS). Various grades of stainless steel are available in which the contents of chromium, nickel, and other metals alloyed with iron are adjusted to improve corrosion resistance under different conditions of use. These formulations balance cleanability, durability, and resilience to oxidizing compounds routinely used in sanitation programs. Importantly, sanitation crews should report any corrosion, pitting, or damage to equipment to allow the matter to be corrected before product safety or quality is compromised.

Surface Energy To effectively remove a soil, the surface energy (SE), i.e., the interaction between the soil and the surface, must be overcome. Energy used to overcome the SE may be chemical,

Characteristics of hygienically acceptable and unacceptable surfaces observed in food production environments and equipment

Material

Characteristics

Precautions/suggestions

Wood Black metals

Draws moisture and lipids into porous structure; alkalis degrade it Acids and chlorinated compounds will corrode them

Tin

May be corroded by strong acid or alkali cleaners

Concrete

Etched by acidic foods and cleaning compounds

Glass

Should be smooth and impervious, but may be etched by strong alkaline cleaners May be etched by strong alkaline cleaners

Its use should be avoided due to hygienic and structural concerns Tinning or galvanizing minimizes corrosion. Neutral detergents should be used for cleaning Tin surfaces should be used only for surfaces that do not contact food Acid-resistant, dense concrete should be used in production environments; alternative, use acid brick Mild cleaners should be used for cleaning

Paint Rubber

Stainless steel

Firm, nonporous rubber should be used. Organic solvents and strong acids may degrade it, though it is resistant to alkaline detergents Smooth, impervious, resistant to corrosion, may oxidize at elevated temperature, nonmagnetic, easy to clean

Nontoxic paints may be used in production environments if issues with peeling are unavoidable Rubber cutting boards warp and dull knives

Expensive. Halogen compounds may corrode stainless steel

Source: Adapted with permission from Marriot, N.G., 1997. Essentials of Food Sanitation. New York: International Thompson Publishing and Chapman and Hall (Chapter 7).

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mechanical (i.e., kinetic), or thermal, or a combination of these. Cleaning chemicals provide chemical energy to break apart and disperse soils, and keep removed soils suspended in solution so that rinsing is effective for carrying away the dislodged soil. Mechanical energy may be generated by scrubbing, pressure sprays, or turbulent flow in pipes, vessels, etc. that are cleaned using a clean-in-place (CIP) system. One of the most effective yet commonly overlooked means of overcoming SE is scrubbing. Thermal energy enhances most chemical and physical methods of reducing soil–surface interactions. For example, heated cleaning water increases the efficacy of chemical cleaners approximately twofold for every increase of 10 °C. This is particularly useful for lipid-based meat soils, as application of heated cleaning solutions that exceed the melting temperature of the fat greatly enhances its removal. However, if soils include proteinacious components, care must be taken not to exceed 55 °C because above this temperature protein denaturation may occur with the formation of insoluble residues that are difficult to remove. Moreover, at temperatures 450 °C, sublimation of iodine-based sanitizers may occur, reducing the antimicrobial activity of the sanitizer. In addition, time is a key factor for the effectiveness of a cleaning program. In general, the longer cleaning-related chemicals remain in contact with soils, the more successful the soil removal process will be. Conversely, if the contact time between soil and cleaning compounds is not sufficient, stubborn soils may persist on equipment surfaces. Costs linked to chemical, mechanical, and thermal energy inputs may be reduced by prolonging the contact time between cleaning agent and the soiled surface; and combining chemical, mechanical, and/or thermal energy inputs in a cleaning regime will reduce the respective energy input required from each energy source. That is, less detergent will be required if the cleaning water is heated and the surface is scrubbed. However, if cleaning efficacy is enhanced by increased scrubbing or the use of higher concentrations of detergent, the cost of labor, or cleaning agent will increase. Suggested combinations of energy input are

detailed in Figure 2. Overall, smaller items such as utensils, pails, and molds require a high input of mechanical energy, with soil removal being improved with soaking in a solution of chemical cleaner before scrubbing. Disassembled equipment that can be transported to soaking tanks should be treated in a similar manner. In contrast, for larger equipment, manual and thermal energy inputs are often necessarily limited, resulting in increased reliance on chemical and thermal energy. However, reduced concentrations of chemical cleaners and lower water temperature may then have to be used to minimize risks to workers engaged in cleaning. In such circumstances, increased cleaning agent contact time may be used to aid in soil removal. The quality of water used for cleaning is also important. Hard water with high concentrations of calcium and magnesium salts, sulfates, and bicarbonates reduces the activities of some cleaning and sanitizing agents. Therefore, it is advisable to soften cleaning water with chelating agents or sequesterants. In addition, softening of cleaning water will minimize the deposition of stubborn mineral deposits on equipment surfaces. Obviously, potable water must be used for cleaning all food production equipment and facilities.

Composition of Soils The composition of soils deposited during the production of food will reflect the raw materials used, the end product, and the processing technology or technologies employed. In addition, microorganisms present in or on raw materials or in the production environment may contaminate surfaces of equipment and, ultimately, the food being produced. In the production of raw and processed meat products, predominant soils consist of lipid and proteinacious components. These soils often accumulate to high levels during long production runs, thereby limiting the effectiveness of CIP cleaning and

Energy input

Heavy soil

Light soil

CHEM

CHEM

CHEM

CHEM

MECH

MECH MECH

TEMP

MECH

TEMP

Manual small items

CHEM

CHEM

MECH

TIME

CHEM

TIME Manual tray wash

TEMP

TEMP

TIME

TIME

Manual large areas

Mist

MECH

TEMP

TEMP

TIME

TIME

Foam

Gel

MECH

TEMP TIME Mechanical scrubbing

Cleaning technique Figure 2 Suggested combinations of energy input for the removal of light and heavy soils. Adapted with permission from Holah, J.T., 2003. Cleaning and disinfection. In: Lelieveld, H.L.M., Mostert, M.A., Holah, J., White, B. (Eds.), Hygiene in Food Processing. Cambridge: Woodhouse Publishing Limited (Chapter 13).

Equipment Cleaning

Table 3

511

Soil solubility characteristics and suggested cleaning agent properties

Nature of soil

Solubility characteristics

Recommend cleaning agent

Carbohydrates, organic acids, salts Proteinacious (e.g., fish, meat, poultry) Starch-rich (e.g., fruits, tomatoes) Lipid-rich (e.g., adipose, butter, oils, etc.) Inorganic soils (e.g., hard water deposits, milk stone)

Water soluble Alkali soluble, slightly acid soluble, water soluble Alkali soluble, partially water soluble Alkali soluble, water insoluble Acid soluble, alkaline insoluble, water insoluble

Mild alkaline detergent Chlorinated alkaline detergent Mild alkaline detergent Mild-to-strongly alkaline detergents Acid cleaners

Source: Adapted with permisson from Elliot (1980).

sanitation strategies. Solubility characteristics of soils and the type of cleaning agents recommended for use with each type of soil are shown in Table 3.

Soil Removal Strategies for effective cleaning are specific to each food production facility. However, a general step-wise strategy for effective soil removal in most production and processing facilities is as follows: (1) gross soil should be physically removed before moving any equipment, and then utensils and movable equipment should be disassembled and moved to a location suitable for cleaning activities; (2) gross soils along the production line and throughout the production environment should be removed, with larger soils being picked up to prevent the unnecessary spreading of soils; (3) because lipidand protein-rich soils can be expected in meat production facilities, equipment should be subjected to an initial rinsing with hot water at temperatures o55 °C; (4) remaining soil should be disrupted using chemical, mechanical, and thermal energy, while adhering to the concentrations and contact times recommended for each cleaning agent; and (5) equipment should be rinsed with preferably pressurized hot water at o55 °C to facilitate dispersion of soils from equipment surfaces being cleaned. Following soil removal and sanitation, potable water should be used to remove cleaning and sanitizing agent residues from equipment surfaces. Although levels of microorganisms should be greatly reduced by cleaning, microorganisms may still be present on surfaces and/or in hard-to-clean areas. As such, after rinsing it is important to remove excess water from FCS and nFCS throughout the production environment. Moisture facilitates the survival and proliferation of microorganisms. Therefore, after cleaning, equipment and the processing facility should be dried as much as is practicable. It should be noted that the cleaning process itself may serve to disperse soils in undesirable ways. If cleaning agents are not effective in keeping soils suspended, re-deposition of soils on equipment may occur, at their original sites or elsewhere. In addition, the use of pressure sprayers to remove large accumulations of soil will lead to increased soil deposition throughout the production environment. Both highpressure/low-volume and low-pressure/high-volume sprayers generate aerosols, which have been shown to redistribute bacteria and soils within a production area. Accordingly, it may be necessary to limit the use of pressure sprayers in areas where risks of microbiological contamination of product are high.

Hygienic Design of Equipment and Facility The persistence of bacterial pathogens in food processing environments poses major risks of processing and/or postprocessing contamination of product. Equipment that is not hygienically designed or is improperly installed or maintained will compromise the efficacy of a cleaning and sanitation program by introducing harborage sites in which pathogens will be protected from sanitizing treatments. For example, if meat slicers are not designed to permit easy and quick disassembly, routine cleaning may not be carried out effectively. Accordingly, slicers have been identified as the sources of product contamination in several listeriosis outbreaks linked to ready-to-eat meats. Similarly, equipment used in facilities for breaking beef carcasses have been shown to present major sanitation challenges. Therefore, hygienic design of the food processing equipment and premises is a critical prerequisite for effective cleaning and sanitation. Standards for sanitary fabrication, construction, and design of food processing equipment have been developed by a variety of standards organizations, such as 3-A Sanitary Standards, Inc., the National Sanitation Foundation, and the European Hygienic Energy & Design Group. Although there are some differences among these standards, the objective of all is the application of sound sanitary principles in the design and manufacture of food processing equipment. The general requirements for hygienic meat processing equipment are: 1. Equipment should be made of compatible materials. Materials used for construction of food processing equipment shall be completely compatible with the product, the processing environment, and cleaning and sanitizing procedures. To ensure durability, materials should be corrosion and abrasion resistant and, where applicable, capable of being shaped. 2. Self-draining. All pipelines and equipment should be selfdraining. Residual liquids in or on equipment harbor and promote microbial growth or, in the case of cleaning fluids, result in chemical contamination of product or corrosion of equipment surfaces (Figure 3). 3. No dead spaces and niches. Hollow areas should be hermetically sealed and introduction of dead spaces during installation should be avoided. Equipment parts should be free of pits, cracks, corrosion, and other visible defects (Figure 4). 4. Accessible for inspection, maintenance, cleaning, and sanitation. Equipment should be designed so that all product contact surfaces can attain the required sanitized or sterilized condition. Equipment with obvious defects should be replaced.

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5. No microbial ingress. Where appropriate (e.g., aseptic processes), equipment should be designed to prevent microorganisms migrating from the external environment onto product contact surfaces, either directly or via soils. 6. Hygienic design of maintenance enclosures. Maintenance enclosures and human–machine interfaces, such as push buttons, valve handles, and panels, should be designed so that they prevent the entry and/or accumulation of soils. Enclosure surfaces should be sloped to an outside edge to avoid them being used for storage (Figure 5). 7. Validated cleaning and sanitizing protocols. Procedures for cleaning and sanitation should be clearly described and proven effective. Care should be taken to ensure that chemicals recommended for cleaning and sanitation are compatible with the equipment and manufacturing environment.

Non-drainable designs

In general, if care is not taken to ensure the hygienic design of the processing facility and equipment, effective cleaning will be severely compromised because of microbial harborage sites and biofilm development.

Cleaning Compounds The primary function required of a cleaning compound is to disrupt soil–surface physicochemical interaction. Major considerations in cleaning compound selection are: (1) the physicochemical characteristics of the soil to be cleaned; (2) the chemical characteristics of the cleaning agent(s); (3) the application method; and (4) the surface area and

Drainable designs

Residue

Rounded

Sloped ≥3°

Figure 3 Examples of acceptable vs. unacceptable self-drainage design for tanks and vessels. Adapted from EHEDG, 1995. Hygienic design of equipment for open processing. Trends in Food Science and Technology 6 (9), 305–310.

Unacceptable design

Figure 5 Hygienic design is a necessity for easy-to-clean production systems in hygiene-critical processes in the food industry. Reproduced with permission from Schmitt, H., Koch, H.R., 2011. Hygienic Design of Enclosure Boxes in Relation to High Pressure Cleaning?

Acceptable design

Domed nut

Crevice

Optimal design Seal (controlled compression)

Seal (controlled compression)

Product

Seal of nut Metal-to-metal contact (a)

(b)

(c)

Figure 4 Design of dismountable joints: (a) crevices between sheet rims may lead to hygenic risks; (b) if exposure of screws to product is unavoidable, domed nuts, metal-backed seals and sealed rims on the overlapped sheets should be used; (c) optimal design uses sealed sheet rims and screw nuts on the reverse side to avoid direct contact with the product. Adapted from EHEDG, 1995. Hygienic design of equipment for open processing. Trends in Food Science and Technology 6 (9), 305–310.

Equipment Cleaning

design of the equipment to be cleaned. Generally, meat soils comprise lipids and proteins. To effectively remove these, alkaline cleaners with a pH of 11 or higher are commonly used. Specific types of cleaning compounds used for meat soil removal are: 1. Strong alkaline cleaners. These are used to saponify fats and remove heavy meat soils on metal surfaces, such as those found in smokehouses, boiling tanks, soak tanks, rail trolleys, and hooks. These agents pose serious risks of chemical injury to workers and may corrode surfaces and darken aluminum equipment. Components of strong alkaline cleaners include caustic soda and silicates having high N2O:SiO2 ratios. The addition of silicates to caustic soda, however, reduces corrosiveness and improves soil penetration and rinsing properties. 2. Heavy-duty alkaline cleaners. The active ingredients of these cleaners may be sodium metasilicate, sodium hexametaphosphate, sodium pyrophosphate, or trisodium phosphate. Although these generally do not corrode aluminum, the addition of sulfites may be necessary to reduce corrosion of tin alloys. These agents are frequently used for CIP, and for cleaning high-pressure rinsing equipment and mechanized equipment found in meat and poultry plants. They can, however, corrode metal parts and may cause eye damage and irritation of the skin and respiratory tract. 3. Mild alkaline cleaners. Mild alkaline cleaners commonly contain sodium bicarbonate. Liquid mild cleaners are frequently used for hand cleaning lightly soiled areas in meat processing plants, and are compatible with most surfaces. In the meat industry, they are used as general-purpose cleaners for hide washing equipment, floors, walls, and equipments made of rubber or plastic. Although increased chemical energy may be applied by increasing cleaning agent concentrations, concentrations exceeding manufacturer recommendations may result in denaturation of proteins, thereby reducing cleaning effectiveness.

Biofilms Biofilms form on surfaces. They are complex communities of microorganisms that are embedded in a matrix of polysaccharide materials secreted by the microbes themselves. Biofilms can form on any surface that is exposed to nonsterile water or other liquids, including but not limited to walls, floors, drains, process lines, pipes, and surfaces on/in refrigeration and air handling units. When bacteria colonize a surface, the cells secrete extracellular polysaccharide, proliferate, and eventually form a mature biofilm. Biofilms may not be effectively removed by cleaning agents because the bacteria within them are more resistant to heat and sanitizers than their planktonic forms. Biofilms may also enhance the corrosion of stainless steel, and bacteria from biofilms are continuously sloughed off into the foods and/or food processing environment. Biofilm formation is of particular concern with equipment that is difficult to clean, such as slicers and equipment requiring disassembly for cleaning. With such equipment, cleaning agents may not be effectively delivered to all parts of the equipment, leading to ineffective soil removal. Persistent soils will provide substrates

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for microbial growth and biofilm development, potentially leading to quality and/or safety issues. For example, two US listeriosis outbreaks 12 years apart were linked to a single turkey meat producer. The causative strains in both outbreaks were shown to be identical by molecular typing, and had been recovered from the food production facility in between the outbreaks. Biofilm formation throughout a food production facility should be closely controlled by preventing the establishment of harborage sites. Biofilms may also impact operating efficiency. Accumulation of biofilms on processing equipment may reduce processingrelated heat transfer, promote corrosion, or foul filters. At this time, there are no specific procedures for the removal and disinfection of biofilms from equipment surfaces. As bacteria within biofilms may be up to 1000 times more resistant to biocides than planktonic organisms, biofilm removal cannot be achieved by increasing sanitizer concentration alone. Rather, combinations of chemical and mechanical energy must be used to improve the delivery and efficacy of cleaning and sanitizing agents. The use of cleaners and sanitizers in combination may enhance removal of biofilms. A suitable combination of cleaner and sanitizer can dissolve the biofilm and the organic material to which it adheres, allowing the sanitizer to inactivate the released cells. Current information also suggests that the application of heat with chemical sanitizers can be more effective against biofilms than chemical sanitizers alone. However, the application of heat may lengthen sanitation time, incur higher energy costs, negatively impact parts of equipment such as seals and gaskets, and increase risks to workers. Difficulties associated with biofilms may be increased by the increasing duration of production runs. To optimize production efficiency, production runs in the food industry generally are becoming longer, with minimal down-time for sanitation. Although the use of hygienic equipment, inspection/maintenance, and the appropriate use of cleaning and sanitation chemicals may efficiently control microbiological contamination when run times are not extended, longer production runs inevitably lead to increased soil deposition and longer periods before any biofilms are disturbed. This may contribute to increased opportunity for biofilm formation and issues with maintenance of a hygienic production environment. Novel measures for control of biofilms are being sought. These include the use of enzyme-based detergents that may degrade biofilms, bacteriophages that can infect biofilm cells, and bacterial metabolites that affect the activities of cells in biofilms. These methods would be highly specific, nontoxic, and usable in-process, and thus could be feasible approaches for controlling microorganisms commonly found in food plant biofilms. However, they have as yet not been successfully applied in the food industry.

Assessing the Effectiveness of a Cleaning Program Evaluation of the efficacy of cleaning should be carried out before sanitation. The methods available for rapid assessment of cleaning efficacy include: visual inspection of the equipment and environment; adenosine triphosphate (ATP) bioluminescence monitoring to detect the presence of ATP from

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eukaryotic (i.e., meat tissues) and prokaryotic cells; and protein indicator strips to detect protein-based soils remaining on equipment. Failure to meet the standard specified for a test of cleaning should result in repetition of the equipment cleaning protocol.

Summary Effective cleaning of equipment used in the processing and production of meat and meat-based products is an ongoing challenge. Raw materials and processed meat products contaminate equipment surfaces with soils rich in fats and proteins, which are difficult to remove. A thorough understanding of expected soil chemical properties is required to select appropriate cleaning agents, most of which are alkaline based. Combinations of chemical, thermal, and mechanical energy inputs should be used to maximize the removal of stubborn soils while minimizing costs of energy, labor, and cleaning agents. If food production equipment is not hygienically designed and properly maintained, or is made of inappropriate materials, the cleanability of equipment surfaces is diminished. Under such circumstances, microbial harborage sites develop in which organic substrate and resident microorganisms accumulate, resulting in biofilm development. The goal of a cleaning program should be to minimize opportunities for biofilms to form. If equipment cleaning is effectively executed, issues with premature spoilage, allergens, and/ or pathogens in end products will be minimized.

See also: Biofilm Formation. Chemical Analysis for Specific Components: Major Meat Components. Cooking of Meat: Physics and Chemistry. Potential Chemical Hazards Associated with Meat. Processing Equipment: Battering and Breading Equipment; Brine Injectors; Mixing and Cutting Equipment; Smoking and Cooking Equipment; Tumblers and Massagers. Residues in Meat and Meat Products: Residues Associated with Meat Production

Further Reading Carpentier, B., Cerf, O., 2011. Review − Persistence of Listeria monocytogenes in food industry equipment and premises. International Journal of Food Microbiology 145, 1–8. Detry, J.G., Sindic, M., Deroanne, C., 2010. Hygiene and cleanability: A focus on surfaces. Critical Reviews in Food Science and Nutrition 50, 583–604. Gram, L., Bagge-Ravn, D., Ng, Y.Y., Gymoese, P., Vogel, B.F., 2007. Influence of food soiling matrix on cleaning and disinfection efficiency on surface attached Listeria monocytogenes. Food Control 18, 1165–1171. Jackson, L.S., Al-Taher, F.M., Moorman, M., et al., 2008. Cleaning and other control and validation strategies to prevent allergen cross-contact in foodprocessing operations. Journal of Food Protection 71, 445–458. Lelieveld, H.L.M., Holah, J., White, B., Mostert, M.A. (Eds.), 2003. Hygiene in Food Processing: Principles and Practice. Boca Raton, FL: CRC Press. Marriott, N.G., Gravani, R.B., 2006. Principles of Food Sanitation. New York, NY: Springer. NSF International, 2009. Hygiene Requirements for the Design of Meat and Poultry Processing Equipment (Tracking Number 14159-1i8r1). Available at: http:// standards.nsf.org/apps/group_public/download.php/6462 (accessed 12.09.13). Parker, S.G., Flint, S.H., Brooks, J.D., 2003. Physiology of biofilms of thermophilic bacilli − Potential consequences for cleaning. Journal of Industrial Microbiology and Biotechnology 30, 553–560.

Relevant Websites www.meatami.com/ American Meat Institute. http://chemstation-chesapeake.com/index.php? option=com_content&view=article&id=46&Itemid=69 Chemstation Chesapeake − Meat Processing Chemicals. www.ehedg.org/ EHEDG, European Hygienic Engineering & Design Group. http://www.fao.org/docrep/003/x6557e/X6557E04.htm Food and Agriculture Organization − Slaughterhouse Cleaning and Sanitation. http://www.nsf.org/ NSF International. http://www.3-a.org/ 3-A Sanitary Standards, Inc.

ETHNIC MEAT PRODUCTS

Contents Biltong: A Major South African Ethnic Meat Product Brazil and South America China and Southeast Asia France Germany India and Pakistan Japan and Korea Mediterranean Middle East North America Poland

Biltong: A Major South African Ethnic Meat Product PE Strydom and B Zondagh, Animal Production Institute, Irene, South Africa r 2014 Elsevier Ltd. All rights reserved.

Glossary Enterotoxin (not to be confused with endotoxin) A protein toxin released by a microorganism that targets the intestines. Gamma radiation It is also known as gamma rays, denoted by the Greek letter g that refers to electromagnetic radiation of high frequency and therefore high energy per photon.

Introduction Biltong is a traditional South African meat snack consisting of strips of salted, flavored, and dried lean meat. The word ‘biltong’ is derived from the Dutch words ‘bil’, which means round or buttock, and ‘tong’ (or tongue), which describes the long strips of meat. For centuries, mankind has endeavored to preserve meat. Salting and drying of raw meat was a practice born of necessity by many of the forbearers who did not have any other facilities or methods with which to preserve meat. Through innovative upmarketing and subjection to modern processing and packaging technology, biltong has evolved from a food security type of commodity food to a marketdriven premium snack.

The Traditional Method of Making Biltong Biltong has probably been made since the 1650s when Jan van Riebeeck hosted a halfway house at the southern point of

Encyclopedia of Meat Sciences, Volume 1

Humectant A substance that absorbs or helps another substance to retain the moisture. Osmophiles Microorganisms adapted to environments with high osmotic pressures, such as high sugar concentrations. Water activity It is a measure of the availability of free water, and its value is governed by the degree to which ionic or other more weakly charged substances bind water.

Africa. Later, biltong became a staple protein source of the pioneers on their expeditions into Southern Africa (1700– 1800). During the Second Anglo-Boer War (1899–1903), Boer soldiers relied on biltong as a protein source when fresh meat from game and cattle became scarce. In earlier days, the whole carcass was used to cut biltong, but in modern times mostly muscles low in connective tissue from the round (buttock) and sometimes from the loin and tenderloin are used. In the mother tongue, biltong cut from the eye of the round (m. semitendinosus) is called ‘predikantsbiltong’ (Dutch for church minister's biltong), that from the fillet (m. psoas), ‘ouma se biltong’ (Dutch for grandma's biltong), and any cuts with high levels of connective tissue, are called ‘vrinnebiltong’ (Dutch for friend's biltong). Meat from relatively young and lean carcasses is preferred for making biltong, as fat does not preserve well and becomes rancid, whereas meat from old animals will produce tough, sinewy biltong. The meat is processed by first removing all excessive connective tissue and trimming excessive fat if necessary. Depending on the muscle type and drying conditions,

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the meat is usually processed into long strips varying between 25 and 100 mm in width. Coarse salt, in the proportion of 2–3%, is added by sprinkling the thin pieces and hand rubbing the thicker ones. Other spices, such as pepper and freshly roasted ground coriander, and ingredients such as brown sugar are often included as part of the traditional recipe. Sugar added at low levels prevents the hardening effect of salt without sweetening the final product (humectant function). Vinegar is sometimes sprinkled over the meat strips before they are packed in a container and left to pickle for 12–24 h. Brown or balsamic vinegar or wine or apple cider vinegar may be used. Excess salt is then removed by washing the pickled meat strips with a weak solution of warm vinegar water. This also helps to preserve the meat during the initial drying by delaying microbial growth. The salted meat strips are hung on small wire hooks on a piece of wire or a rod in the shade in a cool draughty place away from flies and dust. In humid environments, thinner strips are cut to prevent mold formation and spoilage. In addition, bicarbonate of soda is sometimes used to prevent spoilage, whereas saltpeter (a nitrate) is often added to bring out a red color in the final product through curing. Biltong can be consumed after it has lost 50% of its weight, but in the absence of chilling or freezing facilities, further drying is advised for prolonged preservation. At 50% weight loss, beef biltong is at its best with a dry brown layer on the outside and soft, moist red tissue underneath. Meat from different game species is also very popular for making biltong, but owing to its peculiar taste, it is preferred when thoroughly dried (460% weight loss).

Preservation, Storage, and Shelf Life of Biltong as an Intermediate Moisture Food According to definition, biltong can be described as an intermediate moisture food (IMF). An IMF is characterized by a moisture content of approximately 15–50% and a water activity (aw) between 0.6 and 0.85, which is less than what is normally present in natural fruits, vegetables, or meats but more than what is left in conventionally dehydrated products. In addition, IMF contains sufficient dissolved solutes to decrease water activity below that required to support microbial growth. As a consequence, IMF does not require refrigeration to prevent microbial deterioration. There are two factors of major importance to produce microbiologically stable and safe biltong, namely, the salt and moisture contents. These factors can actually be related to one another through the concept of water activity, or aw. The aw of microbiologically stable biltong should be less than 0.70, with pH 5.5. However, a wide variation in aw is encountered, because specific standards for processing of biltong do not exist. The aw of commercial biltong varies from 0.30 to 0.92 (average 0.74). Bacterial growth usually ceases at an aw of o0.75, where some yeasts and fungi continue to grow at levels as low as 0.62. A survey of the mycoflora of biltong indicated that moulds of the Aspergillus glaucus group were most frequently implicated in biltong spoilage. Although these osmophiles, which are capable of growth at low water activities, are not noted mycotoxin producers, their growth on biltong is nevertheless undesirable and results in economic losses. Studies indicated that yeasts are

the predominant component of the mycoflora of biltong. In addition, the risk of pathogenic contamination, Staphylococcus aureus and Listeria monocytogenes in particular, is also high because many consumers prefer biltong with moisture content higher than 40% (aw40.85). These conditions could favor the growth of these pathogens and the production of enterotoxins because both are tolerant of salt and reduced aw. Reasons for contamination are (1) Raw meat from abattoirs that may be significantly contaminated, (2) lack of proper hygiene practices by manufacturers, and (3) the frequent selling of an unpacked product together with raw meat in butcheries. In commercial biltong production, proper hygiene practices are, therefore, essential. Proper drying of products, if accepted by the consumer, will decrease initially high counts of microorganisms to levels acceptable for most food safety regulations. Alternative interventions include the use of gamma irradiation, and low levels of irradiation (≤ 4 kGy) even showed improved flavor development of moist biltong, which could normally have a bland taste.

Commercialization of Biltong Over time, biltong developed from a basic, staple, preserved food of pioneers and provisions of soldiers to a traditional food kept by farmers slaughtering their own cattle in the time before urbanization increased. Even during the earlier days of urbanization, biltong was a commodity mostly preserved by the local butcher, but today, it is increasingly becoming a branded delicacy that is grabbing more space on snack shelves. Biltong is still produced on the small scale for commercial purposes as well as for private use because of the fairly low entry costs in terms of facilities. However, it is believed that large-scale operations are more likely to survive price fluctuations of the required raw material (fresh, high-quality meat). More importantly, consumers are becoming ever more concerned about the quality and consistency of what is now becoming a luxury snack. Small-scale operations cannot offer the required quality standards or the required marketing and distribution backup. Furthermore, export opportunities are growing but are impossible to exploit without an EU and hazard analysis and critical control points (HACCP) certified factory. Although small-scale and domestic operators are using more modern procedures such as artificial drying methods in cabinets and tunnels, larger operations operate in factories with wet and dry restricted areas (adoption of HACCP and ISO 9001), sophisticated portioning and cutting machinery, drying rooms (four day turnover), and packaging and labeling machines. Today, interesting variations on the basic product offer the consumer a range of choices from the traditional biltong to spicy ‘snapstix’ (very dry and thin meat strips) to paper-thin tearing biltong (‘wafers’ or ‘leaves’). In addition, the basic flavor ingredients are complemented by hints of cloves, ginger, mace, garlic, chili powder, allspice, aniseed, and/or herbs such as thyme. Pineapple juice could be included in the manufacturing process to improve tenderness. Modern packaging methods, such as nitrogen flushing or vacuum packaging, ensure an extended shelf life, and the snack image is further promoted by offering different pack sizes from as small as

Ethnic Meat Products | Biltong: A Major South African Ethnic Meat Product 50 g. Long, thin perforated plastic packets allow moisture to evaporate before and after it is sold, but molds can still develop on the surface if the biltong is too moist. Apart from product development strategies, innovative marketing by larger producers also adds to biltong's commercial success. One such strategy has been to use television to capitalize on biltong's strong links with sport, especially rugby, in South Africa. Brand names such as ‘Halftime’ are used in this regard. From a traditional meat product born out of the need for food preservation, biltong has progressed through a production-driven commodity food to a market-driven and branded premium snack.

See also: Curing: Dry. Ethnic Meat Products: North America

Further Reading Atwell, E., 2003. Biltong wakes up. South African Food Review 30 (2), 15–19. Basson, D.S., 1970. The manufacture of ostrich biltong. Food Industries of South Africa 22 (12), 23.

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Burnham, G.M., Hanson, D.J., Koshick, C.M., Ingham, S.C., 2008. Death of Salmonella serovars, Escherichia Coli 0157:H7, Staphylococcus aureus and Listeria monocytogenes during the drying of meat: A case study using biltong and droëwors. Journal of Food Science 28, 198–209. Dzimba, Flávia J.M., Faria José de Assis, F., Walter, E.H.M., 2007. Testing the sensory acceptability of biltong formulated with different spices. African Journal of Agricultural Research 2 (11), 574–577. Nortjé, K., Buys, E.M., Minnaar, A., 2005. Effect of w-irradiation on the sensory quality of moist beef biltong. Meat Science 71, 603–611. Osterhoff, D.R., Leistner, L., 1984. Suid-afrikaanse bees biltong − weer eens onder die soeklig. Journal of the South African Veterinary Association 55, 201–202. Taylor, M.B., 1976. Changes in microbial flora during biltong production. South African Food Review 3 (2), 120–123. Van den Heever, L.W., 1972. The control of yeast on biltong with sorbic acid. Food Industries of South Africa 25 (5), 11. Van der Riet, W.B., 1976a. Studies on the mycoflora of biltong. South African Food Review 3 (1), 105–111. Van der Riet, W.B., 1976b. Water sorption isotherms of beef biltong and their use in predicting critical moisture contents for biltong storage. South African Food Review 3 (6), 93–96. Van der Riet, W.B., 1981. The preservation of biltong with sorbic acid. South African Food Review 8 (2), 63–69. Van der Riet, W.B., 1982. Biltong − a South African dried meat product. Fleischwirtschaft 62 (8), 1000–1001.

Brazil and South America F González-Schnake, Universidad de Concepción, Chillán, Chile R Nova, University of Nottingham, Nottingham, UK r 2014 Elsevier Ltd. All rights reserved.

Glossary Dried meat A method of meat preservation which can be achieved through dehydration of fresh meat. It is one of the most ancient methods of extension of shelf life used in meat. The process can be carried out with a very low level of investment (using only solar energy), or may be performed in a more mechanised environment, with various processing steps during the manufacturing process. Lamini group A group of mammals, which include the four species (alpaca, vicuña, guanaco, and llama) of South American camelids. Salting A preservation process that considers the use of salt, followed by a long period of drying.

Introduction Though the South American countries have many cultural similarities, they also have many differences between them. These differences are reflected in the variability of their meat products. Before the arrival of the Spanish, in 1492, the population in the Americas relied on their autochthonous fauna as a meat source, among these the most relevant were alpaca (Lama pacos), capybara (Hydrochoerus hydrochaeris), guanaco (Lama guanicoe), llama (Lama glama), nutria (Myocastor coypus), collared peccary (Tayassu tajacu), greater rhea (Rhea americana), lesser rhea (Rhea pennata), yacare (Caiman crocodilus yacare), tegu lizard (Tupinambis merianae), and green iguana (Iguana iguana). After the arrival of the conquistador European, domestic livestock were gradually introduced, these breeds are the ones that currently dominate the local market, and make South America the largest meat producer in the world. As well as the introduction of new domestic animals for human consumption, several meat products were brought from Spain, Italy, and Portugal. The production of these meat products, in some cases, was modified from the European original version to adapt the product to the local taste, climate, and availability of raw ingredients.

Sausage Product usually made from minced and/or ground meat from different food producing animals. In the traditional sausage production system, after processing, meat is stuffed in tripe, hence the typical cylindrical form of sausages. However, nowadays sausage casing can be done in natural or synthetic products (edible or not). Sausages may be preserved, amongst other methods by curing, drying, smoking, etc.; but they can also be fresh, hence needing cooking before consumption. Water activity (aw) Availability of water, defined as the ratio of the equilibrium of vapor pressure of water over the system and the vapor pressure of pure water at the same temperature.

To obtain a more homogenous effect, the treated meat is normally cut into small pieces. Though traditionally the meat used in this process has been sun-dried in the open, nowadays meat dryers are widely used, allowing a faster, hygienic, and more controlled process. In South America, as well as all around the word, dried meat products are still used in traditional cooking. Among these products the authors highlight carne de sol, cecina, and charqui.

Carne de Sol This is a dried meat product consumed in Brazil. It is produced from beef and sometimes from goat meat. The meat used to produce carne de sol is cut in thin strips, which are salted and then dried by exposing the meat to airdrying in a covered place from 2 to 4 days. Though the direct translation of its name means ‘sun meat,’ during its processing the meat is never exposed directly to sunlight. Instead, the meat is dried for a short time resulting not only in a hard and salty surface, which works as a protection barrier against microorganisms, but also keeping a juicy and tender inside. After this process the product can be stored without the need of refrigeration for a long period of time.

Cecina

Regional Products Dried Meats There has long been a requirement to preserve meat products in a way that allows their consumption at a later time. The most common, and oldest methods, to extend the shelf life of meat products are salting and drying, which by reducing the water activity (aw) of the product can help to extend shelf life and control the development of pathogenic microorganisms.

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This product is originally from Spain and it has become popular in Paraguay, Peru, and few other South American countries. It appears that the name is derived from the latin word ‘siccus,’ which means dry. It can be produced from beef and also from horse meat. As with other dry meats included in this section, traditionally cecina is salted and dried under the sun. However, this product is not necessarily dried in thin strips as entire meat cuts are used for the process.

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It is a ready-to-eat food product that does not need further processing.

modifications that have experimented to adapt to local ingredients and taste.

Charqui

Butifarra

The name of this product comes from the quechua ‘ch′arki.’ It has been produced in South America from before the arrival of the conquistador and can still be found in all South American countries. Originally, it was elaborated with meat from the native species of the Lamini group (llamas, alpacas, and guanacos) but nowadays, due to the introduction of new species during the colonization period, this product is produced mostly from beef and horse meat (Figure 1). The meat used for charqui is normally lean and is cut into thin pieces, followed by salting and drying under the sun. It can be consumed directly or as an ingredient in Latin American cuisine, mainly in dishes like soups and stews.

Butifarra is a traditional Spanish product that has become highly popular in the northern part of South America, especially in Colombia. This cooked fresh sausage is elaborated using beef, but butifarras made of chicken or pork can also be found. In some areas a mix of these three kinds of meats are used in its production. Lean meat, fat, and spices are mixed and then cased in edible tripe. Whereas the Spanish version of this product has a cylindrical shape, the Colombian one is more spherical. After casing, the butifarras are cooked in boiling water and can be consumed immediately because they do not require a ripening period.

Linguiça

Sausages Most of the most popular sausages in South America have European roots, not only Spanish and Portuguese but also with a large Italian and German influence. Chorizo, mortadela, salchichón, and salame are only few examples of how European immigrants influenced the development of the charcuterie in South America. Like many other sausages, the most popular products in South America, linguiça and longaniza, are generally served as part of a heavy meal, typically accompanied by rice, beans or potatoes. Feijoada, for example, is a traditional dish, very common in Brazil, which incorporates linguiça with beans and other foods. There are many types of meat products in South America with a wide variety of colors, flavors, and textures. These products constitute an important part of the local economy and tradition. Indeed, owing to the economic growth the elaboration has become more mechanized, but the processing is still based on the traditional manufacturing processes. This section will highlight four food products that stand out for either their penetration in the region and/or for the

Figure 1 Beef charqui.

Linguiça is a sausage that has its origin in Portugal and is very popular in Brazilian cuisine. There are many varieties of this product, so it can be produced from pork or from more than one kind of meat, can be smoked or not, can be cured or not, can be added with fat or produced more lean, and it can be cased in natural or artificial edible casing (Figures 2–4). Most commonly it is prepared with pork and up to 20% of beef plus the added seasoning. Linguiças must be stored for a period of time to develop the desired organoleptic characteristic of the product. In case the product is intended to be smoked, the storage time can be in the smoking chamber. After the ripening period, the product must be stored under refrigeration until commercialization.

Longaniza This meat product is originally from Spain; however, it is highly popular not only in South America, but also in Mexico, the Caribbean, and the southern regions of the USA.

Figure 2 Brazilian sausage Linguiça Calabresa. Courtesy of Eduardo A. Norkus (DVM).

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Figure 3 Brazilian sausage Linguiça carne frango (with chicken meat). Courtesy of Eduardo A. Norkus (DVM). Figure 5 Chillán′s longaniza, the most famous Chilean sausage.

Figure 6 Prieta or morcilla, sausage made from pork blood. Figure 4 Brazilian sausage Linguiça carne mista (pork and beef). Courtesy of Eduardo A. Norkus (DVM).

Longaniza (Figure 5) is a sausage filled with minced pork mixed with fat (usually belly pork) and spices. Normally natural intestine (from pig) is used for casing, but also synthetic collagen is used at times. Synthetic collagen casing is preferred in large companies, because it helps to standardize the product and reduces the risk of biological contamination in the food product. This sausage is normally long and relatively thin in size. It can be consumed raw if the longaniza has been cured and dried (a process that takes several months), but most commonly this sausage is commercialized as a fresh sausage, hence must be consumed cooked (traditionally fried or in barbecues).

Salchicha de Huacho This product, also known as salchicha huachana, is typical from Peru. Its elaboration is similar as in longaniza; hence, pork, pork belly, and spices are normally used in the elaboration of this product. After mixing the ingredients, either natural or synthetic edible collagen can be used for casing.

A peculiar characteristic of this sausage is its bright yellow color due to the use of annatto in its production. Annatto is a natural colorant used in food production, which is extracted from the South American plant Bixa orellana. Salchicha de Huacho is a fresh sausage and it must be cooked (usually fried) before consumption.

Miscellaneous Chunchul Chunchul is not technically a meat product, it is instead elaborated from the small intestine of cattle and its name and variations (Argentina, chunchuli; Chile, chunchules; Colombia, chunchurria; Peru, chinchulin) came from the quechua ch′ unchul (intestine). This product varies in its name and preparation across South America, but basically the small intestine of cattle is emptied and washed. The product can be presented as twisted and braided intestines, or similarly as a sausage. It must be cooked before consumption and it is very popular in barbecues.

Ethnic Meat Products | Brazil and South America Prieta or Morcilla Prieta (Chile) (Figure 6) also known as morcilla (Argentina, Peru) or rellena (Colombia) is a sausage made mostly of the blood from pigs. In some countries blood from cattle and/or goat is also used. It is a food product that was introduced to the region by Spanish settlers. In addition to the basic ingredient (blood) it can also contain fat, rice, nuts, and spices. The ingredients used will vary according to the country. Once the mix is ready, an edible casing (natural or synthetic) can be used. It can be consumed hot immediately after cooking, or cold; though the latest is normally blood sausages that have been dried and ripened before consumption.

See also: Drying. Ethnic Meat Products: Mediterranean. Sausage Casings. Sausages, Types of: Dry and Semidry

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González, F., Paulsen, P., Smulders, F.J.M., et al., 2003. Exotisches für die Fleischtheke. Fleischwirtschaft 10, 32–37. Judge, M.D., Aberle, E.D., Forrest, J.C., 1989. Principles of Meat Science, third ed. Dubuque, IA: Kendall/Hunt Publishing Co. 351 p. Manhoso, F.F.R., Rudge, A.C., 1999. Aspectos microbiológicos, físico-químicos e histológicos das lingüiças tipo frescal comercializadas no município de Marília/ SP. Higiene Alimentar, São Paulo 13 (61), 44. Saadoun, A., Cabrera, M.C., 2008. A review of the nutritional content and technological parameters of indigenous sources of meat in South America. Meat Science 80, 570–581. Salvá, B.K., Fernández-Diez, A., Ramos, D.D., Caro, I., Mateo, J., 2012. Chemical composition of alpaca (Vicugna pacos) charqui. Food Chemistry 130 (2), 329–334. Siguelnitzcky, W., 2003. Elaboración de charqui de guanaco (Lama guanicoe) en la Isla Tierra del Fuego, XII Región. Tesis Medicina Veterinaria. Universidad de Concepción, Chile. Facultad de Medicina Veterinaria. Soto, N., 1988. Alternativas de elaboración de charqui de Guanaco (Lama guanicoe). Tesis Medicina Veterinaria. Universidad de Concepción, Chile. Facultad de Ciencias Agropecuarias y Forestales, Departamento de Medicina Veterinaria. Toldrá, F., 2002. Dry-Cured Meat Products. Trumbull, CT: Food & Nutrition Press, pp. 1−238. Torres, E., Pearson, A., Gray, J., Ku, P.K., 1989. Lipid oxidation in charqui (salted and dried beef). Food Chemistry 32, 257–268.

Further Reading

Relevant Websites

Brasil, Ministério da Agricultura e do Abastecimiento, 2000. Instrução Normativa N° 22 de 31 de julho de 2000. Anexo XIV Regulamento tecnico de identidade e qualidade da linguiça colonial. Frentz, J.-C., 1982. L´Encyclopédie de la Charcuterie. Vesoul, France: Soussana. Garcia, F.A., Mizubuti, I.Y., Kanashiro, M.Y., Shimokomaki, M., 2001. Intermediate moisture meat product: biological evaluation of charqui meat protein quality. Food Chemistry 75 (4), 405–409.

http://www.fao.org/docrep/010/ai407e/ai407e00.HTM Food and Agriculture Organization of the United Nations (FAO). http://www.fao.org/docrep/010/ai407e/ai407e17.htm Food and Agriculture Organization of the United Nations (FAO). http://www.ccmv.ufpr.br/2011/EMYLI.pdf Universidade Federal do Paraná.

China and Southeast Asia HF Ho, SilverPeak Pte Ltd., Singapore r 2014 Elsevier Ltd. All rights reserved. This article is reproduced from the previous edition, volume 2, pp 702–705, © 2004, Elsevier Ltd., with revisions made by the Editor.

Glossary Angkak Red fermented rice powder. Soy sauce A condiment made from a fermented paste of boiled soybeans, roasted grain, brine, and Aspergillus oryzae

Introduction Chinese cuisine has become ubiquitous in most countries of the world. This article does not directly cover the various cuisines originating from China or nearby Southeast Asian countries as these are extensive and are more appropriately covered by the websites. Through trade many of the Asian cuisines, such as Indonesian, Malaysian, and Thai, have blended. This article covers the way various meat products are made and used. There are more than 100 different types of traditional Chinese meat products (TCMPs) in mainland China. Many of these products can also be found in Southeast Asian countries and in metropolitan cities where there is a sizeable ethnic Chinese population. These products can readily be produced in home kitchens as well as in restaurant kitchens. A few of the TCMPs are now manufactured in meat processing plants using the latest meat processing technology and machinery, while maintaining the characteristics of Chinese dietary customs and product formulations; examples include Chinese-style pork

or Aspergillus sojae molds. It originated in China in the second century BCE and spread throughout Asia and today is also used in Western cuisine and prepared foods.

sausages (Figures 1 and 2) and Jinhua ham. Many TCMPs are named after cities or geographical regions. For example, Jinhua is a city in Zhejiang province, which is in southeastern China and situated south of the Yangtze River Delta. As a result of the relatively low water activity (aw) of these meat products (e.g., the aw of the different grades of Chinesestyle pork sausages ranges from 0.59 to 0.71), a high degree of dehydration (e.g., Jinhua ham has a moisture content of 52% at 40 days postproduction, and 34% when 1-year-old) (Figure 3) and high cooking temperature, TCMPs are generally marketed unrefrigerated. A majority of Chinese dried meat products are in fact intermediate-moisture foods that are stable at ambient temperatures and can be consumed directly from the package.

Product Characteristics The bulk of TCMPs are made from pork, the most common meat of choice for the majority of the Chinese people. There

Figure 1 Unpackaged Chinese sausage.

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Ethnic Meat Products | China and Southeast Asia are also a few TCMPs that are made from beef, mutton, chicken, duck, rabbit, and game meat. The basic product formulation is a combination of different amounts of salt, sugar (cane sugar and malt sugar are commonly used), soy sauce (either light or dark), Chinese wine (e.g., rice wine and the rose wine Mei Kuei Lu Chiew), vinegar, and monosodium glutamate. Also included in the formulation is a variety of spices and seasonings including star anise, cinnamon, clove, fennel, nutmeg, ginger, orange peel, garlic, and green onion (scallions). A natural food coloring that is used in some TCMPs is red fermented rice powder (angkak). This is a product of rice fermented with the fungus Monascus purpureus. The addition of a small quantity of this powder, approximately 1.5–3 g per

Figure 2 Short Cantonese dried sausages.

Figure 3 Jinhua ham.

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kilogram of sausage meat, results in maximum red color, which is stable and retains the color in the final product. It is an excellent natural substitute for nitrite in meat curing solutions. Many of the dried or semidried TCMPs have a relatively high salt content of more than 4%. In the case of cured meat, for example, the Nan An pressed-cured ducks (Ban Ya), the salt content is as high as 9–10%. Another characteristic of Chinese dried meat is the sweet taste. For example, dried beef has a sugar content of 15%, and the sugar content of the different grades of Chinese-style pork sausages ranges from 10% to 25%.

Figure 4 Siu mei platter including roast pork (bottom), roast goose (top), smoked ham (left), and unroasted white cut chicken and jellyfish (center).

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To a very large extent, TCMPs are characterized by regional flavors: • The northern (Beijing-style) flavor has a long history from the Ming dynasty (AD 1368–1644). The products are characterized by a strong flavor and liberal use of many types of spices. Representative products are roasted mutton, and cooked and seasoned beef and pork. • The southern (Suzhou-style) flavor is characterized by a rich and heavy flavor tinged with sweetness from a liberal use of wine and sugar. Representative products are roasted meats and dried meats.

•

•

The Cantonese flavor is characterized by a sweet pleasant taste from the liberal use of sugar (Figure 4). The main processing method is drying by hot air or smoke generated from burning charcoal made of special fragrant wood. The products are brightly red colored. The best-known products are roasted suckling pigs and Cantonese-style Chinese sausages (lap cheong). Sichuan flavor (also Szechuan) cuisine is characterized by spiciness, the result of liberal use of hot chilli, black pepper, sesame oil, ginger, and huajiao (also known as Sichuan pepper, Pericarpium zanthoxyli).

Table 1 Class

Subclass

Some notable representative products

Cured products

Salted productsa

Salted pork legs Nanjing salted ducks La Roub Sichuan cured rabbit (Cha Si Tu)c Beijing Ching Jiang Rou (beef/pork) Wuxie pork ribs braised in soy sauce Hangzhouf Jiang Ya (whole duck) Shanghai five-spice pork Chinese bacon Smoked pig tongue Smoked chicken Peking ducks Cantonese Cha Shaog (pork) Yunnanh Fung Ji (wind-dried chicken) Taichang shredded pork/beef

Cured products Braised and seasoned products

Jiang Roud

Smoked and roasted products

Smoked products

Roasted products Dried products

Sausages

Wind-dried products Meat flossi (shredded meat) Barbecued meat slicesj Chinese-style sausagesk

Hams

Raw hams (Huo Tui)

a

Guangdong-type Wuhan-type Harbin-type Jinhua hamsl Southern hams Northern hams Yun hams

Salted products are raw products. La Rou are cured meat (pork, also beef and lamb) products produced in the last month of the Chinese lunar calendar. Guangdong, Sichuan, and Hunan La Rou are some of the better-known products. They are normally boneless products; some of the Hunan La Rou are bone-in. They are subjected to lengthy natural ageing and dehydration processes in the cold winter months. La Rou appears oily and shining on the surface; the fat is golden yellow and translucent, and the meat pinkish-red. Guangdong Guan Dao Rou is meat from the pig's hind quarter carved into the shape of a saber, 20 cm long and 1.5 cm thick (imagine the fat as the curved blade and the meat at the back of a saber). c Sichuan province in southwest China is renowned for its cured rabbits. The presentation of the product is unique, in the shape of a silkworm cocoon; thus the Chinese descriptive term Cha Si. d Jiang Rou are meats marinated in soy sauce. They have a strong soy sauce flavor. In addition to soy sauce, fermented black bean is also used in some products. e Wuxi is a city in eastern China, in Jiangsu province, and is near to Shanghai. The product is known for its salty-sweet taste and delicate aroma. f Hangzhou is the capital city of Jiangsu province in eastern China. g Cha Shao literally means ‘cooked in forks,’ so called because the pork strips are held in fork-like sticks and cooked in flames. h Yunnan province is the most southwest region of China, sharing borders with Myanmar, Laos, and Vietnam. i Meat floss (Rou Song), also known as shredded meat, is usually made from pork, beef, or chicken meat. The shredded dried meat is golden in color and has a distinctive flavor and sweet taste. Rou Song that come in pork and beef flavors tastes a little like beef jerky. The meat undergoes a process that includes chopping, steaming, frying, and shredding by hand. Soy sauce, sugar, fennel, ginger, and wine are used as seasonings. j Made of either pork or beef. Pork slices are the most popular. Also known as Rou Gan in China, and Bak Kua in Singapore and Malaysia. k There are more than 30 varieties of traditional Chinese sausages. They are raw, nonfermented products with an aw in the intermediate-moisture range (B0.75). According to the degree of sweetness, i.e., the amount of sugar added in the sausage formulation, traditional Chinese-style sausages can be divided geographically into three groups: (1) Harbin-type sausages from northern China province of Heilongjiang, which are characterized by a low sugar content of B1.4%; (2) Wuhan-type sausages from the central China province of Hubei, which have a moderate sugar level of B4%; and (3) Guangdong-type sausages from the southern Chinese province of Guangdong, which contain at least 6% sugar, often much more. The Chinese-style pork sausages typically contain large pieces of meat and diced fat ranging from 0.5 to 1 cm in size. l Jinhua ham is a premium meat product that has the excellent quality attributes of Kentucky country ham and Blue Ribbon Virginia ham in the United States. The hams are dry-cured in the winter season. After about 9 months, the hams are carefully shaped to ensure that the leg is straight and the hoof is sickle-shaped. They are then graded according to their appearance and saltiness. The four acclaimed unique properties of Jinhua ham refer to its color, aroma, taste and appearance, and thin skin and fine bones. b

Ethnic Meat Products | China and Southeast Asia

Classification of Traditional Chinese Meat Products TCMPs can be classified according to the animal species, product formulation, processing methods, or product characteristics. Table 1 gives a classification of TCMPs based on the combined criteria of processing methods and product characteristics. Curing of meat is done by dry rubbing or soaking, or a combination of both. Soaking is a common practice for small cuts where the meat is submerged in brine. A typical brine is composed of crude salt and some flavoring ingredients. As crude salt is normally contaminated with nitrate, no additional nitrate or nitrite is required to initiate the curing reaction. Braised and seasoned meats are cooked in marinades with soy sauce as the basic ingredient. Cooking is done first on high heat. The heat is then gradually reduced to medium or low. These products have a ‘melt-in-the-mouth’ characteristic. The different product formulations typically incorporate five different spices, each having a distinctive flavor: star anise, cinnamon, clove, prickly ash, and fennel seeds. Processing of hams traditionally involves slow fermentation (2–3 months) and long ageing (3–4 months). The total processing time can be up to 9 months. Finished products have a 55–60% yield.

Chinese and Related Cuisines The Eight Culinary Traditions of China are Anhui, Cantonese, Fujian, Hunan, Jiangsu, Shandong, Szechuan, and Zhejiang cuisines. However, there are also many styles of Chinese cuisine outside China that include Vietnamese, Singaporean, Malaysian, Indonesian, Indian, and American. There are a

Figure 5 A Chinese buffet restaurant in the United States.

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number of websites that cover these styles. In other words, Chinese cuisine is popular around the world wherever there is ethnic Chinese population. The use of meats such as pork, beef, and chicken were relatively limited in the past and in places like Vietnam and Cambodia, fish is the main protein. American Chinese food typically treats vegetables as a side dish or garnish, whereas traditional cuisines of China emphasizes the use of vegetables. The use of carrots and tomatoes (from the New World) is a latest addition. Native Chinese cuisine makes frequent use of Asian leaf vegetables like bok choy and kai-lan and puts a greater emphasis on fresh meat and seafood. Stir frying, pan frying, and deep frying tend to be the most common Chinese cooking techniques used in American Chinese cuisine (Figure 5), which are all easily done using a wok. The symptoms of a so-called Chinese restaurant syndrome or ‘Chinese food syndrome’ have been attributed to a glutamate sensitivity, but carefully controlled scientific studies have not demonstrated such negative effects of glutamate.

Conclusion TCMPs are representative of the Chinese people's rich cultural and culinary heritage and diversity. Much before scientific technology was applied in meat processing, the Chinese people had, through intelligent and creative manipulation of product formulations in step with the winter season's favorable weather conditions, produced many of the well-known products such as Jinhua hams and Chinese-style sausages. Hurdle technology in meat processing, elucidated by Leistner in 1985 is an important scientific development in improving the microbiological stability of traditional meat products. It has explained the scientific background for some of the traditional methods used in

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China, and Leistner has visited China and further improved the safety of some of the Chinese processing methods. Further improvement in the quality attributes of TCMPs by application of modern meat science and technology such as the hurdle technology in the industrial scale production will thus benefit the trade in these products globally.

See also: Curing: Brine Curing of Meat. Ethnic Meat Products: Biltong: A Major South African Ethnic Meat Product; Brazil and South America; France. Germany; India and Pakistan; Japan and Korea; Mediterranean; Middle East; North America; Poland. Microbiological Safety of Meat: Hurdle Technology. Smoking: Liquid Smoke (Smoke Condensate) Application. Traditional

Leistner, L., 1985. Hurdle technology applied to meat products of the shelf stable product and intermediate-moisture food types. In: Simatos, D., Multon, J. L. (Eds.), Properties of Water in Foods in Relation to Quality and Stability. Dordrecht: Martinus Nijhoff, pp. 309–329. Leistner, L., 1988a. Mould-ripened foods. Fleischwirtschaft International 1988 (1), 26–32. Leistner, L., 1988b. Shelf-stable oriental meat products. Proceedings of the 34th International Congress of Meat Science and Technology, pp. 470−475. Brisbane, QLD: CSIRO. Leistner, L., 1990. Fermented and intermediate-moisture products. Proceedings of the 36th International Congress of Meat Science and Technology, vol. III, pp. 842−855. Havana: Food Industry Research Institute, Cuba. Leistner, L., Gould, G., 2000. Hurdle Technologies − Combination Treatments for Food Stability, Safety and Quality. New York, NY: Kluwer Academic/Plenum. Savic, Z., Zhang, K.S., Savic, I., 1989. Chinese-style sausages. Fleischwirtschaft International 1989 (1), 35–40.

Relevant Websites Further Reading Ang, C.Y.W., Liu, K.S., Huang, Y.W. (Eds.), 1999. Asian Foods − Science and Technology. Lancaster, PA: Technomic. Dong, Y.C., et al., 1991. Considerations relevant to the formulation of national standard for the classification and nomenclature of meat products. Meat Research 1994 (4), 3–9. (in Chinese, a quarterly publication of the China Meat Research Center in Beijing). FAO, 1991. FAO Consultancy Report On Traditional Chinese Meat Products. Geneva: PAO. Ho, H.F., Koh, B.L., 1984. Processing of some Chinese meat products in Singapore. Proceedings of the 4th SIFST Symposium − Advances in Food Processing, Singapore, pp. 28−39. Singapore: Singapore Institute of Food Science and Technology.

http://en.wikipedia.org/wiki/Chinese_cuisine http://en.wikipedia.org/wiki/Cantonese_cuisine http://en.wikipedia.org/wiki/Szechuan_cuisine http://en.wikipedia.org/wiki/Chinese_sausage http://en.wikipedia.org/wiki/Vietnamese_cuisine http://en.wikipedia.org/wiki/Cambodian_cuisine http://en.wikipedia.org/wiki/Singaporean_cuisine http://en.wikipedia.org/wiki/Indonesian_cuisine http://en.wikipedia.org/wiki/Thai_cuisine http://en.wikipedia.org/wiki/American_Chinese_cuisine http://www.fao.org/docrep/010/ai407e/ai407e17.htm http://www.travelchinaguide.com/tour/food/chinese-cooking/meat-dish.htm

France C Lambel, Ceyrat, France V Santé-Lhoutellier, INRA, Saint Genès Champanelle, France r 2014 Elsevier Ltd. All rights reserved.

Glossary Appertization It is a thermal processing procedure which sterilizes perishables by heat (110–130 °C). Back pudding Sausage made with blood. Charcuterie Etymologically the term refers to ‘chairs cuites’ (cooked flesh). In its present meaning it represents products from meat processing.

Introduction Many of the meat products have been produced in France for centuries. These products and recipes constitute an important culinary heritage, part of the French gastronomy, and also a significant part of French local and national economy. Meat is a major component of French consumption. Traditionally, the two most common and popular ways to use meat are stews (e.g., braised meat dishes like beef bourguignon or veal blanquette) and ‘charcuteries’ (mostly prepared in a delicatessen with pork meat like salami, sausages, cooked ham, dry-cured ham, paté, rillettes, and black pudding). Typical French products and dishes with their characteristics and French names are described in this article.

Braised Meat Courses In France, before the era of modern breeds and agricultural specialization, the farmers were mostly looking for versatility in the livestock selection. Animals were taking part in field work, giving enough milk fat to make cheese, but were also meat providers at the end of their life. At that time, meat was generally pretty tough and was usually cooked slowly for a few hours and mixed with vegetables. In France, the meat was not roasted until the end of the nineteenth century and not grilled before 1945. This slow cooking by boiling allows the muscle collagen to turn into gelatin. Gelatin modifies the textural properties of the dish and mainly behaves as a thickener for dishes in a sauce. In fact, in France, any good stew should combine not only bones, fat, and meat but also a good supply of collagen through bone addition. The source of gelatin is mainly sourced from beef tail, foot, marrow bones, and back ribs. • Bones: they give taste to the dish and texture to the sauce. • Fat muscles: they give the taste. Flanken-style ribs (cut of meat taken from the short ribs of beef) as well as the trapezius muscle are often used. • Lean muscles: give chewing and volume to the dish, but they taste very neutral. Several cuts are used, such as beef

Encyclopedia of Meat Sciences, Volume 1

Collagen It is the fibrous protein constituent of bone, cartilage, tendon, and other connective tissue. It is converted into gelatin by boiling. Dry curing The process involving the use of cure (potassium nitrate or sodium nitrite) mixed with salt followed by a long drying.

chuck, aglet baroness, eye of round steak, and bottom round roast. • Stringy and sinewy meat pieces: these are gelatinous pieces. They give the moisture and the texture to the sauce. It takes approximately 5 h of cooking for these meat cuts to gelify their collagen and become softer. Several cuts are used, such as beef cheek, shank, and corned beef briskets. These three kinds of pieces in equal proportions will give a balanced and tasteful braised meat dish. France has accumulated lots of braised meat′s recipes with wide varieties of regional expressions.

With Beef/Bull • Bœuf mironton (mironton of beef): cooked in beef stock and braised in tomato sauce with pickles. • Bœuf bourguignon: like its name suggests it comes from Burgundy and is slowly cooked in red wine. • Beef carbonnade: it comes from the north of France and it is braised in dark beer. • Gardianne de taureau (traditional bull herd leader): from Camargue in the south of France: bull marinated in red wine with onions, bacon, and orange peel and then braised. • Pot-au-feu (boiled beef): cooked in water with onions, carrots, leeks, and potatoes. • Bœuf à la ficelle (beef with the string): fillet of beef hung with a string attached to a wooden spoon placed across the pan and cooked in water with turnips, carrots, and leeks.

With Veal • Blanquette de veau (veal blanquette) (Figure 1): this recipe is the favorite French meal in France; it consists in a veal stew with white sauce. Veal meat used for blanquette is a little expensive and has enough fat in parts (parties), so that the meat does not dry out during the cooking; cuts include height of rib, back of the knee or, breast of veal support, i.e., tendron (middle-cut breast of veal). Veal meats are cooked in a broth made of water, onions, carrots, leeks, garlic, and white wine. Then a sauce is made with a ‘roux’

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Ethnic Meat Products | France • Games: civet de lièvre (hare stew), civet de sanglier (wild boar stew): marinated in red wine (and cognac sometimes) with onions and carrots, then braised slowly in the wine of the marinade. • Innards: tripes à la mode de Caen (braised tripe Caen′s style): braised with carrots in white wine and tripes à la lyonnaise braised with onions in a tomato sauce.

Charcuterie (Delicatessen)

Figure 1 Streaky bacon with lentils.

Etymologically, the term refers to ‘chairs cuites’ (cooked flesh). In its present meaning, it represents products from meat processing. Meat preservation, based initially on salting and smoking, has been deeply connected with the development of ‘appertization’ combined with cold chain and packaging techniques.

Dry Sausages/Saucisson et Saucisse Sèche

Figure 2 Veal blanquette.

and in the cooking broth, mushrooms as well as lemon juice are added. The veal is served in the sauce. • Veal Marengo: diced veal stew with tomatoes, carrots, onions, mushrooms, veal broth, and white wine.

With Pork • kig ha farz breton: from Brittany, in the west of France: smoked pork breast and foreleg cooked with vegetables in water with a buckwheat flour dough cooked in a canvas bag in the meat broth. • La potée auvergnate (hotpot): from Auvergne in the center of France: pork breast and foreleg ham cooked for 2 h in water with cabbage, carrots, celery, leeks, onions, and potatoes. • Petit salé aux lentilles (streaky bacon with lentils) (Figure 2): From Auvergne: pickled pork slowly cooked with lentils in water.

With Other Meat • Rabbit: civet de lapin aux pruneaux (rabbit stew with prunes): it is slowly cooked with red wine.

There are ‘saucisson’ recipes dating back to the Roman Empire. In France, the first appearance of the word ‘saucisson’ (a word of Italian origin) dates from 1546 in a book by Rabelais and shows how the transalpine cuisine had already penetrated in France. It is made of animal′s gut stuffed with minced meat. The lining is generally composed of two-third of meat and onethird of fat added with salt, sugar, curing agents, and spices. The mix is stuffed into a casing for a mild ripening and drying of 3 months. The basic processing is still the same but mostly mechanized (to respond to mass consumption). During curing, the dry sausage acquires organoleptic qualities due to the physicochemical transformations of myoglobin, carbohydrates, fats, and proteins of the filling. The most commonly used meat is pork, but there are also ‘saucissons’ made from bull (e.g., in Camargue in the south of France) or wild boar, poultry, donkey, and pork liver (‘figateli’ sausage in Corsica). Being easy to preserve, the dry sausage is a very popular dish in France; it is consumed in all occasions and is served with drinks or for picnics.

Cooked Ham/Jambon de Paris and Dry-Cured Ham/Jambon Sec These products were invented by the Gauls. Although it was the product of early smoking and salting preservation specialists, the ham recipe was quickly taken over and adapted by other people. The ham is represented in some frescoes and stained glass windows of the Cathedral Notre Dame de Paris. It became the ‘star food’ of the Middle Ages and the basis of the rural nourishment because it could be preserved easily. Nowadays, in France, two kinds of ham are produced: • Cooked ham or jambon de Paris (Figure 3): this is the most popular delicatessen type food eaten in France. It represents almost 70% of the processed pork. Basically, it is a pork leg that has been deboned and reshaped, injected with brine, and then cooked in a flavored broth. It is sometimes

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Nowadays, ‘pâtés’ are mostly made from pork meat, liver, fat, and lean pieces for the moisture and texture.

Blood Sausage or Black Pudding/White Boudin (Boudin Noir/ Boudin Blanc)

Figure 3 Jambon de Paris.

cooked in a cloth sewn around the ham (jambon au torchon). It is commercialized with or without rind. • Dry-cured ham or jambon sec: many regions of France have their own ways of preparing such a ham. All these regions share a special climate: close to mountain with a draining wind. The quantities of salt and the time of curing vary according to the traditions. The drying adds the final touch and gives the characteristics and quality of cured ham. The ham′s weight ranges from 5/6 kg to 9 kg depending on the region. In France, the most renowned hams are Jambon de Bayonne, Jambon d′Auvergne, and Jambon de Savoie. Bayonne ham enjoys EU Protected Geographical Indication (PGI) status. This certification requires professional processors to comply with specifications that provide the consumer with a finished product of optimal quality. Proteolysis in dry-cured ham occurs throughout processing but at different rates and to varying extents depending on salt penetration and water migration. The processing of Bayonne hams, which lasts 9 months, follows the sequence: salting, settling, oven drying, air drying, fat covering, and ripening.

Black pudding, of red-brown hue, gets its color from blood from which it is made. The ingredients are put into gut/intestines and cooked. There are as many recipes as regions of France. Pork butchers use more or less spices and add them depending on the region, for example, bread crumbs, Swiss chards, spinach, fresh herbs, flour, eggs, cream, and pig′s rind or foot. Black pudding is one the oldest known deli foods. It was invented in the antiquity by a Greek cook named Aphtonite. ‘Boudin’ blanc, for its part, is made from white meat (poultry, veal, pork, and pork fat). ‘Boudin’ (black or white) is still much being appreciated by French people. In 2002, as much as 14 730 tons of black pudding and 6962 tons of white pudding were produced.

Conclusion The French cuisine offers a huge variety in the names of dishes and in the way they are prepared and these traditions are part of the culinary traditions of French people. The cuisine also is underpinned by the way the meat is produced on the land, especially for each particular agriculture region, the stories surrounding the way the dishes first were created, the traditions accompanying the dish′s development, and how the cuisine was modified in the past to take account of seasonality. The two main traditional ways to use the meat in France are meat dishes braised in sauce/stock and ‘charcuteries’ (delicatessen). The variety of names and variability across the country associated with these aspects of the French meat cuisine are difficult to cover fully. This article provides an overview of the most famous ones.

Pâtés/terrines/Rillettes In the Middle Ages, terrines and pâtés were distinguished by their mode of cooking: terrines were cooked in clay (terre) containers, which explain their name. Pâtés (pies) were baked in dough not necessarily edible at that time. This crust was very thick to protect the stuffing during cooking and transport. Over the years, each province has developed its ‘pâté’ recipe typical of its land: • pâté Rennais (de Rennes in the west of France) is traditionally made with pork meat and cooked in the oven. • In the seventeenth century, the Picardie region was deemed to be well stocked with game. This region is one of the richest regions in France in pâtés and terrines′ recipes: Duck pâté d′Amiens, partridge pâté de Montdidier, and also hare and woodcock pâtés.

See also: Curing: Brine Curing of Meat; Dry. Ethnic Meat Products: Mediterranean. Ham Production: Cooked Ham; DryCured Ham. Sausages, Types of: Dry and Semidry. Smoking: Traditional

Further Reading Daumas, D., 2008. La cuisine des abats. Editions Sud-Ouest, 62 pp. Dumas, D., Imbertèche, H., 2010. Ris, cœurs, foies & autres abats. Editions Cuisines des Pays de France, 125 pp. France, B., Vitaux, J., 2008. Dictionnaire du Gastronome. Editions Presses Universitaires de France, 800 pp. Reynaud, S., 2012. Le livre de la tripe. Editions Marabout, 192 pp.

Germany M Gibis, J Weiss, and A Fischer, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse, Stuttgart, Germany r 2014 Elsevier Ltd. All rights reserved.

Glossary Ammerländer Schinken/Knochenschinken/ Dielenrauchschinken/Katenschinken Dry-cured ham from the northwestern region of Lower Saxony in Germany. Badisches Schäufele Cooked, cured, and smoked pork shoulder produced typically in Baden (Germany). Bayerischer Leberkäse Coarsely or finely chopped emulsion-type meat loaf produced by roasting (Germany). Braunschweiger Mettwurst Sliceable fermented sausages from a region around the town Braunschweig (Germany). Eichsfelder Feldgieker Fermented dry-cured and sliceable sausage produced by air drying from a region of Central Germany; veal bladders are used as casings. Frankfurter Würstchen Cured emulsion-type sausages with sheep casings and a typical smoky flavor and color from Frankfurt am Main (Germany). Göttinger Feldkieker Fermented dry-cured and sliceable sausage produced by air drying from an area around the town Göttingen (Germany) and using a bladder as casing. Göttinger Stracke Fermented dry-cured and sliceable sausage produced by air drying from an area around the town Göttingen (Germany). Greußener Salami Long-term fermented sausages produced in Thuringia (Germany). Halberstädter Würstchen Cured and intensively smoked emulsion-type sausages with sheep casings from Halberstadt (Germany) mainly sold as conserved products. Hofer Rindfleischwurst Spreadable fermented and smoked sausages containing beef and backfat from a region near the Bavarian town Hof. Holsteiner Katenschinken/Katenrauchschinken Drycured and cold smoked ham from the federal state of Schleswig-Holstein (Germany). Kassler Cooked, cured, and smoked pork loin or neck. Knacker Emulsion-type sausage (Knockwurst) with a typical smoking flavor and color. Leitsätze für Fleisch und Fleischerzeugnisse des deutschen Lebensmittelbuches Part of the German Food Codex containing guidelines for German meat and meat products. Münchner Weißwurst Noncured emulsion-type sausages with hog rounds as casings from Munich (Germany). Nürnberger Rostbratwurst/Nürnberger Bratwürste Noncured emulsion-type sausages in sheep casings (length

Introduction More than 1500 different kinds of meat products and sausages are produced in Germany. The different types of meat products are defined by the raw materials used, their special quality

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7–8 cm) for frying from the area around Nuremberg (Germany). Pfälzer Leberwurst Spreadable and noncured liver sausages with a typical spicy flavor of marjoram from Rhineland-Palatinate (Germany). Pfälzer Saumagen Coarse emulsion-type sausage filled in hog stomach from Rhineland-Palatinate (Germany) containing pieces of blanched potatoes and pork, and bacon. Regensburger Coarsely or finely chopped emulsion-type sausage from the region around the town Regensburg (Germany). Roter Schwartenmagen Blood sausage with pieces of head pork. Rügenwalder Teewurst Spreadable fermented sausages containing honey or glucose syrup. Schwarzwälder Schinken Dry-cured ham with an intensive cold smoking flavor and dark color from the region of Black Forest (Schwarzwald, Germany). Schwarzwurst Blood sausage. Stuttgarter Schinkenwurst Coarse emulsion-type sausage. Teewurst Spreadable fermented sausage produced by a finely or coarsely chopped batter. Thüringer Leberwurst Spreadable and cured liver sausage with a typical flavor of marjoram from Thuringia (Germany). Thüringer Rostbratwurst Medium finely comminuted sausage for frying and grilling without nitrite curing salt as well as with an intense marjoram flavor from Thuringia (Germany). Thüringer Rotwurst Blood sausage with a spicy clove and marjoram flavor from Thuringia (Germany) containing precooked cured cubes of lean meat, heart, or tongue. Weißer Schwartenmagen Cooked sausages produced by head pork, jowl, and jellied brawn. Westfälischer Knochenschinken Dry-cured ham produced by a long-term ripening with bone-in and with a mildly smoky and spicy flavor from Westphalia (Germany). Wiener Cured emulsion-type sausages in sheep casings with a typical smoky flavor and color from Frankfurt am Main (Germany). Ansbacher Preßsack Cooked sausages produced by cured head meat, jowl, and jellied brawn from the region near the Bavarian town Ansbach (Germany).

attributes as well as by the key analytical values. A complete list of products and their specifications can be found in the ‘Leitsätze für Fleisch und Fleischerzeugnisse des deutschen Lebensmittelbuches’, a section of the German Food Codex containing guidelines for German meat and meat products.

Encyclopedia of Meat Sciences, Volume 1

doi:10.1016/B978-0-12-384731-7.00196-3

Ethnic Meat Products | Germany Some German meat products are traditional ethnic products that are typical of a specific region (Figure 1). An overview of the principal classification of German meat products, together with examples, is provided in Table 1. When a product acquires a reputation that extends beyond the national borders of the region or country of its origin, it may find itself in competition with similarly named but counterfeit products that pretend to be genuine German sausages. In 1992, the European Union, therefore, established authentication systems such as the ‘Protected Designation of

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Origin,’ ‘Protected Geographical Indication’ (PGI), and ‘Traditional Speciality Guaranteed’ labels to promote and protect the authenticity of ethnic food products. As an example, ethnic meat products that have been granted PGI protection, or have PGI protection applications pending, are shown in Table 2. These ethnic meat products may also simultaneously be registered as trademarks at the German Patent and Trade Mark Office, with trademarks being linked to the geographical origin of products. However, most of the ethnic meat products in Germany are not protected by such authentication systems. Below, select traditional ethnic products that are of particular popularity in Germany are presented in more detail.

Dry-Cured Ham Schwarzwälder Schinken (Black forest ham)

Figure 1 Some typical German meat products: (clockwise from top left) Schwarzwälder Schinken, Pfälzer Leberwurst, Thüringer Rotwurst, Stuttgarter Schinkenwurst, Rügenwalder Teewurst, Nürnberger Rostbratwürste, (down left to right) Münchner Weißwurst, Nürnberger Rostbratwurst, Rügenwalder Teewurst. Table 1

The process used to produce ‘Schwarzwälder Schinken’ is shown in Figure 2. The raw material consists of deboned rear pork shanks without or with topside. It is obtained from pigs raised on farms located in the black forest region of Germany dedicated to the production of raw material for ‘Schwarzwälder Schinken’. The farms are regulated with respect to feed type, raising conditions, and pig species to ensure a top quality of the raw material. After slaughtering, the raw material is subjected to a quality analysis before use. Parameters that are controlled include pH (o6 to ensure absence of dark, firm and dry – DFD meat), core raw material temperatures of below 4 °C, quality of the cuts as the removal of excess backfat, their weight, and an appropriate ratio of lean meat to set backfat (approximately 20% of lean meat). The pH value in particular is a decisive factor for determining whether the raw material is

An overview of the classification of ethnic German meat products

Meat products

Description

Examples

Dry-cured ham

Salted and cured ham (smoked or air dried)

Cooked cured meat products

Different cuts (ham, loin or shoulder) of pork, beef, or veal

Fermented sausages (raw sausages)

Dry cured sausages (sliceable)

Cooked sausages (emulsion-type sausages)

Finely or coarsely minced and cured sausages (spreadable) Finely chopped (usually heated for consumption)

Schwarzwälder Schinken (Black forest ham), Ammerländer Schinken, Holsteiner Katenschinken, Westfälischer Knochenschinken Kassler (cured and smoked pork loin), Badisches Schäufele (cured and smoked pork shoulder) Greußener Salami, Göttinger Stracke, Göttinger Feldkieker Rügenwalder Teewurst, Braunschweiger Mettwurst, Hofer Rindfleischwurst Frankfurter (frankfurters), Wiener, Knacker (knockwurst), Bayerischer Leberkäse (meat loaf), Halberstädter Würstchen, Münchner Weißwurst Regernsburger, Bayerischer Leberkäse (meat loaf), Stuttgarter Schinkenwurst Pfälzer Saumagen (added with pieces of pork and potatoes) Thüringer Leberwurst, Pfälzer Leberwurst Thüringer Rotwurst, Pfälzer Blutwurst, Roter Schwartenmagen, Schwarzwurst Ansbacher Presssack, Weißer Schwartenmagen, Weißer Presssack Nürnberger Rostbratwurst, Thüringer Bratwurst/Thüringer Rostbratwurst

Coarsely chopped Addition of pieces of meat Cooked sausages

Liver sausages (spreadable) Blood sausages Head meat, jowl (jellied brawn)

Sausages for frying

Fried, broiled, or grilled sausages

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Table 2

Ethnic Meat Products | Germany An overview of the protected geographical indication (PGI) of meat-based products in Germany

Dossier number

Designation

Registration date

DE/PGI/0005/0703 DE/PGI/0005/0721 DE/PGI/0005/0713

Göttinger Stracke Göttinger Feldkieker Holsteiner Katenschinken/Holsteiner Schinken/Holsteiner Katenrauchschinken/Holsteiner Knochenschinken Hofer Rindfleischwurst Westfälischer Knochenschinken Halberstädter Würstchen Eichsfelder Feldgieker Thüringer Leberwurst Thüringer Rostbratwurst Thüringer Rotwurst Nürnberger Bratwürste; Nürnberger Rostbratwürste Greußener Salami Schwarzwälder Schinken Ammerländer Schinken; Ammerländer Knochenschinken Ammerländer Dielenrauchschinken; Ammerländer Katenschinken

27/07/2011 27/07/2011 31/01/2012

DE/PGI/0005/0722 DE/PGI/0005/00854 DE/PGI/0005/0615 DE/PGI/0005/0773 DE/PGI/0005/0222 DE/PGI/0005/0223 DE/PGI/0005/0224 DE/PGI/0005/0184 DE/PGI/0017/1266 DE/PGI/0017/0686 DE/PGI/0017/1223 DE/PGI/0017/1225

Ham (deboned) Sodium chloride + nitrite + nitrate + spices Dry curing (7 days)

Pickle curing (20% solution)

Ageing (4 °C, 3–4 weeks)

Smoking (< 30 °C, 2 weeks)

Over pine branches + pine saw dust

Final ripening (12 °C, rH 50%, 3–4 days) Figure 2 Production process of Schwarzwälder Schinken.

suitable for use in the production of ‘Schwarzwälder Schinken’ as the surface of hams may become slimy and gooey after drying and the consistency gummy if the pH value of the raw material exceeds 6.0. Another very important factor is to correctly trim the raw material, which in turn determines the ratio between fat and lean meat. The salt and spice mixture used contains nitrite curing salt and/or nitrate and a characteristic spice blend composed of, for example, juniper, whole pepper, garlic, and coriander. Each ham is dry-rubbed with the spice and salt blend, and multiple hams are then stored together in a

04/02/2011 09/04/2013 09/10/2010 15/05/2013 18/12/2003 18/12/2003 18/12/2003 16/07/2003 09/04/1998 24/01/1997 24/01/1997 24/01/1997

sealed container. During storage, salt gradually diffuses into the meat. Every second day, hams are turned. Within 3–4 days, a natural brine begins to form and accumulate in the container. As soon as a natural brine has formed, additional brine is added to completely cover hams. The process of brining is completed within 2 weeks. The hams are then removed from the container, washed, and dried. The hams are then laid on a metal grid or hung and allowed to age in a controlled environmental chamber at a temperature of o5 °C and a relative humidity of 60–80% for 2 weeks. During the aging step, moisture is lost, and salt concentration profiles are equilibrated throughout the ham, both key steps to ensure the microbiological safety of hams. After aging, the hams are finally cold smoked for 2–3 weeks at 20–25 °C using pine wood that is the hallmark of the black forest region. The hams are then again aged at a relative humidity of ~50% at 15 °C. After completion of the aging process, hams have lost ~25% of their initial weight. The salt content of the final product must not exceed 15% on a dry matter basis and the ratio between fat and lean meat must not exceed 25% with a water-to-protein ratio of 2.2:1. The final product is characterized by a smokecovered black surface, a dark-red interior color, a tender texture and an intense smoky and aromatic but not overall salty flavor. In former times, the production of ‘Schwarzwälder Schinken’ was only possible in the black forest, a forest-dense region in the southwestern part of Germany with general altitudes of approximately 800 m above sea level as the climatic conditions there required for the production of hams were similar to those described above.

Ammerländer Knochenschinken This special dry-cured ham originated in or near Oldenburg, a town in the northwestern region of Lower Saxony. The raw material from a special variety in this region consists of rear pork shank with topside containing no bone and should weigh ~12 kg. Initially, the raw material is dry cured with nitrite curing salt, sea salt, brown sugar, pepper, juniper, and pimento for a minimum of 10 weeks by manually dry-rubbing the salt and spice mix into the meat once a day. After curing,

Ethnic Meat Products | Germany

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the product is hung for approximately 2 weeks for aging. Temperature and humidity conditions during curing and aging should follow standard protocols for ham processing. The hams are then weakly and preferably cold smoked with beech shavings at a high relative humidity for ~10 weeks. A further aging step follows under the above conditions for ~6 weeks. Taken together, the process takes 9 months. The ham has a final water-to-protein ratio of 2.5:1. Owing to the use of beech wood, the surface of products attains a slightly golden color whereas the interior is intensely red; has a very tender texture; and a very lightly smoky and mildly salty flavor.

open air that is interrupted by the above-mentioned cold smoke process for a total of 5 months. The entire production takes between 6 and 18 months, depending on the sensory quality of the product such as tenderness. The product is sold with the bone being removed. ‘Westfälischer Knochenschinken’ has a characteristic intensely golden surface and a dark red interior. Its flavor may be described as being mildly smoky and spicy. The texture is very tender.

Westfälischer Knochenschinken

This salami is produced in Thuringia, a state on the southeast of Germany, which was subjected to the rule of France in 1897. In contrast to the conventional rapid production of salami (Figure 3), in which starter cultures or glucono-δ-lactone are used to quickly lower the pH value, allowing for a short fermentation time of less than 4 weeks. The manufacturing of the ‘Greußener’ salami involves a long-term fermentation process that requires a minimum of 5–6 weeks. The raw material for this salami consists of high-quality beef void of sinews and free of fat, and roughly trimmed pork and backfat. The spices used include pepper, garlic and a variety of other spices such as nutmeg. The meat is coarsely ground using a meat grinder and further processed on a bowl chopper. To obtain a well-defined fat distribution in meat without causing the fat to be emulsified, the material should be partially frozen before chopping. After processing on the bowl chopper, the meat batter is filled into cellulose casings at a temperature of −2 °C to −4 °C, hung in a smoking chamber and cold smoked at intervals using beech wood for 4–5 days. Temperature is controlled and the pH is monitored during the smoking

Fermented Sausages Greußener salami

‘Westfälischer Knochenschinken’ is a highly traditional product that traces its roots back to the twelfth century. In those early times, the production could only be carried out during the cold and moist winter months. The raw material again consists of a whole, bone-in pork hindquarter. In former times, the pigs were fed a special accord diet that was said to yield especially tender and dark red colored pork. The ham is dry-rubbed with a mixture of nitrite curing salt, potassium nitrate and sugar and stored in a closed container with a total curing time of 3–6 weeks to allow for the development of a natural brine. Unlike the production of ‘Schwarzwälder Schinken’, no additional brine must be added. Once a week during the curing, the hams are turned and resalted with the curing mixture. After 3 weeks, the brine is removed and the hams again left to cure for a period of 3 weeks. Afterwards, they are washed, dried and scrubbed and hung in chambers to allow surface moisture to evaporate and are subsequently smoked. Smoking involves either a long-term cold smoke process with beech wood or an alternating aging process in the

Beef (cooled)

Grinding

Beef/Pork (frozen)

Back fat (frozen)

Chopping Spices + starter cultures

Mixing/ Chopping

Stuffing

Ripening/drying/smoking (1–6 weeks, 18–24 °C, 90–75% rH)

Storing (16–18 °C; 70% rH) Figure 3 Production process of sliceable fermented sausages (Salami).

Sodium chloride + nitrite + nitrate + curing agents

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Ethnic Meat Products | Germany

Lean meat (0–2 °C)

Chopping

Sodium chloride + nitrite + curing agents + spices

Back fat

Chopping

Mixing/Chopping (< 16 °C)

Stuffing

Ripening (2–4 days, 18– 24 °C, 80–85% rH)

Cold smoking (18–20 °C, 80–85% rH, 4–12 h) Figure 4 Production process of spreadable fermented sausages (Teewurst).

process. After smoking, the salami is ripened for 4–5 weeks to a final weight of 65–70% of its original weight. This salami has a mild pepper aroma, a stable dark red color and a very firm texture, which allows for the sausage to be easily and thinly sliced.

Rügenwalder Teewurst In contrast to the production of other spreadable fermented sausages (Figure 4) that belong to the general class of ‘Teewürste’, the ‘Rügenwalder Teewurst’ contains honey or glucose syrup. The Rügenwalder Teewurst is made from beef and/ or pork with a low content of connective tissue and a fat content of below 45%. Before processing, the raw material is chilled to  1 °C to +2 °C. After mincing and chopping of the lean meat, fat is added. The mixture is then processed on the bowl chopper to attain a finely dispersed (creamy) batter. The batter is filled into a cellulose casing and fermented for approximately 24–48 h at 16–24 °C at a relative humidity of 80–90%. Sausages are then cold smoked at 18 °C, until the products attain an intensely smoked and spicy flavor and a deep red color.

Cooked Sausages Emulsion-type sausages Germany is known for its wide variety of sausages but particularly for those that belong to the category of emulsified sausages. Some emulsified sausages are only salted with sodium chloride, such as the ‘Gelbwurst’, or the ‘Münchner Weißwurst’, but most sausages such as the ‘Lyoner’, the ‘Halberstädter Würstchen’, or the ‘Frankfurter’ contain nitrite curing salt.

Halberstädter Würstchen Halberstadt is a town in the central region of Germany and the traditional manufacture process of the ‘Halberstädter Würstchen’ dates back to more than 100 years. This sausage is a cured emulsion-type-sausage made from finely chopped pork (~45%), beef (~15%), backfat (~15%), and ice (~25%). The batters are filled in thin, tender natural sheep casings (rounds) and are hot smoked for 40–50 min at an average smoking temperature of 60–75 °C. Direct firing with an underfloor furnace fed with beech wood causes the temperature in the smoking chamber in intervals to briefly reach temperatures above 110 °C. This also causes a continual reduction in relative humidity (o25%) to take place. Characteristic features of these sausages are their brown color and an unmistakable, intense smoky flavor. The sausages are mainly sold as a conserved product, for example, in a glass or metal jar.

Frankfurter Würstchen In Germany, ‘Frankfurters’ have been known since the thirteenth century and have been protected under the name ’Frankfurter Würstchen’ since 1860. The name has been exclusively used for such sausages since 1929. A butcher from Frankfurt, Johann Lahner first manufactured these sausages in Wien and, because of this, they are also known as Wiener or Wiener Würstchen in Germany. Today and, in contrast to the original ‘Frankfurters’, Wieners are manufactured from pork and beef whereas Frankfurters are made with pork only. They are cured emulsion-type-sausages with a finely chopped batter consisting of ~45% lean and desinewed pork, 25% fat and 30% ice filled in sheep casings (rounds). The sausages have a mildly spicy and smoky flavor and a golden-brown color, a fact that is based on the addition of white pepper and nutmeg

Ethnic Meat Products | Germany

Lean pork (2–4 °C)

Backfat (2–4 °C)

Grinding

Grinding

Sodium chloride + nitrite + 2/3 ice

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1. Mixing/Chopping (< 11 °C) 2. Mixing /Chopping

1/3 ice + curing agents + spices

(72 °C 50 and up to 400

150

> 400 and up to 1500

200

Figure 2 Welfare aspects of the main systems of stunning and killing the main commercial species of animals. Reproduced with permission from European Food Safety Authority Journal (EFSA), 2005. Opinion of the Scientific Panel on Animal Health and Welfare (AHAW) on a request from the Commission related to welfare aspects of the main systems of stunning and killing the main commercial species of animals. EFSA Journal 45, 1–29.

Table 1

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manual cutting of the blood vessels is permitted. For Halal slaughter, it is dependent on the certifying body on whether or not birds may be stunned before the slaughter process. The bleedout phase takes anywhere between 2 and 5 min, depending on bird size, etc. During the process, approximately 35–50% of the total blood is lost. Other factors affecting blood loss include the stunning method used and the time interval between stunning and bleeding. It is important to note that a poor bleedout can increase the prevalence of carcass downgrading conditions due to bloodspots and, in particular, engorged or hemorrhagic wing veins, which leads to red wing tips and decreased shelf life.

Scalding In commercial abattoirs, scalding is done in a continuous manner whereby the birds are dipped in a single or multistage scalding bath while suspended from a moving shackle line. There are three commonly employed scalding schemes (Table 1): selection of one over another depends on the degree of difficulty in removing the feathers, the chilling method that is to follow (water and air), and the age of the birds. Soft scalding (50–55 °C) is commonly used for broilers and turkeys. The temperature needs to be closely monitored because a temperature that is less than 50 °C can lead to bacterial contamination or inefficient feather removal. Higher scalding temperatures (60–64 °C) not only are better for loosening feathers from their follicles but are also harshest on the skin (the outer layer of the skin, epidermis, becomes loose and is later removed during the plucking operation). The removal of the epidermis can result in discoloration of the skin if it is dehydrated during subsequent air chilling. In addition, hard scalding can cook the breast meat where the skin is very thin and leads to stripes on the breast meat that has been referred to as tiger striping. However, hard scalding is the only satisfactory way to release the feathers of waterfowl. Generally speaking, hard scalding does not cause as much discoloration in the thick skin of waterfowl as it does in young poultry. Soft scalding is commonly used for young broilers and turkeys because it does not damage much of the epidermis and allows relatively easy feather removal. Adequate agitation of the scald water and uniform temperature are essential to insure good feather removal. Careful equipment design is required for meat hygiene. Maintaining and controlling the temperature is one of the key features to keep the bacterial load under control. Another means is the use of a counterflow design (clean water introduced at the exit end of the tank, and water flow toward the entrance where the more contaminated birds are introduced). Installing a multistage scalding tank system can further reduce contamination problems; this consists of two to four

Recommended scalding schedules for defeathering

Technique

Water temperature (°C)

Time (s)

Used for

Hard scalding Medium/subscalding Soft/semiscalding

460 54–58 50–53

45–90 60–120 60–180

Waterfowl Mature birds Broilers, roasters, and young turkeys

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Slaughter-Line Operation | Poultry that the breast meat is tender. Breast meat deboning times for electrically stimulated carcasses are highly variable (30 min– 6 h) and depend on the bird size, parameters of the electrical stimulation unit, and many additional factors, such as customer, product application, and company standards.

Feet Removal During feet removal, the knee joint is positioned by guiding bars on an angle along the shackle line, and the feet are cut off by a circular rotating blade at the hock joint. Cutting through the bone can result in dark/red color in the chilled bird and almost black in the cooked product. Some of the new automated leg cutters first bend the leg and then perform a small incision, which allows further bending before cutting through the joint with a rotating circular blade. Feet are separated into two quality classifications that consist of those with defects including footpad lesions and those with dark color.

Rehanging

Figure 3 Side view of rubber fingers mounted on rotating disks and used for picking/plucking poultry feathers.

water tanks, where the carcasses are moved from the initial, more contaminated bath, to the cleanest bath at the end.

Feather Removal In large processing plants, feather removal is done by mechanical pickers/pluckers equipped with rubber fingers that rub the feathers off the carcass. In a continuous operation, this is done while the carcass is hanging upside down on the shackle line between two and three sets of rotating disks equipped with rubber fingers (Figure 3). The fingers are made out of rubber and contain a certain degree of lubricating agent that controls their hardness and elasticity. The elasticity and length of fingers varies, depending on the task required, the machine speed, etc. The fingers can also be mounted on drums that rotate toward the center. The distance between the two sides is adjusted to accommodate size variations.

After removal of the legs, the carcasses are usually transferred to another line because the broilers need to be hung by the knee joints, and this reduces contamination because the dirty shackles that are used for the live birds are replaced. Broilers are generally hung by their hocks so that they are 6–8 in. apart on shackle lines. An automated rehanging device can consist of a large wheel (carrier) with slots for holding the birds from underneath the knee joints and a device to push them into the evisceration line. The advantages of using automated rehanging equipment include labor savings and better hygiene.

Evisceration This process refers to opening the body cavity and withdrawing the viscera (the intestines, gizzard, gallbladder, and crop). In semiautomated or fully automated evisceration processes, the first step is to cut around the cloaca, using a circular rotating blade. Some of the new devices are equipped with a vacuum device so that potential fecal contamination is reduced, and the cutting device is usually rinsed after each insertion. The viscera are then scooped out from the body cavity and remain attached to the body for inspection purposes. Some of the new automated equipment allows total viscera separation immediately after withdrawal and placement on a parallel line. This can further improve the hygiene of eviscerated carcasses. Once the viscera pack is exposed or removed, the birds are inspected.

Electrical Stimulation Inspection Many commercial plants have adopted electrical stimulation after either the bleeding or the picking steps. Either high- or low-voltage electrical stimulation can be used to speed up rigor mortis so that breast meat can be deboned more quickly than the 4 h postmortem standard deboning time in the industry. Although deboning time can often be decreased, it is still necessary to wait until rigor mortis is complete to insure

Inspection is done at this point because the inspector can see all parts at the same time. The attached or detached viscera can reveal diseases or problems within the internal organs. Inspection requirements differ among countries, but inspection is usually carried out by a government official. This process is essential in insuring that only wholesome birds, free of

Slaughter-Line Operation | Poultry disease, reach the market place. In some countries, it is required that each individual bird be inspected by a qualified veterinarian; in other countries, inspection is done on a wholeflock basis and only certain carcasses are inspected by a trained inspector. The suspected birds receive a more thorough inspection and all or parts can be salvaged. In large-scale plants, the viscera are pulled out of the bird using a pack puller that places a clamping device into the abdominal cavity to pull the viscera and esophagus out of the abdominal cavity. Multiple inspectors (two to four) are often on the line to make sure that every carcass is inspected.

Giblet Salvage The viscera are removed after inspection and giblets (the liver, heart, and gizzard) are salvaged and washed on a separate line. The gizzard (stomach used to grind the food, as birds have no teeth) is first cut open, the contents are removed, and the lining is peeled off. Mechanical equipment used for peeling consists of two rollers that ‘catch’ the lining and pull it away; this is followed by washing and chilling. The hearts and livers are collected, inspected, washed, and chilled. The chilled giblets can then be collected and sold separately to reduce the risk of Salmonella and Campylobacter cross contamination.

Lung, Head, and Crop Removal The crop is removed by placing a spinning probe with barbs through the abdominal opening to push the crop through the opening where the head used to be. The probe is then cleaned and the crop is removed before retracting through the carcass. The lungs can be removed through the use of a vacuum gun that is inserted into the thoracic cavity and suctions the lungs from the dorsal surface of the rib cage. A neck breaker and neck puller is then used to cut the neck at the weakest point between the atlas and the axis vertebrae and separate it from the carcass. The neck is often included as part of the giblets, with the heart, gizzard, and liver.

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Inside/Outside Bird Wash Before entering the chiller, carcasses are washed to remove any material that is present inside and outside of the carcasses. The device usually consists of multiple spray nozzles positioned to cover critical areas in removing debris or blood clots both inside and outside of carcasses. Tilting the carcasses can assist in thorough draining of the water through both the abdominal opening (created during evisceration) and neck opening (formed after pulling the windpipe and the crop). Some designs have spray heads positioned along the moving shackle line, washing first the upper part of the carcasses and subsequently the lower part. Bactericidal rinses, such as chlorine and organic acids, can be used. Chlorine is one of the most commonly used chemicals (where permitted) and is typically used at up to 50 ppm in the rinse. Citric, lactic, and acetic acids have all been used at concentrations of 1.0% or less. Propionic acid, peroxyacetic acid (PAA), chlorine dioxide, and cetylpyridinium chloride (CPC) can also be used in spray washes, as dips or in the chiller to inhibit microbial growth. The washing operation is critical in reducing the number of microorganisms on the carcass and decreasing the incidence of pathogenic bacteria, specifically Salmonella and Campylobacter.

Chilling After the washing step, which occurs approximately 15 min after bleeding, the meat is placed in a chiller. The most common methods include water-immersion chilling, air chilling, and spray chilling. For immersion chilling, the carcasses are dumped into a trough-like structure, which usually contains either a large-diameter auger or paddles that move the birds forward (Figure 4). The most common design used today is the counterflow design, in which the product moves counter to the flow of the cold, clean water. This is a more efficient way of cooling the carcasses (the coldest temperature is at the end of the tank), which also assists in improving the hygienic conditions. The microbial quality of birds coming out of a water chiller is often better than before chilling because the water helps to wash off bacteria.

Figure 4 Auger carcass chiller (Left); side view of auger carcass chiller (Center); cross-sectional top view of auger carcass chiller.

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A prechiller (7–12 °C) is commonly used in a waterimmersion chiller for 10–15 min so that the carcasses have a gradual temperature transition. This is important because the lipids in the skin are liquid when the carcass enters the prechiller. The carcass temperature is generally approximately 30 °C after prechilling, when it enters the main chiller that has a water temperature of approximately 4 °C at the entrance and 1 °C at the exit. This counterflow design is designed to lower carcass temperature to 4 °C within approximately 2 h as well as maximize the heat transfer in the chiller. One problem that can occur in the chiller is thermal layering at the product surface that prevents carcass cooling. Injecting air or using water jets to pump water into chillers at high velocity prevents thermal layering. Chlorine, citric acid, lactic acid, acetic acid, propionic acid, PAA, chlorine dioxide, and CPC all either have been used or have potential for use in chiller systems through either direct addition or use in the pump water. Antimicrobials used in pump water are able to improve contact between the carcasses and the antimicrobials. In addition, a finishing chiller is used, where the carcasses receive a final rinse and antimicrobials to reduce the incidence of Campylobacter and Salmonella. Air chillers are commonly used in Europe and are starting to appear in North America and elsewhere. Cold air is used as chilling medium, so care should be taken not to dry the product surface and lose weight. This can be achieved by raising the air humidity or wetting the product at some point (s) along the line; this can reduce weight losses to approximately 1%. A typical setup includes an overhead rail that goes back and forth along a chilling tunnel or room. Depending on the tunnel capacity and the volume of product, chilling can be achieved within 60–150 min. Air chilling generally takes longer than water-immersion chilling because it is less efficient at heat exchange. The air-chilled carcasses are generally exposed to colder temperatures at the beginning of the chiller (−6 to −8 °C) and approximately 1 °C at the end of the chiller. Spray chilling is a hybrid between water and air chilling. Cold water is constantly sprayed over the carcasses while they are moved along the line. Moisture pickup is less during water chilling but higher during air chilling.

Grading, Weighing, and Packaging Grading is usually not mandatory, but it is done in most large markets to facilitate sales. The grade is based on the relative muscling, bone conformation, presence/absence of tears/ bruises/pinfeathers, and missing parts. Each country has its own specifications, but a bird (chicken, turkey, and duck) with adequate muscle deposition and no esthetic defects will generally be classified as Grade A; minor defects will result in Grade B; and more serious defects will result in Grade C. The last two categories will usually not be sold as whole birds but rather as parts (no grade labeling required) or as furtherprocessed products. Grading can be done by a qualified person or with the assistance of a computerized machine-vision system. The final overall grade can be affected by different processing parameters (e.g., stunning and chilling) as well as

feeding, growing, and transporting parameters described in other articles. Weighing of the ready-to-sell birds is usually done by automated weighing equipment connected to a computer network. Alternately, birds/parts can be packaged in bulk and sold to consumers interested in buying only certain parts (wings/drum sticks) or institutions/fast food restaurants interested in large quantities, depending on market demands.

See also: Hazard Analysis Critical Control Point and SelfRegulation. Microbiological Safety of Meat: Salmonella spp.; Thermotolerant Campylobacter. Spoilage, Factors Affecting: Microbiological

Further Reading Barbut, S., 2002. Poultry Products Processing − An Industry Guide. New York: CRC Press. Bilgili, S.F., 1992. Electrical stunning of broilers − Basic concepts and carcass quality implications: A Review. Journal of Applied Poultry Research 1, 135–146. Bilgili, S.F., 1999. Recent advances in electrical stunning. Poultry Science 78, 282–286. European Food Safety Authority Journal (EFSA), 2005. Opinion of the Scientific Panel on Animal Health and Welfare (AHAW) on a request from the Commission related to welfare aspects of the main systems of stunning and killing the main commercial species of animals. EFSA Journal 45, 1–29. Fletcher, D.L., 1999. Slaughter technology. Poultry Science 78, 277–281. Gregory, N.G., Wilkins, L.J., 1989. Effect of stunning current on carcass quality in chickens. Veterinary Record 124, 530–532. Guyton, A.C., Hall, J.E., 2010. Textbook of Medical Physiology, twelfth ed. Philadelphia, PA: Saunders Elsevier. (Chapter 43), pp. 527−533. Hoen, T., Lankhaar, J., 1999. Controlled atmosphere stunning of poultry. Poultry Science 78, 287–289. Kranen, R.W., Lambooj, E., Veerkamp, C.H., Van Kuppevelt, T.H., Veerkamp, J.H., 2000. Hemorrhages in muscles of broiler chickens. World's Poultry Science Journal 56, 93–126. Raj, A.B.M., Grey, T.C., Audsely, A.R., Gregory, N.G., 1990. Effect of electrical and gaseous stunning on the carcass and meat quality of broilers. British Poultry Science 31, 725–733. Raj, A.B.M., Johnson, S.P., 1997. Effect of the method of killing, interval between killing and neck cutting, and blood vessels cut on blood loss in broilers. British Poultry Science 38, 190–194. Raj, A.B.M., Wilkins, L.J., Richardson, R.I., Johnson, S.P., Wotton, S.B., 1997. Carcass and meat quality in broilers either killed with a gas mixture or stunned with an electric current under commercial processing conditions. British Poultry Science 38, 169–174. Raj, A.B.M., Wotton, S.B., McKinstry, J.L., Hillenbrand, S.J.W., Pierterse, C., 1998. Changes in the somatosensory evoked potentials and spontaneous electroencephalogram of broiler chickens during exposure to gas mixtures. British Poultry Science 39, 686–695. Sams, A.R., McKee, S.R., 2010. First processing: Slaughter through chilling. In: Owens, C.M., Alvarado, C.Z., Sams, A.R. (Eds.), Poultry Processing, second ed. Boca Raton, FL: CRC Press, pp. 25–49. Sams, A.R., Owens, C.M., 2010. Second processing: Parts, deboning, and portion control. In: Owens, C.M., Alvarado, C.Z., Sams, A.R. (Eds.), Poultry Processing, second ed. Boca Raton, FL: CRC Press, pp. 51–65.

Relevant Website http://www.efsa.europa.eu/en/efsajournal/pub/45.htm European Food Safety Authority.

Sheep and Goats CE Devine, The New Zealand Institute for Plant and Food Research, Hamilton, New Zealand KV Gilber, AgResearch Limited, Hamilton, New Zealand r 2014 Elsevier Ltd. All rights reserved. This article is a revision of the previous edition article by CE Devine, KV Gilbert, volume 3, pp 1250–1255, © 2004 Elsevier Ltd.

Glossary Bleeding/exsanguinations The procedure where the carotid arteries, jugular veins, and esophagus are severed − sometimes a knife is inserted to the heart, cutting additional vessels. Cardiac arrest Cessation of normal circulation. In this case, the passage of an electrical current through the heart causes fibrillation. Electrical stimulation Application of an electric current through a carcass postmortem that accelerates rigor mortis and enhances tenderization. Electrical stunning The procedure where a current is passed through the head of the animal, causing a seizure that ensures that the animal is insensible. If only the head is in the electrical pathway, the heart continues to beat and the animal can recover (head-only electrical stunning). If the body of the animal is in the pathway, the heart stops (cardiac arrest) and the animal cannot recover (head-tobody stunning). Evisceration Removal of the components of the body cavity, such as the heart, lungs, rumen, and the intestines. GR Thickness of the fat based on measurement of total tissue depth over the 12th rib at a point 11 cm from the midline.

Introduction There were approximately 861 million goats and 1078 million sheep in the world in 2008 with most (805 million goats and 739 million sheep) being in Asia and Africa and, additionally, 247 million sheep and 19 million goats in Europe and Oceania, the remainder being mainly in North and Central America and the Caribbean. This means that traditional nonmechanized methods of harvest predominate over mechanized systems. For sheep and goats, the small size means that they have been harvested and eaten by societies ranging from nomadic tribesmen to most western cultures for thousands of years. Not only do they provide meat but also hides and wool (sheep) are important by-products. The small size of sheep and goats are clearly advantageous, when they are slaughtered by individuals away from plants on farms or the steppes of Eurasia, but in commercial processes, the labor and mechanization required per carcass is disproportionately high compared with larger cattle and pigs. The labor required to produce a given weight of dressed carcass is generally less when the carcasses are large. Sheep are relatively small and traditional dressing methods with low levels of mechanization require approximately 80 man-hours per 10 000 kg of carcass.

Encyclopedia of Meat Sciences, Volume 3

Halal slaughter A slaughter procedure that adheres to Islamic teachings where the animal is dispatched by severing the blood vessels of the neck while the animal is facing Mecca. The knife cut can be preceded by a head-only electrical stun, provided it does not kill the animal and the animal is able to recover if not slaughtered. Harvest The whole process of production and processing animals. Inverted dressing A system where the carcass is suspended by the front legs in contrast to systems where the carcass is suspended by the hind legs. Pelt removal Removing the skin/hide from the carcass – also called depelting. Slaughter The process of bleeding/exsanguination where the carotid arteries, jugular veins, and esophagus are severed − sometimes a knife is inserted to the heart, cutting additional vessels. The blood loss ensures that the animal cannot recover sensibility. Stunning The procedure where an animal is rendered insensible before exsanguination, pelt removal, and evisceration.

Beef and poultry in contrast require only approximately 22 man-hours to produce the same weight, due to the large carcasses of the former and highly mechanized processing procedures for the latter. Procedures for sheep, the main species in commercial abattoirs, have changed rapidly and procedures for goats are adapted from those used for sheep. The main differences between sheep and goat harvest methods relate to the need to recover wool in sheep − the leanness and the generally lighter weight of goats mean that with rapid chilling, cold shortening and toughening are more likely to occur unless electrical stimulation is used. This article covers the mechanized processes that dominate in Oceania, North and South America, and Europe. Over the past 20 years, because of the large numbers exported, the New Zealand meat industry in particular has invested heavily in developing slaughter and dressing technology for sheep and lambs to reduce labor costs, to maintain stringent hygiene, and to improve the quality of the pelt and meat quality through all aspects of processing, including boning, cutting, packaging, and retail distribution. The industry in this country is one of the leaders in the field, and the situation is reflected in many other countries with minor changes in details.

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Traditional slaughter methods involve a severing of the throat, effectively cutting the carotid arteries, jugular veins, trachea, esophagus (weasand), and various nerves. The animals are usually hung up by their hind legs and then allowed to go through postmortem movements and to bleed out over a period of 5 min or more before depelting and viscera removal. Such slaughter procedures without stunning have been shown to be humane for sheep, where unconsciousness will occur 6–10 s post the knife cut. In many parts of the world where sheep are slaughtered in this manner, the procedures are also in line with those required for halal and kosher slaughter. A throat cut has been the main sheep and goat slaughter method throughout human history. When commercial processing operations with high throughputs are required, the sheep need to be transported to the facilities and lairaged before slaughter. Such procedures potentially involve varying degrees of preslaughter stress and consequent meat quality deterioration, so handling procedures to reduce stress should be implemented (including familiarization of animals to some stressors). In most countries of the world, sheep dressing takes place with dry wool surfaces, and the potential risk of contamination by dust, dirt, and fecal contamination does not appear to be a problem. In New Zealand, sheep have been vigorously washed by swimming through a race or have high-velocity water jets spraying the animals to remove visible dirt and feces, but it is unclear whether bacterial loads are reduced overall, because the moist conditions on the warm skin surface during drying would encourage bacterial growth. The stresses imposed can affect meat quality, and the process is being phased out. Goats do not need to be washed.

Stunning In commercial operations, preslaughter stunning is generally used, and the most common commercial method is electrical stunning. This is achieved by placing tongs spanning the head and passing an electrical current through the brain. With goats some care is needed in placing the electrodes behind the horns. This type of stun, termed a ‘head-only’ stun, does not stop the heart and the animal can potentially recover. As the slaughterman cuts the throat before the animal recovers, they are effectively taking the life of the animal and this procedure is, therefore, consistent with halal slaughter. Other stunning and slaughter procedures use a modification of the tong system with a pistol grip-like handpiece, which sometimes may be used for head-to-back (or body) stun and cause cardiac arrest (Figure 1). Cardiac arrest arises when a current passes through the heart but because the spinal cord is in the pathway, it additionally reduces the animal's reflexes with significant movement reduction, making it a good option when halal slaughter is not required. Ideally, the animals are presented to the stunner in a Vrestrainer (Figure 1). Additional advantages of the V-restrainer are that it allows precise location of the head of the animal and therefore facilitates automation of application of stunning. Such automated procedures not only reduce costs but also improve worker safety. One system has a series of grids that contact each side of the head. Nozzle electrodes, arranged throughout each

Figure 1 A slaughterman applying a head-to-back stun to a sheep in a restraining conveyor. Inset: A stun gun showing the pointed front electrodes that are applied to the head and the flat rear electrode through which water is also applied to the wool to lower electrical resistance.

grid, then apply an electrical current to the head, concurrently with water to facilitate current flow. Most countries require preslaughter stunning before slaughter. Head-only electrical stunning is consistent with halal, but it is not acceptable for kosher slaughter.

Bleeding Once the animals are stunned, the throat is cut, and bleeding takes place either by a traditional gash cut as mentioned above or by a thoracic stick that severs the atria and vessels leading to the heart. In some plants, the animals are suspended by hooks on the rail system before they are bled (Figure 2). The blood leaving the carcass is not affected by the stunning procedures. If the heart is still beating, the animal initially bleeds by blood being pumped via the heart from the carotid arteries. At the same time, blood drains into the heart from the jugular–vena cava system. As the heart refills from the venous system draining into it, the amount of blood being lost by cardiac action reduces when the heart cannot fill due to the cut vessels. Eventually, a stage is reached when all the remaining blood must drain by passive means from the severed vessels. With electrical stunning, and in particular head-to-body stunning, there are other types of sticking, for example, a thoracic stick draining blood rapidly via the venous system so that this becomes the main mechanism of bleeding rather than via the carotid artery. It is important to note that from the moment the atrium/vena cava or heart is pierced, bleeding takes place passively (helped by gravity) – this is true for animals shot in the head with a captive bolt as well as electrically stunned animals. Cardiac arrest, therefore, has little or no effect on overall blood loss (providing vessels are severed before clotting occurs). To prevent contamination by ingesta, the weasand (throat or esophagus) is tied or clipped. Support of the hind legs facilitates good bleeding. However, with increased efficiency on the dressing line, time delays

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for example, a head-to-back electrical stun where there is effectively a shearing action between the fat and muscle fascia initiated by muscle contraction.

Pelt Removal

Figure 2 Two sheep carcasses on a processing line. One rear leg is tightly held and the front legs are on a spreader. The nearest animal has just been stunned and not yet bled. The second has just finished bleeding, and knife workup on the neck and fore legs has just commenced. This allows the commencement of head workup and separation of the skin from the brisket area and precedes pelt removal.

are not desired and some procedures are telescoped. For example, carcasses are suspended by both the two rear legs and front legs soon after slaughter commences. This can result in blood pooling in the thoracic area before it bleeds out, if the thorax is lower than fore and hind legs (the correct angle is shown in Figure 2). Clotting occurs because blood that remains in the large vessels, such as the jugular and the vena cava, retains all clotting factors – it, therefore, needs to be rapidly removed. An interesting situation occurs in small vessels (such as those supplying and draining the pelt) where blood leaks out from cut surfaces. This occurs because the biochemical factors that facilitate clotting rapidly diffuse away through the thin vessel walls, so clotting is reduced. Sometimes there are cosmetic deficiencies with poor bleeding. One type, termed blood splash, results when blood from vessels, torn through muscle spasms (usually, but not always, from an electrical stun), are retained in the muscle. Another cosmetic deficiency, termed speckle bruising, appears as myriads of small red spots lying in the fat over the loin to give a ‘salt and pepper effect,’ which may coalesce in extreme cases producing a fiery red effect. The defect is particularly visible in sheep, but it can be found in goats, cattle, pigs, and even deer – it is only when it is severe that it is a problem. This defect, essentially the beginning of a bruise, is generally caused by a violent movement just before or during slaughter,

Traditionally, sheep were depelted while hanging from their hind legs, and this provided the basis for early mechanized systems with various gambrels or hooks placed through the Achilles tendon. By careful knife work, the areas around the rump are cleared, then the legs and the thorax are cleared, and finally the pelt is pulled over the body and head. At all stages, it is desirable to keep the carcass clean; paper is often placed at judicious places to prevent the pelt rolling inward and contaminating the carcass – this is more important for sheep than goats. In the late 1970s, the benefit of depelting the sheep and goats from the shoulder to the hind leg was recognized, and this process was most easily achieved by suspending the animal by front legs. This process, known as the ‘inverted’ system, formed the basis of many subsequent developments to date with considerable manpower reductions over previous systems. Because the hind legs are at the lowest point, it has the added benefit of reducing fecal contamination and maximizing the return from every part of the carcass, including offal. One of its major attributes is its simplicity and ease of installation as many of the tasks and skills used in the inverted system were used in previous systems. The inverted manual system requires a mechanical puller to remove the pelt from the rear and then over the front legs. Many variations have been tried in New Zealand and at present at least 10 different designs are being used in meat plants for both sheep and goats. Most of the designs can process at least eight carcasses per min. In one system, the pelt is manually removed around the brisket, cleared from the back area, and the hanging pelt is placed between prongs of the puller shown in Figure 3. The prongs rotate (Figure 4) and trap the pelt, and then the device moves down the carcass, removing the pelt. Automatic front and rear hock removal machines have also been produced, and machines to assist the transfer of the fore legs from the wide spreader to the narrow hock holder have been developed. Potential contamination from the front trotters onto the carcass is eliminated during the major part of the pelting operation.

Evisceration After depelting, evisceration and offal handling, such as removal of the intestines, liver, lungs, and heart, are the next biggest users of manpower. Several developments have been undertaken to partly mechanize this area. Brisket cutting and belly opening was the first area studied. A machine not only cuts the brisket but also opens up the belly area. Further developments facilitate viscera removal.

Head Processing The focus of developments in head skinning and brain and tongue removal has changed, as the European Union (EU)

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Figure 3 The four prongs are part of a system to remove the pelt from a sheep carcass. The pelt is freed from much of the carcass, and a hanging portion is placed between the prongs, which can rotate.

regulations regarding head inspection required that a totally skinned head had to be presented with the carcass for carcass inspection. A number of head-skinning machines were developed. In one type, a small shaft gripped a flap of skin near the nose and removed the remainder of the skin by a rolling action. The regulation requiring heads to be presented with the carcass was partially relaxed in 1987, so that only those heads from which edible brains and tongues were to be used for human consumption needed to be inspected. Edible brains can still be obtained from sheep in countries without bovine spongiform encephalopathy or scrapie. Small incremental developments include automatic atlas joint severing, automatic head splitting, and automatic brain extraction.

Mechanization Traditionally, mechanization has focused on direct task replacement. Inverted dressing offered significant advantages in this respect and has generated significant benefits over the past 20 years. With reducing numbers and increased focus on adding value through further processing, the current focus has moved toward more advanced automation and robotics. With the incremental development of mechanized devices, the output from a mechanized sheep dressing system, processing 8 lambs per min, requires 25 butchers plus 11 assistants, the actual labor requirements highly depending on throughput, in

Figure 4 The rotating prongs grip the pelt and pull it down over the rear legs in this inverted dressing system.

contrast with the older systems that needed 44 plus 15 assistants. The recently developed robotic brisket cutting and evisceration robots, combined with a new evisceration inspection protocol, have the potential to remove five evisceration inspection and sorting labor units on a typical eight lambs per min chain. The best-mechanized system is likely to produce carcasses and pelts of a quality equal to or better than any economically viable manual system of a similar throughput. The cost benefit of mechanization has to consider processing quality. Poor hide pulling that impacted on fat over the ribs would have zero impact on value because the fat cap is removed when cutting into French racks; however, an evisceration robot that damaged 1% of runners could be significant. Modern pelt-pulling equipment senses the force required in removing the pelt. Additional labor units are often deployed to do the necessary workup to ensure product quality as these extra labor units are often doing other part tasks as well; therefore, the combination of mechanization and labor deployment must stack up financially. However, the alternative of a fully manual operation is not viable these days due to throughput requirements and health and safety issues.

Sheep and Lamb Carcass Grading There is no international carcass grading system for sheep, lambs, and goats, but some generalizations can be made, and

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in particular, sex and age are important. Mutton is a female (ewe) or an adult noncastrated male (ram) or a castrated male (wether) with more than two permanent incisors in wear. A hogget is a young male sheep or a maiden ewe having no more than two permanent incisors in wear. Lambs are young sheep less than 12 months of age and without any permanent incisors in wear. New Zealand, Australia, and the EU account for almost 90% of lamb exports, but each country is serving specific markets and therefore the systems are not the same. The greatest sheep meat production is in China, followed by the EU, Australia, New Zealand, and the Middle Eastern countries (where goats are processed as well), all with different grading systems. Links to the various systems can be obtained from web links cited in further reading. VIASCAN systems (video analysis) based on carcass conformation are now being used. In many systems, grading is based on the overall size and conformation and the fat cover. In New Zealand, the thickness of the fat based on measurement of total tissue depth over the 12th rib at a point 11 cm from the midline, called GR, is used (the fat cover on the longissimus muscle is not such a useful guide as in pigs). The export grades are based on three grades of leanness (A ¼ devoid of external fat, Y ¼ low fat, and P ¼ medium fat). Excessive fat is trimmed and gives rise to another series of grades. There are then, superimposed on this, four weight grades (L ¼ 9–12.5 kg, M¼ 13–16 kg, X ¼ 16.5– 20 kg, and H¼ 20.5 kg and more). Australia follows a similar, but not identical, system.

Electrical Stimulation, Chilling, and Freezing Once the pelt and the viscera have been removed from the carcasses, they can be graded and weighed, and they move down the chain to an area where they may be electrically stimulated. There can be either a low- or a mid-voltage system applied early postmortem (Figure 5) or a high-voltage system at the end of processing (Figure 6). It is ideal for meat to reach temperatures approximately 15 °C at rigor mortis (412-h postmortem without stimulation) to avoid cold shortening and ensure optimum aging. Compared with beef, the small carcass size of sheep and goats means that excessive rates of chilling or freezing can easily occur with the risk of cold shortening and toughening when temperatures are significantly lower than this. As electrical simulation considerably reduces the time to rigor mortis (3–5-h postmortem, depending on type of stimulation), cold shortening is unlikely to occur. In New Zealand, the accelerated conditioning and aging (AC&A) process was developed and resulted in sheep with a known tenderness specification. The AC&A process consists of high-voltage electrical stimulation using 1130 V peak, 2 A peak, 15.5 sine wave pulses per s for 90 s, which passes from the middle of the back through the legs of many carcasses as they move slowly along the electrode system (Figure 6). Alternative systems utilize a low-voltage system current (80 V peak, 120–300 mA peak, 15 pulses per second) before depelting or a mid-voltage system after depelting (300 V peak 5 ms duration square wave pulses at 15 pulses per s). Chilling or freezing processes together with prior procedures, such as electrical stimulation, have an

Figure 5 A low-voltage stimulation unit for sheep that can be used in processing plants with a small throughput. The current (80 V peak, 120–300 mA peak, 15 pulses per s) passes from the front legs to the earthed rail. The duration of stimulation ranges from 30 to 60 s. In this system, the stimulation is applied at the end of dressing but earlier stimulation at the end of stunning may be used and this has the advantage that carcass movement poststun is reduced. Three sheep are connected at a time in this system. The carcasses with the current flowing have the front legs outstretched.

interdependent effect on optimal processing and on product quality, so a single set of process cannot be put in place. In a typical procedure, the carcasses are aged (tenderized) at air temperatures above 6 °C for 8–12 h before being frozen or packaged for chilled distribution. Sheep carcasses can be further processed into cuts and packaged for distribution. With the best processing hygiene and the use of either vacuum packaging or controlled atmosphere packaging systems, chilled rather than frozen meat can be distributed worldwide for retail distribution for as long as 10–12 weeks postmortem at −1.5 °C.

Future Trends To date, sheep dressing is based fairly heavily on mechanical principles. In the future, however, rapid developments in the areas of electronic sensing, vision, and robotics are expected to affect carcass dressing. Initially, these new developments will be used to control existing machinery for greater processing accuracy. For significant further manpower reductions in sheep

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See also: Automation in the Meat Industry: Cutting and Boning. Conversion of Muscle to Meat: Aging; Rigor Mortis, Cold, and Rigor Shortening. Electrical Stimulation. Meat Marketing: Cold Chain. Microbiological Safety of Meat: Prions; Viruses. Preslaughter Handling: Preslaughter Handling. Refrigeration and Freezing Technology: Freezing and Product Quality. Religious Slaughter. Stunning: Electrical Stunning

Further Reading Aziz, M.A., 2010. Present status of the world goat populations and their productivity. Lohman Information 45, 42–52. Available at: http://www.lohmann-information. com/content/l_i_45_artikel17.pdf (accessed 26.04.14). Barton-Gade, P.A., Chrystall, B.B., Kirton, A.H., et al., 1988. Slaughter procedures for pigs, sheep, cattle, and poultry. In: Cross, H.R., Overby, A.J. (Eds.), World Animal Science, Meat Science, Milk Science and Technology, vol. B3. London: Elsevier Science Publishers, pp. 33–111.

Figure 6 A typical high-voltage electrical stimulation system for lambs in a meat processing plant. The current (1100 V peak, 2 A peak, 15 pulses per s) passes from the middle of the back through the legs of many carcasses as they move slowly along the electrode system, taking 90 s to complete the process. Reproduced with permission of AgResearch Limited, New Zealand.

and lamb, and even goat, processing, tasks such as opening cuts and clearing cuts, would have to use robotic technologies. To date, the best set of improvements has reduced the labor required for a traditional system by more than 40%, so instead of earlier requiring more than 2.6 times as many man-hours to produce the same weight of carcass as a chicken processing system, it now requires only 1.3 times as many.

Relevant Websites http://www.ausmeat.com.au/industry-standards/specification/lamb.aspx AUS-MEAT Limited. http://www.beeflambnz.com/market/meat-specifications-and-processing/ Beef and lamb New Zealand. http://www.grandin.com/index.html Dr. Temple Grandin's Web Page. http://www.dartmoor-npa.gov.uk/__data/assets/pdf_file/0014/42008/li-dhfpsheep.pdf Meat South West.

SMOKING

Contents Liquid Smoke (Smoke Condensate) Application Traditional

Liquid Smoke (Smoke Condensate) Application J Rozum, Red Arrow Products Company LLC, Manitowoc, WI, USA r 2014 Elsevier Ltd. All rights reserved. This article is a revision of the previous edition article by A Borys, volume 3, pp 1272–1277, © 2004 Elsevier Ltd.

Glossary Carbonyls A class of compounds responsible for the browning reaction contained in smoke. Condensable and noncondensable gases Condensable gases are those that form a liquid at room temperature; noncondensable gases do not. Condensed smoke Cooled gaseous smoke. Genotoxic Agents known to damage DNA. Liquid smoke preparations These are combinations of condensed smokes.

Introduction Liquid smoke preparations are used extensively in meat processing. The application of liquid smoke (smoke condensates) is steadily displacing the use of traditional smoking. Research conducted in the 1960s and 1970s provided information about the basic aspects of the smoke-generating process and traditional smoking. The work dealt with the thermal degradation of wood, the physical and chemical properties of woodsmoke, the phenomena occurring in the smoking chamber, the diffusion of the smoke components into the products being smoked, and the bactericidal and antioxidative properties of woodsmoke. Studies were aimed at determining the chemical composition of woodsmoke condensate and the mechanisms in the production of polycyclic aromatic hydrocarbons (PAHs); the role of nitrogen oxides generated during thermal degradation of wood was also investigated. Many articles dealt with the species and moisture content of the wood, the degree of disintegration (wood chips or sawdust), and the sensory properties of the smoke preparations or of the smoked products. Attempts were also made to determine the relationship between the chemical composition of the smoke preparation and its sensory properties. The results of these studies were used in the development of the first generation of liquid smoke preparations. Usually

Encyclopedia of Meat Sciences, Volume 3

Polycyclic aromatic hydrocarbons (PAHs) These are the cancer-causing agents. Rapid thermal pyrolysis A pyrolysis method taking less than 1 s. Rotary oven A slow pyrolysis reactor; pyrolysis occurs more than 1 min. Tar fraction The non water-soluble fraction of pyrolysis that is removed from smoke. Water fraction The gaseous phase of smoke that is condensed in water.

these preparations did not have the required stability and reproducibility from batch to batch. Many preparations produced at that time contained considerable quantities of PAHs. By the mid-1970s, progress in the manufacturing technology had largely eliminated the problems with smoke condensates. The smoke condensates made today are characterized by a high and repeatable quality level. The great increase in the application of smoke condensates is based on numerous factors: the development of new technological methods for producing smoke condensates; the development of technical solutions for application of the smoke condensates; environmental restrictions on the use of traditional smoke; and requirements for health and safety at work.

Methods for Smoke Condensate Production The predominant raw material for production of smoke condensate is wood, typically of one or more of the following tree types: beech, oak, hickory, maple, eucalyptus, ash, apple, cherry, birch, mesquite, and pecan. Wood to be used for smoke condensate manufacture may be reduced to sawdust or chips, dried to approximately 5% moisture content and thermally decomposed. In some processes batch retorts are still in use. The thermal decomposition of the wood is carried out

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under controlled conditions. Usually the process is a slow pyrolysis performed in externally heated retorts or in rotary ovens. In recent years, a so-called rapid thermal pyrolysis has been introduced. This enables the process of wood decomposition to be carried out in less than 1 s. The sawdust is introduced into a reactor in which heated sand is being circulated. When the hot sand comes in contact with the sawdust particle, the sawdust is pyrolyzed, forming the smoke components. The smoke is quickly transferred to a recirculation column where it is condensed. This ensures that a larger portion of the carbonyls is retained, forming a higher-browning capability smoke. Of primary importance in the pyrolysis process is the temperature of wood decomposition. The temperature of decomposition has a fundamental influence on the quantity of condensate and its chemical composition. Most often the temperature is between 450 and 500 °C. The use of lower temperatures for wood decomposition considerably increases the content of carbonyl compounds and tar in the smoke condensate. The temperature depends on the reaction method used and which fraction is more desirable to the producer. The condensable and noncondensable gases created during the thermal decomposition of wood are contacted with a recirculating water phase of smoke condensate. Noncondensable gaseous components of wood pyrolysis contain carbon monoxide, methane, and hydrogen, resulting in a flammable gas stream that may be burned to generate heat utilized in further manufacturing steps. After cooling, concentration, and normalization, the smoke condensate is separated into a water fraction and a tar fraction. For manufacture of commercial condensed smoke preparations, both fractions may be used individually, although the tar fraction must be further processed to remove the high levels of genotoxic polycyclic aromatic hydrocarbons. The water fraction is subjected to storage for some time to isolate the slowly precipitating fraction of tar that continues to form at decreasing rates over the lifecycle of the condensate. Before further processing, the water fraction is subjected to multiple filtration steps to purify the liquid. The water fraction may then be concentrated by distillation or extraction. To improve its stability when stored, emulsifiers, such as Polysorbate 80, are added. The filtered water fraction of smoke condensate, while useful in its native form, is best suited as an intermediate product to be used in the manufacture of many commercial forms of condensed smoke preparations. Each manufacturing batch is examined for its content of basic components. Usually, determinations of total organics content, acids (expressed as acetic acid), phenols, and carbonyls are carried out. For the preparations used for coloring of food products, methods that assess the reaction of the condensed smoke product with glycine are usually employed to determine the Maillard reaction potential of the condensed smoke. Commercial condensed smoke preparations are normally offered in the following forms: • Concentrated liquids for atomizing, or smoke regeneration, into smoking/cooking chambers, which is done nearly exclusively in batch processes. • Extracts to be incorporated into food products by injection or mixing.

• Water-miscible solutions for showering products in batch and continuous processes. • Powder on carriers such as maltodextrin, salt, yeasts, flours, spices, and seasonings to provide smoke flavor. High-strength liquid smoke preparations are obtained from the tar fraction by distillation and/or extraction. These are highly enriched phenolic products that have far smaller amounts of the water, acids, and carbonyls that are present in seminal woodsmoke. Although smoke preparations of this type have use as is, typically they are more likely to be used commercially on carriers or in emulsions. These preparations possess only the smoke flavor without the coloring ability.

Chemical Composition of Liquid Smoke Preparations The chemical composition of condensed smoke preparations varies as much as the composition of natural smoke, but the condensed smoke preparations do not contain the gaseous components of traditional smoke. The chemical composition of condensed smoke depends on the raw material used, the method and conditions for wood decomposition, and the methods for purification, condensation, and stabilization. During pyrolysis, the cellulose and hemicelluloses contained in wood generate organic acids, aldehydes, aliphatic and cyclic ketones, furans and pyrans plus derivatives, lactones, aliphatic alcohols, and anhydrous sugars. From the 25% or so lignin fraction of wood, a full range of phenolic compounds is produced. Most of the phenolics fall into the general classes of guaiacols, syringols, dihydroxybenzenes, and methylated phenols. Condensed smoke preparations to be used for topical application contain the following key components: Water Acetic acid Formic acid Glycol aldehyde Formaldehyde Glyoxal Acetol Levoglucosan Water-insoluble tar

40–75% (w/w) 4–12% 0.5–3.5% 1.78–5% 0.5–1.2% up to 1.2% 2–5% 1.5–5.5% up to 7%

The preparations also contain several minor components, which are present at low levels (1.0 mg g−1 ¼ 0.1%). • Furans (furfural, furan, and derivatives): 2–8 mg g−1. • Phenols (phenol, cresols, dimethylophenols, and derivatives): 0.4–2 mg g−1. • Dihydroxybenzenes (catechol, hydrochinone, and derivatives): 2–7 mg g−1. • Guaiacols (guaiacol and derivatives): 1–7 mg g−1. • Syringols (syringol and derivatives): 0.8–10 mg g−1. • Aromatic aldehydes (vanillin, syringol aldehyde, and derivatives): 0.2–2 mg g−1. • Other components (cyclotene, maltol, aliphatic aldehydes and ketones, etc.): 3–25 mg g−1. In addition, some preparations contain several hundred components at levels of micrograms per gram.

Smoking | Liquid Smoke (Smoke Condensate) Application There is a wide variety of preparations of condensed smoke to be incorporated into food products. They can contain lower levels of the chemical compounds listed above because they are produced either by mixing the water fraction with carriers or extraction of certain components, or they may be converted into dry forms. The levels of phenolic compounds may vary by a factor of ten or more in the different preparations. The ratios between the different groups of compounds can also vary considerably. Products made from the tar fraction of the smoke condensate have different chemical compositions. These preparations contain much greater quantities of phenolic compounds with considerably lower levels of other constituents. The primary components of these condensed smoke preparations from the tar fraction are syringol, 4-methylsyringol, 4-isopropenylsyringol, 4-ethylsyringol, isoeugenol, eugenol, guiacol, 4-methylguaiacol, phenol, and cresols. The total content of phenolic compounds may be a third of the mass. The PAH content in condensed smoke preparations depends primarily on the production method and degree of purification. Preparations manufactured by smoldering wood might contain several hundred milligrams of PAHs per kilogram. The method of wood decomposition used today, which utilizes lower and precisely controlled temperatures, has made it possible to reduce the level of PAHs considerably from that of the past. Thirty-four PAHs have been identified in condensed smoke preparations, and are present in highly varying quantities. Naphthalene and its derivatives are present at the highest level. The total quantity may be as high as 1800 mg kg−1 with a total PAH content of 3195 mg kg−1. In Europe, regulation EC 2065/ 2003 limits benzo[a]pyrene to 10 mg kg−1 and benzo[a]anthracene to 20 mg kg−1 in smoke condensates that are used in foods. In the water phase of smoke condensates, the level of benzo[a]pyrene may be below 1 mg kg−1 when the tar component in the smoke condensate is below 1%.

Smoke Condensate Application Methods The manufacture of smoke condensates has made it possible to replace traditional smoking and has created new technological possibilities. The application of smoke condensates to meat products may be classified into three basic groups: smoke regeneration (atomization), drenching or showering, and internal addition. The first and second include methods for surface application; the third group covers incorporating the smoke into the products. Applying smoke condensates to the surface of products is most frequently done in normal smoke application chambers used for traditional smoking or in specially designed units. Numerous techniques are used for applying smoke condensates to products in smoke application chambers including pneumatic or hydraulic nozzles, thermal spraying, electrostatic deposition, and ultrasound or centrifugal atomizers to form a regenerated smoke cloud (Figure 1; Table 1). Color and flavor achieved are dependent on the smoke used, time smoked, meat block formulation, and processing

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Figure 1 Smoke application in a smoke chamber is carried out with low-velocity circulating air or air movement derived only from the application mechanism itself. The amount of smoke applied is controlled with metering pumps or by air pressure. Optimal smoke regeneration is obtained by sequential steps that include an atomization step followed by a circulation step while the dampers of the smoke house are closed. This also optimizes the use of the smoke. Multiple cycles of smoking and circulating may be utilized to provide the desired flavor and color (see Table 1 for an example of a frankfurter processing schedule with condensed smoke regeneration).

schedule. In general, any color from light tan to very dark brown and very light smoke to heavy smoke flavor can be obtained. The volume of smoke used depends on many factors. In most cases the quantity used for a manufacturing cycle is determined by the desired color intensity and flavor of the smoked product. A use of 1.5–3 kg of condensed smoke per ton of product is usually sufficient. Applying smoke condensates via smoke regeneration in smoking chambers provides a result very similar to a traditional smoking process (Figure 2; Table 2). The color intensity and the degree of smoke flavor can be controlled by the concentration of the smoke condensate and by the contact time between the smoke solution and the product. Another group of smoke condensates are designed for internal addition. This method is utilized to add flavor to the meat without affecting the color, and for adding a level of antimicrobial and antioxidant protection to meats. The level and type of smoke used are determined by the application method and flavor desired. To ensure a uniform distribution of this type of application in the product, smoke is normally applied in a bowl chopper or added to an injection marinade. Usage rates can be quite low depending on the smoke product used, but usually range from 0.05 to 1 g kg−1 of the meat product. The process of curing meat should not be combined with the addition of a high-acid smoke concentrate. Several smoke condensates, however, are available with higher pH and low acid levels that can be added to brines. The reason is that

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Table 1

Example of Frankfurter manufacturing process utilizing smoke regeneration

Chamber conditions

Time

Dry bulb temperature (°C)

Humidity

Reddening Drying Smoking

10 min 20 min 19 min 3 min smoking 4 min circulating 2 min smoking 4 min circulating 2 min smoking 4 min circulating 10 min

50 55 55

90% 0% 0%

60 78 75

0% 100% to core temperature of 71 °C 0%

Drying Cooking Dry

5 min

meat cuts to allow for even flavor distribution and better end product uniformity.

Use of Smoke Condensates

Figure 2 Showering or drenching the surface of the meat product or immersion in smoke condensate solutions is widely used. In drenching, a solution of the smoke condensate is showered over the product for a specific amount of time. Normal solution concentrations range from 5% to 50% smoke. The smoke condensate solution is recirculated through a filter system and back over the product to get the highest usage out of the condensate. The meat products are showered for 15–90 s to obtain the desired results (see Table 2 for an example of a showered frankfurter processing schedule).

Table 2

Example of a showered Frankfurter processing schedule

Chamber conditions

Time (min)

Dry bulb temperature (°C)

Humidity

Reddening Drying Drying Cooking

10 15 15

55 60 65 78

5

75

90% 0% 0% 100% to core temperature of 71 °C 0%

Dry

nitrites used in the curing process may react with the acid in smoke condensates forming nitrogen dioxide if a low-acid smoke is not used. Smoke condensates for brine addition allow for injection into bacon, ham, loins, and other larger

Generally, smoke condensates can completely replace traditional smoking. Their use is especially common in automated and highly productive manufacturing lines where smoke condensates are widely used for manufacture of popular smoked meat products produced in large quantities. They are especially useful in continuous manufacturing lines using special tunnels and a series of smoking chambers. For smaller-scale production units, equipment has been developed for showering the products with smoke condensates immediately after stuffing of the casings. Smoke condensates are also used in the coextrusion process, in which a collagen dough is extruded around the meat batter. This can provide flavor and structure to the sausage. The following advantages can be achieved by using smoke condensates instead of traditional smoking: • Eliminating the emission of harmful and undesirable chemical substances to the surrounding atmosphere. • Avoiding the fire risk associated with traditional smokehouses. • Reducing the processing time and weight loss of traditional smoking. • Reducing labor costs. • Increasing product throughput. • Reducing smoke chamber clean-up time and expense. • Producing a healthier finished product with little or no PAH. In the opinion of many consumers, use of smoke condensates in meat products, even at very low quantities, improves the flavor and aroma of the products. Although according to expert panels, smoke condensates do not usually achieve a smoke flavor identical to that achieved with traditional smoking, testing has shown that consumers do not have a preference for traditional flavor. Use of smoke condensates requires knowledge of their properties and experience and understanding of consumer preferences. The application of smoke condensates for meat products should be preceded by consultation with the smoke condensate manufacturers and

Smoking | Liquid Smoke (Smoke Condensate) Application technical tests in the manufacturing facility. Exceeding the optimal level for a given product can result in off-flavors in the treated product, most often in the form of an acid, sharp, acrid, chemical, or medicinal aftertaste.

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polyphenols in the preparations are active antioxidants and may provide some beneficial health effects.

Health Aspects Relating to the Use of Smoke Condensates Properties of Smoke Condensates Smoke condensates possess, like traditional smoke, coloring, bactericidal, and antioxidant properties. Aldehydes and aliphatic ketones are responsible for the coloring effect. The main aldehyde responsible for the coloring is hydroxyacetaldehyde. The aldehydes react with nitrogen in protein to begin the Maillard reaction. As the reaction progresses, it forms crosslinking of the proteins and color bodies. The color is then set or stabilized in the meat matrix by proper drying. Without proper drying, the color can fade or migrate, leaving a product that is much lighter in color than when first produced. Testing can determine the proper process to use to ensure that the color is properly set. Acetic acid lowers the pH value on the surface of the product. Acid is important for skin formation on sausages and providing the ‘tang’ in other meats. Acid level is also used quite extensively as an easy control measure for maintaining showering and drenching systems. Phenols are mainly responsible for the typical flavor of the smoked product. Even with the extensive knowledge about the composition of smoke condensates, it is still not possible to fully predict the quality of the smoke flavor. This places a certain amount of pressure on integrators to achieve the best possible outcome in a given situation. Among the phenolic compounds, syringol and its derivatives are the most desirable for creating a good smoke flavor. Other desirable compounds are guaiacol and its derivatives. Furfural and its derivatives, cyclotene, maltol, and aromatic ketones and aldehydes also play important roles in composing the overall smoke flavor. Smoke condensates also have bacteriostatic and bactericidal properties. The bactericidal activity is related to the concentration of the smoke condensate in the product. The minimum inhibitory concentration (MIC) has been determined for some smoke condensates. For Bacillus spp., Staphylococcus aureus, Listeria spp., Lactobacillus spp., Escherichia coli, Salmonella spp., Yersinia spp., and Pseudomonas spp., the MIC is 0.4% for the most active smoke condensates. For less active preparations, the MIC is 1–8%. Published studies indicate that the levels of phenolic compounds and acetic acid in liquid smoke preparations are most important for their bacteriostatic properties. Aldehyde compounds are also very good antibacterial agents in smoke, making all three main groups of smoke compounds important in antimicrobial effects. However, the great variation in the chemical composition of commercial smoke condensates means that their bacteriostatic properties can only be considered a support to the basic preservative concept for a given food product. The antioxidative property of smoke condensates is related to the content of phenolic compounds. The antioxidative activity of smoke is mainly controlled by the following compounds: cis–trans-4-propenylsyringol, 4-isopropenylsyringol, 4-propylsyringol, 4-ethylsyringol, 4-methylsyringol, syringol, and the 4-derivatives of guaiacol. It is also assumed that

Smoke condensates have been classified by the Food and Drug Administration (FAO) as generally recognized as safe (GRAS) in the US since 1980. In 1987 the FAO/World Health Organization Expert Committee on Food Additives set recommended maximum levels for a number of risk contaminants in smoke condensates including benzo[a]pyrene at 10 mg kg−1 and benzo[a]anthracene at 20 mg kg−1. Subsequently, the Council of Europe followed by the European Union took up the assessment of smoke condensates. As a result, the European Food Safety Authority (EFSA) evaluated dossiers and published opinions on a number of smoke condensates from both water-based and tar-based condensates. The EFSA concluded that there was no genotoxicity concern over the products presently on the market throughout Europe. At the time of writing the European Commission is determining whether limits are advisable on the use of these condensates based on applied safety factors derived from feeding studies. It is certain that smoke condensates do not contain nitrogen oxides and that the PAH level in the food products with smoke condensates is considerably lower than after traditional smoking. The amount of tar introduced into food products during the process is also much lower than with traditional smoking. In general, the use of smoke condensates allows a controlled application of the smoke organics necessary to achieve the color, flavor, and antioxidant and antimicrobial effects of smoke in smoked food products.

See also: Bacon Production: Bacon. Chemical Analysis for Specific Components: Curing Agents. Cooking of Meat: Maillard Reaction and Browning. Processing Equipment: Brine Injectors; Mixing and Cutting Equipment; Smoking and Cooking Equipment. Smoking: Traditional

Further Reading Baltes, W., Söchtig, I., 1979. Niedermolekulare Inhaltsstoffe von RaucharomaPräparaten. Zeitschrift für Lebensmittel-untersuchung and -Forschung 169, 9–16. Borys, A., 2001. The studies on the composition and properties of the selected liquid smoke used in Polish meat industy. Roczniki Instytutu Przemyslu Miesnego i Tluszczowego 38, 113–124. Borys, A., Platek, T., Wegrowski, J., 2000. An attempt to determine the relationship between chemical composition of wood smoke preparation and its antioxidative properties. Roczniki Instytutu Przemyslu Miesnego i Tluszczowego 37, 171–185. Council of Europe, 1998. Health Aspect of Using Smoke Flavours as Food Ingredients. Belgium: Council of Europe, Publishing and Documentation Service. ISBN: 92-871-2189-3. Estrada-Munoz, R., Boyle, E.A.E., Marsden, J.L., 1998. Liquid smoke effect on Escherichia coli O157:H7, and its antioxidant properties in beef products. Journal of Food Science 63, 150–153. Guillén, M.D., Ibargoitia, M.L., 1998. New components with potential antioxidant and organoleptic properties, detected for the first time in liquid smoke flavouring preparations. Journal of Agricultural and Food Chemistry 46, 1276–1285.

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Guillén, M.D., Manzanos, M.J., 1996. Study of the components of an aqueous smoke flavouring by means of Fourier transform infrared spectroscopy and gas chromatography with mass spectrometry and flame ionization detectors. Advances in Food Science 18, 121–127. Guillén, M.D., Manzanos, M.J., 1996. Study of the components of a solid smoke flavouring preparation. Food Chemistry 55, 251–257. Guillén, M.D., Sopelana, P., Partearroyo, M.A., 2000. Determination of polycyclic aromatic hydrocarbons in commercial liquid smoke flavourings of different compositions by gas chromatography−mass spectrometry. Journal of Agricultural and Food Chemistry 48, 126–131. Kim, K., Kurata, T., Fujimaki, M., 1974. Identification of flavor constituents in carbonyl, noncarbonyl neutral and basic fractions of aqueous smoke condensates. Agricultural and Biological Chemistry 38, 53–63. Kjällstrand, J., Petersson, G., 2001. Phenolic antioxidants in alder smoke during industrial meat curing. Food Chemistry 74, 85–89. Maga, J.A., 1988. Smoke in Food Processing. Boca Raton, FL: CRC Press.

Potthast, K., 1984. Liquid smoke, its use in the surface treatment of meat products. Fleischwirtschaft 64, 328–331. Suñen, E., 1998. Minimum inhibitory concentration of smoke wood extracts against spoilage and pathogenic microorganisms associated with foods. Letters in Applied Microbiology 27, 45–48. Suñen, E., Fernandez-Galian, B., Aristimuño, C., 2001. Antibacterial activity of smoke wood condensate against Aeromonas hydrophila, Yersinia enterocolitica and Listeria monocytogenes at low temperature. Food Microbiology 18, 387–393.

Relevant Website www.redarrowinternational.com Red Arrow International, LLC.

Traditional ZE Sikorski and I Sinkiewicz, Gdańsk University of Technology, Gdańsk, Poland r 2014 Elsevier Ltd. All rights reserved. This article is a revision of the previous edition article by ZE Sikorski, volume 3, pp 1265–1272, © 2004, Elsevier Ltd.

Glossary Antioxidant activity Decreases the rate of oxidation of meat lipids through smoking. The smoke components that have the highest antioxidant activity are phenols. Cold smoking The smoke temperature is in the range 12–25 °C. Health hazards Hazards associated with smoked foods that may be caused by carcinogenic components of wood smoke and toxic effects of pathogenic microflora not eliminated in the whole manufacturing process. Hot smoking The smoke temperature ranges from approximately 40–90 °C. Preservative action Decreases the rate of microbial spoilage of meats through smoking that depends on the

parameters of processing and the concentration of antimicrobial smoke components in the products. Sensory properties of smoked products Desirable changes caused through smoking – predominantly in the color, flavor, and texture of meats. Smoke composition Wood smoke consists of approximately 400 identified organic compounds, mainly phenols, aldehydes and ketones, carboxylic acids, aliphatic and aromatic hydrocarbons, alcohols, and esters. Smoke phenols A very diversified group of wood smoke constituents, containing monohydroxy- and polyhydroxyphenols, compounds with long side chains, and phenols with additional functional groups. Warm smoking The smoke temperature is in the range 25–45 °C.

Introduction Smoking, drying, and salting belong to the oldest methods of food preservation. Meat hung by the fire was preserved by a combination of drying and smoking. Often the raw material was first pickled in brine. In different regions of the world various procedures have been developed, best suited for treating meats and fish for specific purposes. Smoking extended the shelf life and imparted very desirable, new sensory properties to the products. The role of its preservative effect decreased with the advent of canning, modern chilling, and freezing, whereas the aspects of flavoring and safety gained importance. Nowadays smoking is applied in many forms to treat as much as 40–60% of the total amount of meat products. Traditional smoking involves the exposure of meat or meat products to smoke. The smoke is developed by smoldering wood either directly in the kiln below the hanging meat (Figure 1) or in an external generator. Its flow rate is controlled by natural draft depending on the construction of the smoking oven and on the weather conditions. In modern, automatic smokehouses it is forced by mechanical equipment. The temperature of the smoke is in the range 12–25 °C during cold smoking and 25–45 °C for warm smoking. In hot smoking, which should cause thermal denaturation of the meat proteins, the process may be carried out in different stages, at which the smoke temperature ranges from approximately 40–90 °C. The progress achieved in traditional smoking of food has focused in the recent several decades on the control of the composition of smoke, application of engineering principles to heat and mass transfer to shorten the processing time and affect the weight loss of the product, rational design of the

Encyclopedia of Meat Sciences, Volume 3

Figure 1 A traditional smoking oven. Courtesy of Łukasz Wisń iewski.

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process parameters, assurance of quality including safety of the smoked goods, modernization of equipment, and treatment of the spent smoke to avoid pollution of the environment.

Wood Smoke Generation and Composition The curing smoke develops due to partial burning of wood or other suitable material with a controlled oxygen supply. It is composed of air, water vapor, CO2, CO, nitrogen oxides, and a large number of different organic products of thermal degradation of hemicelluloses, cellulose, and lignin in temperature ranges of 180–300 °C, 260–350 °C, and 300–500 °C, respectively. Some of these products undergo oxidation at temperature reaching up to 900 °C. The yield and chemical composition of smoke depends more on the temperature and oxygen concentration in the zones of degradation and oxidation than on the humidity and kind of wood. Generally, smoke is made from hardwood, mainly oak and beech. However, for imparting specific color or flavor to some products, wood of other trees that are rich in resins, including coniferous as well as heather, may also be used. According to legal requirements the wood shall be natural, and has not been subjected to any chemical treatment. In some areas, however, even bagasse and coconut husks are used. From the large number of constituents found in different smoke condensates and extracts, approximately 400 organic compounds have been unequivocally identified. These include approximately 85 phenols, 110 aldehydes and ketones, 65 carboxylic acids, 20 aliphatic hydrocarbons, 80 aromatic hydrocarbons, and a number of alcohols, esters, and other compounds. The phenol fraction is a very diversified group, containing among others, different compounds with long side chains, polyhydroxyphenols, as well as phenols with additional functional groups. It has been separated into approximately 240 components. The compounds present in the highest concentrations are listed in Table 1. In the carbonyl fraction of wood smoke, the following compounds have been identified: formaldehyde, acetaldehyde, hydroxyacetaldehyde, acetone, hydroxyacetone, furfural, 5-methylfurfural, furanone, benzaldehyde, methylpropanal, and 3-methyl-2-cyclopenten-1-one. The fraction of acids consists of approximately 80% of acetic acid and includes formic, propionic, valeric, 4-oxovaleric, butyric, oxalic, malonic,

Table 1 The phenolic compounds present in wood smoke in the highest concentrations Guaiacol, 4-methylguaiacol, 4-ethylguaiacol, 4-vinylguaiacol, phenol, m-cresol, o-cresol, 3-ethylphenol, 2,5-dimethylphenol, syringol, 4-methylsyringol, 4-vinylsyringol, syringaldehyde, 1-(4-hydroxy-3,5-dimetoxyphenylo)-2-propanon, 1-(4-hydroxy-3,5-dimetoxyphenylo)-1-propanon, 1-(4-hydroxy-3,5-dimetoxyphenylo)-2-etanon, pirocatechin, 3-metoxypirocatechin, 4-methylpirocatechin, resorcinol, pyrogallol, 4-trans-propenylsyringol, hydroquinone.

maleic, fumaric, succinic acid, as well as various ketocarboxylic acids. In the alcohol fraction, methanol, ethanol, allylalcohol, n-amyl alcohol, 2-pentanol, 3-methyl-3-buten-1-ol, 3-methyl1-butanol, 2-hexanol, 2,4-pentadiol, and 1-heptanol have been identified. The ester fraction of wood smoke contains at least the methyl esters of formic, acetic, butyric, acrylic, propionic, 4-oksovaleric, heptanoic, and pelargonic acids, as well as ethyl and butyl acetates, ethyl butyrate, and ethyl valerate. The fraction of hydrocarbons contains approximately 20 aliphatic compounds, mainly methane and ethene, and a large group of aromatic hydrocarbons which includes at least 61 identified polycyclic aromatic hydrocarbons (PAH). The contents of PAH can be substantially limited by keeping the temperature of smoke generation below 400 °C. Wood smoke also contains several O-heterocyclic and N-heterocyclic components.

Deposition on Smoked Goods The boiling point of most smoke components is higher than the temperature in the smokehouse. Therefore, approximately 90% of the total mass of all constituents is present in the smoke in the form of small liquid droplets, approximately 0.08–0.15 mm in diameter. They are dispersed in the gaseous phase. The concentration of different components in the gaseous and dispersed phases depends on the temperature. The solid particles and liquid droplets disperse light, so that the smoke concentration can be assayed by measuring its optical density. Owing to the Brownian motion the particles and droplets coalesce and settle under the effect of gravitational and centrifugal forces on the walls of the smoking oven, the duct between the generator and the kiln, as well as on the smoked products. The electrostatic charge of the particles and absorption in the wet surface contribute also somewhat to deposition on the meat. High humidity of the smoke increases the rate of smoke deposition. On wet surfaces, the deposition of the components of the vapor phase is more effective than that of the particles and droplets. A rise in temperature of the smoke increases the concentration of some volatile components in the vapor phase and thus accelerates their sorption by the meat that is being smoked. The quantity of compounds absorbed by the meat depends on the temperature, humidity, agitation, and composition of the smoke, the characteristics of the product′s surface, and the duration of smoking. Wet surfaces adsorb approximately 20 times more phenols than dry ones. The published data on the total amount of smoke components absorbed by meat products are incomplete and vary within a broad range. The content of phenols in different smoked sausages ranges from approximately 0.02–200 mg g−1. The composition of the fraction depends more on the conditions of processing, especially the humidity of the surface of the meats than on the concentration of individual phenols in the smoke. The quantity of formaldehyde in cold smoked goods may be as high as 20– 40 mg g−1. The amount of formaldehyde in different assortments of sausages may reach 2–50 mg g−1; the surface layers of some products may contain approximately five times more than the inner layer.

Smoking | Traditional

Diffusion and Interactions in the Smoked Meats Some compounds deposited on the humid meat surface stay there, while other diffuse into the deeper layers due to the concentration gradient. The diffusion rate is controlled also by the character of the surface, as well as by the properties of the meat and smoke compounds. Most phenols accumulate on the skin, on the sausage casing, and in the layer of the product several millimeters deep, especially in the fatty tissue. Carbonyl compounds and acids are rather equally distributed throughout the mass of some smoked meat products. The chemically reactive phenols and carbonyls may be involved in polymerizations and react with amino and thiol groups in proteins and peptides. Furthermore, the phenols absorbed by the meat can be oxidized. The contents of guaiacol and phenol in smoked sausages stored for one month may decrease by approximately 35%. Because of comparatively low concentration of these absorbed components their reactions with meat proteins do not have any significant impact on the nutritive value of the products. However, the carbonyl-amino reactions and oxidation add to the desirable color formation.

The Effect of Smoking on the Shelf Life of Meat Products Antimicrobial Activity The shelf life of smoked products depends on the effect of heat pasteurization, level of water activity, as well as on the antibacterial and antioxidant properties of smoke components. Thus the preservative effect is obviously related to the concentration of salt due to presmoking treatment, the time– temperature regime and loss of water during processing, as well as the composition and quantity of smoke deposited on the meat. Cured and heavily smoked products are stable for several months at room temperature. Mild conditions of processing as applied in modern manufacturing of frankfurters do not exert such a high preservative effect. Smoking of frankfurters at internal temperature of 60–76 °C for 30 min reduces the total number of aerobic bacteria by approximately two log cycles, higher temperature and longer processing time being slightly more effective. Smoke components retard the proliferation of bacteria in cold stored frankfurters. Natural smoking can delay the onset of greening of frankfurters caused by Leuconostoc mesenteroides during storage. Various smoke constituents in concentrations similar to those in smoked goods prevent the proliferation of microorganisms. To the most active antimicrobial agents of wood smoke belong guaiacol and its methyl and propyl derivatives, creosol, pyrocatechol, methylpyrocatechol, and pyrogallol and its methyl ether. The presence of an aldehyde group in a phenolic compound increases the antimicrobial activity. Formaldehyde arrests the growth of Clostridium botulinum in the concentration of 40 mg cm−3. However, the smoke components present in lightly smoked foods stored under vacuum are not effective enough to inhibit the formation of C. botulinum toxin. Adding 8% of liquid smoke containing in 1 cm3 approximately 1.4–4.0 mg of phenols and 20–70 mg of

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carbonyl compounds to raw minced beef, may significantly reduce the number of viable cells of Escherichia coli O157 H7 after 3 days at 4 °C. Several of the most thermo-tolerant Staphylococcus epidermis do not survive commercial hot smoking on inoculated rainbow trout. In cold smoked salmon, the growth of Listeria monocytogenes was found to be inhibited proportionally to the smoking time – 12 h of smoking reduced the population by three log cycles. However, well-adapted strains may persist in the smokehouse environment, so that L. monocytogenes can often be found in vacuum-packaged cold smoked salmon. The most sensitive to smoke are generally the vegetative forms of bacteria. Molds are considerably resistant, although their development may be restrained by several phenolic compounds. A large population of molds and yeasts may survive in frankfurters smoked 30 min at an internal temperature of 67 °C. Smoking has little effect on the yeast count in the early stages of manufacturing of fermented sausages. However, in stored products the population of yeasts is lower in smoked sausages than in unsmoked controls.

Antioxidant Activity The antioxidant effect of smoking was noticed by observing that smoked meats and fish were resistant to oxidative rancidity. Among the smoke components that have the highest antioxidant activity are phenols. The true antioxidants (AH), even in very low concentration, inhibit lipid oxidation by inactivating the radicals (R•) capable of initiating the chain reaction R • þ AH→RH þ A • or the secondary radicals produced in the process of lipid oxidation (LO• or LOO•) LOO• þ AH→LOOH þ A • AH are able to react with the free radicals faster than the polyenoic fatty acids and thus protect the acids from being pulled into the chain reaction. However, they are ineffective in inactivating the highly reactive •OH radicals. These radicals, because of their reactivity, attack rather the abundant fatty acids instead of the antioxidants present in low concentration. The phenolic AH inactivate the free radicals by donating the hydrogen atom of their OH group (Figure 2). The phenolic radical formed in the reaction has a low reactivity due to resonance delocalization of the radical function. The most active phenolic smoke antioxidants are pyrogallol, resorcinol, 4methylguaiacol, 4-vinylguaiacol, and 4-trans-propenylsyringol. Less active are guaiacol, syringol, 4-methylsyringol, and 4-vinylsyringol.

The Role of Smoke in Developing Characteristic Sensory Properties of Smoked Goods The desirable sensory properties of smoked meats result from the concerted action of the components of the meat, salting or curing, predrying, smoking, and heating. The smoke compounds induce smoky color and flavor. They also interact with

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Smoking | Traditional

O•

OH LOO•

+

LOOH

+

O

O H •

•

H Figure 2 The inactivation of free radicals by phenolic compounds.

the nitrogenous meat constituents thus affecting some texture changes. The color developed on the surface of the products is caused by colored smoke components and their interactions with the meat. Its intensity is primarily related to the optical density of the smoke and the duration of smoking. It increases at high smoke temperature and velocity. High temperature favors the development of dark color, because the rate of polymerization of the components, mainly phenols and of the carbonyl-amino reactions in the smoke itself and between smoke compounds and amino acid residues in the meat increases with temperature. The higher the temperature and water activity of the surface of small-calibre Brűhwurst, within limits set by other technological requirements, the darker is the color of the sausages. The kind of wood used for smoke generation also affects the color. Smoking with beech, maple, ash, sycamore, or lime tree smoke leads to golden-yellow color; yellow-brownish tint comes from oak, nut, and alder smoke. Products treated with smoke from coniferous wood have a dark coloration. The dominant factors responsible for the smoky flavor are the smoke compounds themselves, mainly the phenols. The desirable flavor is associated with the presence of a mixture of syringol and 4-methylsyringol, although 4-allylsyringol, guaiacol, 4-methylguaiacol, and trans-isoeugenol also contribute to the typical sensory sensation. However, the multitude of variations of the smoky flavor is probably due to the contribution of different carbonyl compounds, furans, and other constituents not yet identified.

Health Hazards Induced by Smoking of Foods The health hazards associated with smoked foods are related to the presence of carcinogenic components in wood smoke and smoked meats – PAH, N-nitroso compounds, and possibly heterocyclic aromatic amines, as well as to the toxic effects of pathogenic microflora not eliminated in the whole manufacturing process. Wood smoke contains different PAH with a wide range of molecular weights (MW). The low-molecular members of this group, below MW 216, are not regarded as carcinogenic, contrary to many heavy MW PAH. Very mutagenic and carcinogenic is benzo(a)pyrene (BaP); until recently it was

recognized as an indicator of carcinogenic PAH in wood smoke and smoked products. However, in 2008 the European Food Safety Authority stated that BaP alone is not suitable for use as the only marker of the contents of PAH in foods because, in approximately 30% of a very large number of investigated samples, no BaP could be found, although there were numerous other PAH present. The sum of the concentration of BaP, benz(a)anthracene, benzo(b)fluoranthene, and chrysene (PAH4) serve the purpose better, or else PAH8, i.e. the sum of PAH4 plus the concentration of benzo(k)fluoranthene, benzo(g,h,i)perylene, dibenzo(a,h)anthracene, and indeno(1,2,3-cd)pirene. In the Commission Regulation (EU) of 2011, a maximum concentration of BaP in smoked meat and meat products has been maintained for the present (5 ng g−1 until 31 August 2014 and 2 ng g−1 after this date). However, additionally the upper limit for PAH4 has been introduced (30 ng g−1 from 1 September 2012 until 31 August 2014, and 12 ng g−1 after this date). Among PAH isolated from smoked products are mainly compounds with a MW less than 216. In various smoked meat products their total mass may be from approximately 30–250 times larger, whereas that of the heavy PAH approximately 10 times larger than that of BaP. The contents of BaP in hot smoked sausages is usually below 1 ng g−1, but in some black smoked products it may reach 55 ng g−1. In flame-grilled sausages, BaP has been found in concentrations of approximately 20–40 ng g−1. The contents of BaP in barbecued pork and beef may be in the range 1.5– 10.5 ng g−1, and in charcoal-broiled steaks 5–8 ng g−1. In various foods nitropolycyclic aromatic hydrocarbons have also been identified. In smoked sausages the contents of 1-nitropyrene, 2-nitronaphtalene, and 2-nitrofluorene has been found to be approximately 4, 8, and 20 ng g−1. This is comparable to the contents of these compounds in roasted coffee beans of approximately 2, 4, and 30 ng g−1. Smoked cured meat products contain a number of volatile and nonvolatile N-nitroso compounds, most of which are carcinogenic in laboratory animals. The aldehydes of smoke can react with cysteamine and with cysteine yielding various thiazolidine precursors that can be easily nitrosated. The reaction of formaldehyde with cysteamine and cysteine leads to thiazolidine and thiazolidine-4-carboxylic acid, respectively, which, on nitrosation turn into N-nitrosothiazolidine and N-nitrosothiazolidine-4-carboxylic acid. Minute amounts of these compounds occur in smoked meats. In the presence of glycolaldehyde from smoke 2-(hydroxymethyl)-N-nitrosothiazolidine and 2-(hydroxymethyl)-N-nitrosothiazolidine-4carboxylic acid (HMNTCA) may be formed. In smoked ham, sausages, salami, pepperoni, and poultry products the contents of HMNTCA may be from approximately 10–260 ng g−1. Generally the concentration of these compounds is higher in meats smoked in traditional ovens than in products processed in modern smokehouses supplied with smoke from external generators. The total amount of various N-nitroso compounds in smoked fried bacon, some of which still unidentified, has been reported to be 430–6800 ng g−1. Heterocyclic aromatic amines, known to be generated in pyrolytic reactions of amino acids and proteins and in nonenzymatic browning, are present in very heavily smoked foods in amounts lower than 1 ng g−1.

Smoking | Traditional The hazards associated with the effects of pathogenic microflora in smoked foods depend on the initial bacterial contamination of the raw materials, on the bacteriostatic and bacteriocidic action of all processing steps, and on the effectiveness of the applied systems of quality assurance, e.g., the hazard analysis and critical control points.

The Equipment Smoke Generators Traditional smoking is carried out in different countries using a variety of smokehouses. The traditional kilns, as shown earlier in Figure 1, are used only in artisan meat processing. In an advanced type of kiln extending over two storeys of a building distinct zones with different temperatures are created. Heat is generated by burning gas, but smoke is still produced in the lower section of the kiln. Modern smokehouses are supplied with smoke produced in conditions that favor the formation of desirable components and minimize the generation of PAH. In contemporary smoldering-type generators, the wood chips, shavings or sawdust are fed automatically on a grated fire bed or electrically heated plate. The sawdust or chips of wood of standardized water content and mesh size are available commercially. The temperature of the glowing pile is controlled by the humidity of the sawdust and the rate of air flow; by using material of approximately 50% humidity and limiting the air flow, the temperature may be reduced to approximately 600 °C. Because of the relatively high temperature of generation, the smoke is rich in phenols and has fully developed aroma. However, formation of PAH cannot be avoided if the temperature of the process exceeds 400 °C. In a friction-type apparatus, the heat necessary for thermal degradation of wood is due to pressing of a log against a rotating drum or disk. The temperature at the friction interface can be controlled by varying the pressure exerted on the log or the rotation rate of the rotor. It is generally below 400 °C. In such conditions the thermal degradation of lignin and the oxidation of the reaction products is not as advanced as in a smoldering pile of sawdust, thus the aroma of the smoke may be slightly different. These conditions, however, minimize the development of PAH. Various friction generators are available, especially for rather small smoking chambers. Wood smoke can be also produced in a hydropyrolytic process by treating sawdust or chips with superheated steam at 250–390 °C. The smoke developed at this temperature is rich in carboxylic acids and carbonyl compounds, but relatively poor in phenols. Its composition can be controlled by adjusting the temperature of the steam, the flow of air, and the rate of feeding the sawdust.

Smokehouses In a traditional kiln, the operator controls the processing parameters under different weather conditions by appropriate feeding of the fireplace with wood logs, chips, and sawdust, opening or closing the doors and vents, and reversing the rods carrying the smoked sausages. Modern smokehouses are built

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to utilize the full application of the engineering principles of heat and mass transfer. They are heated by steam, gas or electricity and equipped with devices for forced air and smoke circulation at controlled velocity. The circulation of smoke provides uniform thermal and flow conditions in all parts of the kiln. The temperature, humidity, and density of the air/ smoke, as well as the process time are adjusted to requirements depending on the desired properties of the products. Smokehouses used for processing cooked sausages are equipped with a hot water or steam injection systems and a cooling water spray, so that smoking, cooking, and cooling can be carried out in the same kiln. The smoke supplied from a generator is often conditioned by a water spray to control its temperature and humidity, and to separate out some tar fractions and soot. The material to be smoked is usually hung on rods and introduced by trolleys into the kiln or tunnel (Figure 3). Some kilns can be loaded through the front door and unloaded from the back side – this is convenient for a rational organization of the process. The exhaust gases, after leaving the smokehouse, are cleaned before entering the atmosphere. Some installations comprise three stages – an electrofilter, a fibrous filter, and activated charcoal. Other systems use afterburners to oxidize the components of the spent smoke at 800–1500 °C and some use temperature approximately 600 °C in the presence of a catalyst. Many smokehouses are equipped with installations for automatic cleaning.

Smoking Procedures Various procedures are used in the industry and in artisan meat processing to produce smoked foods of desired sensory properties and shelf life. Traditional procedures are based on practical experience of generations of meat processors. Skilled, experienced personnel are required to run the processes in a smoking oven at different weather conditions. In mass production of popular items, like frankfurters, the process is carried out in automatic smokehouses; the parameters are based on results of research and are computer-controlled. Some selected examples of different procedures are given below. Cold smoking is used mainly in manufacturing of raw, fermented sausages, made from cured meats. The smoke at 12–25 °C and controlled humidity is applied for several hours or days, depending on the assortment of produce. When smoking salami, the sausage links are first surface-dried for 1 day at 12 °C in low-density smoke. This is followed by 5 days of smoking in dense smoke at 15–22 °C, and finished within 2 days in a somewhat colder and less dense smoke. For smoked bacon, the cured cuts are soaked for 3–4 h in cold, running water, washed in water at 30–40 °C, hung on hooks for 12–24 h to drip and for surface drying, smoked for 24–48 h at 25–35 °C until the skin and meat surface turns dark brown, and cooled to below 18 °C. The product yield is approximately 90% in relation to the weight of the cured bacon. When smoking frankfurters, the first phase is tempering at 32–38 °C, which is intended to remove the surface moisture to ensure uniform color development of the product. Smoking properly in dense smoke of controlled humidity brings the

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Smoking | Traditional

Figure 3 A modern smokehouse: (1) flow direction of the smoke and (2) smoke generator. Courtesy of Łukasz Wisń iewski.

internal temperature of the sausages to 60–68 °C and imparts the desirable smoky color and flavor. It usually lasts for approximately 1–1.5 h. This is followed by cooking in hot water or steam and by chilling. Smoking cooked sausages at a too high temperature may cause excessive fat and weight loss. This may lead to development of creased surfaces of the sausages and loss of uniformity of color. In manufacturing jagdwurst the sausage batter made of cured pork, beef meat (9:1), and spices is stuffed into natural casings with a diameter of up to 32 mm. The links, 18–20 cm long, are hung for 12 h at 2–6 °C or 2–3 h at room temperature for setting, smoked for 80–90 min at 80 °C, dry-heated at 85 °C during 25 min to reach an internal temperature of 68– 70 °C with a brown surface color, chilled to 18 °C, smoked again at 24–32 °C for 12 h to a darker-brown color, dried at 14–18 °C at a relative humidity of 75–80% during 6–8 days to a final water content of 55–57%, exposed to final smoking at 24–32 °C for 2–3 h, and cooled to below 18 °C. The yield of the sausage is approximately 59% in relation to the weight of the cured meat. Kabanos, a delicatessen-type, spicy sausage, is produced by stuffing the sausage batter made of cured pork and spices into natural casings of 22 mm in diameter, setting the 60–70 cm long links for 12 h at 2–6 °C or for 30–60 min at room temperature, followed by 50–60 min of hot smoking, 20 min of dry heating to a core temperature 69–70 °C and dark brown color, cooling, and drying at 12–18 °C and 75–80% relative humidity for 5–7 days. The yield of the sausage is 55% relative to cured meat. Traditional Xinjiang smoked horsemeat is made by soaking specially selected parts of the carcass for 1 h in cold

water, adding 3% salt, 1% sugar, and 0.04% NaNO3, holding for 3–5 days at 2–4 °C, smoking for 5–6 h at a smoke temperature of 60 °C, and steaming for about 1.5 h at a meat temperature 90–100 °C. The smoked product is packed in cans, sterilized, and cooled. It has a dark brown surface and is dark red inside.

See also: Human Nutrition: Cancer Health Concerns. Microbiological Safety of Meat: Clostridium botulinum and Botulism; Listeria monocytogenes; Pathogenic Escherichia coli; Yeasts and Molds. Processing Equipment: Smoking and Cooking Equipment. Sausages, Types of: Dry and Semidry; Emulsion. Sensory and Meat Quality, Optimization of. Smoking: Liquid Smoke (Smoke Condensate) Application. Spoilage, Factors Affecting: Oxidative and Enzymatic

Further Reading Andrée, A., Jira, W., Schwind, K.-H., Wagner, H., Schwägele, F., 2010. Chemical safety of meat and meat products. Meat Science 86, 38–48. Bartoszek, A., 2007. Mutagenic, carcinogenic, and chemopreventive compounds in foods. In: Sikorski, Z.E. (Ed.), Chemical and Functional Properties of Food Components, third ed. Boca Raton, FL: CRC Press, pp. 451–486. Doe, P., Sikorski, Z., Haard, N., Olley, J., Pan, B.S., 1998. Basic principles. In: Doe, P.E. (Ed.), Fish Drying and Smoking. Production and Quality. Lancaster, PA: Technomic Publishing Co. Inc, pp. 13–45. Kołakowski, E. (Ed.), 2012. Technology of Food Smoking (in Polish). Warszawa: Powszechne Wydawnictwo Rolnicze i Lesń e.

Smoking | Traditional Miler, K.M.B., Sikorski, Z.E., 1990. Smoking. In: Sikorski, Z.E. (Ed.), Seafood: Resources, Nutritional Composition, and Preservation. Boca Raton, FL: CRC Press, pp. 163–180. Potthast, K., 1978. Verfahren des Räucherns und ihr Einfluss auf den Gehalt an 3,4-Benzpyren und anderen Inhaltsstoffen des Räucherrauches in geräucherten Fleischerzeugnissen. Die Fleischwirtschaft 58 (3), 340, 342–348. Potthast, K., 1979. Einfluss der Räuchertechnologie auf die vollständige Zusammensetzung der polycyclischen Kohlenwasserstoffe in geräucherten

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Fleischwaren, in Rauchkondensaten und in den Abgasen von Räucheranlagen. Die Fleischwirtschaft 59 (10), 1515–1523. Sikorski, Z.E., Kołakowski, E., 2010. Smoking. In: Toldra, F. (Ed.), Handbook of Meat Processing. Ames, IA: Wiley-Blackwell, pp. 231–245. Tóth, L., Potthast, K., 1984. Chemical aspects of the smoking of meat and meat products. In: Chichester, C.O., Mrak, E.M.K., Schweigert, B.S. (Eds.), Advances in Food Research, vol. 29. New York: Academic Press Inc., pp. 87–158.

SPECIES OF MEAT ANIMALS

Contents Cattle Finfish Game and Exotic Animals Meat Animals, Origin and Domestication Pigs Poultry Sheep and Goats Shellfish

Cattle MA Price, University of Alberta, Edmonton, AB, Canada r 2014 Elsevier Ltd. All rights reserved.

Glossary Biological type The commercially important physical characteristics of a beef animal. Carcass The primary commercial portion of a beef animal after dressing (removal of the blood, head, feet, hide, and internal organs). Cutability The proportion of saleable meat in the carcass. Dressing percentage The weight of the carcass expressed as a percentage of the live weight of the animal. Finishing Feeding to achieve the appropriate level of subcutaneous fat or finish for the target market.

Introduction All types of cattle, irrespective of whether their primary purpose is meat, milk, draft power, or some combination of these, are used ultimately in beef production. Consequently, a wide variety of shapes, sizes, body compositions, and ages of cattle consigned to abattoirs are found around the world. Some of them have been bred and managed specifically for beef production, whereas others, including culled breeding stock, produce beef as a by-product. This article is concerned mainly with the wide variety of breed types of cattle used for beef production in the developed world. In much of the developing world, cattle are not used primarily for beef production, and many different regional types have evolved that are suited to their particular local functions and management systems.

Biological Types of Beef Cattle Although the word ‘breed’ is used in common parlance to describe distinct types of cattle, it is not a completely useful or

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Heterosis The advantage conferred by crossbreeding measured as the difference between the offspring and the midparent mean for the trait; it is also known as hybrid vigor. Inbreeding Mating of animals that are more closely related than average in the population. Marbling The fat within the muscles. Net feed efficiency, also known as residual feed intake The difference between expected feed intake and actual feed intake based on an animal's live weight and growth rate. Offal All parts of the animal other than the carcass.

biologically meaningful term. In the past few centuries in particular, livestock (and pet) owners had gathered together groups of their animals with similar phenotypes and kept a formal registry of their progeny. This group of animals was then referred to as a ‘breed,’ and members of the breed were normally descendants of the original group. A deliberate policy of inbreeding close relatives was often followed to fix the ‘type,’ i.e., to ensure that the offspring conformed to the distinctive phenotype of the breed. An unavoidable by-product of this process was inbreeding depression whereby the purebred animals were less fit in an evolutionary sense and tended to have poorer reproductive and growth performance than their non-inbred relatives. Crossbreeding nullified this inbreeding depression through heterosis or hybrid vigor, which removed the constraints of inbreeding. Today, several species of cattle (genus Bos), comprising hundreds of major and minor breeds, are owned and used by farmers around the world. Commercial crossbreeding of these cattle can result in a wide variety of sizes and shapes, and the use of four genders (male, female, castrated male, and spayed female) and a broad range of ages and weights at harvest

Encyclopedia of Meat Sciences, Volume 3

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Figure 1 A pair of Hereford bulls. Reproduced with permission from the Canadian Hereford Association.

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Figure 3 A Simmental cow and calf. Reproduced with permission from the Canadian Simmental Association.

Figure 2 A Black Angus cow and calf. Reproduced with permission from the Canadian Angus Association.

further exacerbates the complexity of raw material entering the beef chain. Clearly, in trying to categorize the production traits of cattle, ‘breed’ is far too unwieldy a descriptor. Instead, the term ‘biological type’ is preferred and is used here to indicate phenotype in terms of temperament, mature body size, muscularity, and propensity to fatten, which are the most obvious traits of market-ready beef animals. Many other traits, such as libido, fertility, calving ease, and lactation, are of enormous importance to a beef producer, but they are not considered here. A number of very broad ‘biological type’ descriptors are commonly used in the beef industries of the developed world, including the following:

•

•

‘British’ refer to cattle originating in Great Britain, developed specifically for beef production off pasture, and typified as Hereford (Figure 1), Angus (Figure 2), and Shorthorn. Traditionally, they tend to be of medium body size and muscling with a relatively high propensity to fatten and a usually docile temperament. ‘Continental’ or ‘European’ refer to the multipurpose cattle from the European continent, typified by breeds, such as Simmental (Figure 3), Maine-Anjou (Figure 4), Charolais (Figure 5), and Gelbvieh. They are generally larger than the

Figure 4 A Maine-Anjou cow and calf. Reproduced with permission from the Canadian Maine-Anjou Association.

Figure 5 A Charolais bull. Reproduced with permission from the Canadian Charolais Association.

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Species of Meat Animals | Cattle

Figure 8 A Zebu bull. Photograph: Mick Price. Figure 6 A Chianina bull. Photograph: Walt Browarny.

Figure 7 A Holstein bull. Photograph: Patty Jones.

•

•

•

British cattle, with heavier muscling, a lower propensity to fatten, and less docile temperament. A subset of this group, sometimes referred to as the Italian White breeds (e.g., Romagnola, Marchigiana, and Chianina (Figure 6)), consists of very large cattle with a very low propensity to fatten. ‘Dairy type’ refers to cattle that have been bred primarily for milk production. They are characterized by light muscling and a low propensity to deposit subcutaneous fat, but they vary widely in mature body size from small (Jersey) to large (Holstein-Friesian). They are also characterized by a higher propensity than beef-type cattle to deposit intramuscular (marbling) and internal fats, including body cavity and kidney fat. Dairy bulls (Figure 7) are commonly described as having unpredictable and mean temperaments. ‘Dual purpose’ is a term applied to cattle bred to produce both milk and beef. They tend to be of medium to large body size (Brown Swiss, British and Dutch Friesians, Salers, and Normande) with moderate muscling and propensity to fatten. Temperament depends on the biological type of cattle involved. ‘Zebu’ is a general term applied to cattle of the Bos indicus species (Figure 8). They vary widely in mature body size and muscling but tend to have a lower propensity to fatten than taurine (Bos taurus) cattle and a more volatile disposition than British and Continental cattle. Their strengths include heat and insect tolerance, but their meat is slightly less

Figure 9 A Blonde d'Aquitaine bull. Photograph: Walt Browarny.

•

tender than that from taurine cattle. Maximum heterosis can be obtained by crossing B. indicus and B. taurus cattle. ‘Double muscled’ (muscularly hypertrophied) is a term used to describe cattle of any breed type exhibiting a particular genetic syndrome characterized by extremely heavy muscling. Although it results from a mutation in a single gene (a deletion in the ‘myostatin’ gene on bovine chromosome 2), this condition has very wide-reaching effects in terms of body composition and temperament. These cattle might be of any mature body size, depending on their breed type, but always show extremely high muscle-to-bone ratios and a very low propensity to fatten. They also typically exhibit fine bones, thin skin, and a nervous disposition. Some extremely heavily muscled breeds (e.g., Belgian Blue, Blonde d’Aquitaine (Figure 9), and Piedmontese) commonly carry the gene for this condition.

Cattle producers throughout the developed world have been slow to adopt crossbreeding and hybrid breeding systems. Although these are considered essential practices for most other species of livestock and poultry, beef and dairy producers still commonly use purebred or first cross (F1) cattle. However, in recent decades, two- and three-way crosses of cattle breeds have gained in popularity (sometimes resulting in a new ‘breed’) but hybrids, and particularly the use of hybrid bulls, are still considered a risky venture. Beef producers

Species of Meat Animals | Cattle have also relied to a greater extent on subjective (‘eyeball’) assessment to select sires and to cull dams than other livestock breeders. However, leaders in the beef industry have, over the past half century, increasingly incorporated objective methods of assessment into their genetic selection programs and have adopted crossbreeding to capitalize on heterosis and complementarity of traits. Measurements now include not only live weight and feed consumption but also ultrasonically assessed fat and muscle thickness. The cattle industries have also been quick to adopt the new sciences of genomics and proteomics to help identify and select genes associated with traits, such as fertility, residual (or net) feed efficiency, and carcass and meat quality, that have been difficult to improve using traditional methods. As technology and computing power have advanced and become more affordable, it has become possible to make comparisons among bulls at very young ages, which would have been impossible a few decades ago. These include the statistical assessment of expected progeny differences (EPDs) and deoxyribonucleic acid (DNA)-based genotyping and quantitative trait loci mapping to discover chromosomal regions and ultimately single-nucleotide polymorphisms associated with traits of interest to the breeder. Modern beef producers are very much aware of the importance of EPDs for a variety of traits in selecting bulls and culling heifers and cows and are increasingly requesting the incorporation of DNA-derived genomic information to assist in sire selection.

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severe enough to result in dark, firm, and dry (DFD) or even pale, soft, and exudative meat.

Mature Body Size Mature body size varies quite widely among the various biological types and genders of cattle. The lower range of sizes among traditional cattle is represented by the Dexter (a taurine breed originating in Ireland), with mature bulls typically less than 450 kg and mature cows approximately 100 kg less than the bulls. Although some specialty miniature cattle have been developed that are considerably smaller than the Dexter; they are not discussed in this article. At the extreme upper end of mature body size is the Chianina, also a taurine breed, from Italy, with mature bulls sometimes exceeding 1800 kg and cows reaching 1100 kg. It should be noted that the castrated male (steer) of all breed types would typically grow to be larger than the entire male, particularly in linear dimensions (height and length), but only at a very advanced age. Cattle that are raised specifically for beef production are usually marketed at a live weight considerably below their mature size, with each market having a preferred live weight and fatness. When cattle are marketed as culls from the dairy- or beef-breeding herd, they are more likely to have reached their mature body size.

Muscularity

Traits of Importance in Finished Beef Cattle Temperament Although temperament clearly has an environmental component (even the wildest of cattle can be tamed and the tamest of cattle made wild by the way they are handled), it is in part a genetically determined trait. Cattle handlers are very familiar with the ‘typical’ temperament of specific breeds of cattle and learn management techniques appropriate to those breed types. It can be generalized that zebu cattle and dairy breeds of bulls are more temperamental than the taurine beef breeds, with British beef breeds being more docile than continental cattle. Cattle exhibiting the ‘double-muscled’ trait are commonly stress susceptible. In management systems that involve frequent interactions between cattle and people, poor temperament is not likely to be a problem, partly because the animals become tamed through frequent handling and partly because only docile (or at least tamable) cattle are kept. In systems where there is minimal interaction with humans, it is possible for problem temperaments to remain unrecognized until animals are marketed, at which time nervous or aggressive temperaments can have important negative consequences. These cattle can be dangerous to handle and can injure or bruise themselves or other cattle during marketing or processing, resulting in removal and condemnation of the damaged tissue from the dressed carcass and possibly condemnation of the whole carcass. Even if physical damage is avoided, the stresses of marketing and transportation might be

At a common live weight, different biological types of cattle can vary widely in muscularity as a result of genetically determined differences in the muscle-to-bone ratio. In a ‘typical’ finished beef steer carcass, the ratio of muscle weight to bone weight is approximately 4:1, and almost all steer carcasses fall within the range of 3.5:1 (‘dairy type,’ e.g., Jersey) to 5:1 (‘heavily muscled’ type, e.g., Piedmontese). Gender also has an effect on muscle-to-bone ratio; bulls are more heavily muscled than steers, which are, in turn, more heavily muscled than heifers or cows. An extreme of muscle-to-bone ratio is found in cattle with the ‘double-muscled’ genotype. Bulls with this syndrome have been known to reach a carcass muscle-to-bone ratio as high as 9:1. The muscle-to-bone ratio is lowest at birth and gradually increases as animals mature. In an animal that is continually gaining weight, no matter how quickly or slowly, environmental effects, including nutrition and management, have little influence on muscle-to-bone ratio, because it is a genetically controlled function of live weight. However, if an animal loses weight, it is lost from muscle and fat in approximately equal amounts, rather than from the skeleton; therefore, weight loss results in a reduction in muscle-to-bone ratio. Although cattle of some genotypes contain more total muscle than others, biological-type differences in the distribution of muscles, for example, between high- and low-priced cuts of meat, are too small to be of any commercial importance. Traditional livestock judges have placed emphasis on this trait and it is most likely that a great deal of selection pressure, which should have been applied to truly important traits, has been wasted in its pursuit.

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Propensity to Fatten The propensity to fatten is also a genetically determined trait, but its expression is heavily dependent on environmental effects, particularly nutrition. In general, the types of cattle that have been selected strictly for beef production (e.g., the British beef types) have a greater proportion of their fat in the subcutaneous depot, and those that have been selected for dairy production have a greater proportion in the internal fat depots. Dairy types typically deposit more marbling fat than beef types. Some cattle, notably the Wagyu or Japanese Black breeds, have been selected specifically for their propensity to deposit intramuscular (marbling) fat without excessive amounts of fat in the other depots. In most cattle, however, marbling fat is the last to be deposited and reaches high levels only in cattle fed highenergy diets for prolonged periods. These cattle also exhibit high levels of fatness in the other depots.

Traits Determining the Value of Commercial Beef Animals

management system. Unfortunately, this flexibility is sometimes reduced by a producer's loyalty to one particular breed. The increasing popularity of grain feeding in North America following World War II gives an interesting insight into the ways in which beef producers tailor their product to suit the market. Straight-bred (i.e., purebred, but not registered) British-type beef cattle were the norm in most areas of North America in the early and middle parts of the twentieth century. These cattle had a high propensity to fatten, making them very suitable for grass finishing. Consequently, feeding them on high-energy (grain based) diets led to overfat carcasses at the desired carcass weight or underweight carcasses at the desired fatness. Because producers saw a strong economic advantage in feeding grain, the solution to this problem was to change the biological type of cattle to a larger, later-maturing (lower propensity to fatten) biological type. This led to a wide-scale importation of the larger, leaner, and faster-growing Continental cattle, such as Charolais, Simmental, and Limousin, which could be fed high-energy grain-based diets without becoming excessively fat at the target carcass weight.

Dressing percentage The value of commercial beef animals depends ultimately on the quantity and quality of meat they contain. In general, biological type has a major influence on meat quantity (size and body composition) but considerably less direct influence on meat quality. Biological type may, however, have a major indirect influence on meat quality through, for example, its effect on temperament leading to DFD beef. Biological type can also influence the thickness of muscle and fat in the carcass, and these together influence the rate of cooling following slaughter. Rapid cooling is a major cause of toughening, through cold shortening, in beef.

Quantity The quantity of beef in animals is determined by three factors: market weight, dressing percentage, and cutability. Dressing percentage is the weight of the carcass expressed as a percentage of the live weight of the animal and cutability is the weight of saleable meat expressed as a percentage of the weight of the carcass. In general, ‘meat’ constitutes approximately 35– 40% of a beef animal's live weight, but a number of factors can influence this.

Live weight and fatness The size and fatness of market-ready cattle entering the beef chain is determined by local preference. The challenge for all beef producers is to breed and manage their cattle to meet these demands, as failure to do so results in discounted prices. The biological type of cattle needs to be the one that reaches the optimum subcutaneous fat thickness at the optimum carcass weight in the particular management system. Beef from cattle marketed as culls does not have to meet these standards because it is used mainly in processed meat products. Because of the wide range in size and propensity to fatten among the different biological types of cattle, it is comparatively easy for producers to select types of cattle that quickly and efficiently reach the appropriate live weight and fatness in their particular

From the point of view of meat production, live animals consist of two parts: carcass and offal. These are not biological divisions and their definitions vary from time to time and place to place, but the carcass generally consists of the major muscles in the body and their associated bones and fat. In some places the tail, kidneys, and the kidney fat are defined as part of the carcass; in other places they are not. Regardless of how a ‘carcass’ is defined, ‘offal’ is always defined as everything in animals other than the carcass. The offal is further subdivided into edible and inedible components. Many factors affect dressing percentage; they can be conveniently categorized into those that affect the carcass weight and those that affect the liveweight. dressing percentage ¼

carcass weight  100 live weight

½1

An important factor affecting the numerator (carcass weight) is the definition of ‘carcass.’ Clearly, if the tails, kidneys, and kidney fat were defined as part of carcasses, then dressing percentage would be higher than it would be if they were defined as part of the offal. Also, the carcass itself can be weighed ‘hot’ (immediately after slaughter) or ‘cold’ (after cooling overnight at 1–3 1C). Before the advent of spray chilling (misting with cold water), a typical carcass used to lose approximately 2% of its weight during cooling; weight loss from spray-chilled carcasses is close to zero. Other major factors affecting carcass weight are fatness and muscularity (muscle-to-bone ratio): the fatter or more muscular a carcass is (all other things being equal), the higher is its dressing percentage. Both muscularity and propensity to fatten are under genetic control, so biological type influences dressing percentage. In practice, the range in muscularity in marketready cattle (apart from double-muscled animals) is not nearly as great as the range in fatness, and the majority of body fat is located in the carcass, so it can be further generalized that carcasses with greater dressing percentages are usually fatter. Factors influencing the proportion of the offal are also direct contributors to dressing percentage. These factors

Species of Meat Animals | Cattle include gut fill (the amount of undigested feed in the gastrointestinal tract), the weight and condition of the hide (wet/dry, hairy, and mud and manure caked), the proportion of bone, and, in case of females, pregnancy. Gut fill depends more on immediate preslaughter feeding than on biological type, but it might be that some cattle have greater appetites and can be expected to be ‘paunchier’ given the opportunity. This would tend to include the dairy types. Type of feed, particularly high energy versus low energy (e.g., grain vs. grass), influences gut fill because animals allowed to eat according to appetite consume a greater weight of low-energy feeds in an effort to optimize their daily energy intake. As a consequence, grassfinished cattle typically exhibit lower dressing percentages than grain-finished cattle. The weight of hide is a major contributor to the weight of the offal, and some biological types (e.g., zebu and double muscled) are known to have lighter hides and consequently higher dressing percentages. Geographical area and management system, particularly feedlot versus pasture finishing, might have a major influence on the amount of mud and manure caked on the hide. The presence of large horns, another trait of biological type, influences dressing percentage, but in practice it is common for horned cattle to be dehorned if they are to be finished in feedlots. The dressing percentage of a ‘typical’ steer (tail on the carcass, kidneys, and kidney fat in the offal) is in the order of 57–60% or 60–63% when kidneys and kidney fat are left in. Very fat or very muscular cattle could dress as high as 65%, but that would be exceptional. At the other extreme of normal cattle, culled cows typically have dressing percentages of approximately 48–53%, with the lower values being achieved by very lean, sick, or emaciated cattle, particularly of dairy type.

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The term ‘conformation’ has been widely used in the livestock industries but has no precise and generally accepted definition. It is derived from the concept of conforming to breed type, which was a criterion traditionally used to assess the acceptability of an animal. In modern parlance, it has to do with visually assessed shape, particularly in relation to muscle, but may in fact be greatly influenced by fatness and fat distribution. Muscularity, meatiness, and conformation are all subjective terms that attempt to convey how much ‘meat’ an animal carries. Unfortunately, meatiness – like beauty – may be in the eye of the beholder, and there is a poor relationship between visual assessments of conformation and actual cutability.

Meat Quality Although dressing percentage and cutability can be precisely defined (though the definitions vary from market to market), quality is a somewhat ethereal trait and must be subdivided into appearance and eating quality factors. Appearance factors include marbling, color, and texture of the meat and fat, and consumers naturally hope to use these as predictors of wholesomeness and eating quality. Unfortunately, there is little correlation between what can be seen and the ultimate taste and texture of the cooked product. Taste characteristics, particularly tenderness, juiciness, and flavor, are the ultimate measure of meat quality, but, because of their obviously subjective nature, they are very difficult to assess accurately and with repeatability and in any case cannot be known with certainty until the meat is eaten.

Appearance Cutability Carcass cutability can be defined in a number of ways, but it means the amount of saleable meat in the carcass generally expressed as a percentage of the carcass weight. It is largely determined by the amount of bone and excess fat that are removed from the carcass before retail. The actual value is strongly influenced by the cutting processes used. In some countries, all bones are removed before retail, but in most countries some cuts, for example, T-bone steak and standing rib roast, are marketed bone-in. Similarly, the amount of fat left on retail cuts is a matter of national or regional preference. Thus, to put absolute values on cutability would be misleading because the absolute value varies widely depending on geographical location. It is clear, however, that the influence of biological type on cutability can be profound because a carcass with a higher muscle-to-bone ratio or lower level of fatness has a correspondingly higher cutability. This biological-type effect is further influenced by the effects of age and slaughter weight on muscle-to-bone ratio and nutrition and management effects on carcass fatness. Some carcass grading systems include a ‘cutability estimate’ as a criterion of carcass merit. This figure is usually based on selected prime cuts, rather than on the whole carcass and therefore cannot be taken to indicate the total amount of meat available for retail sale. In general, 55–60% of the weight of beef carcasses is composed of muscle, with exceptionally muscular or lean carcasses exceeding this range and fat or lightly muscled carcasses falling short.

Many of the components of appearance, such as marbling, thickness, color, and texture of muscle and fat, are known to have little or no relationship to eating quality. Nevertheless, they are considered by consumers, or the retailers who often act in proxy for them, to be important quality traits in their own right, because they influence the perceptions and thus the buying decisions of consumers. A bright red lean color is perceived to be fresh and from young animals. Marbling – the flecks of fat that appear within meat – is the only appearance trait that gives any repeatable guide to eating quality and hence it has become an important determinant of value. Unfortunately, it is not a very reliable predictor because it accounts for only approximately 10–15% of the variation in tenderness and juiciness. It is also difficult to quantify precisely and is not consistently distributed within the carcass. Marbling is a late-maturing fat depot, meaning that fat is not deposited in this depot in appreciable amounts in very young cattle. The amount of marbling present in a carcass is also related to the total amount of fat: well-marbled carcasses tend to be fatter carcasses. However, there is a discernible breed effect, with the ‘dairy-type’ cattle having higher levels of marbling at constant total fatness and some specialty breeds, such as the Wagyu or Japanese Black, exhibiting very high levels of marbling. Breeds with consistently lower levels of marbling (Limousin, Piedmontese, and Blonde d'Aquitaine) tend to generally lack fat. Although marbling is not a reliable guide to eating quality, it has been noted that greater amounts of marbling result in less

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toughening in meat cooked to higher temperatures, giving rise to the view that well-marbled beef is more forgiving of a poor cook. Color and texture of muscle tend to be functions of age and immediate preslaughter stress levels, and these dwarf any genetic effects; however, the yellow color in beef fat has a genetic component as well as a nutritional component. The most common cause of yellow fat, other than liver disease, is the presence of β-carotene in solution in the fat. β-carotene is red in color (carrots and tomatoes) but appears yellow in dilute solution. It is found in green forage and is converted into the much paler vitamin A at the intestinal wall during absorption as well as in the liver. Some cattle, notably the ‘Channel Island’ breeds, Jersey and Guernsey, and the zebus, have yellower fat, probably through a reduced capacity to convert carotenoid pigments in the feed into vitamin A before storing it in the fat. It is notable that the milk of these cattle is also yellower, for the same reason. As both β-carotene and vitamin A are tasteless, their presence or absence has no direct effect on taste, although consumers may subconsciously ascribe superior taste to meat having fat of a preferred color. The concentration of β-carotene in the fat increases with age, particularly in an animal that has experienced cyclical storage and removal of fat during its life. Consequently, cull cows, which tend to be older and have experienced annual fluctuations in fatness, are associated with yellow fat. Their meat is not preferred, enhancing the myth that yellow fat causes poor eating quality.

Conclusions All cattle ultimately produce beef, and cattle come in a wide variety of shapes and sizes. Specialist beef breeders are increasingly moving away from purebreds and are using crossbreeding combined with sophisticated assessments of the genetic determinants of important traits. Breed or biological type can influence carcass and meat quality in a number of ways. Biological types differ in size and body composition (proportions of muscle, fat, and bone), and hence both the absolute and relative (through dressing percentage and cutability effects) amount of meat they produce. However, there is less intrinsic difference in the taste or texture of their meat, and a factor, such as carcass fat covering (insulation) could have a major indirect effect on tenderness through its effect on the rate of postmortem cooling and hence the extent of cold shortening. Fatter carcasses also tend to have more marbling, which might make the (admittedly weak) relationship between marbling and tenderness more of a coincidence rather than a cause-and-effect relationship. However, marbling does tend to ameliorate the deleterious effects of high endpoint temperature on meat tenderness. Feeding and management, which may be breed related, could also have minor influences on taste and texture; for example, in North America, Britishtype cattle are more likely to be finished extensively on grass, whereas European cattle are more likely to be finished intensively on grain. In general, biological type can have a major influence on the quantity and appearance of meat in bovine carcasses but considerably less direct influence on its taste and texture.

Taste The eating quality of beef is extremely complex. It is sometimes said of taste that ‘quality goes in after the hide comes off,’ in recognition of the fact that processing and postslaughter handling, including preparation and cooking, are far more important in determining eating quality than the biological type or management of the animal itself. Differences in eating quality among different muscles (retail cuts) and even within a single muscle completely transcend any differences found among live animals, irrespective of whether these differences result from biological type, age, gender, nutrition, or management factors. Eating quality is generally defined as a combination of tenderness, juiciness, and flavor, although each of these is, in turn, a complex of traits. Tenderness is generally accepted as the most important eating quality trait, and there are documented biological-type effects on certain aspects of tenderness. In particular, the zebu breeds have been shown to produce tougher beef than the taurine breeds, perhaps because of genetic differences in proteolytic enzyme systems that affect the progress of postmortem tenderization. It is known, for example, that zebu cattle have higher concentrations of the inhibitor calpastatin, which is related to toughness. However, it should be clearly recognized that these differences are much smaller than the differences found among muscles in the same animal or between carcasses that have been subjected to different postmortem handling. Rapidly cooled muscles experience cold toughening, whereas aging is a process that progressively tenderizes muscle. The heritability of tenderness is moderately high.

See also: Animal Breeding and Genetics: DNA Markers and Marker-Assisted Selection in the Genomic Era; Traditional Animal Breeding. By-Products: Edible, for Human Consumption; Hides and Skins; Inedible. Chemical and Physical Characteristics of Meat: Palatability. Classification of Carcasses: Beef Carcass Classification and Grading. Conversion of Muscle to Meat: Aging; Color and Texture Deviations; Rigor Mortis, Cold, and Rigor Shortening. Modeling in Meat Science: Meat Quality. Slaughter-Line Operation: Cattle; Poultry

Further Reading Basarab, J.A., Price, M.A., Aalhus, J.L., et al., 2003. Residual feed intake and body composition in young growing cattle. Canadian Journal of Animal Science 83, 189–204. Berg, R.T., Butterfield, R.M., 1976. New Concepts of Cattle Growth. Sydney: Sydney University Press. Cundiff, L.V., 2005. Beef cattle: Breeds and genetics. In: Pond, W.G., Bell, A.W. (Eds.), Encyclopedia of Animal Science. New York, NY: Dekker, pp. 74–76. Porter, V., 2002. Mason's World Dictionary of Livestock Breeds, Types, and Varieties, fifth ed. Wallingford: CABI Publishing. Price, M., 2009. Meat science. In animal and plant productivity. In: Robert, J.H. (Ed.), Encyclopedia of Life Support Systems (EOLSS), Developed under the auspices of UNESCO. Oxford: Eolss Publishers. Available at: http://www.eolss.net (accessed 07.01.14). Swatland, H.J., 1994. Structure and Development of Meat Animals and Poultry. Lancaster, PA: Technomic.

Species of Meat Animals | Cattle Thonney, M.L., 2005. Body composition: Breed and species effects. In: Pond, W.G., Bell, A.W. (Eds.), Encyclopedia of Animal Science. New York, NY: Dekker, pp. 155–158. Warriss, P.D., 2010. Meat Science: An Introductory Text, second ed. Wallingford: CABI Publishing.

Relevant Website http://cowcalf.cattle.ca/beef-cattle-breeds The Canadian Cattlemen's Association.

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Finfish XM Vilanova, Universitat Autònoma de Barcelona, Barcelona, Spain r 2014 Elsevier Ltd. All rights reserved. This article is a revision of the previous edition article by JM Tennyson, RS Winters, LS Andrews, volume 3, pp 1308–1316, © 2004, Elsevier Ltd.

Introduction Each of four production division groups is identified in a separate table that lists the fish by name (scientific and common), major location, maximum measurement (length, weight, and age), use, production (rank and total), and cooking method. According to the Food and Agriculture Organization of the United Nations (FAO), the estimated total world production of fishery commodities (e.g., fish and crustaceans) in 1000 metric tones (kt) was 98 627 in 1990; 116 412 in 1995, and 130 434 in 2000. These live weight-based production estimates excluded whales, seals, and other aquatic mammals and plants, but included aquaculture products. The 2000 world fisheries production (e.g., fish and crustaceans) by capture (wild) and aquaculture revealed that of the total of 130 434 kt, wild harvest accounted for 72.7% and aquaculture contributed 27.3%. In 2000, the top 10 world fisheries production countries, in decreasing order, were China, Peru, Japan, India, USA, Indonesia, Chile, Russian Federation, Thailand, and Norway. During this timeframe, China's total production was 41 568 kt, of which wild harvest and aquaculture accounted for 40.9% and 59.1%, respectively. An examination of the 2000 international trade in fisheries commodities by principal importers and exporters shows that the top 10 importers, in decreasing order, were Japan, USA, Spain, France, Italy, Germany, UK, Hong Kong, Denmark, and China. The top 10 exporters were Thailand, China, Norway, USA, Canada, Denmark, Chile, Taiwan, Spain, and Indonesia. Interestingly, USA, Spain, Denmark, and China were the numbers 2, 3, 9, and 10 importers, respectively, and they were also the numbers 4, 9, 6, and 2 exporters, respectively. A comparison of the disposition of the world fishery production indicates that in 1990, 1995, and 2000 the production increased from 98 627 to 116 412 and finally to 130 434 kt, in the respective years. Of the 130 434 kt, human consumption accounted for 74.1% divided by marketed fresh (53.7%), frozen (25.7%), cured (9.6%), and canned (11.0%). The remaining 3726 kt (25.9%) was for other purposes.

Definitions • Cartilaginous fishes: A classification of approximately 700 fish species (i.e., Class Chondrichthyes) that contains sharks, skates, rays, and chimaeras. • Finfish: This is a generic term for true fish. • Fish: The term fish includes finfish, crustaceans, other aquatic animals (e.g., alligators (?), frogs, turtles, and jellyfish) and molluscs.

336

• Sashimi: Thin slices of fresh (and previously frozen), raw fish that might be served with soy sauce and wasabi (horseradish). • Surimi: In general terms, this is minced fish tissue from which fat, off-odors, and colors have been eliminated and to which cryoprotectants (e.g., sugars and other additives) have been added before freezing of the meat. • True fishes: Generally, these fishes are cold-blooded, gillbreathing, aquatic bony vertebrates, usually with fins.

Capture (Wild) Production by Principal Species FAO's 2000 capture or catch (wild) data revealed production by principal species. Twenty-three of these species by the name (scientific and common), major location, maximum measurement (length, weight, and age), use, production (kt) (rank and total) in 2000, and cooking method are listed in Table 1.

World Aquaculture Production FAO's 2000 world aquaculture data listed the production for 18 finfish species. The production for these finfish species ranged from 3473 to 137 kt and yielded 19 024 kt; however, the first 6 finfish species' production ranged from 3473 to 1045 kt and produced 13 700 kt. These 18 principal aquaculture finfish species by the name (scientific and common), major location, maximum measurement (length, weight, and age), use, production (kt) (rank and total) in 2000, and cooking method are listed in Table 2.

Nutritional Content of Selected Groups of Finfish A review of the nutritional content of raw tissue from selected finfish was undertaken, and the finfish were divided into four groups based on their total energy content. Group 1 consisted of Atlantic mackerel, Pacific herring, Greenland halibut, eel (mixed species), and Atlantic salmon. Group 2 contained milkfish, Spanish mackerel, rainbow trout, channel catfish, whitefish (mixed species), European anchovy, carp, and bluefish. Group 3 was made up of yellowfin tuna and skipjack tuna. Group 4 comprised Atlantic cod, walleye pollock, and orange roughy. Subsequently, 11 nutrient values (i.e., water, energy, protein, total fat (lipid), calcium, iron, sodium, ascorbic acid (vitamin C), riboflavin, niacin, and cholesterol) were selected from each group of finfish and the data were averaged and reported in Table 3. A comparison of the total fat and cholesterol as well as the protein and water values was considered to be important because of the high levels of

Encyclopedia of Meat Sciences, Volume 3

doi:10.1016/B978-0-12-384731-7.00083-0

A. 50.0 cm B. 0.8 kg C. 20 years A. 2.4 m B. 200.0 kg C. 8 years

Temperate, marine waters in the Atlantic (e.g., the Barents Sea, around Iceland and Africa, and off Greenland and the USA) Brackish and marine tropical and subtropical seas worldwide except for the Mediterranean Sea

A. Micromesistius

poutassou B. Blue whiting (aka poutassou) A. Thunnus albacares B. Yellowfin tuna

Native to polar, marine waters near the Arctic pole; in the North Atlantic (e.g., in the Norwegian Sea and Gulf of Maine) and North Pacific (e.g., Korea)

Subtropical, marine waters of the Indo-Pacific area

A. Mallotus villosus B. Capelin

A. B.

A. B.

B. A. B.

Engraulis japonica) Japanese anchovy Trachurus murphyi Inca scad (aka Chilean jack mackerel) Trichiurus lepturus Atlantic cutlassfish (aka largehead hairtail) Scomber japonicus Chub mackerel

A. Engraulis japonicus (aka

A. Katsuwonus pelamis B. Skipjack tuna 1.1 m 34.5 kg 12 years 16.0 cm ND 3 years 70.0 cm ND 16 years 2.3 m 5.0 kg 15 years 64.0 cm 2.9 kg 18 years 25.2 cm ND 5 years

A. 45.0 cm B. 1.0 kg C. 11 years

Brackish and marine waters of moderate temperatures in the North Atlantic (e.g., from the Bay of Biscay to Ireland, Greenland, etc., and from Labrador to South Carolina) Worldwide (except for the Black and Mediterranean Seas) in marine waters of tropical and moderate temperatures In big schools near the surface of warm, marine waters of the Western Pacific (e.g., Sakhalin Island and Sea of Japan) Tropical, marine waters of the Pacific Ocean (e.g., off Chile and New Zealand) and Southwest Atlantic (e.g., Argentina) Native to subtropical, brackish and marine waters worldwide

A. Clupea harengus B. Atlantic herring

A. B. C. A. B. C. A. B. C. A. B. C. A. B. C. A. B. C.

A. 91.0 cm B. 1.4 kg C. 15 years

Polar, brackish, and marine waters from Alaska to the Sea of Japan and to California, USA, and near Baja California, Mexico

A. Theragra chalcogramma B. Walleye pollock

anchovy)

A. 20.0 cm B. ND C. 3 years

Maximum measurement A. Lengthd B. Weightd C. Aged

Subtropical, marine waters off the western coast of South America from Peru to Chile

Major locationd

A. 3 B. 2370 kt

A. 4 B. 1890 kt A. 5 B. 1726 kt

Fresh or processed (e.g., frozen and dried/salted) Fresh and manufactured (e.g., fish meal)

Fresh (including for sashimi) and processed (e.g., canned and smoked)

A. 11 B. 997 kt

A. 10 B. 1420 kt

A. 9 B. 1456 kt

A. 8 B. 1456 kt

A. 7 B. 1480 kt

A. 6 B. 1540 kt

A. 2 B. 3025 kt

Roe (egg-laden ovaries of fish) and frozen; further manufactured into surimi, etc Fresh or processed (e.g., smoked and canned)

Fresh and processed (e.g., into canned goods and fish meal) Fresh (e.g., for sashimi) and processed (e.g., dried/ salted and frozen) Fresh and processed (e.g., canned, smoked, and salted), and as a medicine Roe (egg-laden ovaries of fish) and processed (e.g., canned, dried, frozen, and fish meal) Fresh and manufactured (e.g., into fish oil)

A. 1 B. 11 276 kt

A. Ranke B. Total

Productiona

Fish meal (animal feed) fertilizer and oil

Used

Twenty-three selected finfish species including names, locations, measurements, 2000 catch (wild) production etc.

A. Engraulis ringens B. Anchoveta (aka Peruvian

A. Scientific B. Common

Namesa,b,c,d

Table 1

ND

ND

Fried

Baked, fried, etc.

Grilled and fried

ND

ND

ND

(Continued )

Broiled, fried, microwaved, etc.

Sautéed and steamed, etc.

ND

Cooking methodd

Species of Meat Animals | Finfish 337

Continued

niphonius B. Japanese seer (aka Japanese Spanish mackerel) A. Sardinops caeruleus (aka Sardinops sagax caeruleus) B. California pilchard (aka South American pilchard and Pacific sardine)

A. Scomberomorus

A. Brevoortia patronus B. Gulf menhaden

A. Engraulis encrasicolus B. European anchovy

A. Sprattus sprattus B. European sprat

A. Scomber scombrus B. Atlantic mackerel

A. Strangomera bentincki B. Araucanian herring

sardine)

A. Sardina pilchardus B. European pilchard (aka

A. Gadus morhua B. Atlantic cod

A. Scientific B. Common

Names

a,b,c,d

Table 1

Subtropical, marine waters (e.g., Indo-Pacific area) and has three lineages: (1) Southern Africa (ocellatus) and Australia (neopilchardus), (2) Chile (sagax) and California (caeruleus), and (3) Japan (melanostictus)

Native to temperate marine waters (e.g., of China, the Yellow Sea and the Sea of Japan)

Native to brackish and marine waters of moderate temperatures of the North Atlantic (e.g., Cape Hatteras to Ungave Bay and off the coasts of Greenland and Iceland) Native to the subtropical, fresh, brackish, and marine waters of the Northeast Atlantic (e.g., North, Adriatic and Black Seas) This species is found in schools (e.g., close to the surface) of subtropical, marine waters of the Southeast Pacific (e.g., near Chile) Temperate, brackish, and marine waters of the Atlantic Ocean (e.g., in the Baltic, Black, and Mediterranean Seas) Native to temperate, brackish, and marine waters of the Adriatic, Black, North, and Mediterranean Seas, etc. Native to subtropical, brackish, and marine waters of the Eastern Atlantic (e.g., Norway to South Africa), Mediterranean, and Black Seas, etc. In dense schools in subtropical, marine waters (e.g., the Gulf of Mexico)

Major locationd

25.0 cm ND 15 years 28.4 cm ND ND 60.0 cm 3.4 kg 17 years 16.0 cm ND 6 years 20.0 cm ND 3 years 35.0 cm ND ND 1.0 m 7.1 kg ND

A. 39.5 cm B. 0.5 kg C. 25 years

A. B. C. A. B. C. A. B. C. A. B. C. A. B. C. A. B. C. A. B. C.

A. 2.0 m B. 96.0 kg C. 25 years

Maximum measurement A. Lengthd B. Weightd C. Aged

Fresh and processed (e.g., canned, frozen, and fish meal)

Fresh and processed (e.g., canned, smoked, and frozen). Fresh and processed (e.g., frozen, canned, smoked, and fish meal). Fresh or processed (e.g., canned, dried, frozen, smoked, and fish meal) Fresh and processed (e.g., canned, salted, fish meal, and oil) Fresh (e.g., raw as sashimi)

Fresh and processed (e.g., canned, smoked, and frozen) Processed (e.g., fish meal for animal feed)

Fresh and processed (e.g., dried/salted and frozen)

Used

A. 20 B. 528 kt

A. 19 B. 539 kt

A. 18 B. 591 kt

A. 17 B. 605 kt

A. 16 B. 660 kt

A. 15 B. 674 kt

A. 14 B. 723 kt

A. 13 B. 943 kt

A. 12 B. 945 kt

A. Ranke B. Total

Productiona

Fried and broiled

Baked, broiled, and fried

ND

ND

Broiled and fried

Baked, broiled, fried, etc.

ND

Broiled, fried, and microwaved

Baked, broiled, steamed, etc.

Cooking methodd

338 Species of Meat Animals | Finfish

A. 46.0 cm B. ND C. 19 years

A. 2.5 m B. 210.0 kg C. 11 years A. 1.0 m B. 14.0 kg C. ND

Temperate, fresh, brackish, and marine waters (e.g., of the Arctic Sea and Pacific Ocean)

Originates in subtropical, marine waters of the Atlantic, Indian, and Pacific Oceans

This highly migratory species originates in tropical, marine waters (e.g., Indo-West Pacific area)

A. Thunnus obesus B. Bigeye tuna

A. Euthynnus affinis B. Kawakawa

Fresh and processed (e.g., canned, dried/salted, frozen, and smoked). Pacific herring are valued for roe and eggs laid on kelp. (The latter eggs when salted are termed kazunoko-kombu.) This fish is also valued as a Chinese medicine Fresh and processed (canned or frozen). The Japanese value this fish for sashimi Fresh and processed (e.g., canned, dried, frozen, salted, and smoked)

A. 23 B. 428 kt

A. 22 B. 433 kt

A. 21 B. 456 kt

ND

Baked, boiled, and fried

b

http://www.fao.org/fi http://www.cfsan.fda.gov/Bfrf/rfeO.html c Randolph, S., Synder, M., 1993. The Seafood List: FDA's Guide to Acceptable Market Names for Seafood Sold in Interstate Commerce 1993. Washington, DC: Office of Seafood, Food and Drug Administration. Superintendent of Documents. US Government Printing Office. d Froese, R., Pauly, D. (Eds.), 2003. Fish Base. Available at: www.fishbase.org (version 24 Oct 2003). e The original reference included production rankings (e.g., numbers 14, 18, and 21) that were nonfinfish species. For this table the production rankings were renumbered to reflect the top 23 finfish ranking. Abbreviations: aka, also known as; ND, no data. Source: Reproduced from Center for Food Safety and Applied Nutrition of the USA Food and Drug Administration; Food and Agricultural Organization of the United Nations.

a

Clupea pallasii) B. Pacific herring

A. Clupea pallasi (aka

Species of Meat Animals | Finfish 339

In fresh and brackish waters of moderate temperatures of Europe, Asia and China. The European subpopulation of this species is on the 2002 International Union for Conservation of Nature and Natural Resources (IUCN) Red List of Threatened Speciesf In fairly moderate waters of the Rift Valley lakes, West African Rivers (e.g., Benue), North America (farm raised), etc.

A. Carassius carassius B. Crucian carp

A. Chanos chanos B. Milkfish

Tropical, freshwater, brackish and marine species native to the Indo-Pacific area. Their range includes Asia, Japan, Australia, Red Sea, Africa, etc. They are also found from California to Galapagos

Tropical, fresh waters of Sungari, Liao, China, etc.

Tropical, fresh and brackish waters of India

A. Cirrhinus mrigala (aka

Cirrhinus cirrhosus) B. Mrigal A. Parabramis pekinensis B. White amur bream

Subtropical, fresh and brackish waters of Pakistan, Nepal, Myanmar, etc.

A. Catla catla B. Catla

A. Labeo rohita B. Rohu

Tilapia nilotica) B. Nile tilapia A. Salmo salar B. Atlantic salmon Fresh, brackish. and marine waters of moderate temperatures. This species' native habitat is the Western Atlantic (e.g., Quebec, Canada), Eastern Atlantic (e.g., Arctic Circle) and landlocked areas (e.g., Russia and North America). Atlantic salmon are pen raised (e.g., in Canada) Tropical, fresh and brackish waters of Pakistan, India, Nepal, etc.

Fresh waters of moderate temperatures (e.g., lowland rivers) of China and worldwide for aquacultural purposes

A. Hypophthalmichthys nobilis B. Bighead carp

A. Oreochromis niloticus (aka

Fresh waters of moderate temperatures worldwide, especially in the Black, Caspian, and Aral Seas, etc.

Lake Khanka, rivers of the People's Republic of China, western portions of the former USSR, USA, etc.

A. Ctenopharyngodon

idellus (aka Ctenopharyngodon idella) B. Grass carp A. Cyprinus carpio B. Common carp

Fresh waters of moderate temperatures in Asia, China, Europe, and USA

A. Hypophthalmichthys molitrix B. Silver carp

Names A. Scientific B. Common

Major locationd,e,g,h,i

A. B. C. A. B. C. A. B. C. A. B. C. A. B. C.

2.0 m 45.0 kg 10 years 1.8 m ND ND 1.0 m 12.7 kg ND 55.0 cm 4.1 kg ND 1.8 m 14.0 kg 15 years

40.0 cm ND ND 1.5 m 46.8 kg 13 years

1.2 m ND 24 years ND ND ND 64.0 cm 3.0 kg ND

A. B. C. A. B. C. A. B. C.

A. B. C. A. B. C.

1.3 me ND 10 yearse 1.5 m 45.0 kg 21 years

A. B. C. A. B. C.

Maximum measurement A. Lengthd,e,g B. Weightd,e C. Aged,e

Eighteen finfish species including names, locations, measurements, 2000 world aquaculture production, etc.

a,b,c,d,e,g

Table 2

A. 7 B. 884 kt

Fresh and processed (e.g., smoked, dried, and salted) Fresh

A. 12 B. 462 kt

A. 11 B. 512 kt ND

ND

A. 10 B. 573 kt

A. 9 B. 653 kt ND

ND

A. 6 B. 1045 kt

ND

A. 8 B. 795 kt

A. 5 B. 1379 kt

A. 4 B. 1637 kt

A. 3 B. 2718 kt

A. 2 B. 3447 kt

A. 1 B. 3473 kt

Productiona A. Rank B. Total

Fresh or processed frozen

ND

ND

Fresh

ND

Used

ND

ND

ND

ND

ND

Broiled, microwaved, etc.

ND

Baked, fried, etc.

ND

ND

Baked, fried, steamed, etc.

ND

Cooking methodd

340 Species of Meat Animals | Finfish

A. 1.5 m B. 0.8 kg C. ND

A. B. C. A. B. C. A. B. C.

Tropical, fresh, brackish and marine waters of Japan, Taiwan, Korea, China, etc.

Tropical, fresh waters of Mekong, Chao Phraya, Nanpangjiang, and Red River Subtropical, fresh waters of the Amur River basin and China

Subtropical, marine waters of the Northwest Pacific (e.g., from Japan to the Hawaiian Islands)

A. Cirrhinus molitorella B. Mud carp

A. Mylopharyngodon piceus B. Black carp

A. Serbia quinqueradiata B. King amberjack (aka

Fresh for sashimi

Fresh or processed (e.g., canned, smoked, and frozen) Fresh and processed (e.g., smoked and frozen) Fresh or further processed (e.g., smoked, canned, and frozen) Fresh and as prahoc (fish paste) ND

A. 18 B. 137 kt

A. 17 B. 171 kt

A. 16 B. 200 kt

A. 15 B. 220 kt

A. 14 B. 269 kt

A. 13 B. 448 kt

ND

ND

ND

Baked, broiled, and steamed

Baked, broiled, fried, etc.

Baked, boiled, microwaved, steamed, etc.

b

http://www.fao.org/fi http://www.cfsan.fda.gov/Bfrf/rfeO.html c Randolph, S., Synder, M., 1993. The Seafood List: FDA's Guide to Acceptable Market Names for Seafood Sold in Interstate Commerce 1993. Washington, DC: Office of Seafood, Food and Drug Administration. Superintendent of Documents. US Government Printing Office. d Froese, R., Pauly, D. (Eds.), 2003. Fish Base. Available at: www.fishbase.org (version 24 Oct 2003). e http://www.gsmfc.org f http://www.redlist.org/search/details.php?species=3850 g http://cdserver2.ru.ac.za/cd/011120_1/Aqua/SSA/onilo.htm h http://www.oceanbeauty.com/products/farm_atlantic.htm i http://www.geocities.com/scott_cotter/fish3.htm Abbreviations: aka, also known as; ND, no data. Source: Reproduced from Center for Food Safety and Applied Nutrition of the USA Food and Drug Administration; Food and Agricultural Organization of the United Nations.

a

Japanese amberjack by some sources)

55.0 cm ND ND 1.2 m 32.0 kg ND 1.5 m 40.0 kg ND

A. 1.3 m B. 26.3 kg C. 16 years

A. Anguilla japonica B. Japanese eel

A. Ictalurus punctatus B. Channel catfish

A. 1.2 m B. 25.4 kg C. 11 years

Rainbow trout are native to temperate, fresh, brackish and marine waters from Alaska to Mexico as well as waters of Asia (e.g., Eastern Russia). Rainbow trout have been disseminated worldwide (e.g., Africa, Asia, New Zealand, and South America) Fresh waters of moderate temperatures in Canada, Mexico, and USA

A. Oncorhynchus mykiss B. Rainbow trout

Species of Meat Animals | Finfish 341

342

Table 3

Species of Meat Animals | Finfish Average nutritional data per 100 g of raw tissue from selected finfish groupsa,b

Groupsc Water (g)

Energy (kJ)

Protein (g)

Total fat (g)

Calcium (mg)

Iron (mg)

Sodium (mg)

Ascorbic acid (mg)

Riboflavin (mg)

Niacin (mg)

Cholesterol (mg)

1 2 3 4

797.6 562.7 441.5 323.7

17.54 19.19 22.69 16.56

12.82 5.82 0.98 0.72

26.0 44.9 22.5 17.0

0.85 0.86 0.99 0.26

70.8 60.4 37.0 72.0

1.22 0.84 1.00 0.33

0.150 0.110 0.074 0.091

4.757 5.490 12.600 2.118

75.6 60.0 46.0 44.7

68.50 72.99 70.79 79.56

a

The raw data for this table were obtained from the United States Department of Agriculture, Agriculture Research Service, Nutrient Data Laboratory at http://www.nal.usda.gov/ fnic/foodcomp b Groups 1, 2, 3, and 4 had energy ranges of 858−766, 619−519, 452−431, and 343−289 kJ, respectively. c Group 1 consisted of Atlantic mackerel, Pacific herring, Greenland halibut, eel (mixed species) and Atlantic salmon (http://www.cfsan.fda.gov/Bfrf/rfe1at.html); group 2 contained milkfish (http://www.cfsan.fda.gov/Bfrf/rfe1ml.html), Spanish mackerel, rainbow trout, channel catfish, whitefish (mixed species), European anchovy, carp and bluefish; group 3 was made up of yellowfin tuna (http://www.cfsan.fda.gov/Bfrf/rfe1yn.html) and skipjack tuna; and group 4 was comprised of Atlantic cod, walleye pollock and orange roughy (http://www.cfsan.fda.gov/Bfrf/rfe1or.html).

obesity in developed countries such as USA. Further, some individuals may be concerned about consuming enough calcium for bones and iron for blood, whereas others may be interested in maintaining lower sodium intake to help decrease their potential for high blood pressure. The three vitamins were selected to show examples of those components that appeared to be important to consumers or to be significant in some fish flesh.

Processing of Finfish Finfish products can be processed fresh, frozen, cooked, precooked, smoked, cured, canned, etc. For example, finfish might be caught and immediately transported to the processing plant in tank trucks with water. Fish may be received live at the facility and may then be stunned, headed and gutted, and washed as needed. Afterwards, fish may be cut into fillets (with skin-on or skinless) followed by a liquid cooling step. Next, fillets might be inspected (e.g., for parasites or nematodes), cut and deboned, and evaluated for size or graded. The product can then be put into packing containers and the containers passed over scales to determine the weight and labeled. The last steps might involve chilling and storage at the plant before transporting the product for sale. Similarly, after fish have been harvested and frozen, fish can be shipped to a processing facility. At the plant, the fish can be received, thawed and examined, sorted, and passed like fresh fish through inspection. The fillets can then be individually quick frozen and glazed with water. The rest of the processing operation is as above, except that the product might be stored frozen before shipment to consumers. The first steps of smoking fish might approximate the above processes. After the fillet is produced, the tissue might be salted and then rinsed before being placed onto a metal rack for subsequent smoking (hot or cold). After smoking, the product should be cooled before further processing (e.g., coloring and slicing). Smoked product is packaged, frozen, etc. as in the earlier processes. Cured and salted fish might be processed as in the smoked fish operation except that it has a drying step rather than a smoking cycle. These cured and salted products might be stored refrigerated or dry. Additional fish processing operations (e.g., battered and breaded, precooked or cooked, canned, and modified

atmosphere packaged) are not covered here and the reader should refer to other articles in the Encyclopedia and to the Further Reading listed at the end of this article to learn more on these topics.

Potential Health Issues Associated with Finfish Finfish products are generally safe for human consumption. However, fish are animals and they might have parasites (e.g., anisakid nematodes) that can be killed by freezing or by cooking. In addition, they might contain toxins that are harmful to consumers. Subjection of scombroid species (e.g., mackerel and tuna) to improper handling and chilling after harvesting can result in histamine formation by bacteria and to consumers being afflicted with scombroid poisoning or histamine toxicity. Reef fish (e.g., barracuda and snapper) might consume toxic dinoflagellates. Subsequently, when humans consume the fish tissue they could become ill from ciguatoxin. Puffer fish might contain a tetrodotoxin, which can be fatal to consumers. Escolar is a fish that might cause consumers to have diarrhea due to gempylotoxin. Other health concerns include finfish that have been contaminated with chemicals such as heavy metals (e.g., methyl mercury), polychlorinated biphenyls , pesticides, drugs, etc. Despite the previous comments, it is important to emphasize that finfish products are safe for human consumption in the vast majority of cases and that potential risks can be prevented with adequate processing.

Welfare Issues Animal welfare has become increasingly important worldwide. A fundamental issue when deciding on moral duties of humans toward animals is whether they are capable of experiencing pain and other forms of suffering such as fear and distress. The welfare of fish has been much less studied than that of mammals and birds, and considerable debate with opposing views still exists on the ability of fish to suffer. The main argument used by those that deny that fish are capable of experiencing negative emotions including pain is that fish lack the extensive cerebral cortex of mammals. This argument,

Species of Meat Animals | Finfish

343

however, has several problems. First, it has been suggested that emotional responses might not depend on higher forms of consciousness, but on more basic ones. Second, a given function might be served by different brain structures in different animals, and the possibility exists, therefore, that brain structures other than the cortex might support emotional experiences in fish. In this context, it is particularly relevant that the dorsomedial part of the telencephalon of fish seems to be homologous to the mammalian amygdala, which is involved in arousal and emotion, particularly fear. Several criteria have been proposed to decide whether an animal is capable of experiencing pain. These criteria are as follows:

mammals. Chronic stress in fish, as in mammals, may have negative effects on health, for example, by impairing the immune function. Another similarity between fish and mammals is that both show individual differences in their stress response, some individuals adopting an active strategy and others a more reactive one. The Panel on Animal Health and Animal Welfare of the European Food Safety Authority concluded that “Fish possess a suite of adaptive behavioral and physiological responses that have evolved to cope with stressors. Many of these are homologous with those of other vertebrates…Prolonged exposure to stressors generally leads to maladaptive effects or chronic stress.”

1. Presence of functional nociceptors. 2. Presence of nervous pathways leading to higher brain structures. 3. Activation of brain structures during potentially harmful or injurious stimulation. 4. Presence of endogenous opioids and opioid receptors. 5. Suppression of responses to noxious stimuli by analgesics. 6. Changes in behavior (including avoidance behavior and inhibition of normal behavior) associated with noxious stimulation.

Nonfinfish

Current scientific evidence suggests that fish – or at least some fish species – meet all these criteria. For example, studies in rainbow trout (Oncorhynchus mykiss) have shown that there are nociceptors on the face of the trout and that they are innervated by the trigeminal nerve, which projects to the thalamus as in mammals. Opioids and opioid receptors equivalent to those found in mammals have been identified in fish brains. Studies in the goldfish (Carassius auratus) have shown that brain activity changes during noxious stimulation. Changes in behavior (including an increase in respiration rate, a decrease in feed intake, and a decrease of fear response to a novel stimulus, supporting the idea that pain dominates fish attention) have been described in rainbow trout associated with noxious stimulation, whereas these changes do not appear if fish are given analgesics. Taking all this evidence together, the Panel on Animal Health and Animal Welfare of the European Food Safety Authority concluded that “The balance of evidence indicates that some fish species have the capacity to experience pain. However research and developments in the area of cognition and brain imaging techniques should be carried out in fish to further our knowledge and understanding of pain perception.” Fear is another negative emotional experience with obvious effects on welfare. Fish show a variety of behavioral responses to threatening stimuli, including escaping and becoming motionless. Additionally, fish can learn to avoid threatening stimuli, suggesting that a cognitive process is involved in their fear response. A cognitive process is further supported by the analogy between the amygdala of mammals and the dorsomedial part of the telencephalon. The conclusion of the Panel on Animal Health and Animal Welfare of the European Food Safety Authority on fear in fish was that “Responses of fish, of some species and under certain situations, suggest that they are able to experience fear.” Stress physiology of fish has been studied over the past decades and has been shown to be similar to that of

By definition, sharks, skates, and rays, for example, were not included in the finfish category. Several species of these animals are marketed (e.g., fresh, frozen, dried/salted, and smoked) in interstate/intrastate commerce. Further, some species are utilized to produce fish meal, fish oil, liver oil, shark fin soup, drugs or medicines, leather from hides, etc.

Disclaimer The scientific, market, and common names identified in this document may or may not correspond with The Seafood List: FDA's Guide to Acceptable Market Names for Seafood Sold in Interstate Commerce 1993.

See also: Canning. Environmental Contaminants. Fish Inspection. Packaging: Modified and Controlled Atmosphere. Processing Equipment: Battering and Breading Equipment. Refrigeration and Freezing Technology: Applications; Equipment; Principles. Smoking: Liquid Smoke (Smoke Condensate) Application; Traditional. Species of Meat Animals: Shellfish

Further Reading Banister, K., Campbell, A., 1986. The Encyclopedia of Aquatic Life. New York: New York: Facts on File. pp. 3−4. Chandroo, K.P., Duncan, I.J.H., Moccia, R.D., 2004. Can fish suffer?: Perspectives on sentience, pain, fear and stress. Applied Animal Behaviour Science 86, 225–250. EFSA, 2009. Scientific Opinion of the Panel on Animal Health and Welfare on a request from European Commission on General approach to fish welfare and to the concept of sentience in fish. EFSA Journal 954, 1–26. FAO, 2000. FAO Yearbook, Fishery Statistics: Capture Production. 1998 Rome: Food and Agriculture Organization of the United Nations.vol. 86(1). FDA, 2001. Fish and Fisheries Products Hazards and Controls Guidance third ed. College Park, MD: Department of Health and Human Services, Public Health Service, Food and Drug Administration (FDA), Center for Food Safety and Applied Nutrition, Office of Seafood. Docket Number 93 N-0195. Froese, R., Pauly, D. (Eds.), 2003. Fish Base. Available at: www.fishbase.org (accessed 31.10.13). Fry Jr F.S., 2003. Personal communication. College Park, MD: Office of Seafood, Center for Food Science and Applied Nutrition, Food and Drug Administration. Martin, R.E., Carter, E.P., Flick, Jr, G.J., Davis, L.M., 2000. Marine and Freshwater Products Handbook. Lancaster, PA: Technomic Publishing.

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Species of Meat Animals | Finfish

Miller, P., 1980. Collins Handguide to the Fishes of Britain and Northern Europe London: William Collins. pp. 6−7. National Marine Fisheries Service, 1990. HACCP Regulatory Model for Raw Fish. Report of the Model Seafood Surveillance Project. Pascagoula, MS: National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Office of Trade and Industry Services, National Seafood Inspection Laboratory. National Marine Fisheries Service, 1991. HACCP Regulatory Model for Smoked and Cured Fish. Report of the Model Seafood Surveillance Project. Pascagoula, MS: National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Office of Trade and Industry Services, National Seafood Inspection Laboratory. Norman, J.R., 1963. Introductory. In: Greenwood, P.H. (Ed.), A History of Fishes, second ed. New York: Hill and Wang, pp. 1–5. Randolph S.C., 2003. Personal communication. College Park, MD, USA: Office of Seafood, Center for Food Science and Applied Nutrition, Food and Drug Administration.

Randolph, S., Synder, M., 1993. The Seafood List: FDA's Guide to Acceptable Market Names for Seafood Sold in Interstate Commerce 1993. Washington, DC: Office of Seafood, Food and Drug Administration. Superintendent of Documents. US Government Printing Office. Robins, C.R., Ray, G.C., 1986. A Field Guide to Atlantic Coast Fishes: North America (The Peterson Field Guide Series®). Boston, MA: Houghton Mifflin. Rohr B.A., 2003. Personal communication. Pascagoula, MS: Mississippi Laboratories, Southeast Fisheries Science Center. Rose, J.D., 2002. The neurobehavioral nature of fishes and the question of awareness and pain. Reviews In Fisheries Science 10, 1–38. Sanders Jr N., 2003. Personal communication. Pascagoula, MS: Mississippi Laboratories, Southeast Fisheries Science Center. Sneddon, L.U., 2006. Ethics and welfare: Pain perception in fish. Bulletin of the European Association of Fish Pathologists 26, 7–10.

Game and Exotic Animals LC Hoffman and D Cawthorn, Stellenbosch University, Matieland, South Africa r 2014 Elsevier Ltd. All rights reserved.

Glossary Antelope The term referring to a diverse group of eventoed ungulate species that is indigenous to various regions in Africa and Eurasia. Bushmeat The meat derived from wild animals that are hunted for subsistence or informal trade, most often illegally. Dressing percentage The percentage of an animal's live weight that becomes the carcass weight at slaughter, determined by dividing carcass weight by live weight and multiplying by 100. Farmed game Land animals and birds that are not conventionally regarded as domesticated but are bred and reared in captivity.

Introduction Species of wildlife or game may be harvested to obtain meat, fur, skins, feathers, antlers, horns, or trophies. In particular, the use of wild animals for food is as old as humankind itself and the meat remains an important food source for many people throughout the world. With the escalating demand for animal protein from domestic animals, coupled with the decreasing supply and the high prices associated with such products, it has become inevitable for many populations to turn to meat from the wild as an alternative, including game and other exotic animals. The conceptualization of a uniform definition for ‘game’ has been an issue of ongoing debate over the years and this differs widely in different parts of the world. Some sources define game as only those free-roaming land animals and birds that are hunted for food in their wild environment. According to such a definition, game meat is the result of the process of natural selection, rather than of human ‘production.’ Other sources, however, use the term to include both those land animals and birds – either wild or farmed – that are not generally considered to be domestic animals. The division of ‘large’ and ‘small’ game species is equally confounded, with the legal definitions of these, as well as their range and population levels, also varying from country to country. Since the production, distribution, veterinary inspection protocols, and public health risks differ vastly between wild, extensively farmed, and intensively farmed animals, it is important for concrete distinctions to be made between the latter groups. From a practical viewpoint, it might be preferable to consider ‘game’ as all animal and bird species that can be legally killed by hunting (recreational or commercial) and that will or may be subsequently used for human consumption. Alternatively, the term ‘wild game’ may be used for free-range animals/birds legally hunted in the wild, while ‘farmed game’ might be

Encyclopedia of Meat Sciences, Volume 3

Game birds A broad collection of birds, grouped into land fowls and waterfowls that are hunted for sport and food. Game meat Meat derived from land animals and birds that are legally hunted in the wild. Ungulate A mammal with hooves. Venison The term mainly used nowadays to refer to the meat from deer species. Wild game Free-ranging land animals and birds that are legally hunted in the wild for food. Zoonotic disease An animal disease that can be transmitted to humans.

applied to those not conventionally regarded as domesticated but are bred and reared in captivity. From a consumer perspective, it is also likely desirable to discriminate the meat of wild, free-roaming game from that of farmed species. Traditionally, the term ‘venison’ has been loosely applied around the world to describe the meat from any animal considered to be a game species. Although the English word ‘venison’ originated from the Latin venari (to hunt, pursue), today its use is largely restricted to the flesh from various cervid (deer) species, which are being increasingly farmed in the Northern Hemisphere for food. Some argue that these animals are becoming more domesticated in the sense that the farmer often decides which animals will be bred, what feed will be fed, and which animals will be slaughtered. For this reason, it is recommended that the term ‘game meat’ be exclusively used for the meat derived from animals/birds hunted in the wild (e.g., free-ranging antelope, wild boar, and game birds) and which can essentially be considered ‘natural’ or ‘organic.’ However, the term ‘venison’ should potentially be reserved for the meat from cervids, and perhaps also for that from other ‘farmed game’ species (in accordance with the aforementioned explanation) (e.g., rabbits and birds reared in captivity). Further, it is essential to define the term ‘bushmeat,’ which generally refers to the meat from wild animals that are hunted for subsistence or for the informal market, most often illegally. Although originally associated with primates, bushmeat also encompasses hippopotami, elephants, giraffe, zebra, antelope, water buffalo, wild cats, birds, reptiles, and rodents. The bushmeat trade is enormous in Africa and other developing third world countries, mainly as a consequence of rural poverty and the availability of external markets. This has not only resulted in the overexploitation and decline of a large number of wildlife species (many of which are protected by international wildlife legislation and treaties), but also poses a public health risk as these

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animals may harbor diseases and would not typically undergo veterinary inspections. One of the major drivers for the growing acceptability and consumption of game meat can be attributed to increasingly health-conscious modern consumers, as the aforementioned species are known to produce leaner meat compared to domestic livestock species. Another motivator for the increased demand lies with rising consumer concerns about the environment and there is thus the desire for organic products, as well as products produced by natural production (low-input systems) methods. There is also a new generation of younger consumers who wish to try new adventurous foods and many tourists to Africa wish to eat local wild species, ranging from springbok to crocodile as part of the ‘Africa experience.’ It is common to find game meat or venison on the menu of topclass restaurants throughout the major cities of the world. Furthermore, with the intercontinental immigration of diverse cultures and the fact that the world has become one large global village, many individuals are increasingly seeking access to their own traditional meats even when they are far from home. The farmed game animal industry has experienced unprecedented growth over the last few decades, largely reflecting the aforementioned consumer interests in lean and alternative food products. Species that are discussed in this article include various ungulates (farmed and wild species) and game birds, emphasizing carcass characteristics, nutritional composition, and palatability attributes. The distribution, population, and hunting methods will not be discussed in detail as this information can be found in various literature sources and is very species-specific. Bushmeat will not be covered in depth as many species that are traded illegally are also traded legally, and are thus covered in that specific section. Since fish are excluded from the term ‘game,’ these are not discussed further in this section (although some fish caught for sport are termed game fish).

Game Production, Consumption, and Economics Although it is extremely challenging to obtain reliable data relating to the extent of the global game meat trade, it is accepted that formal game production still constitutes a small share of the word's overall meat production. Africa, the two Americas, Oceania, and Europe are considered to be among the primary game producers. Records from the United Nations Food and Agriculture Organization Statistical Database (FAOSTAT) suggest that the total global game production in 2011 was more than 1 942 500 tons. The African countries that were reported to contribute substantially to the FAOSTAT figures included Nigeria (163 000 tons), Ghana (74 300 tons), South Africa (46 000 tons), and Kenya (25 100 tons). In addition, game production in 2011 in the United States (US) was estimated at 248 000 tons, whereas in the European Union (EU) this was in the order of 130 990 tons. However, it is unlikely that the magnitude of the illicit bushmeat trade was taken into account in the former calculations, neither the value of internal trade or direct sales by hunters to local consumers and establishments. In the Congo Basin alone, for instance,

the bushmeat harvest is expected to be upward of one million tons per year. In South Africa, more than 1 million animals (comprising approximately 35 different species) are harvested a year by recreational game hunters alone and the annual turnover from this industry is around ZAR 3 billion (1 ZAR = 0.095 USD (approx.)). The number of game slaughtered in Canada in 2012 exceeded 668 000 head and more than one million kg of game meat was exported from the country in the same year. With the exception of poor communities, game meat does not constitute a high proportion of the total meat consumed. The estimated annual per capita consumption of wild and farmed game meat in Austria, France, Germany, Poland, and Switzerland is 0.6–1.0 kg. Ungulates (e.g., deer, moose, and wild boar) contribute approximately 3.3 kg per capita per annum in Norway and 1–4 kg per capita per annum in Italy. Much of the game meat consumed is either from a personal hunt or from value-added products. These range from fermented and processed products adhering to first world standards in Europe to smoked dried meat in Africa.

Birds The ratites and game birds are among the most important meat-producing birds, being consumed and traded on markets across the globe. Their production systems are not described in this section as this has been done elsewhere. In terms of the ratites, the raising of ostriches for meat has become well established and has been commercially successful. The birds are generally slaughtered in highly sophisticated abattoirs with strict hygiene controls rather than being hunted in the wild. Attempts have also been made to raise the emu and rhea for commercial purposes, although this has been less effective due to their low yield and the lower market value of their meat and other products. Owing to the morphological structure of ratites – with most of the meat being found on the leg – they have a low lean meat yield (Table 1). Ratites have only small localized subcutaneous fat depots, normally above the legs and then a well-developed fat pad over the belly, posterior to the keel. The low intramuscular fat and favorable fatty acid profile has resulted in an increased global demand for ostrich meat over the past years (Table 1). The fatty acid profile of the birds has been shown to be influenced by the diet. Table 1 Summary of carcass yields and nutritional values of selected ratites Ostrich Bodyweight (kg) Carcass weight (%) Total lean meat (%) Trimmings (%) Moisture (%) Protein (%) Fat (%) Energy (kJ per 100 g) Cholesterol (mg per 100 g)

85 59 39 12 76.6 20.9 0.5 390 57

Emu 41 53 34 13 73.6 21.2 1.7–4.5 471–531 39–48

Rhea 25 61 36 14 74.8 22.9 1.2 439 57

Species of Meat Animals | Game and Exotic Animals Table 2

347

The mean weights (7standard deviation (sd)) of the major muscles from ostriches having live weights of 85–95 kg

Muscles

Mean weights (kg7sd) for muscles (n¼34)

Muscles expressed as mean percentage (%7sd) on a leg weight basis

M. M. M. M. M. M. M. M. M. M. M. M.

0.6970.10 0.2970.04 0.3070.04 0.5970.08 0.8470.13 0.4070.06 0.1970.03 0.1170.02 1.4170.15 0.4970.07 1.0870.15 0.5570.08

4.770.5 2.070.3 2.170.3 4.070.7 5.770.8 2.870.4 1.370.2 0.870.2 9.671.1 3.470.6 7.570.9 3.870.7

femorotibialis accessorius fibularis longus flexor cruris lateralis gastrocnemius pars externa gastrocnemius pars interna iliofemoralis iliofemoralis externus femorotibialis internus iliofibularis iliotibialis cranialis iliotibialis lateralis obturatorius medialis

The most commonly marketed meat is derived from the posterior limbs and includes whole muscle cuts such as the Musculus iliofibularis (fan fillet), M. iliofemoralis (side strip), M. iliotibialis cranalis, M. femorotibialis accessorius, M. fibularis longus, M. flexor cruris lateralis, M. obturatorius medialis, M. gastrocnemius (big drum), and M. iliotibialis lateralis (Table 2). Slight differences in the chemical composition and quality characteristics are found between the muscles within the ostrich carcass. Similar to other farmed livestock, the muscle composition is influenced by factors such as genetics, age, and diet. Gender has a smaller influence because most birds are slaughtered as they reach sexual maturity (10–14 months of age). In spite of the success of the ostrich industry, the international trade in ostrich meat has been negatively influenced by outbreaks of Avian influenza, which has forced large producers in Africa to explore other avenues for meat utilization. These have included promoting consumption locally and in neighboring countries, processing the meat into various valueadded products (Table 3), as well as employing a heat treatment to produce sous vide products that are exported. The expression ‘game bird’ describes a very broad collection of birds grouped into land fowls and waterfowls, including species in the following orders: Galliformes (including guinea fowls, partridges, quails, francolins, and pheasants), Anseriformes (including ducks and geese), Columbiformes (including doves and pigeons), Pterocliformes (including sandgrouse species), and Charadriiformes (including snipes). Game birds have long been hunted for recreational reasons, but their popularity as a food source is growing and these are now obtained from the wild, as well as being farmed. The game bird industry has developed into a multimillion dollar industry, particularly in the United States and European Union, and it is also emerging in South Africa, with its success being accompanied by the ongoing management and conservation of bird populations. In the United States, more than 38 million game birds are shot each year, many of which are destined for restaurants or these are marketed directly to consumers. In the United Kingdom, approximately 19 million game birds were shot in 2004 alone, of which the majority were also incorporated into the country's food chain.

Captive-bred birds are an integral part of the international industry, chiefly in Europe, where large numbers of game birds are bred annually for release into the wild. It is estimated that more than 20 million game birds (80% are pheasant and the rest are mainly red-legged partridge) are reared and released for hunting in the UK each year, with most of the hunted birds being consumed by the hunters, farmers, or beaters. Gray partridge and ducks are also reared for this purpose. The composition and quality of the meat from different game birds can vary quite substantially and is largely dependent on the diet of the birds. Some game birds closely resemble chicken and comprise mainly white meat, whereas others have a stronger ‘gamey’ flavor and can contain more dark meat. The proximate composition of selected game birds is shown in Table 4. In general, most game birds have a relatively low fat content, meaning they commonly need to be basted or larded before roasting. Wild birds are normally much leaner than the varieties reared in captivity. Older birds can be tougher and are usually best cooked with slow moist heat, or used in stews or soups. As wild game birds are normally hunted using shot guns, the possibility of lead residues in the muscle has raised some speculation and has been the subject of considerable research. Lead from ammunition in game meat is more bio-accessible after cooking, especially when using highly acidic recipes that include substances such as vinegar.

Deer Deer are ruminant mammals of the family Cervidae that can be found in the wild or kept in parks, but which are also increasingly being farmed both extensively and intensively in New Zealand and parts of the northern hemisphere. In particular, New Zealand (having the largest farmed deer population in the world) produced approximately 23 308 tons (carcass-weight equivalent) of venison between 2012 and 2013, of which around 95% was exported after processing. Nonetheless, the hunting of these species in the wild remains popular throughout Europe and North America. Fallow deer (Dama dama) and red deer (Cervus elaphus) are the most commonly farmed in Europe, whereas the elk or wapiti (Cervus

348

Table 3

Species of Meat Animals | Game and Exotic Animals The chemical composition of various processed ostrich products sold in retail outlets in South Africa

Chemical component (%)

French poloni

Ham

Bacon

Smoked Russian

Smoked Vienna

Smoked fillet

Dry mass Protein Fat Ash Cholesterol (mg per 100 g)

29.31 12.36 6.93 7.66 36.6

32.32 17.87 1.75 11.54 32.9

26.60 20.45 1.92 11.55 50.7

33.91 17.73 10.78 6.60 39.5

36.41 13.35 14.85 5.77 43.7

26.90 20.85 2.28 8.87 51.0

Fatty acids (% of total FA) C14:0 C16:0 C18:0 C20:0 C22:0 C24:0 SFA C16:1n7 C18:1n9 C20:1n9 C24:1n9 MUFA C18:2n6 C18:3n6 C18:3n3 C20:2n6 C20:3n6 C20:4n6 C20:3n3 C20:5n3 C22:2n6 C22:4n6 C22:5n3 C22:6n3 PUFA

0.60 25.79 7.94 0.11 0.01 0.01 34.46 5.61 37.60 0.33 0.04 43.58 15.91 0.06 4.47 0.17 0.08 0.84 0.06 0.11 0.00 0.10 0.14 0.06 22.00

1.38 21.97 12.65 0.12 0.00 0.00 36.11 2.97 46.65 0.09 0.00 49.70 8.20 0.25 1.98 0.00 0.19 2.23 0.12 0.56 0.00 0.00 0.37 0.30 14.18

1.30 27.65 10.20 0.20 0.08 0.35 39.78 5.03 28.95 0.00 0.00 33.97 14.78 0.72 2.90 0.13 0.20 5.64 0.00 0.90 0.00 0.46 0.42 0.10 26.25

1.69 27.30 12.53 0.22 0.00 0.00 41.74 2.96 44.61 0.16 0.00 47.73 7.94 0.06 1.63 0.00 0.00 0.43 0.00 0.00 0.00 0.48 0.00 0.00 10.53

0.67 24.31 8.36 0.21 0.02 0.02 33.59 5.50 43.04 0.28 0.27 49.09 12.92 0.04 3.36 0.19 0.11 0.53 0.00 0.06 0.00 0.05 0.06 0.00 17.32

0.86 19.84 13.38 0.15 0.11 0.11 34.44 3.80 32.22 0.21 0.19 36.41 17.99 0.06 2.28 0.22 0.55 5.63 0.00 1.08 0.00 0.46 0.43 0.43 29.15

Abbreviations: FA, fatty acids; MUFA, monounsaturated fatty acids; PUFA, polyunsaturated fatty acids; SFA, saturated fatty acids.

Table 4

Estimated proximate composition of the breast meat of selected game birds Guinea fowl

Moisture (%) Protein (%) Total fat (%) Ash (%)

Breast raw

Breast cooked

73.5 23.7 1.5 1.3

64.5 31.9 3.2 1.6

Egyptian goose Breast cooked

Francolin Breast raw

Quail Breast raw

Wild pheasant Breast raw

62.2 30.9 5.9 1.7

66.5 28.7 3.4 1.4

73.0 19.0 0.6 0.2

72.4 25.5 1.1 1.1

canadensis), fallow deer, sika deer (Cervus nippon), axis deer (Axis axis), and white-tailed deer (Odocoileus virginianus) are mainly farmed in the United States and Canada. The herding of reindeer is mostly carried out in the Nordic countries. Similar to farmed domestic livestock species (cattle and sheep), various factors can influence the carcass yield and lean yield of deer species (Table 5). Adult animals will have a lower bone yield than subadults due to the fact that bone matures earlier than muscle and fat. The lean yield in mule deer, elk (wapiti), and pronghorn antelope varies from as high as 78% to as low as 57% of the skinned carcass, depending on how the lean yield is calculated. Commercial lean yield percentages vary according to the skill with which the meat is trimmed off

the bone and the amount of fat and connective tissue trimmed. The lowest yields are normally obtained from the carcasses of hunted deer, as hunters seldom have the skill to trim efficiently and there is also lean meat lost due to bullet damage, fly strike, and spoilage. Venison consumption is particularly common in the United States, central Europe, and the United Kingdom. In general, consumers are drawn to its tenderness, low fat content (but favorable lipid composition), and high mineral levels (Table 6). Only very fat carcasses will have a visible subcutaneous fat layer. The same factors that influence the fatty acid composition of ruminants will influence the fatty acid composition of cervids (Table 7).

Species of Meat Animals | Game and Exotic Animals

African Ungulates The ecosystems of sub-Saharan Africa support a wide range of wild ungulate (hoofed animals) species, including more than 70 antelope species. Antelope not only signify a vital component of the fauna attracting game-viewing tourists and hunters, but they also provide a significant source of protein for human consumption. South Africa and Namibia are the two countries that have the most developed game meat industries in Africa. In these regions, wild ungulate species are often harvested using modern technologies and are processed according to strict EU regulations utilizing Standard Operating Procedures (SOPs) and Veterinary Procedural Notices (VPNs) to produce meat destined for the formal local and international meat trade. The game species harvested commercially are mainly the springbok (Antidorcas marsupialis; 480%), blesbok (Damaliscus pygargus phillipsi), and kudu (Tragelaphus strepsiceros), while the blue wildebeest (Connochaetes taurinus), impala (Aepyceros melampus), and gemsbok (Oryx gazella) are exported in smaller numbers. The duiker

Table 5 Lean, fat, and bone percentages in carcasses of some dissected Cervid species Species

Percentage Lean

Bone

Nilgai antelope Adult Subadult Fallow deer adult males

79.0 74.2 73.9

19.2 25.1 15.6

1.4 0.1 9.1

Red deer adult males Prerut Postrut

66.0 83.2

14.9 15.5

19.0 1.3

Mule deer adults Males Females

72.9 75.7

15.8 15.7

11.0 8.2

Elk (wapiti) adults Males Females

77.8 72.6

18.2 18.6

3.3 8.2

Pronghorn antelope adults Males Females

76.7 77.0

18.6 19.2

4.8 3.9

Table 6

Fat

349

species (subfamily Cephalophinae) are most commonly targeted in the bushmeat harvest and trade throughout Africa. A major problem faced by both these two countries as pertaining to the export of game meat is the prevalence of zoonotic diseases, particularly foot-and-mouth disease. In South Africa and Namibia, the endemic viral types are the Southern African Territories types of foot-and-mouth virus, SAT 1, 2, and 3. In contrast to farmed deer that are harvested in commercial abattoirs, the hunted ungulates are normally eviscerated in the field and dressed in informal to formal facilities. Most of the hunted species are hunted for recreational purposes and are consumed by the hunters or landowners and their immediate families. There have been some concerns about the consumption of meat that might contain residual lead (from the bullets) although it would seem as if the levels in the muscle are low. The dress out percentages of game meat species differ due to the influence of similar factors (age, gender, etc.) that influences the yield in other domestic species (Table 8). However, where males have horns and females have none, the former will have a lower yield. Most game species have no subcutaneous fat layer with the exception of the zebra, which has a very thick subcutaneous fat cover. Although reliable information on the proximate composition of many African ungulate species is limited in the scientific literature, that which is available indicates that the meat from these species can be considered highly nutritious and a valuable source of protein (Table 9). The meat also has a low fat content (generally o2.5%, with the exception of blesbok), with desirable ratios of polyunsaturated fatty acids (PUFA) to saturated fatty acids (SFA), as well as omega-6 to omega-3 fatty acid ratios. The fatty acid composition of game meat is like most ruminants, influenced to a lesser extent by the diet. Nonetheless, game species can be divided into grazers that only consume grass, mixed feeders that consume both grass and browse, and the browsers. The impala (Aepyceros melampus) is a mixed feeder and will consume the more dominant feed type found in the region, which leads to slight differences in the fatty acid profile of muscle (Table 10).

Wild Suids This section discusses various wild Suid species (wild boar, warthog, and bushpig), but will not focus on feral pigs (escaped domestic pigs).

Nutrient composition of meat derived from wild animals (amounts in 100 g raw meat)

Species

Energy (kJ)

Protein (g)

Fat

SFA (g)

MUFA (g)

PUFA (g)

Cholesterol (mg)

Iron (mg)

Pronghorn antelope Caribou Deer Elk (wapiti) Moose Range-grazed beef

477 531 502 464 427 469

22.4 22.6 22.9 22.9 22.4 21.8

2.0 3.4 2.4 1.4 0.7 2.4

0.74 1.29 0.95 0.53 0.22 0.93

0.48 1.01 0.67 0.36 0.15 0.75

0.44 0.47 0.47 0.30 0.24 0.19

52 83 54 48 59 49

3.2 4.7 3.4 2.8 3.2 2.2

Abbreviations: MUFA, monounsaturated fatty acids; PUFA, polyunsaturated fatty acids; SFA, saturated fatty acids.

350

Species of Meat Animals | Game and Exotic Animals

Table 7 Mean values for fatty acid composition (g per kg total fatty acids) in M. longissimus from pasture and pellet-fed reindeer (Rangifer tarandus tarandus L.) and red deer (Cervus elaphus) Fatty acid

Polar lipids 14:0 16:0 16:1 17:0 17:1 18:0 18:1 18:1 (trans) 18:1 (n-9) 18:1 (n-7) 18:2 (n-6) 18:3 (n-3) 20:3 (n-3) 20:4 (n-6) 20:5 (n-3) 22:4 (n-6) 22:5 (n-3) 22:6 (n-3) SFA MUFA PUFA (n-6) PUFA (n-3) (n-6)/(n-3) Neutral lipids 12:0 14:0 14:1 15:1 16:0 16:1 (trans) 16:1 17:0 18:0 18:1 18:1 (trans) 18:1 (n-9) 18:1 (n-7) 18:2 (n-6) 18:3 (n-3) 20:0 20:3 (n-3) 20:4 (n-6) 20:5 (n-3) 22:5 (n-3) SFA MUFA PUFA (n-6) PUFA (n-3) (n-6)/(n-3)

Reindeer Pasture (n¼9)

Pellets (n¼ 6)

Degree of significance#

2.1 12.6 0.6 0.4 0.4 12.4 3.4 0.4 11.5 1.0 21.1 6.1 600 10.2 2.7 6.0 4.6 2.0 25.4 17.3 31.9 14.2 2.2

2.9 13.8 0.9 0.2 0.2 13.4 2.0 0.3 12.0 1.7 27.6 1.2 8.0 9.5 1.6 6.0 3.3 2.0 26.3 16.0 39.4 7.5 0.53

n.s. n.s ** *** *** * *** ** n.s *** *** *** *** n.s *** n.s. *** * n.s. * *** *** ***

4.5 1.7

3.5 1.8

** n.s.

23.8 0.3 0.9 1.0 21.4

27.2 0.3 1.6 0.8 21.0

*** n.s. *** *** n.s.

1.3 34.1 1.0 2.2 1.0 0.5

0.6 35.6 1.1 2.1 0.2 0.2

*** * * n.s. *** ***

0.4

0.2

***

4.0 53.0 37.6 2.6 1.4 1.9

0.1 54.6 39.2 2.3 0.3 7.7

*** n.s. * n.s. *** ***

Pellets (n¼7)

Degree of significance#

10.1 1.1

10.3 0.4

n.s. **

15.8 12.3

14.1 12.4

* n.s.

20.3 5.2 1.0 9.0 3.0

29.8 0.2 1.3 12.1 0.8

*** *** *** *** ***

4.0 0.9 25.9 13.8 29.3 14.2 2.1

1.9 0.2 24.4 12.4 41.9 4.5 9.3

*** *** n.s. n.s. *** *** ***

5.0 1.6 0 33.3

6.1 2.2 0.1 34.6

n.s. n.s. n.s.

9.3 0.6 15.7 24.7

11.9 0.4 9.3 25.7

* n.s. *** n.s.

3.8 1.5 0.1 0 0.7 0.3 0.6 54.7 36.4 4.3 2.5 1.7

5.3 0.3 0.1 0.1 0.8 0 0.2 50.6 39.8 6.6 0.6 11.0

Red deer Pasture (n¼7) Polar lipids

Neutral lipids

*** n.s. * n.s. *** *** ** ** *** ***

Note:# n.s., Not significant, *po .05, **po.01, ***po.001. Abbreviations: FA, fatty acids; MUFA, monounsaturated fatty acids; PUFA, polyunsaturated fatty acids; SFA, saturated fatty acids.

Wild boar, belonging to the genus Sus and pig family (Suidae), is regarded as the wild ancestor of the domestic pig. The species is native to many parts of Central and Northern Europe, the Mediterranean and Asia, but has also been introduced into some regions (notably Australasia and the

Americas). Although long valued for food and recreational hunting, the animals have also come to be regarded as agricultural pests and a threat to the ecosystem. The recent widespread intensifying of wild boar densities has stimulated interest in the animals as meat producers and also as a

Species of Meat Animals | Game and Exotic Animals Table 8 Namibia

351

Mean carcass yields (7standard errors) and least significant differences (LSD) for different gender and age groups of springbok from

Live weight (kg) Carcass weight (kg) Dressing (%)

Adult Male (n¼12)

Subadult Male (n¼7)

Adult Female (n¼11)

Subadult Female (n¼9)

40.44a71.883 24.72a71.145 61.6a71.36

34.94b72.249 19.73bc71.188 56.0b72.60

36.61ab70.495 21.25b70.416 58.1ab71.31

29.32c71.627 16.80c71.140 57.1ab71.18

LSD (p¼0.05) 4.571 9.341 4.539

Values in the same row with different superscripts differ significantly (p ¼.05).

a,b,c

Table 9 cervids

Proximate composition (g per 100 g wet weight basis) of the raw meat of some wild antelope species compared to that derived from

Animal species

Ungulates, Cervidae Red deer Fallow deer Roe deer Reindeer

Cervus elaphus Dama dama Capreolus capreolus Rangifer tarandus

Ungulates, African species Springbok Antidorcas marsupialis Blesbok Damaliscus dorcas phillipsi Kudu Tragelaphus strepsiceros Impala Aepyceros melampu Red hartebeest Alcelaphus buselaphus caama Oryx Oryx beisa Duiker Sylvicapra grimmia

Sample analyzed

n

Moisture (g per 100 g)

Protein (g per 100 g)

Fat (g per 100 g)

Ash (g per 100 g)

M. M. M. M.

dorsi dorsi dorsi dorsi

10 10 10 11

76.90 74.90 74.80 71.80

21.70 22.00 23.00 23.60

0.60 2.50 1.70 2.80

1.11 1.08 1.15 1.10

Whole 9th-10th-11th rib cut Whole 9th-10th-11th rib cut M. longissimus dorsi

5

75.30

17.40

2.50

4.20

4

71.10

19.30

4.60

4.00

7

75.66

22.77

1.48

1.22

M. longissimus dorsi M. longissimus dorsi

11 13

74.96 75.00

22.63 23.30

2.06 0.60

1.22 1.20

Loin muscle M. longissimus dorsi

2 10

76.60 71.40

20.30 25.70

0.20 2.12

1.10 1.29

longissimus longissimus longissimus longissimus

potential farmed species. Today, the wild boar is propagated in Canada, Japan, the United States, and the Americas. Dressed weights (assumed to include the heads) for 3- to 4year-old hunted wild boar have been reported to be 65–108 kg for males and 50–80 kg for females. The carcass yields of animals hunted in Poland varied from 59% to 74% (the skin contributed B16–29% of initial weight), and increased with bodyweight. Yields of 81–83% have, however, been reported for adult and medium-sized boars hunted in Croatia and Italy, respectively. In comparison to the domestic pig, wild boar exhibits more carcass fatness and larger loin areas, while having darker, leaner, and less tender meat. The mean proximate composition of wild boar hunted in Italy was described as approximately 70.5% moisture, 25.9% protein, 1.5% fat, and 1.2% ash. Although the flavor and fatty acid composition of the wild boar may be affected by the gender and age of the animals, this is also largely influenced by the diet provided (as with other monogastric animals). The latter is largely evidenced in the depot fat of the wild boar, where unlike ruminants, the double bonds of fatty acids do not become hydrogenated during the process of digestion. An example of the fatty acid profile of hunted wild boar is shown in

Table 11. The ratio of PUFA:SFA in wild boar is estimated at 0.52–0.6. The warthog (Phacochoerus africanus) is a further wild member of the Suidae that has a natural distribution in the grasslands, savannah, and woodlands of sub-Saharan Africa. The species is characterized by a high fecundity (having 4–5 piglets per litter, gestation period of 167–175 days) and is frequently regarded as an agricultural pest in many farming regions. The meat has been consumed by locals in South Africa for many years and it is also being increasingly sought by tourists visiting the country's restaurants as part of a novel, uniquely African culinary experience. Recent research has focused on obtaining an enhanced understanding of the chemical composition of the meat, the development of value-added products and the promotion of its consumption based on its health and exotic qualities, with all these activities aimed at providing incentives for better management of growing warthog populations. Mature warthogs can attain body weights of 100 kg in males and 70 kg in the females. The dressing percentage is in the order of 52%, which is somewhat lower than domestic pigs. However, in contrast to domestic pigs, carcass weight in

352

Species of Meat Animals | Game and Exotic Animals

Table 10 Fatty acid (%)

C14:0 C16:0 C18:0 C20:0 C22:0 C24:0 SFA C16:1n7 C18:1n9 C20:1n9 C24:1n9 MUFA C18:2n6 C18:3n6 C18:3n3 C20:2n6 C20:3n6 C20:4n6 C20:3n3 C20:5n3 C22:2n6 C22:4n6 C22:5n3 C22:6n3 PUFA

Fatty acid profile (Mean7SE) of the longissimus dorsi muscle of impala from Mara and Musina Mara (grass diet)

Musina (grass and browse diet)

Females (n¼ 16)

Males (n¼24)

Females (n¼13)

Males (n¼15)

0.3970.41 20.72a74.27 22.0772.16 0.1170.04 0.09a70.06 0.1570.07 43.55a74.96 0.6170.46 21.81a75.81 0.13a70.23 0.1170.15 22.66a76.08 16.16a74.69 0.2070.19 4.36a71.39 0.1570.06 0.6970.26 6.12a72.00 0.0670.04 2.7671.37 0.08a70.07 0.4170.55 2.0270.87 0.7770.36 33.79a710.06

0.3270.77 15.04b75.55 22.2573.86 0.1470.08 0.16b70.12 0.1970.09 38.11b75.27 0.5770.33 19.34a74.80 0.10a70.04 0.1470.08 20.15a75.02 19.67b73.62 0.1470.03 5.09a71.11 0.1870.04 0.8670.23 7.87b71.67 0.0970.05 3.4470.84 0.14b70.07 0.4370.42 2.8270.78 1.0070.64 41.74b77.02

0.3070.36 22.47a73.71 21.9474.35 0.1370.06 0.16b70.10 0.1470.07 45.13a77.16 0.6770.33 19.06ab73.72 0.07b70.02 0.0970.07 19.89ab73.72 18.34a75.22 0.1370.05 4.01ab71.41 0.1370.04 0.7570.33 5.87a72.47 0.0670.04 2.4171.02 0.08a70.06 0.2270.08 2.2970.90 0.6970.34 34.98a710.22

0.5870.96 19.83a73.43 20.3572.92 0.1070.06 0.19c70.12 0.1970.10 41.26a75.87 0.6670.20 15.98b74.77 0.07b70.04 0.1070.11 16.80b74.87 22.74b75.74 0.1370.04 3.95b70.70 0.1570.06 0.9670.28 7.79b72.69 0.0670.05 2.7871.20 0.14b70.12 0.2470.17 2.4371.17 0.5670.45 41.94b710.31

a,b,c

Means in the same row with different superscripts differ significantly (po.05). Abbreviations: FA, fatty acids; MUFA, monounsaturated fatty acids; PUFA, polyunsaturated fatty acids; SFA, saturated fatty acids.

warthogs does not normally include the head, skin, and adjacent subcutaneous fat layers, which can largely account for the aforementioned factor. In warthogs, the contribution of the shoulder (37%), hind legs (32%), belly (14%), back (9%), and loin (7%) to the cold carcass weight also differs from that obtained from domestic pigs. Findings relating to meat quality characteristics suggest that warthogs are prone to develop pale, soft, and exudative (PSE) meat when exposed to ante mortem stress, which is a similar phenomenon seen in domestic pigs under comparable conditions. Warthog meat is of a high nutritional value and has a favorable fatty acid profile (Table 12), although the latter can be influenced by the diet as with the wild boar. The ratio of PUFA to SFA is approximately 1.33 (compared to 0.46–0.64 in domestic pigs), which is well above the minimum level of 0.4–0.5 recommended to be appropriate for human health. The bushpig (Potamochoerus larvatus) is a nocturnal wild pig species found in woodlands, forests, riverine vegetation, and reed beds in parts of East and Southern Africa. Similar to the warthog, many farmers in these regions consider the bush pig as a problem animal, as it thrives on many agricultural products and unearths root crops in their masses. In spite of this, the meat of the bushpig is still relished as a delicacy. Nonetheless, there is currently little available data on its quality and composition characteristics.

Kangaroos Kangaroos are marsupial species of family Macropodidae that are endemic to Australia, the meat from which has been consumed by the aboriginal inhabitants of this region for tens of thousands of years. Certain kangaroo species are abundant in rural Australia, being considered pests in some regions. Thus, the commercial harvest of these species from the wild is permitted in a number of Australian states, although this is under regulatory control. The red kangaroo (Macropus rufus), western gray kangaroo (M. fuliginosus), and eastern gray kangaroo (M. giganteus) comprise approximately 90% of the commercial harvest. Although 70% of the Australian kangaroo harvest is currently exported, the meat also has a niche market in Australia and is sold in both restaurants and retail outlets. Kangaroo meat has a strong flavor, is high in protein, as well as iron and zinc. The total fat content ranges from 0.2 to 1.4%, depending on the species. This consists of approximately 32% SFA, 31% monounsaturated fatty acids (MUFA), and 38% PUFA. The major SFAs in the meat include palmitic and stearic acids, whereas oleic acid is the predominant of the MUFA. The main PUFA include linoleic acid, arachidonic acid, and α-linolenic acid, respectively. The cholesterol levels are low and range from 41.6 to 65.3 mg per 100 g (depending on species, geographical origin, and cut) and the meat has a favorable omega6:omega-3 fatty acid ratio of 2.5:1.

Species of Meat Animals | Game and Exotic Animals Table 11

353

The lipid, cholesterol, and fatty acid profile of M. psoas major from wild boar hunted in Portugal Adult males (n¼6)

Adult females (n¼10)

Youngster (n¼ 9)

Carcass weight (kg) Lipid (g per 100 g meat) Cholesterol (mg per 100 g meat)

51 4.75 58.7

43 4.55 55.6

17 4.68 57.1

Fatty acid (% of total FA) C14:0 C16:0 C16:1 cis-9 C17:0 C17:1 cis-9 C18:0 C18:1 trans C18:1 cis-9 C18:2 n-6 C18:2 cis-9 trans 11 C18:3 n-3 C20:0 C20:2 n-6 C20:3 n-6 C20:4 n-6 C20:5 n-3 SFA cis-MUFA n-6 n-3 PUFA PUFA/SFA n-6/n-3

1.0 20.7 2.3 0.2 0.1 11.5 0.4 36.1 18.8 0.2 1.0 0.1 0.4 0.5 4.4 0.4 34.7 38.9 24.0 1.4 25.4 0.6 17.0

1 20.7 2.2 0.2 0.1 10.5 0.4 39.7 15.9 0.2 0.9 0.2 0.4 0.4 4.5 0.4 34.2 42.6 21.1 1.4 22.5 0.52 15.5

0.9 20.4 1.9 0.3 0.1 10.4 0.4 39.6 16.4 0.2 1 0.1 0.4 0.4 4.9 0.7 33.3 42.2 22.1 1.7 23.8 0.55 12.8

Abbreviations: MUFA, monounsaturated fatty acids; PUFA, polyunsaturated fatty acids; SFA, saturated fatty acids.

Rabbits and Hares Rabbits and hares are plentiful in many regions of the world and these are included in the diets of many populations. More than 60 species are documented within the Leporidae family. All hare species belong to the genus Lepus and rabbits belong to eight different genera. Native rabbit and hare species occur throughout Africa, America, Asia, and Europe. Man has used rabbits as food since 1500 BC. Today, these species can be hunted in the wild for consumption, but they are most commonly bred for meat in many parts of the world, including the United States, several European countries, Africa, and China. Rabbit breeding is particularly recognized to have potential for supplying high-value protein and for improving food security in the developing world. Since rabbits can adapt to diverse environmental conditions, have high reproductive and growth rates, as well as good feed conversion efficiencies, they are considered favorable meat producers. The Californian and New Zealand White are leading commercial breeds, with high ratios of muscle for their size. Fresh rabbit meat is sold in butcheries and markets in certain countries, while some supermarkets also sell frozen rabbit meat. Recent reviews on rabbit meat composition have confirmed that this is of high nutritional value compared to meat from other domestic animals. Rabbit meat is very palatable and is rich in high-biological value protein (B20–22%) and bioavailable micronutrients. It is generally low in calories, fat (although this varies according to the cut) and cholesterol. The leanest cut is usually the loin (1.8% fat), whilst the foreleg is

the fattiest cut (8.8% fat). The meat from wild rabbits is normally leaner than that from their domesticated counterparts, with mean total fat values of 1.05% and 5.55% in the respective animals. As rabbits are monogastric animals, the fatty acid composition of their meat is strongly influenced by the diet consumed, thus the PUFA content could be increased by supplementing diets with vegetable oils, such as linseed and rapeseed oil, or with fish oil. In rabbit meat, unsaturated fatty acids represent approximately 60% of the total fatty acids and the PUFA comprise approximately 32.5% thereof.

Bison Although bison (Bison bison) was previously nearly hunted to extinction, this species is now farmed successfully in Canada and America. The farmed bison population in Alberta, Canada is estimated at 490 000 head, while approximately 500 000 plains bison are said to exist in all of North America. It is calculated that 96% of the animals are selected for anthropogenic commodity production and less than 4% of the herds are managed for conservation purposes. Canada harvests just under 20 000 bison per annum. Factors influencing the carcass characteristics are similar to those observed for cattle, such as the females tend to gain fat earlier than males and there is an increase in meat toughness with age. In many instances, bison meat has been promoted to a niche market as a product with a strong heritage, unique flavor, dark red color and that is a healthy and nutritious red

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Table 12 Means and standard deviations (SD) of the proximate and fatty acid components of warthog loins (n ¼5) Component

% Mean

SD

Moisture Total lipid Protein Ash

74.04 1.69 22.14 1.29

0.94 1.39 0.30 0.03

Fatty acids C14:0 C16:0 C18:0 C20:0 C22:0 C24:0 Total SFA C16:1n7 C18:1n9 C20:1n9 C24:1n9 Total MUFA C18:2n6 C18:3n6 C18:3n3 C20:2n6 C20:3n6 C20:4n6 C20:3n3 C20:5n3 C22:2n6 C22:4n6 C22:3n3 C22:5n3 C22:6n3 Total PUFA

0.75 19.95 14.68 0.14 0.13 0.10 35.75 0.74 15.79 0.07 0.10 16.70 26.12 0.17 7.26 0.30 1.06 7.48 0.94 0.91 0.07 0.40 0.00 2.44 0.42 47.56

0.66 2.25 2.96 0.02 0.05 0.09 3.01 0.76 11.23 0.06 0.19 12.10 9.64 0.05 7.97 0.02 0.60 4.94 0.35 0.60 0.16 0.37 0.00 2.01 0.35 10.35

Abbreviations: MUFA, monounsaturated fatty acids; PUFA, polyunsaturated fatty acids, SFA, saturated fatty acids.

meat alternative. Most bison cuts have a protein content that varies from 21.0 to 23.0%. The total fat content of the meat is approximately 1.0–4.6% (depending on the cut), consisting of 0.4–1.3% saturated fat, 0.5–1.5% monounsaturated fat, and 0.1–0.2% polyunsaturated fat. The cholesterol levels found in bison muscles also varies from 25.7 to 48.3 mg per 100 g, values similar to those of other red meat species, when factors such as intrinsic variation between muscle groups, gender as well as analytical methodology is taken into account.

Camelids Camelids of the family Camelidae comprise the genera Camelus (including true camel species), Lama (including guanaco and Ilama), and Vicugna (including alpaca and vicuña), although the term ‘camel’ is normally used broadly to refer to all of these camel-like animals. Within the true camel species, the one-humped dromedary (Camelus dromedarius) accounts for up to 90% of all the camels

found, whereas the two-humped Bactrian camel (Camelus bacterium) represents the remainder. Approximately 80% of the world's camels are found in Africa, with Northeast Africa having the largest population of dromedaries. The average slaughter weight of mature, fattened desert camels is around 450 kg. The dromedary (Camelus dromedarius) dresses out at approximately 56% of live body and 64% of empty bodyweight, yielding 56% meat, 19% bone, and 13.7% fat. Fat partitioning differs between different body sites of the camel carcass and its distribution is quite unique when compared to other animals. The largest proportion of the camel's fat reserves occur in the hump (B30%), which accounts for up to 5% of live weight and 8% of carcass weight. A significant fat depot also exists on the abdominal floor. In 2009, the total world camel meat production amounted to over 360 000 ton, with Saudia Arabia, Sudan, Somalia, and Egypt being among the primary producers. Camel meat is often valued in harsh, dry environments where beef is in low supply and is popular throughout the Muslim world, in parts of Africa, Australia, and China. It is, however, noteworthy that some taboos exist with regards to camel meat consumption in certain cultures and religions. For instance, camel meat is seldom eaten in Europe and North America and its consumption is prohibited in the Torah for practicing Jews, for the Raikes or Rabaris of India, and for Ethiopian Christians. Camel meat is raspberry red to dark brown in color and is considered to be healthy compared to meat from many other animals. Compared to the meat from domestic livestock species, camel meat has a low fat content, higher moisture content, and similar protein content (Table 13). The hump frequently forms part of the sirloin cut and can result in the latter having high lipid content. The ratio of essential amino acids to nonessential amino acids is approximately 0.85, similar to the 0.86 reported for beef, 0.83 for lamb, and 0.90 for goat. Camel meat also has a similar mineral profile compared to domestic livestock, although it might have slightly higher sodium levels. The cholesterol content of the meat is believed to increase with the age of the camel (135 mg per 100 g fresh weight for 8 months old compared to 150 mg per 100 g fresh weight for 26-month-old animals). Of the genera Lama and Vicugna, the llama (Lama glama) and alpaca (Vicugna pacos) are domesticated. The guanaco (Lama guanicoe) and vicuña (Vicugna vicugna), however, are wild, and commercial farming of the latter two remains limited. The llama is produced for both its meat and fiber, while alpaca are primarily farmed for their fiber. Male llamas generally have slightly heavier dressing percentages (approximately 56%) than females (B54%). The meat from llama appears to represent a nutritious food source, providing high levels of protein (423%) compared with the values derived from most common domesticated animal species and fat content (0.5%) that is generally less than the latter. The fat content of guanaco meat is slightly greater than that of llamas and alpacas, but still less than that in the meat of domesticated species. A comparison of the fatty acid composition of camels and llama is depicted in Table 14. Both species have C16:0 as the dominant SFA, whilst llama has nearly twice as much C18:1 (the dominant MUFA) compared to camels.

Species of Meat Animals | Game and Exotic Animals Table 13

The proximate composition (g per 100 g wet weight basis) of the raw meat of camelids compared with domestic livestock species

Animal species

Ungulates, Camelids Camel Llama

Camelus dromedarius Lama glama

Alpaca Guanaco

Vicugna pacos Lama guanicoe

Domesticated species Beef Bos spp. Beef

Bos spp.

Lamb

Ovis aries

Mutton

Ovis aries

Goat Domestic pig

Capra hircus Sus scrofa domesticus

Sample analyzed

n

Moisture (g per 100 g)

Protein (g per 100 g)

Fat (g per 100 g)

Ash (g per 100 g)

Supraspinatus muscle Longissimus thoracis et lumborum

52

75.60

21.70

1.42

1.20

20

73.90

23.10

0.50

2.40

40 70

73.60 73.90

23.30 20.90

0.50 1.00

2.50 1.10

3

74.84

20.83

1.61

1.04

3

67.01

19.22

9.78

0.92

12

71.53

18.27

9.03

2.88

3

73.83

20.43

8.98

1.19

30 10

75.99 75.51

18 21.79

2.51 2.02

1.38 0.99

M. longissimus dorsi, without fat M. longissimus dorsi, with fat Mean of shoulder, leg, and loin Mean of shoulder, leg, and loin Muscle M. longissimus dorsi muscle

Table 14 Fatty acid composition (% of total fatty acids) of meat from different camelids Fatty acid Lipid (g per 100 g)

Camela

Llamab

1.52

3.5

Saturated 14:0 15:0 16:0 17:0 18:0 20:0 Total

7.7 1.7 26.0 1.5 8.6 * 51.5

4.1 – 24.8 – 21.5 – 50.3

Monounsaturated 14:1 16:1 17:1 18:1 20:1 Total

1.0 8.1 0.9 18.9 * 29.9

– 5.4 – 35.8 1.3 42.5

Polyunsaturated 18:2 18:3 20:2 20:3 20:4 20:5 22:4 22:5 22:6 Total P/S

12.1 0.5 0.1 0.3 2.8 0.3 0.1 0.5 0.1 18.6 0.36

3.1 0.8 – – 1.8 – – – – 7.2 0.14

a

Biceps femoris, seven 1- to 3-year-old males. Longissimus thoracis and lumborum, twenty 25-month-old males. Note: −, not shown; *, Trace (o0.1%) or undetectable amount. b

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Buffalo Water buffalo, belonging to the family Bovidae, are believed to number approximately 158 million in the world, and are important livestock species mainly in tropical and subtropical parts of Asia, as well as in South America, southern Europe, and northern Africa. The classification of water buffalo remains uncertain, with some authorities listing a single species, Bubalus bubalis, with three subspecies: the river buffalo (Bu. Bubalis bubalis), the swamp buffalo or carabao (Bu. bubalis carabanesis), and the wild water buffalo or arni (Bu. bubalis arnee). Other authorities believe that these are closely related; however, they are separate species. In 2003, the International Commission on Zoological Nomenclature ruled in favor of classifying wild buffalo as a separate taxon; consequently wild forms are now frequently referred to as Bu. arnee and domestic forms as Bu. bubalis. Water buffalo are normally slaughtered as spent animals or for meat production at approximately 18 months of age at 300–360 kg live weight and dress out at approximately 55%. The carcass yields of water buffalo are lower than that of cattle due to a heavier head (from the horns) and skin weights. Buffalo also tend to have a thinner subcutaneous fat layer than cattle, even when reared under comparable feedlot conditions. The meat accounts for approximately 22% of total meat produced in India, where it is gaining in popularity and there are no taboos against its consumption. There are thus opportunities for the development of the buffalo meat industry to cater for the needs of the domestic markets. Water buffalo meat is also known as carabeef or carabao meat and various value-added products including dried jerky, hamburger patties, bacon, and ham have been made from the meat of this species.

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Buffalo exhibit similar meat quality characteristics as cattle as pertaining to extrinsic and intrinsic effects such as age, gender, and muscle type. The meat of the former is darker than the latter, with the myoglobin content varying from 2.7 to 9.4 mg g1 depending on the type of the muscle and age. Water buffalo meat becomes darker with increasing age. It has been suggested that buffalo meat (lean) does not have any peculiar flavors and is organoleptically virtually indistinguishable from beef. Nonetheless, a consumer meat preference survey has indicated that 55.9% of the human subjects involved selected the beef, while 44.1% preferred carabeef. The color and amount of fat on the outside of the beef sample were primary responsible for buyer preference. Crude protein, ash, fat, cholesterol, myofibrillar, sarcoplasmic and insoluble protein contents of beef and carabeef are similar. Water holding capacity, pH, muscle fiber diameter, tenderness, firmness, and marbling scores in carabeef are also comparable to beef.

See also: Meat, Animal, Poultry and Fish Production and Management: Exotic and other Species. Parasites Present in Meat and Viscera of Land Farmed Animals. Slaughter-Line Operation: Other Species. Species of Meat Animals: Meat Animals, Origin and Domestication

Further Reading Beilken, S., Tume, R., 2008. Nutritional Composition of Kangaroo Meat. Barton, ACT: RIRDC, pp. 1−30. Dalle Zotte, A., 2002. Perception of rabbit meat quality and major factors influencing the rabbit carcass and meat quality. Livestock Production Science 75, 11–32. Dalle Zotte, A., Szendro˝, Z., 2011. The role of rabbit meat as functional food. Meat Science 88, 319–331. Geldenhuys, G., Hoffman, L.C., Muller, N., 2013. Aspects of the nutritional value of cooked Egyptian goose (Alopochen aegyptiacus) meat compared with other wellknown fowl species. Poultry Science 92, 3050–3059. Hoffman, L.C., Cawthorn, D.M., 2012. What is the role and contribution of meat from wildlife in providing high quality protein for consumption? Animal Frontiers 2, 40–53.

Hoffman, L.C., Sales, J., 2007. Physical and chemical quality characteristics of warthog (Phacochoerus aethiopicus) meat. Livestock Research for Rural Development 19. Available at: http://www.cipav.org.co/lrrd/lrrd19/10/hoff19153. htm (accessed 09.01.13). Hoffman, L.C., Wiklund, E., 2006. Game and venison − meat for the modern consumer. Meat Science 74, 197–208. Kadim, I.T., Mahgoub, O., Faye, B., Farouk, M., 2013. Camel Meat and Meat Products. Oxfordshire, UK: CABI, pp. 1−248. Lecocq, Y., 1997. A European perspective on wild game meat and public health. Revue Scientifique et Technique (International Office of Epizootics) 16, 579–585. Mead, G.C., 2004. Poultry Meat Processing and Quality. Cambridge, UK: Woodhead Publishing, pp. 211−230. Quaresma, M.A.G., Alves, S.P., Trigo-Rodrigues, I., et al., 2011. Nutritional evaluation of the lipid fraction of feral wild boar (Sus scrofa scrofa) meat. Meat Science 89 (4), 457–461. Saadoun, A., Cabrera, M.C., 2008. A review of the nutritional content and technological parameters of indigenous sources of meat in South America. Meat Science 80, 570–581. Sales, J., Kotrba, R., 2013. Meat from wild boar (Sus scrofa L.): A review. Meat Science 94, 187–201. Soon, J.M., Baines, R., 2013. Managing Food Safety Risks in the Agri-Food Industries. New York, NY: CRC Press, pp. 123−128.

Relevant Websites www.agr.gc.ca/redmeat/rpt/tbl36_eng.htm Canadian Food Inspection Agency. www.daff.gov.au Department of Agriculture, Fisheries and Forestry (DAFF), Australia. www.nda.agric.za Department of Agriculture, Forestry and Fisheries, South Africa. www.fao.org Food and Agriculture Organization of the United Nations. www.faostat.fao.org Food and Agricultural Organization Statistical Database. www.helgilibrary.com/indicators/index/game-meat-production HelgiLibrary. www.usda.gov United States Department of Agriculture.

Meat Animals, Origin and Domestication M Konarzewski, Institute of Biology, University of Białystok, Poland r 2014 Elsevier Ltd. All rights reserved.

Glossary Auroch Bos primigenius: ancestor of both Bos taurus and Bos indicus. Austronesian expansion The process of historic migration and spread of people called Austronesians from Southeast Asia (most likely Taiwan) to the Pacific region. Holocene The geological epoch which began at the end of the Pleistocene (approximately 12 000 years ago) and continues to the present. Myostatin A negative regulator of skeletal muscle growth. Neolithic A period in the development of human civilization, beginning around 10 000 BC in the Middle East.

Introduction Domestication of plants and animals was a pivotal moment in human history. It initiated the Neolithic agricultural revolution some 10 000 years ago and underpinned the spread of human civilizations. Domestication originated in only a few areas of the world and gave inhabitants of those areas enormous advantages over other people. This ultimately transformed human demography and gave rise to the modern world. Domestication of animals most likely had its roots in the ubiquitous habit of all people to capture and tame wild animals, and at first was unintentional. It probably originated as a practice of keeping and raising the young animals captured and spared in hunting. Domestication started at the end of Pleistocene, at the time of increasing unpredictability of climate and rapid reduction of numbers of game animals forced people to seek alternative and reliable food supplies.

The Nature of Domestication Domesticated animals are those that were ultimately genetically modified from their wild ancestors by artificial selection for use by humans, whose breeding and maintenance is controlled and whose food is provided for the benefit of a community or society. Domestication is thus a different process from mere taming of genetically unmodified representatives of wild species and maintaining them in captivity. The degree of suitability of wild animals for domestication depends largely on the degree of their genetic variability and the match between husbandry conditions and species-specific behavioral patterns expressed in the wild. Domestication has been restricted to surprisingly few species of mammals and birds. Particularly astonishing is the almost complete lack of domesticated mammals indigenous to subSaharan Africa, which is a homeland of the largest world populations of wild ungulates. Even African cattle probably did not evolve there

Encyclopedia of Meat Sciences, Volume 3

Order Artiodactyla Two toed mammals, e.g., sheep pigs, and cattle. Pleistocene The geological epoch which lasted from approximately 2.6 million to 12 000 years ago, spanning the period of repeated glaciations. Precocial The species in which the young are mobile and feed themselves soon after birth. Selective sweep The reduction of a local variation of the sequences of nucleotides as a result of positive natural or artificial selection.

but were possibly introduced from Southeast Asia. This suggests that there is a very unique suite of physiological and behavioral characteristics defining suitability of a particular species for domestication. All domesticated mammalian species important for meat production thrive on readily available and renewable plant food that can be harvested and stored as supplies by humans, for later use beyond the main growing period. The ability to digest poor-quality plant food limited the scope of mammalian species available for domestication to large and mediumsized animals weighing 45 kg or more and belonging to the Order Artiodactyla. Most of them (including cattle, sheep, and goats) are capable of fermenting plant material in the voluminous and highly compartmentalized stomach. The domestic pig has a simple stomach and relies on fermentation in the extended morphological structures of the hindgut. The less efficient digestion of fiber-rich plant food is, however, offset by its extremely opportunistic food habits. All ancestors of major domesticated species were precocial, that is, their offspring became mobile and able to feed themselves soon after birth, which was a prerequisite for pastoralism. Their high growth rates made them easily renewable human food resources and speeded up the process of artificial selection by promoting early sexual maturation and shortening generation time. Equally important for successful domestication are behavioral traits. All domesticated meat animals live in herds with a well-developed dominance hierarchy. In the process of domestication, humans have essentially taken over the dominant position, which enables them to manage the herds. Many species otherwise suitable for domestication are notoriously aggressive (e.g., African buffalo), have tendency to panic in enclosure (antelopes and gazelles), or are reluctant to breed in captivity (e.g., Andean vicuña). Failure to overcome problems with any of these characteristics is the most plausible reason why only 14 out of 148 mammalian species more than 45 kg body mass, potentially suitable for domestication,

doi:10.1016/B978-0-12-384731-7.00184-7

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became important as locally or globally distributed domesticated animals. However, only four of them (sheep, goat, pig, and cattle) provide the bulk of world meat production.

Origins of Domesticated Meat Animals Until recently, documentation of events of domestication in the archeological records has proved to be difficult because of equivocal discrimination of remains of domesticated animals from their wild ancestors. These difficulties have been largely overcome with the advent of analysis of the mitochondrial genome transmitted from generation to generation in maternal lineages and harbored in the egg cells. Sequences of mitochondrial DNA (mtDNA) characteristic of distinct wild populations subject to domestication events have been transmitted throughout millennia, which allow discrimination between single and multiple origins of domesticated breeds. It may also be noted that, across different species, the mutation rate of the most variable regions of mtDNA is constant and high, relative to generation time. This rate of variation constitutes the pacemaker of the so-called molecular clock and has proved to be a useful tool in reconstructing the time depth of domestication. These molecular techniques, along with other archeological evidence, have recently enabled the researchers to reconstruct fascinating histories of domestication and phylogenetic relations of major meat animals. The origins of domestic cattle, sheep, goats, pigs, and fowl, as summarized in Table 1, are briefly reviewed below.

Domestication of Cattle Among all meat-producing domesticated animals, cattle have had the most economically important role in the evolution of human cultures. There are two major types of cattle: Western cattle (Bos taurus) lacking the shoulder hump and the humped Indian zebu cattle (Bos indicus). Both types interbreed fully and therefore their status as separate species is questionable. The continued existence of many of the 800 extant cattle breeds Table 1

Wild ancestors of major meat animals and poultry and approximate dates and places of their domestication

Species Domestic cattle (Bos taurus) (Bos indicus) Sheepb (Ovis aries)

a

Wild ancestor

Date (years ago)

Place

Auroch (Bos primigenius nomadicus)

8 000–10 000

Middle East, India/Pakistan, and North Africa

8 000

Southwest Asia (Turkey and western Iran)

9 000–11 000

Euphrates Valley, Zagros Mountains, and Eastern Anatolia Near East, China, India, and Southeast Asia Southeast Asia

Goatc (Capra hircus)

Eastern Mouflon (O. orientalis) Argali (O. ammon)? Urial (Ovis vignei)? Bezoar (Capra aegagrus)

Pig (Sus scrofa)d Domestic chickene (Gallus domesticus)

Eurasian wild boar (Sus scrofa) Jungle fowl (Gallus, gallus, G. sonneratii)

a

Beja-Pereira et al. (2006); Ajmone-Marsan et al. (2010). Tapio et al. (2006); Meadows et al. (2007). c Naderi et al. (2008). d Giuffra et al. (2000). e Tixier-Boichard et al. (2011). Source: Data compiled from various sources listed in Further Reading. b

(of which, approximately 480 are recognized in Europe) is severely threatened by modern agricultural practices. According to a recent FAO report, 209 cattle breeds have become extinct (141 were of European origin) and more than 200 will be facing extinction in the near future. There is little doubt that all modern cattle breeds (with the exception of mithan and Bali cattle) were derived from the auroch or wild ox (Bos primigenius). Three subspecies of the auroch formerly roamed over vast areas of North Africa (Bos primigenius opisthonomus), Asia (B. primigenius nomadicus), and Europe (B. primigenius primigenius). The auroch became extinct approximately 2000 years ago within most of its geographical range. Small populations survived in the forested parts of Central Europe, but, despite active protection, the last individual succumbed in 1627 in Jaktorowska Forest, near Warsaw, Poland. A survey of mtDNA variation revealed that the most recent common ancestor of Western and Indian breeds of cattle lived between 330 000 and 1.7–2 million years ago – much earlier than the appearance of modern humans. Separation of African and European cattle ancestors occurred 22 000–26 000 years ago and therefore predates domestication of cattle. This suggests that each continental set of extant breeds originated as a result of separate domestication events in North Africa, the Middle East, and Southwest Asia. However, cattle domestication in Africa remains controversial, as the African mtDNA sequences differ by only few mutations from the taurine founding lineages of Southwest Asia. The genetic affinity of European cattle breeds is much closer to the breeds from Anatolia and the Middle East (i.e., B. primigenius nomadicus) than to now-extinct European populations of the auroch B. primigenius primigenius. However, mtDNA sequencing points to the possibility of several, local introgressions from wild aurochs. In any case, the extant European breeds can be mostly considered as derivatives of cattle expanding some 5000 years ago from a center of domestication located in the region of the Fertile Crescent (the area encompassing southern Turkey, northern parts of Jordan, Syria, and Iraq). It is, therefore, unlikely that initial local

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Species of Meat Animals | Meat Animals, Origin and Domestication domestication contributed significantly to the establishment of European agriculture, even though separated events might have taken place in Southern Europe (Italy). A genome-wide single nucleotide polymorphism (SNP) analysis suggests that cattle were introduced into Europe sequentially, through Turkey and the Balkans. It then radiated via Central Europe and France, reaching the British Isles. Modern south European cattle breeds also carry genetic signatures of North African origin, most likely imported through the Iberian Peninsula. Taurine cattle (B. taurus) were domesticated from the B. primigenius nomadicus 8000–10 000 years ago. The earliest, 7800-year-old, archeological evidence of B. taurus has been found in Anatolia (Turkey). Remains of B. indicus dated to be at least 4500 years old have been unearthed in Iran, Mesopotamia, and the Indus valley. The analyses of mtDNA suggest that zebu cattle must have been domesticated much earlier, some 8000–10 000 years ago. Archeological evidence of cattle herding from 7000 years ago points to Pakistan as a potential domestication center of zebu cattle. The oldest (9000 years ago) African Bos remains that can be putatively associated with domestication were found in eastern Sahara, although its domestication remains controversial. In contrast to the extant humped African cattle, the earliest cattle were humpless. Although humped African cattle have the distinct morphological characteristics also present in Indian breeds, their mtDNA sequence is much closer to that of B. taurus. In contrast, the nuclear DNA of African breeds bears the signature of Indian zebu cattle. The apparent lack of mtDNA of zebu cattle in African breeds along with the presence of zebu cattle sequences in nuclear DNA of African breeds strongly suggests a deliberate breeding of African zebu-type females, bearing B. taurus mtDNA sequences, with zebu males of Asian origin. These males were most likely imported into Africa during the Arab invasions of the AD eighth century. Interestingly, as a secondary consequence of the slave trade, North African mtDNA sequences have been found in cattle from southern Portugal. New World cattle breeds are descendants of cattle brought by Europeans as early as 1493, and bear genetic signatures of the taurine and indicine lineages, including African admixture. The latter may account for the elevated disease resistance of such breeds as Texas Longhorn.

Domestication of Sheep Recent molecular phylogenies of the wild sheep, based on sequences of cytochrome b and Y chromosome (MSY), suggest that Ovis species consist of four phylogenetic groups, three of which (Moufloniform, Argaliform I, and Argaliform II) are native to Eurasia. Domestic sheep belongs to the Moufloniforms, along with three wild species: urial (O. vignei), eastern mouflon O. orientalis, and European mouflon (O. musimon). All of them produce fertile and viable offspring when bred in captivity. European mouflon is the only species to share a haplotype with domestic sheep, which agrees with its feral domesticated status, that has undergone male-mediated introgression with domestic breeds. Eurasian wild sheep – eastern mouflon, urial, and argali (O. ammon) – have been suggested as potential progenitors of

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domestic sheep. Earlier studies indicated that one of the oldest domesticated forms of sheep probably originated some 8000 years ago from urial in the region of the Caspian Sea and was subsequently adopted by the people of the Middle East and later also by early European herders. However, recent mtDNA analysis separated the phylogenetic tree of domestic sheep into five distinct mitochondrial maternal lineages (hyplotype groups A–E), which suggest multiple, independent domestication events. Highly diverged lineages A–D are mainly found in the Caucasus, lineages A–C in Central Asia, whereas A and B in the eastern edge of Europe. Lineage C sequences have also been found in sheep from Portugal, most likely indicating gene flow from the Fertile Crescent to the Iberian Peninsula. The European mouflon is aligned to lineage B. Lineage D has been identified in a single animal sampled from the north Caucasus and therefore awaits further confirmation. Southern European sheep breeds have higher genetic diversity and are less genetically differentiated compared with breeds from northern Europe. This most likely reflects geographic gradient with highest genetic diversity close to the center of domestication, in the Near East, which still remains a sheep genetic diversity hotspot. According to FAO estimates, 36% of the extant sheep breeds are either extinct or endangered.

Domestication of Goats Domestication of goats (Capra hircus) may have played a key role in the Neolithic agricultural revolution and the spread of agriculture from its earliest homelands. The extreme ability of goats to thrive on poor-quality fodder and to cope with harsh environmental conditions makes them the most geographically widespread, domesticated herbivorous species, ranging from cold Siberian mountains to the driest parts of North Africa. Archeological evidence suggests that the bezoar (Capra aegagrus), the wild progenitor of the domestic goat, was the first wild ungulate to be domesticated. Domestication most likely took place in the region of the Fertile Crescent. Recent analyses of genetic diversity of the domestic goat have revealed six distinct mtDNA lineages, with more than 90% of analyzed individuals belonging to lineage A. This lineage, as well as lineage C, most likely originated in Eastern Anatolia, where they are common in wild populations. This points to Eastern Anatolia as the major center of goat domestication. Lineages B, D, F, and G are found in less than 8% of domestic goats and were most likely integrated to the gene pool following independent, small-scale domestications events in Northern and Central Zagros Mountains. However, recent analyses do not confirm an independent domestication in the Indus Valley. Goats must often have been human companions, both in commercial trade as well as during migrations and explorations. The geographic distribution of genetic variation of the extant lineages of goats is much less diversified than that in cattle. Intercontinental differences between goat populations account for only 10% of the total mtDNA variation, whereas genetic differences between cattle breeds on different continents explain more than 80% of the variation. This attests to an intensive intercontinental gene flow between goat populations, which resulted from long-distance transportation of goats along ancient trading routes.

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Domestication of Pigs There are two major forms of domestic pigs, European and Asian, whose distinctiveness was recognized by earlier authors including Charles Darwin. Because of marked, morphological differences, both forms were assumed to originate from different species of wild boar. However, recent mtDNA analysis revealed that wild boar originated in western islands of Southeast Asia, and then dispersed to Indian subcontinent. Subsequent radiation of Sus scrofa into East Asia was followed by a progressive spread across Eurasia and into Western Europe. The time since divergence from the common ancestor of European and Asian forms of pig falls well outside the known history of animal domestication and has been estimated at 500 000 years ago. This provides strong evidence for independent domestication of pigs in Europe and Asia, approximately 9000 years ago. However, domestication was predated by a long period of wild boar management that started about the time of the Pleistocene/Holocene transition, as exemplified by the man-made introduction of this species to Cyprus 12 000 years ago. Likewise, phylogeographic structure of pig mitochondrial sequences attests to a significant human contribution to dispersal of this species across Europe (particularly the Mediterranean islands) and the Middle East. Initially, domestic pigs managed in Europe during the Neolithic Era were of Near Eastern ancestry. By the early fourth millennium BC, local European wild boars were also domesticated. This domestication cannot be, therefore, regarded as truly independent, but rather as a consequence of the introduction of Near Eastern domestic pigs. Once domesticated, European pigs rapidly replaced the introduced Near Eastern pig lineages throughout Europe in a relatively short period of approximately 500 years and later began replacing indigenous Near Eastern pigs. In Asia, pigs were independently domesticated in at least six locations: China, India, peninsular Southeast Asia (three locations), and off the coast of Taiwan. Some extant European pig breeds (e.g., European Large White) are characterized by high frequency of mtDNA haplotypes of Asian origin. This is most likely a legacy of well-documented European breeding practices of the eighteenth and nineteenth centuries, when Asian sows were used to improve the contemporary breeds.

Domestication of Poultry Although the meat yield of wild birds was far lower than that of much bigger mammals, attempts to domesticate fowl have a long history and have been independently undertaken on all continents inhabited by humans. Various breeds of duck and geese species were successfully domesticated in Eurasia, turkeys in Mesoamerica, and guinea fowl in Africa, whereas the extant breeds of Muscovy duck originated in South America. The earliest remains of domestic chickens were excavated in numerous archeological sites along the Yellow River in China and dated to be at least 7500 years old. They were also found in the Indus Valley in Pakistan. The 4000-year-old remains unearthed in Spain and Ukraine attest an incredibly rapid spread of the domestic chicken. Approximately 3600 years ago, chickens were introduced to New Guinea and quickly reached Pacific islands during Austronesian expansion. This fast initial

dispersion can be attributed primarily to the ease of transportation of the fowl. Another important factor could have been a religious significance attached to the chicken as a divine offering, widespread in different parts of the world. Earlier analyses of mtDNA sequences pointed to the area of Thailand as a single location of the domestication of chickens. Recent extensive survey of mtDNA sequences from domestic chickens and four red jungle fowl subspecies (G. g. gallus, G. g. bankiva, G. g. spadiceus, and G. g. jabouillei) identified nine highly divergent lineages A–I. Seven of them consists of both wild and domestic individuals and are confined to Asia, which strongly suggests that chicken domestication took place independently in different regions of India and China. However, the ubiquitous presence of the E lineage, native to India, suggests that worldwide expansion of domestic chickens took place from there.

Changes in Species under Domestication Behavioral Changes of Animals under Domestication Domestic breeds diverged from their wild ancestors in many ways. Because heritabilities of behavioral traits are usually higher than heritabilities of anatomical and physiological traits, one can speculate that the development of domestic phenotypes started with changes of the behavior of animals undergoing domestication. The most obvious change was the loss of fear of humans. Equally important behavioral changes involved increasing of the threshold of within-species and between-species aggression. This has become essential for the successful maintenance of stocks of domesticated animals living under population densities far exceeding maximum densities tolerated under natural conditions, often next to large stocks of unrelated species. Perhaps the most important effect of domestication on behavior was a reduction of the sensitivity to changes in the unfamiliar environment. This stemmed from reduced emotional reactivity to handling by humans and ease of adaptation to novel conditions, which greatly contributed to the high reproductive rates essential for the success of artificial selection. It is important to note that a successful domestication required the fulfillment of all conditions mentioned above and therefore could have been achieved only with particularly prone individual animals. For example, recent computer simulations revealed that cattle domesticated in the area of modern Iran originated from just 80 female aurochs, which attest to the difficulties of the early stages of cattle herding and breeding.

Morphological and Anatomical Changes of Animals under Domestication Domestication has also resulted in profound changes in the morphology and anatomy of animals. Primitive breeds of domestic pigs, sheep, goats, and cattle were generally smaller than their wild ancestors, which most likely make them more manageable, as pointed out by Francis Galton in 1865. Chickens, in turn, were selected to be larger. The whole brain volume of domesticated animals is 10% less than in their wild relatives. The decrease of brain sensory centers is particularly

Species of Meat Animals | Meat Animals, Origin and Domestication clear cut and corresponds well with the observed behavioral differences between domestic animals and their wild relatives. An incredible increase of growth rate of modern meat-type strains of domestic fowl is one of the best examples of both the power of intense, directional selection and its negative side effects. During the late 1940s, broilers took approximately 90 days to grow to slaughter body mass of 1800 g. Now it takes less than half of this time to reach the slaughter mass of 2500 g. Surprisingly, most of this progress has arisen through an increase of growth rates during the first two weeks of postembryonic development. However, this impressive selection progress also incurred unavoidable costs associated with increasing incidence of metabolic diseases such as ‘heart failure syndrome,’ sometimes killing 10% of a broiler flock. In addition, changes in body proportions, such as that resulting from selection for large breast size in domestic turkeys, have severely impaired their mating behavior, and selection for intense egg production resulted in total loss of incubation and brooding behavior in laying hens.

Genetic Footprints of Domestication Studies on genetics of domestication have been greatly advanced, thanks to the development of the quantitative genetics theory and molecular genetics techniques. Although still in its early stages, identification of quantitative trait loci (QTL) and whole genome sequencing have become powerful approaches that have been recently applied to detect genetic footprints of domestication. For example, one of the most important selective sweeps already identified in poultry occurred at the locus for thyroid-stimulating hormone receptor (TSHR), which underlies hormonal regulation of reproduction, photoperiod, and metabolic rates. Research on the differences in expression of polygenic traits in pigs and wild boars has resulted in the identification of loci, such as insulin-like growth factor 2 (IGF2) associated with muscularity, fat accumulation, and heart size. Domestication has also almost certainly led to near fixation of naturally occurring mutations of gene coding for GDF-8 (myostatin, a negative regulator of skeletal muscle growth) in several cattle breeds such as Belgian Blue. However, high density single nuclear polymorphism (SNP) genotyping has indicated that 50% of ancestral genetic diversity has been already lost in the extant cattle breeds.

Consequences of Domestication for Meat Composition Ample anthropological and ethnographic evidences indicate that humans are evolutionarily preadapted to a diet that includes meat. There is also little doubt that scavenged or hunted ruminants were the main source of meat throughout early human history. Human dietary lipid requirements are, therefore, more likely to match the lipid composition of wild ruminant tissues. This composition is qualitatively and quantitatively different from the lipid profiles of meat of domesticated cattle, which may have important consequences for the health of modern consumers. The most significant difference between meat composition of wild and domesticated ruminants is the relative amount of fat per unit mass of muscle tissue. Meat of grain-fed beef

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(trimmed of all adherent fat) contains 2–3 times more fat (mean 5.6 g per 100 g tissue) than the muscle of wild ungulates such as antelope, deer, or buffalo (mean 2.2 g per 100 g tissue). The high fat content of beef muscle tissues is mainly associated with the formation of intramuscular fat deposits – a phenomenon known as marbling of meat – which is largely absent in wild ruminants. This intramuscular fat is rich in triacylglycerols and resembles subcutaneous fat with respect to the profile of fatty acids. Another important difference is that muscle tissue of wild ruminants contains a higher proportion of polyunsaturated fatty acids (PUFAs) than muscles of domestic cattle. Up to 30% of all fatty acids contained in game meat are polyunsaturated, whereas PUFAs account for only 10% of FAs in beef. Increased levels of saturated fat in beef (particularly 12:0, 14:0, and 16:0 fatty acids) have substantially contributed to increased dietary fatty acid levels in the modern westernized diet. This, in turn, may be associated with an increased risk of cardiovascular disease if not taken into account in a diet. Moreover, muscles of domesticated cattle are much poorer in long-chain PUFAs (particularly n-3 long-chain PUFAs), as compared with muscles of wild ruminants. It is important to note, however, that there are also significant differences in the muscle fat content and composition between pasture-fed and grain-fed cattle. Muscles of grain-fed cattle are particularly rich in saturated and monounsaturated fats, whereas the lipid profiles of pasture-fed cattle resemble those of game meat. Thus, the differences in meat composition between wild and domesticated ungulates can be largely attributed to the practice of feeding cattle grain, rather than to physiological changes incurred by the process of domestication.

The Future of Domestication of Meat Animals The incredible progress of modern biology has made it possible not only to maintain but also to breed in captivity almost all terrestrial mammals. Some of them such as moose (Alces alces), red deer (Cervus elaphus), or American bison (Bison bison) have been domesticated to some extent in the past century. They are, however, generally still unsuitable for intense meat-producing farming, they cannot be herded for a long time, and it is unlikely that they will soon join a very short list of major meat-producing species. However, together with primitive breeds of already domesticated animals, they can serve as a source of meat of very desirable protein and fat profiles. Growing health concerns of consumers may paradoxically give rise to selection of meat animals: toward emulation of the meat composition of their wild ancestors.

See also: Animal Breeding and Genetics: DNA Markers and Marker-Assisted Selection in the Genomic Era; Traditional Animal Breeding. Chemical Analysis for Specific Components: Major Meat Components. Human Nutrition: Cancer Health Concerns; Cardiovascular and Obesity Health Concerns. Slaughter-Line Operation: Poultry. Species of Meat Animals: Cattle; Game and Exotic Animals; Pigs

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Further Reading Ajmone-Marsan, P., Garcia, J.F., Lenstra, J.A., et al., 2010. On the origin of cattle: How Aurochs became cattle and colonized the world. Evolutionary Anthropology 19, 148–157. Beja-Pereira, A., Caramelli, D., Lalueza-Foxe, C., et al., 2006. The origin of European cattle: Evidence from modern and ancient DNA. Proceedings of the National Academy of Sciences of the USA 103, 8113–8118. Cordain, L., Watkins, B.A., Florant, G.L., et al., 2002. Fatty acid analysis of wild ruminant tissues: Evolutionary implications for reducing diet-related chronic disease. European Journal of Clinical Nutrition 56, 181–191. Diamond, J., 1997. Guns, Germs, and Steel: The Fates of Human Societies. New York: Norton. Diamond, J., 2002. Evolution, consequences and future of plant and animal domestication. Nature 418, 700–707. Giuffra, E., Kijas, J.M.H., Amarger, V., et al., 2000. The origin of the domestic pig: Independent domestication and subsequent introgression. Genetics 154, 1785–1791. Larson, G., Liu, K.R., Zhao, X., et al., 2010. Patterns of East Asian pig domestication, migration, and turnover revealed by modern and ancient DNA. Proceedings of the National Academy of Sciences of the USA 107, 7686–7691. Luikart, G., Gielly, L., Excoffier, L., et al., 2001. Multiple maternal origins and weak paleographic structure in domestic goats. Proceedings of the National Academy of Sciences of the USA 98, 5927–5932. McTavish, E.J., Decker, J.E., Schnabel, R.D., 2013. New World cattle show ancestry from multiple independent domestication events. Proceedings of the National Academy of Sciences of the USA. doi:10.1073/pnas.1303367110. Meadows, J.R.S., Cemal, I., Karaca, O., et al., 2007. Five Ovine mitochondrial lineages identified from sheep breeds of the Near East. Genetics 175, 1371–1379.

Naderi, S., Razaei, H.-S., Pompanon, F., et al., 2008. The goat domestication process inferred from large-scale mitochondrial DNA analysis of wild and domestic individuals. Proceedings of the National Academy of Sciences of the USA 105, 17659–17664. Price, E.O., 1999. Behavioral development in animals undergoing domestication. Applied Animal Behaviour Science 65, 245–271. Tapio, M., Marzanov, N., Ozerov, M., et al., 2006. Sheep mitochondrial DNA variation in European, Caucasian and Central Asian areas. Molecular Biology and Evolution 23, 1776–1783. Tixier-Boichard, M., Bed′hom, B., Rognon, X., 2011. Chicken domestication: From archeology to genomics. Comptes Rendus Biologie 334, 197–204. Rubin, C.-J., Zody, M.C., Eriksson, J., et al., 2010. Whole-genome resequencing reveals loci under selection during chicken domestication. Nature 464, 587–593. Zeder, M.A., Emshwiller, E., Smith, B.D., et al., 2006. Documenting domestication: the intersection of genetics and archaeology. Trends in Genetics 22, 139–155.

Relevant Websites http://www.ansi.okstate.edu/breeds/cattle/ Breeds of Livestock. http://www.fao.org/dad-is/ Domestic Animal Diversity Information System (DAD-IS). http://en.wikipedia.org/wiki/Cattle General Information on Cattle. http://en.wikipedia.org/wiki/Jungle_fowl General Information on Jungle Fowl. http://www.fao.org/docrep/w7540e/w7540e0h.htm Wildlife Farming and Domestication.

Pigs DD Boler, University of Illinois, Urbana, IL, USA r 2014 Elsevier Ltd. All rights reserved. This article is a revision of the previous edition article by G Eikelenboom, P Walstra, JH Huiskes, RE Klont, volume 3, pp 1284–1291, © 2004 Elsevier Ltd.

Glossary Allometric growth The increase in size of different organs or parts of the same animal at differing rates. Cutability An estimation of boneless closely trimmed retail cuts derived from a carcass. Iodine value An indication of unsaturation levels in a fat sample. It used to be reported in units of grams of I per

Introduction The global pork industry produces more than 100 million tons of pork annually and is the most consumed meat animal protein in the world. China is the world’s leader in pork production and provides approximately 50% of the global supply. The European Union is estimated to be second at more than 20% and the US is third at a little more than 10% of the worlds pork supply. Together Brazil and Russia account for a little more than 5% of the world's pork production. Recent improvements in the efficiency and volume of pork production are largely related to increases in sow productivity and marketing of pigs at heavier slaughter weights than have been historically reported. Pig production varies greatly around the world. Some production systems, such as Australia and the UK, raise and market entire males, but slaughter them at younger ages before reaching puberty to avoid undesirable boar odor compounds. Other markets, such as the US and Brazil, generally castrate male pigs at a very young age to prevent the development of boar odors. Some parts of the world have very sophisticated vertical integration marketing systems, whereas others still rely on an open market system to buy and sell pigs for food production. Just as there are differences in how pigs are raised and sold around the world, there are differences in how the value of pig carcasses is determined. The objective of this article is to discuss growth rates and composition of pork carcasses, metabolism of early postmortem carcasses and how it influences meat quality, differences in dressing percentage, fabrication techniques, and fat quality.

Growth and Carcass Composition Body composition changes dramatically as animals grow. Pigs have the greatest proportion of muscle at birth but it slowly declines as they grow and accumulate fat. As a rule, soft tissue comprises more than 50% water and can be as high as 90%. Protein is usually second in terms of weight, except in the cases of very fat animals. Therefore, fat is the most variable tissue in

Encyclopedia of Meat Sciences, Volume 3

100 g of tissue. In chemistry, it is the mass of iodine in grams that is consumed by 100 g of tissue. Lairage A period of rest between the time the animal is delivered to the slaughter facility until the animal is actually slaughtered. Metabolic modifier Compounds that are fed, injected, or implanted in animal to improve production efficiency.

the body and can be second or third in terms of live body weight. After all, fat serves the body as an energy reserve in times of need. Additionally, fat provides insulation, protection of vital organs, and generation of heat. From a chemical element standpoint, greater than 50% of body mass is oxygen, approximately 20% carbon, 10% hydrogen, and approximately 3% nitrogen. These are the elements that make up water, protein, carbohydrate, and fat. As a rule, animals partition nutrients for tissue development in order of skeleton, muscle, and then fat. They tend to deposit fat in the mesenteric regions first followed by perirenal (mesenteric and perirenal depots are sometimes jointly called visceral fat), then subcutaneous (backfat), intermuscular (seam), and finally intramuscular (marbling) fat deposition. Even so, it is important to remember that fat accretion is not a linear process. Pigs simultaneously deposit fat in different anatomical regions of the body throughout development. Subcutaneous fat makes up the largest portion of total fat in pork carcasses and is being deposited at a faster rate than intermuscular fat toward the end of pigs' growth. Intramuscular fat is generally considered the last fat depot to develop and thus makes up the least proportion of total fat. As mentioned, after animals are born, the proportion of muscle in the body begins to decrease and the proportion of fat increases. The rate and magnitude at which fat accumulates and muscle decreases can be breed and sex dependent. Heritage pig breeds, such as Berkshire, tend to grow at a slower rate and finish with a greater proportion of fat than most high-lean, terminal crossbred pigs. Heritage breeds are often referred to as earlier-maturing breeds because of the increased proportion of fat, slower growth rate, and smaller mature body frame size relative to more commercially raised composite breeds. Differences in body composition are more pronounced when pigs of different mature frame sizes are compared at the same weight, rather than at the same age. At equal body weights, barrows will be fatter than gilts and gilts will be fatter than entire males when assessed at the area of the tenth rib. Conversely, entire males will have a greater percentage of fat-free lean than gilts and gilts will have a greater proportion of fat-free lean than barrows. During the growth period, young entire males will have a greater percentage of

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lean than fat. Barrows will eventually reach a point that deposition of fat will exceed deposition of muscle. During the last few weeks of the finishing phase, barrows tend to consume more feed than entire males and gilts. Gilts tend to gain less weight per day than barrows and usually require more days on feed to reach a desired body weight than barrows. Pigs fed a diet that is greater in protein concentration than considered necessary for growth will have a greater lean meat percentage. Additionally, seasonality can play a role in carcass composition. In warm weather, pigs tend to eat less and gain less weight per day than during colder seasons. In production systems where the flow of pigs through the system is tightly managed and feed costs are expensive, it might not be possible to allow pigs to stay on feed to achieve the desired ending live weight. Pigs raised during the hot months of the year tend to be lighter, have less backfat, and greater estimated lean percentages than pigs raised during the cold months. Metabolic modifiers are compounds that are injected, fed, or implanted to improve growth rate, carcass cutability, or other production enhancing characteristics. There are currently two metabolic modifiers used in pork production in various parts of the world to influence carcass composition. The first is ractopamine hydrochloride (trade name PayleanTM) and is commonly used in the US and Brazil pork production operations. Ractopamine is a β-adrenergic agonist that increases growth rate, feed efficiency, and carcass leanness of finishing pigs fed a diet with at least 16% crude protein for the last 20– 41 kg before harvest. Feeding ractopamine will slightly reduce tenth rib fat thickness and increase loin muscle area or depth. This translates into a modification of allometric growth rates of various primal pieces and an increase in carcass cutability. The second metabolic modifier is the use of immunological castration as an alternative to physical castration. Immunological castration has been adopted in some parts of the world. It is achieved through a series of two injections that act as an immunological metabolic modifier by changing the natural hormone profile after the second injection. Immunological castration occurs later in life than physical castration and is used to suppress testicular function to reduce boar taint in intact male pigs intended for harvest. The technology was developed in Australia and is now approved for use in more than 60 countries worldwide. Immunologically castrated male pigs also have improved growth rate, feed efficiency, and carcass cutability when compared with physically castrated male pigs.

allotted space per pig in a pen, decreases competition for feeder access, and allows slower growing pigs more time to reach a desired compositional end point. This marketing approach allows producers to be rewarded for marketing pigs that have a desired carcass weight (not too heavy or too light) with minimal carcass weight variation and a desired percentage of lean meat. In many pork slaughter facilities, estimation of carcass leanness is carried out at the very end of the harvest process. Carcass leanness estimations can be accomplished using a variety of technologies. The use and application of these technologies vary greatly around the world. Some examples include: the Fat-o-Meater, Hennessy probe, animal ultrasound system, or a simple ruler to measure fat thickness. Some of these technologies are more invasive than others. So, the method used to determine carcass composition will vary among packers and regions of the world. Other technologies, such as dual energy X-ray absorptiometry, are available to determine carcass leanness, but might be prohibitive in a largescale fast moving production facility. As fat thickness or fat content is the most variable tissue in carcasses, it plays a very influential role in estimating carcasses lean percentage. Therefore, fat thickness is included in nearly every regression equation, regardless of technology used, to estimate carcass lean percentage. Even though the value of carcasses to the live pig producer is determined by carcass weight and estimation of carcass leanness, the value of carcasses to packers is determined by the cutability of carcasses or the amount of meat products derived from those carcasses. In the US, pork carcasses are fabricated into five primal pieces (Figure 1). Those pieces are the ham (22–25% of the chilled half carcass), loin (20–22% of the chilled half carcass), picnic shoulder (ventral region of the shoulder, which accounts for approximately 9–11% of the chilled half carcass), belly (12–15% of the chilled half carcass), and Boston butt shoulder (dorsal region of the shoulder, which accounts for approximately 8–10% of the chilled half carcass). The Boston butt, picnic, loin, and ham are often referred to as the four lean cuts or lean carcass cutability. When the belly is included, the calculation is referred to as carcass cutability. Lean carcasses generally have a greater cutability than fatter carcasses because there is less fat (also less valuable) to trim away, thereby a greater percentage of carcasses can be sold as lean meat. In Europe, carcasses are classified based on lean meat percentage using the EUROP classification system that is based on

Carcass Classification (b)

In various parts of the world, a pig's value is determined by carcass weight and an estimation of carcass leanness. In the US, pigs generally are marketed from a single barn over potentially several weeks. The majority of pigs are sold on a matrix type basis that offer premiums for carcasses meeting certain specifications and charges discounts to carcasses that do not comply with the desired carcass weight and lean meat percentage specifications. By doing this, producers are able to better manage carcass weight as well as carcass composition. This can be accomplished by marketing the heaviest pigs within a pen first, and then lighter pigs in subsequent weeks. This increases

(c)

(a) (d)

(e)

Figure 1 A pork carcass fabricated into the five US primal pieces: (a) ham (22–25% of chilled half carcass), (b) loin (20–22% of chilled half carcass), (c) Boston butt (8–10% of chilled half shoulder), (d) belly (12–15% of chilled half carcass), and (e) picnic shoulder (9–11% of chilled half carcass).

Species of Meat Animals | Pigs muscle and fat thickness. In that system, E has the greatest lean meat percentage (455%), U ¼ 50–55% lean meat, R¼ 45– 50% lean meat, O ¼ 40–45% lean meat, and P is the least lean meat percentage (o40%). Similar to the US, European packers also estimate lean meat percentage with objective tools such as a caliper to determine midline fat thickness, Fat-o-Meater and Hennessy optical probes, and various ultrasonic scanners.

Dressing Percentage Dressing percentage, or carcass yield as it is sometimes referred to, is the proportion of ending live weight yielded after animals have been stunned (desensitized), exsanguinated, skinned or scalded, and eviscerated. The average dressing percentage of pigs in the US is approximately 74%. Average dressing percentages will vary in other parts of the world depending on several factors. Sex of animals is one such factor with entire males usually having a lesser dressing percentage than castrated male or female pigs. This can be partially attributed to the presence of testicles of entire male pigs, which accounts for approximately 0.5–0.7% of ending live weight. Reduced fatness of entire male pigs also decreases dressing percentage. Diet can also impact dressing percentage. Finishing diets that are high in fiber can reduce dressing percentage. It is thought that diets rich in fiber, such as those that contain distillers dried grains (ethanol coproducts), increase intestinal mass, which is approximately 3% of ending live weight, and reduce dressing percentage due to a larger portion of live weight from intestinal mass. In addition to intestinal mass, transport distance, gut fill, and time spent in lairage also will influence dressing percentage. Lairage is the time from when animals arrive at the harvest facility until animals are slaughtered. Pigs are not usually fed during transport and lairage unless they jointly exceed 24 h. Therefore, as transport and lairage time increases, gut fill generally decreases and thereby increasing the dressing percentage. Gut fill, even after a 15-h lairage period can be as much as 5% of ending live weight. Not only can things such as sex, diet, composition, and transportation/lairage loss influence dressing percentage, but the actual dressing process itself can also greatly impact dressing percentage. Some parts of the world leave the head attached to carcasses or leave the front feet intact. The head can account for 5–7% of ending live weight and the front feet, depending on the anatomical removal location, can account for approximately 1% of ending live weight. Skin can account for approximately 4–6% of ending live weight when carcasses are skinned rather than scalded and can be much greater depending on the skill level of persons skinning the carcasses. Other visceral organs that can influence dressing percentage are the heart (∼0.4%), liver (∼1.7%), and the kidneys (∼0.5%) and can be influenced by a variety of management practices. Time of harvest in relation to the biological growth curve will also influence dressing percentage. Live animals that are destined for harvest can be divided into a carcass component and a noncarcass component. Early in life, noncarcass components, such as blood, viscera, and skin in some cases will make up a greater proportion of live weight than later in life. As animals reach maturity, visceral growth is completed and animals begin to accumulate fat at a more rapid rate. Carcass

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components begin to increase in proportion to live weight relative to noncarcass components, thereby increasing the dressing percentage. Therefore, larger, heavier, and older animals usually have a greater dressing percentage than young, growing animals. Even though noncarcass components are considered byproducts, they represent a great deal of value to the pork industry in the US and other countries. Drop value, or the value of ears, hearts, livers, tongues, snouts, salivary glands, and other noncarcass component byproducts can be worth approximately US$5 per cwt per pig or in some cases even more.

Meat Quality Shortly after animals are stunned, they are exsanguinated. When animals are exsanguinated, the circulatory system is disrupted and homeostasis is lost. A series of metabolic and biochemical reactions take place in an attempt to regain homeostasis. Thus, exsanguination begins the conversion of muscle to meat. During the conversion of muscle to meat, tissue pH declines from approximately 7.2 in living muscle to an ultimate pH of approximately 5.7 but can range from 5.2 to 6.5 in very extreme cases. In rare cases, the magnitude may be even greater. Ultimate pH, or the pH after postmortem metabolism has concluded, usually between 12 and 24 postmortem, is often the first topic of discussion when evaluating meat quality because it shares the greatest relationship with other meat quality parameters such as color, water-holding capacity, and texture or firmness. Ultimate pH is measured as the inverse log of the [H+] ion concentration. In living animals, the circulatory system transports oxygen, dissipates heat, and removes waste from various tissues. As blood is removed during the conversion of muscle to meat, carcasses undergo transition from aerobic postmortem metabolism to anaerobic postmortem metabolism. In an anaerobic environment, the carbohydrate source used to produce adenosine triphosphate is converted from pyruvate into lactic acid rather than from pyruvate to acetyl CoA as is the case in living muscle. As there is no blood available to remove lactic acid, it begins to accumulate and results in postmortem muscle pH decline. The rate and magnitude of pH decline will have noticeable effects on meat quality. When little carbohydrate is available at the time of death, usually due to chronic stress, very little pH decline occurs. This condition is referred to as dark, firm, and dry (DFD). Water-holding capacity is inversely related to ultimate pH. So, in DFD conditions, water-holding capacity is at its greatest. Water is bound tightly within the muscle cells and makes the surface of the meat appear very dry. When the surface of the meat is dry, light is absorbed into the tissue rather than reflected or scattered from the surface. This causes the surface of the meat to appear dark (similar to a color score of 6; Figure 2). A condition opposite to DFD is known as pale, soft, and exudative (PSE). This condition occurs in part due to acute stress shortly before the animals are harvested. Excessive available glycogen at the time of death can result in a rapid rate of pH decline when carcass temperatures are relatively warm. The combination of low pH and high temperatures denatures sarcoplasmic and myofibrillar proteins. When this happens, water becomes loosely associated with muscle cells

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Figure 2 Pork quality standards for color–texture–exudation of hams (top), color standards of loins (middle) and marbling (bottom). Provided courtesy of the National Pork Board and Pork Checkoff.

and tends to pool on the surface. This is what is referred to as exudative. Moisture on the cut surface of meat tends to reflect rather than absorb light making the color appear light (similar to a color score of 1; Figure 2). Proper environmental conditions and handling practices can aid in preventing PSE and DFD from occurring. Another metabolic condition is referred to as acid meat. Acid meat is a condition sometimes found in the Hampshire breed where excess glycogen is stored in the muscle and results in very low ultimate pH values when animals are harvested. This condition is different from PSE, however, in that the rate of pH decline is normal but the magnitude of pH decline is greater. Pigs that store excessive amounts of glycogen in their muscles are suspect for extended postmortem pH decline and a greater concentration of lactic acid in the postmortem tissue. These pigs are referred to as having a high glycolytic potential. This phenomenon is often referred to as the ‘Hampshire effect’ caused by the Rendement Napole gene. The dominant allele (RN-) is responsible for the increased muscle glycogen levels. The RN- mutation is a singlenucleotide polymorphism of a gene that encodes for a regulatory subunit of adenosine monophosphate-activated protein kinase. New literature available now indicates that postmortem pH decline may be more complex than originally thought.

All three of these metabolic conditions are a concern for the pork industry because they negatively influence palatability. Palatability is generally referred to as the combination of tenderness, juiciness, and flavor of cooked meat. These three things together will largely impact consumers eating experiences. However, color is often cited as the primary parameter involved in consumers intent to purchase. Myoglobin is the sarcoplasmic protein that gives meat its color. Myoglobin concentration tends to increase as animals age due to a loss of affinity to oxygen. As a rule, however, pigs have approximately 2 mg of myoglobin per gram of muscle. Entire males tend to have a slightly greater myoglobin concentration than castrates or gilts. Producers are not often directly compensated for lean muscle quality. In some cases, such as product meeting export specifications, a premium may be offered but, in general, there are no value-based premiums for meat quality parameters. This is largely because quality is subjective in nature and can be difficult to measure in real time. Tenderness is often the most influential parameter in determining the eating experiences of the consumers. A new technology is being developed to classify pork loins based on tenderness levels. Pork is generally considered tender, but the genetic selection of lean fast

Species of Meat Animals | Pigs growing pigs may negatively influence tenderness. Visible and near-infrared reflectance spectroscopy can allow packers to noninvasively predict tenderness on the fabrication line of plants. Eating meat provides several important dietary nutrients. Meat consumption directly contributes to a low glycemic index because meat is low in carbohydrates. Dietary protein from meat provides necessary amino acids needed for muscle growth and maintenance of tissue. Meat consumption is an excellent source of minerals such as iron, calcium, and zinc. Meat is also a good source of all four fat soluble vitamins (A, D, E, and K). Pork, in particular, is a good source of B vitamins. Pork consumption also provides selenium, which is a natural antioxidant via glutathione peroxidase.

Fat Quality Over the past couple of decades, pigs have become leaner. Leaner pigs tend to have greater concentration of polyunsaturated fatty acids (PUFA) than fat pigs. The type of fat (saturated or unsaturated) in various fat depots can impact consumers perceptions, shelf-life, processing capabilities, and bacon characteristics of pork products derived from those fats. Fat quality can be described using a variety of parameters, but is most commonly discussed in terms of iodine values. An iodine value is an indication of the level of unsaturation in fat samples. Iodine values are most commonly calculated using a regression equation based on fatty acid concentrations: iodine value (IV) ¼ 16:1 (0.95)+18:1 (0.86)+18:2 (1.732)+18:3 (2.616)+20:1 (0.785)+22:1 (0.723). More recently, a similar equation has been offered that includes most of the previous coefficients, but also includes some longer chained fatty acids. A newer equation for iodine value is as follows: IV¼ 16:1 (0.95)+18:1 (0.86)+18:2 (1.732)+18:3 (2.616)+20:1 (0.795) +20:2 (1.57)+20:3 (2.38)+20:4 (3.19)+20:5 (4.01)+22:4 (2.93) +22:5 (3.68)+22:6 (4.64). As IV increases, fat firmness decreases and shelf-life of products becomes shorter. Lipid oxidation is one of the primary processes involved in quality losses of pork products. The oxidative breakdown of PUFA leads to rancidity and development of undesirable odors and flavors. Fat quality can also be assessed by measuring the thickness of the belly. Generally speaking, fatter pigs have thicker bellies and a greater proportion of saturated fatty acids than lean pigs. This means the bellies are firmer and easier to slice into bacon. Pork fat can range from less than 25% PUFA to greater than 35% PUFA and is dependent on things such as diet, sex, season, fat depot, and a variety of other factors. Generally, pork fat is less saturated than lamb or beef, but more saturated than fish or poultry. As mentioned above in the Section Growth and Carcass Composition, gilts tend to be leaner than barrows and thus usually have greater iodine values. It is also well known that fatty acid profiles of pigs are directly influenced by diet. Feed ingredients that are high in polyunsaturated fat will increase the polyunsaturated fatty acid concentration of pork fat and increase the iodine value of various depots. Increasing the dietary consumption of linoleic acid (an unsaturated fatty acid) during the last 6–8 weeks before harvest increases the calculated iodine value of backfat in finishing pigs. Finally, pigs tend to deposit fat anatomically

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from the head and tail end toward the visceral cavity. So, as pigs reach physiological maturity, they begin to deposit fat in the jowl and shoulder region earlier in their growth curve than they deposit fat in the loin and belly area. In some parts of the world, the belly is the most valuable primal component of pork carcasses. Pigs bellies can be as much as 40% fat. So, it is important for packers to understand how diet and sex can influence fat quality and quantity. Soft, oily bellies are more difficult to slice and ultimately reduce the yields of salable products that can directly influence profits. Fat quality at all stages of pork production is quickly becoming of major interest to scientists because of its direct link to bacon processing. Leaner pigs have a greater percentage of lean, greater percentage of moisture, and a greater proportion of PUFA relative to fatter pigs. All of these things can lead to soft, oily bellies and reductions in bacon yield. Allowing pigs to become adequately fat (in markets that value bacon) will reduce slice yield variation and increase total bacon yield.

See also: Animal Breeding and Genetics: DNA Markers and Marker-Assisted Selection in the Genomic Era; Traditional Animal Breeding. Meat, Animal, Poultry and Fish Production and Management: Antibiotic Growth Promotants. Nutrition of Meat Animals: Pigs

Further Reading Aberle, E.D., Forrest, J.C., Gerrard, D.E., Mills, E.W., 2012. Principles of Meat Science, fifth ed. Dubuque, IA: Kendall/Hunt Publishing. AOCS, 1998. Official Methods and Recommended Practices of the AOCS, fifth ed. Champaign, IL: American Oil Chemist Society. Apple, J.K., Rincker, P.J., McKeith, F.K., et al., 2007. Review: Meta-analysis of the ractopamine response in finishing swine. Professional Animal Scientist 23, 179–196. Averette Gatlin, L., See, M.T., Hansen, J.A., Sutton, D., Odle, J., 2002. The effects of dietary fat sources, levels, and feeding intervals on pork fatty acid composition. Journal of Animal Science 80, 1606–1615. Boler, D.D., Dilger, A.C., Bidner, B.S., et al., 2010. Ultimate pH explains variation in pork quality traits. Journal of Muscle Foods 21, 119–130. Boler, D.D., Kutzler, L.W., Meeuwse, D.M., et al., 2011. Effects of increasing lysine on carcass composition and cutting yields of immunologically castrated male pigs. Journal of Animal Science 89, 2189–2199. Briskey, E.J., 1964. Etiological status and associated studies of pale, soft, exudative porcine musculature. Advances in Food Research 13, 89–178. Correa, J.A., Gariépy, C., Marcoux, M., Faucitano, L., 2008. Effects of growth rate, sex and slaughter weight on fat characteristics of pork bellies. Meat Science 80, 550–554. Dikeman, M.E., 2007. Effects of metabolic modifiers on carcass traits and meat quality. Meat Science 77, 121–135. Dunshea, F.R., Colantoni, C., Howard, K., et al., 2001. Vaccination of boars with GnRH vaccine (Improvac) eliminates boar taint and increase growth performance. Journal of Animal Science 79, 2524–2535. Hugo, A., Roodt, E., 2007. Significance of porcine fat quality in meat technology: A review. Food Reviews International 23, 175–198. Meadus, W.J., Duff, P., Uttaro, B., et al., 2010. Production of docosanhexaenoic acid (DHA) enriched bacon. Journal of Agriculture and Food Chemistry 58, 465–472. Monin, G., Sellier, P., 1985. Pork of low technological quality with a normal rate of muscle pH fall in the immediate post-mortem period: The case of the Hampshire breed. Meat Science 13, 49–63. Pauly, C., Spring, P., O'Doherty, J.V., Ampuero Kragten, S., Bee, G., 2009. Growth performance, carcass characteristics and meat quality of group-penned surgically castrated, immunocastrated (Improvac®) and entire male pigs and individually penned male pigs. Animal 3, 1057–1066.

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Scheffler, T.L., Park, S., Gerrard, D.E., 2011. Lessons to lean about postmortem metabolism using the AMPKγR200Q mutation in the pig. Meat Science 89, 244–250. Shackelford, S.D., King, D.A., Wheeler, T.L., 2011. Development of a system for classification of pork loins for tenderness using visible and near-infrared reflectance spectroscopy. Journal of Animal Science 89, 3803–3808. Stein, H.H., Surshon, G.C., 2009. Board-invited review: The use and application of distillers dried grains with solubles in swine diets. Journal of Animal Science 87, 1292–1303. Wood, J.D., Richardson, R.I., Nute, G.R., et al., 2003. Effects of fatty acids on meat quality: A review. Meat Science 66, 21–32.

Relevant Websites http://www.fda.gov/downloads/AnimalVeterinary/Products/ ApprovedAnimalDrugProducts/FOIADrugSummaries/ucm117251.pdf FDA. http://www.fda.gov/downloads/AnimalVeterinary/Products/ ApprovedAnimalDrugProducts/FOIADrugSummaries/UCM260401.pdf FDA. http://www.ams.usda.gov/mnreports/lswwklyblue.pdf United States Department of Agriculture (USDA).

Poultry P Mozdziak, North Carolina State University, Raleigh, NC, USA r 2014 Elsevier Ltd. All rights reserved. This article is a revision of the previous edition article by P Mozdziak, volume 3, pp 1296–1302, © 2004, Elsevier Ltd.

Introduction Poultry refers to birds such as chickens, turkeys, ducks, pheasants, geese, ostrich, emu, quail, and related species that are used for commercial production of meat. Many breeds of these species exist in the wild, but in commercial production many different breeds have been replaced by crossing several breeds with different desirable characteristics to produce a single breed or to develop hybrid lines with optimal meat yield and production efficiency. The focus of this article will be to review the classic and current species of poultry possessing desirable eating characteristics, and the nutritive value of poultry meat. The meat from almost all birds is commercially available. This review focuses not only on chickens, turkeys, ducks, geese, but includes ratites, which are flightless birds with rudimentary wings and without a sternum.

Chickens Domestication of chickens began with red jungle fowl, which were raised in different regions of India and China approximately 1000 BC. However, the birth of the modern chicken industry in the US began in the early 1900s, when chicken production was characterized by small backyard flocks that were maintained to produce eggs for food or sold locally. The aged hens or roosters from the home flocks were cooked in pressure cookers and eaten only for a Sunday dinner or holiday meal. In the early to mid-1900s, there was no organized system for processing poultry, which made it impossible for poultry meat to be available for retail sale at grocery stores, but live birds could be purchased and processed at home. As the twentieth century progressed, large markets for poultry meat developed in the northeast and the poultry industry became a year-round enterprise with broiler (i.e., young meat-type chicken) production becoming concentrated in the southeast because of its warm climate, economical labor, and access to grain via rail and barge transportation. As the demand for white/breast meat increased in the 1950s, the chicken industry began to undergo vertical integration to bring control of the hatcheries, feed mills, growth facilities, and processing plants under a single corporate structure. Concurrently, the poultry companies ceased using dual-purpose (meat and eggs) breeds of chickens, and they began to breed and produce chickens specifically for meat production. In the early days of the meat chicken production industry, it was common to grow dual-purpose breeds or to mate a dual-purpose rooster such as a Rhode Island Red with a Barred Plymouth Rock (Figure 1) hen to produce male progeny that were barred like their mothers and female progeny that were nonbarred like their fathers. The cockerel (young male

Encyclopedia of Meat Sciences, Volume 3

chickens) could then be separated and raised for meat production and the pullets (young female chickens) could be kept as egg producers. However, to improve production, companies stopped using dual-purpose birds and developed separate lines of chickens to produce either meat or eggs. The meat chicken or broiler industry has traditionally used crosses between White Plymouth Rock and Cornish birds. Both breeds have a large body size, but Cornish birds tend to grow faster than White Plymouth Rocks. Although most commercial broilers originated from crosses between White Plymouth Rock and Cornish chickens, the broilers of the 1950s are very different from modern day broilers. A commercial broiler chicken from a 2001 genetic background takes approximately 42 days to reach a bodyweight of 2.6 kg, a carcass weight of 2 kg, and a Pectoralis thoracicus (breast muscle) percentage of bodyweight of approximately 15.8%. In comparison, a commercial broiler from a 1957 genetic stock reaches a bodyweight of 1.8 kg, a carcass weight of 1.2 kg, and a Pectoralis thoracicus percentage of bodyweight of approximately 8.6% at 84 days of age. The most economically important chicken and turkey muscle is the Pectoralis thoracicus, which is composed of predominantly white (or fast twitch) muscle cells. Modern selection has decreased the time to market weight, increased the total size of the chicken, and increased the size of the Pectoralis thoracicus relative to bodyweight. Overall, modern selection techniques have profoundly changed the size of the chicken breast muscle (Figure 2). Chicken has grown to be a popular meat product because the increases in production efficiency have led chicken to become a low cost, tasty alternative to traditional red meats, such

Figure 1 Barred Plymouth Rock–layer chicken. Photo Courtesy of Dr. James Petitte, North Carolina State University.

doi:10.1016/B978-0-12-384731-7.00080-5

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Figure 2 Broiler chickens. Photo Courtesy of Dr. Ken Anderson, North Carolina State University.

1957 Genetics

2001 Genetics

Figure 3 A ‘typical’ broiler chicken from a genetic background that was produced in 1957 (1957 Genetics). A ‘typical’ broiler chicken from a genetic background that was produced in 2001 (2001 Genetics). Both birds were killed at 42 days of age. Photo courtesy of Dr. Gerald Havenstein, North Carolina State University.

as beef and pork. Chicken has become a low cost product because modern selection and production techniques have reduced the time to produce a broiler chicken to approximately 6 weeks. More importantly, it is possible to manage large numbers of chickens on a single farm (Figure 3), lending poultry production to be very efficient and making it possible for the poultry industry to easily become vertically integrated. Almost every chicken produced in the US comes from contract growers who enter into partnerships with major poultry companies and who may supply the chicks that are grown on the farm. Therefore, the large corporation can determine the type and number of chickens grown, the feed provided to the animals, and all aspects of production. Subsequently, the same company buys the chickens from the growers, processes the chickens, and distributes the final product to the retailers. The vertical integration of chicken production almost eliminates the costly possibility of either an oversupply or shortage of chickens for the processor, and provides the opportunity for an efficient operation. Chicken consumption in the US was approximately 9.9 kg per person (carcass weight) in 1955, whereas in 2009 it was approximately 42 kg per person (carcass weight). The increase in chicken consumption has not only occurred because of its relatively low cost but also because chicken meat tends to have consistent quality. Chicken tends to have few inherent tenderness issues because the vast majority of chickens grown in the US and other countries for fresh consumption are harvested at a young age (approximately 6 weeks) when the

animals have low connective tissue levels. Furthermore, the normal rapid pH decline and rapid onset of rigor mortis (approximately 4 h) and subsequent ageing in poultry has made meat quality defects, such as cold-shortening or thaw rigor negligible issues. In particular onset of cold shortening occurs at a much lower temperature (approximately 2 °C) than for red meats, but rigor at elevated temperatures (if there is no stimulation) can still toughen meat. Electrical stimulation can be used and in fact can both enable early portioning without shortening and toughening thus enhancing tenderness, but is not commonly used. Meat quality problems in poultry tend to be related to a pink color in the normally white breast muscle or a pink color in processed meat products. Similarly, hemorrhaging during slaughter and bruising during processing also tend to be a quality problem. A pale soft exudative (PSE) condition has been described in chicken and turkey meat, but the biological basis for the PSE condition in poultry is not as well understood as PSE condition in pork. The advent of new chicken products (chicken bologna, chicken nuggets, chicken hotdogs, and chicken wings) throughout the 1980s and the 1990s that are not only tasty but also convenient to prepare has fueled an increase in poultry consumption. The new chicken convenience foods have been successfully marketed for consumption at home and in the growing fast-food industry. However, one of the greatest reasons for the growth in chicken consumption may be the perception by health conscious consumers that chicken is a low-fat high protein source of healthy nutrition (Table 1).

Turkeys Domestication of the turkey may have begun with the Mayas in Mexico and Central America, and there are two different subspecies of turkeys found in the wild. One subspecies is found in Mexico/Central America, whereas the other is found native to the US. The variety found in the US is large, has a characteristic bronze plumage, and it is likely that the commercial lineage of domestic turkeys arose from the turkeys native to the US. The current standard breeds of turkeys are the Broad Breasted Bronze, White Holland, Naragansett, Black, Bourban, Royal Palm, and Slate. The White Holland was the only commercial white turkey during the early twentieth century. Much of the success of the modern turkey industry lies with the Broad Breasted Bronze whose rapid growth rate made it an exceptional animal for turkey meat production. Modern turkey production uses a large white breed (Figures 4 and 5), which was likely developed from the Broad Breasted Bronze and the White Holland breeds. Modern turkey production/consumption has undergone as great or greater increase than chicken production over the past 50 years, and the turkey industry has also undergone vertical integration. Similar to chickens, modern selection techniques have greatly changed the turkey over the last half of the twentieth century. In the late 1950s, tom turkeys were marketed at approximately 10.5–11.3 kg live weight. However, it took nearly 25 weeks for a tom turkey to reach approximately 11.3 kg in 1960, approximately 21 weeks to reach the same weight in 1974, and only approximately 28 weeks to reach 15.8 kg. In 2011, an achievable performance goal for a tom

Species of Meat Animals | Poultry Table 1

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Nutrient composition of various poultry meats data for beef and pork are provided for comparison

Data for 100 g edible portion

Calories

Protein (g)

Fat (g)

Cholesterol (mg)

Iron (mg)

Chicken breast meat only, raw Chicken breast meat and skin, raw Chicken leg meat only, raw Turkey breast meat only, raw, fryer-roaster Turkey breast meat and skin, raw Turkey leg meat, raw fryer roaster Duck meat only, raw Goose meat only, raw Ostrich round, raw Ostrich, tenderloin, raw Pork, fresh, composite of trimmed retail cuts (loin and shoulder blade), separable lean and fat, raw Pork, fresh, composite of trimmed retail cuts (loin and shoulder blade), separable lean only, raw Pork, fresh, loin, tenderloin, separable lean and fat, raw Pork, fresh, loin, tenderloin, separable lean only, raw Beef, tenderloin, separable lean and fat, trimmed to 3.25 mm fat, Choice, raw Beef, tenderloin, separable lean only, trimmed to 3.25 mm fat, Choice, raw Beef, composite of trimmed retail cuts, separable lean and fat, trimmed to 3.25 mm fat, Choice, raw

114 172 120 111 157 108 135 161 116 123 177

21 21 19 25 22 20 18 23 22 22 20

3 9 4 1 7 2 6 7 2 3 10

64 64 91 62 65 84 77 84 71 80 65

0.4 0.7 0.8 1.2 1.2 1.8 2.4 2.6 3.5 4.9 0.7

144

21

6

60

0.9

120 109 246

21 21 20

4 2 18

66 65 85

1.1 1.0 1.4

158

22

7

66

1.6

243

19

18

66

1.9

Source: Reproduced from US Department of Agriculture, 2011. Agricultural research service. USDA nutrient database for standard reference, release 24. Nutrient data laboratory home page. Available at: http://www.ars.usda.gov/main/site_main.htm?modecode=12−35−45-00 (accessed 15.10.13).

Figure 4 Typical young production turkey hens. Photo Courtesy of Dr. Ken Anderson, North Carolina State University.

Figure 5 Turkeys (typical) grown on range. Photo Courtesy of Dr. Ken Anderson, North Carolina State University.

turkey to reach 11.3 kg of live weight was 13 weeks of age, and a 22 week-old tom turkey to reach 22 kg of live weight. Therefore, modern selection has significantly altered the quantity, proportionality, and muscularity of turkeys, and rate of turkey muscle development. Overall, turkey carcasses have a high muscle to bone ratio, the breast meat accounts for approximately 29% of the carcass weight, and there is a high dressing percentage (475% live weight). However, selection for rapid growth has caused some problems for modern turkeys because the size of the breast muscle precludes mating and focal myopathy, which is a pathological muscle condition characterized by enlarged muscle cells, in the breast muscle has been reported to be associated with the rapid growth of these fascinating birds.

In concert with the improvement in the turkey production efficiency were also increases in turkey meat consumption. Till the late 1970s, turkey consumption was heavily concentrated at holiday festivals with very little consumption during the remainder of the year. However, because of aggressive marketing programs and the advent of new products, turkey has become a year-round meat product that American consumers enjoy on a daily basis. Per capita US turkey consumption was approximately 2.25 kg in 1955, but it rose to nearly 8 kg in the late 1990s, and the 2008 per capita consumption was approximately 8 kg and consumption has remained flat. The growth of the turkey industry can be tied to the relatively low cost of turkey meat, the advent of new turkey products (turkey bacon, turkey bologna, turkey hotdogs, sliced turkey breast,

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and turkey ham), and the perception by health conscious consumers that turkey is a healthy food. Furthermore, turkey meat is low in fat, high in protein (Table 1) and versatile.

Ducks Wild Mallard ducks are generally regarded as the ancestor of all breeds of domestic ducks. The Pekin is likely the most popular breed of duck that is used in commercial production. The Pekin undergoes early maturity, is hardy, and develops a good carcass. Pekin ducks originated in China during ancient times, and they were first imported to America after a lengthy sea voyage from Peking China in 1874. A young duck or duckling (usually under 8 weeks of age) has dark, tender meat, and weighs approximately 1.6–2.25 kg. The duck industry in the US was initially concentrated on Long Island, New York to supply the New York City market. However, the duck production industry in the US has shifted from its original Long Island base to be concentrated in the mid-western US, and the duck industry now enjoys a nation-wide market in the US. The single largest company producing ducks in the US has facilities in California, Wisconsin, Indiana, and Michigan producing 14 million ducks per year. Overall, the duck industry in the US is still much smaller than the chicken or turkey industries. It produces approximately 24 million ducks annually compared to approximately 8 billion chicken, and approximately 275 million turkeys. Similarly, the average American only consumes approximately 0.15 kg of duck per year making duck much less popular with American consumers than other poultry meat species. The largest duck producing nation is China (approximately 2.6 million metric tons), followed by France, Thailand, Vietnam, and the US (approximately 50 000 metric tons). Although it appears that duck meat is consumed on a world-wide basis, it tends to be less popular world-wide than chicken or turkey meat. The appeal of duck meat to American consumers tends to be in affluent specialty markets for people who prefer the taste of duck to turkey or chicken. Duckling is an international mealtime favorite, and it is best known for the elegant dishes prepared in elite restaurants, such as Peking Duck and Duck al’ Orange. However, there are a number of delicious duck recipes that are easy to prepare at home, such as Bar-B-Q duckling, roast duckling, and duckling pasta. Duck breast meat does not appear as white as turkey or chicken meat, and it is marketed as a ‘red’ meat. Duck meat is nutritionally similar to other poultry meats, except it appears that skinless duck meat has a higher fat content than skinless chicken or turkey meat (Table 1). A potential reason for the limited growth of the duck industry may be that duck tends to be much more expensive than chicken or turkey, or it may simply be related to the high cost of duck compared to all other food. Similarly, the convenience food, such as chicken nuggets, sliced turkey breast, chicken hotdogs, and turkey burgers, have not been produced or successfully marketed by the duck industry.

Geese The popular geese breeds are the Embden, Toulouse, African, Chinese, Pilgrim, Egyptian, and Diepholz. The development of

modern geese breeds has not followed the same path as modern chickens or turkeys, because goose production has not achieved the same corporate scale as the chicken or the turkey industry. Therefore, few industrialized breeding programs have been implemented for geese. The number of geese in Europe has dropped steadily since the introduction of modern poultry production techniques during the early twentieth century. An increases in geese production have occurred in less developed countries where geese can free range, live independently, and produce culturally acceptable, tasty meat. A major country producing goose meat is China. The barriers to geese playing a role in large-scale agriculture are the relatively poor reproduction rate, their slow growth rate compared to chickens and turkeys, and the lack of corporate marketing. Nutritionally, skinless goose meat is similar to other poultry meat species, but it contains a higher caloric fat and iron content than skinless chicken or turkey meat (Table 1). Overall, goose meat is a highly nutritious product that is an excellent source of protein for people in developing countries or consumers in more developed countries who enjoy its taste.

Ratite The US ratite (ostrich, emu, and rhea) industry began in the early 1980s as an almost totally breeder-production system. Bird prices were very high and the ratite market quickly reached a saturation point. The present ratite industry has shifted from a breeder-based industry to be a product-based industry (meat, hide, oil, and feathers), but the limited infrastructure of ratite-processing facilities has been a major barrier to the development of the industry. There are limited statistics available for ratite production, but there are likely between 50 000 and 100 000 ostriches and between 50 000 and 100 000 emus in the US. In Canada, there were only 11 ostrich, emus, or rhea harvested in 1993, whereas in 1997, there were 13 000 birds harvested. Therefore, some growth has occurred in the North American ratite industry during the 1990s, but there has not been a strong demand for ratite meat by North American consumers. Subsequently, there has been a steady decline in the number of Canadian farms producing ostrich and emus as well as a steady decline in total Canadian ostrich/emu numbers between 1996 and 2006 suggesting that the ratite industry has failed to develop in North America. The ostrich is indigenous to Africa, and it has been raised domestically in Africa since the 1800s. Ostriches stand up to 3 m high and can weigh 180 kg. Normally, ostriches are processed at approximately 10–14 months of age. Emus originated in Australia, and they are smaller than ostriches standing approximately 1.5 m high and weighing approximately 54 kg. Lastly, rheas are indigenous to South America, and they stand approximately 1.5 m high and weigh approximately 27–36 kg at maturity. All three species have organized associations to support the marketing of their products. The current market for ratite has been primarily for specialty meats, focusing on customers who wish to enjoy a tasty, low fat alternative to traditional red meat products. Consumer taste panels have only found slight differences in palatability attributes between ostrich steaks and Choice beef top loin steaks; however, the slight differences in palatability

Species of Meat Animals | Poultry did not significantly affect overall acceptability of ostrich steaks. Ostrich meat is very high in protein, but low in lipid content (Table 1). The nutrient composition of ostrich meat is similar to other poultry meats, but the sensory attributes are similar to traditional red meat. Overall, it has been difficult to introduce new meat products to American consumers, and demand for ratite meat failed to be firmly established. Any future success of the ratite meat industry in the US may depend on an effective distribution, marketing, and promotion strategy that have been characteristic of the broiler and turkey industries.

Game Birds The US game bird industry raises millions of birds to stock land for recreational hunting, sale to restaurants, and sale directly to consumers. Wild game legally hunted in the US cannot be sold to consumers, but the game can be harvested for personal consumption. Wild game that is raised on farms and processed under appropriate regulations can be sold to the consumers. In general, a large portion of the game bird industry is focused on hobbyists raising home flocks, and also on raising game birds to stock hunting grounds. Therefore, game birds, such as pheasants and Bobwhite quail, can be marketed as day-old-chicks for the small flock hobbyist, as young mature birds to stock hunting lands, and as meat for restaurants or the home consumer. In the US, up to 10 million pheasants, and 37 million quail are raised for consumption. Pheasants reach approximately 1.2 kg by approximately 16 weeks of age. A major obstacle to pheasant production is cannibalism, which is prevented by beak trimming, and the pheasants need their wings clipped to prevent flight. Quail are raised in similar conditions to broiler chickens, but they are very small birds making each require little floor space, and they reach market age by approximately 7 weeks of age with a carcass of 0.2 kg. Overall, the poultry industry provides a variety of tasty products, such as ratite, duck, quail, and pheasant for consumers who wish to explore the exotic meats, but these speciality products are vastly overshadowed by the larger scale production and consumption of lower cost broiler and turkey meat.

See also: Genome Projects: Modern Genetics and Genomic Technologies and Their Application in the Meat Industry − Red Meat Animals, Poultry. Human Nutrition: Macronutrients in Meat; Micronutrients in Meat. Meat, Animal, Poultry and Fish Production and Management: Antibiotic Growth Promotants; Beta-Agonists; Poultry. Muscle Fiber Types and Meat Quality. Nutrition of Meat Animals: Pigs; Poultry. Slaughter-Line Operation: Poultry

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Further Reading Agriculture and Agri-Food Canada, 1999. Snapshot of the Canadian Ostrich, Emu, and Rhea Industries. Agriculture and Agri-Food Canada, Marketing and Industry Services Branch, Agricultural Industry Services Directorate. Animal Industry Division, Poultry Section. Ontario. Chilliwack Agricultural Commission, 2002. Games birds. Description of specialty bird industry. Chilliwack, BC, Canada: Chilliwack Partners Commission. 23 January. Damron, W.S., 2002. Introduction to animal science: Global, biological, social, and industry perspectives. Saddle River, NJ: Prentice Hall. Economic Research Service (ERS), 2008. Food Availability (Per Capita) Data System. US Department of Agriculture (USDA). Available at: http://www.ers.usda.gov/Data/ FoodConsumption (accessed Mar 2013). Food Safety and Inspection Service (FSIS), 2008. US Department of Agriculture (USDA). Fact Sheets. Game from Farm to Table http://www.fsis.usda.gov/ factsheets/Farm_Raised_Game/index.asp#3. Food and Agriculture of the United Nations Statistical Database, Home Page. Available at: http://apps.fao.org/ (accessed Mar 2013). Gillipespie, J.R., 2002. Modern Livestock and Poultry Production, sixth ed. Clifton Park, NY: Delmar Publishers. Harris, S.D., Morris, C.A., Jackson, T.C., et al., 1994. Ostrich Meat Industry Development. Final Report to American Ostrich Association. Texas, USA: Texas A&M. Havenstein, G.B., Ferket, P.R., Qureshi, M.A., 2003. Growth, livability, and feed conversion of 1957 versus 2001 broilers when fed representative 1957 and 2001 broiler diets. Poultry Science 82, 1500–1508. Havenstein, G.B., Ferket, P.R., Qureshi, M.A., 2003. Carcass composition and yield of 1957 versus 2001 broilers when fed representative 1957 and 2001 broiler diets. Poultry Science 82, 1509–1518. Hugo, S., 1999. Geese: The Underestimated Species. FAO Report. Texas, USA: Texas A&M. Richard, R.I., Mead, G.C. (Eds.), 1999. Poultry meat science. New York: CABI Publishing. Sosnicki, A.A., Cassens, R.G., Vimini, R.J., Greaser, M.L., 1991. Histopathological and ultrastructural alterations of turkey skeletal muscle. Poultry Science 70, 349–357. Statistics Canada, 2008. Alternative livestock on Canadian farms, census years 1981, 1986, 1991, 1996, 2001, and 2006. Catalogue no. 23-502-X. Available at: http:// www.statcan.gc.ca/pub/23−502-x/23−502-x2007001-eng.pdf (accessed 15.10.13). US Department of Agriculture, Agricultural Research Service, 2011. USDA nutrient database for standard reference, release 24. Nutrient data laboratory home page. Available at: http://www.ars.usda.gov/main/site_main.htm?modecode=12−35− 45-00 (accessed 15.10.13).

Relevant Websites http://aea-emu.org/ American Emu Association. http://www.meatscience.org/ American Meat Science Association. http://www.ostriches.org/ American Ostrich Association. http://en.aviagen.com/tech-center/ Aviagen Group. http://www.nationalchickencouncil.org/ National Chicken Council. http://www.eatturkey.com/home.html The National Turkey Federation. http://www.uspoultry.org/ US Poulty and Egg Association.

Sheep and Goats EL Walker and MD Hudson, Missouri State University, Springfield, MO, USA r 2014 Elsevier Ltd. All rights reserved. This article is a revision of the previous edition article by EP Berg, EL McFadin Walker, volume 3, pp 1291–1295, © 2004, Elsevier Ltd.

Glossary Average daily gain (ADG) A measure used to compare growth rates of animals. Cabrito A name given to meat from milk-fed kids. It is similar in meaning to veal in cattle. Callipyge ‘Beautiful buttocks.’ A genetic mutation found in sheep associated with muscle hypertrophy, typically seen in the leg. Carcass composition The combination of, and relationship between, lean, fat, and bone present in the carcass.

Carcass quality Meat tenderness, juiciness, color, and flavor. Chevon Generic name for goat meat. Cold shortening A phenomenon that results in decreased tenderness of meat due to rapid heat dissipation from carcasses in the hours following slaughter. Small ruminant A term that denotes both sheep and/or goats. Small ruminants have a multicompartment pregastric digestive system similar to that of cattle and buffalo.

Introduction

World Sheep and Goat Inventory

Small ruminants, such as sheep (Ovis aries) and goats (Capra hircus), were among the first animals to be domesticated, with historical evidence linking them to western Asia approximately 9000–12 000 years ago. Domesticated sheep and goats provided early humans with a supply of fiber, pelt, meat, and milk. Owing to their small stature and versatility, small ruminants were, and still are, an important food source in dry, remote regions of the world that lack electricity and have limited grain or roughage. Small ruminants are also efficient convertors of low-quality feed materials to high-quality protein. Furthermore, a small ruminant carcass can be consumed in a few days, which allows only limited time for spoilage. Unlike sheep, which descended from four distinct types of wild sheep, including the Urial, Argali, Mouflon, and Aoudad, most goat breeds can be traced back to only one wild type, the Benzoar of Asia Minor and the Middle East. There are more than 850 breeds of sheep and more than 500 different breeds of goats worldwide. Although many believe that sheep and goats are similar in their physiological traits and behavior, they are quite dissimilar and should be treated separately. As large ruminants, such as cattle, and small ruminants are researched and managed differently, the sheep and goat should also be evaluated independently. Since the 1960s, meat consumption has increased worldwide following the increase in human population and greater disposable income in developing countries. Production of small ruminants could be increased in developing countries, if it were not for limited feed, lack of veterinary assistance and educational resources, and climatic challenges. In many areas of the world, including the USA, sheep and goat production tends to be thought of as low-investment, low-output enterprises. However, in many countries, these animals could generate greater income for producers, if it were not for a complicated system of government subsidies and regulations.

Between 2004 and 2007, the areas of the world most noted for sheep and goat production included China (143.8 million; home to one-third of all small ruminants), India (182 million), Australia (99.3 million), Iran (54 million), the Sudan (47 million), and New Zealand (40 million). Total worldwide production of small ruminants was approximately 2 billion head (1.25 sheep for every 1 goat), yielding more than 11.8 million metric tons of product. More than 90% of the world's goats and almost 70% of the world's sheep are in Asia and Africa. Australia produces more than 50% of the world's exported goat meat. The total number of goats worldwide has increased 146%, whereas production has doubled since 1990; in contrast, sheep numbers have decreased 10% since 1990. Although sheep meat has increased in value, the consumption of sheep meat has increased 36% from 2010 to 2011, which is greater than both beef (18%) and poultry (16%). The number of small ruminants worldwide has increased due to high fertility rates, frequency of multiple births, short generation interval, low-cost management, and opportunity for short-term return on investment. People living in rural areas with marginal land and poor economic opportunities can raise small ruminants, which improves income potential and the opportunity for consumption of quality protein. Since 2006, government restrictions in China and adverse weather conditions worldwide have slowed the population growth of small ruminants. Some countries, such as Australia, are trying to restock their breeding inventories, but elevated sheep and goat meat prices have encouraged the sale of live animals into the slaughter market. Small ruminants do well in a variety of climates. In general, sheep do better than goats in colder climate, whereas goats do better in rugged areas where brush and shrubs are the predominant forage types. Both can thrive on marginal lands and in areas that are unsuitable for cattle or buffalo and are more

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Species of Meat Animals | Sheep and Goats efficient than larger ruminants at converting forage into useable product. Except for dairy animals, sheep and goats have lower dietary requirements than larger livestock.

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Australia, and the USA to improve meat quality of feral goats. Boer goats have superior growth and carcass quality compared with many other breeds; however, research indicates that Kikos can wean more and heavier kids than Boers.

Biological Types of Sheep Domestic sheep are found in nearly every country throughout the world and are highly sought after for their wool, hides, and carcasses. Breeds, or biological types, of sheep can be broadly classified into five general types: ewe/wool, ram/carcass, dual purpose, milk, and hair breeds. Ewe/wool breeds, such as Rambouillet, Merino, and Finn, are noted for their maternal characteristics and/or high-quality wool. Ram breeds (e.g., include Suffolk, Hampshire, and Dorset) tend to excel at growth and carcass traits. Dual-purpose breeds, such as the Targhee and Columbia, are productive at two or more traits (e.g., wool and meat). The East Friesian is the world's highestproducing dairy breed, producing 500–700 kg of milk per lactation with 6–7% milk fat. Hair breeds shed, and thus do not have to be shorn, and are noted for their maternal or carcass qualities. Some hair breeds are also noted for their tolerance to parasites and overall vigor, making them popular in both tropical and temperate climates. Popular hair breeds include the St. Croix, Dorper, Barbados Blackbelly, and Katahdin. Selection of a particular breed depends on the breed's suitability to the production environment and its ability to meet the social and economic needs of the community. In areas of the world possessing a moderate climate, sheep breeds are often medium framed, of a compact conformation, with short legs and thicker wool. The average breed type in tropical regions has longer body and legs, longer ears and tails, and possesses short hair, as opposed to wool. The biological type chosen in arid regions that have a limited or seasonal supply of forage are often described as ‘fat-tailed’ breeds. Fat-tailed sheep, such as the Karakul, utilize the large stores of fat in their tail and hind-saddle region to sustain them through periods when food and water are limited.

Biological Types of Goats Goats can be sorted into fiber, milk, meat, or feral/brush types. The two most popular fiber breeds or breed types are the Angora and Cashmere (the latter of which is a breed type, not a particular breed). Although any goat can be used for milk production, popular milk breeds include the Alpine, Nubian, and Majorera. Meat breeds vary in type and kind and can include small breeds such as the Pygmy and large breeds such as the Boer. Feral/brush types include the Spanish (breed type) found in West Texas and the Kiko of New Zealand (before genetic improvements). In many areas of the world, breeds of goats are indiscernible and often exist in a feral state. Like sheep, selection of a goat breed for any one particular region of the world is based on the inherent traits of that animal in conjunction with the environment and the specialized needs of the populace. Of particular note is the Boer, which was developed in South Africa and is being used in countries such as China,

Factors Affecting Growth, Carcass Composition, and Carcass Quality Growth Effects of Breeds and Genetics on Growth Growth traits such as weaning (20% heritable) and postweaning (40% heritable) weights are used for selecting carcass quality and quantity. Carcass traits are moderately to highly heritable (30–60%), thus selection for superior growth and carcass traits can be used for increasing meat production. However, in the quest for increasing growth, it is important not to overlook fertility and efficiency traits. In addition, some genetic traits, such as growth rate and wool/hair production, are negatively correlated, and as more emphasis is placed on growth, fiber production and/or quality declines. If feed or capital resources are limited, it is not economically feasible to select for maximal growth.

Sheep Traditionally, ram breeds have been primarily used to increase growth in wool breeds. However, as wool becomes less valuable, hair breeds become more popular. Most hair breeds have decreased growth rates and average daily gain (ADG) compared with ram breeds. However, the Dorper, a hair breed originating from South Africa and comprised of the BlackHeaded Persian and the Horned Dorset, offers advantages in growth as compared with other hair breed types. More research is needed to understand differences in growth between hair, wool, and ram breeds.

Goats Goats typically produce smaller carcasses, even when slaughtered at similar ages or weights as sheep. Meat-type goats, such as the Boer, have greater ADG and yield heavier, meatier carcasses when compared with milk or feral breed types; however, Boers are not noted, at least in the USA, for possessing superior mothering or hardiness traits. Crossbreeding Boers with other breeds creates hybrid vigor, making the offspring superior than both parents in economically important traits.

Effects of management on growth Diet can significantly affect ADG, live and carcass weights, fat quantity and composition, and meat flavor. Animals on a high-energy diet grow faster and produce fatter carcasses than those on a forage diet. Animals on high-protein diets yield carcasses that consumers perceive as having ‘off ’-flavors compared with animals fed high-energy diets. Castrated sheep tend to grow slower than intact males, which is similar to results demonstrated in cattle and hogs. Studies with goats indicate that there is both a breed and time of castration effect on ADG; however, the results are conflicting with respect to age of castration. Some studies recommend early castration (less than 1 week of age), whereas others

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recommend delayed castration (after 6 months) for achieving most efficient growth in goats.

Carcass Composition Effects of breeds and genetics on carcass composition On an average, approximately 50% of live sheep/goat weight is retained as carcass weight. The carcass dressing percentage increases with increasing levels of fatness and/or muscularity. Dressing percentages typically range from 40% to 60%; however, extreme, heavily muscled animals may yield greater than 60% of their live weight as carcass weight. The weight of muscle tissue comprises 46–65% of the total dressed carcass weight. Sheep are intermediate to pigs and cattle for the propensity to deposit subcutaneous fat. Sheep produce carcasses with more dissectible fat and lean but with less bone than goats raised under similar management and slaughtered at similar ages and weight. Hair sheep may differ in the muscle– fat ratio; however, sufficient research has not been conducted to fully understand possible breed or type differences. Generally, it is thought that hair sheep deposit fat more like goats rather than like other sheep breeds. Small ruminants are sold for harvest as intact males, intact females, and wethers (castrated males). In some countries/ cultures, castration is either not permitted or consumers prefer meat from intact males. Carcasses from intact males typically have a thicker, more muscular neck and shoulders (adding weight to low-value cuts) compared with carcasses from females or castrated males. Depending on culture, these characteristics may be considered undesirable. The pelt of intact males is also more difficult to remove and may result in tearing of the external fat cover and a reduction in carcass appeal. Overall, breed and weight at the time of slaughter may have a greater effect on dressing percentage than gender. Goats deposit greater amounts of internal fat rather than subcutaneous fat when compared with sheep or cattle. Goat meat tends to be leaner than sheep meat and therefore has higher proportions of protein and minerals. Not much is known regarding growth or body composition of goats or hair sheep, especially when compared with wool and ram breeds of sheep, beef cattle, and swine.

Chemical profiles of sheep and goat meat Meat from lamb and goats is frequently touted as healthy. On an average, lamb contains 22% protein, 16% fat, and 78 mg of cholesterol per g of meat. Chevon contains, on average, 23% protein, 12% fat, and 94 mg of cholesterol per gram of meat. However, all of these values differ depending on preslaughter management and the particular cut of meat from which the sample was obtained. Animals slaughtered before six months of age tend to have lesser amounts of cholesterol than older animals. Also, breed may influence cholesterol content, as meat from St. Croix lambs may contain greater amounts of cholesterol compared with other breeds and breed crosses. Although there are species and breed differences, in general, meat from sheep and goats has a high monounsaturated to polyunsaturated fatty acid ratio. However, feeding diets with a ruminally protected source of fat can produce a more favorable polyunsaturated to saturated ratio. Also, as animals

become fatter, the composition of fatty acids changes because the triglycerides, which increase with fatness, are more saturated. Diet can also affect the ratio of oleic, palmitic, and linoleic acids. In addition, some have reported that there is a difference in fatty acid profile between genders, with males having a greater proportion of palmitic acid. The predominant fatty acids isolated from lamb and goat meats are oleic (28– 44%), stearic (12–25%), and palmitic (16–23%) and are roughly in the same proportions as found in beef and pork. Proportions can differ depending on diet (milk fed vs. concentrate vs. forage), age, and breed.

Effects of Management on Carcass Composition Sheep Across all breeds and weights, carcasses from rams are the leanest and ewes are the fattest. Ram lambs tend to have the largest and the longest carcasses and possess larger loin muscles compared with ewes. Wether lambs are intermediate. Delaying castration or slaughtering ram lambs before puberty can increase the carcass lean to fat ratio.

Goats Few studies have evaluated the effects of gender on carcass composition in goats. Time of castration affects dressing percentage, and variations in timing may explain why there is limited agreement between the published studies. In most cases, goats are slaughtered either before or soon after puberty (4–8 months); therefore, the effects of the male sex steroids may not have had sufficient time to affect dressing percentage. The proportion of retail carcass cuts is also affected by gender; however, breed and age have greater effects on carcass composition.

Carcass Quality Carcass quality is commonly assessed for carcass conformation and indicators of potential eating satisfaction (palatability). It should be noted that carcass conformation has little relationship with palatability. Furthermore, the definition of quality in the eye of the consumer is much broader and includes not only palatability but also product appearance, nutrient density, and wholesomeness (freedom from pathogens). Sensory characteristics, such as flavor, aroma, juiciness, and tenderness, are influenced by breed, diet, gender, and pre- and postslaughter management. Small ruminants are consumed all over the world; one should, therefore, expect the perception of quality to be extremely diverse. Factors that influence the perception of quality include (but are not limited to) muscle texture, tenderness, flavor, fat content, fatty acid profile, water content, preslaughter nutrition, postslaughter handling, processing practices, level of sanitation, meat aging, refrigeration (or absence of refrigeration), and cooking methods.

Factors affecting meat flavor

Components of meat flavor are both fat and water soluble, but the water-soluble components are relatively similar across species and are the main reason why fat-free products taste similar across species. It is the fat component of meat that primarily

Species of Meat Animals | Sheep and Goats contributes to species differences in flavor. The total and ratios of fatty acids present (often referred to as the fatty acid profile) in the adipose tissue of lamb and chevon influence flavor perception by consumers. Forages contain a variety of odoriferous and reactive fat-soluble components that ultimately are deposited as flavor precursors in the muscle. These compounds can accumulate within adipose tissue over time and are perceived as either positive or negative meat flavors (depending on culture or geographical origin of consumers). These flavorinfluencing compounds are more prevalent in chronologically older animals and can contribute to the distinct flavor differences between young and old animals. Generally, as animal′s age, flavor intensity increases, often to the point of undesirability for many consumers. In some areas of the world it is common to harvest and consume intact males, the meat from which may be perceived as less tender with stronger flavor. In the USA, more than 80% of lambs marketed are finished on high-concentrate (predominantly corn) diets, yet, in many countries, lambs are fed 100% forage diets. Lamb consumers accustomed to corn-finished lamb perceive forage-finished lambs to have ‘lamby’ or ‘grassy’ flavors. Those accustomed to the more common worldwide production practice of pastureor forage-finished lambs find the corn-finished lamb to be mild, lacking in traditional lamb flavor, and too fat. Little research has been conducted regarding the effects of diet on sensory characteristics of goat meat.

Effects of breeds and genetics on carcass quality There are some notable differences between lamb and chevon with respect to the role of breed on carcass quality. Although lamb is rarely perceived as tough, biological (breed) type can influence tenderness. Hair breeds are generally regarded as yielding tougher meat compared with ewe breeds. Although it has not been evaluated, differences may exist between hair breeds. Furthermore, meat from lambs expressing the callipyge (double muscling) genotype is distinctly less tender compared with lamb from ‘normal’ carcasses, irrespective of whether it is from wool or hair breeds. Lambs of St. Croix breeding have been shown to produce a more palatable carcass when compared with wool or callipyge sheep. However, little research has been conducted comparing hair breeds with the other breed types in terms of overall carcass palatability. Sheep carcasses tend to be perceived as higher quality than goat carcasses, and meat breeds of goats, such as the Boer, tend to be perceived as having higher quality carcasses, based on hindleg circumference, than indigenous or feral- and milk-type goats. However, assessment of carcass quality is influenced by local custom and preference, so it is hard to define a universal standard for carcass quality in the goat. When similarly prepared, consumers generally prefer lamb over goat in terms of tenderness, juiciness, and overall palatability. Unfortunately, less is known concerning the effects of breed or breed type on carcass quality in goats. There are conflicting results regarding the effect of breed on carcass quality, with some reports showing small or no effects, whereas others report breed to be a significant factor in carcass quality traits. This represents another area in which additional research efforts are needed. Goat carcasses have greater collagen content compared with lamb carcasses, which results in greater toughness. How-

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ever, because chevon is leaner than lamb, mutton, or beef, consumers may overlook some of the negative palatability traits as a trade-off for a leaner protein source. Additionally, sheep and goats have less subcutaneous fat cover than pigs and cattle have; moreover, goats deposit less subcutaneous fat than sheep and yield leaner carcasses. Lean carcasses chill faster than ones with more fat cover, which may lead to cold shortening of muscle fibers and increased meat toughness. Rapid chilling of prerigor carcasses can also induce cold shortening of the muscle fibers and thus should be avoided. Cold shortening can be reversed by applying electrical stimulation to the carcass or by increasing the postmortem aging process, which may increase tenderness. This procedure shortens the time necessary for the onset of rigor mortis by accelerating postmortem glycolysis so that carcasses may be rapidly chilled without the risk of inducing cold shortening.

Effects of management on carcass quality Worldwide management practices favor production of small ruminants on a pastoral diet. Pasture-raised animals rarely become excessively fat. However, in countries where it is economically feasible to feed high-energy, corn-based diets, the potential for overfattening exists if animals are not properly managed. Those raised on high-energy diets tend to be tenderer, but fatter, than animals fed with low-energy diets. Little research has been conducted in goats to determine how diet affects overall carcass quality, including tenderness. In other meat animals, age at harvest affects tenderness; however, there is no consensus as to the effect of chronological age on lamb tenderness (lamb vs. mutton). The accumulation of connective tissue and the increased maturation of muscle of older lambs increase the potential for tougher meat. Early maturing, small-framed sheep (such as the hair breeds) reach an ideal lean to fat ratio earlier, and if fed to a harvest weight similar to large-framed breeds, they will possess too much fat. Later maturing, fast-growing sheep (often black-faced breed types) and goats (Boer or Boer type) tend to be more heavily muscled and should be marketed at an earlier chronological age to increase the lean to fat ratio. The age at which small ruminants are harvested depends on the demands of consumers. If consumers prefer larger cuts of lamb/goat, age at slaughter will increase to allow more time for increased muscle growth. However, without proper management, lambs/kids fed to heavier market weights reach a point of physiological maturity, at which increases in muscle mass slow or cease causing the animal to become excessively fat. Consumers usually avoid excess fat when purchasing lamb/goat. Animals slaughtered at an older age may also be perceived as less desirable by the consumer, in part due to darker meat color. In addition, due to enhanced proteolysis, older animals yield meat with flavor differences, which are often characterized as bitter tasting. An additional benefit of castration is to prevent taint of the meat, which is caused by androstenone, a steroid produced by the testes. Androstenone accumulates in the fat and is released when the meat is cooked. However, the perception of an undesirable sexual odor in meat is not consistent or well understood. Factors such as breed, season of rearing, age at castration, and age at slaughter all affect palatability traits of meat from

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intact males. Regardless of gender, lamb meat tends to be perceived as tender. In goats, does yield tenderer carcasses with greater marbling than intact males. Color is also affected by gender, with males generally yielding lighter lean tissue. In goats, differences between intact and castrated males have not been evaluated. However, gender does not influence muscling indicators, such as carcass or leg conformation scores, which are commonly used to assess carcass quality in goats.

Effects of postslaughter management on carcass quality Breed, genetic type (e.g., callipyge genetic condition), subcutaneous fat cover, and pre- and postslaughter handling may be more important factors affecting tenderness than chronological age in sheep or goats. Most sheep and goats are killed before 1 year of age, which decreases the amount of connective tissue growth, thus decreasing the chance of toughness. Consumers first assess leanness when determining their intent to purchase lamb. However, the evaluation of retail cuts of lamb for freshness, as perceived by color, is an important factor for consumers. There are contradictory assessments of meat color and presumed freshness; some consumers equate a bright red color with greater quality and freshness of the product, whereas others deem a darker red color as more acceptable. Like flavor, color preference is culturally and geographically specific. Potential consumers also perceive lamb meat color differently based on the manner of packaging. Meat color can also be influenced by factors that have little to do with the overall quality of the product, such as preslaughter management of live animals. Sheep exposed to prolonged periods of preslaughter stress, such as illness, poor nutrition, or prolonged transportation, often produce meat that is darker in color. Furthermore, these animals often yield carcasses with greater intramuscular pH that leads to an increased risk of premature spoilage.

Summary Small ruminants have been economically important to humans for thousands of years; because of this, more than 1000 breed types have been developed to fit various management practices and environmental conditions worldwide. Meat quality (palatability, nutrient density, wholesomeness, appearance) can be influenced by various factors, such as breed, gender, feeding regimen, and chronological age. There is no universally accepted method of assessing carcass composition and quality, because of worldwide differences in perception of what constitutes acceptable lamb/goat. Generally speaking, consumers of lamb and goat prefer a lean, lowfat product, but they disagree with regard to what is considered desirable palatability or flavor. Sheep and goats are inherently different animals, and thus they should be treated and researched as such.

Conversion of Muscle to Meat: Aging; Rigor Mortis, Cold, and Rigor Shortening. Double-Muscled Animals. Growth of Meat Animals: Adipose Tissue Development; Growth Patterns. Meat, Animal, Poultry and Fish Production and Management: Red Meat Animals. Modeling in Meat Science: Meat Quality. Nutrition of Meat Animals: Ruminants. Physical Measurements: Temperature Measurement. Sensory and Meat Quality, Optimization of. Slaughter-Line Operation: Sheep and Goats. Species of Meat Animals: Meat Animals, Origin and Domestication

Further Reading Bailey, M.E., Suzuki, J., Fernando, L.N., Swartz, H.A., Purchas, R.W., 1994. Influence of finishing diets on lamb flavor. In: Ho, C.T., Hartman, G.T. (Eds.), Lipid in Food Flavors. Washington DC: American Chemical Society, pp. 171–185. Bayraktaroglu, E.A., Akman, N., Tuncel, E., 1988. Effects of early castration on slaughter and carcass characteristics in crossbred Saanen × Kilis Goats. Small Ruminant Research 1 (2), 189–194. Berg, E.P., Neary, M.K., Forrest, J.C., 1998. Methodology for identification of lamb carcass composition. Sheep and Goat Research Journal 14 (1), 65–75. Beserra, F.J., Madruga, M.S., Leite, A.M., da Silva, E.M.C., Maia, E.L., 2004. Effect of slaughter age on chemical composition of meat from Moxotó goats and their crosses. Small Ruminant Research 55, 177–181. Burke, J.M., Apple, J.K., Roberts, W.J., Boger, C.B., Kegley, E.B., 2003. Effect of breed-type on performance and carcass traits of intensively managed hair sheep. Meat Science 63, 309–315. Cooper, S.L., Sinclair, L.A., Wilkinson, R.G., et al., 2004. Manipulation of the n-3 polyunsaturated fatty acid content of muscle and adipose tissue in lambs. Journal of Animal Science 82, 1461–1470. Guiterrez, A.N., 1986. Economic constraints on sheep and goat production in developing countries. In: Timon, V.M., Hanrahan, J.P. (Eds.), Proceedings of an Expert Consultation Small Ruminant Production in the Developing Countries. Sofia, Bulgaria: Agriculture and Consumer Protection. FAO Corporate Document Repository, pp. 138−147. Available at: http://www.fao.org/docrep/009/ah221e/ AH221E13.htm (accessed 19.12.11). Lawrie, R.A. (Ed.), 1998. Factors influencing the growth and development of meat animals. Lawrie's Meat Science, sixth ed. Lancaster, PA: Technomic, pp. 11–30. Lind, V., Berg, J., Eilertsen, S.M., Hersleth, M., Eik, L.O., 2011. Effect of gender on meat quality in lamb from extensive and intensive grazing systems when slaughtered at the end of the growing season. Meat Science 88, 305–310. Melton, S.L., 1990. Effects of feeds on flavor of red meat: A review. Journal of Animal Science 68, 4421–4435. Mitcham, S., Mitcham, A., 2000. Meat Goats: Their History, Management and Diseases. Sumner, IA, USA: Crane Creek Publications. Mottram, D.S., 1998. Flavour formation in meat and meat products: A review. Food Chemistry 62 (4), 415–424. Nsoso, S.J., Young, M.J., Beaton, P.R., 2000. A review of carcass conformation in sheep: Assessment, genetic control, and development. Small Ruminant Research 35, 89–96. Sande, D.N., Houston, J.E., Epperson, J.E., 2005. The relationship of consuming populations to meat-goat production in the United States. Journal of Food Distribution Research 36 (1), 156–160. Seideman, S.C., Cross, H.R., Smith, G.C., Durland, P.R., 1984. Factors associated with fresh meat color: A review. Journal of Food Quality 6, 211–237. Tshabalal, P.A., Strydom, P.E., Webb, E.C., de Kock, H.L., 2003. Meat quality of designated South African indigenous goat and sheep breeds. Meat Science 65, 563–570.

Relevant Websites See also: Boar Taint: Biological Causes and Practical Means to Alleviate It. Carcass Chilling and Boning. Chemical and Physical Characteristics of Meat: Adipose Tissue; Color and Pigment; Palatability; pH Measurement; Water-Holding Capacity.

http://www.fao.org/docrep/014/al981e/al981e00.pdf Breeds of Livestock Website Maintained by the Department of Animal Science at Oklahoma State University. http://www.ansi.okstate.edu/breeds/ FAO, November 2011. Food Outlook.

Species of Meat Animals | Sheep and Goats http://www.sheepandgoat.com/ Maryland Small Ruminant Page. http://www.lsuagcenter.com/NR/rdonlyres/B8FE3706-64DC-417F-A592B8DEC14B4D9F/43291/pub2951MeatGoatJanuary2008HIGHRES.pdf Meat Goat Selection, Carcass Evaluation & Fabrication Guide. http://www.ams.usda.gov/AMSv1.0/getfile?dDocName=STELDEV3060365 United States Standards for Grades of Lamb, Yearling Mutton, and Mutton Carcasses.

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www.wri.org World Resources Institute. 2002–2004 Earth Trends − The Environmental Information Portal Livestock Production Management − Demography of Sheep and Goat Population and Their Role in Economy.

Shellfish XM Vilanova, Universitat Autònoma de Barcelona, Barcelona, Spain r 2014 Elsevier Ltd. All rights reserved. This article is a revision of the previous edition article by LS Andrews, volume 3, pp 1317–1324, © 2004, Elsevier Ltd.

Introduction Shellfish are edible aquatic invertebrate animals, usually with a shell, including molluscs such as oysters, clams, mussels, and cephalopods and crustaceans such as shrimp or lobsters. This article presents the major species of shellfish consumed worldwide. It is divided by scientific classification and presented with the market and scientific names as well as a brief description of each. Those species of major economic importance and those of popular or regional consumption such as, ‘Louisiana crawfish,’ are described in more detail. Nutritionists value shellfish as a quality protein source. Seafood contains all of the essential amino acids, and with 17– 25% protein is an excellent source to meet our daily protein needs. Although shellfish tend to contain slightly higher amounts of cholesterol than finfish, the amounts for crab and lobster are similar to that in the dark meat of chicken. Cholesterol levels vary with shrimp species, but are generally 1.5−2 times higher than in other shellfish. Previously, shellfish were excluded from low-cholesterol diets because they were believed to be high in cholesterol. Today, with modern sophisticated measuring, it is known that cholesterol levels are lower than previously reported. Molluscs, such as clams, oysters, scallops, and mussels, have been found to have a large percentage of noncholesterol sterols that appear to have a positive effect on cholesterol levels. Shellfish are a rich source of essential minerals. Oysters and crustaceans are rich in zinc, iron, and copper; mussels, scallops, and clams are rich in potassium. All shellfish are good sources of iodine, phosphorus, and selenium. Shellfish eaten raw or cooked without added fat are low in fat (o5%) and calorie content.

Crustaceans or Crayfish

the names or relationships of actual taxa (Figure 1). Shrimp are caught or cultured in temperate and tropical salt waters and fresh waters, especially in China, Thailand, Ecuador, Indonesia, India, Bangladesh, and the Gulf of Mexico. World shrimp consumption has increased steadily since 1970. Wildcaught shrimp provided most of the world supply until the mid-1980s. The world catch is now more than 2 million tones, with 30% supplied from aquaculture. Common edible shrimp are presented in Table 1.

Lobster and Spiny Lobster Lobster is the common name for marine decapod crustaceans. The American and European lobsters are characterized by an enlarged pair of pincers or claws. Spiny lobsters (Figure 2) are not closely related to true lobsters and are distinguished from American and European lobsters by their long antennae and hard shell and are clawless. Spiny lobsters are also, especially in Australia, New Zealand, and South Africa, are sometimes called crayfish, sea crayfish, or crawfish, terms which elsewhere are reserved for freshwater crayfish. Lobster is considered a luxury seafood. Species of the common lobster are included in Table 2.

Crab Crab meat and claws are among seafood lover's favorite seafood. Crabs are found both on the Atlantic and Pacific coasts of North and South America and the western coasts of north and central Europe, with each region having a local favorite. Several of the world's favorite crab species are presented in Table 3 (Figure 3).

Crustacea, a Subphylum of Arthropoda, contains mostly marine arthropods, though many of its members, like crayfish, have invaded fresh water. In the sea, large crustaceans such as crabs and shrimp are common bottom-dwellers. Many minute species of crustaceans are important components of the zooplankton (floating or weakly swimming animals) and serve as food for other invertebrates, fishes, and even whales.

Shrimp/Prawn One of the world's most abundant and popular seafoods, shrimp contribute to the diets of cultures around the world. Shrimp and prawn are vernacular or colloquial terms and are terms of convenience, but one should not confuse them with

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Figure 1 Blue prawn. Reproduced with permission from L&S Farms, Photographer: Cortney Ohs.

Encyclopedia of Meat Sciences, Volume 3

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Species of Meat Animals | Shellfish Table 1

381

Common edible shrimp

Zoological name

Common name

Location

Properties/uses

Culinary attributes

Penaeus monodon

Black tiger

Central and SE Asia

Mild flavor

Penaeus stylirostris

Blues or Mexican whites

Pacific coast of Mexico

Penaeus aztecus Pandalus borealis

Browns Deep sea shrimp

SE USA; Gulf of Mexico Coast of northern Europe

Hymenopenaeus robustus

Gulf shrimp

Gulf of Mexico

Penaeus japonicus Aristeus antennatus

Kuruma or Japanese prawn Mediterranean prawn

Indo-Pacific area; Red and Mediterranean Seas Mediterranean Sea

Black with yellow striped tails Similar to Gulf of Mexico Whites Abundant, low cost Most are sold at local markets Large shrimp weighing ≤40 g Large prawns

Penaeus duorarum

Pink shrimp

Premium domestic US shrimp

Palaemon serratus

Premium shrimp of France and Italy

Firm texture and mild sweet flavor

Sicyonia brevirostris

Prawn/pink shrimp; sword shrimp; crevette rose; camaron or gamberellon Rock shrimp

Coastal USA in wide bottom sand or mud shelves Deep water Atlantic Ocean and Mediterranean Sea

Sold as appetizer or ‘starter’ in local markets Firm texture and mild sweet flavor

Small with a thick shell

Crangon crangon Panaeus setiferus

Sand shrimp Whites

Tropical variety found off the coast of Florida Coastal Europe Gulf of Mexico and SE USA

Texture and flavor similar to lobster Cooked whole Firm texture with nutty flavor

Blue or red varieties

Often served with oysters 30% of total US harvest

Firm texture and full, nutty flavor Softer texture than others Firm texture Firm texture Firm texture

than other commercial species and they turn a beautiful bright red when cooked. The meat has a firm texture and is generally considered more flavorful than shrimp. The hepatopancreas (called ‘fat’ by local consumers) is often consumed along with the meat and is used as a flavor ingredient in a variety of local recipes.

Procambarus zonangulu (White River Crawfish) White river crawfish are primarily harvested from northern and central Louisiana.

Figure 2 Spiny lobster. © Avril Bourquin.

Crayfish/Crawfish More than 400 species of crayfish are found worldwide. Only 3 of the 250 edible species are available commercially in North America. Crayfish live in freshwater rivers and streams, mostly in temperate climates. In North America, the crayfish is commonly called ‘crawfish.’ Most crawfish processing occurs in Louisiana, where they are caught wild and pond-raised. Crawfish are sold live for ‘crawfish boils’ or processed for frozen tail meat. Crawfish, like crabs, replace their hard shell during growth. During the ‘softshell’ period, the whole crawfish can be eaten and is considered a delicacy.

Pacifastacus leniusculus (Pacific Crayfish) Harvested in California and Oregon, they are consumed by local markets.

Krill (Euphausia superba) Krill is a tiny shrimp-like crustacean and is considered the most important zooplankton species associated with sea ice, playing a key role in the Antarctic food web. Krill travel in large swarms. Commercial fishermen harvest krill as a high-protein ingredient for value-added products and krill has recently been featured at various seafood shows throughout the world.

Molluscs Procambarus clarkia (Red Swamp Crawfish) Louisiana red swamp crawfish are harvested in the delta region. They are the most popular because of their larger size

Any member of the Phylum Mollusca, an invertebrate with a soft unsegmented body, usually protected by a shell in one, two, or three pieces. The molluscs include oysters, clams,

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Species of Meat Animals | Shellfish

Table 2

Common edible lobster

Zoological name

Common name

Location

Properties/uses

Culinary attributes

Jasus edwardsii and jverreauxi Panulirus llaevicauda

Australian rock lobster

Major import to the USA

Palinurus interruptus

California spiny lobster

Marketed frozen for broiling Marketed frozen for broiling Boiled whole

Homarus americanus

Canadian/American lobster

Homarus gammarus

European lobster

Palinurus mauritanicus

European spiny lobster

Palimurus argus

Florida spiny lobster, Caribbean lobster, rock lobster, or langouste Hawaiian spiny lobster

Coastal Australia and New Zealand Caribbean Sea; East coast of S America Southern coast of California Western Atlantic Ocean from Labrador to North Carolina Coasts of Great Britain, Norway and Brittany Mediterranean and E Atlantic Western tropical Atlantic from Florida to S America NW Hawaiian Islands Norway, E Atlantic coast of Europe and Adriatic and western Mediterranean Sea Tropical seas

Smaller than lobsters, with long, smooth bodies Small

Boiled whole

South Africa

Cape crayfish

Premium lobster

Panulirus marginatus

Brazilian spiny lobster

Nephrops norvegicus

Langoustines, Dublin Bay prawns, scampi

Scyllarus arctus

Slipper/squat lobster, or Australian ‘bug’ lobster South African rock lobster

Jasus lalandii

Table 3

Harvested for tail meat Mainly supplied local markets Weight range 0.9–2.2 kg; bright red shell Darker, bluish shell compare to American Thorny shell Rough, hard shell. Sold for local markets only Season limited by supply

Considered a delicacy in American and European markets; boiled live Flavor and texture same as American European delicacy Flavor and texture similar to American and European lobster Firm texture and sweet flavor Boiled whole

Common edible crab

Zoological name

Common name

Location

Properties/uses

Culinary attributes

Callinectes sapidus

Blue crab

Largest commercial crab fishery in the USA

Cancer magister

Dungeness crab

Niche market

Cooked and eaten whole or processed for meat and claws. Strong distinct flavor Cooked for local markets

Paralithodes camtschaticus

King crab or ‘red’ king crab

East Coast USA and S America, Gulf of Mexico, France, Holland, and Denmark Oregon and Washington states Alaska

Coldwater crabs. Have 6 legs and 2 claws, unlike other crabs with 8 legs and 2 claws

Firm texture; meat like lobster; legs are meatier and are preferred over the claws

P. brevipes

Brown or deep water king crab Southern king crab Snow crab

Smaller and less expensive than king crab Giant crab may reach 40 cm Stone crab claws are snipped off the live crab and will regenerate Distinguished by their extra pair of ‘paddlelike’ appendages

Legs are steamed or boiled

Lithodes antarcticus Chionoecetes oplio, C. bairdi, and C. tanneri Maia squinado Menippe mercenaria

Portunidae spp.

Spider crab, thomback crab Stone crab

Swimming crab, mud crab, shore crab, velvet crab

Deep water Alaska Chile to Antarctica Alaska

Europe and Japan Florida west coast

Italy, Portugal, Australia, and SE Asia

Steamed or broiled Claws are steamed and served cold Soft shell are a delicacy in China; used for Thai crab cakes and Scottish crab soup

Species of Meat Animals | Shellfish snails, slugs, squid, and octopuses. Most molluscs are aquatic but some land snails like Helix aspersa are also eaten. It is the snail most cultivated for gourmet food and is known as petit gris.

Bivalves (Two Piece Shells)

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communities, must be carefully monitored to ensure that they have not been contaminated with polluted water, especially during periods of heavy rain. Many species of oysters are harvested in small numbers and marketed for retail as exotic speciality oysters. The more important edible species are presented in Table 4 (Figure 4).

Oysters

Clams

Oysters have a rough, irregularly shaped shell and live mainly in temperate or warm coastal or estuarine waters. Oysters (often eaten raw) are considered a seafood delicacy. Raw oyster consumption is occasionally associated with gastrointestinal disease. Oyster beds, often located adjacent to rural

These burrowing shellfish are freshwater or marine molluscs having a muscular foot with which they can burrow into sand. More than 20 000 species are edible, but only approximately 50 species are harvested commercially. A few of these commercially available clams are presented in Table 5 (Figure 5).

Figure 4 True oysters. © Avril Bourquin.

Figure 3 Blue crab. © Avril Bourquin.

Table 4

Edible oysters

Zoological name

Common name

Location

Properties/uses

Culinary attributes

Crassostrea virginicus

Eastern Atlantic or American oyster

Eastern USA, Southern Canada, Gulf of Mexico

Thick rough shells; the most popular and plentiful oyster in the USA

Mild delicate flavor; often consumed raw

Ostrea edulis

Europe

Crassostrea gigas

Native or ‘flat’ oyster; French Belon, the English Whitstable, Colchester and Helford, the Irish Galway and the Belgian Ostendes Pacific or Japanese oyster

Crassostrea angulata Crassostrea commercialis Ostrea lurida

Fine texture and rich flavor. The Belons, grown in cold water, have a briny, metallic flavor

Pacific coasts of USA and Japan

Most widely farmed oyster in the world

Portuguese cupped oyster

France and Portugal

Farm raised

New South Wales Pacific coast USA

Ostrea chilensis

Sydney rock oyster Western Olympia oyster; American native Bluff oyster

Farm raised Small oyster less than 5 cm in length Dredged

Saccostrea commercialis

Rock oyster

Native to Chile and New Zealand New Zealand

Commercially grown originally but now supplanted by Pacific oyster

Very large size makes them highly suitable for cooking Considered a delicacy, spéciales claires Rich, fresh flavor Sold at local markets Sold at local markets Exported

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Table 5

Species of Meat Animals | Shellfish Common edible clams

Zoological name

Common name

Location

Properties/uses

Culinary attributes

Panopea generosa

Geoduck clam

Pacific coast USA

Mercenaria mercenaria and Mercenaria campechiensis

Hard clam; quahog

New England shores of USA

Large clam attaining an inshell weight of 4 kg Popular recreational fishery

Tapes philippinarium Arctica islandica

Manila clam Ocean quahog or ‘black clam’

Venerupis decussate

Palourde/carpet shell clam

Philippines N Atlantic Coasts from Europe to USA and Canada Southern Europe

Small clam

Venus verrucosa

Praire/warty Venus clam

Europe to Africa

Small clam

Ensis directus, Solen marginatus and Siliqua patula Mya arenaria

Razor or jackknife clam

Europe, California, Aleutian Islands

Long shape up to 25 cm

Steamed for delicate texture and flavor Marketed for steaming as chowder clams (large), cherrystone (medium), and ‘little neck’ (small) Satisfy a ‘niche’ market Comprise 38% of US clam market; light flavor with crisp texture Consumed raw in local markets Consumed raw in local markets Popular for ‘clam diggers;’ steamed in sandy pits

Soft-shell clam

A soft-shell clam with a long neck

Usually steamed

Spisula solidissima

Surf clam

North America, Europe, and Pacific coast of the USA Atlantic coast of N America from S Carolina north to the St Lawrence Gulf

A larger clam species

Processed as clams strips for breading and frying

Exotic species to USA Harvest estimates are 46 million annually

Mussels Mussels are distinguished by a blue–black shell and live attached to objects in the sea. The many varieties of mussels are harvested from cold Atlantic waters in both Europe and the US and off the coast of New Zealand.

Mytilus edulis (blue mussel)

Figure 5 Quahog clam. © Avril Bourquin.

Scallops Marine bivalve molluscs have a distinctive fanshaped shell with radial ribs and wavy edges. Scallops move by opening and closing their valves. Near the hinge where the two valves (shells) meet is the eye, or adductor muscle, which is the part of the scallop eaten in North America. In Europe, the entire scallop is eaten. More than 300 species of scallop occur worldwide, with varying shell color including beige, pink, salmon, and yellow. The more commonly consumed scallops are presented in Table 6 (Figure 6).

The blue mussel represents the dominant mussel species in North America. They are found in Atlantic waters from Canada to North Carolina. They have a smooth, bluish-black elongated shell. The inside of the shell is pearly violet or white. Between the shells on one side is a bundle of tough, brown fibers called the byssal threads or ‘beard.’ These fibers are used to anchor the mussel to rocks, pilings, and other mussels. As demand for consumption increases, wild populations are being supplemented by aquaculture to prevent depletion of natural beds. In Europe, blue mussels have been cultured for over 300 years. Mussels are efficient feeders compared to other shellfish. They have a third more protein than oysters. Orangetinted meats represent mature female mussels, whereas the ivory meats are males and immature females. Connoisseurs maintain that mature females have the best flavor.

Perna canaliculus (greenshell mussel) Greenshell mussels are harvested off the coast of New Zealand and may grow up to 23 cm.

Cockles (Cardium edule) Cockles are found worldwide but are traditionally thought of as a British speciality. In North America, they are known as ‘heart clams.’

Species of Meat Animals | Shellfish Table 6

385

Common edible scallops

Zoological name

Common name

Location

Properties/uses

Culinary attribute

Argopecten irradians

Bay scallop

Small scallop only 2 cm

Firm, white meat

Argopecten gibbus

Calico scallop

Important commercial species; 465 t annually

Firm, white meat

Chlamys opercularis

Queen scallop

N America: New England to Gulf of Mexico Tropical and subtropical Atlantic from N Carolina to Brazil SE Asia

Small scallop

Placopecten magellanicus

Sea scallop

Patinopecten cauimus

Weathervane scallop

Atlantic coast of N and S America Alaska

Pecten novaezelandiae

Scallop

New Zealand

Firm, white meat used in soups Distinct sweet odor when fresh Sweet, crisp flavor and texture Firm, white meat

Largest species, market size is 1.5–8 cm Short harvest season; 2–3 weeks in late summer Important commercial species; 747 t annually in 2004. Seeded from spat

widely in Chinese and Japanese cooking, can be purchased fresh, canned, dried, or salted. The iridescent shell is a source of mother-of-pearl. The wild fishery is carefully managed and abalone farms have been established to meet consumer demand.

Conches (Strombidae sp.) Of the numerous species of conches, the queen conch is the most popular edible species. They are mostly found near the breaking surf of barrier reefs because of their high oxygen requirement. Conches are harvested from Belize, Turks, and Caicos and the Bahamas for restaurant trade. The meat is white with a tough rubbery texture and is pounded to tenderize it. Because of their rarity, conches bring a good price in restaurants.

Whelks (Subclass Prosobranchia, Buccinum undatum) Figure 6 Scallop. Reproduced with permission from Shells Database.

Single-Shell Molluscs Gastropods Gastropods have a head with eyes, a large flattened foot, and often a single shell. Gastropods are the largest class in the Phylum Mollusca and are the most diverse. Nearly 35 000 living species and 15 000 fossil species have been identified, including spirally coiled snails, flat-shelled limpets, shell-less nudibranchs, whelks, abalones, pteropods, and terrestrial snails and slugs. There are several varieties of Abalone (Haliotis cracherodii (black), Haliotis rufescens (red), and Haliotis iris (white)). Of all the gastropods, abalone is the most popular for human consumption. The red and black abalone are found along the coastlines of California, Mexico, and Japan. Approximately 100 species exist worldwide. The edible portion is the adductor muscle, by which it clings to rocks. Abalone, used

Prosobranchia (limpets, winkles, whelks, etc.) are familiar creatures, often found in rockpools on the seashore. The common whelk is distributed along Atlantic coasts, the English Channel, the North Sea, and the Baltic Sea. They inhabit sand and mud from shallow water to a depth of 100 m. Fully grown, whelks have a shell up to 10–15 cm high with a pointed spire and well-defined ribbed whorls. They are usually pale brown in color. The largest whelks (like Busycon carica) are found on the American side of the Atlantic and may grow up to 30–35 cm.

Periwinkles or sea snails (Littorina littorea) Nearly 300 species are known throughout the world, but few reach edible size. Periwinkles are found among seaweed on the rocky shores of the eastern coast of North America from Canada to lDelaware. Usually dark brown in color, the shell is rounded with concentric ridges and dark lines. Periwinkles are a common food in Europe but are not harvested in large numbers.

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Species of Meat Animals | Shellfish

Cephalopods Cephalopods are molluscs closely related to snails and include squid, nautilus, cuttlefish, and octopus. Cephalopods are found in most of the world's oceans in plentiful supply.

Squid (Loligo pealei, Illex illecegrosus, and Loligo opalescens) Squid, commonly called calamari, are found in the northwest Atlantic Ocean and on the Pacific coast. There are marine cephalopods with two long tentacles and eight shorter arms, a long tapered body, two triangular fins, and an internal shell (Figure 7). Squid sizes range from 7.5 cm to as large as 17 m for the giant squid. Squid landings for edible food have greatly increased over the past 25 years; most are from Pacific harvest and more than half are exported to Asian markets, especially Japan. Loligo vulgaris, found throughout Europe, weigh up to 2 kg and are noted to propel themselves out of the water, like a missile.

Octopus (Octopus spp.) Unlike the cuttlefish and squid, the octopus has no internal shell. There are several species of edible octopus. The giant octopus ranges the coastal waters off northern California through the Gulf of Alaska and around the Pacific Rim to Japan and Korea. Typically they are found in waters shallower than 180 m. The octopus has a large head, a soft oval body, well-developed eyes, and eight arms containing rows of suckers (Figure 8). Edible species range in size from 1 to 3 m in length. Octopus is available live, fresh, frozen, and cooked.

Figure 7 Squid. © Avril Bourquin.

Spiced and boiled octopuses are prepared with the viscera and eyes removed. Pickled octopuses are primarily available in Mediterranean and Asian fish markets.

Cuttlefish (Sepia spp.) Cuttlefish are caught for food in the Mediterranean, East Asia, the English Channel, and elsewhere. Squid is more popular as a restaurant dish all over the world. Cuttlefish ink was formerly an important dye, called sepia.

Welfare Issues Animal welfare has become increasingly important worldwide. A fundamental issue when deciding on our moral duties toward animals is whether they are capable of experiencing pain and other forms of suffering. The welfare of shellfish has been much less studied than that of mammals, birds, and even finfish. A summary of findings relevant to the welfare of cephalopods and decapods follows. There is evidence that cephalopods have a nervous system and relatively complex brain similar to many vertebrates, with good learning ability, and memory retention. They release adrenal hormones in response to situations that would elicit pain and distress in humans, can learn to avoid painful stimuli and have nociceptors in their skin. Research has found the presence of opioids and opioid receptors in crabs. Also, in an avoidance learning experiment, crabs showed memory of aversive stimuli and learned to avoid them. In another experiment, noxious stimuli (irritating chemical solutions and physical pinching) applied to antennae caused prawns to display immediate reflex tail-flicking responses and also two prolonged activities, grooming of the antenna, and rubbing of the antenna against the side of their enclosure. These responses were blocked with the application of a local anesthetic. According to some authors, the previous findings suggest that at least some groups of shellfish (in particular, cephalopods and decapods) are capable of experiencing pain and suffering. This would have obvious implications for the industry, as some of the methods used to catch and kill these animals would then be questionable on ethical grounds. Others, however, think that one does not know enough yet to decide whether shellfish are sentient, i.e., capable of experiencing emotions such as pain. Even in this case, however, whether they should be given the benefit of doubt is still an open question so one should aim for procedures that ensure humaneness.

See also: Meat, Animal, Poultry and Fish Production and Management: Disease Control and Specific Pathogen Free Pig Production

Further Reading

Figure 8 Octopus. © Avril Bourquin.

Britannica (2003). Deluxe edition CD-ROM. Shellfish. In: Kennedy, V.S., Newell, R.I., and Eble, A.F. (Eds.), The Eastern Oyster: Crassostrea virginica. College Park, MD: The University of Maryland Press.

Species of Meat Animals | Shellfish EFSA, 2005. Scientific Opinion of the Panel on Animal Health and Welfare on a request from European Commission on Aspects of the biology and welfare of animals used for experimental and other scientific purposes. The EFSA Journal 292, 1–136. Elwood, R.W., Barr, S., Patterson, L., 2009. Pain and stress in Crustaceans? Applied Animal Behaviour Science 118, 128–136. Martin, R.E., Carter, E.P., Flick, G.J., Davis, L.M., 2000. Marine and Freshwater Products Handbook. Boca Raton, FL: Technomic. Mather, J.A., 2007. Cephalopod consciousness: Behavioural evidence. Diseases of Aquatic Organisms 17, 37–48. Negedly, R., 1990. Elsevier's Dictionary of Fishery, Processing, Fish and Shellfish Names of the World. Amsterdam: Elsevier. Oberrecht, K., 1997. Fish and Shellfish, Care and Cookery. New York: Stoeger Publishing. Peterson, J., 1996. Fish and Shellfish. New York: William Morrow.

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US Department of Commerce ,2002. Fisheries of the United States, 2001. Silver Springs, MD: National Marine Fisheries Service, Office of Science and Technology, Fisheries Statistics and Economics Division. Whiteman, K., 2001. The World Encyclopedia of Fish and Shellfish. Singapore: Anniss Publishing Limited.

Relevant Website http://en.wikipedia.org/wiki/ Separately for Oysters, Mussels, Lobsters, Spiny lobsters crayfish, Crab, Shrimp prawn, Krill, Squid, Cuttlefish, Octopus.

SPOILAGE, FACTORS AFFECTING

Contents Microbiological Oxidative and Enzymatic

Microbiological CO Gill, Agriculture and Agri-Food Canada, Lacombe, AB, Canada r 2014 Elsevier Ltd. All rights reserved. This article is a revision of the previous edition article by CO Gill, volume 3, pp 1324–1330, © 2004, Elsevier Ltd.

Glossary Catabolite repression The quick adaptation of bacteria to a preferred carbon and energy source through inhibition of synthesis of enzymes involved in catabolism of carbon sources other than the preferred one. Gram-negative bacteria Bacteria that are decolorized when stained with crystal violet dye after treatment with ethanol according to Gram's procedure. Gram-positive bacteria Bacteria that retain the crystal violet dye on treatment with ethanol according to Gram's procedure.

Introduction Meats are spoiled by microorganisms when microbes on or in the product cause changes to meat qualities that consumers perceive as being undesirable or frankly offensive. Undesirable or offensive changes can involve the appearance, odor, and/or flavor of the meat. Visible changes include the appearance of visible colonies or a layer of slime on the product surface; or changes in the color of meat, from red to brown, gray, or green. Changes in the odor of meat can range from strong, putrid, or sulfurous odors to mild, stale, aromatic, or acid odors. Flavor changes can be similarly variable, but during the development of microbial spoilage flavor changes can often be detected before spoilage odors are apparent. The spoilage conditions that develop will depend on the types of organisms that are present in the spoilage microflora. The composition of the spoilage flora will be affected by intrinsic properties of the meat, such as the pH and the water activity (aw) of the product; and by extrinsic factors, such as the atmosphere around the product and the temperature at which it is held. In addition, the form of spoilage that is manifest can be affected by the amounts of specific nutrients for some elements of the microflora that are present in the product. As meats are not necessarily homogeneous products,

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Partial pressure The pressure due to an individual gas in a mixture of gases. Spoilage flora (plural flora) A group of microorganisms that grow on food with ultimately deleterious effects. Water activity (aw) The ratio of vapor pressure of water in a food or substance to that of pure water at the same temperature. Wiltshire bacon The pork cured by immersion in brine.

spoilage need not be uniform over all parts of an item of meat. For example, spoilage of moist fat tissue of a meat cut may precede spoilage of the muscle tissue. Moreover, the environment around an item of meat need not be homogenous. For example, meat in clipped chub packs may be exposed to an aerobic environment in the regions of the clips but be anaerobic elsewhere. However, spoilage of one part of an item will usually render the whole item unacceptable.

Aerobic Spoilage of Raw Muscle Tissue Muscle tissue in the carcass immediately after slaughter is essentially sterile. The tissue is contaminated with bacteria from the hide and from the packing plant equipment and environment during the dressing and breaking of carcasses. Consequently, meat surfaces are contaminated with a variety of organisms that include psychrotrophs from environmental sources, which can grow at chiller temperatures, as well as mesophiles derived from flora associated with animals, which cannot grow on chilled meat. Initial numbers of bacteria on the surfaces of meat can exceed 104 cfu cm−2. However, improvement of processing hygiene at packing plants in recent

Encyclopedia of Meat Sciences, Volume 3

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Spoilage, Factors Affecting | Microbiological years has resulted in some plants at least routinely producing carcasses and cuts with initial numbers ofo102 cfu cm−2. Postrigor muscle tissue provides a rich medium for the support of bacterial growth. Although the major potential nutrient for bacteria is protein, most bacteria do not elaborate enzymes to attack complex compounds when simple compounds are readily available to support their growth. As lactic acid, amino acids, and glucose are readily utilized by most bacteria, and are generally abundant in muscle tissue, such simple substances, not proteins, are the initial nutrients for the spoilage flora (Table 1). The accumulation of lactic acid in the muscle tissue during the development of rigor can reduce the tissue pH to 5.5 or a little lower. The aerobic growth of many bacteria is not affected by such pH values, and the concentrations of solutes do not reduce the water activity to values that inhibit bacteria growth. Thus, aerobic growth of many bacteria on muscle tissue is initially constrained by temperature alone. In these circumstances, the organisms that can grow most rapidly at the prevailing temperatures will tend to overgrow competitors, to predominate in the spoilage flora. The extent to which the fastest-growing species dominate the flora will depend not only on the extent to which their rates of growth exceed those of competitors, but also on the absolute numbers of the initial flora and the initial fraction of the potentially dominant organisms. If the initial numbers of the flora are low, then the relatively large number of generations required before maximum numbers are attained will allow extensive expression of a growth rate advantage. However, if the initial numbers are high, but the numbers of the faster-growing organisms are relatively low, then the final flora may contain relatively large fractions of slower-growing organisms. Under aerobic conditions, the organisms that grow best on muscle tissue at chiller temperatures are Gram-negative, strictly aerobic pseudomonads and moraxellaceae (Table 2). The latter group includes acinetobacteria, moraxellae, and psychrobacteria. Although organisms of the latter groups are usually found in aerobic spoilage flora, they generally do not produce offensive metabolic by-products; pseudomonads, which do produce offensive by-products, are generally major components of the flora at spoilage onset, and often predominant. Consequently, aerobic spoilage at chiller temperatures is largely the result of the activities of pseudomonads.

Table 1 Typical concentrations of low-molecular weight soluble components of beef muscle tissue of normal pH from pasture-fed animals Substance

Concentration (mg g−1)

Lactic acid Creatine Amino acids Dipeptides Inosine monophosphate Nucleotides Glycogen Glucose 6-phosphate Glucose

9.0 5.5 3.5 3.0 3.0 1.0 1.0 0.2 0.1

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The pseudomonads are nutritionally versatile but generally exhibit strong catabolite repression during the utilization of substrates from complex media. Catabolite repression ensures that while a preferred substrate is available, metabolic pathways for the utilization of other substrates are suppressed. For pseudomonads, glucose and related substances are the preferred substrates. When these are metabolized, no by-products that impart objectionable odors or flavors to meat are produced. However, when such substrates are exhausted amino acids are utilized, with the production of ammonia and other by-products, such as organic sulfides, esters, and acids, which impart strong, putrid odors and flavors to meat. The amounts of glucose present in muscle tissues are limited. When glucose diffusing from within a piece of muscle can no longer meet the demand of bacteria proliferating at the surface, then pseudomonads in the flora will attack amino acids. When glucose is at concentrations in the tissue of approximately 0.1 mg g−1, as is typical for beef from pasture-fed animals, this will occur when the aerobic flora numbers approach 108 cm−2. With meat from feed-lotted cattle, glucose concentrations may exceed 1 mg g−1 and overt spoilage may not occur until numbers are 4108 cm−2. At these high numbers, offensive by-products are rapidly generated in organoleptically detectable quantities from amino acids. Thus, in these circumstances the onset of spoilage is abrupt, with the tissue being wholly unspoiled when glucose is available at the surface even though bacterial numbers are high. The abundance of nutrients other than glucose precludes growth of the aerobic spoilage flora being limited by the availability of nutrients. Instead, numbers increase to exceed 109 cm−2. At these numbers, putrid spoilage is visibly augmented by a layer of slime on the tissue surface. Growth of the aerobic flora is then limited by the rate at which oxygen can diffuse from the atmosphere into the slime layer. As catabolic activities decline because of the increasingly limited availability of oxygen, catabolite repression is relieved, and exoenzymes that degrade proteins and other complex substrates are synthesized. Such enzymes degrade structural elements of muscle tissue, which allows bacteria to move from the surface into the deeper tissues, between muscle fibers. If muscle tissue is deficient in glycogen at the time an animal is slaughtered, then the amount of lactic acid formed will be lower than usual, the pH of the tissue will remain high, and little or no glucose will be present in the postrigor muscle. The high pH does not affect the composition of the spoilage

Table 2 Rates of growth of Gram-negative bacteria from aerobic spoilage flora on muscle tissues of normal and high pH stored in air at 2 °C Organisms

Pseudomonas spp. Moraxella spp. Acinetobacter spp. Flavobacterium spp. Enterobacteriaceae Aeromonas spp.

Growth rate (generations/day) pH 5.6

pH 6.4

2.03 1.85 1.58 1.18 1.13 0.96

2.11 1.82 1.55 1.14 1.20 1.36

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Spoilage, Factors Affecting | Microbiological

flora. However, in the near or total absence of glucose, the pseudomonads will degrade amino acids at an early stage of spoilage flora development. At first, the amounts of offensive by-products produced by the relatively few bacteria are undetectable organoleptically. However, as the flora increases, offensive by-products accumulate until putrid spoilage is apparent when numbers are approximately 106 cm−2. Therefore, the deficiency of glucose in muscle tissue of high pH results in the meat being prone to early spoilage. Psychotrophic pseudomonads usually dominate aerobic spoilage flora when meat is held at temperatures ≤20 °C. At higher temperatures, mesophilic enterobacteria will predominate on moist meat surfaces. However, the enterobacteria also utilize glucose preferentially, and thus the course of spoilage with these organisms is similar to that resulting from the activities of pseudomonads.

Aerobic Spoilage of Fat and Organ Tissues and Minced Meats As moisture that evaporates from fat tissue surfaces cannot be replenished from within the tissue, fat tissue surfaces can dry and hence preclude the growth of bacteria. However, if fat tissues remain moist because the meat is held in a humid environment, then an aerobic flora will develop on the fat as on muscle tissue. Fat tissue surfaces are contaminated with exudate, from cut blood vessels and/or muscle tissues, that contains bacterial nutrients. However, the concentrations of bacterial nutrients on fat surfaces are generally low and the nutrients cannot be replenished from the underlying tissues. Thus, glucose is rapidly exhausted, and growth continues with the utilization of amino acids, and then lactic acid when preferred amino acids are depleted. Consequently, putrid spoilage becomes evident when numbers approach 106 cm−2, as with high-pH meat. However, the total amount of nutrients available may be inadequate for the flora to grow to numbers at which a visible slime layer is formed. That is, growth may be nutrient-limited rather than oxygen-limited. Organ tissues are generally of pH46 but can contain substantial concentrations of glucose. For example, liver can contain glucose at concentrations up to several milligrams per gram. Unlike muscle tissue, the tissue structures of liver and other organs allow bacteria from the surface to invade the deep tissues. However, the deep tissues are anaerobic, and thus growth of bacteria within the tissues is slower, and the bacteria growing these do not include the strictly aerobic organisms that predominate in the flora on the surface. Spoilage at surfaces exposed to air will then precede spoilage of deep tissues. Aerobic spoilage will proceed as with muscle tissue, but the formation of visible colonies or slime may precede or be contemporaneous with the development of spoilage odors when glucose concentrations are high. In addition, the tissues may be acidified, because when glucose is abundant it is converted extracellularly by pseudomonads to gluconic and 2oxogluconic acids. For minced meat products that are not preserved by high concentrations of solutes or acidification, spoilage at surfaces exposed to air will also precede deep spoilage, and proceed as for muscle tissue. Again, colony or slime formation may be

among the first symptoms of spoilage, if carbohydrates preferentially utilized by pseudomonads have been added to a product.

Anaerobic Spoilage The pigments in muscle and organ tissues – myoglobin and hemoglobin – react readily with oxygen at all partial pressures. Thus, when meats are sealed, with little or no headspace, in packs composed of materials that are nearly or wholly impermeable to oxygen, the residual oxygen will be removed from the meat environment quite rapidly. With raw tissues packaged in an essentially gas-impermeable material, such as laminated plastic films that include two layers of metalized film, anaerobic conditions will develop and be maintained. However, vacuum packages for meats are usually composed of plastic films with various low, but measurable, oxygen transmission rates at temperatures above 0 °C. In addition, some raw tissues, such as fat, and some meat products have only limited oxygenscavenging capabilities. Thus, in many circumstances, the environment at the surface of vacuum-packed product can be microaerobic rather than anaerobic. In either environment, growth of the strictly aerobic organisms that predominate in aerobic spoilage flora will usually be suppressed. Instead, spoilage flora dominated by anaerobic or facultatively anaerobic organisms develop. Unlike with aerobic spoilage, the types of organisms that contribute to the spoilage flora are determined by the pH of the meat as well as the storage temperature. Many spoilage organisms are unable to grow under anaerobic conditions on muscle tissue of normal pH (5.5) held at chiller temperatures. Under these conditions, the flora that develops is composed of Gram-positive lactic acid bacteria such as lactobacilli, carnobacteria, and leuconostocs, with organisms of the last group tending to predominate. The lactic acid bacteria are metabolically anaerobic, although they are aerotolerant. The substrates they can ferment to support growth on muscle tissue are limited to glucose and some other carbohydrates available in lower amounts. Thus, growth of the lactic flora ceases when the concentration of glucose at the tissue surface is depleted. This substrate limitation of the flora growth typically occurs when numbers are approximately 108 cm−2. When fermenting glucose, the lactic acid bacteria do not produce offensive by-products. Although most lactic acid bacteria cannot utilize amino acids to support growth, some amino acids, notably valine and leucine, may be metabolized with the production of volatile fatty acids as byproducts. The slow accumulation of such substances can impart acid/dairy flavors and, ultimately, odors to meat. Such flavors and odors are unusual for meat rather than grossly offensive, but they finally render the meat unacceptable to consumers some time after the flora has reached maximum numbers. Some strains of lactic acid bacteria can metabolize sulfur-containing amino acids, with slow production of hydrogen sulfide. Hydrogen sulfide can react with muscle or blood pigments to spoil the meat by green discoloration. Hydrogen peroxide produced by some lactic acid bacteria under microaerobic conditions can also cause the green discoloration of fresh and cured meats. If the pH of the meat is above 5.8, facultative anaerobes of high spoilage potential can grow on products held under

Spoilage, Factors Affecting | Microbiological anaerobic conditions at chiller temperatures. Such organisms include psychrotophic enterobacteria, Shewanella putrefaciens, and Brochothrix thermosphacta. Under anaerobic conditions, the enterobacteria will ferment glucose while it is available, and then utilize amino acids when glucose is exhausted. Some amino acids are decarboxylated to give malodorous amines, while hydrogen sulfide as well as organic sulfides may be produced from others. All such by-products grossly affect the odor and flavor of meat, and hydrogen sulfide can cause green discoloration. Shewanella putrefaciens can form part of an aerobic spoilage flora, in which its behavior is similar to that of the pseudomonads. However, unlike the pseudomonads, it utilizes the amino acids serine and cysteine even when glucose is available. Hydrogen sulfide and organic sulfides derived from the latter substrate contribute to spoilage odors and flavors. The organism is not fermentative, but under anaerobic conditions it can utilize a variety of terminal electron acceptors other than oxygen to maintain respiratory metabolism. Under anaerobic conditions, hydrogen sulfide is produced in abundance, with consequent degradation of the color, odor, and flavor of product. Brochothrix thermosphacta ferments glucose to lactic acid, and therefore under strictly anaerobic conditions its spoilage potential is limited. Under aerobic conditions, glucose is metabolized to acetoin, diacetyl, and a variety of fatty acids and alcohols. These products of aerobic metabolism impart strong, stale, and sour odors and flavors to meat. Thus, under conditions where some aerobic metabolism is maintained, these by-products can spoil meat. Unlike pseudomonads, enterobacteria, and lactic acid bacteria, which produce offensive by-products only when preferred carbohydrate substrates are unavailable, B. thermosphacta and S. putreficiens can produce offensive by-products at all times during their growth on meat. Therefore, even when the numbers of these organisms are less than 106 cm−2, offensive by-products may be produced in detectable quantities to spoil the meat, irrespective of the state of growth of the spoilage flora as a whole. However, the maximum numbers of the potent spoilage organisms in an anaerobic flora are usually constrained by the lactic acid bacteria, which sequester nutrients and produce inhibitory bacteriocins. The inhibition of other organisms by lactic acid bacteria occurs only as the flora approaches its maximum numbers. Before that, the various types of bacteria grow at rates that are determined by the temperature and the environment provided by the meat, without any obvious interactions between types of bacteria. Thus, whether or not the potent spoilage organisms contribute to the spoilage of anaerobically stored meat, when pH does not inhibit their growth, will depend on their numbers in the initial flora. If their numbers are low relative to the numbers of lactic acid bacteria, growth of the potent spoilage organisms can be suppressed before they reach numbers sufficient to elaborate offensive by-products in detectable quantities; but if their numbers are relatively high, they will reach numbers sufficient to cause spoilage before growth ceases. Although lactic acid bacteria, particularly leuconostocs, have a growth rate advantage at chiller temperatures, that advantage reduces at increasing temperatures (Table 3). At abusive temperatures, enterobacteria and B. thermosphacta can

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Table 3 Rates of anaerobic growth of bacteria from anaerobic spoilage flora at abusive and warm temperatures Organism(s)

Leuconostoc spp. Enterobacter spp. Brochrothrix thermosphacta Escherichia coli

Growth rate (generations/day) 10 °C

20 °C

30 °C

3.9 2.8 2.5 1.9

10.4 10.9 14.1 11.4

15.0 12.6 15.7 17.1

compete effectively with the lactic acid bacteria; and at warm temperatures, anaerobic flora can be dominated by enterobacteria. In addition to the usual microbial spoilage conditions of vacuum-packed meats, both raw and cooked meats may be spoiled by psychrotrophic clostridia. A number of species can apparently be involved in such spoilage, which often involves some swelling (blowing) of packs. However, gross swelling of vacuum-packed chilled meats stored for short times at non-abusive temperatures appears to be due largely to the fermentation of lactic acid by Clostridium estertheticum. Other clostridia can cause softening of meat, with the release of large volumes of exudate and the development of putrid and sulfurous odors. The organisms responsible for the production of the large volumes of gas and the proteolytic degradation of the muscle tissue are often difficult to recover. Usual methods for enumerating and isolating bacteria from meat generally recover a flora of mainly lactic acid bacteria from meat spoiled by psychrotrophic clostridia. In view of the difficulties with their recovery and the limited understanding of the circumstances under which they appear in meat spoilage flora, it is possible that psychrotrophic clostridia are involved in meat spoilage more often than is now recognized. Studies aimed at characterizing meat spoilage flora by molecular methods, and identifying the metabolic activities of psychrotolerant clostridia growing on meat, may resolve the current uncertainties about their roles in meat spoilage.

Spoilage in Modified and Controlled-Atmosphere Packagings Modified-atmosphere packagings are filled with aerobic atmospheres that are usually rich in oxygen, and which have concentrations of carbon dioxide (CO2) sufficient to inhibit growth of pseudomonads. As large volumes of CO2 can dissolve in meat, and CO2 and oxygen can exchange across packaging films, the atmosphere can change during storage. Controlledatmosphere packagings are those in which a stable atmosphere is maintained throughout storage of the product. The only packagings of this type used with meats employ pouches made of gas-impermeable films that are filled with an atmosphere of CO2 to obtain an anaerobic atmosphere. The growth rates of pseudomonads decrease with increasing CO2 concentrations up to approximately 20%. Increases in CO2 concentrations beyond that do not greatly reduce the rate of growth provided the atmosphere is aerobic. The maximum reduction in the rate of growth of pseudomonads is

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Spoilage, Factors Affecting | Microbiological Table 4

Examples of conditions tolerated by spoilage organisms growing on meats

Organisms

Gram-negative bacteria Gram-positive bacteria Yeasts Molds

Conditions Minimum aw

Minimum pH

Maximum salt concentration (%)

Maximum sorbate concentration (ppm)

0.95 0.90 0.80 0.75

4.4 3.8 2.0 1.7

10 15 20 o20

100 700 400 1000

approximately 50%. A reduction of that order is sufficient to allow lactic acid bacteria, which are not affected by CO2 at such concentrations, to outgrow pseudomonads and dominate the spoilage flora. However, B. thermosphacta and enterobacteria are also unaffected by the CO2, and thus can form large fractions of the spoilage flora. In such circumstances, B. thermosphacta can cause early spoilage of a product as the flora develops. Enterobacteria cause spoilage as glucose is exhausted by the activities of the total flora. As a controlled atmosphere of carbon dioxide is anaerobic, growth of pseudomonads is totally inhibited. Such an atmosphere also inhibits the growth of enterobacteria, raises the minimum temperature for growth of B. thermosphacta, and probably affects some elements of the lactic flora. Consequently, meat in a carbon dioxide atmosphere generally supports a lactic flora and develops acid/dairy flavors only well after the flora attains maximum numbers.

Bacterial Spoilage of Preserved Meats Meats are preserved by drying; by the addition of salt or other solutes in quantities sufficient to reduce the water activity to levels at which growth of spoilage bacteria is affected; by fermentation of added carbohydrates or addition of acidulants, to reduce the pH; or/and by addition of antimicrobial agents, such as curing salts (nitrate/nitrite), sulfite, and benzoate. The Gramnegative organisms that spoil products rapidly are mostly susceptible to relatively mild preservative treatments (Table 4). Inclusion of preferentially utilized carbohydrates in preserved meats also tends to inhibit the production of ill-tasting and malodorous byproducts. Bacterial flora of preserved meats is then commonly dominated by Gram-positive organisms of low spoilage potential, with microbial spoilage being first manifest as slime or visible colonies, or discoloration of cured products. However, certain preserved meats tend to develop a flora enriched for specific spoilage organisms and thus undergo spoilage in a product-typical fashion. Examples of such products are raw sausages preserved with sulfite, which are usually spoiled by B. thermosphacta, as that organism is tolerant of the preservative, and Wiltshire bacons, which can be spoiled by the activities of salt-requiring vibrios.

Spoilage by Yeast and Molds Yeast and molds grow far more slowly than the spoilage bacteria and thus will cause meat spoilage only when conditions

Table 5 Growth rates of bacteria, yeasts, and molds at 0 °C and subzero temperatures Type of Name of organism(s) organism(s)

Growth rate (per day)a 0 °C

−2 °C

−5 °C

Bacteria

1.75 0.48 1.03 0.60 0.67 0.31 0.35 0.19

1.00 0.19 0.57 0.43 0.50 0.18 0.17 –

– – 0.11 0.09 0.03 0.03 – –

Yeasts Molds

Pseudomonas spp. Leuconostoc spp. Cryptococcus infirmo-miniatus Cryptococcus laurentii Thamniduim elegans Cladosporium herbarum Penicillium hirsutum Penicillium corylophilum

a

Growth rates of bacteria and yeasts are generations/day. Growth rates of molds are increase in length per unit length per day of hyphae from newly germinated spores.

prevent bacterial growth. Most yeasts and molds can grow only aerobically and are inhibited by relatively low concentrations of carbon dioxide, and therefore atmospheres other than air do not favor their growth. However, yeasts and molds can commonly tolerate lower water activities and more acidic conditions than spoilage bacteria, and some can grow at lower temperatures or are less affected by preservatives than the bacteria. Yeasts generally grow more rapidly than molds, and hence when conditions allow the growth of both, but prevent the growth of bacteria, spoilage will likely be caused by yeasts. Spoilage by molds or yeasts is usually due to the development of visible colonies on product surfaces. On raw meats, mold spoilage occurs when desiccation of the surface prevents the growth of spoilage bacteria. The surfaces of chilled carcasses can become desiccated and develop mold colonies when circulating air of low humidity prevents the dry surfaces of muscle tissues being rehydrated by the water that moves from within the muscle. Fat surfaces will obviously remain dry under such conditions and may also support mold growth. Mold spoilage also occurs on frozen raw meats that experience prolonged periods of temperature abuse. The minimum temperature for growth of spoilage bacteria is approximately −3 °C, whereas that for molds and yeast is approximately −5 °C. It has therefore been assumed that temperature alone can dictate mold instead of bacterial spoilage. In fact, molds grow very slowly at −5 °C compared with yeasts (Table 5), so when only temperature and the depression of water activity associated with freezing affect microbial growth, visible yeast colonies can be formed long before mold colonies appear. Mold colonies are the main

Spoilage, Factors Affecting | Microbiological manifestation of spoilage when substrate limitation precludes the formation of yeast colonies, or when surfaces desiccate to give water activities below those tolerated by yeasts. Such desiccation can occur by sublimation of ice from frozen tissues, but in practice the appropriate conditions for mold spoilage of frozen meat seem to arise when surfaces thaw, perhaps cyclically, and water evaporates into the dry, refrigerated air. Yeasts and mold colonies can also cause spoilage of cured and preserved meats of low water activity, whereas raw meats preserved by the addition of sulfite can be spoiled by fermentative yeasts.

See also: Bacon Production: Bacon; Wiltshire Sides. Chemical and Physical Characteristics of Meat: Adipose Tissue; Chemical Composition; pH Measurement. Curing: Brine Curing of Meat; Dry. Meat Marketing: Cold Chain. Microbiological Safety of Meat: Hurdle Technology. Packaging: Equipment; Modified and Controlled Atmosphere; Overwrapping; Vacuum. Refrigeration and Freezing Technology: Applications; Principles; Thawing. Sausages, Types of: Cooked; Dry and Semidry; Fresh

Further Reading Corry, J.E.L., 2007. Spoilage organisms of red meat and poultry. In: Mead, G.C. (Ed.), Microbiological Analysis of Red Meat, Poultry and Eggs. Cambridge, UK: Woodhead Publishing, pp. 101–122. Davies, A., Board, R., 1998. The Microbiology of Meat and Poultry. London: Blackie Academic.

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Gill, A.O., Gill, C.O., 2010. Preservative packagings for fresh meats, poultry and fin fish. In: Han, J.H. (Ed.), Innovations in Food Packaging. Amsterdam: Elsevier, pp. 204–226. Gill, C.O., 1988. Microbiology of edible meat by products. In: Pearson, A.M., Dutson, T.R. (Eds.), Edible Meat By-Products. London: Elsevier, pp. 47–82. Nychas, G.J.E., Douglas, L.M., Sofos, J.N., 2007. Meat, poultry and seafood. In: Doyle, M.P., Beuchat, L.R. (Eds.), Food Microbiology. Fundamentals and Frontiers. Washington, DC: ASM Press, pp. 105–140. Pennacchia, C., Ercolini, D., Villani, F., 2011. Spoilage-related microbiota associated with chilled beef stored in air or vacuum pack. Food Microbiology 28, 84–93. Samelis, J., Kakouri, A., Rementzis, J., 2000. Selective effect of the product type and the packaging conditions on the species of lactic acid bacteria dominating the spoilage microbial association of cooked meats at 4 °C. Food Microbiology 17, 329–340. Yang, X., Balamurugan, S., Gill, C.O., 2011. Effects on the development of blown pack spoilage of the initial numbers of Clostridium estertheticum spores and Leuconostoc mesenteroides on vacuum packed beef. Meat Science 88, 361–367.

Relevant Websites http://www.meatupdate.csiro.au/data/Chilled_meat_for_export_02-91.pdf Commonwealth Scientific and Industrial Research Organization (CSIRO), Australia. http://www.ime13.org/programs/presentations/mhardin%20presentation-mprc.pdf IEH Laboratories. http://www.redmeatinnovation.com.au/innovation-areas/food-safety/food-safetypublications Meat and Livestock Australia. http://www.beefresearch.org/CMDocs/BeefResearch/Beef%20shelf-life.pdf National Cattlemen's Beef Association. http://www.scientificamerican.com/article.cfm?id=how-do-salt-and-sugar-pre Scientific American.

Oxidative and Enzymatic J Aalhus and M Dugan, Agriculture & Agri-Food Canada, Lacombe Research Centre, Lacombe, AB, Canada Crown Copyright r 2014. Published by Elsevier Ltd. All rights reserved. This article is a revision of the previous edition article by JL Aalhus, MER Dugan, volume 1, pp 1330–1336, © 2004, Elsevier Ltd.

Glossary Anserine An imidazole dipeptide of the amino acids β-alanine and N-methylhistidine, found in skeletal muscle, which acts as an antioxidant due to its chemical structure. Carnosine An imidazole dipeptide of the amino acids β-alanine and L-histidine, found in skeletal muscle, which acts as an antioxidant due to its chemical structure. Ferrylmyoglobin Metmyoglobin (Fe3+) activated with hydrogen peroxide to yield a relatively stable hypervalent (Fe4+) heme protein (without a protein-based radical) with prooxidant activity. Free radical An atom or group of atoms that has at least one unpaired electron and is therefore unstable and highly reactive. Glutathione peroxidise An enzyme family found in muscle, whose preferred substrate is hydrogen peroxide and main biological role is to protect the organism from oxidative damage. Malondialdehyde A compound produced by oxidation of unsaturated fatty acids. Metmyoglobin A brown-colored pigment found in meat, formed from myoglobin by oxidation of iron from the ferrous (Fe2+) to the ferric (Fe3+) state. Myoglobin An iron-containing protein (pigment) found in meat, consisting of heme (iron) connected to a single

Introduction Spoilage of meat occurs when there is deterioration of its odor, flavor, color, texture, and/or nutritive properties. These changes may result from chemical, physical, enzymatic, or microbiological processes. Oxidation, or the process of loss of electrons, hydrogen abstraction, or flow of unpaired electrons, may occur in all the chemical constituents of muscle foods. Peroxidation of lipids will become apparent to consumers by the development of rancid odors or flavors, and ‘warmed-over’ flavor (WOF) in previously cooked meats. Oxidation of meat pigments is recognizable by the development of brown discoloration replacing the normally acceptable bright red meat color. Oxidation of meat proteins leads to the loss of functional properties such as gel-forming ability, meat-binding ability, emulsification capacity, solubility, viscosity, waterholding capacity, and nutritive value. Changes to functional properties may result in a loss of texture in further processed meats or, in some cases, an increase in toughness/hardness and decrease in juiciness in whole muscle foods. Because of these deleterious changes associated with oxidation, much of the applied research in the meat industry is directed toward slowing the rate of oxidative reactions. Endogenous catalysts,

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peptide chain. Myoglobin’s role in muscle is to transport oxygen released by red blood cells to the mitochondria, where the oxygen is used to produce energy. Oxymyoglobin The form of myoglobin that is complexed with an oxygen molecule – the color of meat most acceptable to consumers. Perferrylmyoglobin Metmyoglobin (Fe3+) activated with hydrogen peroxide to yield a transient hypervalent (Fe4+) heme protein (with a protein-based radical) with prooxidant activity. Reductase Any enzyme that catalyzes a biochemical reduction reaction. Superoxide dismutase An enzyme that catalyzes the conversion of superoxide into hydrogen peroxide and oxygen. Thiobarbituric acid (TBA) A widely used test for determining the extent of lipid oxidation by measuring the concentration of relatively polar secondary reaction products such as aldehydes. Warmed-over flavor (WOF) An unpleasant flavor (rancid, stale) arising from heme-mediated lipid oxidation that develops in cooked meat that is subsequently refrigerated before reheating.

antioxidants, and enzymes can all affect oxidation rates. In addition, oxidation rates can be affected by numerous interventions throughout the production chain, such as incorporation of antioxidants into animal feed, packaging systems, temperature control, exposure to light, or direct addition of antioxidants, metal chelators, dipeptides, etc. during processing. In the context of the present review, only enzymes that affect rates of lipid oxidation are considered. In addition, recent research on the oxidation of enzymes associated with changes in texture (proteolysis), which can contribute to decreased tenderization postmortem, will be overviewed. However, the mechanism of action of these enzyme systems and their postmortem activity, which may result in spoilage due to overtenderization, are discussed elsewhere.

Peroxidation of Lipids Lipid peroxidation is the major form of quality deterioration, including flavor, odor, taste, color, texture, and appearance, leading to spoilage in meat and fish products, even when lipid content is fairly low. In lean beef, triacyglycerols and phospholipids comprise 2–4% and 0.8–1% of the meat weight,

Encyclopedia of Meat Sciences, Volume 3

doi:10.1016/B978-0-12-384731-7.00091-X

Spoilage, Factors Affecting | Oxidative and Enzymatic respectively. Only oleic, palmitic, and stearic fatty acids are present in substantial amounts in the fat of meat animals, combined with glycerol to form the triacylglycerols. The phospholipids, the so-called ‘structural lipids,’ are located in the membranes and contain over 40% polyunsaturated fatty acids (PUFA; 22% 18:2n−6, linoleic acid; 2% 18:3n−3, linolenic acid; 15% 20:4n−6, arachidonic acid; 1% 20:5n−3, eicosapentaenoic acid (EPA); and 2% 22:6n−3, docosahexaenoic acid (DHA)). Owing to their high level of unsaturation and their proximity to the heme catalysts of the mitochondria and microsomes, the initial oxidation reactions in meat generally involve the phospholipids. Chicken and turkey muscle are more susceptible to oxidation than beef due both to the higher levels of polyunsaturated phospholipids and lower levels of antioxidants in the poultry meats. Fish muscle is even more susceptible to oxidation due to the high degree of unsaturation, including enrichment with the characteristic omega-3 fatty acids, EPA, and DHA. Recent applied research efforts to shift the fatty acid composition of meat animals (e.g., beef and pork) toward increased long chain omega-3 PUFA to improve human dietary health may result in increased rates of oxidation, particularly in high-fat muscles and meat products. In this context, Australia has recently recognized the potentially important contribution to human dietary health of the long chain omega-3 PUFA, docosapentaenoic acid (DPA), which is present in quite high levels in ruminant animals (e.g., beef and lamb). Refrigerated, whole, raw meat is relatively resistant to lipid peroxidation. Under the appropriate conditions, frozen beef has been found to maintain an acceptable quality for 10 years or more, provided desiccation (freezer burn) is avoided. However, oxidation of the tryacylglycerol fraction does proceed slowly and is referred to as ‘normal oxidation,’ as opposed to WOF, which is a rapid, heat-activated oxidation affecting mainly the phospholipids.

Normal Lipid Peroxidation In whole meat, fats are compartmentalized away from propagators of oxidation. However, prolonged storage under unfavorable conditions can create rancid odors described as tallowy for beef; muttony for mutton; stale, cheesy, acrylic, fishy, or oily for pork; and rancid, painty, fishy, and cod-liver oil-like for fish. These odors develop from the products of autoxidation of unsaturated fatty acids, such as oleic, linoleic, linolenic, and arachidonic. Three stages have been proposed to describe the autoxidation process, namely, initiation, propagation, and termination (Figure 1). Initiation occurs when an unsaturated fatty acid reacts with O2 to produce a free radical. The actual formation of the free radical occurs when a labile hydrogen is abstracted from the carbon atom adjacent to the double bond. The free radical then reacts with oxygen to form a peroxyl radical, which in turn can abstract another hydrogen from a different fatty acid, resulting in the propagation of a chain reaction. Termination occurs when two free radicals react together, when a peroxyl radical reacts with a free radical, when two peroxyl radicals react, or when radicals react with other meat constituents (e.g., vitamins, amino acids, dipeptides, etc.). The hydroperoxides formed during

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Polyunsaturated fatty acid (PUFA) Initiation through hydrogen abstraction (Catalysts: light, metal ions, peroxides, heat) Alkyl radical + H· O2 addition

Peroxy radical PUFA Propagation (Hydrogen abstraction from other PUFA)

Hydroperoxide Termination (Formation of nonradical products) Aldehydes, hydrocarbons etc. Figure 1 Fatty acid oxidation showing initiation, propagation, and termination steps.

propagation decompose and form secondary products that include aldehydes generated from the methyl ends of the fatty acids. Aldehydes, the types of which depend on the structure of the parent fatty acids, are largely responsible for rancid flavor development in meats. The degree of rancidity in fats has been traditionally measured using an assay for the determination of malondialdehyde by its reaction with thiobarbituric acid (TBA). However, the TBA assay is not specific to malondialdehyde and in some cases has been found to overestimate malondialdehyde content up to ninefold. Hence, assays specific to malondialdehyde or other specific aldehydes may be preferable for determining the development of rancidity in meats. Rancidity in refrigerated and frozen whole meat products can be prevented through appropriate handling and packaging. Although some inherent factors (Vitamin E levels and animal age) can be controlled through management practices, others can be implemented in the postmortem period. Packaging under atmospheres of low-oxygen partial pressure and vacuum packaging are useful means of prolonging the oxidative stability of meat products. Packaging under oxygen-free atmospheres of nitrogen or carbon dioxide is an even more effective means of increasing the stability of meat products. The use of opaque packagings reduces exposure to light and this can further reduce the rate of oxidation. Grinding of meat, as in hamburger manufacture, disrupts membrane integrity and exposes the lipids to metal catalysts, and thus accelerates oxidation. Appropriate temperature control will minimize oxidation. Fish is particularly susceptible to temperature abuse as lipid peroxidation can continue even in the frozen muscle. At −4 °C, rancidity in fish is accelerated because freezing of a large fraction of free water as pure ice causes concentration of the catalytic metals in the unfrozen fraction. Frozen storage of meat at steady temperatures (−18 °C or lower) in tight-fitting, moisture-proof packaging is required to minimize lipid

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peroxidation and prevent freezer burn. Unfortunately, consumers’ need to assess the appearance of fresh meat products leads to nonoptimum conditions for preserving oxidative stability during retail display and home storage.

Warmed-Over Flavor (WOF) WOF is one of the major causes of quality deterioration in cooked, refrigerated, and precooked meat products. WOF includes both the development of undesirable flavors and the loss of desirable meat flavor characteristics. The odors and flavors associated with WOF are commonly described as painty, rancid, stale, and cardboard-like. WOF can develop rapidly: in 48 h or less in reheated, refrigerated meat, and within a matter of days in precooked, frozen meats. WOF results from the oxidation of PUFA located mainly in the cell membrane as phospholipids. The highly reactive sites next to the double bonds readily lose hydrogen atoms, resulting in the formation of lipid free radicals. Free radicals rapidly react with oxygen, to yield aldehydes such as pentanal, pentenal, hexanal, hexenal, and 2,4-decadienal. These compounds are volatile and perceptible as WOF at low concentrations (ppb). Unsaturated aldehydes are perceptible at lower concentrations than saturated aldehydes. Hence, muscles that are high in PUFA content are also the most susceptible to WOF development. This translates into a species difference in WOF development, with the problem for meats in the order fish4poultry4pork4beef4lamb. With the addition of advanced analytical technologies (e.g., gas chromatography–mass spectrophotometry with an olfactory port (GC–MS-O) and the electronic nose), progress in identification of the compounds directly related to the sensory perception of WOF continues to be made for different species, muscles, and types of muscle foods. The rate of oxidation of PUFA can be influenced by catalysts that reduce the energy required for oxidation (metals, high-energy oxygen, or enzymes) or that add energy to drive the reaction (heat, light, oxidizing enzymes). During cooking, heat causes extensive protein coagulation and loss of functional properties. Of particular importance for lipid stability is the loss of iron-binding capacity in hemoglobin and myoglobin. On heating, free iron released from the globin proteins can come into contact with oxidizable substances such as PUFA. Free iron in the reduced, ferrous (Fe2+) state readily converts into its oxidized, ferric (Fe3+) state, assisting in the generation of lipid free radicals that then propagate a lipid peroxidation chain reaction. Hence, once heating occurs, oxidation proceeds very rapidly. Salt has been shown to enhance iron-catalyzed oxidation. Transition metals other than iron can also play a role in lipid peroxidation and are often added during processing through the addition of water and spices. Similar to iron, they undergo the loss of a single electron (e.g., Cu2+ to Cu3+) during oxidation, and catalyze the formation of free radicals from PUFA. Certain wavelengths of light (particularly blue-purple fluorescent and ultraviolet) are able to promote the oxidation reaction. Light energy elevates the energy states of oxygen and meat pigments, increasing their ability to participate in

oxidation. Hence, the quality of light used during retail display of meat products and precooked frozen items is of concern. Because oxygen is integral to the formation of WOF, any process that increases oxygen content in the muscle increases the problem. Mechanical manipulation through grinding, chopping, deboning, mixing, and tumbling introduces air into the normally anoxic interior of whole muscle cuts. Although a number of factors can trigger oxidation and add to the development of WOF, there are also a number of ways of preventing or delaying its development. In the raw product, it is important to use fresh materials that have had little time to undergo extensive enzymatic oxidation preventing the production of autocatalytic substances that can cause oxidation even after the enzymes themselves have been inactivated by heat. Antioxidants protect PUFA from oxidation by undergoing oxidation themselves, thus delaying the development of WOF. However, the protective effect of an antioxidant is dependent on its concentration and fat solubility, and on the number of antioxidative sites on the molecule. Dietary supplementation of the naturally occurring vitamin E (α-tocopherol) has been shown to reduce the susceptibility of meat to oxidation. α-Tocopherol is readily stored in the cell membrane, preventing the oxidation of nearby PUFA. Carotenoids are another group of fat-soluble antioxidants that can be obtained from the diet and can react with singlet oxygen to block the formation of lipid peroxides. However, their inclusion at high concentrations can lead to discoloration of fats, skeletal muscle, and associated skin. Although this can be detrimental in some muscle foods, carotenoids are purposefully added to both salmon and poultry diets to enhance the color of the final product. Various synthetic phenolic substances, including butylated hydroxyanisol (BHA), butylated hydroxytoluene (BHT), tertiary butylhydroxyquinone (TBHQ), and propyl gallate (PG), can be used as antioxidants in muscle food systems. In addition, some common herbs and spices such as rosemary, marjoram, sage, thyme, mace, allspice, and clove have antioxidant properties. In cured meats, nitrite is known to have a powerful antioxidative effect, although the mechanisms are not clearly understood. Mechanisms that may be involved include prevention of ferrous iron release via complex formation with heme pigments, stabilization of PUFA in cell membranes, and chelation of metal ions. The histidine-containing dipeptides found in muscle tissue, carnosine, and anserine have been found to have antioxidant activity in addition to their pH-buffering capacity. Species differences exist, with pigs, beef, and turkey having higher concentrations of carnosine than anserine, and the reverse being the case for salmon, rabbit, and chicken. Primarily anaerobic muscles have higher carnosine and anserine concentrations than aerobic muscles. The antioxidant mechanism of carnosine and anserine may be due to metal chelation or free radical scavenging. Many of the lipid peroxidation catalysts and free radicals are found in the cytosol, and hence the hydrophilic nature of carnosine and anserine is probably significant for their antioxidative activity. Chelating agents such as citric acid, ethylenediaminetetracetic acid (EDTA), sodium tripolyphosphate, pyrophosphate, or hexametaphosphate are effective in reducing

Spoilage, Factors Affecting | Oxidative and Enzymatic oxidation that is initiated or propagated by metal ions. These agents form stable complexes with metals, thereby preventing their involvement in the oxidation of PUFA. Oxygen scavengers such as ascorbic acid and erythorbic acid are added to cured meats to prevent nitrosamine formation, but also to prevent lipid oxidation. They act alone as reducing agents in low concentrations, and synergistically with other antioxidants. Ascorbic acid can form a stable complex with metals, thereby raising the energy required to initiate oxidation. Exclusion of oxygen through physical means such as vacuum tumbling, vacuum stuffing, and vacuum packaging can delay the onset of WOF. Oxygen can also be excluded by covering precooked products with liquids or sauces. Owing to the antioxidant nature of Maillard (browning) reaction products (particularly histidine-glucose reaction products), covering pork with drippings or gravy made from the drippings can also increase the acceptable frozen storage life in precooked products. The use of red-orange tungsten halogen lights for illumination may also be beneficial, and the complete exclusion of light may be a necessity for some products.

Oxidation of Pigments Muscle color is a major factor in consumer selection of meat on retail display and is, in some cases, mistakenly relied on as an indicator of freshness. Hence, consumers have firm expectations about fresh meat color, and deviations, particularly browning, are thought to indicate spoilage. The pigment primarily associated with meat color is myoglobin, which in the living animal functions in the transfer of oxygen from hemoglobin in the blood to the mitochondrial

cytochromes. Myoglobin constitutes 50–80% of the meat pigments, depending on the species, age of the animal, and muscle type. Higher concentrations of myoglobin are found in beef than in pork, in older than in younger animals, and in muscles responsible for sustained activity than in muscles that are used sporadically, and less intensively. Hence, in bright, cherry-red beef, the myoglobin concentration ranges from 4 to 10 mg g−1 (wet matter basis) compared to 1–3 mg g−1 for grayish-pink pork. In dark-colored beef the range is from 16 to 20 mg g−1 compared to light-colored veal at 1–3 mg g−1. The extensor carpi radialis, a locomotory muscle located in the forelimb, has twice the myoglobin concentration of the longissimus thoracis et lumborum, the major support muscle along the vertebrae (12 vs. 6 mg g−1, wet matter basis). These differences in intensity of color are familiar to and, for the most part, accepted by consumers. In the native deoxymyoglobin state (Mb), before exposure to oxygen, meat pigments are purplish-red (Figure 2). This can be seen when the interior of meat is first exposed during cutting or when fresh meats are vacuum packaged in oxygenimpermeable film. On exposure to atmospheric oxygen, the pigments are rapidly oxygenated, producing oxymyoglobin (MbO2) and the bright red, ‘bloomed’ color of fresh meat. Brown metmyoglobin (MMb) is formed by oxidation of the pigment from its ferrous (Fe2+) to its ferric (Fe3+) iron state under conditions of low-oxygen partial pressure. Hence, in intact meat, the depth of oxygen penetration into the interior of the meat is marked by a layer of brown MMb. In muscle, the three states of myoglobin exist simultaneously; in vivo MMb exists at a steady state of approximately 2–3%, whereas in meat color deterioration is not perceptible until greater than 30% of the pigments are in the oxidized

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MMb state. Fresh beef is considered to have an unacceptable color when over 60% of the myoglobin is in the MMb form. Discoloration discounts at retail have a significant economic impact, calculated to be in excess of US$700 million per year in the US beef industry alone. Though the conversion of MbO2 to MMb is thermodynamically favored, reduction of MMb to ferrous myoglobin may also occur. The MMb is reduced nonenzymatically by reduced cytochrome b5. In turn, cytochrome b5 is regenerated to its active reducing form by cytochrome b5 reductase (MMb reductase), which utilizes the reduced form of nicotinamide adenine dinucleotide (NADH). Once the reducing capacity of the meat is exhausted, complete MMb formation will occur. MMb reductase activity has been shown to differ among muscles, with, for example, the longissimus muscle having greater activity than the psoas major muscle. In addition to loss of MMb reductase activity, color stability is reduced by any factors that cause denaturation of the globin (e.g., heat, salts, low pH, and ultraviolet light) and by lowoxygen tension. The formation of MMb is maximal at an oxygen pressure of approximately 4 mm Hg, and increasing oxygen pressure improves fresh meat color stability. The packaging environment can substantially affect the oxygen pressure to which meat is exposed, and can thus profoundly affect the color stability of fresh meat. Packaging systems with atmospheres of high-oxygen partial pressure extend fresh meat color shelf life. Vacuum-packaged meats retain the ability to oxygenate when exposed to oxygen. An anoxic atmosphere in master packs, with subsequent display in oxygen-permeable packaging at retail, has allowed the development of central packaging. However, failure to completely remove oxygen (o1%) from these packages can result in pro-oxidative conditions and subsequent loss in color stability. The use of oxygen scavengers in which oxygen reacts with iron or lowmolecular weight organic compounds such as ascorbate has proven efficacious for maintaining the color shelf life in meats that are stored under oxygen-depleted atmospheres during subsequent retail display. Research into the biochemical mechanisms involved in heme pigment catalysis of lipid oxidation has shown that, during oxidation of MbO2, both superoxide anion and hydrogen peroxide are produced, which can further react with iron to form hydroxyl radicals that facilitate lipid oxidation. Generally, MbO2 shows higher prooxidant activity than MMb. However, MMb has been shown to react with hydrogen peroxide to form unstable hypervalent (Fe4+) myoglobin species, perferrylmyoglobin and ferrylmyoglobin. Perferrylmyoglobin is a transient species that autoreduces rapidly to the more stable ferrylmyoglobin. Under conditions found in fresh meat of usual pH values (5.5–5.8) ferrlymyoglobin also autoreduces rapidly to MMb. Both of these hypervalent myoglobin species have been shown to initiate lipid oxidation through abstraction of a hydrogen atom from fatty acids. In turn, the aldehydes arising from lipid oxidation can induce myoglobin pigment oxidation to MMb. Hence, many of the lipid (α-tocopherol)- and water-soluble (ascorbic acid, dipeptides) antioxidants used to reduce rancidity will also be efficacious for preserving meat color. Many of these antioxidants, rather than having a direct effect on the myoglobin, act to delay the production of lipid peroxidation breakdown

products such as peroxides, which can accelerate MbO2 oxidation.

Oxidation of Proteins Until recently, most research on oxidation and its effects in muscle foods concentrated on the lipid fraction, with limited study of protein oxidation (Pox). This may have been due to the greater susceptibility of lipids to oxidation, the generally later postmortem onset of Pox, and the challenges associated with measuring Pox in a complex meat matrix. However, the focus on Pox in relation to age-related disease in humans has provided methodologies and impetus to investigate Pox in the context of muscle foods. Although the basic mechanisms underlying Pox are still under investigation, both the amino acid side chains and peptide linkages of the protein backbone have been shown to be susceptible to reaction with free radicals in the presence of oxygen. Hence, oxidative changes to proteins include protein cross-linking, amino acid side chain modification, and protein fragmentation. The chemical mechanisms are similar to those that occur in lipid oxidation but are less complex, and fewer oxidation products have been reported to date. In general, unsaturated double bonds susceptible to oxidation occur infrequently in proteins as they are found in only the aromatic amino acids tryptophan, tyrosine, and phenylalanine, and in the heterocyclic amino acid histidine. Amino acids most susceptible to metal-catalyzed oxidation include those with nitrogen-containing functional groups (arginine, lysine, proline) that yield carbonyl residues, and sulphur-containing amino acids (methionine and cysteine) that form cross-links and yield sulphur-containing residues. The extent of Pox has been generally estimated by measuring the appearance of protein carbonyl compounds in muscle foods using the dinitrophenylhydrazine method. The loss of thiol groups in proteins from muscle foods, which is also a good indicator of oxidation, has been determined spectrophotometrically using Ellman’s reagent and, recently, with greater sensitivity, using a fluorescent reagent (ThioGlo®1). Theoretically, amino acids with reactive side chains that include an imidazole ring, indole ring, suflhydryl, thioesther, or amino group (tryptophan, histidine, lysine, cysteine, and arginine) are most susceptible to reaction with lipid peroxidation products. However, the role of lipid peroxidation products in the initiation of Pox is still a matter of debate. In a complex matrix such as meat there seems to be little doubt these processes are not entirely independent; and due to the earlier onset of lipid oxidation, it would seem that lipid peroxide products must have a role in promoting Pox. In addition, the interaction between lipid and Pox must be highly dependent on the species, muscle type, type of muscle food, and a host of other environmental moderators. Of interest is the suggestion that proteins, particularly the myofibrillar proteins, may themselves act as an antioxidant within muscle foods. Their ability to scavenge free radicals and chelate metal ions may provide protection to other susceptible compounds, including lipids and proteins. Research on the effect of Pox in muscle foods focused initially on changes to protein functionality during further

Spoilage, Factors Affecting | Oxidative and Enzymatic processing that results in alterations of the gel-forming ability, meat-binding ability, emulsification capacity, solubility, viscosity, or water-holding capacity of meat preparations. These changes in protein functionality can result in textural changes to meat products. However, the oxidative processes are complex and, depending on various intrinsic and extrinsic factors, may result in either improved or reduced functionalities. The intrinsic and extrinsic factors include the types of pro-oxidants or antioxidants, types of muscle or protein, specific protein side chains or amino acid residues located on the surfaces of protein molecules, the extent of oxidative modification, and the storage time. It has been suggested that mild-to-moderate protein modification results in improved protein functionality, whereas extensive alteration results in decreased functionality due to excessive aggregation and precipitation of the proteins. In the past decade, attention has been directed toward the consequences of Pox in fresh, whole muscle during processing, fabrication, and storage. The findings indicate that Pox may have a negative effect on juiciness, tenderness, and nutritional quality. Pox-induced increases in cross-linking of the myofibrillar proteins is thought to contribute to reduced juiciness and tenderness, although Pox-based inactivation of µ-calpain may also be involved (see Section Enzymatic Factors). Increased cross-linking of the myosin tail region can stabilize the myofibrillar structure and constrain myofibrillar swelling, resulting in decreased tenderness and juiciness of fresh meat stored under high-oxygen packaging. Conversely, increased Pox during drying and salting may contribute to the unique and preferred textural characteristics of dry-cured meats and salted fish. Increased hardness of pâtés and cooked sausages during refrigerated storage has also been ascribed to Pox-induced cross-linking. Pox may decrease the nutritional value of muscle foods through both depletion of essential amino acids and decreased digestibility of oxidized muscle proteins, although the science is not yet conclusive. Through modification of the oxidation state of the heme iron, Pox can also contribute to negative effects on meat color. In addition, the formation of carbonyls during Pox may impact odor and flavor, and may contribute significantly to the unique flavor of dry-aged meats.

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which can propagate oxidation. However, both catalase and glutathione peroxidase are active in converting peroxides into inactive derivatives, thereby preventing oxidative damage. In addition, glutathione peroxidase is capable of reacting directly with lipid peroxides, limiting oxidation. Species differences in antioxidant enzymes have been reported with higher activities of superoxide dismutase and glutathione peroxidase in beef4turkey4pork, whereas activities of catalase are higher in pork4beef4turkey. Some evidence exists that the inactivation of antioxidant enzymes through heating contributes to the development of WOF. However, when catalase and glutathione peroxidase were added back into cooked muscle, only 15% of the lipid peroxidation was inhibited. Because most enzymes are proteins, Pox may affect numerous enzyme-mediated processes in muscle foods. Perhaps the most attention to date has been given to the calpain enzyme system that plays a key role in postmortem tenderization. Irradiation of meat decreased tenderness and increased Pox in both the sarcoplasmic and myofibrillar fragments of meat, but the direct effect on µ-calpain was not measured. In contrast, storage under high oxygen also decreased tenderness but showed no inactivation of µ-calpain. Thus, although conclusive evidence that the µ-calpain enzyme undergoes Pox has not been obtained to date, this remains an active research area. There is also need for further understanding of the potential impact of Pox on other sarcoplasmic proteins.

See also: Chemical and Physical Characteristics of Meat: Adipose Tissue; Color and Pigment; Palatability. Conversion of Muscle to Meat: Color and Texture Deviations. Cooking of Meat: Flavor Development; Warmed-Over Flavor. Fish Inspection. On-Line Measurement of Meat Quality. Packaging: Modified and Controlled Atmosphere. Refrigeration and Freezing Technology: Applications; Thawing. Sensory Assessment of Meat. Spoilage, Factors Affecting: Microbiological

Further Reading Enzymatic Factors Enzymes, including lipoxygenases, peroxidases, and microsomal enzymes, which catalyze insertion of oxygen into polyunsaturated fatty acids with methylene interrupted dienes, have been identified in various animal tissues and contribute to enzyme-mediated oxidation of lipids. In contrast, phospholipases have been shown to inhibit lipid peroxidation by forming iron complexes with the free fatty acids liberated by hydrolysis of phospholipids in the membrane. Several cytosolic enzymes, including superoxide dismutase, catalase, and glutathione peroxidase, are active antioxidant enzymes in muscle. Superoxide dismutase controls the reactivity of superoxide anions and perhydroxyl radicals, both of which are involved in promotion of lipid oxidation. It also catalyzes the conversion of the superoxide anion to hydrogen peroxide. Hydrogen peroxide can be rapidly decomposed by transition metals to an extremely reactive hydroxyl-free radical,

Baron, C.P., Andersen, H.J., 2002. Myoglobin-induced lipid oxidation. A review. Journal of Agricultural and Food Chemistry 50 (14), 3887–3897. Brewer, S.M., 1998. What is “warmed-over flavour”? Pork quality factsheet. National Pork Board and the American Meat Science Association. Available at: http://www. porkboard.org (accessed 29.10.13). Chan, K.M., Decker, E.A., 1994. Endogenous skeletal muscle antioxidants. Critical Reviews in Food Science and Nutrition 34 (4), 403–426. Dave, D., Ghaly, A.E., 2011. Meat spoilage mechanisms and preservation techniques: A critical review. American Journal of Agricultural and Biological Science 6 (4), 486–510. Faustman, C., Sun, Q., Mancini, R., Suman, S.P., 2010. Myoglobin and lipid oxidation interactions: Mechanistic bases and control. Meat Science 86 (1), 86–94. Fox Jr., J.B., 1987. The pigments of meat. In: Price, J.F., Schweigert, B.S. (Eds.), The Science of Meat and Meat Products, third ed. Westport, CT: Food & Nutrition Press, Inc., pp. 193–216 (Chapter 5). Frankel, E.N., 1998. Lipid Oxidation. Dundee, Scotland: The Oily Press Ltd. Howe, P., Buckley, J., Meyer, B., 2007. Long-chain omega-3 fatty acids in red meat. Nutrition and Dietetics 64 (4), S135–S139. Huff-Lonergan, E., Zhang, W., Lonergan, S.M., 2010. Biochemistry of postmortem muscle − Lessons on mechanisms of meat tenderization. Meat Science 86 (1), 184–195.

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Leray, C., 2003. Cyberlipid center: Resource site for lipid studies. Available at: http://www.cyberlipid.org (accessed 29.10.13). Lund, M.N., Heinonen, M., Baron, C.P., Estévez, M., 2011. Protein oxidation in muscle foods: A review. Molecular Nutrition and Food Research 55, 83–95. Mancini, R.A., Hunt, M.C., 2005. Current research in meat color. Meat Science 71 (1), 100–121. Negre-Salvayre, A., Coatrieux, C., Ingueneau, C., Salvayre, R., 2008. Advanced lipid peroxidation end products in oxidative damage to proteins. Potential role in diseases and therapeutic prospects for the inhibitors. British Journal of Pharmacology 153 (1), 6–20.

Pearson, A.M., 1986. Physical and biochemical changes occurring in muscle during storage and preservation. In: Betchel, P.J. (Ed.), Muscle as Food. London, UK: Academic Press Inc., pp. 103–134 (Chapter 3). Schwimmer, S., 1981. Source Book of Food Enzymology. Westport, CT: AVI Publishing Co. Younathan, M.T., 1985. Causes and prevention of warmed over flavor. Proceedings of the Annual Reciprocal Meat Conference, vol. 38, pp. 74−80. Chicago, IL: National Live Stock and Meat Board. Available at: http://www.meatscience.org (accessed 29.10.13).

STUNNING

Contents CO2 and Other Gases Electrical Stunning Mechanical Stunning Slaughter: Immobilization

CO2 and Other Gases ABM Raj, University of Bristol, Langford, North Somerset, UK r 2014 Elsevier Ltd. All rights reserved. This article is a revision of the previous edition article by ABM Raj, volume 3, pp 1348–1353, © 2004, Elsevier Ltd.

Glossary Anoxia Severely reduced levels or complete lack of oxygen. Breathlessness A sense or feeling of unable to breath. Bronchoconstriction Narrowing of bronchi/respiratory tract.

Introduction In most of the developed countries, it is a statutory requirement that all animals, including poultry, slaughtered for human consumption are rendered immediately unconscious and that they remain so until death supervenes through loss of blood. Because the effect of a stunning method is momentary, the onus of preventing resumption of consciousness following stunning relies on the efficiency of the slaughter procedure, i.e., the prompt and accurate severance of blood vessels supplying oxygenated blood to the brain. By contrast, killing animals with gases can eliminate the chances of recovery of consciousness. Regulations governing the welfare of animals (during stunning or killing) in many countries, including the UK, prescribe certain gas mixtures for stunning/killing of pigs and domestic poultry. The relative merits of various gas mixtures used for stunning pigs and poultry are addressed in this article. Stunning of farmed fish using gas mixtures is also considered.

Reason for Use of Gas Stunning Among the farm animals slaughtered for human consumption, pigs are arguably the most susceptible to stress during preslaughter handling and stunning. Electrical stunning is commonly used for rendering pigs unconscious before slaughter. With electrical stunning, some form of restraint

Encyclopedia of Meat Sciences, Volume 3

Dyspnea Difficulty in breathing. Hypercapnea Elevated levels of carbon dioxide. Hyperventilation Increased rate and/or depth of breathing. Hypoxia Reduced oxygen levels.

(lifting or squeezing) is necessary to facilitate ideal placement of the stunning tongs and to achieve an effective stunning. Research has shown that isolation of individual animals from their pen mates and the application of any form of restraint can be distressing to pigs. By contrast, stunning of pigs with gases does not require a restraint and modern gas stunning devices involve killing in small groups. For example, pigs are loaded into a cage or cradle and lowered into a well, or passed through a purpose-built tunnel containing gas mixtures. Multiple-bird electrical water bath stunning is the most common and cheapest method of rendering poultry unconscious before slaughter under commercial conditions, where high throughput rates (up to 220 birds per minute) are required. Under this system, conscious birds are hung upside down on a moving metal shackle line (process known as shackling) and passed through an electrified water bath, such that the current flows through the whole body toward the earthed shackle. There are many welfare concerns associated with the commercial electrical water bath stunning systems, such as unnecessary pain and suffering caused by uncrating, shackling, prestunning electric shocks, inadequate stunning, and recovery of consciousness leading to live birds entering the scald tanks. Owing to the complexity of multiple-bird electrical water bath stunning systems, it will be difficult to resolve the bird welfare problems. However, killing of poultry using gases, while the birds are still in their transport containers, will eliminate the problems associated with handling of live birds at the primary processing plant and electrical water bath

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stunning systems. This concept was originally proposed in 1982 by the Farm Animal Welfare Council in the UK. All the gas stunning systems now operating in Great Britain involve killing in transport crates. Some gas stunning systems operating in Europe, however, involve tipping of live birds from transport modules on to a conveyor belt that passes through a gas stunning tunnel. There are gas stunning systems operating in North America that involve shackling of conscious poultry before stunning. Needless to say, the latter systems have failed to fully utilize the welfare benefits of gas stunning.

Gas Mixtures Evaluated for Stunning/Killing Although a number of scientific and commercial establishments evaluated the commercial feasibility of stunning pigs and poultry with gases as early as 1950, the animal welfare and carcass and meat quality issues were addressed only during the latter part of the twentieth century. In this regard, most of the research and development was carried out in Scandinavian countries, Spain, and the UK. Gas mixtures investigated so far have included: • 40–90% by volume of carbon dioxide in air (hypercapnia). • Mixtures containing a minimum of 30% by volume of carbon dioxide and 20–30% by volume of added oxygen in air (hypercapnic hyperoxia). • Mixtures of argon and nitrogen with 2% by volume of residual oxygen in air (anoxia). • A mixture of less than 30% by volume of carbon dioxide in argon or nitrogen or both with up to 5% by volume of residual oxygen (hypercapnic anoxia). The normal atmospheric concentration of carbon dioxide is 0.003% by volume; however, the gas is cheaply and readily available as a by-product of the chemical/fertilizer industries. Argon and nitrogen occur naturally and can be separated from atmospheric air. The atmospheric concentration of argon is 0.94% by volume and that of nitrogen is 79% by volume, and thus nitrogen is cheaper than argon. Another advantage of using nitrogen is that it can be separated from atmospheric air in any part of the world with the minimum of cost and impact on the environment. Nitrous oxide has been used experimentally to stun pigs, but owing to toxicity on chronic exposure in humans, it is not used commercially.

Mechanisms of Induction of Unconsciousness Carbon dioxide induces unconsciousness through inhibition of neurons. This mechanism is closely related to the fall in pH of the cerebrospinal fluid (CSF), which bathes the brain and spinal cord. It has been reported that unconsciousness begins when the CSF pH falls below 7.1 and reaches a maximum at pH 6.8. The level of γ-aminobutyric acid (GABA), which is the major inhibitory amino acid neurotransmitter, has been known to increase during distress and anxiety; it is not certain whether the increase in GABA level is due to the stress of induction of unconsciousness with this gas or a physiological

mechanism involved in carbon dioxide-induced neuronal inhibition. Inhalation of carbon dioxide does not lead to a reduction in the blood oxygen level and, therefore, anoxia does not accompany the inhalation of carbon dioxide at concentrations required for stunning animals. In addition, the anesthetic effect of carbon dioxide is independent of residual oxygen in the breathing mixture. For example, a mixture of 40% carbon dioxide and 30% oxygen will also render animals unconscious. The time to onset of unconsciousness in pigs is related to concentrations of carbon dioxide between 40% and 70% by volume in air. Increasing the concentration of carbon dioxide in an air mixture above 70% by volume does not reduce the time to loss of consciousness greatly. However, the times to loss of consciousness in terrestrial poultry species seem to be very similar during exposure to 40% by volume or more of carbon dioxide in air and are rather prolonged when 20% by volume or more of oxygen is added to the mixture. The time to onset of death in both species is related to the concentration of carbon dioxide and the duration of exposure to the gas. Gas mixtures containing carbon dioxide and 30% by volume or more of oxygen do not induce death and therefore require a killing procedure (e.g., further exposure to a high concentration of carbon dioxide in air). In general, hypoxia or anoxia occurring as a result of the inhalation of argon or nitrogen induces unconsciousness by depriving the brain of oxygen. For example, it has been established that cerebral dysfunction occurs in mammals when the partial pressure of oxygen in cerebral venous blood falls below 19 mmHg. Brain oxygen deprivation leads to accumulation of extracellular potassium and a metabolic crisis as indicated by the depletion of energy substrates and accumulation of lactic acid in the neurons. These effects can occur within a matter of few seconds of inhalation of an anoxic agent. However, it is worthy of note that the survival times of various parts of the brain may differ according to the regional oxygen consumption rate. For example, the survival time of the cerebral cortex is considerably shorter than that of the medulla, in which the respiratory center is located. Normal brain activity may be restored in anoxia-stunned animals if oxygen is administered or they are allowed to breathe atmospheric air. Inevitably, the recovery of consciousness in these animals is rapid. It is therefore a statutory requirement in the UK that animals must be held within the gaseous atmosphere until they are dead. Argon and nitrogen, along with xenon, are frequently referred to as inert gases. However, in contrast to argon or nitrogen having anesthetic properties under hyperbaric conditions, xenon is an anesthetic gas under normobaric conditions. It has been reported that inhalation of 80% xenon and 20% oxygen induced unconsciousness in humans via the inhibition of N-methyl-D-aspartate (NMDA) receptor channels, which are essential for maintaining neuronal excitation during the conscious state. Interestingly, induction of unconsciousness with xenon, argon, nitrogen, and nitrous oxide (‘laughing gas’) has frequently been described by humans as a euphoric or very pleasant way of losing consciousness, and this may be due to the effects of those gases on NMDA receptor channels. It is worth noting that the effects of a number of modern analgesics, sedatives, and anesthetics are also mediated via NMDA receptor channels in the brain.

Stunning | CO2 and Other Gases

Time to Onset of Unconsciousness during Exposure to Gas Mixtures Although ‘unconsciousness’ has different interpretations, from the stunning and slaughter point of view it can be suggested to be ‘a state in which the ability of the brain to process sensory stimuli, including pain, is lost.’ In this regard, the time to loss of somatosensory-evoked potentials (SEPs) in the brain, induced by electrically stimulating a peripheral nerve, has been determined during exposure of pigs and poultry species to various gas mixtures. The time to loss of SEPs is found to be rapid with argon-induced anoxia. By contrast, the time to loss of brain responsiveness during exposure to carbon dioxide in air can be relatively long and highly variable. Inhalation of a mixture of 30% by volume of carbon dioxide in argon or nitrogen seems to have an additive effect on the brain in species that are known to be resilient to the effects of carbon dioxide or anoxia alone (e.g., waterfowl).

Welfare Concerns of Gas Stunning

Time (min:sec)

The induction of unconsciousness with gas mixtures should be differentiated from asphyxia. The physiological definition of asphyxia implies a physical separation of the upper respiratory tract from the atmosphere. For example, drowning involves water as a separating medium, strangulation leads to constriction of the trachea, and choking is due to obstruction in the respiratory tract. Suffocation is frequently used as a synonym for asphyxia. Unlike other established stunning methods, exposure of animals to gas mixtures does not produce an immediate loss of consciousness. It is therefore important to ensure that the induction of unconsciousness with gas mixtures does not compromise animal welfare. It is known that breathlessness (dyspnea) can occur as a result of changes in the blood oxygen or carbon dioxide levels. For example, exercise induces breathlessness through the gradual increase in blood carbon dioxide concentration. However, inhalation of high concentrations of carbon dioxide results in rapid increases in blood carbon dioxide concentration, and this is more effective in producing dyspnea. It is also worth noting that the severity of breathlessness depends upon the rate at which the blood carbon dioxide increases. It has been reported that, in humans, an increase in blood carbon dioxide tension of 5 mmHg above normal will stimulate respiration, whereas the blood oxygen tension has to decrease

by approximately 60 mmHg from the normal level before hypoxia stimulates the respiratory centers in the brain. It is therefore apparent that hypercapnia is a more potent respiratory stimulant than is hypoxia. Further evidence to support these concerns also emerges from studies involving pigs and poultry. Aversion to the initial exposure to argon-induced anoxia or carbon dioxide has been used (e.g., passive avoidance tests in the presence of a reward) to determine the relative merits of gas mixtures. The results of this study clearly indicated that pigs do not show any aversion to 90% argon in air; the majority (75%) of pigs did not show aversion to 30% carbon dioxide in air, whereas the majority (88%) of pigs avoided an atmosphere containing a high (480%) concentration of carbon dioxide in air. In this study, pigs that found carbon dioxide aversive withdrew their heads immediately on exposure and did not attempt again to obtain the reward offered. However, a minority of pigs made repeated efforts to obtain the reward. It has been reported that human volunteers also find inhalation of 40% by volume of carbon dioxide extremely unpleasant. It is therefore not surprising to note that pigs, being phylogenetically close to humans, also experience the same aversion. Fasting pigs for up to 24 h before exposure to 90% carbon dioxide in air did not overcome the aversion. Similarly, a considerable proportion of chickens and turkeys have been reported to avoid atmospheres containing high concentrations (40% by volume or more) of carbon dioxide in air. Passive avoidance tests also showed that pigs spent similar times feeding in air and under anoxia (Figure 1) and, as would be expected, several of them lost consciousness (as determined from the occurrence of loss of posture) while eating apples presented in the anoxic atmosphere. Recent research carried out in an experimental slaughterhouse in Spain demonstrated that pigs show more aversion to gas mixtures containing nitrogen and either 15% or 30% carbon dioxide by volume than 90% argon by volume in air. It is thus evident that the initial exposure to a high concentration of carbon dioxide is extremely aversive and, given a free choice, animals will avoid such an atmosphere. This is probably because carbon dioxide is an acidic gas and is pungent to inhale in high concentrations. Indeed, carbon dioxide gas has been used to stimulate the nasal mucous membrane in order to induce pain-evoked responses in the brain. In addition, the severity of respiratory sounds occurring during the induction of unconsciousness in pigs (until they

3.00 2.50 2.00 1.50 1.00 0.50 0.00 Air

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Anoxia

90% CO2 Treatments

Figure 1 The average time (maximum 3 min) spent by pigs on feeding apples in various atmospheres.

90% CO2 after overnight fast

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Subjective score (0 to 3)

3.00 2.50 2.00 1.50 1.00 0.50 0.00 Air

2% O2

40% CO2

50% CO2

80% CO2

90% CO2

Treatments Figure 2 The severity of respiratory distress occurring in pigs during the induction of unconsciousness with gas mixtures.

lose posture) with gas mixtures has been subjectively rated and used to ascertain respiratory distress. It has been reported that exposure to 90% argon induced minimal respiratory distress, whereas, exposure to 40–90% by volume of carbon dioxide in air induced severe respiratory distress. Exposure to 30% by volume of carbon dioxide in an argon mixture induced moderate distress. Some pigs that were exposed to less than 70% carbon dioxide in air showed escape attempts. By contrast, during exposure to argon-induced anoxia, pigs lost posture without any evidence of behavioral arousal or escape attempts. See Figure 2. Research carried out in an experimental slaughterhouse using a dip-lift system indicated that the incidence of pigs showing retreat and escape attempts was lower in 90% argon by volume in air than in the gas mixtures containing nitrogen and 15% or 30% by volume of carbon dioxide. In poultry species, however, high concentrations of carbon dioxide induce severe head shaking, gasping, sneezing, and vocalizations, which can be considered as indicators of distress. This interpretation is based on the fact that these behaviors also occur during respiratory disease. On the basis of the above evidence, it is suggested that anoxia is the best option on animal welfare grounds. The use of a mixture containing low concentrations (o30% by volume) of carbon dioxide in argon or nitrogen or both would appear to be better than using a high concentration of carbon dioxide in air. However, those who wish to promote carbon dioxide for stunning argue that the cumulative stress associated with conventional electrical stunning methods can be greater than the stress of induction of unconsciousness with this gas. It is also claimed that the increased rate and depth of breathing occurring during carbon dioxide stunning of pigs enable them to breathe more of this gas and lose consciousness rapidly. It could also be argued that the cumulative stress caused to poultry during electrical water bath stunning is more than that would occur during stunning with carbon dioxide. On the basis of these arguments, carbon dioxide is widely used for stunning pigs and poultry. Control of the temperature and humidity of the carbon dioxide in the stunning atmosphere could improve the welfare of animals. For example, in humans, nasal breathing of air increases the respiratory system's ability to warm and humidify the inspired air compared to oral breathing. By contrast, oral breathing, in particular during exercise-induced hyperventilation, results in

drying and cooling of the upper respiratory tract, and this is one of the causes of exercise-induced asthma or bronchoconstriction. Under these circumstances, inhalation of warm and humidified air helps to alleviate distress, and this concept is widely used in human artificial respirators. Because animals exposed to carbon dioxide gas also show gasping (oral breathing), it is thought that administration of a warm and humidified gas mixture will help to reduce the severity of distress. Commercial farming of several species of fish for human food has become popular in recent years. Traditionally, fish would be taken out of the water manually using nets or mechanically using pumps and placed in air or on ice, which is considered to be equivalent to asphyxiation in terrestrial vertebrates. Owing to the concern for their welfare at slaughter, the use of gas mixtures, especially carbon dioxide, for stunning salmon, trout, seabream, and seabass under commercial farming conditions has also been developed, at least in Europe. Carbon dioxide is highly soluble in water. Under commercial conditions, carbon dioxide is bubbled into water (sea or fresh water, depending upon the species of fish) contained in tanks until the water becomes saturated with the gas. Batches of fish are then placed in the CO2-saturated water and held until they become completely sedated or motionless. However, research has shown that fish find immersion into CO2-saturated water aversive, as indicated by rapid swimming and making escape attempts.

Commercial Implications Experiments with the carbon dioxide stunning of pigs have shown that exposure to a minimum of 70% carbon dioxide for 90 s results in stunning; therefore sticking (bleeding or exsanguination) should be performed as soon as possible (e.g., ideally within 15 s of exiting the gas) to prevent resumption of consciousness. When the duration of exposure to this level of carbon dioxide is increased, the incidence of death also increases. Under high-throughput conditions, exposure of pigs to a minimum of 90% by volume of carbon dioxide in air for 3–5 min results in death in the majority of pigs, which can be recognized from the presence of dilated pupils and absence of gagging (rudimentary respiratory activity) at the exit from the gas. In Denmark, where almost all pigs are stunned using carbon dioxide, a comprehensive automatic system for driving

Stunning | CO2 and Other Gases large groups of pigs (15–16 pigs) from the lairage to the point of stunning, dividing them into small groups (e.g., 5–6 pigs) and loading them onto a lift, which is lowered into a carbon dioxide stunning unit, has been developed. In comparison with the conventional pig handling and loading systems and carbon dioxide stunning units, this group handling and stunning system is far better on animal welfare grounds. It has been reported that exposure of pigs to either argoninduced anoxia or the carbon dioxide–argon mixture for 3 min resulted in satisfactory stunning; however, bleeding should commence within 15 s to avoid resumption of consciousness. A 5 min exposure to these gas mixtures followed by bleeding within 45 s prevented carcass convulsions during bleeding. The results also showed that exposure of pigs to argon-induced anoxia or the carbon dioxide–argon mixture for 7 min resulted in death in the majority of pigs. Owing to the prolonged exposure time required to kill pigs with anoxia, it is not used under commercial conditions. However, further research and development is needed to evaluate the feasibility of inducing unconsciousness with anoxia and then killing pigs by other means (e.g., induction of cardiac arrest in unconscious pigs using an electric current). Chickens and turkeys can be killed with a minimum of a 2 min exposure to 50% by volume carbon dioxide in air, 90% by volume of argon or nitrogen in air, and a mixture containing less than 30% by volume of carbon dioxide in argon or nitrogen. The Welfare of Animals (Slaughter or Killing) Regulations in the UK approved the use of a minimum of 70% by volume of carbon dioxide in air for killing pigs. However, on bird welfare grounds, this regulation does not allow the use of carbon dioxide for killing domestic poultry, except for disease-control purposes. Instead, two other gas mixtures have been approved for killing domestic poultry intended for human consumption: • Argon, nitrogen, or other inert gases, or any mixture of these gases, in atmospheric air with a maximum of 2% oxygen by volume. • Any mixture of argon, nitrogen, or other inert gases with atmospheric air and carbon dioxide provided that the carbon dioxide concentration does not exceed 30% by volume and the oxygen concentration does not exceed by 2% by volume. However, the European Slaughter Regulation 1099/2009, which comes into force from January 2013, permits the use of: 1. Direct or progressive exposure of conscious pigs to a gas mixture containing more than 40% carbon dioxide for pigs. 2. Direct or progressive exposure of conscious pigs and poultry to an inert gas mixture such as argon or nitrogen leading to anoxia. 3. Direct or progressive exposure of conscious pigs and poultry to a gas mixture containing up to 40% of carbon dioxide associated with inert gases leading to anoxia. 4. Successive exposure of conscious birds to a gas mixture containing up to 40% of carbon dioxide, followed when they have lost consciousness, by a higher concentration of carbon dioxide. In general, gas stunning/killing of pigs and poultry results in better carcass and meat quality than other established stunning methods. In comparison with electrical stunning, gas

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stunning or killing can reduce the incidence of broken bones in carcass and hemorrhaging in muscles. However, stunning with gas mixtures containing 40% by volume or more of carbon dioxide tends to retard the rate of rigor development and, hence, tenderness development. By contrast, stunning of pigs and poultry with argon and nitrogen mixtures or a mixture containing less than 30% by volume of carbon dioxide in argon or nitrogen mixture accelerates the rate of postmortem rigor development and tenderization of meat. This is found to be at least as effective as electrical stimulation of carcasses, especially in poultry. Therefore, these gas mixtures provide an opportunity for poultry processors to portion or separate breast muscles soon after chilling (in less than 2 h postmortem) without inducing toughness, provided the muscle temperature is also reduced rapidly by the use of an appropriate chilling method. However, convulsions occurring as wing flapping after the loss of consciousness in poultry can increase the incidence of dislocated or broken wing bones. Owing to this and the cost of argon, the poultry industry would prefer to use gas mixtures causing less of this quality problem, especially methods involving exposure to low or gradually increasing concentrations of carbon dioxide in air as these methods have been known to cause very little or no wing damage in the carcasses. Irrespective of the species of animals involved, the everdecreasing competition in the fields of stunning equipment manufacturing and gas distillation and distribution are disconcerting on economic grounds.

Conclusions In general, gas stunning of pigs in small groups and of poultry in transport crates can benefit animal welfare and improve carcass and meat quality. Anoxia induced with argon, nitrogen, and any mixtures of inert gases would appear to be the best option on animal welfare and carcass and meat quality grounds. By contrast, the induction of unconsciousness with carbon dioxide could be distressing to animals, and therefore the meat industry should be encouraged to seek potential alternatives.

See also: Carcass Chilling and Boning. Conversion of Muscle to Meat: Aging; Glycolysis; Rigor Mortis, Cold, and Rigor Shortening; Slaughter-Line Operation and Pig Meat Quality. Environmental Impact of Meat Production: Primary Production/Meat and the Environment. Preslaughter Handling: Welfare Including Housing Conditions. Slaughter-Line Operation: Poultry. Stunning: Mechanical Stunning

Further Reading Dalmau, A., Llonch, P., Rodreguez, P., et al., 2010. Stunning pigs with different gas mixtures: Gas stability. Animal Welfare 19, 315–323. Dalmau, A., Rodreguez, P., Llonch, P., Velarde, A., 2010. Stunning pigs with different gas mixtures: Gas stability. Animal Welfare 19, 325–333. EFSA (European Food Safety Authority), 2012. Scientific Opinion on the electrical requirements for water bath stunning equipment applicable for poultry. EFSA Journal 10(6), 2757 (80 pp).

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Gillies, J.A. (Ed.), 1965. A Text Book of Aviation Physiology. Oxford: Pergamon Press. Gregory, N.G., 1998. Animal Welfare and Meat Science. Wallingford, Oxon: CABI Publishing. Llonch, P., Dalmau, A., Rodreguez, P., Manteca, X., Velarde, A., 2012. Aversion to nitrogen and carbon dioxide mixtures for stunning pigs. Animal Welfare 21, 33–39. Raj, A.B.M., 1999a. Behaviour of pigs exposed to mixtures of gases and the time required to stun and kill them: Welfare implications. The Veterinary Record 144, 165–168. Raj, A.B.M., 1999b. Effects of stunning and slaughter methods on carcass and meat quality. In: Richardson, R.I., Mead, G.C. (Eds.), World Poultry Science Association (UK Branch) Symposium Series, Poultry Meat Science 25, 231−254. Raj, A.B.M., 2006. Recent developments in stunning and slaughter of poultry. World's Poultry Science Journal 62, 467–484.

Raj, M., Tserveni-Gousi, A., 2000. Stunning methods for poultry. World's Poultry Science Journal 56, 291–304. Scientific Opinion of the Panel on Animal Health and Welfare on a request from the European Commission, 2009a. Welfare aspect of the main systems of stunning and killing of farmed seabass and seabream. The EFSA Journal 1010, 1–52. Scientific Opinion of the Panel on Animal Health and Welfare on a request from the European Commission, 2009b. Welfare aspect of the main systems of stunning and killing of farmed Atlantic salmon. The EFSA Journal 1012, 1–77. Scientific Opinion of the Panel on Animal Health and Welfare on a request from the European Commission, 2009c. Species-specific welfare aspects of the main systems of stunning and killing of farmed rainbow trout. The EFSA Journal 1013, 1–55. Warriss, P.D. (Ed.), 2000. Meat Science: An Introductory Text. Wallingford, Oxon: CABI Publishing.

Electrical Stunning E Lambooij, Wageningen UR Livestock Research, The Netherlands r 2014 Elsevier Ltd. All rights reserved. This article is a revision of the previous edition article by E Lambooij, volume 3, pp 1342–1348, © 2004 Elsevier Ltd.

Glossary Cardiac arrest A process that occurs when the heart ceases to function. It can occur, for example, through ventricular fibrillation. Clonic muscle spasms A series of alternating muscular contractions and relaxations. Consciousness A state of the mind that includes subjectivity, awareness, the ability to experience or to feel, wakefulness, and the executive control system of the mind. Electroencephalogram (EEG) A measure of the electrical activity of the brain. Electronarcosis or electroanesthesia A state of unconsciousness achieved by application of an electric current.

Introduction

Generalized epileptiform activity The seizure of grand mal epilepsy, consisting of a loss of consciousness and generalized tonic convulsions followed by clonic convulsions. Neurotransmitters A group of chemicals in the brain responsible for brain/nerve function. They include gamma amino-4-butyric acid (GABA), vasopressin, oxytocin, glutamate, and aspartate. Slaughter The process of exsanguination or bleeding that involves sticking (severance of the brachiocephalic trunk at the thoracic inlet in cattle and pigs) and cutting both the carotid arteries in the upper neck (sheep, goat, and poultry). Tonic muscle spasm A sudden, abnormal, involuntary muscular contraction consisting of a continued muscular contraction.

responses) to assess unconsciousness and insensitivity are recommended.

Stunning Process All animals, including poultry and fish, should be protected from anthropogenic excitement, and pain or suffering during transport, lairage, restraint, stunning, slaughter, or killing. Research in bird-, mammal-, and fish-slaughtering industries has linked improvements in animal welfare to improvements in meat quality. Stunning of animals is applied to induce a state of unconsciousness and insensibility of sufficient duration to ensure that the animal does not recover before exsanguination results in death. It is accepted that unconsciousness and insensibility should be induced immediately during stunning to minimize detrimental effects on animal welfare and meat quality. Electrical stunning, also referred to as electronarcosis or electroanesthesia, is widely used all over the world in slaughterhouses on farmed animals such as cattle, sheep, pigs, poultry, and fish. Electrical stunning involves passing of an electric current of sufficient magnitude through the head of an animal such that a generalized epileptiform activity is induced in the brain (grand mal seizure-like state). In humans, generalized epileptiform activity involving both the cerebral hemispheres is always accompanied with unconsciousness, and therefore sentient animals are also considered to be unconscious and insensitive following electrical stunning. The epileptic process is characterized by rapid and extreme depolarization of the resting membrane potential of neurons in the brain. Nevertheless, behavioral and clinical signs of recovery are not always sufficient for the assessment of the effectiveness of electrical stunning. Therefore, the use of electroencephalogram (EEG) recordings alongside responses to stimuli (visually evoked and somatosensory evoked

Encyclopedia of Meat Sciences, Volume 3

History Early in the nineteenth century scientists experimented with electricity in order to produce a state of anesthesia in animals and man, and later in the twentieth century, on animals to render them unconscious and insensible before slaughter. Most of the work in this connection was done in Germany, France, The Netherlands, and the USA. Leduc found that a constant current, which was rhythmically interrupted 90 times per second using a voltage of 5−20 V, was able to produce a comatose-like narcosis in rabbits. In other experiments on himself, his motor functions were paralyzed, whilst higher cerebral functions were not disrupted, but analgesia was present. Small animals showed tonic spasms before clonic contractions, which were often followed by convulsions when applying 300 mA on the head. Many meat hygienists came to the conclusion that the animals were unconscious because of the absence of the corneal reflex. It is clear that the conjunctival reflex, i.e., shutting of the eyelids after the conjunctiva was touched, was only possible provided that the eyelids were free to react. Because the eyelids were brought into tonic spasms as soon as the circuit was closed, the reflex was prevented. In this condition, absence of the reflex did not mean anything as regards the condition of the central nervous system, i.e., the brain. It was claimed that the ‘electrolethaler,’ which was designed for slaughter animals, was humane, instantaneous in action, economic in use, causing no blood splashing in the meat, safe, and ensured complete bleeding. The electrodes were placed behind the ears for a few seconds, and it was recommended to

doi:10.1016/B978-0-12-384731-7.00154-9

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place the electrodes as a second application on the head and back of the animal for 15−30 s. The voltage applied was 30−70 V. It was claimed that farm animals such as pigs, sheep, and calves were unconscious after the application of current. Fractures in the vertebrae of the carcasses were found and believed to be due to the sudden contraction of muscles.

Brain Stimulation Anesthesia Since the end of the past century, many investigations have been performed on electroanesthesia in animals and man. The anesthetic effect is brought about immediately with the onset of the flow of sufficient electric current through the brain, and the recovery is also very rapid after the end of electrical stimulation. In veterinary medicine, electroanesthesia might be used because it represents a simple, completely controllable, and low-cost method of anesthesia. During electroanesthesia, unconsciousness may be present but without a general epileptiform insult. It has been suggested that the ascending activating influence of the reticular formation of the brain stem suppress responses of the telencephalon or cortex (the seat of consciousness) during current delivery. Another suggestion is that the administered current interferes sufficiently with neuronal function at the thalamic (midbrain) level to cause anesthesia. It has also been observed that overt behavioral unconsciousness or loss of somatosensory potentials can occur without the development of polyspike activity in the EEG in sheep and poultry, respectively, when extremely high currents (almost 10 times than that is necessary to achieve effective stunning) are applied during stunning.

Stunning Electroanesthesia is widely used for the stunning of slaughter animals. The amounts of current necessary to stun various species of farmed animals are presented in Table 1. Effective electrical stunning can be ascertained from the occurrence of generalized epileptiform activity in the brain by using EEG. Generalized epileptiform EEG consists of relatively small waves increasing in amplitude in the tonic phase and decreasing in frequency in the clonic phase to result ultimately in a period of strong depression of electrical activity in pigs, sheep, calves, and poultry (Figure 1). Several studies involving sheep, in which neurotransmitters have been measured, coupled with pharmacological experiments, suggest the general epileptiform insult induced by an electrical stun is dependent on the release of vasopressin, oxytocin, glutamate, aspartate, and gamma amino-4-butyric acid (GABA). The first phase induced by the stun produces the tonic phase through the release of the excitatory neurotransmitter glutamate. This is followed by the release of GABA that provides a period of analgesia and also assists in the recovery if the animal is not slaughtered. The observed behavior of a general epileptiform insult is characterized by a phase of tonic muscle spasm followed by a phase of clonic muscle spasms and ultimately an exhaustion phase with muscle flaccidity. An eye reflex cannot be used as an indicator, because the reflex is blocked during the tonic phase

Table 1 Recommended minimal current for electrical stunning of poultry, ruminants, pigs, and fish Species

Head-only

Water-bath/water tank

Broiler Turkey Ostrich Duck and geese Quails Cow Calf Sheep and goat Pigs Eel Trout African catfish Carp Salmon Cod Turbot Tilapia Sea bass

240 mA 400 mA

100 mAo200 Hz−1 250 mAo200 Hz−1 500 mA 130 mAo200 Hz−1 45 mAo45 Hz−1

1.28 A 1.25 A 1.0 A 1.3 A 600 mA 500 mA 630 mA 240 mA

0.64 A dm−2 1.6 A dm−2 0.14 A dm−2 2.5 A dm−2 3.2 A dm−2 1.0 A dm−2 4.3 A dm−2

Head to body

1.0 A 1.0 A

570 mA 670 mA

and may occur spontaneously during the clonic phase. In sheep as well as in other mammals the extensors are stronger than the flexors that caused the extension. During head-only stunning, broilers may display wing flapping during and after stunning, which is sometimes intensive. Fish, which were able to move freely, initially showed limited tonic/clonic cramps, followed by heavy clonic contractions combined with uncoordinated movements or turning aside. The flexors and extensors in fish are considered to be equal in strength, which may explain the observation of limited tonic and clonic cramps. The most common electrical stunning method for livestock uses a frequency of 50 Hz alternating current (AC) with sinusoidal waveform. The frequency can be as high as 1800 Hz, and the waveform can be square or rectangular. High-frequency electrical stunning can induce epileptiform activity in the brain; however, relatively higher amounts of current are necessary to induce epileptiform activity and the duration of unconsciousness also shorter than those with 50 Hz. A sufficiently prolonged period of unconsciousness and insensibility (e.g., 40 s) is necessary to facilitate exsanguination (bleeding out) and onset of death in unconscious animals. In this regard, a bipolar sine or square wave is found to be more effective than monopolar-pulsed direct currents. In ‘head to body’ stunning involving passage of a 50 Hz sine wave alternating current simultaneously through the brain and heart, the animal may die due to a heart failure, which is recordable on an electrocardiogram (ECG). The heart failure results in loss of blood pressure and lack of oxygen to the brain and affects the characteristics of general epileptiform insult. Transcranial magnetic stimulation (TMS) is a recently developed noninvasive technique used in human psychiatry to treat depression with slowly repeated pulses to the frontal lobe or to induce seizures. A study was done to determine whether or not TMS with an adapted coil has potential for further development as a noninvasive stunning method for broilers and

Stunning | Electrical Stunning

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Stunning 100 µv

1s

Figure 1 Trace of the EEG before and during a general epileptiform insult. The relatively small waves (initial phase) became larger (tonic phase) with an increase in amplitude and a decrease in frequency, followed by a period of strong depression of electrical activity (exhaustion phase) and recovery.

rabbits but further research and development is needed to optimize parameters.

vessels supplying oxygenated blood to the brain. For example, sticking in cattle and pigs involves severance of the brachiocephalic trunk at the thoracic inlet and cutting both the carotid arteries in the upper neck of sheep, goat, and poultry.

Ethics First, stunning of animals is applied to induce a state of unconsciousness and insensibility of sufficient duration to ensure that the animal does not recover before death occurs via exsanguination. Second, stunning should produce sufficient immobility to facilitate safe shackling, hoisting, and exsanguination of animals. It is generally stated that unconsciousness should be induced, as soon as possible without imposing a detrimental effect on the welfare of the animal and the meat quality. For the application of stunning methods, it is necessary to confine or restrain the animal and to position it for stunning. The effectiveness of any method of preslaughter stunning can be seriously impaired by improper use of the restraining device on the animal and by preslaughter stress. Stress before slaughter increases some neurotransmitters, which may affect the poststun reflexes and unconsciousness. Combining head-only stunning with exsanguination has a synergistic effect on the release of glutamate and aspartate, which increases the duration of unconsciousness and insensibility. Sticking (also referred to as slaughter, exsanguination, or bleeding) following a stun should be carried out as promptly as possible when using head-only stunning as it takes time depending on the species before brain responsiveness is lost following sticking. It is widely recognized that inducing a cardiac arrest at stunning has distinct welfare advantages: (1) it results in a rapid loss of brain function, (2) it ensures that the animal will not regain consciousness, and (3) it does not depend on the slaughter man performing an accurate stick. Sticking should involve severance of blood

Meat Quality Various stunning methods and electrical parameters have been reported to have a different effect on postmortem rigor development and subsequent meat quality. The postmortem metabolism is largely a consequence of indirect stimulation through nervous pathways. Electrical stunning of lambs for 3−4 s can influence the pH measured in the loin and some other muscles. This is also the case in pork, and it may result in pale soft exudative meat, which is not necessarily related to genotype. In chickens, high-current electrical whole-body stunning at 100 mA and above resulted in higher initial muscle pH than nonelectrically stunned birds or birds stunned with 50 mA or less. Breast muscle shear values of birds wholebody stunned with currents lower than 100 mA were lower than or similar to, depending on the deboning time, stunning with currents higher than 100 mA. Broken vertebrae can occur in pigs stunned with head-toback electrode positioning if the voltage and the current are too high. A satisfactory stun with a minimum of fractures is obtainable when using 1.3 A with head-to-back stunning systems. Sinusoidal alternating currents of 50 Hz have a large stimulatory effect on skeletal muscles, which can be reduced by increasing the current frequency to an extent that prevents the occurrence of broken backs. The prevalence of broken vertebrae and pelvises could be reduced to zero by increasing the frequency from 50 to 1500 Hz when stunning head-toback with 300 V for 3 s. The drawback of this approach is that

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Figure 2 Hemorrhages in the muscles of the ham.

the effect on fibrillating the heart is also reduced. However, it might be possible to find an optimum combination of frequencies and current, and electrode position that stuns the pig and fibrillates the heart with minimum of damage to the carcass and meat. Hemorrhaging in major muscles and surrounding tissues results in a decrease in the quantity (trimming) and quality of meat products, and hence causes economic losses to the meat industry. Hemorrhages can be induced by stunning; however, the underlying mechanism is considered to be multifactorial. The morphology of hemorrhages investigated was dependent on the tissue in which they occurred. In the pectoral muscles, extravasating blood was found to follow the direction of the muscle fibers. In fat tissue, the majority of the hemorrhages had a petechial appearance. More diffuse hemorrhages were found in loose connective tissue (Figure 2). The histological study of hemorrhages in different types of muscles showed that the morphological appearance of the blood extravasation is determined by the structure of the tissue as well as by the amount of blood leaving the circulation. Some hemorrhages were associated with hypercontracted and disrupted muscle fibers, indicating that they were caused by severe muscular strain. Many hemorrhages were found near venules or veins and were packed with erythrocytes, surrounded by intact adipocytes and connective tissue. Rupture was observed only in venous structures, such as postcapillary venules and small veins, not in arterial vessels. This strongly indicates that a local rise in venous blood pressure can cause rupture of venules and small veins. The force experienced during electrical stunning probably depends on the posture or restraining method of the slaughter animals. For instance, shackling involves hanging live birds upside down, whilst suspended by their feet. The restrained legs carry the body weight of the birds. Electrical water bath stunning of broilers has the most detrimental effect with respect to muscle hemorrhaging. A poor bleed out can significantly increase hemorrhage conditions in broilers. Electrical stunning with currents that induce cardiac arrest in the majority of the broilers is associated with a high incidence of red wing tips. This is explained by inadequate bleeding of the birds after cardiac arrest. The wings of killed instead of stunned birds hang low resulting in stagnation of blood in the wing

veins. The use of high frequency (500 and 1500 Hz) stunning currents resulted in a decrease in carcass downgrading and a marked reduction in the occurrence of breast muscle hemorrhages, which represent significant commercial benefits. In lambs subjected to head-to-back stunning, higher currents and longer-stunning durations increased the severity and incidence of speckle in the legs but not in the loin. The reason for this is that its electrode placement ensures a maximal tetanic effect over the whole musculature of the loin. There are effects on speckle in the leg due to stimulation through the nervous system. It is well known that ac currents between 50 and 100 Hz cause substantial injuries in salmon, but an older study indicates that dc currents although tending to improve the quality do not guarantee efficient stunning. The combined ac/dc supply used in the experiment was not only efficient for stunning but also did not provoke internal injuries such as spinal deformities or rupturing the aorta dorsalis in fish.

Practical Application Ruminants Sheep and calves are regularly stunned using head-only or head-to-back electrical methods. For head-only stunning, the current is either delivered via scissor-model stunning tongs with pointed steel electrodes placed on either side of the head or a pistol grip-like handpiece holding the electrodes. The head of animal may be wetted with a water jet in order to improve electrical conductivity between the head and stunning electrodes. The electrodes should be positioned on both sides of the head between the eye and ear such that they span the brain during head-only stunning. This type of stunning is termed ‘head-only’ stun that does not stop the heart. As the animal can potentially recover and the slaughterman cuts the throat before the animal recovers (i.e., effectively taking the life of the animal), this procedure is therefore consistent with halal slaughter. During head-to-back or body stunning, one electrode should be positioned on the head and the other one on the withers or loin back such that the two electrodes span the brain and heart. The duration of insensibility associated with a head-only electrical stunning in sheep is 34−45 s, and recovery can be prevented by rapid exsanguination. Head-to-body stunning can cause cardiac arrest and as the spinal cord is also in the pathway, it additionally reduces the animal's reflexes with significant movement reduction, making it a good option when halal slaughter is not required. In cattle, the head of the animal is usually restrained by two parallel bars, which also serve as stunning electrodes. After head-only stunning for 4 s with 1.5−2.5 A, the animal is rolled out of the stun box on to a conveyor and bled out by a throat cut within 10 s from the end of stun. While bleeding, a low voltage pulsed direct current is applied from nose to rump of the animal for a minimum of 30 s (80 V, 15 Hz). This results in a still carcass, enhancing worker safety and producing a degree of electrical stimulation that protects meat tenderness. Alternatively, head-only electrical stunning in cattle is swiftly followed by the application of a second current cycle from the

Stunning | Electrical Stunning

Figure 3 Correct placement of the stunning tongs on the head.

muzzle to brisket of the animal to induce cardiac ventricular fibrillation. A double-rail conveyor restrainer for cattle or sheep in an upright position with the legs straddling and the body supported by the belly has been developed. The animals experienced less stress in this system. It is recommended to use a double-rail restrainer and stun the animal in an upright position.

Pigs Most slaughter pigs are stunned electrically. The current is delivered via scissor-type stunning tongs positioned on both sides of the head between the eye and ear such that the electrodes span the brain for head-only electrical stunning (Figure 3). During head-to-back or -body stunning, one electrode is on the head and the other on withers, loin back, foreor hindleg such that the current flows through the head as well as heart. In the case of the head-body position, a cardiac arrest may occur. It is considered that the pig skin has a high resistivity and penetrating this layer would improve current flow. Several automatic electric stunning methods are available. One device consists of two V-type restrainers running at a different speed in order to separate the successive animals. At the end of the second restrainer, each pig touches the electrodes and the current is passed. In another method, pigs make automatic contact on the head with two electrodes at the end of one V-type restrainer. After stunning, the animals are turned out and fall onto a table. A third method is automatic electric stunning at a band restrainer. At the end of the restrainer, the nose of the pigs interrupts a beam of light that initiates the electrodes. The electrodes are positioned between the eye and ear. After 1 s of stunning a heart electrode is positioned behind the left shoulder for 1.5 s. As a result of the body current, the animals do not show muscle contractions.

Poultry Water-bath electrical stunning is commonly used under commercial conditions where large throughput rates are required. In this system, birds are hung upside down on a moving, metal-shackle line (shackling), and passed through an electrified water bath, such that the current flows through the whole

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body toward the shackle, which serves as the earth. In waterbath systems, the electrical current is applied to the whole body, and the minimum current necessary to induce unconsciousness and insensibility depends upon the waveform and frequency of current used. However, the minimum currents recommended for broilers increase quality defects (hemorrhages, broken bones) of carcasses and meat. An alternative to whole-body electrical stunning is head-only stunning, where the stunning current only passes through the head of the birds. Head-only electrical stunning has been evaluated using a cone-shaped restrainer in which the broilers were suspended by their feet. Broilers may be insensible and unconscious after head-only electrical stunning with pinelectrodes using a current of 190±30 mA for 0.5 s. For practical implementation, a set current of 250 mA is recommended to overcome individual differences in resistance. To prevent recovery the stun should be followed by an immediate neck cut.

Fishes Electronarcosis is used to immobilize fish for routine laboratory or farming practices. In general, 50−70 V depending on the length of the fish is used. Assessment of narcosis in fish by several researchers has been based on behavioral observations and clinical signs of recovery. It is assumed that narcosis lasts until the onset of opercular movement, the first response to a stimulus, and the commencement of swimming. Electricity has been used in various studies to stun farmed fish species. It is known that the specifications for electrical stunning are not only dependent on fish species but also are partly determined by waveform, field strength of the current applied, and water conductivity. There are two approaches of electrical stunning applicable for use in practice. The fish species can be either stunned in water or after withdrawal from the water. Stunning in water involves exposing the fish to an electrical current administered via two plate electrodes in a tank. For stunning after dewatering, the fish is placed in a device that consists of rows of steel flaps as positive electrodes and conveyer belts or steel plates as negative electrodes. In principle, electrical stunning in water reduces stress in the fish, whereas applying stunning after dewatering the fish may result in exposing the fish to air longer.

Other Species Ostriches are stunned by electrical means (head-only and 80/ 90 V) or by captive bolt and suspended by both legs by chains hanging from the ends of an upturned horizontal bar. The animal is then lifted and bled. Based on clinical parameters, it was recommended that the current to stun ostriches is 500 mA. Preslaughter stunning of rabbits is now usually carried out by the preferred method of employing electrical currents. A wall mounted V-shaped metal electrode, with serrated edges for optimum contact, can be used as the stunning electrode. The head of the rabbit is placed into the V of the electrodes, which makes firm contact with the back of the eyes and the base of the ears to span the brain. Electrical stunning can be achieved using currents in excess of 140 mA.

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See also: Exsanguination. Preslaughter Handling: Preslaughter Handling. Religious Slaughter. Slaughter, Ethics, and the Law. Slaughter-Line Operation: Sheep and Goats. Stunning: Slaughter: Immobilization

Further Reading Anil, M.H., McKinstry, J.L., 1992. The effectiveness of high frequency electrical stunning in pigs. Meat Science 31, 481–491. Barham, W.T., Schoonbee, H.J., Visser, J.G.J., 1987. The use of electronarcosis as anaesthetic in the cichlid, Oreochromis mosambicus (Peters). I. General experimental procedures and the role of fish length on the narcotizing effects of electric currents. Onderstepoort Journal Veterinary Research 54, 617–622. Blackmore, D.K., Delaney, M.W., 1988. Slaughter of Stock. Palmerston North, New Zealand: Veterinary Continuing Education, Massey University Publ. No. 118. Channon, H.A., Payne, A.M., Warner, R.D., 2003. Effect of stun duration and current level applied during head to back and head only electrical stunning of pigs on pork quality compared with pigs stunned with CO2. Meat Science 65, 1325–1333. Cook, C.J., Maasland, S.A., Devine, C.E., Gilbert, K.V., Blackmore, D.K., 1996. Changes in the release of amino acid neurotransmitters in the brains of calves and sheep after head-only electrical stunning and throatcutting. Research in Veterinary Science 60, 225–261.

Devine, C.E., Gibert, K.V., Ellery, S., 1982. Electrical stunning of lambs: The effect of stunning parameters and drugs affecting blood flow and behaviour on petechial haemorrhage incidence. Meat Science 9, 247–256. Gregory, N.G., 2005. Recent concerns about stunning and slaughter. Meat Science 70, 481–491. Hindle, V., Lambooij, E., Reimert, H.G.M., Workel, L.D., Gerritzen, M.A., 2010. Animal welfare concerns during the use of the water bath for stunning broilers, hens, and ducks. Poultry Science 89, 401–412. Kranen, R.W., Lambooy, E., Veerkamp, C.H., Van Kuppevelt, T.H., Veerkamp, J.H., 2000. Histological characterization of hemorrhages in muscles of broiler chickens. Poultry Science 79, 110–116. Lambooij, E., Anil, H., Butler, S.R., et al., 2011. Transcranial magnetic stunning of broilers: A preliminary trial to induce unconsciousness. Animal Welfare 20, 407–412. Lambooij, E., Grimsbø, E., Van de Vis, J.W., et al., 2010. Percussion and electrical stunning of Atlantic salmon (Salmo salar) after dewatering and subsequent effect on brain and heart activities. Aquaculture 300, 107–112. Papinaho, P.A., Fletcher, D.L., 1996. The effects of stunning amperage and deboning time on early rigor development and breast meat quality of broilers. Poultry Science 75, 672–676. Raj, A.B.M., 2006. Recents developments in stunning and slaughter of poultry. World's Poultry Science Journal 62, 467–484. Sparrey, J.M., Wotton, S.B., 1997. The design of pig stunning tong electrodes − A review. Meat Science 47, 125–133.

Mechanical Stunning B Algers and S Atkinson, University of Agricultural Sciences, Skara, Sweden r 2014 Elsevier Ltd. All rights reserved. This article is a revision of the previous edition article by FD Shaw, volume 3, pp 1336–1342, © 2004 Elsevier Ltd.

Glossary Corneal reflex Blinking (fast or slow) in response to stimulus of the cornea. Eye movements A correctly stunned animals will show fixed eyes: They are wide open and glassy, and no nystagmus (spontaneous rapid side to side (twitching)

Introduction The Physiology of Mechanical Stunning The main method for stunning cattle is the penetrative captive bolt. It is intended to produce immediate unconsciousness and insensibility that lasts until death occurs from exsanguination. Well-serviced and -maintained weapons should consistently achieve proper stunning in cattle. The stun effectiveness (stun quality) can be influenced by variations in cattle breed, size and maturity, as well as differences in mechanical properties of commercially available guns. There are two types of captive bolt guns: penetrating and nonpenetrating. In penetrating captive bolt guns, a metal rod is propelled from the muzzle of the gun by the discharge of a blank cartridge inserted in a chamber behind the proximal end of the bolt. In nonpenetrating captive bolt guns, a mushroom head-shaped bolt is propelled from the muzzle of the gun by the discharge of a blank cartridge inserted in a chamber behind the proximal end of the bolt. The use of the penetrating captive bolt is also referred to as concussion stunning and the nonpenetrating bolt as percussion stunning. The impact of the bolts on the head of an animal causes concussion of the brain and rupture of brain blood vessels, leading to unconsciousness. The bolt velocity varies according to the gun powder content within a selected cartridge, which is usually color coded by the manufacturer. When a penetrating captive bolt gun is fired on the head, the sharp-rimmed bolt enters the skull and brain and then recoils automatically back into the barrel of the gun. The depth of penetration into the skull varies according to the length of the bolt and the power of the weapon. The captive bolt should create a large, deep, penetrating, and well-defined hemorrhagic track which traverses almost the full thickness of the brain. It should cause severe damage to the cerebellum, brainstem, and caudal aspect of the cerebral hemispheres with marked subarachnoid and intraventricular hemorrhages, especially adjacent to the entry wound and around the base of the brain. The rupture of arteries entering the brain ensures a lasting unconsciousness and insensibility during shackling, hoisting, and sticking (exsanguination or bleeding) procedures until death of the animal (Figure 1).

Encyclopedia of Meat Sciences, Volume 3

movements of the eyeballs). They will also not show eyeball rotation, in which the eyeball rolls so mostly pink sclera can be seen and little or no iris. Spontaneous blinking Animal opens/closes eyelid on its own (fast or slow) without a stimulation.

The bolt velocity and angle of firing determine the effectiveness of stunning, and the kinetic energy impacted on the skull travels to the basal area of the brain. Exsanguination should be carried out without undue delay following captive bolt stunning. In cattle, exsanguination is normally performed by inserting a knife at the base of the neck pointing toward the chest and severing the brachiocephalic trunk and anterior vena cava. The effects of different bolt velocities at stunning on brain function may be investigated by looking at visual evoked responses (VERs) as an index of brain damage. VERs, induced by flashing a strobe light in front of the animal, are recorded along with the spontaneous brain activity by way of electroencephalograms (EEGs) recorded using electrodes attached to the head or electrocorticograms (ECoGs) recorded using electrodes implanted (under anesthesia) on the surface of the

Figure 1 Typical brain hemorrhage in a well-stunned animal (notice heavy bleeding track down the central part of the brain).

doi:10.1016/B978-0-12-384731-7.00153-7

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brain area responsible for normal vision (known as visual cortex). The electrical activity evoked by the flashing light indicates the brain's ability to respond to external stimulus. VERs are present in conscious as well as unconscious animals, but their loss indicates an insult to the brain sufficient to cause failure of a primary sensory pathway, and are therefore used as an indicator of profound brain failure, and hence unconsciousness and insensibility. The capability of penetrating captive bolt guns to obliterate VERs depends on bolt velocity and the shot accuracy. In an experiment conducted by Daly in 1987 on the effect of bolt velocity and diameter on abolition or retention of VERs, it was found that visual-evoked responses are abolished or significantly reduced in amplitude as energy transfer increases and that energy transfer increases with bolt diameter (Table 1). The application of the shot should be at a point derived by the two lines between the ear base and the opposite eye (A, Figure 2). Bolt velocity is reduced if (a) incorrect cartridges for the species and size of animal are used, (b) the cartridges are damp

(kept in humid environments), and (c) the gun is dirty or has worn out or damaged parts. The impact of a captive bolt can also be seriously hindered if the operator applies the gun at an incorrect angle or too far away from the animal's forehead. In principle, the gun should be placed flat on the animal's forehead at a 90 degree angle to achieve the maximum impact. If animals are moving within the stun box, obtaining the correct shooting angle, location, and closeness on the forehead can be difficult. This can be especially a problem when shooting relatively small animals such as calves in a large stun box designed for adult cattle. It is worth noting that sheep and cattle stunned in the poll position are less likely to lose VERs than those shot frontally. Also, increasing bolt velocity when stunning cattle increases the likelihood of them losing VERs, but even very high velocities are not invariably successful in this species. The impact of the bolt with the cranium is the principal determinant of effective stunning rather than the penetration of the bolt into the brain tissues. Furthermore, the tissue damage produced by the passage of the bolt through the brain tissue does not necessarily contribute to loss of VERs.

Table 1 Effect of bolt speed and bolt diameter of a captive bolt gun on energy transfer (joules), to the head of the animal and the prevalence of visual-evoked responses in the cortex of the brain

Assessment of Stun Quality

Bolt speed (m sec1)

The following criteria may be used to determine an effective stun:

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55

Bolt diameter (mm)

Energy transfer

Evoked responses

Energy transfer

Evoked responses

12 14 16

97 þ 17 125 þ 18 158 þ 20

3/6 2/8 1/7

124 þ 25 139 þ 25 186 þ 30

1/8 1/8 0/7

Source: Reproduced from Bouton, P.E., Fisher, A.L., Harris, P.V., Baxter, R.I., 1973. A comparison of the effects of some post-slaughter treatments on the tenderness of beef. Journal of Food Technology 8, 39−49.

B E

A D

Figure 2 Accurate shot application.

C

1. Immediate collapse of the animal 2. Brief tetanic spasms that might be followed by uncoordinated hind limb movements 3. Immediate and sustained cessation of rhythmic respiration 4. Absence of coordinated attempts to rise 5. Absence of vocalization 6. Glazed “glassy” appearance of the eyes 7. Absence of eye movements and reflexes Ineffective stunning is considered to occur if animals show any of the following symptoms: nystagmus, eyeball rotation, vocalization, rhythmic breathing, righting reflex, spontaneous blinking, or corneal reflex. Other symptoms may be failure to collapse properly, excessive ear or tail tonus, or excessive kicking. Animals can show signs outside of these criteria due to neural reactivity occurring from various levels of physical injury to different parts of the brain. Despite the instantaneous brain trauma caused by penetrating captive bolt stunning, the physical manifestation of its effect can occur in stages. For example, kicking movements can occur at various times after the stun. The actual sticking process can also cause a further bout of kicking or front leg and head movements that are not necessarily associated with ineffective stunning. To be sure that there is no risk of recovery, eye reflexes must be absent. Bulls tend to display eye rotations and nystagmus more often than other cattle classes, and if seen in isolation, these symptoms represent a risk of recovery rather than a symptom of sensibility. Eye rotation can also sometimes occur for a short period immediately after stunning and persist for up to 15 s, then the eyeball centers in the socket and the glazed appearance of proper stunning occurs as the animal falls into a state of coma or death ensues. However, to prevent any risk of

Stunning | Mechanical Stunning recovery, and especially if seen with other symptoms, the animal should be restunned when these symptoms appear and remain for more than 15 s. It is important when assessing stun quality that animals are inspected during the whole stun to stick period and during bleeding. A judgment should be based on the absence or presence of certain symptoms, and further inspection is warranted when symptoms outside of the deep stun criteria appear. For example, symptoms that indicate that the animal should be checked more closely for further signs include stiff ears usually held upright, gasping, stiffness in the jaw, absence of a protruding tongue while on the shackle or during sticking procedures, and excessive head or paddling movements that hinder the sticking process. An immobile tongue hanging out of the mouth is a valuable sign of an effective stun but is not a requirement for the diagnosis of effective stunning. If at any time animals show a positive corneal reflex or spontaneous blinking, the animal must be restunned immediately. If an appropriate captive bolt gun is fired with the correct cartridge and positioned in the appropriate angle, captive bolt stunning should achieve a close to 100% success rate. The risk for inadequate stunning can be reduced in larger cattle (i.e., bulls) by using well-serviced, commercially available, pneumatically operated bolt guns because of the higher power and bolt velocity compared to conventional captive bolt guns. Brain damages seen in pneumatically operated bolt guns have been shown to be larger, with more severe hemorrhaging at the base of the brain, suggesting that the brain is shaken more vigorously within the cranium due to the impact of shooting cattle with these guns, contributing to higher stun quality. Problems with animal welfare can be minimized by designing handling facilities in abattoirs that consider natural speciesspecific behavioral principles. The effectiveness of the stun also depends on the skill of the abattoir staff, who should be adequately trained and certified. It is important to assess each situation separately when deciding whether standards at a given abattoir are satisfactory from an animal welfare perspective. However, by implementing quality assurance schemes in abattoirs including external stun quality auditing by appropriately trained personnel, animal welfare can be safeguarded.

Practical Considerations Bulls tend to be more difficult to stun than other cattle classes due to their thicker skull and greater hair mass on the forehead, which reduce bolt velocity as well as the transfer of energy to the brain. For consistent, effective stunning of bulls, it is therefore pertinent to use well-maintained, clean, and high-performance captive bolt guns. Bolt velocity (and stun effectiveness) can also be reduced in the event any part of the gun is damaged, worn, or dirty. In high-throughput abattoirs, the repeated use of the same captive bolt gun may cause overheating, reducing its efficacy. Changing guns frequently, e.g., after every 20 animals or so, may prevent this problem. It is also advisable to use a separate gun appropriate for the size of cattle, e.g., cows, steers and smaller cattle, and bulls. The use of a well-maintained pneumatically operated captive bolt gun and properly designed, constructed, and maintained neck

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Figure 3 Pneumatic stunner.

Figure 4 A bull in a stun box with a neck restraint ready for stunning.

restraints help to achieve effective stunning in bulls (Figures 3 and 4). Free bullets can also be used in field conditions (e.g., during disease outbreaks) fired using either a conventional or modified rifle, with a high velocity bullet (9 mm) (Figure 5). In many abattoirs, however, due to the associated risk to human safety from possible ricochet, captive bolt guns are more often used. Stun quality not only impacts on animal welfare but also greatly influences meat quality. In small and older abattoirs, cattle are manually driven by a stock person from single line laneways into a final enclosed pen or ‘stun box.’ The stunning process involves a shooter leaning over the animal from an elevated platform and

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Figure 5 Two modified weapons used for stunning bulls and cows. The original weapon is shown above and the two weapons below have been modified to activate the firing of the bullet only when the trigger is pressed and the rod under the muzzle is pushed in when placed on the animal′s forehead.

Figure 7 A restraint device for pneumatic stunning of cattle using both neck restraints and a chin-lift.

restraints and chin lifts, are operated slowly and smoothly to reduce fear reactions in the cattle. Operating these devices too quickly can startle the animals and set them into a panic response at the time of shooting.

Abattoir Audits The guns and their maintenance records should be inspected and the type of cartridge should be appropriate for the type of cattle. A decent sample size needs to be inspected during stunning, and this probably requires spending a day making observations during the slaughter process. The system for loading the stun box, the restraint devices used, and observations of the animals' reactions in the stun box should be noted. If many animals (420%) are showing severe retreat or struggle and escape attempts during loading the stun box and at stunning, the facilities and the staff should be reviewed to identify the problem areas. A sample of the stun to stick times should also be noted (at least 10%). Prolonged sticking times can increase the recovery risk. Figure 6 A typical type of stunning system with captive bolt.

shooting the unrestrained animal in the forehead with a cartridge-fired captive bolt gun (Figure 6). Recently, new automated designs have been developed to improve cattle handling and stunning. Cattle are loaded into the stun box with the help of a hydraulically operated moving gate, which pushes the animal forward into the stun box. The stun box is partly open in front, reducing the perception by the animal of ‘dead end,’ and facilitates voluntary forward movement of the animal. The animal can place its head through an opening where it is restrained by hydraulically closing metal bars on the side of the neck. A shelf can also be used to lift the head up by pushing under the animals chin (chin-lift) (Figure 7). If cattle are stressed and frightened, they can attempt to escape the stun box or move the head out of reach of the operator making it difficult for the shooter to position the gun in the optimal area to achieve an appropriate stun. The purpose of restraint devices is therefore to hold the animal still and the chin-lift presents the forehead to make shooting easier and more accurate. It is important that push gates, neck

See also: Automation in the Meat Industry: Slaughter Line Operation. Equipment Cleaning. Exsanguination. Meat, Animal, Poultry and Fish Production and Management: Red Meat Animals. Microbiological Safety of Meat: Prions. Preslaughter Handling: Preslaughter Handling; Welfare of Animals. Quality Management: Abattoirs and Processing Plants. Religious Slaughter. Slaughter, Ethics, and the Law. Slaughter-Line Operation: Cattle; Pigs. Species of Meat Animals: Cattle; Sheep and Goats; Pigs. Stunning and Killing of Farmed Fish: How to put It into Practice?. Stunning: Slaughter: Immobilization

Further Reading Algers, B., Anil, H., Blokhuis, H., et al., 2009. Project to develop Animal Welfare Risk Assessment Guidelines on Stunning and Killing. Project developed on the proposal CFP/EFSA/AHAW/2007/01. Available at: http://www.efsa.europa.eu/ EFSA/efsa_locale-1178620753812_1211902958022.htm (accessed 22.10.09).

Stunning | Mechanical Stunning Daly, C.C., 1987. Recent developments in captive bolt stunning. Humane slaughter of animals for food. In: Ewebank, R. (Ed.), Proceedings of a Symposium Organised by the Universities Federation for Animal Welfare. Potters Bar, England: Federation for Animal Welfare, pp. 15–20. EFSA, 2004. Welfare aspects of the main systems of stunning and killing the main commercial species of animals. EFSA Journal 45, 1–29.

Relevant Websites http://www.grandin.com/humane/restrain.slaughter.html Dr. Temple Grandin's Web Page. http://www.hsa.org.uk/ Humane Slaughter Association.

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Slaughter: Immobilization M Appelt, Merivale Road, Ottawa, Ontario, Canada A Allen and D Will, Canadian Food Inspection Agency, Saskatoon, SK, Canada r 2014 Elsevier Ltd. All rights reserved. This article is a revision of the previous edition article by N Gregory, volume 3, pp 1353–1354, © 2004 Elsevier Ltd.

Glossary Avoidable pain and suffering Any additional pain and/or suffering of a food animal caused by how the animal is handled, restrained, slaughtered, or otherwise manipulated. Head gate A mechanical restraining device placed in the path of an animal, commonly used for bovine animals, that, when closed, provides a narrow opening large enough to contain the neck of the animal, but too small for either the head or shoulders of the animal to pass through.

Humane slaughter involves methods that meet the dual objective of minimizing the risk of injury to the slaughter person and not inflicting avoidable pain and suffering onto the animal – critical for avoiding ethical (animal welfare) and meat quality problems. Restricting an animal′s movement such that the desired method of slaughter can be reliably employed requires much more than only the physical restraint. It is important to understand that the experience an animal had during an earlier part of the process, between being on a farm and being delivered to slaughter, which will affect later stages of the process. At the time of slaughter, animals find themselves in unfamiliar environments, experiencing loud noises, strange odors, sometimes poorly designed facilities, are separated from their herd, and forced to interact with strangers – both animal and human. Most of our food animals are aware of their surroundings and are capable of directed movement to defend themselves, attack a threat, or get away from frightening situations. The desired outcome of a functional and humane slaughter setup is restrained, nonstressed animals that are calmly and reliably slaughtered on a consistent basis. The animals′ preslaughter and slaughter experience each play significant roles in achieving the desired outcome of safe and humane slaughter. It is imperative that the individuals involved have an understanding of animal behavior, handle animals appropriately and employ transport, preslaughter and slaughter facilities and equipment that are appropriate for the species, sex, age and number of animals being slaughtered. The more rigid a method of restraint, the more risk it generally poses for the welfare of the animal and the more important it becomes to apply the restraint correctly and keep the time the animal has to cope with the restraint to a minimum. The type and duration of preslaughter and slaughter handling and restraint vary greatly, depending on the economic circumstances, the part of the world in which it occurs, local customs and knowledge base, the species, size, and number of animals involved and the type of market that the end product is sold to and consumed in.

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Immobilization Implicates measures that interfere with the animal′s motor control, such as electric depolarization of the nervous system, to prevent directed movement, flight or attack. Religious or ritual slaughter Slaughter of a food animal while observing religious rites, traditions, or requirements. Common examples are Halal and Kosher slaughter. Restraint Restricting the space in which the animal can move about, usually by erecting physical barriers, such as a stun box, a cattle head gate, ropes, or manual force.

Western World ‘Immobilization’ is distinct from ‘restraint.’ Immobilization implicates measures that interfere with the animal′s motor control, whereas ‘restraint’ refers to restricting the space in which the animal can move about. Immobilization before slaughter is generally not considered necessary where preslaughter stunning methods are used and not acceptable in the western world. Rather, the ability of the animal to move is greatly restricted by confining the animal in a small enclosure (e.g., ‘knock box,’ ‘stun box’) for the brief period of time it takes to stun the animal and/or initiate the bleeding process. A conveyor belt may be used that supports the animals′ body but leaves the legs unsupported. Design features of the belt prevent struggling or escape. In bovine animals and pigs, such conveyor belt restrainers have a calming effect on the animals. The automated system presents an animal to the stunner at easily controllable intervals. When a bovine animal moves to the slaughter area under its own power, a head gate that, when closed, creates a narrowing of the space to both sides of the animal′s neck that, without applying painful pressure to the neck, is too narrow for the head to be pulled back or for the shoulders to push forward is most commonly used. Some forms of religious or ritual slaughter require even tighter restraint or a specific presentation of the animal. Examples are a head restraint that securely holds the head and extends the neck, or placing the animal into a rotating drum fixating the entire animal and intended to roll the animal on its back before the neck vessels being cut with a knife. For small ruminants, manual restraint during ritual slaughter is often sufficient. Poultry are unable to see in low levels of light or areas that are lit with blue light. This can be used to ensure that they remain calm during slaughter, as well as employing handling practices that avoid sudden movements and loud noises, similar to what is recommended for other animal species. When poultry are shackled (hung upside down on a conveyor in brackets that grasp the birds′ legs) to restrain and

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Stunning | Slaughter: Immobilization transport them through the process of slaughter, the moving conveyor line brings the birds′ breasts into contact with and moves them along a smooth breast bar to soothe or pacify the birds. This helps to ensure they remain calm as they approach and enter the automatic stunner and avoids wing flapping. In gas stunning, the birds sometimes find immersion into the gas pit noxious and stressful. This is especially true if the gas concentration gradient is too steep or the descent into the gas pit is too rapid. Calm and relaxed birds that have been handled well before their entry into the gas stunning device are less likely to struggle to escape. Some gas stunning poultry plants attempt to restrain stressed birds and prevent them from escaping by placing a physical barrier over the crate as it descends into the pit. In countries such as Australia, where night hunting of game animals is legal and common practice, bright spotlights trained onto the animals are used to temporarily immobilize animals while they are being shot with a firearm.

Fish Crustaceans, such as lobsters, are restrained with an elastic band placed around their claws, minimizing the harm that they can do to each other and the people that remove them from the lobster tank and submerge them in a boiling pot of water (slaughter) for consumption.

Emerging Economies In much of the world, slaughter, often of a single animal, provides for the family meal, a religious event or the local market. Slaughter may be carried out at home or at the farm. This is especially true for larger animals. Slaughter sometimes occurs at the local market only a short time before the meat being offered for purchase. In other circumstances – especially those involving fish and poultry – slaughter and evisceration may be carried out while the customer waits. Immobilization and restraint in emerging economies are often different from methods seen in the western world. Some of these, often traditional, methods are not acceptable when assessed toward current animal welfare criteria and their inclusion in this article does not constitute an endorsement of their use. Small ruminants, pigs and birds are held to the ground and their legs are then tied together so that they remain restrained up to and during slaughter. Standing animals are sometimes tied (tethered) together in groups pending sale or slaughter. There is usually a rope attached to a post or building. However, much of the restriction to movement is supplied by the other animals in the group. A method of restraining small ruminants is to have a person stand over the animal with their legs straddling the animal. The person′s legs are pressed firmly against the shoulder and rib cage on each side of the animal′s body. One hand (usually the left) is used to lift the animal′s head and pull it firmly against the body of the person while the right hand holding a knife is used to cut the animal′s throat.

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A small ruminant may also be on its back and held to the ground by several helpers that also stretch the neck, allowing the slaughter person access to the neck with a knife. Tying the small ruminant′s head to a fixed object (e.g., pole) or having a helper hold the head while stretching the hind legs firmly allows rapid decapitation with a sharp saber or cutlass. Confinement of animals up to the size of a pig in very small cages (metal, wooden, wicker, cardboard) is used during transport and sometimes even slaughter. For example, pigs may remain immobilized in a small form-fitting, basket-like cage for transport to the slaughter facility, while awaiting slaughter and may be bled out inside this cage by an operator using a knife on a long handle. Akin to low levels of lighting used calm birds during catching, preslaughter handling and slaughter, in some parts of the world a fabric bag or hood is sometimes placed over the head and eyes of animals so that they cannot see. These animals remain quite calm, even if there are high levels of activity and noise around them. Bags are sometimes used to hold and restrain poultry for transport and while they await slaughter. When this method of restraint is used, chickens are enclosed entirely in the bag. Larger birds, such as waterfowl, are often restrained with their body enclosed by the bag and their head and neck protruding. In some places, poultry are picked up by their legs (restraint) and their breasts lie against a block of wood until the birds become quiet and do not move (similar to ‘breast bars’ in western-style poultry slaughter). Then the birds are decapitated with an axe. The birds are held (restrained) by their feet until the bleeding and involuntary movement have stopped. A practice of immobilization of larger animals involving severing the spinal cord between the skull and the neck with a sharp, pointed knife (‘puntilla’) inserted into the foramen magnum is in use in some places. As soon as the knife severs the spinal cord, the animal collapses and can no longer move. The animal remains conscious throughout the bleeding process, until death through blood loss occurs, making this practice inhumane. Immobilization of large animals by severing tendons on the extremities is used in some countries. The practice leads to the collapse of the animal and makes it impossible for the animal to move its extremities. Immobilizing animals by flexing the joints of the extremities and tying them in this position is used for smaller species. Fish are held in tanks at markets pending slaughter. Fish placed in smaller containers are easier to grasp, especially if the water is warm and low in oxygen. Some individuals use their hands; others use small nets to catch the fish. The fish are held and immobilized by one hand while they are rendered (semi) unconscious with a blow to their head and eviscerated with the other hand.

Postslaughter Considerations The slaughter process includes the transition from a live, conscious animal to a dead carcass. Inevitably, there is an intermediate state, where the animal is no longer aware of its

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surroundings, but many organ systems are still functional. Voluntary, directed movement is replaced by involuntary kicking or paddling of extremities or flexing of the back. While this type of uncoordinated movement is a normal observation on a dying animal, it creates a hazard for workers, may slow the processing speed and can negatively affect meat quality. Immobilization of an irreversibly unconscious animal is acceptable and no animal welfare concerns exist at this point. Where penetrating stunning devices are used, mechanical disruption of the brain stem and spinal cord (‘pithing’) is achieved by inserting a metal or plastic rod through the hole left by the stunning device and advancing it toward the foramen magnum. Vigorous manipulation of the rod destroys vital brain stem and spinal cord structures and will successfully prevent convulsions or kicking. The penetrating stunning device and the pithing rod must be matched in order to avoid a hole too small for the pithing rod, making enlargement of the hole necessary. There are downsides of the procedure associated with the potential for introducing pathogens into the carcass by means of a contaminated rod or brushing bacteria off the forehead onto the rod or into the skull cavity or causing proteins implicated in prion diseases, such as bovine spongiform encephalopathy (BSE), to cross from nervous tissue into the bloodstream resulting from the mechanical damage to brain tissue and blood vessels. Dissemination of pathogens throughout the carcass is possible at this stage, because the animal has not yet bled out and some blood circulation still occurs. These concerns led to pithing no longer being accepted practice in many countries. Some countries may allow pithing after the animal has been bled. The use of electric current to immobilize animal carcasses is of increasing interest in slaughter practice, because it appears to avoid most of the pitfalls associated with mechanical methods of immobilization. Electrical immobilization (EI) is the application of electric current to the carcass to temporarily disrupt the nervous system. In general the peak voltage is usually relatively low (80 V) with a pulsed waveform approximately 15 pulses per second and is not regarded as dangerous (higher frequencies have been used) and is widely used for cattle. The animals are not only immobilized while the current is applied (e.g., from head to legs), and workers are protected from movement, but the lack of movement continues after the current is switched off. There is an additional advantage of using these voltage waveforms in that immobilization effectively becomes low voltage electrical stimulation if the duration is long enough. Nerve deactivation (ND) begins before carcass dressing will permanently disable nerve function and eliminates risk of injury to workers. If the voltage is higher than for EI, it can be applied for a shorter duration for a lasting effect. In the case of cattle that have been restrained and electrically stunned, they are already in an area where issues of electrical safety do not arise. Electrical back stiffening (EBS) is used at the hide pulling stage to contract the carcass back muscles while the hide is being removed. This reduces the incidence of spinal fracture.

Electricity from the power grid must be modulated and transformed in order to have the desired effect. Technical applications exist that tailor the current to suit the characteristics of the particular carcass being dressed at the time, taking into account parameters such as carcass electrical response, carcass biochemical parameters, muscle glycogen levels, type of carcass, and carcass weight. The EI, activation and deactivation methods listed above can be used individually or combined, at different stations in the process flow.

See also: Preslaughter Handling: Preslaughter Handling. Religious Slaughter. Slaughter, Ethics, and the Law. Stunning: CO2 and Other Gases; Electrical Stunning; Mechanical Stunning

Further Reading Blokhuis, H., 2004. Welfare aspects of the main systems of stunning and killing the main commercial species of animals. EFSA Journal 45, 1–29. Chambers, P.G., Grandin, T., 2001. Guidelines for Humane Handling, Transport and Slaughter of Livestock. Food and Agriculture Organization of the United Nations. Bangkok, Thailand. Regional Office for Asia and the Pacific, RAP Publication. Gregory, N., 2006. Anatomical and physiological principles relevant to handling, stunning and killing red meat species. Proceedings of the International Training Workshop Welfare Standards Concerning the Stunning and Killing of Animals in Slaughterhouses or for Disease Control, 26−29 September 2006 Bristol. Available from: Humane Slaughter Association, The Old School, Brewhouse Hill, Wheathampstead, Hertfordshire, AL4 8AN, UK. Richards, I., 2006. Electrical treatment of carcasses, U.S. Patent Office, USPTO Full Text and Image Database, U.S. Patent 7,025,669. Available at: http://patft.uspto. gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=% 2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=7025669.PN.& OS=PN/7025669&RS=PN/7025669 (accessed 14.10.13). Thiermann, A., World Organisation for Animal Health, 2013. Slaughter of animals. In: Terrestrial Animal Health Code. Paris: OIE, (Chapter 7.5), pp. 1−20. Available at: http://www.oie.int/index.php?id=169&L=0&htmfile=chapitre_1.7.5.htm (accessed 14.10.13).

Relevant Websites http://www.inspection.gc.ca/english/anima/trans/transprace.shtml Canadian Food Inspection Agency − humane handling and slaughter. http://www.fao.org/DOCREP/003/X6909E/x6909e00.htm#Contents Food and Agricultural Organisation. http://www.hsa.org.uk/Humane%20Slaughter%20Information.htm Humane Slaughter Association − preslaughter handling. http://www.patentgenius.com/patent/7025669.html Patent on carcass immobilization. http://www.oie.int/index.php?id=169&L=0&htmfile=chapitre_1.7.5.htm Slaughter for human consumption. http://www.grandin.com Temple Grandin livestock handling.

STUNNING AND KILLING OF FARMED FISH: HOW TO PUT IT INTO PRACTICE?

H van de Vis and W Abbink, IMARES – Wageningen UR, Yerseke, The Netherlands B Lambooij and M Bracke, Livestock Research – Wageningen UR, Lelystad, The Netherlands r 2014 Elsevier Ltd. All rights reserved.

Glossary Electrical stunning The immediate induction of unconsciousness and insensibility in an animal or fish caused by the passage of an electrical current of sufficient strength through the brain. Electrocardiogram Recording of the electrical activity of the heart muscles by using electrodes implanted or applied to the skin. Electroencephalogram Recording of electrical activity of the brain, using implanted or surface electrodes. Generalized epileptiform insult A state of brain characterized by abnormal, excessive or hypersynchronous neuronal activity throughout the brain, generally considered to lead to unconsciousness and insensibility. Insensible Inability to perceive (and as a consequence respond to) stimuli. Slaughter The killing of animals, especially farmed ones, for the production of food.

Introduction World aquaculture production of food from finfish comprised 36 million tons in 2010 and is increasing yearly up to 7–10%. The authors estimate that this production volume boils down to 7–120 billion of farmed fish slaughtered in 2010 (with an average weight of 5–0.3 kg, respectively). Asia accounted for 92% of world aquaculture finfish production by volume in 2010, whereas for Europe this was 5.2%. Several types of aquaculture are used for the production of food fish: ponds, land-based intensive flow-through systems, cage farming and recirculation aquaculture systems. In Europe, the production of Atlantic salmon (Salmo salar), European sea bass (Dicentrarchus labrax), and gilt-head seabream (Sparus auratus) rely mainly on cage culture at sea. For rainbow trout (Oncorhynchus mykiss), the ongrowing stage is done in different systems across Europe (for instance ponds and flow-through systems). In Asia, dominant fish are freshwater species such as various carp species and tilapia subspecies. Asian farmers perform ongrowing of these species predominantly in ponds. Owing to increasing societal awareness, especially in Europe, Canada, Australia, and New Zealand, attention has been drawn to fish welfare in aquaculture, which is still growing. In view of the fact that mammals and birds should be spared of unnecessary

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Stunning The process that renders an animal unconscious and insensible without causing avoidable stress and discomfort prior to death for a sufficient period of time to allow killing. Stunning/killing The process that renders an animal unconscious and insensible without causing avoidable stress and discomfort that subsequently induces death. Unconsciousness A state of unawareness (loss of consciousness) in which the brain is unable to process sensory input (e.g., during (deep) sleep, anesthesia or due to temporary or permanent damage to brain function). Vestibulo-ocular reflex A reflex where eye movement occurs when a fish's body is moved/tilted along a longitudinal axis (also referred to as eye roll). The absence of this reflex is not an evidence of unconsciousness in fish.

stress and discomfort at slaughter, the question is raised whether this concern is also relevant for farmed fish. In humans, awareness of pain and fear apparently depends on proper functioning of specific regions of the cerebral cortex. Because fish lack a cerebral cortex, it might be argued that fish do not have a capacity to experience pain and fear (sentience). However, Braithwaite et al.'s recently reviewed studies showing that teleost fish species have the relevant functional areas in the telencephalon for cognition and emotion. The reported studies show that it is possible that teleost fish perceive pain and fear when they are not stunned before killing or slaughter. The number of fish species studied for behavioral and brain function with respect to cognition and emotion is, however, limited. Within the class of fish there is a diversity with respect to phylogeny, behaviors and habitats, consequently, a variability is found in brain structure and functions among fish. Hence, detailed studies on a wider range of fish species are needed to characterize further the taxonomic distribution of such capacities. Commercially used methods, such as chilling of live fish by asphyxiation on ice or ice water slurry or killing by decapitation without prior stunning, might cause considerable pain and distress in these animals. These killing methods have been developed not to minimize stress but to achieve product quality control, efficiency, and processor safety. Therefore,

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there is a need to develop methods for stunning or stunning/ killing of farmed fish and implement them under commercial conditions and control the methods in that setting. In this article, therefore, the focus is on: Assessment of stunning and killing or stunning/killing of fish in a laboratory setting to establish ideal conditions for stunning or stunning/killing of fish without causing avoidable stress and discomfort and how the stunned fish can be killed without recovery of consciousness. Assessment of product quality parameters is also of interest as stunning or stunning/ killing may affect its properties. A method such as percussion can be suitable for stunning/killing, whereas fish recover from an electrical stun. In implementation of assessed stunning and killing or stunning/killing in a commercial setting, methods that are suitable for assessment are limited; it is likely that only observation of behavior and physical measurements to assess the equipment installed can be used. Control of the process for stunning and killing or stunning/ killing in a commercial setting can be achieved by using an effective management system. In a commercial setting, an approach that is process-oriented and focused on prevention rather than inspection only is needed, i.e., a quality assurance system.

Slaughter of Farmed Fish Slaughter is the process for killing of animals intended for human consumption. The term slaughter is also used to depict killing of animals by bleeding. Most farm animals are killed by bleeding. In general, the following steps for slaughtering can be distinguished: 1. Transport from the rearing enclosure to the slaughterhouse or facility for slaughter at the farm. 2. Restraint (fixation of an animal for a proper application of a stunning method). 3. Stunning, i.e., rendering the animal unconscious and insensible so as to reduce avoidable stress and discomfort before killing. The application of a method like percussion can be suitable to achieve both stunning and killing; in this case, step 4 is not performed. 4. Killing of the stunned animals. Figure 1 gives an impression of the four steps used in the slaughter process of Atlantic salmon, i.e., lairage, pumping, stunning, and killing. The percussive stunner in Figure 1(d) is used, as this machine has the ability to bleed the electrically stunned salmon automatically. Before transportation of live, farmed fish from a farm to harvest facilities for slaughter at the farm, the following process is normally carried out: fasting (withholding feed), crowding to facilitate capture of fish for loading into a transport vehicle, unloading of the fish and releasing them (e.g., in holding pen/ tank for lairage) before commencing slaughter at the harvest facility or at the facilities for slaughter on the farm. The welfare of farmed fish could be at risk at each of these steps in the process. However, in this article the authors focus on the methods of stunning and killing of farmed fish. For assessment

of welfare aspects of stunning methods, the general provision in the European Union (EU) legislation for warm-blooded slaughter animals can be used as a general term of reference. The general term of reference is met when stunning induces immediate loss of consciousness and sensibility in fish, which lasts until death or, when an instantaneous induction is not possible, the animal should be rendered unconscious and insensible, without causing avoidable pain and distress.

Stunning and Killing For stunning and killing of farmed fish, a wide range of methods are used. Killing methods used at present for farmed fish include asphyxia by chilling on ice in air, live chilling in ice water slurry, exposure of live fish to a salt bath or ammonia, freezing, bleeding (exsanguination) by cutting blood vessels through the gills, and the transfer of fish to water saturated with carbon dioxide gas. Most of these methods do not induce unconsciousness and insensibility immediately, nor do they prevent avoidable stress and discomfort. Only a limited number of methods have been shown to be able to result in immediate loss of consciousness and sensibility. The authors demonstrated that percussive stunning (a blow to the head) of Atlantic salmon resulted in an immediate onset of irreversible stunning, as judged from electroencephalogram (EEG) and electrocardiogram (ECG) recordings. However, this stunning/killing method, when delivered using a pneumatically operated bolt, required such a high pressure driving the percussive bolt that carcass damage of Atlantic salmon occurred, under the conditions used. Electrical stunning can induce immediate loss of consciousness and sensibility in fish. However, reported data show that fish cannot be killed by the use of electricity, as the fibrillation of the heart is not permanent. This implies that electrical stunning should be followed by a killing method to avoid recovery of the stunned fish. Because stunning and killing are procedures that take some time, it is normally necessary to apply the electrical current not only at a certain voltage, but also for a certain duration of time, so as to allow subsequent killing before the fish have recovered. For example, Nile tilapia can be stunned using an electrical stun lasting for 5 s and the unconscious fish can be killed subsequently by chilling in ice water slurry. A problem of electrical stunning, especially when fish are immersed in water during stunning, is that carcass damage might occur, such as muscle hemorrhages or a broken vertebral column. Roth et al. found that this problem could be overcome by exposing fish to the electricity after draining the water, so called ‘dry stunning.’ In this method, the fish are exposed to an electrical current via a series of rows of positiveplate electrodes and a conveyor belt acting as the negative electrode. Evidence shows a positive effect on the quality with a very low incidence of injuries in Atlantic salmon. In Australia, Chili, Korea, and New Zealand, and some other countries outside of Europe, it is allowed to add the chemical compound Aqui-STM (with isoeugenol as the active ingredient) to the water in order to stun and kill fish. Using EEGs and ECGs isoeugenol can result in an effective and irrecoverable stun in cod. Isoeugenol is a food grade substance

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(a)

(b)

(c)

(d)

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Figure 1 (a) Stunning and killing of Atlantic salmon: lairage, (b) pumping of fish to the slaughter facilities, (c) electrical stunning after draining the water, and (d) killing the stunned fish by percussion and gill-cutting.

based on clove oil. Barriers to its use in the EU include the cost of overcoming the legislative requirements to introducing isoeugenol as anesthetic for food fish. In Norway, live chilling of Atlantic salmon with controlled addition of low to moderate levels carbon dioxide (65– 257 mg l1) and oxygen has been widely used to stun the fish. This method, however, has not yet been assessed with EEG and ECGs recordings.

How to Assess Stunning and Killing Welfare Aspects To establish whether the general term of reference is met after the application of a stunning method, the onset and duration of unconsciousness and insensibility in fish has to be assessed in a laboratory setting. Behavioral measures only are insufficient to assess the level of brain function of fish unequivocally. On the EEG, the electrical activity in the brain is monitored. In addition, nociceptive stimuli are administered to determine whether the stunned fish can be aroused, both on the EEG and

behaviorally. When the fish do not respond, this implies that the fish remain unconscious and insensible until death occurs. The electrical activity of the heart (as determined using ECG) should also be recorded to assess stunning methods. The ECG can be used to determine, for example, whether fibrillation occurs or when the heart rate changes. In case of fibrillation, the circulation of blood in the body is reduced, including the supply of oxygen to the brain. Changes in heart rate might occur in fish that are subjected to live chilling on ice in air or using ice water slurry, carbon dioxide gas or chemical stunning. When these changes are observed before loss of consciousness, they can be signs of stress in fish. Owing to the highly technical nature of recording the electrical activity in the brains and hearts of fish, conditions to achieve an effective stun in fish without causing avoidable stress and discomfort until death occurs need to be established in a laboratory. For an instantaneous electrical stun, sufficient current should be passed through the brains of animals to induce a general epileptiform insult (where all brain parts are stimulated). The epileptic process is characterized by rapid and extreme depolarization of the membrane potential, but there is

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heterogeneity of findings. It is generally assumed that animals are unconscious and insensible during a general epileptiform insult. Generalized epileptiform insults was observed in various fish species following electrical stunning. For percussive stunning, the patterns on the EEG, characteristic for an instantaneous stun, differ from those recorded in fish that are stunned using electricity. Percussive stunning of Atlantic salmon resulted in the appearance of theta and delta waves and spikes, which were followed by an isoelectric line. Exposure of cod to Aqui-STM resulted in a slow increase in theta and delta waves and a decrease in the alpha and beta waves, which is indicative for loss of consciousness and sensibility. For field observations (i.e., during slaughter on a commercial farm or in a harvest facility), registration of EEGs and ECGs might not be feasible. In this case, observation of behavior can be used. Spontaneous behavior (e.g., righting response and escape behavior), responses to stimuli, and physical reflexes (vestibulo-ocular reflex) can be used as preliminary behavioral observations to evaluate loss of consciousness and sensibility in fish. To scale the observations, a three-point scoring system can be used, where 0 designates no response, 1 refers to an attenuated or abnormal response or behavior, and 2 indicates a normal and clear response or behavior. Immediately after an effective electrical or percussive stun, rhythmic breathing as evidenced from the rhythmic gill movements should be absent, and the capacity of the fish to swim in a coordinated way lost. In an experiment with electrical stunning of Atlantic salmon followed by gill-cutting, we observed on the EEGs that one out of three fish recovered. The vestibulo-ocular reflex (eye roll) in the recovered fish was still absent. In properly stunned fish, the capacity to right themselves is also lost. When live chilling or gas stunning results in escape attempts, it is likely that the fish are conscious and stressed. Fish can be motionless for a number of reasons, such as paralysis, exhaustion, chilling, or tonic immobility (feigning death). In such cases, motionless fish might well be conscious. Caution is therefore needed when using behavior and physical reflexes to determine the effectiveness of stunning methods in practice. Therefore, the use of EEG recordings, including evoked responses on the EEG by administering nociceptive stimuli to the fish, are necessary for an unequivocal assessment of the level of brain function in fish to determine whether or not the fish are effectively stunned. Chemical stunning (i.e., the use of a gas and a combination of gases or a chemical such as Aqui-STM) or chilling of fish by exposing them to a drop in temperature do not result in an instantaneous stun. In such cases, the observation of behavior and the registration of EEGs and ECGs should be supplemented with stress-physiological measurements. Owing to their complexity, stress-physiological measurements might only be feasible in a laboratory setting. Analysis of plasma cortisol, glucose and lactate, as indicators for stress in fish, might not be sufficient when Nile tilapia (Oreochromis niloticus) are exposed to a noxious stimulus as exposure of a fish to ice or ice water may be noxious. These stress parameters did not allow discrimination between a tailfin clip as noxious stimulus and the handling stress. However, the following parameters indicated a strong differential response in the clipped Nile tilapia: (1) a remarkable

migration of chloride cells into the lamellar epithelium of the gills; the chloride cells in the gills are involved in the osmoregulatory performance of fish, (2) swimming activity of the Nile tilapia increased and the clipped fish spent more time in the light than in a dark region in the tank, and (3) the gill's mucus cells released their content. Regarding exposing a fish's to rapid temperature drop, it is important to note that fish's homeostasis might be fine-tuned to a particular temperature. To understand the possibilities of analyzing the stress response in fish exposed to live chilling on ice or in ice water slurry, some information on the time course of physiological stress response is presented. It is known that changes in cortisol, glucose, and lactate levels in the blood of fish normally occur within a time frame of minutes. Hence, it is possible that due to rapid chilling of fish, no changes in these blood parameters can be detected, due to a fast decrease in metabolism in fish caused by the temperature drop in fish. Therefore, caution is needed to interpret stress-physiological parameters such as cortisol, glucose and lactate when analyzing fish exposed to rapid drop in temperature.

Physical Measurements To assess whether equipment for stunning and killing of fish in practice meet the established criteria for stunning and killing or stunning/killing, physical measurements are needed. For electrical stunning, the strength of the electrical current (in water it is the height of the current density), its waveform, the applied voltage (in water it is the field strength) and duration of exposure of fish to the electricity need to be established, as well as the time interval between fish leaving the stunner and the application of a killing method. When percussion is applied, it should be measured whether the air pressure, which drives the bolt, is sufficiently high. For chemical stunning (gas and a combination of gases or in countries which allow AquiSTM for slaughter) the dosage and duration of exposure of the fish need to be assessed.

Product Quality The assessment of product quality is relevant for the industry, as stunning and stunning/killing of fish can affect product quality parameters. In addition, a reduction of stress during slaughter might delay the onset of rigor mortis (i.e., the stiffening of the body after death), which is relevant for prerigor filleting of, for example, Atlantic salmon. Analysis of product quality might not be feasible in a commercial setting and, therefore, these experiments should be performed in a laboratory. However, collection of stunned and killed fish in practice for analysis in a laboratory is doable. To assess the effects of stunning and killing on product quality, a range of indicators can be used: 1. Appearance of the fish and fillet, for example, residual blood, fillet gaping, and color. 2. Technological properties of fish and fillet, such as texture, water holding capacity, drip loss, and fillet shrinkage (in relation to prerigor processing).

Stunning and Killing of Farmed Fish: How to put It into Practice?

3. Freshness indicators: analysis of freshness, using K-value (calculated from adenosine triphosphate-degradation products). 4. Sensory properties and shelf-life; sensory traits of cooked fillets as texture, taste, flavor and odor, and microbial counts.

How to Control the Process of Stunning and Killing in Practice? Current ethical concerns about aquaculture, which are broader than welfare of fish alone (for instance ecological aspects of aquaculture), drive the preparation of certification schemes that may include consideration of fish welfare, as for instance in the Freedom Food concept for Atlantic salmon. Increasing calls from nongovernmental organizations and supermarkets in Europe also promote optimization of fish welfare using a certification scheme with appropriate standards. Furthermore, embedding in auditing procedures for accreditation is required to ensure that labeled products comply with the established standards for optimized fish welfare. Monitoring and auditing procedures, generally, do not focus on preventive measures and they might not control the entire process. To supplement existing procedures, a strategy is needed based on a thorough analysis of the conditions used during the whole process of stunning and killing, considering the specific requirements of a fish species. For this purpose, Quality Assurance appears to be a suitable approach, as it is process-oriented, efficient, focused on preventing hazards, and it involves establishing critical points/steps and standards for all steps in the production process. Previously, the authors developed a Quality Assurance system for safeguarding the welfare of fish at the fish farm – Fish Welfare Assurance System (FWAS). FWAS is based on the hazard analysis critical control points (HACCP) system. HACCP is an internationally acknowledged quality assurance system that is mandatory for the food industry in the EU and other countries outside of Europe. HACCP provides a management tool for food safety based on scientific principles while still being practicable, for example, small specialty shops that might be run by a single person, for example, a butcher. Briefly, the FWAS consists of the following seven principles: (1) perform a hazard analysis and risk assessment, (2) determine Critical Control Points (CCPs), (3) establish target levels and critical limits for each CCP, (4) establish monitoring procedures at each CCP, (5) establish corrective actions, (6) establish verification procedures, and (7) establish a record keeping system. The FWAS's structured approach is suitable to control proper stunning and killing of farmed fish in practice, as the basic premise is prevention rather than inspection.

Conclusion In the authors' view, the following approach is needed to put stunning and killing of farmed fish into practice. The first step is to establish the specifications needed for stunning and killing by registration of EEG and ECGs, behavioral

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observations and, when a stunning method is not instantaneous, supplementary stress-physiological analysis. Owing to the complexity of these methods, they can best be performed in a laboratory setting. Product quality analysis, which may be only feasible in a laboratory setting, needs to be taken into account, as for example, electrical and percussive stunning can lead to carcass damage. This might have adverse economic consequences and these should be prevented or minimized. For the assessment of the welfare aspects of stunning and killing in a commercial setting, it is likely that behavourial measurements supplemented with physical measures (e.g., voltage, amperage, dosage, and percussion forces depending on equipment used) might suffice. To control the subsequent implementation of stunning and killing of farmed fish in practice, the authors foresee that development of a processoriented assurance system is needed to safeguard and monitor fish welfare during stunning and killing.

Acknowledgment The preparation of this article was partly funded by the Dutch Ministry of Economic Affairs.

See also: Automation in the Meat Industry: Slaughter Line Operation. Species of Meat Animals: Finfish. Stunning: Electrical Stunning; Mechanical Stunning

Further Reading Braithwaite, V., Huntingford, F., Van den Bos, R., 2013. Variation in emotion and cognition among fishes. Journal of Agricultural and Environmental Ethics 26, 7–23. Broglio, C., Gómez, A., Durán, E., et al., 2005. Hallmarks of a common forebrain vertebrate plan: Specialized pallial areas for spatial, temporal and emotional memory in actinopterygian fish. Brain Research Bulletin 66, 277–281. Broglio, C., Rodríguez, F., Gómez, A., Arias, J.L., Salas, C., 2010. Selective involvement of the goldfish lateral pallium in spatial memory. Behaviorial Brain Research 210, 191–201. Codex Committee on Food Hygiene, 2009. Recommended international code of practice − general principles of food hygiene. In: Food Hygiene Basic Texts, fourth ed., pp. 3−34. Rome: Food and Agriculture Organisation of the United Nations, World Health Organization and Food and Agriculture Organization of the United Nations. Conte, F.S., 2004. Stress and the welfare of cultured fish. Applied Animal Behaviour Science 86, 205–223. Council Regulation (EC), 2009. On the protection of animals at the time of killing. No 1099/2009 Official Journal of the European Communities L303, 1–30. Dalla Villa, P., Marahrens, M., Calvo, A.V., et al., 2009. Final report on project to develop Animal Welfare Risk Assessment Guidelines on Transport-Project developed on the proposal CFP/EFSA/AHAW/2008/02, 143 pp. Available at: www.efsa.europa.eu/en/supporting/doc/21e.pdf (accessed 14.03.14). Digre, H., 2011. Slaughter methods and processing of farmed Atlantic cod (Gadus morhua) − Welfare aspects and quality. Doctoral Thesis at NTNU 2011:79. ISBN 978-82-471-2687-5. Durán, E., Ocaña, F.M., Broglio, C., Rodríguez, F., Salas, C., 2010. Lateral but not medial pallium ablation impairs the use of goldfish spatial allocentric strategies in a ‘holeboard’ task. Behaviorial Brain Research 214, 480–487. EFSA, 2008a. Scientific report of EFSA on Animal welfare aspects of husbandry systems for farmed Atlantic salmon (Question No EFSA-Q-2006-033). EFSA Journal 736, 1–122. Annex I.

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EFSA, 2008b. Scientific report of EFSA on Animal welfare aspects of husbandry systems for farmed European sea bass and Gilthead sea bream. (Question No EFSA-Q-2006-149). EFSA Journal 844, 1–89. Annex I. EFSA, 2008c. Scientific report of EFSA on Animal welfare aspects of husbandry systems for farmed trout. (Question No EFSA-Q-2006-147). EFSA Journal 796, 1–97. Annex I. EFSA, 2008d. Scientific report of EFSA on Animal welfare aspects of husbandry systems for farmed common carp. (Question No EFSA-Q-2006-148). EFSA Journal 843, 1–81. Annex I. EFSA, 2009. Scientific Opinion of the Panel on Animal Health and Welfare on a request from European Commission on general approach to fish welfare and to the concept of sentience in fish. EFSA Journal 954, 1–26. Erikson, U., Hultmann, L., Steen, J.E., 2006. Live chilling of Atlantic salmon (Salmo salar) combined with mild carbon dioxide anaesthesia I. Establishing a method for large-scale processing of farmed fish. Aquaculture 252, 183–198. Erikson, U., Lambooij, B., Digre, H., et al., 2012. Conditions for instant electrical stunning of farmed Atlantic cod after de-watering, maintenance of unconsciousness, effects of stress, and fillet quality − A comparison with AQUIS™. Aquaculture 324−325, 135–144. FAO, 2008. Glossary of Aquaculture Rome: Fisheries and Aquaculture Department, 424 pp. ISBN 978-92-5-005917-4. FAO, 2012. The State of Word Fisheries and Aquaculture 2012, 230 pp. Rome: FAO Fisheries and Aquaculture Department. ISBN 978-92-5-107225-7. Galhardo, L., Oliveira, R.F., 2009. Psychological stress and welfare in fish. Annual Review of Biomedical Sciences 11, 1–20. Huntingford, F.A., Adams, C., Braithwaite, V.A., et al., 2006. Current issues in fish welfare. Journal of Fish Biology 68, 332–372. Ito, H., Yamamoto, N., 2009. Non-laminar cerebral cortex in teleost fishes? Biology Letters 5, 117–121. Iversen, M.H., Økland, F., Thorstad, E.B., Finstad, B., 2013. The efficacy of Aqui-S vet. (iso-eugenol) and metomidate as anaesthetics in European eel (Anguilla anguilla L.), and their effects on animal welfare and primary and secondary stress responses. Aquaculture Research 44, 1307–1316. Kestin, S.C., van de Vis, J.W., Robb, D.H.F., 2002. A simple protocol for assessing brain function in fish and the effectiveness of stunning and killing methods used on fish. Vet Record 150, 302–307. Kooi, K.A., Tucker, R.P., Marshal, R.R., 1978. Fundamentals of Electro Encephalography, second ed. New York, NY: Harper and Row, pp. 125−145. Lambooij, B., Digre, H., Erikson, U., et al., 2013. Evaluation of electrical stunning of Atlantic cod (Gadus morhua) and turbot (Psetta maxima) in seawater. Journal of Aquatic Food Product Technology 22, 371–379. Lambooij, E., Digre, H., Reimert, H.G.M., et al., 2012. Effects of on-board storage and electrical stunning of wild cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) on brain and heart activity. Fisheries Research 127−128, 1–8. Lambooij, E., Gerritzen, M.A., Reimert, H., et al., 2008. A humane protocol for electro-stunning and killing of Nile tilapia in fresh water. Aquaculture 275, 88–95. Lambooij, E., Grimsbø, E., van de Vis, J.W., et al., 2010. Percussion and electrical stunning of Atlantic salmon (Salmo salar) after dewatering and subsequent effect on brain and heart activities. Aquaculture 300, 107–112. Lambooij, E., Van de Vis, J.W., Kloosterboer, R.J., Pieterse, C., 2002. Welfare aspects of live chilling and freezing of farmed eel (Anguilla anguilla, L.): Neural and behavioural assessment. Aquaculture 210, 159–169. Lines, J.A., Robb, D.H., Kestin, S.C., Crook, S.C., Benson, T., 2003. Electric stunning: a humane slaughter method for trout. Aquacultural Engineering 28, 141–154. Lines, J.A., Spence, J., 2012. Safeguarding the welfare of farmed fish at harvest. Fish Physiology and Biochemistry 38, 153–162. Lopes da Silva, H.F., 1983. The assessment of consciousness: general principles and practical aspects. In: Eikelenboom, G. (Ed.), Stunning of Animals for Slaughter. The Hague: Martinus Nijhoff, pp. 3–12. Morzel, M., Sohier, S., van de Vis, J.W., 2002. Evaluation of slaughtering methods of turbots with respect to animal protection and flesh quality. Journal of the Science of Food and Agriculture 82, 19–28.

Müller-Graf, C., Berthe, F., Grudnik, T., Peeler, E., Afonso, A., 2012. Risk assessment in fish welfare, applications and limitations. Fish Physiology and Biochemistry 38, 231–241. Nieuwenhuys, R., Ten Donkelaar, H.J., Nicholson, C., 1998. The Central Nervous System of Vertebrates, vol. 2, 1524 pp. Heidelberg: Springer-Verlag. Robb, D.F.H., Kestin, S.C., 2002. Methods used to kill fish: field observations and literature reviewed. Animal Welfare 11, 269–282. Roth, B., Birkeland, S., Oyarzun, F., 2009. Stunning, pre slaughter and filleting conditions of Atlantic salmon and subsequent effect on flesh quality on fresh and smoked fillets. Aquaculture 289, 350–356. Roth, B., Slinde, E., Imsland, A., Moeller, D., 2003. Effect of electric field strength and current duration on stunning and injuries in market-sized Atlantic salmon held in seawater. North American Journal of Aquaculture 65, 8–13. Roques, J., Abbink, W., Geurds, W., Van de Vis, H., Flik, G., 2010. Tailfin clipping, a painful procedure: Studies on Nile tilapia and common carp. Physiology and Behavior 101, 533–540. Roques, J.A.C., Abbink, W., Chereau, G., et al., 2012. Physiological and behavioral responses to an electrical stimulus in Mozambique tilapia (Oreochromis mossambicus). Fish Physiology and Biochemistry 38, 1019–1028. RSPCA, 2010. RSPCA welfare standards for farmed salmon. RSPCA, Horsham, UK. Available at: http://content.www.rspca.org.uk/cmsprd/Satelliteblobcol= urldata&blobheader=application%2Fpdf&blobkey=id&blobnocache=false& blobtable=MungoBlobs&blobwhere=1232991903901&ssbinary=true (accessed 25.09.13). Salas, C., Broglio, C., Durán, E., et al., 2006. Neuropsychology of learning and memory in teleost fish. Zebrafish 3, 157–171. Terlouw, C., Auperin, C.A.B., Berri, C., et al., 2008. Pre-slaughter conditions, animal stress and welfare: current status and possible future research. Animal 2, 1501–1517. Van de Vis, H., Kestin, S.C., Robb, D., et al., 2003. Is humane slaughter of fish possible for industry? Aquaculture Research 34, 211–220. Van de Vis, H., Kiessling, A., Flik, G., Mackenzie, S. (Eds.), 2012a. Welfare of Farmed Fish in Present and Future Production Systems. Heidelberg, Germany: Springer. Van de Vis, J.W., Poelman, M., Lambooij, E., Bégout, M.-L., Pilarczyk, M., 2012b. Fish welfare assurance system: Initial steps to set up an effective tool to safeguard and monitor farmed fish welfare at a company level. Fish Physiology and Biochemistry 38, 243–257. Van den Burg, E.H., Peeters, R.R., Verhoye, M., et al., 2005. Brain responses to ambient temperature fluctuations in fish: reduction of blood volume and initiation of a whole-body stress response. Journal of Neurophysiology 93, 2849–2855. Vargas, J.P., López, J.C., Portavella, M., 2009. What are the functions of fish brain pallium? Brain Research Bulletin 79, 436–440. Wendelaar Bonga, S.E., 1997. The stress response in fish. Physiological Reviews 77, 591–625.

Relevant Websites http://www.oie.int/en/international-standard-setting/aquatic-code/access-online/ htmfile=chapitre_1.7.4.htm Killing of farmed fish for disease control purposes. The World Organisation for Animal Welfare (OIE). http://www.oie.int/index.phpid=171&L=0&htmfile=chapitre_1.7.3.htm Welfare aspects of stunning and killing of farmed fish for human consumption. The World Organisation for Animal Welfare (OIE). http://www.oie.int/index.phpid=171&L=0&htmfile=chapitre_1.7.2.htm Welfare of farmed fish during transport. The World Organisation for Animal Welfare (OIE).

SUSTAINABLE MUSCLE FOODS INDUSTRY

E Kurt, Istanbul, Turkey R Klont, Vion Food, Boxtel, The Netherlands r 2014 Elsevier Ltd. All rights reserved.

Glossary Distiller’s Grains with Solubles (DGS) These are cereal by-products of the distillation process used for biofuel production. Feed Conversion Rate (FCR) It is a measure of an animal's efficiency in converting feed mass into increased body mass. Life cycle analysis (LCA) It is a technique to assess environmental impacts associated with all

Background Food production in general puts a lot of pressure on the environment. A growing global population to more than 9 billion people by 2050 will require approximately twice as much food, whereas high-quality proteins will become the limiting factor in a healthy diet according to the Food and Agriculture Organization (FAO). The demand for animal protein will continue to grow, especially in developing countries as they become more affluent. Production of meat requires substantial amounts of feed grains, which, in turn, uses vast amounts of arable land. Currently, 40% of the land on the earth is used for food production. On the one hand, it is important to produce enough food of high quality, but on the other hand, food production has not been optimized in the past with respect to sustainability issues. For every 1 kg of high-quality animal protein produced, livestock are fed between 3 and 10 kg of feed grain. Sustainability can be defined in many different ways, but in this article, it is interpreted as making more effective use of crops with reduced use of energy, reduced use of water, and minimization of losses through better chain management and logistics and optimal valorization of by-products and residues within the whole of the food chain. The standard methodology that is used to assess sustainability of any product or process is life cycle analysis (LCA). The total impact is often expressed in terms of the ‘carbon footprint,’ which gives an overall indication of the environmental impact of the product and its use. Although LCA is useful for the analysis of complete chains, it does not give insight into where inefficiencies are located and how these can be reduced. Profitability must be a component of ‘sustainability’ because no enterprise can continue unless it is profitable. LCA studies on meat production seldom extend beyond the agricultural production stage. Food production, preservation, and distribution consume a considerable amount of energy,

Encyclopedia of Meat Sciences, Volume 3

the stages of a product's life from conception to consumption. Polylactic acid (PLA) Biobased material from corn or sugarcane by-products that can be used in biorenewable packaging. Sustainability Defined as the effective use of agricultural crops with reduced use of energy and water, and a minimization of losses within the food chain and is still profitable.

which contributes to the total CO2 emission. LCA studies that cover more of the life cycle indicate that the agricultural production part is the main source for greenhouse gas emission in the life cycle of meat products. A recent study from the National Pork Board in the USA revealed that crop production, manure management, and retail distribution and consumption had the most impact on CO2 production in the pork production chain. Pig production from nursery to finishing accounted for 60% of emissions, whereas retail and consumer parts of the chain accounted for less than 10% each. This paper will focus on the entire production chain for meat and the opportunities that are available to optimize the efficiency and sustainability of meat production chains.

Livestock Production It is estimated that more than 60% of the arable land is used for the production of animal feeds. One of the approaches to reduce the environmental impacts of food is to optimize both the livestock and systems in which meat is produced. Animals need feed to grow and Table 1 shows that different types of animals require different energy input levels to produce 1 kcal of protein. Lamb and beef are the least efficient forms of animal protein production, but one has to keep in mind that these can also be grown on land that is less suitable for other types of agricultural production. Furthermore, both species can also be a by-product of wool or dairy production. The biological differences will remain as pigs will never be able to eat grass and the higher yields of broilers are due to their relative small size in comparison with pigs and beef cattle. In organic agricultural systems, livestock have more freedom of activity resulting in a higher feed-to-gain ratio. Other important traits in livestock production that can be optimized are growth rate and feed conversion of animals. The animal breeding industry has been focusing on increasing lean

doi:10.1016/B978-0-12-384731-7.00211-7

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growth rate and improving feed conversion rates (FCR) in the past decades. This has reduced the total feed intake and age at slaughter in most species. Improvements in broiler genetics, nutrition, and other management changes in the period of 1957–2001 have resulted in 2001 broilers that reached processing time in one-third of the time required for a 1957 bird with more than threefold decrease in the amount of feed consumed. Similar improvements in productivity over the past 40 to 50 years can be shown for pigs. Genetic improvement has led to a reduction in greenhouse gas emission for broilers and pigs and global warming potential per kg of animal product in the past 20 years of up to 30%. Optimization of feed composition is a major tool toward more sustainable meat production systems. Livestock feed is produced out of different feed ingredients. These feed ingredients can be whole crops (e.g., grains, rapeseed, peas, and soybeans) or by-products (e.g., pulp and milling products). Animals are very well able to digest low-quality vegetable byproduct sources to produce high-quality meat proteins. Future research should focus on increased utilization of these types of lower quality by-products. Examples of alternative proteins for animal feed would not only be insect or algae proteins but also safe reintroduction of animal by-products. Concerns about food safety and the BSE crisis have understandably inhibited previous procedures of recycling animal and food waste, such as supplementing animal feed with rendered animal material. Beyond changes in behavior of the food industry, retailers, and the general public to reduce food wastage, imaginative yet safe systems are required to recycle biological material discarded throughout the meat production chain. Traditional protein sources for animal feed as soybean and rapeseed in the future will be replaced by distiller's grains with solubles (DGS). DGS are by-products of the production of bioethanol. Different developments, like the responsible soy initiative, aim at global solutions to improve the sustainability of agricultural food production.

use of all the by-product streams. Water is primarily used to ensure food safety and hygiene during operation. Overall water consumption has been reduced by recycling and reuse under stringent food safety restrictions. Refrigeration and production of hot water are the major energy-consuming activities in meat processing with lesser amounts used for lighting, motors, and the like. The Australian red meat industry recently published an industry environmental sustainability review in which they monitored the changes in water and energy usage between 2003 and 2008–09. Overall, there was a reduction in raw water usage by 11% and a reduction in waste water generation by 13% compared with 2003. Energy usage levels had increased by approximately 18% since 2003 because additional energy sources were included compared with 2003 and some of the companies had started value-added processes, which are more energy intensive. Similar results were found by Ramirez et al. for a 10-year period in which they analyzed energy use and energy efficiency developments for the meat industry in four different European countries. They concluded that energy consumption increased between 14% and 32%, partly due to a shift from beef to broiler and pork processing and due to an increased demand for value-added meat products. However, strong hygiene regulations could explain between one- and two-thirds of the increase, whereas the role of increasing shares of frozen and cut fresh meat was found not to be of significance. Energy-related issues will become even more important in food processing plants as increasing sales of ready-to-eat meals and a greater demand for different and flexible range of products by consumers will lead to a larger energy demand. These changes in consumer behavior, together with raised energy prices, hardened price competition, and potential policy instruments such as CO2 taxation will stimulate the meat industry to continue their focus on reduction in water and energy usage. Reduction in water and energy usage currently is an integrated part of the corporate social responsibility agenda of all global meat companies. In a case study, it was shown that, even in a modern meat plant where many energy-saving measures have taken place, there is still a technical potential for saving 30% of the external heat demand and more than 10% of the mechanical shaft work used in the plant. It should be kept in mind, depending on the species, that between 40% and 60% of the processed animal is directly suitable for human consumption, whereas the rest are useful by-products. Head, bones, skin, heart, lungs, intestines, and blood are removed in the slaughter process. None of these byproducts are wasted and are used for a wide variety of food, feed, and nonfood applications like gelatin, different protein hydrolysates, fats, bone powder, etc. A comprehensive overview of all the products that can be made from pigs include medicine, heart valves, brakes, chewing gum, porcelain, soap, toothpaste, cosmetics, conditioner, and biofuel.

Processing Optimization

New Product Development

The meat industry is continuously optimizing carcass and meat product processing conditions by using operational excellence projects to reduce costs of production and make better

Meat fulfils some key important nutritional requirements and is part of a healthy diet. Both a meat-based and a lactoovo vegetarian diet require significant quantities of

Table 1 Ratio of fossil energy input required to produce 1 kcal of animal protein Livestock and animal products

Ratio of energy input to protein output (kcal)

Lamb Beef cattle Eggs Swine Dairy (milk) Turkey Broilers

57:1 40:1 39:1 14:1 14:1 10:1 4:1

Source: Reproduced from Pimentel, D., Pimentel, M., 2003. Sustainability of meatbased and plant-based diets and the environment. American Journal of Clinical Nutrition 78 (Suppl.), 660S−663S.

Sustainable Muscle Foods Industry

nonrenewable fossil energy to produce and are not sustainable in the long term according to Pimentel and Pimental. However, approximately 1.3 billion people are employed, either directly or indirectly, in livestock production and processing and provide economic livelihood for societies in addition to the dietary contributions they provide. However, the meat-based diet requires more energy, land, and water resources than the lacto-ovo vegetarian diet. Except for Japan (with its high fish intake), meat is now the single largest source of animal protein in all affluent nations, and it remains among the most desirable, high-status foodstuffs in all countries. In some of the developed countries, there have been recommendations to reduce the average meat consumption without negatively affecting the healthy diet requirements. Consumers do not easily reduce or replace meat for more sustainable alternatives. Nonvegetarian households are reluctant to decrease meat consumption just for environmental reasons, specifically reduced carbon footprint. Furthermore, current meat substitutes are not comparable in sensory perception to real meat products, and there is a low level of repetitive purchase by nonvegetarian consumers. Meat was judged more positively overall, which explains the choice for meat. Substantial voluntary reductions of meat consumption are not very likely. Because a large part of the meat production is sold as minced or further processed products, it should be possible to incorporate varying shares of plant-derived proteins and fibers into meat products and thus increase their sustainability. Development of hybrid products with a similar sensory profile would be an option to reduce current meat consumption levels. A commercial example of such a hybrid product development can be found where minced meat has been mixed with 30% plant protein and fibers and reducing the fat content of the product as well. Another area of product development for the meat industry will be packaging. Even though packaging material represents a relatively small part of the carbon footprint from the meat production chain, it is perceived by consumers as having a negative impact on sustainability and being environmentally unfriendly. An increasing part of total meat production is sold as case-ready products using modified atmosphere conditions to increase shelf life of the products. The need for convenience and ease of preparation will increase the demand for different types of meat-packaging options. The purpose of food packaging is to preserve the quality and safety of the food it contains from time of production to time of consumption. The majority of the current meat-packaging materials are based on petroleum derivates. As petroleum costs are increasing, renewable packaging for meat, such as materials based on Polylactic acid (PLA) from corn or sugar cane by-products, will become more feasible in the future. Different bio-based materials have become available made from a variety of renewable and sustainable agricultural commodities that can be applied for meat products and that have been tested for retention of product quality characteristics, handling properties, and microbiological stability of muscle foods. With consumer demanding more environmentally friendly packaging, new and novel food grade packaging materials or technologies have been and continue to be developed.

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Conclusions The challenge for the next 50 years in meat production is to increase the productivity of major livestock species in order to address the food needs of the world, but at the same time minimizing the environmental impact. A number of technologies and techniques are available to continuously improve feed conversion, reproduction, and overall production efficiency in beef and dairy cattle, pigs, and poultry. New processing technologies will reduce the water and energy usage in animal processing and further processed meat production. Although a voluntary reduction in meat consumption is not very likely, it is possible to develop new minced-based meat products that are enhanced with plant and/or by-product proteins and that taste and present nutritional value that is as good as found in the original products.

Further Reading Cutter, C.N., 2006. Opportunities for bio-based packaging technologies to improve the quality and safety of fresh and further processed muscle foods. Meat Science 74, 131–142. Eilert, S., 2005. New packaging technologies for the 21st century. Meat Science 71, 122–127. Elferink, E.V., Nonhebel, S., 2007. Variations in land requirements for meat production. Journal of Cleaner Production 15, 1778–1786. FAO, 2009. Declaration of the World Summit on Food Security, 16−18 November 2009. Rome, Italy: Food and Agricultural Organization of the United Nations. Foster, C., Green, K., Bleda, M., Dewik, P., 2006. Environmental impacts of food production and consumption. A Final Report to the Department of Environment, Food and Rural Affairs. London: Manchester Business School, Defra. Fritzson, A., Berntsson, T., 2006. Efficient energy use in a slaughter and meat processing plant − Opportunities for process integration. Journal of Food Engineering 76, 594–604. Gilland, B., 2002. World population and food supply. Can food production keep pace with population growth in the next half century? Food Policy 27, 47–63. Havenstein, G.B., Ferkel, P.R., Qureshi, M.A., 2003. Growth, livability, and feed conversion of 1957 versus 2001 broilers when fed diets representative 1957 and 2001 broiler diets. Poultry Science 82, 1500–1508. Hoek, A.C., 2010. Will novel protein foods beat meat? Consumer acceptance of meat substitutes − A multidisciplinary research approach The Netherlands: Thesis Wageningen University. ISBN 978-90-8585-536-1. Hume, D.A., Whitelaw, B.A., Archibald, A.L., 2011. The future of animal production: Improving productivity and sustainability. Journal of Agricultural Science 1–8. Meindertsma, C., 2008. Pig 05049, second ed. Flocks Uitgeverij. ISBN 978-90812413-1-1. M.L.A., Meat & Livestock Australia, 2010. Industry environmental sustainability review 2010. Published June 2011. Sydney, NSW: Meat and Livestock Australia. ISBN 978174915693. Nonhebel, S., 2005. Renewable energy and food supply: Will there be enough land? Renewable and Sustainable Energy Reviews 9 (2), 191–201. Nonhebel, S., Moll, H.C., 2001. Evaluation of options for reduction of greenhouse gas emissions by changes in household consumption patterns. IVEM Research Report (OS) 106. The Netherlands: University of Groningen. Pimentel, D., Pimentel, M., 2003. Sustainability of meat-based and plant-based diets and the environment. American Journal of Clinical Nutrition 78 (Suppl.), 660S–663S. Ramirez, C.A., Patel, M., Blok, K., 2006. How much energy to process one pound of meat? A comparison of energy use and specific energy consumption in the meat industry of four European countries. Energy 31, 2047–2063. Roy, P., Nei, D., Orikasa, T., et al., 2009. A review of life cycle assessment (LCA) on some food products. Journal of Food Engineering 90, 1–10. Smil, V., 2002. Worldwide transformation of diets, burdens of meat production and opportunities for novel proteins. Enzyme and Microbial Technology 30, 305–311. Van Der Steen, H.A.M., Prall, G.F.W., Plastow, G.S., 2005. Application of genomics to the pork industry. Journal of Animal Science 83 (E Suppl.), E1–E8.

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Relevant Websites ftp://ftp.fao.org/docrep/fao/Meeting/018/k6050e.pdf Food and Agricultural Organization of the United Nations. www.pork.org/sustainability Pork Checkoff from the National Pork Board in Des Moines USA. www.responsiblesoy.org Round Table on Responsible Soy Association.

www.smithfieldcommitments.com/csr-reports Smithfield. www.hackplus.de VION Food Group. www.vionfoodgroup.com/flipbook/annual-report-2010 VION Food Group.

T TENDERIZING MECHANISMS

Contents Chemical Enzymatic Mechanical

Chemical DL Hopkins, NSW Department of Primary Industries, Cowra, NSW, Australia Alaa El-Din A Bekhit, University of Otago, Dunedin, New Zealand r 2014 Elsevier Ltd. All rights reserved. This article is a revision of the previous edition article by DL Hopkins, volume 3, pp 1363–1369, © 2004, Elsevier Ltd.

Glossary Ageing It is the process of meat tenderization that occurs over time – it commences after rigor mortis. Contractile proteins It includes actin and myosin, which form the thin and thick filaments of skeletal muscle. These two proteins interact chemically (to form actomyosin), which gives muscle the ability to contract and relax. Associated with actin are the proteins troponin and tropomyosin. Costameres It connects Z-disks to the sarcolemma and are made up of proteins such as talin, vinculin, desmin, and dystrophin. Cytoskeletal proteins These are a set of filamentous structural proteins (includes actin, titin, nebulin, and desmin). Electrical stimulation Application of an electric current through a carcass postmortem that accelerates the rigor process. Myofibril It is comprised of contractile, structural, and regulatory proteins. The contractile protein is composed of myofilaments, which are in turn made up of thin and thick filaments. Structural proteins include titin and nebulin. Titin is the largest protein in skeletal muscle (approximately 3700 kDa) and it provides elasticity to the sarcomere. The regulatory proteins include troponin and tropomyosin.

Encyclopedia of Meat Sciences, Volume 3

Proteolysis It is the degradation of proteins into smaller subunits that occurs with ageing and also during turnover of living muscle. Rigor It is a term for individual muscle fibres that have been depleted of adenosine triphosphate and the actomyosin bond has formed. Rigor mortis It is a term used when muscles stiffen after all muscle fibres enter rigor. Sarcomere The basic unit of skeletal muscle defined by the distance between two Z-disks. Z-disks are dense protein structures into which the contractile protein actin is attached along with proteins such as titin and nebulin. Z-disks are the anchor points for the contractile proteins that allow contraction and relaxation. Shear force It is the force (N) applied to a standardized piece of cooked meat to shear it. Shortening It is a process that occurs when prerigor muscle is cooled below 10 °C when the pH is still above 6.0. Additionally it also occurs as muscles enter rigor at high temperatures (rigor shortening). Tenderization It is the enzymatic process that takes place after rigor mortis that makes meat tender. Ultimate pH It is the pH attained when muscles reach rigor mortis.

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Tenderizing Mechanisms | Chemical

The process that leads to an improvement in tenderness can be termed ‘tenderization’ and this is driven by proteolysis of myofibrillar, cytoskeletal, and costameric proteins. Proteolysis of some of the myofibrillar proteins can precede tenderization (i.e. before rigor mortis) and the degree of disruption of these proteins (such as titin and nebulin) will influence the final stage of meat tenderness. Other proteins, like actin and myosin, are not generally degraded under normal storage temperatures. The introduction of exogenous solutions containing ions such as Ca2+ or Na+ has been shown to impact the tenderization of meat. The action of Ca2+ is strongly linked to the activation of the calpains as opposed to altering protein structure per se, whereas Na+ based solutions can lead to solublisation of proteins and thus improve tenderness. Connective tissue provides support in muscle at a number of levels via the endomysium, perimysium, or epimysium and maintains the integrity of the contractile apparatus. This connective tissue is not significantly degraded during ‘normal’ tenderization. However chemical mechanisms have been implicated in the solubility of connective tissue, particularly based on the use of organic acids. Commercial application of systems to introduce chemical-based solutions to meat have been restricted to vascular infusion, but the efficacy of this approach for improving tenderness is debatable.

Rigor Bonding After death, muscle filaments are in a continual state of contraction and relaxation. As adenosine triphosphate (ATP) is depleted, the filaments enter rigor and a contracted state, but this process does not occur uniformly throughout a muscle fiber. As a consequence of the interaction between the contractile proteins actin and myosin, and other associated filament proteins, the overlap between thick and thin filaments increases, leading to an increase in toughness and a decrease in the width of the A band within the sarcomere. The degree of overlap will be influenced by temperature, with extreme contraction (increased overlap) occurring under low temperatures, known as ‘cold shortening.’ Based on theoretical studies of muscle biochemistry, several workers have proposed that the binding ‘state’ of actin and myosin can be manipulated as fibres enter rigor. These binding states are proposed to arise through a change in contact between myosin heads (S1) and specific regions of actin monomers reflected by the sequences of amino acids in different regions. The relative proportion of different states of actin–myosin interactions is proposed to vary in relative proportions as muscle enters rigor. The hypothesis is that this would affect subsequent toughness, and so changes in conformational states of actomyosin at rigor could explain the toughening of muscle at this stage. Several studies have linked changes in the ease with which actomyosin can be dissociated (as an indicator of binding strength) and tenderization, but these studies did not provide definite evidence to support the hypothesis. Indeed, when the potential confounding effects of proteolysis (due to endogenous enzymes) have been taken into account, the hypothesis is not supported.

Infusion/injection of meat with ionic compounds in solution termed ‘meat enhancement’ can manipulate several biochemical processes, depending on the postmortem time of injection. For example, prerigor infusion can have a dramatic effect on the rate of glycolysis, the rate and state of contraction, the oxidative processes and rate of the proteolysis whereas postrigor injection will affect mainly proteolysis and oxidative processes. Early prerigor enhancement can result in dramatic toughening. The impact of the infused compounds on meat quality will be greatly dependent on the postmortem time of the treatment (reflecting the pH and the temperature of the meat), the concentration of the infused compounds (level of activation or modification) and the method of infusion (the distribution of the compounds in the meat). Each combination of the above factors can lead to unique outcomes for different species and within these combinations a set of factors can be optimized for the best outcome.

Injection of Metal Ions and Ionic Strength Metal ions such as Ca2+ and Mg2+ have many functions in regulating muscle contraction and enzyme activity, and for this reason extensive research has been conducted to examine the effect on tenderization when such ions are injected into muscle. There is a significant rise in ionic strength as muscle enters rigor, without any exogenous introduction of ions, and this has been proposed to contribute to tenderization. The rise in ionic strength mirrors the decline in pH (Figure 1) and is attributed to an alteration of protein structure and the release of bound ions and metabolites. A rise in osmolality has been shown to increase the solubility of proteins, which could make them more liable to enzymatic degradation and thus be part of a synergistic mechanism. The extent of the increase in ionic strength is muscle specific, with higher osmolalities in fasttwitch glycolytic muscles. The introduction of metal ions into muscle has been studied extensively as a means of understanding the potential synergy between a rise in ionic strength and enzyme activity. Prerigor injection of high ionic solutions creates an atypical 7

550 500

6.5

450 400

6

350 5.5

Osmolality (mOs)

Introduction

pH

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300 0

7

9

13

25

50

Time postmortem (h) pH

Osmolality

Figure 1 Postmortem decrease in muscle pH ( ) and increase in osmolality ( ) in bovine Musculus longissimus. Adapted from Ouali, A., Vigon, X., Bonnet, M., 1991. Osmotic pressure changes in postmortem bovine muscles: Factors of variation and possible causative agents. Proceedings 37th International Congress of Meat Science and Technology, Kulmbach, pp. 452–455.

Tenderizing Mechanisms | Chemical environment within the muscle, and this may by itself result in premature membrane rupturing and the release of endogenous enzymes. Isolating the mode of action of ion injection on tenderization has been a major challenge since ions such as Ca2+ can cause shortening when injected prerigor as well as activate endogenous enzymes. One approach that has been used to speed up the onset of rigor is electrical stimulation, so that earlier postmortem injection of ions could occur. Infusion with 0.3 mol l−1 CaCl2 has been shown to accelerate tenderization and lower shear force values compared with control samples and the reduction in shear force has been attributed to an increased level of activity of μ-calpain and also m-calpain at the highest concentration of CaCl2 . The requirement for such high levels of CaCl2 may reflect the barriers that exist to the translocation of ions into the cell; a high level could ensure that some of the ions reach the target enzymes, by effectively swamping the cells. Injection of hot-boned muscle (prerigor) with 0.3 mol l−1 CaCl2 does elicit significant shortening, but the muscle is still significantly more tender than control muscle, or muscle injected with 0.15 mol l−1 NaCl. In this case the effective Ca2+ concentration would be much higher than would occur intrinsically because it has been clearly shown that maximum Ca2+ concentration is not reached until the postrigor period. A summary of the reported effects of Ca2+ on tenderness is given in Table 1. Injection of sodium chloride (NaCl), combined with phosphates, will enhance the ability of muscle proteins to bind with water and could reflect increased solubility of these proteins and this is the principle applied for the brine treatment of pork. Sodium chloride and polyphosphates accelerate the degradation rates of titin and troponin-T as well as the appearance of 95 and 30 kDa degradation products, which leads to higher tenderization rates and these effects have been attributed to an increased pH due to the high buffering capacity of polyphosphates. In some instances, sodium pyrophosphate has been injected into muscle in combination with NaCl. Although this has been observed to cause increased calpain activity leading to a reduction in shear force, the ability of pyrophosphate to compete with ATP binding sites on myosin, and thus reduce the extent of muscle contraction, is also a possible explanation for the reduction in toughness. When myofibrils that have been treated to remove endogenous proteolytic enzymes (i.e. calpains), are incubated with 0.3 mol l−1 CaCl2, some key myofibrillar proteins show no degradation with time, indicating that protein solubility alone cannot explain tenderization. Equally, this is consistent with activation of the calpains as the major contender for the mechanism that drives tenderization. A major drawback of injection with CaCl2 is that the meat tends to be regarded as having a bitter flavour and to be less acceptable to consumers, due to the fact that Ca2+ can stimulate lipoxygenase activity and the mitochondrial respiration process leading to higher rate of oxidative processes. For this reason, commercial adoption of CaCl2 infusion into meat has been limited. The extent of the synergy between enzyme activity and changes in ionic strength is yet to be fully clarified.

Injection of Acids and Other Compounds A number of organic acids such as acetic, citric, and lactic have been used to tenderize meat. Administration is often by

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marination, but this requires extended storage periods for penetration into the meat. A number of studies have investigated the efficacy of these acids after injection into meat. These acids cause a significant decrease in pH, creating an environment that is optimal for cathepsin activity (these are lysosomal proteases), which is confirmed by the degradation of proteins such as myosin, a protein that is not degraded under normal (control) postmortem conditions. A drop in pH leads to swelling of the meat. Another effect of this treatment is the weakening/solubilization of perimysial collagen and lowering of the temperatures required for denaturation of connective tissue. On the whole, organic acids lead to an increase in meat tenderness (Table 2). Since the effect of acid injection is largely dependent on the buffering capacity and overall pH reduction in meat, the type of acid used is very important to achieve desired quality attributes. Lactic acid lowers the pH compared with citric and acetic acids, and illicits more dramatic changes in the meat. Combinations of ions and organic acids have also been used to enhance tenderization.

Vascular Infusion Another approach that has been developed commercially is the vascular infusion of a chemical mix into carcasses via the arteries immediately after death at a rate of 10% of live weight. The chemicals include sugars, phosphates, and sometimes salts. A reduction in toughness has been reported in a couple of studies using this methodology (Figure 2), although other studies have reported no difference in either objective tenderness (shear force) or consumer assessments of tenderness. One of the reports of increased tenderization was associated with increased fragmentation of myofibrils and increased degradation of myofibrillar proteins such as troponin. Unfortunately, the methodology does cause paler meat colour, with higher weep, and thus tends to be less acceptable to retailers, wholesalers and consumers. The main advantage is the increase in carcass weight resulting in increased returns per kilogram of carcass weight. The mode of action that occurs through use of the chemicals has not been confirmed, but could include disruption of muscle cells and increased proteolysis or changes in osmolality. The rate of glycolysis increases with infusion and this may in turn accelerate the activity of the calpains. More recently, this same approach has been investigated, but with the infusion of an ice-slurry throughout the carcase, which has been shown to reduce shear force, but the mechanism was not quantified. Infusion of plant extracted enzymes has also been effective at reducing shear force. Related to this concept is the prerigor injection or infusion of carcases to manipulate the rate of glycolysis and thus pH fall. It has been reported that prerigor injection of either sodium fluoride or sodium citrate can increase the level of muscle glycogen and thus reduce the absolute decline in pH. Given the link between pH and the activity of the calpains, this could presumably enhance the rate of tenderization. These compounds have resulted in a higher ultimate pH, a reduction in sarcomere length, and in case of sodium citrate a reduction in shear force (Figure 3). For the immediate postmortem period when the citric acid cycle is still operative, citrate is produced, which has an inhibitory effect on

0.1 mol l−1 (10% of cut weight)

0.075 mol l−1 (10% of animal liveweight) 0.15 mol l−1 (10%) 0.15 mol l−1 (10%) 0.3 mol l−1 (10%) 0.3 mol l−1 (10%) 0.3 mol l−1 (10%) 0.175 mol l−1 (10% of cut weight) 0.175 mol l−1 (10% of cut weight) 0.175 mol l−1 (10% of cut weight) Water Water Water 0.175 mol l−1 (10%) 0.175 mol l−1 (10%) 0.175 mol l−1 (10%) Water Water Water 0.2 mol l−1 (5%) 0.2 mol l−1 (5%) 0.2 mol l−1 (10%) 0.2 mol l−1 (10%) 0.25 mol l−1 (5%) 0.25 mol l−1 (5%) 0.25 mol l−1 (10%) 0.25 mol l−1 (10%) 0.25 mol l−1 (10%) 0.25 mol l−1 (10%) 0.3 mol l−1 (10% of cut weight)

LL (bovine)

24

24

1 12 24 1 12 24 1

6

6

0

2 6

10

24

6

4

2

2

16.9% 4.4%

−26.5% – − 19.6% − − 9.8% − − 9.8% 6.7% 11.8% 6.4% 13.7% 8.9% 3.7% 15.7% −4.3% 1.8% − 2.9 −7.9 − −29.2 −25.6 −15.0 −22.4 −13.1 − −21.7 −25.6 −23.7 −10.9 −31.4 −17.1 −15.6 −25.0 −8.5 −3.4 −24.8 −1.8 −8.5 −33.1 −20.3 −13.5 −70.6c −50.0

LL SM TB LL SM TB LL SM TB LL SM LL SM LL SM TB LL SM TB SM (bovine)

2

–

0.5

−12.6

LL (bovine)

TB

−

Sensory tendernessb

–

% Shear forcea

−2.9

1–2

Ageing Temperature (°C)

SM

0.5

Postmortem time of injection (h)

10.2%

1 6 1 6 1 6 1 7

Ageing time (days)

−1.7 11.7 −28.1 −14.3 −60.0 −45.5 −50.3 −21.9

LL (ovine)

Muscle/Species

Summary of effects of various meat calcium (CaCl2) infusion tenderization treatments applied during the post mortem period

Dose level and concentration of added solution

Table 1

Rousset-Akrim et al. (1996)

Boleman et al. (1995)

Wheeler et al. (1993)

Koohmaraie et al. (1989)

References

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LL (bovine) SM

LL (bovine)

b

Difference from control (negative means tender, positive means tougher). Tenderness rating (difference from control positive means more tender). c Myofibrillar resistance by compression method. Abbreviations: LL, Longissimus lumborum; SM, Semimembranosus; TB, Triceps brachii.

a

0.3 mol l−1 (10% of animal liveweight)

0.2 mol l−1 (5% of cutweight)

14 2 6 14 7 35 7 35 14 0.1

36

48

24

2–4

1

−43.9 −53.6 −44.2 −39.3 −23.6 −23.3 −19.4 −4.3 65.7 −2.1

−9.6% 40.8% 40.0% 13.5% 17.3% 12.1% 12.7% 13.1% −19.7% 1.8%

Dikeman et al. (2003)

Wheeler et al. (1997)

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Tenderizing Mechanisms | Chemical

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Table 2 Sensory assessment (ease of first bite and chewiness; 1¼extremely tough to 10 ¼extremely tender) for beef Musculus pectoralis profundus treated with 0.5 mol l−1 lactic acid at either 1 or 24 h postmortem and aged for 2 or 14 days

Ease of first bite Chewiness Ease of first bite Chewiness

Lactic acid (1 h)

Lactic acid (24 h)

Control

Ageing period (days)

6.7a 6.0a 6.0a 5.7a

7.4a 6.3a 6.4a 6.1a

4.3b 5.3a 4.2b 4.4b

2 2 14 14

Shear force (N)

Note: Means followed by a different letter (a, b) within a row are significantly different (Po0.05). Source: Adapted from Berge, P., Ertbjerg, P., Larsen, L.M., et al., 2001. Tenderization of beef by lactic acid injected at different times post mortem. Meat Science 57, 347–357.

100 90 80 70 60 50 40 30 20 10 0 Ovine loin Infused Control

Figure 2 Effect on the shear force of ovine loin (24 h postmortem) after infusing carcasses with a solution of 0.1% maltose, 0.21% glycerine, 0.23% dextrose, and 0.14% blend of sodium and potassium tripolyphosphate in water. Adapted from Farouk, M.M., Price, J.F., Salih, A.M., 1992. Post-exsanguination infusing of ovine carcasses: Effect on tenderness indicators and muscle microstructure. Journal of Food Science 57, 1311–1315.

Similarly, injection of sodium bicarbonate has been found to slow the rate of pH decline in porcine muscle, decrease drip loss and darken meat, but again no mode of action has been proposed. It is probable that the response was mediated through a buffering effect whereby the free hydrogen ions produced as a result of glycolysis become complexed with the bicarbonate. Selection of compounds that can inhibit critical steps in the glycolytic pathway will control the decline in pH. Another approach would be to increase the concentration of creatine phosphate to buffer ATP levels and thus prolong the postmortem time period before ATP is utilised and, therefore, prevent an immediate fall in pH. The inhibition of AMPactivated protein kinase (AMPK) would also presumably lead to a reduction in the rate of pH fall postmortem, as would regulation of the activity of glycogen debranching enzyme (GDE), by a reduction in glycogenolysis. A delay in activity of GDE until the carcase temperature dropped below 39 °C would result in a reduction in the rate of pH decline. Whichever mechanism was applied, the critical concentration of the inhibitor would have to be determined, for high concentrations would potentially lead to a reduction in glycolysis to the extent that the final pH was too high creating other quality issues.

Shear force (N)

70 60 50

Nonenzymatic Tenderization Meditated by Calcium Ions

40

There is a hypothesis that Ca2+ ions cause nonenzymatic weakening of the myofibrillar structure, and thus tenderization. It is suggested that the significant rise in the concentration of free calcium as rigor develops leads to fragmentation of proteins such as nebulin, desmin, and titin and the weakening of Z-disk proteins through the liberation of phospholipids. Several facts bring into question the validity of this theory: (1) when myofibrils, which have been treated to remove endogenous proteolytic enzymes (i.e., calpains), are incubated with 0.3 mol l−1 CaCl2, some key myofibrillar proteins show no degradation with time; (2) troponin T is readily degraded in postmortem muscle, but there is no claim that it is directly affected by calcium; (3) when Triton X-100, which causes a release of Ca2+ ions, is combined with a calpain inhibitor, toughness is not reduced; (4) inhibition of specific proteases has been found to prevent tenderization in the presence of an increasing concentration of free calcium; and (5) there is clear evidence for protein degradation/deposition in living muscle as a result of calpain activity, so there is no reason to suggest activity to cease in postmortem muscle, particularly in the early period of rigor development.

30 20 10 0 Triceps brachii

Supraspinatus Semimembranosus Muscle

Control

Sodium citrate

Figure 3 Effect on the shear force of bovine muscles (72 h post mortem) after prerigor injection with a solution of 200 mmol l−1 sodium citrate compared with noninjected muscle. A significant difference (Po0.05) in shear force between treatments was found for the supraspinatus muscle. Adapted from Jerez, N.C., Calkins, C.R., Velazco, J., 2003. Prerigor injection using glycolytic inhibitors in lowquality beef muscles. Journal of Animal Science 81, 997–1003.

phosphofructokinase. Because this enzyme is an important regulatory enzyme in glycolysis, this may partially explain the apparent reduction in glycolysis reported by the injection of sodium citrate.

Tenderizing Mechanisms | Chemical It has been shown using autoradiography that Ca2+ ions bind to titin, and more specifically by using fluorescence detection they bind to the major sub fragment of this degraded protein. Since calpains bind to Ca2+ ions for activation and titin has been shown to be a good substrate for these enzymes, these results are not inconsistent with the proposed role of the calpains in tenderization. Also, this partially reconciles some of the results to emerge from the theory that Ca2+ ions cause nonenzymatic weakening of the myofibrillar structure.

See also: Carcass Composition, Muscle Structure, and Contraction. Conversion of Muscle to Meat: Aging. Tenderizing Mechanisms: Enzymatic; Mechanical

Further Reading Brown, T., Richardson, I.R., Wilkin, C.-A., Evans, J.A., 2009. Vascular perfusion chilling of red meat carcasses − a feasibility study. Meat Science 83, 666–671. Boleman, S.J., Boleman, S.L., Bidner, T.D., McMillin, K.W., Monlezun, C.J., 1995. Effects of postmortem time of calcium chloride injection on beef tenderness and drip, cooking and total loss. Meat Science 39, 35–41. Dikeman, M.E., Hunt, M.C., Schoenbeck, J., et al., 2003. Effects of postexsanguination vascular infusion of cattle with a solution of saccharides, sodium chloride, and phosphates or with calcium chloride on meat quality and sensory traits of steaks and ground beef. Journal of Animal Science 81, 156–166. Hopkins, D.L., Thompson, J.M., 2001. The relationship between tenderness, proteolysis, muscle contraction and dissociation of actomyosin. Meat Science 57, 1–12. Hopkins, D.L., Thompson, J.M., 2002. Factors contributing to proteolysis and disruption of myofibrillar proteins and the impact of tenderisation in beef and sheep meat. Australian Journal of Agricultural Research 53, 149–166.

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Kauffman, R.G., van Laack, R.L.J.M., Russell, R.L., et al., 1998. Can pale, soft exudative pork be prevented by post-mortem sodium bicarbonate injection? Journal of Animal Science 76, 3010–3015. Ke, S., Huang, Y., Decker, E.A., Hultin, H.O., 2009. Impact of citric acid on the tenderness, microstructure and oxidative stability of beef muscle. Meat Science 82, 113–118. Koohmaraie, M., Crouse, J.D., Mersmann, H.J., 1989. Acceleration of postmortem tenderization in ovine carcasses through infusion of calcium chloride: Effect of concentration and ionic strength. Journal of Animal Science 67, 934–942. Kylä-Puhju, M., Ruusunen, M., Puolanne, E., 2005. Activity of porcine muscle glycogen debranching enzyme in relation to pH and temperature. Meat Science 69, 143–149. Lee, S., Stevenson-Barry, J.M., Kauffman, R.G., Kim, B.C., 2000. Effect of ion fluid injection on beef tenderness in association with calpain activity. Meat Science 56, 301–310. Ouali, A., 1992. Proteolytic and physiochemical mechanisms involved in meat texture development. Biochimie 74, 251–265. Rousset-Akrim, S., Got, F., Bayle, M.C., Culioli, J., 1996. Influence of CaCl2 and NaCl injections on the texture and flavour of beef. International Journal of Food Science and Technology 31, 333–343. Stephens, J.W., Dikeman, M.E., Unruh, J.A., Haub, M.D., Tokach, M.D., 2006. Effects of pre-rigor injection of sodium citrate or acetate, or post-rigor injection of phosphate plus salt on post-mortem glycolysis, pH, and pork quality attributes. Meat Science 74, 727–737. Takahashi, K., 1996. Structural weakening of skeletal muscle tissue during postmortem ageing of meat: The non-enzymatic mechanism of meat tenderization. Meat Science 43, s67–s80. Wheeler, T.L., Koohmaraie, M., Lansdell, J.L., Siragusa, G.R., Miller, M.F., 1993. Effects of post-mortem injection time, injection level, and concentration of calcium chloride on beef quality traits. Journal of Animal Science 71, 2965–2974. Wheeler, T.L., Koohmaraie, M., Shackelford, S.D., 1997. Effect of post-mortem injection time and post injection aging time on the calcium-activated tenderization process in beef. Journal of Animal Science 75, 2652–2660.

Enzymatic E Huff-Lonergan, Iowa State University, Ames, IA, USA r 2014 Elsevier Ltd. All rights reserved. This article is a revision of the previous edition article by DL Hopkins, E Huff-Lonergan, volume 3, pp 1363–1369, © 2004, Elsevier Ltd.

Glossary Calpains A group of enzymes, including m-calpain and m-calpain, that when activated by calcium degrade the cytoskeletal proteins. Calpastatins Endogenous inhibitor of m- and m-calpains. Cathepsins Cysteine proteases that degrade many different types of proteins. Contractile proteins Muscle proteins, such as actin and myosin, that are directly involved in the contractile process and minimally involved in tenderization.

Cytoskeletal proteins A set of structural proteins (includes titin, nebulin, and desmin) are denatured by calpains during tenderization. Endogenous proteases Proteases involved in muscle remodeling in life that take on the role of degrading cytoskeletal proteins postmortem. Exogenous enzymes Protease enzymes usually of plant material that when applied to meat degrade myofibrillar and connective tissue proteins.

Introduction

Enzymatic Tenderization

The process of meat tenderization is a complex phenomenon. It is accomplished naturally by the presence of endogenous enzymes and it can be augmented by the application of exogenous enzymes, typically purified from plant sources. In postmortem muscle, natural tenderization begins at slaughter and continues to occur while the meat is held at refrigerated temperatures over the next 2–3 weeks. This natural tenderizing process is often referred to as ‘aging’ the product. Tenderization via natural aging is done by the actions of enzymes in the muscle that function to regulate the growth and repair of living muscle, often by serving a role in the initiation of the removal of damaged proteins so that new proteins can be inserted into the appropriate muscle structure. The majority of these endogenous enzymes act on the structures of the myofibril, the main contractile organelle of the muscle cell. The tenderization that occurs via these endogenous enzymes starts at death and is essentially slowed or has ceased by 7 days postmortem in most species. Tenderization via the application of exogenous enzymes is generally less specific than endogenous enzymes. These enzymes target not only myofibrillar proteins but also the connective tissue proteins of the muscle. Most plant enzymes have the capacity to tenderize the product to a greater degree than is possible with endogenous enzymes, leading to the need for the processor to carefully monitor the process to avoid ‘overtenderizing’ the product and creating an overly soft, or even ‘mushy’ texture to the meat. Both types of enzymes are important in the production of tender meat products. An appropriate understanding of the enzyme systems being relied on for tenderization is important to allow maximal tenderness development in a given product.

Role of Endogenous Proteases

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During aging of meat, major structural changes occur in the muscle tissue. Many of these changes are associated with myofibrils, the contractile elements of muscle cells, and their linkages to the cell membrane (sarcolemma) through the cytoskeletal network. As myofibrils make up approximately 80% of the volume of the muscle cell, disruption of myofibrillar structure and, in particular, the cytoskeletal network has the greatest influence on meat tenderness during aging. Changes in the connective tissue are minimal during aging, although the amount of connective tissue that varies between different cuts influences the basic tenderness. Degradation of some proteins linking myofibrils to the sarcolemma and to each other has been observed during the early postmortem period. Other changes that are correlated with increased tenderness include breakages within the myofibrils themselves, particularly within the I-band. These breakages lead to increased fragility and fragmentation of the myofibrils. The histochemical and biochemical evidence indicates that much of the tenderization associated with postmortem aging is due to the action of the enzymes, which are known to be endogenous to the muscle. Some of the major myofibrillar and cytoskeletal proteins that are known to be degraded early during postmortem aging include (but are not limited to) titin, nebulin, desmin, and troponin-T. Interestingly, the most abundant proteins of the myofibril, actin and myosin, are not significantly degraded during postmortem aging.

Cathepsins Early research on the mechanism responsible for the development of meat tenderness during aging focused on the cathepsins. The cathepsins are endogenous proteases found in

Encyclopedia of Meat Sciences, Volume 3

doi:10.1016/B978-0-12-384731-7.00248-8

Tenderizing Mechanisms | Enzymatic lysosomes in living muscles. The most frequently studied cathepsins with respect to meat tenderness include cathepsins B, D, L, and H. The majority of the cathepsins are active at acidic pH values (usually between pH 5 and 6). These proteases were originally of interest because in living tissue lysosomes are one of the major sites of protein degradation. Additionally, these enzymes are active at acidic pH values, near the pH values found in postrigor meat.

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be stressed that other enzyme systems like the serine proteases and the proteasomes may have a role in postmortem proteolysis. Recent studies on the proteasome endopeptidase complex (EC 3.4.25.1) in bovine skeletal muscle have suggested that it could play a role in protein degradation late in the aging process. At this stage, however, there is insufficient evidence to substantiate involvement of these other enzyme systems.

Characteristics of the cathepsins Cathepsin B (EC 3.4.22.1) is a glycoprotein that has a molecular weight of approximately 25 000. It is a cysteine protease and has been shown to have activity over the pH range of 4–6.5. Cathepsin B degrades many proteins in the muscle, including myosin and actin. Cathepsin D (EC 3.4.23.5) is an aspartyl protease with an approximate molecular weight of 42 000. This glycoprotein has been shown to have activity over the pH range 2.5–5.0. Like cathepsin B, cathepsins D and L (EC 3.4.22.15) will degrade myosin and actin. Cathepsin L has also been shown to have activity against α-actinin, troponin-T, and troponin-I and is active over the pH range 3.0–6.5. Cathepsin H (EC 3.4.22.16) is a cysteine protease with a molecular weight of approximately 25 000 and is active from pH 5.5 to 6.5. Like all of the cathepsins mentioned in this article, cathepsin H has a high specific activity against myosin. In addition to degrading many myofibrillar proteins, several of the cathepsins have the ability to hydrolyze connective tissues, especially cathepsins B and L. Cathepsin B has been shown to have activity against collagen and proteoglycans. Cathepsin L has been shown to have activity against collagen, proteoglycans, and elastin. Some studies have indicated that limited proteolytic alteration of collagen occurs especially after long periods of aging.

Cystatin Muscle also contains a family of potent cysteine-type protease inhibitors collectively known as cystatins. These cystatins are found distributed throughout the muscle cell and in the living muscle are thought to modulate the activity of cysteine proteases. In postmortem muscle, the pH should favor the activity of many of the cathepsins and because of this it might be expected that myosin and possibly actin would be among the proteins degraded. However, there is little evidence of either myosin or actin degradation in postmortem muscle. The presence of cystatins may help explain why there is little evidence of cathepsin activity in postmortem muscle. Although there is some evidence that proteins like myosin and actin can be degraded when meat is stored at relatively high temperatures or for extremely long periods of time, myosin and actin are not degraded in the first week after slaughter under normal storage conditions. Therefore, the current evidence implicating the cathepsins in the tenderization of meat during the early stages of normal postmortem aging (when most tenderization occurs) is somewhat limited. Owing to this, in recent years, a much larger effort has been focused on the calpain enzyme system, a system that seems to degrade the same proteins that are degraded in postmortem muscle under normal meat storage conditions. Unlike the cathepsins, calpains degrade the majority of proteins into relatively few fragments, which is similar to what is seen in meat. It should

Calpain System The endogenous calpain system has been implicated as playing a major role in the proteolysis of muscle proteins under postmortem conditions. Some of the proteins that have been shown to be substrates of calpains include titin, nebulin, troponin-T, desmin, synemin, talin, and vinculin. Most of these proteins have structural roles within the muscle cell. Degradation of these proteins has been associated with a weakening of the muscle cell and the myofibrillar structure and with tenderness.

Calpain enzymes The calpain system is composed of several isoforms of tissuespecific and ubiquitous calcium-dependent cysteine proteases (calpains, EC 3.4.22.17), and their specific competitive inhibitor, calpastatin. The two best-characterized isoforms of calpains are the so-called ubiquitous forms m-calpain and m-calpain. They are referred to as ubiquitous because they are found in most tissues. These proteases are named m-calpain and m-calpain in reference to the amount of calcium they require for activation in vitro. m-Calpain requires between 3 and 50-mM calcium for half-maximal activity, whereas m-calpain requires between 0.4 and 0.8-mM calcium for half-maximal activity. Both m- and m-calpain are heterodimers composed of an 80- and a 28-kDa subunit. The 28-kDa subunit is identical in both m-calpain and m-calpain. The C-terminus of this subunit has four sets of amino acid sequences that predict calcium-binding EF hand structures; however, the exact function of this subunit is not known. The 80-kDa subunits of m- and m-calpains are similar, but are encoded for by different genes. The 80-kDa subunit is composed of four domains. Domain I, the N-terminal domain, has no sequence homology to any known polypeptide. Domain II is the catalytic domain and contains a cysteine residue as well as a histidine and asparagine residue that form a catalytic triad similar to that seen in other cysteine proteinases (including papain). Recent determination of the crystal structure of m-calpain has shown that in the absence of calcium, critical regions of the catalytic domain, domain II may be misaligned. The region of domain II (referred to as domain IIa) that contains the cysteine residue and the region of domain II that contains the critical histidine and aspargine residues (domain IIb) appear to be held slightly apart and rotated, potentially rendering the protease inactive. Release of specific structural constraints, possibly triggered by calcium, may play an important role in conferring activity to the enzyme. It has been speculated that conformational changes in domain I and III may play critical roles in calpain activation by their potential influence on the active site conformation in domain II. The

Tenderizing Mechanisms | Enzymatic

amino acid sequence of domain III is not homologous to any other known protein, but has two sets of sequences that predict EF hand Ca2 þ -binding sites. The crystal structure of mcalpain suggests that this domain resembles the C2-domain found in several Ca2 þ -regulated proteins like protein kinase C. Domain IV is a calmodulin-like domain that has four sets of sequences that predict EF hand Ca2 þ -binding sites. The protease m-calpain is active under in vitro conditions mimicking postmortem muscle pH, ionic strength, and temperature. Although the calpain enzymes are active under postmortem conditions, their level of activity is somewhat compromised by the low pH and high ionic strength conditions that develop within the meat during storage. During postmortem storage in beef and pork, m-calpain has been shown to become increasingly associated with the myofibril. It has been suggested that this myofibril-associated m-calpain may indeed be active. Although calcium is necessary for their activation, both mand m-calpain will also autolyze (selfdegrade) when incubated with calcium. Autolysis reduces the mass of the 80-kDa subunit of m-calpain to 76 kDa, and the mass of the 80-kDa subunit of m-calpain is reduced to 78 kDa. The 28-kDa subunit of both enzymes is reduced to 18 kDa. Brief autolysis also reduces the Ca2 þ concentration required for half-maximal activity of either enzyme. Extended autolysis leads to inactivation of the enzyme. Autolysis occurs under situations that allow activity, both in living cells and in postmortem muscle, but the significance of this is not clear. Both autolyzed and unautolyzed forms of the enzymes have been shown to have activity. However, the autolyzed form of m-calpain appears to be more hydrophobic and binds tightly to subcellular organelles, including myofibrils. The presence of the autolyzed form of m-calpain in postmortem tissue has been suggested to indicate that activity has occurred. One of the tissue-specific forms of calpain, often referred to as p94 or novel calpain-1, deserves mention. This musclespecific calpain isoform was the first tissue-specific calpain identified. The messenger ribonucleic acid for p94 in muscle has been reported to be as much as 10 times that of either m- or m-calpain. The p94 peptide appears to be a single polypeptide that has a structure similar to the large catalytic subunit of m- and m-calpain. It has a predicted molecular weight of 94 000 – slightly larger than the catalytic subunit of the ubiquitous calpains. This larger size is due to three unique regions: one in the N-terminus, one in the catalytic domain, and one at the interface of domains III and IV. Unlike m- and m-calpain, which are sarcoplasmic proteins, p94 is associated with the myofibrillar fraction. More specifically, p94 appears to be closely localized if not bound to the large myofibrillar protein titin. This calpain has proven to be very difficult to study as it autolyzes rapidly during conventional extraction procedures and so it has been very difficult to ascertain its role, if any, in proteolysis/tenderization.

calpastatin molecule may inhibit at least four calpain molecules. Calpastatin plays a major role in the regulation of the expression of calpain proteolytic activity. The amount of calcium required to allow half-maximal binding of calpastatin to calpains is generally lower than that required for half-maximal activity of the unautolyzed and autolyzed forms of m-calpain and for half-maximal activity of autolyzed m-calpain. Calpastatin binding is reversible as calcium chelators can cause calpastatin to dissociate from calpain. The level of inhibitory activity of calpastatin declines during postmortem aging (Figure 1). The level of inhibitory activity of calpastatin that remains at approximately 24 h after slaughter is associated with tenderness. Calpastatin is actually degraded in postmortem muscle and this rate of degradation is related to the rate at which it loses its ability to inhibit calpain. Both degradation of calpastatin and its loss of inhibitory activity are related to the rate of proteolysis and tenderization observed in meat. There is good evidence that calpains are at least partially responsible for the degradation of calpastatin. Currently, the conditions that promote calpain degradation of calpastatin in postmortem muscle have not been defined. Even though there has been much research done on the calpain system over the years, relatively little is known about its regulation. Certainly, the endogenous inhibitor of the calpains, calpastatin, is involved, but there is evidence to suggest that other mechanisms may also be important, particularly in meat. Environmental factors in the early postmortem muscle cell can influence calpain activity and inhibition of calpain by calpastatin. These can include factors like pH and ionic strength. Therefore, it is important to examine other mechanisms that may affect calpain activity to fully explain how calpain activity is regulated in meat. Alterations in pH or ionic strengths in early postmortem meat have the potential to cause conformational changes allowing for increased hydrophobicity. This increased hydrophobicity has been hypothesized to lead to aggregation of the enzyme. Likewise, pH/ionic

3.5 Calpastatin activity (units mg−1 heated protein)

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3 2.5 2 1.5 1 0.5 0

Calpastatin Calpastatin, the endogenous inhibitor of m- and m-calpain, has been found in all the tissues that contain calpains. Calpastatin in the skeletal muscle is a single polypeptide that contains within its structure four repeating domains that each has calpain inhibitory activity. Theoretically, then one

45 min

6h

24 h

Figure 1 Effect of aging time on calpastatin activity from porcine longissimus muscle. Data taken from Melody, J.L., Lonergan, S.M., Rowe, L.J., et al., 2004. Early postmortem biochemical factors influence tenderness and water-holding capacity of three porcine muscles. Journal of Animal Science 82, 1195–1205.

Tenderizing Mechanisms | Enzymatic strength changes may alter the conformation of substrate proteins and render them less susceptible to cleavage by m-calpain. A slightly accelerated pH decline has been shown to be associated with more rapid attainment of ultimate tenderness and more rapid proteolysis. However, a greatly exaggerated rate of pH decline, like the rapid pH decline that results in pale, soft, and exudative pork, seems to result in very limited aging potential. Hypothetically, a rapid pH decline would lead to an increased level of activity of catheptic enzymes and increased proteolysis; however, in most cases, this does not seem to occur. The product that has an exceptionally rapid pH decline has often been shown to also exhibit limited proteolysis of muscle proteins associated with tenderization. Low pH values have been shown to destabilize m-calpain and to promote more rapid autolysis and/or activation and subsequent inactivation in in vitro studies and may do the same in muscle tissue. Therefore, the rate of pH decline may play a very pivotal role in the attainment of ultimate tenderness.

Caspase Enzyme System Caspases are a family of enzymes that are involved in apoptosis, or programmed cells death. Cell death by apoptosis is characterized by a systematic and organized dismantling of a cell. Common hallmarks of apoptosis include shrinkage of the cell, cell membrane blebbing, chromatin condensation, damage to deoxyribonucleic acid, and the formation of apoptotic bodies without causing a generalized inflammatory response. Apoptosis is adenosine triphosphate (ATP) dependent, which may seem to be incongruous with postmortem tissue; however, in most postmortem muscle ATP can be produced for a period of time via anaerobic glycolysis, which may be different from the classical necrotic state. Necrosis is typically caused by a catastrophic loss of energy and is a passive process. It is accompanied by a loss of membrane integrity and swelling of organelles. Thus, in reality, as the loss of energy in the early postmortem cell is a gradual process, the argument could be made that early postmortem tissue resides in a ‘nether region’ between the two states of apoptosis and necrosis. The apoptotic process is choreographed by the caspases. Caspases are cysteine proteases that require their substrates to have aspartate residues. There are more than a 1000 substrates that have been identified for the caspases, and they include myofibrillar and cytoskeltetal proteins. Activation of caspases can be initiated by pathological events including ischemic/ hypoxic conditions. There are two general classes of caspases, initiatior caspases (caspases 8, 9, 10, and 12) and effector or executioner caspases (caspases 3, 6, and 7). Initiator caspases are activated when a stimulus for apoptotic events is received. Once they have been stimulated, these initiator caspases activate the executioner caspases by cleaving a linker that separates the small and large subunits of the catalytic domain. Once activated, the executioner caspases are responsible for the enzymatic cleavage of substrates that are ascribed to the caspase system. Since the early 2000s, caspases have been suggested to play a role in postomortem proteolysis related to tenderness. Many of the caspase substrates are proteins that have been shown to be at least partially degraded during the early postmortem

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period. These include (but are not limited to) actin, troponinT, desmin, and myosin light chains. The question of whether or not caspase enzymes or calpain enzymes are the predominant systems involved in early postmortem proteolysis has been hotly debated. It has proven difficult to rule out either system. Indeed, there is evidence that the two systems work together in the cell. For example, it has been shown that the calpain inhibitor, calpastatin, can be cleaved by caspases 1, 3, and 7, thereby directly influencing the activity of the calpain system. Thus, it may not be a question of which enzyme system is responsible for postmortem proteolysis, but rather, how do the two systems work together. For a more detailed discussion of relevant research on this topic, the reader is referred to the Further Reading section of this article.

Exogenous Enzymes In addition to allowing the endogenous enzymes to tenderize meat, exogenous enzymes, mostly of plant origin, have been used to augment the tenderization process. The most commonly used plant enzymes are papain (from papaya), bromelain (from pineapple), and ficin (from figs/ficus). More recently, actinidin (from kiwi) has been investigated, as has been zingibain (from ginger). Papain, bromelain, and ficin are all cysteine proteases and have a broad spectrum activity, cleaving a wide variety of bonds, thus degrading a large number of muscle proteins. These proteases are active in the pH range found in meat (papain, pH range 5.8–7; bromelian, pH range 5–7; and ficin, pH range 5–8). The ideal temperature range for these proteins is approximately 50–60 1C, making them maximally active on heating. Actinidin has a higher pH range than the aforementioned enzymes (ideal range is 7–10, but can have activity at pH 5–7) but the temperature range is similar. Zingibain is obtained from a crude extract of ginger. It has a maximum activity at pH 6–7 and a temperature of 60 1C. These plant-derived enzymes are very effective tenderizers. In addition to acting on myofibrillar proteins, most will also act very effectively on connective tissue proteins as well. In fact, one of the major challenges of using these enzymes is countering the effect of overtenderizing. However, continued research in the application of these enzymes is yielding better ways to utilize them. For further detailed information, the reader is referred to a review by Bekhit et al. (2013).

Conclusions On the basis of available data the major candidate to explain proteolysis of myofibrillar proteins and thus tenderization postrigor is the calpain protease system. The mode of action of the calpains is not yet fully defined and questions remain as to the role of m-calpain given the in vitro requirement for a Ca2 þ ion concentration exceeding that observed in postmortem muscle. The existence of the calpains in living muscle and other tissues is consistent with the involvement of these enzymes in tenderization (which reflects protein degradation) but suggests a mode of action more intricate than previously thought.

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An increase in ionic strength postmortem may assist degradation of proteins by enzymes and also lead to solubilization of proteins, but in itself is not the sole mechanism causing tenderization. Equally, changes in the binding of actomyosin (the complex of contractile proteins formed at rigor) or cleavage of myofibrillar proteins due to Ca2 þ ions do not offer plausible explanations for the mechanism that results in tenderization. It also appears that the cathepsin proteases are unlikely to have a role in early postmortem cleavage of proteins (proteolysis) and thus tenderization and this also applies to other enzyme groups such as the serine proteases, proteasomes and matrix metallopeptidases. Recent work on caspases has indicated that they may be worthy of further investigation, especially with respect to their interaction with the calpain system. The use of exogenous plant enzymes is a useful method to tenderize meat cuts beyond what can be achieved via postmortem aging alone and is a viable method to use particularly for cuts that have high amounts of connnective tissue.

See also: Carcass Composition, Muscle Structure, and Contraction. Conversion of Muscle to Meat: Aging; Glycogen; Glycolysis; Rigor Mortis, Cold, and Rigor Shortening. Tenderizing Mechanisms: Chemical; Mechanical

Further Reading Bekhit, A., Hopkins, D., Geesink, G., Bekhit, A., 2013. Exogenous proteases for meat tenderization. Critical Reviews in Food Science and Nutrition. doi:10.1080/ 10408398.2011.623247. Goll, D.E., Boehm, M.L., Geesink, G.H., Thompson V.F., 1997. What causes postmortem tenderization? In: Proceedings 50th Reciprocal Meat Conference, Iowa, pp. 60−67. Ames, IA: American Meat Science Association. Goll, D.E., Thompson, V.F., Li, H., Wei, W., Cong, J., 2003. The calpain system. Physiological Reviews 83, 731–801. Goll, D.E., Thompson, V.F., Taylor, R.G., Ouali, A., Chou, R.G., 1999. The calpain system in skeletal muscle. In: Wang, K.K., Yuen, R.W. (Eds.), Calpain: Pharmacology and Toxicology of Calcium-Dependent Protease. Philadelphia, PA: Taylor and Francis, Publishers, pp. 127–160. Hopkins, D.L., Thompson, J.M., 2001. Inhibition of protease activity 2. Degradation of myofibrillar proteins, myofibril examination and determination of free calcium levels. Meat Science 59, 99–209.

Hopkins, D.L., Thompson, J.M., 2001. The relationship between tenderness, proteolysis, muscle contraction and dissociation of actomyosin. Meat Science 57, 1–12. Hopkins, D.L., Thompson, J.M., 2002. Factors contributing to proteolysis and disruption of myofibrillar proteins and the impact of tenderisation in beef and sheep meat. Australian Journal of Agricultural Research 53, 149–166. Huff-Lonergan, E., Mitsuhashi, T., Beekman, D.D., Parrish, Jr., F.C., Olson, D.G., 1996. Proteolysis of specific muscle proteins by m-calpain at low pH and temperature is similar to degradation in postmortem muscle. Journal of Animal Science 74, 993–1008. Huff-Lonergan, E.J., Lonergan, S.M., 1999. Postmortem mechanisms of meat tenderization: The roles of the structural proteins and the calpain system. In: Xiong, Y.L., Ho, C.-T., Shahidi, F. (Eds.), Quality Attributes of Muscle Foods. New York, NY: Kluwer Academic/Plenum Publishers, pp. 229–251. Kemp, C.M., Parr, T., 2012. Advances in apoptotic mediated proteolysis in meat tenderisation. Meat Science 92, 252–259. doi:10.1016/j.meatsci.2012.03.013. Kemp, C.M., Sensky, P.L., Bardsley, R.G., Buttery, P.J., Parr, T., 2010. Tenderness − An enzymatic view. Meat Science 84, 248–256. Lamare, M., Taylor, R.G., Farout, L., Briand, Y., Briand, M., 2002. Changes in proteasome activity during postmortem aging of bovine muscle. Meat Science 61, 199–204. Moldovenu, T., Hosfield, C., Lim, D., et al., 2002. Ca2 þ switch aligns the active site of calpain. Cell 108, 649–660. Monin, G., Ouali, A., 1991. Muscle differentiation and meat quality. In: Lawrie, R. (Ed.) Developments in Meat Science, vol. 5. London: Elsevier Applied Science, pp. 89–157. Ouali, A., 1992. Proteolytic and physiochemical mechanisms involved in meat texture development. Biochimie 74, 251–265. Strobl, S., Fernandez-Catalan, C., Braun, M., et al., 2000. The crystal structure of calcium free human m-calpain suggests an electrostatic switch mechanism for activation by calcium. Proceedings of the National Academy of Sciences USA 97, 588–592. Takahashi, K., 1996. Structural weakening of skeletal muscle tissue during postmortem ageing of meat: The non-enzymatic mechanism of meat tenderization. Meat Science 43, s67–s80. Takahashi, K., 1999. Mechanism of meat tenderization during post-mortem ageing: Calcium theory. In: Proceedings 45th International Congress of Meat Science and Technology, pp. 230−235. Yokohama: Wageningen Academic Publishers. Uytterhaegen, L., Claeys, E., Demeyer, D., 1994. Effects of exogenous protease effectors on beef tenderness development and myofibrillar degradation and solubility. Journal of Animal Science 72, 1209–1223.

Relevant Website www.calpain.net Calpain Research Portal.

Mechanical DL Hopkins, NSW Department of Primary Industries, Cowra, NSW, Australia r 2014 Elsevier Ltd. All rights reserved. This article is a revision of the previous edition article by DL Hopkins, volume 3, pp 1355–1363, © 2004, Elsevier Ltd.

Glossary Aging The process of meat tenderization that occurs over time – it commences after rigor mortis. Contractile proteins Actin and myosin, which form the thin and thick filaments of skeletal muscle. These two proteins interact chemically (to form actomyosin), which gives muscle the ability to contract and relax. Associated with actin are the proteins troponin and tropomyosin. Costameres Connect Z-disks to the sarcolemma and are made up of proteins such as talin, vinculin, desmin, and dystrophin. Cytoskeletal proteins A set of filamentous structural proteins (includes actin, titin, nebulin, and desmin). Electrical stimulation The application of an electric current through a carcass postmortem that accelerates the rigor process. Myofibril Comprises contractile structural and regulatory proteins. The contractile protein is composed of myofilaments that are in turn made up of thin and thick filaments. Structural proteins include titin and nebulin. Titin is the largest protein in skeletal muscle (up to

Introduction Methods to reduce meat toughness by mechanical or physical means can be employed during either the prerigor or postrigor phase as muscle is converted to meat. The methods fall into two broad categories: those that prevent shortening during rigor or those that disrupt the meat structure either by physical or enzymatic means when applied some time after slaughter. In the former category, carcass-hanging methods, or excision of cuts combined with devices to restrict shortening, have been found to impact on tenderness levels. The mechanism behind these methods is essentially a restriction of the degree of actin and myosin overlap as muscle enters rigor and a reduction in fiber cross-sectional area. For the latter category of meat disruption, electrical stimulation, ultrasonic waves, blade tenderization, pressure treatment, and freeze–thawing have been investigated. These methods depend on one or more mechanisms: decreased actin and myosin overlap, physical damage to sarcomere and connective tissue structure, or altered rates of proteolysis. Although carcass-hanging methods have been found very effective for reducing the toughness of loin and hindquarter cuts and are generally cost-effective, they provide no benefit to forequarter cuts. The other methods provide the opportunity for more cuts to be improved, but the practicality and effectiveness is in some cases questionable. Inevitably, any method that reduces the density of muscle fibers in a unit area or

Encyclopedia of Meat Sciences, Volume 3

3700 kDa) and provides the elasticity to the sarcomere. The regulatory proteins include troponin and tropomyosin. Proteolysis The degradation of proteins into smaller subunits that occurs with aging, but also in turnover of living muscle. Rigor A term for individual muscle fibers that have been depleted of adenosine triphosphate and in which the actomyosin bond has formed. Rigor mortis A term describing muscle stiffening after all muscle fibers enter rigor. Sarcomere The basic unit of skeletal muscle defined by the distance between two Z-disks. Z-disks are dense protein structures to which the contractile protein actin is attached along with proteins such as titin and nebulin. Z-disks are the anchor points for the contractile proteins that allow contraction and relaxation. Shear force The force (N) applied to a standardized piece of cooked meat to shear it. Shortening A process that occurs when prerigor muscle is cooled below 10 °C. It also occurs as muscles enter rigor at high temperatures (rigor shortening).

causes disruption of sarcomere structure will lead to a reduction in the toughness of cooked meat. Shear force is an objective instrumental measure of tenderness, where high shear values indicate increasingly unacceptable meat (tougher). Tenderness can also be assessed by sensory evaluation, where high numbers indicate greater levels of satisfaction (less tough).

Carcass Methods Tenderstretching The decline postrigor in shear force from a peak attained during rigor is illustrated in Figure 1. Numerous studies have shown that temperature conditions prerigor dramatically influence the level which the peak reaches. Prerigor methods that physically prevent a large rise in the peak shear force (indicated by arrows) will confer an immediate postrigor advantage in tenderness. Suspension of carcasses by the obturator foramen or aitchbone so that the back leg falls into the walking position (Figure 2) was given the name tenderstretch. Researchers in the US first investigated this method and Australian researchers conducted extensive follow-up research. The technique places tension on the hind leg and loin muscles and physically prevents them shortening (i.e., reduces the overlap of actin and myosin).

doi:10.1016/B978-0-12-384731-7.00092-1

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Shear force (N)

Shear force vs. time

Table 1 Warner–Bratzler shear values (N) for muscles measured at 2–3 days postmortem obtained from sides of beef hung by either the Achilles tendon or aitchbone

94 84 74 64 54 44 34 24 14 4

Muscle

0

10

20

30

40

50

60

70

80

Time (h) Figure 1 Time course changes in shear force of ovine longissimus during postmortem storage. Maximum contraction occurs somewhere between the arrows as the muscle enters rigor. Data from Wheeler, T.L., Koohmaraie, M., 1994. Prerigor and postrigor changes in tenderness of ovine longissimus muscle. Journal of Animal Science 72, 1232–1238.

Semimembranosus Gluteus medius Longissimus Vastus lateralis Biceps femoris Semitendinosus Infraspinatus Psoas major

Method of suspension Achilles tendon

Aitchbone

82.4 78.5 107.9 86.3 63.7 59.8 62.3 35.3

50.0 39.2 55.9 53.0 65.7 58.8 58.8 49.0

Source: Adapted with permission from Bouton, P.E., Fisher, A.L., Harris, P.V., Baxter, R.I., 1973. A comparison of the effects of some post-slaughter treatments on the tenderness of beef. Journal of Food Technology 8, 39−49.

The improvement in tenderness is so dramatic that the need for prolonged aging is virtually eliminated; in addition, the variation in tenderness along the loin muscle is reduced. Commercial adoption of this technique has seen resurgence as processors have developed ways to handle and store tenderstretched carcasses, such as adopting methods to rehang carcasses from the Achilles tendon after attainment of rigor and streamlining the processing of carcass movement and boning. Pelvic suspension (or tenderstretch) alone has not been patented. Cargill Incorporated in the US have patented pelvic suspension as part of a wider meat tenderization system incorporating separating vertebrae (a variant of the tendercut technique below), pelvic suspension, electrical stimulation, and immediate subsequent Achilles suspension. In this methodology pelvic suspension is used for less than 10 min, preferably less than 2 min, restricting muscle contraction only as the muscles approach rigor. No claims are made as to the efficacy of this process. Figure 2 The carcass is suspended by the aitchbone so that the back leg drops and the backbone straightens and maximum tension is placed on these muscles. Photograph courtesy of J.M. Thompson.

The extent of the improvement across a range of muscles is clearly demonstrated in Table 1 for cuts taken from beef carcasses. Shear force was significantly reduced by tenderstretch in the majority of hindquarter muscles. The notable exceptions to this trend were the m. biceps femoris and m. semitendinosus. This latter muscle is stretched in Achilles-hung sides and in the case of the m. psoas major it actually shortens in tenderstretched carcasses. By weighting the hind legs, a further reduction in shear force (20%) can be achieved, particularly in the loin muscle; it has recently been shown that this technique causes significant disruption of the sarcomere, with distortion of the Z-disk and actual tearing of the filaments (Figure 3). It is this disruption and a decreased overlap of actin and myosin that results in the dramatic reduction in shear force.

Tendercut An alternative method to tenderstretch has been developed called ‘tendercut.’ This method offers an advantage in carcass handling because the leg is still hung by the Achilles tendon. The tendercut process was initiated by Claus and Marriott in 1991 (Virginia Polytechnic Institute and State University, USA). The tendercut process applies tension on muscles by breaking the vertebrae and pelvic bones in the hot carcass. This process involves sawing the vertebral column at the 12th/13th rib junction and/or the ischium at the rump/butt junction (Figure 4). In addition to breaking the vertebrae at the 12th/ 13th rib junction, all tissues surrounding the loin are cut, such that only a dorsal component is holding the forequarter to the hindquarter. The adipose tissue dorsal to the longissimus muscle is also cut to expose the epimysium and this cut is then continued around the medial side of the loin muscle and the m. multifidus dorsi is completely severed. Intercostal connective tissue and muscle are then cut between the 12th/ 13th costal bones. This latter cut is extended approximately

Tenderizing Mechanisms | Mechanical

(a)

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(b)

Figure 3 Images of ovine longissimus captured with an electron microscope (original magnification×10 000) from (a) a carcass tenderstretched and weighted with 2 kg weights and (b) a sample from a normally hung (by Achilles tendon) carcass shown for comparison. White bars¼ 500 nm. Reproduced from Hopkins, D.L., Garlick, P.R., Thompson, J.M., 2000. The effect on the sarcomere structure of super tenderstretching. AsianAustralasian Journal of Animal Science 13 (Supplement C), 233, with permission of the Asian-Australasian Journal of Animal Science.

of either cuts or a single cut, in which case fewer muscles will be affected. Compared to tenderstretching, the tendercut process overcomes the need for additional chiller space and avoids the need to train boners on new cutting lines, but is much more difficult to carry out on a processing line. Based on published evidence it also appears that this method does not reduce the shear force of loin and leg muscles to the same extent as tenderstretching. However, like the former method, tendercut does reduce the proportion of unacceptable loin steaks when tested by consumers, and in one study the proportion of unacceptable scores for overall tenderness was reduced from 19% to 2.5%. The magnitude of the gain achieved within either of these hanging methods will be influenced by the chilling regime, with a lower improvement expected under slow chilling conditions.

Electrical Stimulation

Figure 4 A photograph showing a severed vertebral column as used as part of the tendercut method. Photograph courtesy of J.R. Claus.

12 cm from the lateral edge of the loin muscle. The second cut severs the ischium at the site used to separate the butt/rump joints, the junction between the 4th/5th sacral vertebrae and connective tissues. The fillet muscle must be freed from its attachment and deflected forward during sawing. In addition, care must be taken while sawing the ischium to minimize damage to the rump cut. The technique can be applied by use

Accelerated fall in postmortem pH is one of the main outcomes of electrical stimulation; however, there is some evidence that stimulation does cause physical disruption of muscle. Histological images of stimulated muscle at times show the appearance of contractile bands containing predominantly stretched, ill-defined, and disrupted sarcomeres. Contracture bands are not a direct consequence of electrical current passing through the muscle, but are rather due to the supercontracture caused through localized excessive release of calcium ions from the sarcoplasmic reticulum. This suggests that they are a consequence of abnormal, perhaps localized, calcium release from the sarcoplasmic reticulum through a

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tetanic contracture. This extra calcium could lead to tenderization through activation of enzymes such as the calpains, but any reduction in toughness could alternatively be due to a purely physical effect via a reduction in fiber density in a unit area. It has been shown quantitatively in beef m. longissimus that sarcomeres adjacent to contracture bands have a higher frequency of I-band fracture. Ultrastructural changes are fiber type-specific and depend on the duration and effectiveness of the applied stimulation, the current frequency, and the interaction between current frequency and voltage. If the time interval between successive stimuli is more than approximately 0.25 s, the muscle tetanic shortening is reversible. However, when a higher frequency of current is applied, muscle may not have enough time for relaxation between succeeding twitches, and irreversible contracture bands are formed. At present, it is not possible to determine how much improvement in tenderness as a result of electrical stimulation stems from a reduction in fiber density in unit area as a consequence of contracture as opposed to increased activity of enzymes due to spikes in the concentration of free cytoplasmic Ca2+. Quantitative studies examining ultrastructural alteration, shortening, and proteolysis are necessary under the same experimental conditions to clarify the contribution of these variables to improvements in tenderness. A combination of stimulation and tenderstretching has not been found to confer a significant additive advantage over separate treatment of muscles with either method.

Cut Methods It has been demonstrated that if prerigor muscle can be excised from the carcass and held to prevent shortening (e.g., by wrapping), then this can provide a potentially economical way to speed up processing and at the same time minimize toughening. This does require chilling at a temperature that minimizes rigor shortening. Several different approaches have been developed in recent years.

Pi-Vac Elasto-Pack System® The Pi-Vac Elasto-Pack System® is a method of tightly wrapping hot-boned muscles in an elastic wrapping material prerigor to prevent shortening and toughening of the meat. The system uses a highly flexible packaging sleeve, which is expanded using a partial vacuum to allow the meat to be inserted. Once the vacuum is turned off the flexible packaging retracts to its normal dimensions. This exerts longitudinal forces on the meat, preventing the contraction of the muscle. Almost all of the oxygen is also forced out of the packaging. The subsequent bound meat product has been labeled TenderBound. This technology can come in three different sizes (Figure 5) and some commercialization of this approach has occurred in Europe. By adopting the concept of super tenderstretching by using weights and applying it to hot-boned beef muscle it has been shown that tenderness could be achieved equivalent to that realized with the Pi-Vac Elasto Pack System®. Additionally, the Pi-Vac Elasto Pack System® produced meat with the lowest variation, indicating that this method

Figure 5 The Pi-Vac Elasto-Pack System showing three different sizes. The middle size shows the plastic film that is used inside the machine. Photograph courtesy of Hans-Werner Meixner.

does something different to meat structure, but there have been few published studies outlining the benefits or otherwise of the technology.

SmartStretch™ This technology was designed to apply air pressure/vacuum to excised individual prerigor muscles to stretch the muscle into an even form and package it so as to retain the form. The technology was patented by Meat and Wool New Zealand Limited and Meat and Livestock Australia Limited as the ‘Boa’ and was subsequently registered as SmartStretch™. As with all stretching systems the aim was to either stretch sarcomeres or prevent the contraction of sarcomeres during rigor, with some resultant tenderness benefits. The machine's operation is based on an externally ribbed flexible sleeve surrounded by inflatable bladders that are housed within an airtight chamber that air can be pumped into or out of. Air is pumped out of the chamber to create negative pressure, which causes the sleeve to expand, allowing the meat to be inserted. Air is then pumped into the inflatable bladders causing the meat to be compressed by force perpendicular to the direction of the muscle fibers. This also applies peristaltic action, moving the meat toward the same end of the sleeve that it was inserted into. Positive pressure is then applied to the exterior of the sleeve by pumping air into the chamber, forcing the meat upwards and into packaging as shown in Figure 6. As with the Pi-Vac system the application of SmartStretch™ is for hot-boned muscles and work has been conducted in Australia, mostly with sheep and beef meat from old animals. Initial experiments with sheep meat were promising. A 24% increase in m. semimembranosus length resulted in shear force reductions of 46% at 0 days aging and 38% at 5 days aging and was matched with a significant increase in sarcomere length. A further study examined the effect when the muscles were stretched as part of a whole sheep meat hind leg. A 14% increase in leg length resulted in a shear force reduction in the m. semimembranosus of just 16% and of 18.4% in the m. biceps femoris at 0 days aging and no significant difference at 5 days aging. Significant increases were found in sarcomere length

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Figure 6 Stretched beef being ejected from the flexible sleeve into the packaging. Photograph courtesy of D.L. Hopkins.

following stretching. However, a number of the studies conducted on beef m. semimembranosus, m. longissimus lumborum, and rostbiff (mainly m. gluteus medius) were inconclusive as to the SmartStretch™ system's impact on beef tenderness. Increasing stretch in the m. semimembranosus from 34% to 52% had no impact on shear force, but this was proposed to reflect the fact that once a basal level of stretch was achieved further stretching would not have an effect. A 21% increase in length of the m. semimembranosus and rostbiff also had no significant impact on shear force or on sensory results, although the shear force values were so high that tasters could not discriminate between the tough and the extremely tough product. A reduction in the variability in shear force was found. By contrast, when younger cattle (maximum dentition score of 2) were used the results showed a significant improvement in hot-boned meat tenderness by the use of SmartStretch™. Initial work in beef comparing SmartStretch™ to Tenderstretch, ‘Superstretch’ (Tenderstretch plus a pulley system to pull the hindlimb toward the forequarter), and Achilles suspension showed similar tenderness improvements in the m. longissimus lumborum resulting from all three stretching treatments in prime cattle. The results for two stretching treatments are shown in Figure 7. Follow-up work in young cattle showed that tenderness of the rostbiff (m. gluteus medius), as reflected in reduced shear force measurement, was significantly improved in 0 day aged stretched samples over the unstretched hot-boned control. After 8 days aging there was no longer a difference in the tenderness between stretch treatments. Sarcomere length was significantly increased by stretching in both studies.

Blade Tenderization The physical disruption of muscle structure must reduce the density of cooked meat fibers in unit area and therefore impart an improvement in tenderness. Blade tenderization is used for this purpose commercially. Commonly, cuts of meat are placed on a conveyor and pass through a machine that consists

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Figure 7 Effect of hanging/stretching method and aging on , Achilles-hung carcasses; , Tenderstretch-hung tenderness. carcasses; and , SmartStretch™-treated meat. Adapted from Geesink, G., Thompson, J., 2008. Utilising the ‘Boa’ stretching technology to improve the quality of hot boned striploins. Report No. RE-221941, Armidale, NSW, Australia: University of New England, School of Environmental and Rural Science. Available at: www. redmeatinnovation.com.au/innovation-areas/eating-quality/products/ smartstretch/validation-trials (accessed 06.09.12).

of spear-shaped blades arranged on a mounted head. Blade density can be greater than one blade per 1 cm2 of head and the pattern of cut can also be varied. Other types of devices, which combine a large screw and pressure to extrude the meat through a slit, also cause significant disruption and reduce toughness (by fracturing fibers). Repeated treatment of cuts by blade tenderization may confer some additional benefit, but the gain is marginal and good sanitation is required to avoid bacterial contamination between cuts. Commercial blade tenderization devices are often used for infusing solutions into meat and these solutions may contribute to tenderization. Histological examination of treated meat samples shows that the muscle fibers are torn and fragmented by the blade, as is connective tissue, but areas between points of blade penetration will be unaffected. Despite this localized effect, the density of blades compensates and this technique confers significant improvement to a range of cuts (see Figure 8), but particularly for some of the toughest cuts of the hind leg such as the topside (m. semimembranosus). In contrast, there is much less benefit for inherently tender cuts such as the rib-eye (m. longissimus thoracis).

Ultrasonic Waves Sound waves travel through material at different speeds and impart energy to the transmission material, which has the potential to cause physical disruption, particularly when the wavelength is similar to the size of structural units of the material. Both frequency and wavelength can be varied, but few studies using meat have focused on high-frequency (41 MHz) ultrasonic waves, with more attention on lowfrequency waves. Theoretically, disruption of muscle cell integrity could also lead to a leakage of Ca2+ from the sarcoplasmic reticulum and release of cathepsins from the lysosomes, hastening the onset of enzyme activity. Indeed, there is a suggestion that prerigor treatment of m. semimembranosus from beef with ultrasound at 2.6 MHz

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Cut Figure 8 Impact of mechanical tenderization on the tenderness of cuts of meat from beef carcasses. Modified with permission from Jeremiah, L.E., Gibson, L.L., Cunningham, B., 1999. The influence of mechanical tenderization on the palatability of certain bovine muscles. Food Research International 32, 585–591.

(intensity 10 W cm–2) can elevate the levels of free cytosolic Ca2+ and does lead to an increase in sarcomere length (~10%). Despite this effect, no clear advantage in reducing toughness has been reported and this applies equally to low-frequency, low-intensity ultrasound. The size of meat sections and the use of muscles with high connective tissue content (e.g., m. semitendinosus) could be some of the reasons for the apparent lack of effect of ultrasound on toughness. From a practical perspective, the transmission of sound waves causes a dissipation of energy and this results in a rise in material temperature. As a consequence, a number of studies have submerged the meat in cold water, which would potentially limit commercial adoption. It would appear that the use of ultrasound to increase tenderization rate currently has limited applicability, although it may be feasible to integrate its use with hot-boning operations in which meat is passed through a water-cooling submersion system, at which time the meat could be exposed to a barrage of ultrasonic waves.

Hydrodynamic Pressure One of the most novel techniques that have been developed to reduce toughness is the Hydrodyne process. In this process a small amount of explosive is used to generate a shock wave that travels through water in fractions of a millisecond. The idea was proposed by John Long, a mechanical engineer, who developed the concept further with the help of Morse Solomon (USDA, Beltsville, MD, USA), and Eric Staton who had experience in the use of explosives. The process requires that the meat be held within a container and surrounded by water; because meat has a high content of water, the shock waves travel through the meat. When the meat is held inside a metal or plastic container, the shock waves are reflected from the walls and intersect; this increases the pressure, leading to physical disruption of the encapsulated meat. Electron micrographs of treated meat show I-band proteins totally separated from the Z-disk and fractures

at the A-band/I-band junction, and thus the increase in tenderness would appear to be mediated through physical degradation of muscle structure in particular myofibrillar proteins. As for any method that results in such a degree of disruption, it is also feasible that cellular structure is damaged, leading to the release of protein-degrading enzymes (i.e., calpains or cathepsins) or activators of these enzymes such as Ca2+, hastening proteolysis. A somewhat related method is to apply hydrostatic pressure to meat; in this case it is the pressure of a liquid on immersed meat that results in a reduction in toughness (see next section). Early development of the Hydrodyne process showed that the reduction in toughness was influenced by the amount of explosive that was used, the number of detonations, and whether the meat was fresh or frozen. The process was more effective for fresh meat and two detonations using 50 g of explosive were as effective as one detonation using 100 g of explosive. The effect on toughness, as measured by shear force, is dramatic (Figure 9), with improvements of up to 70%. The magnitude of improvement is sufficient to make even cuts high in connective tissue acceptable for table meat (e.g., topside, Figure 9). In the case of the data shown in Figure 9, the cuts were excised from the carcass 1.5 h after death and stored for 1 day at 2–4 °C, explaining the high shear values for control cuts, indicative of cold-induced shortening, and suggesting that the Hydrodyne process was able to overcome this toughening effect. As for many techniques, the magnitude of the effect is influenced by the toughness of control samples and when it was applied to relatively tender pork loins the improvement was only 17%, but the evidence indicates that this technique will also reduce the variation in shear force. The process has not yet been successfully commercialized and the concept is still under development. A current prototype (Figure 10) can tenderize 270 kg of meat at once. The unit consists of a 3.2-ton steel tank filled with water, which is covered with a 2.3-ton steel dome (see photograph below), 2.7 m in diameter. Cuts of meat, encased in water and pressure-resistant wrapping, are placed into the tank, which is 3 m

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Cut Figure 9 Impact of Hydrodyne treatment on the shear force (N) of beef cuts (8 samples per muscle) after 1 day of aging, and treatment of the cuts after freezing and subsequent thawing. Modified from Solomon, M.B., Long, J.B., Eastridge, J.S., 1997. The Hydrodyne: A new process to improve beef tenderness. Journal of Animal Science 75, 1534–1537.

continues with a focus on variables such as container type (metal vs. plastic), the material used to pack the meat, location of the explosive (distance from meat), and the type of explosive. Future models may be based on generation of shock waves with an alternative to the use of explosives.

Hydrostatic Pressure

Figure 10 A large-scale Hydrodyne unit (1060 l) showing the inner section where the encased meat and surrounding water are held, with the large dome in the background. Photograph courtesy of M.B. Solomon.

in the ground, and an explosive charge is detonated in the water less than a meter from the meat. The tank's dome holds in water that is forced upwards. Refinement of the process

Subjecting meat to high pressure via a surrounding liquid has been adopted in countries such as Japan, Australia, and the US in order to extend shelf-life and reduce bacterial counts. The technique is combined with heat treatment (e.g., to 60 °C) while the muscle is under pressure. The method has a high capital cost, limiting adoption, but can also be used to decrease the toughness of meat. First reports on the technique were published in the 1970 s after research in Australia. The technique can be applied to both prerigor and postrigor muscle and, similar to hydrodynamic shock waves, will cause a disruption of muscle structure that is confirmed in electron microscopy studies. Prerigor meat exhibits accelerated glycolysis under pressure/heat treatment and this treatment leads to a significant reduction in shear force (Figure 11). In this case, the shear force values of the m. longissimus from control carcasses indicate cold-induced shortening, yet the negative effects of prerigor excision of muscles through shortening can be overcome by pressure treatment. Hydrostatic pressure can cause the degradation of specific myofibrillar proteins such as titin and depolymerization of actin, but also appears to decrease the contribution that connective tissue makes to overall toughness. At 100 MPa, structures such as lysosomes are observed to alter shape and, as the pressure rises, disruption of membranes occurs. This disruption leads to the release of catheptic enzymes into the cytoplasm and absorption onto myofibrils. However, given the lack of evidence that these enzymes play a significant role in tenderization, these seem unlikely to contribute to the

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Cut Figure 11 Effect of prerigor pressurization (∼100 MPa) at 35 °C for 2 min on the shear force of beef cuts. Modified from MacFarlane, J.J., 1973. Prerigor pressurization of muscle: Effects on pH, shear value and taste panel assessment. Journal of Food Science 38, 294–298.

beneficial effect that arises from this technique. A greater reduction in calpastatin activity than in μ-calpain at pressures above 100 MPa suggests that this enzyme could contribute to the degradation of muscle structure mediated through a rise in the level of free Ca2+, although at pressures above 200 MPa μ-calpain appears to be inactivated. Detailed research examining the effect of this type of pressure on enzyme activity, physical changes in muscle structure, and the impact on tenderness (i.e., shear force) remains to be conducted before the exact mechanism is established. A variation on this approach is to combine pressure treatment with freezing. This involves cooling samples under pressure (200 MPa) to –20 °C and releasing pressure to reach equivalence with atmospheric pressure, causing supercooling of the sample.

Freeze–Thaw Freezing muscle (i.e., at –20 °C) leads to shrinkage of muscle fibers mediated through a dehydration of cells and significantly increases the fragmentation of myofibrils. The extent of these effects will be influenced by the size of samples and the freezing rate, which impact on thermal gradients within the sample. Reductions of more than 20% in shear force values have been observed in muscle after freezing and thawing during the early stages of aging compared to muscle tested from the fresh state after the same period of aging. The effect will not be observed in ‘aged’ meat. There are likely to be several explanations for this reduction, which may well interact in a synergistic manner: proteolysis during the thawing phase, physical damage due to the freeze–thaw cycle, or diminished activity of enzyme inhibitors such as calpastatin.

See also: Chemical and Physical Characteristics of Meat: Palatability; Protein Functionality. Connective Tissue: Structure,

Function, and Influence on Meat Quality. Conversion of Muscle to Meat: Aging; Color and Texture Deviations; Glycolysis. Cutting and Boning: Hot Boning of Meat. Electrical Stimulation. Muscle Fiber Types and Meat Quality. Tenderizing Mechanisms: Enzymatic

Further Reading Bouton, P.E., Fisher, A.L., Harris, P.V., Baxter, R.I., 1973. A comparison of the effects of some post-slaughter treatments on the tenderness of beef. Journal of Food Technology 8, 39–49. Claus, J.R., Wang, H.J., Marriott, N.G., 1997. Prerigor carcass muscle stretching effects on tenderness of grain-fed beef under commercial conditions. Journal of Food Science 62, 1231–1234. Devine, C.E., Wahlgren, N.M., Tornberg, E., 1999. Effect of rigor temperature on muscle shortening and tenderisation of restrained and unrestrained beef m longissimus thoracics et lumborum. Meat Science 51, 61–72. Duckett, S.K., Klein, T.A., Leckie, R.K., et al., 1998. Effect of freezing on calpastatin activity and tenderness of callipyge lamb. Journal of Animal Science 76, 1869–1874. Ferrier, G.R., Hopkins, D.L., 1997. Tenderness of meat cooked from fresh, frozen and thawed states. Proceedings 43rd International Congress of Meat Science and Technology, Auckland, pp. 560−561. Geesink, G., Thompson, J., 2008. Utilising the ‘Boa’ stretching technology to improve the quality of hot boned striploins. Report No. RE-221941, Armidale, NSW, Australia: University of New England, School of Environmental and Rural Science. Available at: www.redmeatinnovation.com.au/ innovation-areas/eating-quality/products/smartstretch/validation-trials (accessed 06.09.12). Got, F., Culioli, J., Berge, P., et al., 1999. Effects of high-intensity high-frequency ultrasound on ageing rate, ultrastructure and some physico-chemical properties of beef. Meat Science 51, 35–42. Homma, N., Ikeuchi, Y., Suzuki, A., 1995. Levels of calpain and calpastatin in meat subjected to high pressure. Meat Science 41, 251–260. Hopkins, D.L., Garlick, P.R., Thompson, J.M., 2000. The effect on the sarcomere structure of super tenderstretching. Asian-Australasian Journal of Animal Science 13 (Supplement C), 233. Hwang, I.H., Devine, C.E., Hopkins, D.L., 2003. The biochemical and physical effects of electrical stimulation on beef and sheep meat tenderness − a review. Meat Science 65, 677–691.

Tenderizing Mechanisms | Mechanical Jeremiah, L.E., Gibson, L.L., Cunningham, B., 1999. The influence of mechanical tenderization on the palatability of certain bovine muscles. Food Research International 32, 585–591. MacFarlane, J.J., 1973. Pre-rigor pressurization of muscle: Effects on pH, shear value and taste panel assessment. Journal of Food Science 38, 294–298. O'Sullivan, A., Korzeniowska, M., White, A., Troy, D.J., 2003. Using a novel intervention technique to reduce the variability and improve tenderness of beef longissimus dorsi. Proceedings 49th International Congress of Meat Science and Technology, Campinas, Brazil, pp. 513−514. Petersohn, R.A., Topel, D.G., Walker, H.W., Draft, A.A., Rust, R.E., 1979. Storage stability, palatability and histological characteristics of mechanically tenderized beef steaks. Journal of Food Science 44, 1606–1611. Sakata, R., Oshida, T., Morita, H., Nagata, Y., 1995. Physico-chemical and processing quality of porcine m. longissimus dorsi frozen at different temperatures. Meat Science 39, 277–284. Solomon, M.B., Long, J.B., Eastridge, J.S., 1997. The Hydrodyne: A new process to improve beef tenderness. Journal of Animal Science 75, 1534–1537. Toohey, E.S., van de Ven, R., Thompson, J.M., Geesink, G.H., Hopkins, D.L., 2012. SmartStretch™ Technology. V. The impact of SmartStretch™ technology on beef topsides (m. semimembranosus) meat quality traits under commercial processing conditions. Meat Science 92, 24–29.

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Taylor, J.M., Hopkins, D.L., 2011. Patents for stretching and shaping meats. Recent Patents on Food, Nutrition & Agriculture 3, 91–101. Taylor, J.M., Toohey, E.S., van de Ven, R., Hopkins, D.L., 2012. SmartStretch™ technology. IV. The impact on the meat quality of hot-boned beef rostbiff (m gluteus medius). Meat Science 91, 527–532. Wheeler, T.L., Koohmaraie, M., 1994. Prerigor and postrigor changes in tenderness of ovine longissimus muscle. Journal of Animal Science 72, 1232–1238.

Relevant Website www.mla.com.au/off-farm Meat & Livestock Australia.

TENDERNESS MEASUREMENT

RW Purchas, Massey University, Palmerston North, New Zealand r 2014 Elsevier Ltd. All rights reserved.

Glossary Intrinsic determinant A feature within the meat that plays a role in determining the level of specific meat quality characteristic such as tenderness. Proteolysis The chemical reaction that results in breakdown of proteins into smaller parts as peptides or individual amino acids.

Introduction Meat tenderness appears at first glance to be simply a measure of the biting effort required. Unfortunately, however, this is an oversimplification as careful mechanical measures of such forces seldom account for more than approximately 60% of the variation in tenderness as assessed by trained panels of people. This is despite the fact that many mechanical devices have been developed, and a number of these are widely used in studies of factors affecting meat tenderness. The inconsistencies between mechanical and sensory assessments of tenderness are at least partly because a consumer′s sensory perception of meat tenderness is often influenced by

Sarcomere length The distance between adjacent Z discs in a muscle fiber or fibril. Shear force The force required to shear or cut through a piece of meat, that is used as an index of meat tenderness. Tenderometer An instrument designed to measure the tenderness of meat.

components other than the dominant one of the simple biting force required. In this article, approaches to the measurement of meat tenderness are outlined, and some terms used to describe tenderness are described first. The main characteristics within meat that play a role in determining its tenderness, the so-called ‘intrinsic determinants’ of tenderness, are discussed because they influence the extent to which a particular measurement method will be appropriate for a specific situation. Approaches to the measurement of meat tenderness outlined here include primarily the use of mechanical devices such as the Warner– Bratzler shear device, but also the use of descriptive/trained and consumer sensory panels, and some other laboratory methods.

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Figure 1 A diagrammatic illustration of how the relationship between sensory tenderness and mechanical measures of tenderness differ depending on whether the sensory panelists score on an acceptability scale (blue solid line), as for a consumer panel, in which case extremely tender meat may be less acceptable, or a level-of-tenderness scale (red dashed line) as used by a trained panel. Note that the closeness of the relationship between mechanical measures and sensory assessments of tenderness is not generally as close as implied by these lines.

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Table 1 Some intrinsic determinants of meat tenderness. An intrinsic determinant is a structural or metabolic characteristic within the meat that can be responsible for differences in meat tenderness. The suitability of methods for measuring differences in tenderness for any group of meat samples will depend on which of these or other determinants are responsible for the differences Intrinsic determinant

Relationship with tenderness

Relative importance and situations where it might be particularly important

1. Concentration of connective tissue. This tissue Other things being equal, meat containing more Of medium importance. More important for consists primarily of the fibrous protein connective tissue will be less tender, but this comparisons (1) between different muscles, (2) between meat samples from older animals collagen but will also include some elastin and will depend on the nature of the connective or between samples from animals varying other substances. tissue and the cooking conditions. widely in age, and (3) when cooking conditions have been mild (i.e., most collagen will not be not dissolved when final internal temperatures are less than approximately 60 °C). 2. The extent of cross-linking between peptide Other things being equal, meat containing This is an important source of variation in chains within collagen molecules in meat. collagen with less cross-links will be more tenderness if samples vary widely in the level of tender because such collagen will dissolve to cross-linking, as might be expected if they are form gelatin faster and at lower temperatures. from animals varying widely in age (crosslinking increases with increasing age). It is also more important for fast cooking methods such as frying because the solubilization of collagen is to some extent time dependent. The type of cross-links may influence the extent to which tenderness is affected. 3. The ultimate pH (pHult) of the meat, as An important determinant of tenderness in some Other things being equal, an increase in pHult from approximately 5.5 (the normal pHult for situations where the variability of pHult is high. determined primarily by the amount of lactic acid present, which, in turn, is a function of the meat from a well-fed and unstressed animal) to In many situations it is of low importance 6.1 (the peak of toughness, 5.8–6.1) will often because there is little variation in pHult between glycogen levels at the time of slaughter. lead to tougher meat. With further increases animals. from approximately 6.2 to 7.0, however, the meat becomes tenderer with other deficiencies. Very important as a determinant of tenderness 4. The extent to which muscle is contracted when Other things being equal, a greater degree of under cold shortening conditions when low it sets in rigor mortis, as commonly assessed contraction (shorter sarcomere lengths) will be by the average sarcomere length. associated with tougher meat. This relationship temperatures prerigor induce muscle is not linear and muscle shortened by more than contraction. Thaw shortening of meat frozen approximately 40% of its resting length will before the onset of rigor mortis can also lead to actually be tenderer due to structural damage. very tough meat. If shortening is prevented in some way, this is not an important determinant. An important determinant of the extent to which 5. The extent to which certain proteins in meat are Other things being equal, a greater degree of tenderness improves with aging of meat at protein breakdown is associated with tenderer broken down postmortem through the action of proteolytic enzymes such as the calpains meat, but the extent of this effect will depend temperatures above freezing. It also accounts on the specific proteins that are cleaved. for some genetic differences in tenderness and cathepsins. through varying levels of either proteolytic enzymes (e.g., the calpains) and/or their inhibitors (e.g., calpastatin). 6. The concentration of intramuscular fat Other things being equal, more highly marbled This determinant seldom accounts for more than (marbling) in muscle. Levels vary from less meat will be somewhat tenderer. The reasons 10% of the variation in tenderness but is more than 2% in many lean meat products through for this are unclear but probably include the fact likely to be more important when there is a approximately 3–4% when the marbling first that the meat will tend to be more juicy, muscle wide variation in marbling levels. becomes clearly visible, up to levels of more fibers and connective tissue are diluted by fat, than 30% in very heavily marbled products. and a reduced likelihood of prerigor shortening.

Descriptive Terms and Scales When meat tenderness is measured by a sensory panel, higher values usually indicate more tender meat either on an acceptability (hedonic) scale or on a level of tenderness scale. However, these two scales do not necessarily correspond, as, although a lower acceptability of tenderness is usually due to a greater toughness, this is not always the case as meat can also be less acceptable because it is too tender to the point

of being mushy and textureless, as illustrated in Figure 1. When measured mechanically, tenderness is usually expressed in terms of some measure of resistance such as shear force in kilogram (kgF) or newtons (N), so that, in contrast to sensory scores, low values indicate more tender meat. Being aware of these distinctions is crucial when interpreting published data on meat tenderness. Unfortunately, there is no harmonization of the shear force values between the various measurement devices. The Warner–Bratzler values are

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approximately 0.7 times those of the MIRINZ tenderometer, but the relationships with other devices is not standardized. This is a limiting factor in international usage and comparisons of processing. Meat texture is a term that is sometimes used as a synonym for tenderness, which can be confusing as it is also used to denote the appearance of fineness or coarseness of meat. When used as a descriptor of palatability rather than appearance, the term will often have a broader meaning than tenderness and may include assessments of features such as mealiness, coarseness, cohesiveness, juiciness, chewiness, and fattiness as well as the force required to bite through a sample.

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Cooking temperature for 1 h (°C) Figure 2 Toughness (as assessed by Warner–Bratzler shear force) of uncooked meat and meat cooked to temperatures from 40 to 75 °C for samples of deep pectoral muscle from veal calves, yearling steers, and 5–7 year old cows. Veal meat was tougher at temperatures o50 °C because of higher collagen concentrations but was more tender at higher temperatures because the collagen present was more readily solubilized on heating. Adapted with permission from Bouton, P.E., Harris, P.V., 1972. The effects of cooking temperature and time on some mechanical properties of meat. Journal of Food Science 37, 140–144.

Muscle is a complex and sophisticated biological tissue. It is, therefore, not surprising that there are many structural and metabolic characteristics of meat that can affect its tenderness at the time of consumption or measurement following cooking. Some of these features, which are termed the intrinsic determinants of tenderness, are listed in Table 1. For two similar meat samples any difference in tenderness will sometimes be totally attributable to only one intrinsic determinant, but usually several of those listed in Table 1, and possibly others as well, are involved. This background on intrinsic determinants is relevant to the measurement of tenderness because the suitability of some methods will depend on the extent to which the various determinants are responsible for variation in tenderness.

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Cooking temperature for 1 h (°C) Figure 3 Results showing a large effect of cold shortening on changes in Warner–Bratzler shear force with increasing cooking temperature such that the toughening effect of cold shortening was only apparent after cooking to 60 °C or more. Samples were of beef semitendinosus muscle. Data adapted from Bouton, P.E., Harris, P.V., Shorthose, W.R., 1976. Dimensional changes in meat during cooking. Journal of Textural Studies 7, 179–192.

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Stage 1: The nature of the meat sample to be tested (e.g. method of cooking, size, orientation of fibres, temperature when tested).

Stage 2: The nature of the force or energy applied to the sample.

Stage 3: The nature of mechanical or physical actions applied to the sample.

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Stage 4: The nature of outputs from the device as measures of one or more aspects of meat tenderness.

Figure 4 Four stages during any mechanical method of meat tenderness measurement when the nature of the procedure followed may influence the measurements obtained.

Table 2 Examples of mechanical actions used to obtain measures of meat tenderness. Because of variation in tenderness within a muscle, it is usual practice to make from 6 to 12 measurements on cores (1 or 2 per core) from the same steak to obtain a satisfactory overall measurement Mechanical action

Examples of devices and the aspects of tenderness measured

1. A shearing action where the force required to cut through a meat sample is measured by the movement of metal blades relative to each other in a scissors-type action. Measurements made by the so-called shear devices often encompass tensile and compression stresses as well as shear stresses.

The most widely used device in this category is the Warner–Bratzler (WB) shear, which measures the force required to pull a cutting blade with rounded edges between two metal plates when a cylindrical core of meat is placed within a vee-shaped opening in the blade (Figure 5(a)). Alternative forms of this basic system involve the replacement of the veeshaped shearing edges with a straight horizontal edge, and the use of samples that are cuboidal rather than cylindrical. The use of cuboidal samples and a straight edge produces force-deformation curves with higher peak forces. A good example is the slice shear force device that uses a 50 mm square blade to shear through a slab of cooked meat that is 10 mm thick and 50 mm wide and that has been carefully prepared so that the shear is at right angles to the fiber direction. Although WB shear forces primarily reflect the myofibrillar contribution to tenderness, the difference between peak force and initial yield also provides an indication of the connective tissue contribution. The Volodkevich and MIRINZ tenderometers are good examples of instruments based on this principle, although a number of others have been produced. Results obtained are usually highly correlated with WB shear values and reflect primarily the myofibrillar contribution to tenderness, but differences in tenderness due to other determinants (e.g., connective tissue or marbling fat) also contribute. The ‘slice shear force’ system and the Meullenet–Owens razor shear are essentially biting-type actions, with a sharper ‘tooth’ in the latter case. A number of devices based on measures of compression have been developed with variation in the nature of the plunger and the way the meat sample is held. Compression tests are well suited to provide information on rheological parameters. Compression tests on uncooked meat have provided useful information on subsequent cooked-meat tenderness in some studies. These tests appear to reflect the connective tissue contribution to tenderness to a greater extent than shear or biting tests. This approach has been widely tested, usually with a bank of pins of some sort, but the results have been variable and this approach has not been widely used. The force required to separate muscle fibers perpendicular to their length is indicative of the connective tissue contribution to tenderness and is referred to as ‘adhesion.’ Other tensile strength measures are not commonly used. Moderately good correlations with sensory tenderness have been shown, but the approach is rarely used.

2. A biting action where the force required to bite through a sample is recorded. The biting part is usually in the form of one or two blunt metal that are vee-shaped ‘teeth’ of the same width as the sample that they bite through (Figure 5(b)).

3. A compressing action where a plunger is pushed into the meat sample which may or may not be constrained on two sides (Figure 4(c)). The maximum compression force is usually measured when the sample is compressed to a specified proportion (commonly 80%) of its initial thickness.

4. A penetrating action where the force required to penetrate the meat samples is measured. 5. Measures of tensile strength or the force required to stretch and break a meat sample by pulling in a direction either parallel to the fibers or perpendicular to the fibers. 6. Measures of the energy (usually electrical energy) required to mince a sample of meat under standard conditions. 7. Measures of the effects of a standard homogenizing treatment in terms of the size of the fragments produced. Commonly termed the myofibrillar fragmentation index (MFI).

This is primarily a measure of the fragility of the muscle fibers and is used as an index of the past proteolytic activity within the meat. The fragment size may be measured by levels of turbidity, by filtration, or by direct measures of fragment size using a microscope and often with the aid of an image analysis program.

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Tenderness Measurement

Measurement of Tenderness of Cooked versus Uncooked Meat Almost all meat is cooked before consumption, so tenderness measurements are best made on samples that have been cooked in the way the meat is normally eaten. This is the usual practice, but it would also be very useful if meat in an intact carcass could be assessed for tenderness (preferably in a nonintrusive manner) so that the information could be used as a grading criterion and premiums be given for carcasses yielding more tender meat. Unfortunately, the accurate measurement or prediction of cooked-meat tenderness using uncooked meat is difficult for two main reasons. First, changes in tenderness with cooking vary depending on the temperature and time involved and on characteristics such as collagen solubility and the ratio of collagen to muscle fibers in the meat. This is because the collagen contribution to tenderness decreases with increasing temperature as an increasing proportion is converted into insoluble gelatin, whereas the contribution of muscle fibers increases as the proteins within the fibers denature (see Figure 2). Results in Figure 2 illustrate this effect with the shear value for veal being highest at lower temperatures before collagen dissolves, but lowest at higher temperatures because collagen in veal is more soluble. Shear force can potentially be predicted by using noninvasive near-infrared spectroscopy (NIR) on uncooked meat where it has been shown to perform as well as by the reference method – it measures chemical changes as the meat tenderizes. However, NIR tenderness evaluations will be most accurately close to consumption and any prediction will, therefore, need to take account of both the time of measurement and cooking procedures. Second, some factors, such as cold shortening, have a major effect on the tenderness of cooked meat but no effect or even the opposite effect on uncooked meat. This is illustrated in Figure 3, where the toughening effect of cold shortening only became apparent when samples of beef semitendinosus were cooked to temperatures greater than 55 °C. Thus, it is only when tenderness differences are due to intrinsic determinants that have similar effects on cooked and uncooked meat that direct measures of tenderness on uncooked meat will be particularly useful. Because of variable cooking effects, it is important in tenderness research experiments that cooking methods be standardized with respect to sample size to be cooked, cooking temperature, final internal temperature, and cooking time. Cooking methods should also be similar to those commonly used for the type of meat involved. Cooking methods differ to some extent between meat research laboratories, which means that the direct comparison of results need to be made with care, but the fact that a range of methods are used increases the chance of important interactions between cooking parameters and other factors affecting tenderness being revealed.

Mechanical Methods of Tenderness Measurement Many devices have been developed to mechanically or physically measure the forces required to disrupt meat in some way. They can be categorized according to the way the force is

Downward-moving plates

Stationary ‘cutting blade’ Placement of meat sample (a)

Downward-moving ‘tooth’

Placement of meat sample

(b)

Stationary meat sample holder Downward-moving plunger

Placement of meat sample

(c)

Stationary meat sample holder

Figure 5 Diagrams showing three examples of types of mechanical action used to measure meat tenderness: (a) shearing; (b) biting; and (c) compressing. For some devices, the part shown as moving will be stationary and vice versa.

applied, the type of action (biting, shearing, compressing, etc.), the way the meat is prepared and orientated within the device, and the way the measurements are expressed (Figure 4). Most devices have a constant rate of movement (the crosshead speed) with changes in the force required being measured with movement through the sample to produce a force-deformation curve. For some devices, a sinusoidal change in rate of movement is employed. Alternatively, the force is increased at a constant rate, so that a curve of distance through the sample against force or time is produced. In both cases, the output most commonly reported is the maximum or peak force required to complete the test. Outputs in addition to the peak force that are sometimes reported include: 1. The area under the curve as a measure of the total work done. 2. An initial yield force represented by a shoulder or peak on the rising side of the force-deformation curve. This has been shown to be a useful indicator of the myofibrillar contribution to tenderness.

Tenderness Measurement

457

Table 3 Important aspects of the measurement of meat tenderness by sensory panels are illustrated here by comparing features of a consumer panel and a ‘descriptive,’ ‘analytical,’ or ‘trained’ panel Feature

Consumer panel

Descriptive or analytical panel

1. Broad aim

To assess the acceptability of the tenderness of the samples for a specified population of meat consumers.

To determine whether differences in tenderness or certain components of tenderness differ between groups of samples. Relatively low numbers may be used, especially if panelists are highly selected and trained.

2. Number of panelists

Relatively large numbers are required in order to obtain a representative sample of the population. A minimum of 6 would be needed for a trained panel, and absolute minimum of 50 for a consumer panel, with 100 more preferable. 3. Selection of panelists Selection should be such that a representative sample of the population of interest is obtained. 4. Training of panelists

Training is minimal or nonexistent as it is important that panelists represent typical consumers.

5. Site where samples are assessed

The site should be similar to the environment where meat is normally consumed such as in the home or at a commercial eating place. 6. Methods of sample Methods should match closely those normally used by preparation consumers, although detailed instructions on preparation methods will normally be given. 7. Number of samples A small number of samples and of questions per sample. and complexity of the Questions should be expressed in terms of tenderness questions asked acceptability or desirability rather than the level of tenderness or related characteristics. Acceptability scales are referred to as hedonic scales.

3. The difference between the peak force and initial yield force as an indication of the connective tissue contribution to tenderness. 4. The peak force or work required to pass a certain proportion of the way through or into a meat sample (used mainly with compression tests where compression by 20% or 80% is often used). 5. Rheological parameters such as stress and elasticity can be calculated when more than one cycle of actions are carried out for some forms of measurement such as by compression. 6. A measure of the electrical power required can be used when a meat sample is minced under standard conditions. Examples of types of mechanical action that have been used to obtain measures of meat tenderness are outlined in Table 2. This is not an exhaustive list and some devices involve more than one action, three examples of which are shown in Figure 5. For most mechanical measures of tenderness, the sample is arranged so that the force to cut or shear across muscle fibers is measured, but additional, and sometimes quite distinctly different, information is obtained when the sample is turned by 90° either horizontally or vertically from this usual orientation.

Sensory Methods of Tenderness Measurement The use of groups of people (sensory panels or taste panels) to assess the tenderness of meat samples is the ultimate test because tenderness has to be defined in terms of people’s

Panelists are commonly selected on their ability to detect small differences in the parameters of interest in a repeatable and consistent manner. Training with meat samples of the type to be assessed is important so that all panelists are conversant with the terms used and the ranges that are more likely to be encountered. Tasting is carried out under controlled conditions so that effects of extraneous variables (lighting, smells, other people, etc.) are minimized. Methods are closely controlled and designed to facilitate the acquisition of answers to the questions being addressed. The number of samples and the number and complexity of the questions can be greater because the panelists are trained. Panelists should not be expected to provide useful acceptability assessments. An example of characteristics covering a range of tenderness components is given in Table 4.

perceptions. Despite this, sensory methods are not used as widely as mechanical methods because of variation between people (even after a period of training), and because the approach is slower, more expensive and requires larger amounts of meat. Many types of sensory panel have been used, but their main features are summarized in Table 3 by comparing a consumer panel with a descriptive (also known as an analytical, trained, or laboratory) panel. The items listed in Table 4 illustrate the multidimensional nature of meat tenderness and hence the limitations of simple mechanical measures, although it should be noted that in that example the closely related characteristics of both tenderness and texture were being assessed. Within a sensory panel, there are several alternative ways in which panelists may record their assessments, including: 1. On a category scale of 5–9 steps, with each step given a specific description (e.g., a scale from extremely tender to extremely tough). A simplification is where only some of the steps are described. 2. A line scale, usually 100 or 150 mm in length, with no steps but with descriptors at the extremes and sometimes at the midpoint. Panelists mark a point on the line for each sample. 3. An open-ended line scale with a single anchor point that is described. This approach is referred to as ‘magnitude estimation’ and is a form of ratio scaling where the tenderness of one control sample is assigned a specific value and all others are compared with the control.

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Tenderness Measurement

Table 4 The complexity of tenderness as a characteristic of meat is illustrated by the examples in this table of characteristics of lamb texture that panelists were asked to assess in a study investigating the texture and tenderness of lamb meat Aspect of tenderness or texture 1. Elasticity on partial compression 2. First bite properties

3. Mastication properties

4. After-feeling properties

Subcategories within the aspect

a. b. c. d. e. a. b. c. d. e. f. g. h. i. j. k. l. m. n. a. b. c. d. e. f. g.

Compressibility Moisture release Fat amount Fattiness Cohesiveness Number of chews Chewiness Rate of breakdown Fibrousness Coarseness of fiber Moisture release Moisture absorption Cohesiveness Fattiness Fat amount Uniformity Density Connective tissue (6 options) Connective tissue amount Ease of swallowing Mouthcoating type (2 options) Mouthcoating amount Fat amount Particle type (15 options) Particle amount Tooth packing

5. Amplitude (an overall impression) Source: Adapted from Jeremiah, L.E., 1988. A comparison of flavour and texture profiles for lamb leg roasts from three different geographical sources. Canadian Institute of Food Science and Technology Journal 21, 471−476.

4. Two or more samples are ranked with respect to specific characteristics in a difference test. Panelists may also record the size of the difference between adjacent samples in a ranked list. The triangle test is a special form of difference test where panelists identify the different sample in a set of three, two of which are the same. Examples of ways in which sensory panels can be made more objective include: 1. Having the panelists count the number of chews required before meat is swallowed. 2. Using electromyography to record the action of the masseter (cheek) muscles during chewing. 3. Using time-intensity methodology whereby the panelist records (with the aid of a computer mouse) the change in tenderness as the meat is consumed.

Other Methods of Tenderness Measurement or Prediction Generally, methods other than those employing sensory panels or mechanical methods involve measuring

characteristics associated with only one or two intrinsic determinants of tenderness (Table 1) and hence will only be useful when only those determinants are responsible for the tenderness differences of interest. Thus, the value of these methods tends to be limited to particular situations. Examples are as follows: 1. Intramuscular fat content: Relationships with tenderness are not close but are almost always positive as explained in Table 1 (item 6). Although intramuscular fat levels are most often measured by solvent extraction, they can also be assessed reasonably accurately by NIR spectroscopy or by visual appraisal or VIA below. 2. Sarcomere length: Shorter sarcomere lengths, which can be measured by microscopy or laser diffraction, tend to be associated with less tender meat as explained in Table 1 (item 4). 3. Collagen content: Higher concentrations of collagen, as assessed by the hydroxyproline content in meat, will often mean lower levels of tenderness (Table 1, item 1). 4. Collagen solubility: High collagen solubility, as assessed by the extent to which it is dissolved by a standard heating treatment, tends to be associated with more tender meat (Table 1, item 2). 5. Ultimate muscle pH: Ultimate pH is either measured by a pH meter and probe or can be predicted from glycogen levels at slaughter. Its relationship with tenderness is outlined in Table 1 (item 3). 6. Video image analysis (VIA): Several characteristics can be measured by VIA including color, marbling fat, and connective tissue content, so the possibility of predicting tenderness exists. 7. Meat color: The relationship with tenderness is not close and probably arises at least in part from the link between color and pH. Meat color may be assessed subjectively with the aid of standard colors, with a reflectance spectrophotometer to give L⁎, a⁎, and b⁎ values or by VIA. 8. NIR spectroscopy: This technique will also provide a measure of a number of characteristics of meat when a cut surface of uncooked meat is scanned, including fat content and color as well as meat tenderness. The measurements can be made very quickly and preliminary results have been promising when it is used as a means of sorting carcasses or cuts of meat into two categories. For example, the terms ‘predicted tender’ and ‘not predicted tender’ have been used for the two categories in some studies. 9. SDS-PAGE and Western blotting: This technique can be used to quantitate the proteolysis of muscle proteins, which is usually associated with more tender meat. The proteins which are usually targeted are troponin-T, which breaks down to a 30 kDa protein, titin, which breaks down from a singlet to a doublet or triplet, and nebulin. Other muscle proteins have also been used as indicators of proteolysis. 10. Myofibrillar fragmentation index (MFI): This technique can also be used to quantitate the proteolysis of muscle proteins, which is usually associated with more tender meat. The procedure involves homogenizing the meat in a

Tenderness Measurement

standard way in buffers and measuring the size of the fragmented myofibrils to get an index.

See also: Carcass Composition, Muscle Structure, and Contraction. Chemical and Physical Characteristics of Meat: Chemical Composition; Palatability. Conversion of Muscle to Meat: Aging; Rigor Mortis, Cold, and Rigor Shortening. Cooking of Meat: Cooking of Meat. Measurement of Meat Quality: Measurements of Water-holding Capacity and Color: Objective and Subjective. On-Line Measurement of Meat Quality. Prediction of Meat Attributes from Intact Muscle Using Near-Infrared Spectroscopy. Sensory and Meat Quality, Optimization of. Tenderizing Mechanisms: Chemical; Enzymatic; Mechanical

Further Reading AMSA, 1995. Research Guidelines for Cookery, Sensory Evaluation and Instrumental Tenderness Measurements of Fresh Meat. Chicago: American Meat Science Association. Bouton, P.E., Harris, P.V., 1972. The effects of cooking temperature and time on some mechanical properties of meat. Journal of Food Science 37, 140–144.

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Bouton, P.E., Harris, P.V., Shorthose, W.R., 1976. Dimensional changes in meat during cooking. Journal of Textural Studies 7, 179–192. Chrystall, B., 1994. Meat texture measurement. In: Pearson, A.M., Dutson, T.R. (Eds.), Quality Attributes and Their Measurement in Meat, Poultry and Fish Products. Advances in Meat Research, vol. 9. London: Blackie Academic, pp. 316–336. Harris, P.V., 1976. Structural and other aspects of meat tenderness. Journal of Texture Studies 7, 49–63. Jeremiah, L.E., 1988. A comparison of flavour and texture profiles for lamb leg roasts from three different geographical sources. Canadian Institute of Food Science and Technology Journal 21, 471–476. Lawless, H.T., Heymann, H., 1998. Sensory Evaluation of Food. Principles and Practice. New York: Chapman & Hall. Lepetit, J., Culioli, J., 1994. Mechanical properties of meat. Meat Science 36, 203–237. Prieto, N., Roehe, R., Lavin, P., Battern, G., Andres, S., 2009. Application of near infrared spectroscopy to predict meat and meat products quality: A review. Meat Science 83, 175–186. Stephens, J.W., Unruh, J.A., Dikeman, M.E., et al., 2004. Mechanical probes can predict tenderness of cooked beef longissimus using uncooked measurements. Journal of Animal Science 82, 2077–2086. Tornberg, E., 1996. Biophysical aspects of meat tenderness. Meat Science 43, S175–S191. Wheeler, T.L., Vote, D., Leheska, J.M., et al., 2002. The efficacy of three objective systems for identifying beef cuts that can be guaranteed tender. Journal of Animal Science 80, 3315–3327.

THERMOPHYSICAL PROPERTIES

SJ Lovatt, AgResearch Ltd., Hamilton, New Zealand r 2014 Elsevier Ltd. All rights reserved.

Glossary

Latent heat The amount of heat that is released or absorbed when a material changes phase between solid and liquid (melting/freezing), liquid and gas (boiling/ condensing), or solid and gas (subliming/deposition). Moisture diffusion The movement of water through a solid.

Density The ratio of an object’s mass to its volume. Enthalpy The total heat content of an object, often expressed per unit mass. Freezing temperature The temperature at which a material starts to freeze. Heat capacity The derivative of enthalpy with temperature, under either constant pressure or constant volume conditions.

Introduction

ρ¼

The thermophysical properties of meat products are relevant for many purposes, including:

• • • • •

calculating chilling, freezing and cooking times, and heat loads; designing drying, salting, and other value-adding processes; modeling meat processing operations; calculating yields and mass balances in meat processing; and calculating behavior during transportation.

The quality and microbial status of a meat product are usually strongly dependent on the thermal and physical processes to which the meat is subjected, so the ability to model thermal and physical processes accurately is important when one needs to calculate the meat quality attributes and the microbial growth that may result from these processes. In turn, accurate knowledge of the thermophysical properties of meat products and the materials typically found in meat processing operations is essential to the accurate modeling of the thermal and physical processes. Typical values and simple methods of estimating these properties are provided in this article but when accurate values are required for process design (for instance), reference should be made to the books and articles that report data for the specific materials to be used. The SI unit for temperature is Kelvin, K, but the degree Celsius, 1C, is the same size and is often more convenient for the temperatures of importance to meat science, so both temperature units are used in this article.

Density The density of a substance is the ratio of its mass to its volume, as shown in eqn [1].

460

m V

½1

In this equation, ρ is the density in kg m3, m is the mass of the substance in kg, and V is the volume of the substance in m3. The specific volume of the substance, v, in m3 kg1, is defined as the reciprocal of the density, as shown in eqn [2]. v¼

1 ρ

½2

The concept of density is not as straightforward as one might imagine at first, because it depends on both the mass and volume of the substance. Mass is fairly simple and it can be measured with considerable accuracy but the meaning of a substance's volume is more complex. The most important issue in measuring volume is whether one should or should not include any void space that may be around or within the substance in which one is interested. A cut of fresh meat would not be expected to contain much void space within itself. Its volume could, therefore, be measured by (for instance) measuring the amount of liquid that it displaces when it is completely submerged. Even then, meat will typically absorb some moisture over time and so the amount of liquid displaced will reduce as this absorption takes place. This effect is particularly important for pieces of meat with high ratios of surface area to volume, such as poultry or offal. A package containing meat could contain a substantial amount of void space, often air, and one must then take considerable care. The appropriate volume to use when calculating density will depend on the purpose for which it is required. For example, if one was interested in the mass of packaged meat that one could fit into a shipping container, one would use the volume of the whole package and therefore calculate the figure known as the ‘bulk density.’ Alternatively, when one is calculating the chilling time for the package, one often needs to convert the thermal properties from a

Encyclopedia of Meat Sciences, Volume 3

doi:10.1016/B978-0-12-384731-7.00133-1

Thermophysical Properties

volumetric to a mass basis. In this case, one should use the volume of the meat contained in the package. Finally, some meat products such as free flow frozen meat pieces can contain significant amount of air within their overall dimensions, so the relevant density will depend on whether the product is being heated or cooled as individual pieces or as a collection of pieces in a package. Fresh meat comprises mostly water, protein, fat, and, sometimes, bone. Dry protein has a density somewhat greater than that of water and dry fat has a density somewhat less than that of water. Many products that are predominantly made of lean meat, therefore, have a density close to that of water, i.e., between approximately 950 and 1080 kg m3 in the range 0– 100 1C. If it is necessary to estimate the density of a meat product with greater accuracy, the volume of the whole product is usually equal to the sum of the volumes of the components that make up that product. Exceptions to this rule apply when the components dissolve in each other (as with alcohol and water, for instance), but this does not usually apply for the components making up meat products. Thus, if one knows the composition of a meat product, one can estimate its density as shown in eqn [3]. n x 1 i ¼ ∑ ρ i ¼ 1 ρi

½3

In eqn [3], xi is the mass fraction of the ith component, ρi is the density of the ith component in kg m3, and n is the number of component materials in the meat product. Table 1 shows density values for some common components of meat products at typical processing temperatures. The densities of most materials vary with temperature, generally decreasing as the material's temperature increases. For water-based materials, such as meat, the density of the water component is affected by its hydrogen-bonding behavior, with the result that the density of liquid water reaches a peak at approximately 4 1C. Similarly, although the densities of most materials increase when they freeze, water is again unusual and ice is less dense than liquid water under most conditions. The density of a meat product below its freezing temperature can be estimated using eqn [3], but it is necessary to include both water and ice as components and also to estimate the fraction of water that is still liquid and the fraction that has become ice from the temperature, T, of the meat. An approximate value of the ice fraction at a given temperature, below the initial freezing temperature, is given by eqn [4], where Tf is the initial freezing temperature of the meat in 1C, xice is the mass fraction of ice, and xwater is the total mass fraction of water (frozen and unfrozen). Table 1 Approximate density values for some meat components at typical food processing temperatures Component

Density (kg m3)

Water Ice Protein Fat Air

1000 920 1400 900–950 1.29 (at 0 1C)

Tf xice ¼1 xwater T

461

½4

Equation [4] overestimates the ice fraction when the temperature T is low (typically  20 1C and below) because it does not consider the bound water in the food, which never freezes no matter how low the temperature becomes.

Freezing Temperature The water content of meat is in the form of a complex solution with many solutes present in different concentrations. The presence of these solutes depresses the initial freezing temperature of the solution (and, hence, of the meat) below the freezing temperature of pure water (0 1C). The freezing temperature of any solution is depressed from the freezing temperature of the pure solvent. If one assumes that the solute is insoluble in the solid solvent, the freezing point of the solution is determined by the equilibrium of chemical potentials between the pure solid and the liquid solution. The details of the mechanism are described in physical chemistry texts. In simple terms, when the first ice crystal forms in the meat, it comprises almost pure ice, thereby causing the diffusion of the solutes into the remaining solution, increasing the concentration of that solution, and further depressing the solution’s freezing temperature. As additional ice crystals form, the concentration of the remaining liquid increases further and its freezing temperature is depressed still further. This results in meat freezing progressively over a range of temperatures. Meat has a freezing temperature range, depending on the concentration of the water solution at any point in time, so the expression ‘freezing temperature’ usually refers to the initial freezing temperature at which ice crystals first begin to form. Even this temperature can be difficult to determine, because the formation and growth of ice crystals requires that there be sufficient ‘undercooling’ or ‘supercooling’ below the initial freezing temperature to initiate nucleation and drive crystal growth. At high freezing rates (as may be found in cryogenic freezing) or in some special circumstances, the amount of undercooling can be many degrees Celsius. At typical meat industry freezing rates, however, undercooling amounts are typically no more than a few tenths of a degree Celsius, and can, therefore, be neglected. The need for undercooling means, among other things, that it is possible to store meat in an environment that is a little colder than its freezing temperature without ice crystals beginning to form, in order to maximize its storage life while maintaining a chilled state. The initial freezing temperature of meat depends on its composition, but  1 1C is often assumed to be representative for lean meat with a high (approximately 70–80%) moisture content. Meat products with higher fat content, added components, such as salt, and dried meats can have freezing temperatures several degrees lower than this. Compositional approaches based on the average molecular weight of solutes have been found to estimate the initial freezing temperature of meat with an average absolute error of approximately 0.25 1C. If a more precise estimate of the initial

462

Thermophysical Properties

freezing temperature is required, the data must be obtained by measurement.

Glass Transition A glass is a metastable noncrystalline solid with a very high viscosity. This state can be formed when a liquid is cooled very quickly and its molecules slow their movement to the point where they cannot reach the preferred crystallized state. The characteristic temperature, below which a glass is formed, is known as the ‘glass transition temperature,’ or Tg′. Because the rate of deterioration of a food product is often determined by the diffusion of solutes through the product, the ability to store products near or below Tg′, where this diffusion rate is very slow, could be expected to greatly extend the storage life of a product. The absence of ice crystals in a glassy product is also advantageous because the growth of ice crystals can damage cell walls and cause solute diffusion that can degrade the quality of the product over time, or when it is thawed. Tg′ is typically measured using a differential scanning calorimeter, but it is difficult to measure accurately. Values have been reported by some researchers to be in the range  11 1C to  13 1C for mackerel, cod, trout, mutton, and beef, and  13 1C to  17 1C for chicken.

Enthalpy, Latent Heat, and Specific Heat Capacity Enthalpy (for which the symbol is usually H) is the heat content of a substance per unit mass of that substance, measured in J kg1. Thus, to change the temperature of a kilogram of meat from an initial temperature, T1, to a higher temperature, T2, it would be necessary to add an amount of heat equal to the difference between the enthalpy of that meat at T1 and its enthalpy at T2. Enthalpy has no physically defined zero point, so zero points can be defined arbitrarily. This has the unfortunate consequence that different authorities have defined the zero point differently, and so it is important to ensure that the zero point is defined consistently (or that an appropriate adjustment is made) when comparing enthalpy data from different sources. For foods, the zero point is often defined to be  40 1C (so that enthalpies in normal ranges of temperature are always positive), or sometimes 0 1C, both at a pressure of 1 atm. For other materials that are commonly used in food processing (refrigerants or steam, for instance), the zero point can be defined quite differently – for instance, enthalpy may be set equal to zero for saturated liquid at the material's triple point. None of this should be important as calculations should only be done with enthalpy differences, but it can be a source of confusion. Similarly, there is no significance in an enthalpy value being less than zero because this is just a result of where the zero point has been defined. The specific heat capacity, C, is the amount of heat required to raise the temperature of a unit mass of material by a unit temperature change, measured in J kg1 K1. Specific heat is usually defined under conditions either at constant volume (written as Cv) or constant pressure (written as Cp). This can

make a significant difference for the specific heat of a gas but, because the pressure dependence of specific heat for food materials is small except at extremely high pressures, specific heat values for foods are usually reported at constant pressure and these values can be applied with good accuracy for all conventional food processing operations. Enthalpy and specific heat are related by eqn [5]. C¼

dH dT

½5

When freezing, a substance will release a considerable amount of heat without any temperature change as its liquid content becomes solid. This is known as the latent heat of freezing, Hf, measured in J kg1. For a pure substance, such as water, this results in a discontinuity in eqn [5] at the freezing temperature, Tf, because the enthalpy changes substantially with no change in temperature. Even for meat and other food products, C can become quite large near the initial freezing temperature and this can make some calculations relatively difficult. As a result, it is often better, near the freezing point, to calculate in terms of enthalpy instead of specific heat, if possible. Hf for water is 334 kJ kg1, but the water content of meat becomes ice over a range of temperatures, as estimated by eqn [4]. As a consequence, some of the water content of a meat product will remain unfrozen even well below the initial freezing temperature and the latent heat content of meat is released during freezing, based on the change in ice fraction with temperature. For the temperature ranges of practical interest in meat processing, the heat capacity of meat can be estimated from the heat capacities of its components, weighted by their mass fractions, as shown in eqn [6], where Ci is the heat capacity of the ith component in J kg1 K1. n

½6

C ¼ ∑ Ci xi i¼1

When no phase change, such as freezing, takes place, the heat capacities of most materials change only relatively slowly with temperature and so can be assumed to be constant. Some approximate heat capacities for meat components are shown in Table 2. The heat capacity of meat fat can be strongly dependent on the composition of that fat so, for accurate work, it is necessary to understand that composition in detail or to measure the heat capacity. This can be particularly important for cooking processes, where each fat fraction will melt at a different temperature. The latent heat required to melt each fat fraction can be accounted for either by assuming a higher effective heat capacity Table 2 Approximate heat capacity values for some meat components at typical food processing temperatures Component

Heat capacity (kJ kg1 K1)

Water Ice Protein Fat Air

4.18 2.09 2.01 1.98 1.005

Thermophysical Properties

for the overall fat in that temperature range, or by dealing separately with the thermal properties of each fat fraction. If eqn [6] is used to calculate a specific heat capacity for frozen meat of a specific composition, CS, and for unfrozen meat of the same composition, CL, the change in enthalpy, DH, between a frozen temperature, T1, and an unfrozen temperature, T2, can be estimated from eqn [7], where xice is the mass fraction of ice at the temperature T1. DH ¼ CS ðTf  T1 Þ þ Hf ,water xice þ CL ðT2  Tf Þ

½7

It is sometimes useful, particularly when modeling food processing operations, to express enthalpy, latent heat, and specific heat capacity in volumetric terms (i.e., J m3, J m3 and J m3 K1, respectively). This can be achieved by multiplying the mass-based property values by the density of the substance.

Thermal Conductivity The thermal conductivity, k, of a material defines the ease with which heat passes through the material, measured in W m1 K1. For a slab of material (e.g., meat) where heat passes directly from one side to the other (i.e., the edges are perfectly insulated), thermal conductivity is defined by eqn [8]. Q¼

kA ðTa  Tb Þ x

½8

In eqn [8], Q is the rate of heat flow through the slab in W, A is the cross-sectional area of the slab perpendicular to the direction of heat flow in m2, x is the thickness of the slab in the direction of heat flow in m, and Ta and Tb are the temperatures on each surface of the slab in 1C. Although thermal conductivity is defined in eqn [8] as applying to a slab, the concept applies equally to any physical geometry. The thermal conductivity of a substance depends on the composition of the substance, as with heat capacity, but it is also strongly dependent on the structure of the substance. As a consequence, it is considerably more difficult to predict the thermal conductivity of a material than to predict heat capacity, for instance. Literature reviews have listed dozens of generic theory-based prediction methods. Including empirical curve-fits just for food products would increase this number considerably. At the same time, thermal conductivity is relatively difficult to measure with high levels of accuracy and so even the measured data reported in the literature are often subject to uncertainties of perhaps 75–10%. The accuracies of thermal conductivity prediction models are strongly dependent on the ratios of the component thermal conductivities. For small component conductivity ratios, different models typically produce similar, accurate predictions. Thus, referring to Table 3, for fresh meat comprised only of water, protein, and fat, the largest ratio of thermal conductivities is approximately 3 and many models are good enough for most purposes, including an average of the component thermal conductivities weighted by the component mass fractions, as was used above for specific heat capacity. For frozen meat containing ice, unfrozen water, protein, and fat, the thermal conductivity ratio is

463

Table 3 Approximate thermal conductivity values for some meat components at typical food processing temperatures Component

Thermal conductivity (W m1 K1)

Water Ice Protein Fat Air

0.57 2.2 0.18 0.18 0.025

approximately 12 and it is important to take care over which model is used. For meat packages that include frozen meat and air, the thermal conductivity ratio is nearly 100 and substantial errors could be made by using the wrong predictive model. Owing to the substantial difference between the thermal conductivity of water and that of ice, the thermal conductivity of meat also changes substantially as it freezes or thaws. Accurate data have been reported in the literature for a range of meat products. A review of the literature shows that for fibrous materials, such as meat, it can even be necessary to determine whether the heat flow is across or along the length of the meat fibers, because the thermal conductivity can be significantly different for these two cases. For rough calculations, however, it is sometimes sufficient to assume typical thermal conductivity values of approximately 0.5 W m1 K1 for unfrozen and 1.5 W m1 K1 for frozen lean meat.

Moisture Diffusivity The diffusivity of moisture through a material can be defined by analogy with thermal conductivity, following eqn [8], but replacing heat flow with moisture flow and temperature with moisture content. Just as knowledge of the thermal conductivity of a meat product is important when designing or analyzing thermal processes, knowledge of the moisture diffusivity is important when designing or analyzing processes that involve drying. Drying can occur deliberately, such as when manufacturing jerky or biltong, or as a side effect of another process, such as when chilling unwrapped meat cuts or carcasses in air. Moisture diffusion is arguably even more sensitive to the attributes of the material through which the moisture is to pass than is heat diffusion. As a result, there have been relatively few reliable measurements of moisture diffusivity in meat products and even these measurements differ considerably in their reported values, apparently due to subtle differences in attributes between the different meat products studied. In addition, for meat and many other materials, moisture diffusivity is strongly dependent on the moisture content of the material. Many methods for measuring moisture diffusivity rely on drying some or all of the sample, so the diffusivity value measured by those methods can change substantially during the measurement process. The most reliable moisture diffusivity values reported for meat to date have probably been those for raw minced beef, where measurements have ranged from 0.3  1010 to

464

Thermophysical Properties

5  1010 m2 s1, with dependencies reported based on moisture content and temperature. The accurate measurement and estimation of moisture diffusivity for whole muscle meat remains an active area of research.

See also: Canning. Cooking of Meat: Heat Processing Methods. Modeling in Meat Science: Refrigeration. Refrigeration and Freezing Technology: Applications

Further Reading Amos, N.D., Willix, J., Chadderton, T., North, M.F., 2008. A compilation of correlation parameters for predicting the enthalpy and thermal conductivity of solid foods within the temperature range of  40 1C to þ 40 1C. International Journal of Refrigeration 31, 1293–1298. ASHRAE, 2010. ASHRAE Handbook − Refrigeration, SI ed. Atlanta, GA: American Society of Heating, Refrigerating and Air-Conditioning Engineers. Atkins, P., De Paula, J., 2009. Atkins' Physical Chemistry, ninth ed. Oxford: Oxford University Press. Boonsupthip, W., Sajjaanantakul, T., Heldman, D.R., 2009. Use of average molecular weights for product categories to predict freezing characteristics of foods. Journal of Food Science 74 (8), E417–E425. Brake, N.C., Fennema, O.R., 1999. Glass transition values of muscle tissue. Journal of Food Science 64 (1), 10–15.

Carson, J.K., 2006. Review of effective thermal conductivity models for foods. International Journal of Refrigeration 29, 958–967. Green, D.W., Perry, R.H. (Eds.), 2007. Perry's Chemical Engineers' Handbook, eighth ed. New York, NY: McGraw-Hill. McCabe, W.L., Smith, J.C., Harriott, P., 2004. Unit Operations of Chemical Engineering, seventh ed. New York, NY: McGraw-Hill. Motarjemi, Y., Hallstrom, B., 1987. A study of moisture transport in minced beef. In: Jowitt, R., Escher, F., Kent, M., McKenna, B., Roques, M. (Eds.), Physical Properties of Foods, vol. 2. London: Elsevier, pp. 61–64. Rahman, M.S., 2009. Food Properties Handbook, second ed. Boca Raton, FL: CRC Press. Sahagian, M.E., Goff, H.D., 1995. Chapter 1: Fundamental aspects of the freezing process. In: Jeremiah, L.E. (Ed.), Freezing Effects on Food Quality. New York, NY: Marcel Dekker, pp. 1–50. Sunooj, K.V., Radhakrishna, K., George, J., Bawa, J.S., 2009. Factors influencing the calorimetric determination of glass transition temperature in foods: A case study using chicken and mutton. Journal of Food Engineering 91, 347–352.

Relevant Websites https://www.ashrae.org/ American Society of Heating, Refrigerating and Air-Conditioning Engineers. http://www.iifiir.org/ International Institute of Refrigeration.

Index Notes Cross-reference terms in italics are general cross-references, or refer to subentry terms within the main entry (the main entry is not repeated to save space). Readers are also advised to refer to the end of each article for additional cross-references – not all of these cross-references have been included in the index cross-references. The index is arranged in set-out style with a maximum of three levels of subheading. Major discussion of a subject is indicated by bold page numbers. Page numbers suffixed by T, F, and B refer to Tables, Figures, and Boxes respectively. vs. indicates a comparison. This index is in letter-by-letter order, whereby hyphens and spaces within index headings are ignored in the alphabetization. For example, acid meat is alphabetized after acidification, not after acid(s) or F-value is after Fusarium, and not at the start of the F section. Prefixes and terms in parentheses are excluded from the initial alphabetization. Where index subentries and sub-subentries pertaining to a subject have the same page number, they have been listed to indicate the comprehensiveness of the text.

A Aab gosht 1:539 Abalone 3:385 Abattoirs animal inspection on arrival 3:99, 3:99F definition 3:290 lairage see Lairage/lairaging mechanical stunning audits 3:416 parasitic meatborne infection detection 3:40–41 quality management activities see Quality management activities/systems Salmonella monitoring/incidence see under Salmonella transport of animals to see Transport see also Slaughter; Slaughter-line operation Abomasal ulcers, somatotropin-treated steers 2:184 Abomasum 2:471, 2:471F Abscess(es) somatotropin-treated steers 2:184 steroid hormone implant sites 2:66 Absolute humidity 3:50, 3:50F definition 3:50, 3:50 Absorption refrigeration 3:200 Abusive acts, detrimental to welfare during handling/transport 3:87 Accelerated solvent extraction (ASE), fat analysis 1:182, 1:207 Acceptable daily intake (ADI) 3:218 definition 3:214 Acceptance sampling see Sampling, acceptance Accreditation definition 2:145 laboratory see Laboratory accreditation Accreditation body, definition 2:145 Accumulator tanks, brine injectors see Brine injectors Accuracy definition 1:316, 2:481 pig carcass classification online instruments 1:319 reference methods 1:317, 1:317F

precision and 2:481, 2:481F Acetate agar, lactic acid bacteria enumeration 2:309 Acetic acid beef carcasses, use on 3:289 carcass decontamination 2:278 meat tenderization 3:433 Acid(s) added 1:300 dissociation constant 1:262 organic see Organic acid(s) Acid–adaptation responses 2:288 definition 2:285 Acid ferrimyoglobin peroxide 1:247T, 1:248 Acidification 1:10–11 Clostridium botulinum control in meats 2:333 environmental, meat production-related 1:504 Acidified sodium chlorite (ASC) solutions, carcass decontamination 2:278 Acidifiers, in meat products 1:10–11 Acid meat pale, soft, and exudative meat vs. 1:341 pork 1:339F, 1:340 PRKAG3 gene mutations 1:341, 1:342T weight loss 1:341 poultry 1:343 Acid phosphates, functions 1:299 Acquired resistance 2:413–414 definition 2:412 see also Antibiotic resistance Acrylamide, formation during extrusion cooking 1:568–569 Acrylonitriles, packaging film chemistry 3:22 Actin 1:157, 1:158F, 1:238, 1:358 definition 1:358, 1:370 denaturation 1:371 water binding 1:257 see also Actomyosin; Muscle contraction; Myofibrillar proteins Actinidin 3:441 Actinobacillus pleuropneumoniae, specific pathogen free pig programs 2:188

Activated carbon, boar taint control 1:100–101, 1:100F Active packaging 2:283, 3:24–25 definition 3:19 Actomyosin cycle 1:157, 1:163F see also Muscle contraction definition 1:358 gels 1:270 see also Myofibrillar proteins Added water 1:299 calculation 1:170–171 nitrogen factor and 1:170–171, 1:170T, 1:299 regulations 1:299 Additives (meat/meat products) 1:299–300, 3:80 advantages/disadvantages 1:299–300 color 3:81 see also Colorings/coloring agents extenders see Extenders fermented sausages 2:2 fresh sausage 3:262, 3:263T functional see Functional ingredients, meat products permitted quantities 1:300 raceway curing, hides 1:116, 1:120T regulations 1:7, 1:200, 1:201T, 1:443 residual 3:223 see also specific additives Additives, feed see Feed additives Adenosine triphosphatase (ATPase), definition 2:442 Adenosine triphosphate (ATP) consumption, muscle 1:346 definition 2:471 depletion, rigor mortis and 1:360, 1:361F, 1:362F, 1:363, 1:363 formation 1:346, 1:353 muscle concentration 1:363 muscle contraction role 1:155, 1:157, 1:162F, 1:163F, 1:358–359, 1:360, 1:361F Adenosine triphosphate (ATP) buffer creatine phosphate 1:355

465

466

Index

Adenosine triphosphate (ATP) buffer (continued) definition 1:353 Adenosine triphosphate (ATP)-related compounds, postrigor fish 2:9, 2:10F measurement, freshness assessment 2:9–11 Adenylyl cyclase, lipolysis 2:47 ADG see Average daily gain (ADG) Adhesion, planktonic cells, biofilm formation 1:64–67, 1:65T Adhesion/binding, definition 1:267 Adipocyte(s) 1:160 age evaluation 2:45 aroma compound storage 1:259 brown adipose tissue 2:43 definition 2:43 development 1:224, 1:224F, 1:225F differentiation 2:45, 2:46F fatty acid uptake from plasma 2:47 glucocorticoid receptors 2:51 lipid droplets 2:45, 2:46F metabolic pathways 2:46F postmortem catabolism 1:354 somatotropin effects 2:80 Adipogenesis, endocrinology 2:51 Adipokines 2:44 Adiponectin, growth 2:54 Adipose depots 2:79 Adipose tissue 1:222–234 beta-adrenergic agonist effects 2:67 brown see Brown adipose tissue (BAT) cellularity 1:163, 1:165T see also Adipocyte(s) development 2:43–48 form 2:79 function 2:43, 2:79 gender effects 2:79–80 genetic effects 2:79 growth 2:75 age effects 2:76, 2:79 hormonal effects 2:80 hyperplasia 2:79 interventional strategies 2:80 nutritional effects 2:80 physiology 2:79 human, distribution 2:109 intermuscular see Intermuscular fat intramuscular see Intramuscular fat lipid accumulation 1:224, 1:224F, 1:225F lipid composition 1:222 see also Lipid(s), fatty acid composition myostatin expression 1:466 restricted feed intake 2:80 somatotropin effects 2:76–77, 2:77T stearoyl-coenzyme A desaturase activity see Stearoyl-coenzyme A desaturase (SCD) steroid hormone effects 2:65–66 subcutaneous see Subcutaneous fat types 2:43 white see White adipose tissue (WAT) see also Fat; Lipid(s) Adipose triglyceride lipase (ATGL) 2:47 Adrenaline 2:177 growth 2:53–54, 2:75–76 lipolysis 2:47

Adulteration definition 2:265 meat 2:265 Advanced glycation end products, flavor development and 1:379 Advanced meat recovery 2:271 definition 2:270 see also Mechanically recovered meat (MRM) Aepyceros melampus (impala) meat 3:349, 3:352T Aerobic, definition 2:152, 2:289 Aerobic metabolism, muscle fibers 1:155–156, 1:162F Aerobic plate count (APC) 2:302–303, 2:303 Aerobic spoilage, factors affecting see Spoilage, factors affecting Aerobic treatment, manure 2:155 Aeromonas 2:317–323 antibiotic sensitivity and resistance 2:320–321 controlling numbers in foods 2:320 habitats 2:318 human and veterinary clinical infections 2:318–320, 2:319T as indicator organism 2:303 isolation 2:321 molecular characterization of isolates 2:321 occurrence in raw meat and poultry 2:318 PCR detection 2:321, 2:322T phenotypic characteristics 2:318, 2:319T restriction length polymorphism studies 2:321–322 virulence factors 2:318 virulence genes, distribution 2:321 Aeromonas agar (AA) 2:321 Aeromonas caviae 2:317–318, 2:319T Aeromonas hydrophila 2:317–318, 2:319T Aeromonas veronii 2:317–318, 2:319T Aflatoxins 2:401, 2:402 Africa livestock numbers 2:212T cattle 2:212T, 2:213, 2:213T pigs 2:212T, 2:216 sheep and goats 2:212T, 2:214 production systems 2:190–191 birds guinea fowl 2:192 ostriches 2:191 camels 2:193 cane rats 2:196 crocodiles 2:196 game animals 2:194, 3:346 goats 2:190–191, 2:194, 2:195 pastoralism cattle production 2:214 sheep and goat production 2:215 see also South Africa African ungulates 3:348–349 carcass yields 3:349, 3:351T commercially harvested species 3:349 game meats 3:349, 3:351T, 3:352T zoonotic disease 3:349 see also individual species

Aftertastes 1:252, 1:258 Age connective tissue affected by 1:324 muscle fiber type affected by 2:445 Aggregative adherence, enteroaggregative E. coli 2:357–358 Aging, meat 1:329–338, 1:362, 3:270, 3:438 acceleration by injection of calcium and other agents 1:336 beef 1:335 commencement 1:331 connective tissue changes 1:324 definition 1:142, 1:329–330, 1:486, 3:267, 3:431, 3:443 dry 1:337, 2:228, 3:270 duration 2:228 effect on water-holding capacity 1:278 electrical stimulation and 1:335, 1:336F factors influencing 1:329–330, 1:330F biochemical factors 1:333–334, 1:334F physical factors 1:333, 1:333F preslaughter stress 1:334, 1:335F temperature 1:331–332, 1:332F, 1:334, 1:334F factors that reduce 1:335–336 freezing/thawing and 1:336 hot boning and 1:335 market specifications 2:233–234 measurement 1:336–337 meat tenderness and 1:257 mechanism 1:331 packaging and 1:337 pork 1:335 reduced 3:269 sensory aspects of meat quality and 3:270 species and breed differences 1:335 variability 1:332–333 wet 1:337, 2:228, 3:270 see also Tenderization Agitation, rendering 1:128 Agouti 2:196 Agricultural intensification, impact on biodiversity 1:503 Agricultural Marketing Service (AMS), USDA, Beef Quality Grading System, meat palatability 1:253–254, 1:254F Air-based refrigeration systems primary air blast freezing systems 3:185–186 poultry carcasses 3:185, 3:185F secondary chilling/freezing systems 3:187, 3:187F Air blast cooling systems 3:206–207 Air chilling, evaporative 2:226 Air chill rooms 2:226 Air conditioning, meat products, effects on 3:178 Airflow patterns, ovens 3:136F, 3:138–139, 3:138F Air quality, manure and 2:155–156 Air temperature chilling of meat 2:226 effect on solid food drying 1:474 measurement error sources 3:62–63 ovens 3:136

Index

Air thawing 2:227, 3:205–206, 3:205F advantages/disadvantages 3:205 stages 3:205–206, 3:205F Air transport chilled foods, recommendations 2:237 meat/meat products 2:228, 2:237 Air velocity for chilling of meat 2:226 effect on solid food drying 1:474 measurement see Anemometers ovens 3:136F, 3:138–139, 3:138F Alaria alata 3:35–38T Aldehydes rancidity/warmed-over flavor and 3:395 smoke condensates 3:319 Strecker 1:394, 1:395F warmed-over flavor 1:411 Al-dhabh definition 3:209 see also Halal slaughter Algebraic models, meat quality 2:427–428, 2:427F Alkaline cleaners heavy-duty 1:513 mild 1:513 strong 1:513 Alkaline phosphates emulsion-type sausages 3:256 oxidation inhibition 1:414 Alkylpyrazines, formation via Maillard reaction 1:396, 1:396F Alkylthiazoles, formation via lipid–Maillard interactions 1:399, 1:399F Allergic responses, to meat extenders 1:2 Allometric growth 2:76 definition 2:56, 2:75, 3:363 see also Growth; Growth patterns Allometric growth ratio 2:57, 2:70 Allometry 2:56–57, 2:70–71 Alpaca (Vicugna pacos) 2:193 meat 3:354 Alpha (a)-hemolysis, definition 2:340 Alternaria 2:395, 2:398F Alum (aluminum potassium sulfate) tanning process 1:121 Amadori nonvolatile compounds, cooked meat flavor 1:259 American Meat Science Association (AMSA) 3:148T American Society for the Prevention of Cruelty to Animals (ASPCA) pen 3:212, 3:212F, 3:213 American Society of Animal Science (ASAS) 3:148T American-style leg (shank-off leg), lamb 1:463 Americas livestock numbers 2:212T cattle 2:212T, 2:213 pigs 2:212T, 2:216 sheep and goats 2:212T, 2:214 see also Brazil and South America; North American meat products; United States (US) Amino acid(s) 1:210 analysis 1:209–210

chromatographic separation 1:210–211 hydrolysis 1:210 dietary human nutrition 2:119 in pig feeds 2:458–459, 2:459T microbial degradation, flavor development role in dry sausages 3:252 requirements, poultry 2:464T, 2:465, 2:465T sequences, myoglobin 1:244–245, 1:246F Ammerla¨nder Knochenschinken 1:532–533 definition 1:530 Ammonia, as refrigerant 3:200 Ammonium chloride, hide deliming 1:119 Ammonium hydroxide, effect on waterholding capacity 1:280 Ammonium sulfate, hide deliming 1:119 Amplicon, definition 2:294 Amplification, definition 2:294 Anabolic–androgenic steroids see Anabolic steroids Anabolic implants effect on tenderness 3:268 see also Anabolic steroids Anabolic lipid metabolism 2:45–47 definition 2:43 de novo lipogenesis 2:45–47 Anabolic steroids cattle industry use 2:53 definition 2:62 see also Anabolic implants Anabolism, catabolism vs. 1:353 Anaerobes, definition 1:137 Anaerobic, definition 2:152, 2:289 Anaerobic digesters, manure 1:73, 1:74F, 2:154–155 Anaerobic digestion processes 2:160–161, 2:162F Anaerobic lagoons 2:154 Anaerobic metabolism, muscle fibers 1:155–156, 1:162F Anaerobic packaging, with blooming agents 3:23 Anaerobic spoilage, factors affecting 3:390–391, 3:391T Anaerobic treatment, manure 2:154 Analysis of variance (ANOVA), sample size 1:191 Analysis techniques, statistical requirements see Statistical requirements, analysis techniques Anaphylactic reactions, detrimental effects in humans of veterinary drug residues 3:65 Anchovy 3:337–339T nutritional content 3:336–342, 3:342T Andouille sausage 3:243 Androgen(s) in animal production 2:62 definition 2:62 growth gender effects 2:76 of muscle 2:65 pubertal 2:53 synthetic, growth stimulation 2:53 Androgenic, definition 2:62

467

Androgenic steroids skeletal muscle growth effects 2:78–79 see also Testosterone Androstenone as boar taint compound 1:98 control strategies development of genetic markers for low boar taint pigs 1:101–103, 1:102T effective dietary and management methods 1:100–101, 1:100F cutoff levels 1:98 factors affecting accumulation 1:98–99 sensitivity to 1:98 synthesis and metabolism 1:98, 1:99F Anemia, parasite-associated, goats 2:475, 2:476F Anemometers 3:54 calibration 3:56 types 3:54 laser Doppler anemometers 3:55 mechanical anemometers 3:54, 3:55F pilot tubes 3:54, 3:54F thermal anemometers 3:54–55, 3:55F ultrasonic anemometers 3:55 use, practical guidelines 3:55–56 Angiotensin-converting enzyme (ACE) 2:119 Angiotensin I-converting enzyme (ACE) inhibitory peptides definition 2:32 meat-protein derived 2:35 Angkak 1:523 definition 1:522 Angus cattle 3:329, 3:329F Animal(s), cloned see Cloned animals Animal behavior abnormal, as indicator of poor welfare 3:110–111 changes during domestication 3:360 domestication, traits for 3:357–358, 3:360 importance of 3:84 innate, definition 3:102 stereotypic see Stereotypic behavior using to explore animal welfare 3:111 see also Animal welfare, behavioral indicators Animal behavior, during handling and transport 3:84–89 abusive acts detrimental to welfare 3:87 animal perception 3:85–86 auditory effects 3:86 effects of smell 3:86 vision affects livestock movement 3:85–86, 3:96–97, 3:98F behavioral indicators of stress 3:84–85 eye white response 3:85 vocalization 3:84–85, 3:100 behavioral methods for moving livestock 3:86 flight zone 3:86, 3:97 point of balance 3:86, 3:97, 3:97F distractions that inhibit animal movement 3:90 beef plant (case study) 3:90 need and impact of understanding 3:87–88

468

Index

Animal behavior, during handling and transport (continued) impact of Temple Grandin’s work 3:87–88, 3:88T species differences 3:86–87 isolated lone animal problems 3:87 recommended driving aids 3:87 sizes of groups for movement cattle, pigs, goats, bison, and deer (small groups) 3:87 sheep (large groups) 3:86–87 use of electric prods 3:87 use of following behavior 3:87 stress during slaughter 3:85 Animal breeding, traditional 1:19–26 crossbreeding 1:20–21, 1:21F future considerations 1:25–26 genetic selection within breeds 1:21 genetic parameters for carcass composition and meat quality traits 1:19T, 1:20T, 1:21–22 major genes 1:13–14, 1:15T, 1:25, 1:25T selection programs see Genetic selection programs selection between breeds 1:19 carcass composition 1:19–20 meat quality 1:20 Animal by-products (ABPs) 2:158–159 biosecurity issues 1:126 categories 1:125, 1:125T, 2:158 category 1 material 2:158–159 category 2 material 2:159 category 3 material 2:159–160 definition 2:158 disposal and recycling 2:161 edible see Edible by-products fat reference data 1:127T as feed ingredients 1:129–130 future developments 1:136 handling, potential health risks 1:125T, 1:126 historical uses 1:125 industrial uses 1:129 inedible 1:126 see also Inedible meat by-products mineral matter 1:127T nutrient qualities 1:129–130 production rates 1:127 protein reference data 1:127T rendering see Rendering utilization regulations 1:125 water products 1:127T Animal casings, sausages see Sausage casings Animal conservation, cloning 1:90–91, 1:90F Animal-derived extender ingredients 1:5 Animal-derived fats 1:130 see also Fat Animal-derived nutraceuticals see Nutraceuticals Animal-derived proteins inedible 1:133–134 see also Protein(s) Animal disease traceability 1:483 see also individual diseases

Animal domestication see Domestication of animals Animal feed see Feed(s) Animal handling behavior during see Animal behavior, during handling and transport preslaughter see Preslaughter handling Animal health market specifications and 2:231–232 organic meat production 2:199 Animal health import risk analysis 1:27–32 consequence assessment 1:28, 1:31 entry assessment 1:28–29, 1:30F biological factors 1:29 commodity factors 1:29 country factors 1:29 processing effects 1:29 traceability 1:29 vaccinations 1:29 veterinary services evaluation 1:29 exposure assessment 1:28, 1:29–31 hazard identification 1:28 international obligations 1:28 qualitative methods 1:27–28 quantitative methods 1:27–28 risk assessment 1:28–29 risk communication 1:31–32 risk estimation 1:28, 1:31 transparency 1:27 uncertainty 1:27 variability 1:27 Animal health products injectable, beef quality assurance (BQA) guidelines 3:174, 3:175T see also Veterinary medicinal products (VMPs) Animal–human relationship see Human–animal relationship Animal listeriosis 2:351 Animal movement, behavioral aspects/ methods see Animal behavior, during handling and transport Animal origin and domestication 3:357–362 domestication see Domestication of animals origins 3:357, 3:358–359 cattle 3:358, 3:359 goats 3:359 pigs 3:360 poultry 3:360 sheep 3:359 wild animals, for domestication 3:358, 3:358T Animal production characteristics, market specifications 2:233 Animal products preservation see Preservation Animal rights animal welfare vs. 1:481 movement 3:109 Animal transmissible spongiform encephalopathies see Transmissible spongiform encephalopathies (TSEs) Animal welfare 1:481, 3:102–107, 3:108–113

abusive acts during handling/transport detrimental to welfare 3:87 animal rights vs. 1:481 approaches to understanding 3:109–110, 3:110F biological functioning 3:110 ‘nature’ of animals 3:110 subjective experience of animals 3:110 assessment 3:105, 3:112 animal-based measures 3:112 definition 3:108 health indicators 3:105 input vs. outcome-based criteria 3:105 management-based measures 3:112 definition 3:108 on-farm methods 3:112 physiological indicators 3:106, 3:106T production measures 3:106, 3:107F resource-based measures 3:112 definition 3:108 Welfare Qualitys project 3:112, 3:112T behavioral indicators 3:105, 3:105T, 3:111 abnormal behavior 3:105, 3:110–111 injurious behavior 3:105, 3:105T normal behavior, changes in 3:105–106 challenges to 3:104T codes of practice 3:103 consumers, importance to 3:102–103 definitions 1:480, 3:95, 3:95, 3:102, 3:109, 3:111 endemic diseases 3:104 ethical discussions, stereotypes 3:281, 3:281T exsanguination 1:562 feeding methods 3:105 five freedoms 3:102, 3:109 food safety 3:103 gas stunning concerns see Gas stunning housing conditions behavioral deprivation 3:104–105 food safety and 3:103 intensive systems 3:103–104 indicators 3:105 behavioral see behavioral indicators (above) lairage/lairaging and 3:99 legislation 3:103, 3:111–112 market specifications and 2:231–232 nutrition 3:105 physical environment, appropriate 3:104 pigs see Pig(s) poor 3:110 abnormal behaviors as indicators 3:110–111 pain and suffering 3:110 principles 3:102 production diseases 3:104 red meat production systems and 2:212 standards 3:103, 3:111–112 auditable 3:103 international 3:103, 3:111 stockmanship 3:103, 3:104T surgical procedures 3:103 threats to 3:103–105, 3:104T using animal behavior to explore 3:111 see also behavioral indicators (above)

Index

welfare continuum 3:110 what is good welfare? 3:111 see also Welfare issues Animal welfare science 3:109 Anoxia, definition 3:401 Ansbacher PreXsack, definition 1:530 Anserine 3:396 definition 3:394 as meat-based bioactive compound 2:34, 2:34F Antelope 3:345, 3:349 meat proximate composition 3:351T Antemortem inspection, pigs 3:297 Antibiotic(s) 2:412–413 in beef production 2:477 critically important, guidance documents 3:66 definition 1:480, 3:64 efforts to reduce use of 3:65 in human medicine see Antibiotic therapy, humans pigs 2:186–187 drugs to avoid 2:186 individual animal injections 2:186–187 routes of administration 2:186–187 resistance to see Antibiotic resistance sensitivity, Aeromonas 2:320–321 target vs. zoonotic pathogens 2:413 use in aquaculture, environmental contamination 2:418 use in livestock, policy issues 1:482–483 use in USA 2:109 see also Veterinary drug residue analysis Antibiotic growth promotants (AGPs) 2:172–176 allowed antibiotics 2:173–174 alternatives 2:172, 2:175 antibiotic resistance development 2:173 termination of use impacts 2:175–176 bans on use 2:173–174, 2:174, 2:174T, 2:175T definition 2:172 efficacy 2:172–173, 2:173F germfree animals 2:173 global use status 2:174, 2:175T managing without 2:176 mechanism of action 2:173 gastrointestinal microbiota changes 2:173 pigs 2:186 Antibiotic resistance 2:412–416 Aeromonas 2:320–321 antibiotic growth promotants and 2:173, 2:175–176 aquaculture 2:414 biofilm bacteria 1:67, 1:68–69, 1:69 Clostridium difficile 2:415 commensal bacteria 2:414–415 definition 2:172, 2:417 as detrimental effect of veterinary drug residues in humans 3:65 future perspectives 2:415–416 methicillin-resistant Staphylococcus aureus see Methicillin-resistant Staphylococcus aureus (MRSA)

monitoring 3:65 proper handling, storage, and cooking of food and 2:415 public concerns and policy issues 1:482–483 risk factors in humans 1:482–483 soil bacteria 2:417 travel considerations 2:415 zoonotic bacteria 2:413–414 Campylobacter 2:414 Salmonella 2:413–414 see also Antimicrobial-resistant bacteria transmission, wildlife/environmental contributions Antibiotic therapy, humans 2:413 listeriosis 2:351–352 Antidorcas marsupialis (springbok) meat 3:349, 3:351T Antihelmintic drugs 3:66 application (beef cattle) 3:66F definition 3:64 veterinary drug residues, detrimental effect in humans 3:66 Antimicrobial(s) chemical, processed meat decontamination see Processed meat, decontamination definition 3:173 used in meat processing/meat products 1:10 see also Antibiotic(s) Antimicrobial activity lactic acid bacteria see Lactic acid bacteria (LAB) smoke components 3:323 Antimicrobial intervention definition 2:276 see also Fresh meat, decontamination Antimicrobial residue, definition 2:417 Antimicrobial-resistant bacteria transmission, wildlife/environmental contributions 2:417–421 avian species 2:419–420 environmental exposure to antimicrobialresistant organisms 2:417–419 research needs 2:420–421 terrestrial animals 2:419 wildlife role 2:417, 2:418T Antioxidant(s) 1:10, 3:81, 3:396 addition to minced meats 2:424 dietary, warmed-over flavor prevention 1:413–414 as ingredients 1:300–301 natural curing 1:433 warmed-over flavor prevention 1:413, 1:414, 3:396 Antioxidant activity, smoke see under Smoking, traditional Antioxidant enzymes, muscle 3:399 Antlers, velvet see Velvet antlers AOAC International chemical standards and official methods on meat and meat products 1:197 methods recommended for nutritional analysis 1:169–170, 1:170T

469

Apoptosis 3:441 definition 2:405 Apparatus, patenting see Patents, examples of Apparent specific heat around freezing point 3:202–203, 3:203F definition 3:202 Appearance, meat beef quality and 3:333–334 effect of freezing 3:192–193, 3:193F effect of thawing 3:205 see also Meat color Appertization, definition 1:527 Applicability, definition 1:193, 1:194 Application model, refrigeration 2:436, 2:437F Appropriate Level of Protection (ALOP) 3:230 definition 3:226 Aquaculture antibiotic use, environmental contamination 2:418 antimicrobial resistance 2:414 finfish production 3:336, 3:340–341T, 3:421 systems 3:421 see also Farmed fish Aqui-STM 3:422–423 Arabian camel 2:193 Arcobacter butzleri 2:340–341 Arcobacter cryaerophilus 2:340 Arcobacter skirrowii 2:340 Argentina, national meat research institution 2:255–256T L-Arginine–nitric oxide pathway 1:436, 1:437, 1:440, 1:440F Argon, in gas stunning 3:402 aversion studies 3:403 mechanism of induction of unconsciousness 3:402 Aroma cooked meats desirable meaty aromas 1:381, 1:382F see also Volatile compounds dry-cured products 1:428, 1:428T raw meat 1:258 see also Odor(s) Aroma compounds measurement 3:278 see also Volatile compounds Aromatic compounds, dry fermented sausages 3:252, 3:254T Arterial pumping, brine 1:421–422 Artificial insemination cloned embryos vs. 1:89–90 pork quality 3:169 Artificial neural networks, definition 1:180 Artiodactyla (Order), definition 3:357 Ascomycetes 2:395 Ascorbates 1:419–420, 3:80–81 Ascorbic acid as reducing compound 1:298 as secondary antioxidant 1:414 Ascospores 2:395 Ash 1:242 content in meat, factors influencing

470

Index

Ash (continued) changes from birth to maturity 1:236, 1:236T fat content of meat 1:235, 1:236F species differences 1:237T see also Minerals Ashing 1:173 Asia livestock numbers 2:212T cattle 2:212T, 2:213, 2:213T pigs 2:212T, 2:216 sheep and goats 2:212T, 2:214 Southeast, meat products and cuisine 1:522–526 wet markets see Wet markets see also specific countries ASPCA (American Society for the Prevention of Cruelty to Animals) pen 3:212, 3:212F, 3:213 Aspergillus 2:395, 2:397F in meat 2:401 Aspergillus flavus, aflatoxin production 2:401, 2:402 Aspergillus oryzae, Oriental fermented foods 2:402 Aspergillus parasiticus, aflatoxin production 2:401, 2:402 Association of American Feed Control Officials 2002 Ingredient Manual, animal by-product listings 1:129–130 Astrogliosis definition 2:362 in transmissible spongiform encephalopathies 2:363 Atherogenesis 2:105 low-density lipoproteins and 2:105 Atheroma 2:105 Atlantic cod see Cod, Atlantic Atlantic salmon see Salmon, Atlantic At-line, definition 2:480, 2:489 Atmosphere, Clostridium botulinum control in meats 2:333 Atomic absorption spectrometry (AAS) 1:176 mineral analysis in meats 1:214 Atomic emission spectrometry (AES) 1:176 Atomization, liquid smoke 3:140, 3:141F ATP see Adenosine triphosphate (ATP) Attaching and effacing (A/E) lesions, enteropathogenic E. coli 2:358 Attachment, planktonic cells, biofilm formation 1:65T, 1:67 Attitudes, meat consumption 2:135, 2:136–137 Attribute, definition 2:218 Audit(s) definition 3:295 mechanical stunning, abattoirs 3:416 Auditing procedure, laboratory accreditation 2:148 Auditory effects, animal behavior 3:86 Auroch definition 3:357 origin of cattle 3:358 AUS-MEAT 2:232 definition 2:231

Australia antibiotic growth promotant policy 2:175T beef carcass classification/grading 1:311–313 Meat and Livestock Australia see Meat and Livestock Australia (MLA) meat research institutions national 2:255–256T provincial 2:257–261T Meat Standards Australia (MSA) grading program see Meat Standards Australia (MSA) grading program Austria, provincial meat research institution 2:257–261T Austronesian expansion, definition 3:357 Authentication definition 2:265 food/meat 2:265 EU systems see European Union (EU) see also Species determination (meat species) Automation cutting and boning see Cutting and boning, automation slaughter-line operation see Slaughter-line operation, automation Autoxidation, lipids 1:259–260 warmed-over flavor 1:411 a* value 2:40 definition 2:37 Average daily gain (ADG) bovine somatotropin administration 2:181–182 definition 2:181, 3:374 effects of breeds/genetics goats 3:375 sheep 3:375 ovine somatotropin administration 2:181–182 porcine somatotropin administration 2:182 Avian influenza low pathogenicity, imported poultry meat 1:29 surveillance 2:221 Avian influenza outbreaks ostrich industry 3:347 wet markets and 2:246 guidelines on handling and slaughtering poultry 2:246 Avian myoglobin 1:244–245 Avian species transmission of antimicrobial-resistant organisms 2:419–420 see also Bird(s) Avoparcin 2:173–174 aw see Water activity (aw) Ayrshire cure, bacon 1:59

B Baader meat 2:271 see also Mechanically recovered meat (MRM)

Bacilli, definition 2:289 Bacillus cereus 2:324–329 characteristics 2:324, 2:324F control and preventive measures 2:328 enterotoxins 2:324, 2:327 definition 2:324 epidemiology 2:327–328 foodborne/meatborne disease, characteristics 2:326–327 isolation and identification 2:325–326, 2:326T mechanism of pathogenicity 2:327 Bacillus cereus–Clostridium perfringens broth, Clostridium perfringens detection 2:311 Bacillus mycoides 2:325 Bacillus thuringiensis 2:325 Bacillus weihenstephanesis 2:325 Back bacon 1:446–447 Backslopping, Wiltshire bacon production 1:58–59, 1:61 Bacon 1:53–57 fungi occurrence 2:402T historical aspects 1:53–54, 1:58 precooked see Precooked bacon production procedure 1:446–447 quality, animal feed and 1:58 slice thickness 1:57, 1:57T in United States see Belly bacon Wiltshire see Wiltshire bacon Baconers 1:58 Bacon jerky 1:57 Bacon pigs 1:58 Bacteremia, definition 2:357 Bacteria acceptable ranges in food 2:400T antibiotic resistance see Antibiotic resistance Brownian movement, definition 1:64 commensal see Commensal bacteria Gram-negative see Gram-negative bacteria Gram-positive see Gram-positive bacteria growth influence of water activity 3:78–79, 3:78T see also Microbial growth growth retardation salt 1:296 sugars 1:297 nutrient competition 1:77 probiotic see Probiotic bacteria spoilage see Spoilage bacteria spore-forming see Spore-forming bacteria see also Biofilm(s); Indicator organisms; individual species Bacterial inhibition salt levels 3:79T see also Bacteria, growth retardation Bacterial spoilage see Spoilage Bacteriocidal, definition 1:76 Bacteriocins 1:10 application to meats 1:78–79 cooked meats 1:79, 1:79F fermented sausages 1:79 fresh meat 1:79–80

Index

processed meat decontamination 2:282–283, 2:291 definition 1:7, 2:280, 2:289, 2:340 as hurdle technology 2:346 lactic acid bacteria 1:77 antimicrobial activities 1:78 production 1:77–78 resistance 1:78 see also Nisin Bacteriophage(s) control of bacteria in meats 1:80–81 definition 1:80–81, 2:280, 2:283, 2:357 Escherichia coli O157:H7 2:358–359 infection 1:80–81, 1:80F processed meat decontamination 2:283 see also Phage typing Bacteriostatic definition 1:76 see also Bacteria, growth retardation Bactrian camel 2:193 Badisches Scha¨ufele, definition 1:530 Baird–Parker (BP) agar, Staphylococcus aureus enumeration and detection 2:314–315, 2:378–379, 2:378F Baleron 1:558 Banana bar, cattle hide removal 3:286–287 Bangers 3:246 Barbecue, North American see North American meat products Barker hypothesis (fetal origin of disease) 2:52 Barred Plymouth Rock 3:369, 3:369F Barrier properties, packaging material see under Packages Barrows (castrated male pigs) 3:363–364 boars vs. pork production 1:97–98 fat levels 2:76 see also Pig(s) Basal lamina, definition 2:75 Basidiomycetes 2:395 Basidiospores 2:395 Batch chilling systems 3:187, 3:187F Batch floor stunning systems 3:92 Batch ovens 3:131, 3:131F, 3:132F typical components 3:135F see also Cooking processes Bates 1:120 Bating, hides 1:119–120 Battering (coating) common terms 3:115–116 materials (batters) 3:116 production lines 3:114, 3:114F reasons for 3:114 Battering/breading equipment 3:114–122 coating materials 3:116 common line configurations 3:116 leavened systems 3:117–118 natural and formed products 3:116, 3:117F nonleavened systems 3:114F, 3:116–117, 3:118F common terms 3:115–116 early history and process goals 3:114–115, 3:115F examples of commonly coated substrates 3:115, 3:115T

key control points in performance of coating lines 3:121–122 measures of coating line performance 3:121 role of frying in coating systems 3:116 types of coating equipment 3:118 batter applicators 3:118, 3:119F batter mixers 3:118–119 breading applicators 3:119–120, 3:120F common design goals 3:121 conveyors 3:121 frying/cooking 3:120–121, 3:120F, 3:121F why substrates are coated? 3:114 Batters, meat 1:272, 1:272F, 2:422 definition 1:267, 1:283 emerging trends low-fat batters 1:287 low-salt batters 1:287 stability see Comminuted meat products, emulsion/batter stability see also Comminuted meat products; Emulsification; Meat emulsion(s) Bayerischer Leberka¨se, definition 1:530 Bayonne hams 2:88 definition 2:87 Bedika see Kosher slaughtering (shechita) Beef aging 1:335 carcasses see Beef carcass(es) cattle see Beef cattle Clostridium difficile contamination 2:341 Clostridium perfringens contamination 2:337–338 cold shortening 1:343 color, breed effects 3:334 concentrations of low-molecular weight soluble components 3:389T consumption, trends 2:477 consumption per capita (US) 2:248, 2:249F corned see Corned beef dark, firm, and dry meat see Dark-cutting beef (DCB) demand index (USA) 2:248–250, 2:250F Escherichia coli O157:H7 testing program 2:359 fatty acid composition 2:115F, 2:116, 2:116T flavor sensory assessment 3:276–277 unacceptable 3:277 French dishes, braised 1:527 ground see Minced beef Hanwoo see Hanwoo beef Kobe 1:543–544, 1:543F lean criteria/fat level 2:107 fat and cholesterol content 2:107, 2:108T, 2:112, 2:114T role in healthy diet 2:107 lean finely textured see Lean finely textured beef (LFTB) lipid content 2:114, 2:115F marbling 3:332, 3:333–334 breed effects 3:333–334

471

vitamin A effects 1:314–315 marbling to meat palatability relationship 1:254, 1:255T mechanically recovered composition 2:273, 2:273T safety 2:274 uses 2:272 minced see Minced beef Mycobacterium avium subsp. paratuberculosis (MAP) contamination 2:342 nutrient composition 3:371T off-flavor, selenium feeding 1:259 pale, soft, and exudative meat 1:343 prices, US 2:248, 2:249F production see Beef production quality see Beef quality safety, farm level see Beef safety and quality, farm level sensory assessment see Sensory assessment, meat stress-induced muscle degeneration 1:344 taste characteristics, biological type differences 3:334 tenderness, breed differences 3:334 texture, breed effects 3:334 vacuum packaging 3:31 larger cuts 3:31 warmed-over flavor analysis 1:411–412 zinc source 2:126 see also Beef cattle; Cattle Beef carcass(es) chilling see Carcass chilling classification see Beef carcass classification/ grading cleaning, automation 1:48 cutability 3:333 cutting/boning 1:459 automation see Cutting and boning, automation bottom sirloin 1:461 forequarter boning 1:459–460 forequarter cutting 1:459 forequarter subprimals 1:459 hindquarter boning 1:460 hindquarter cutting 1:460 hindquarter subprimals 1:460 strip loin 1:461 tenderloin 1:461 top sirloin 1:461 variation in boning 1:143T wholesale cuts 1:459, 1:459F dressing percentage see Dressing percentage, cattle electrical stimulation 1:145 grading see Beef carcass classification/ grading hot boning 1:455 hurdle technology 3:289 lactic acid sprays 3:289 opening, automation 1:47–48 organic acid use 3:289 splitting, automation 1:48 thermal center 3:179 trimming see Trimming see also Cattle, carcass composition; Cattle slaughter process

472

Index

Beef carcass classification/grading 1:307–315 Australia 1:311–313 automation 1:48 Europe 1:307–309 Japan see Japan purpose of 1:307 United States 1:309–311, 1:459 see also individual grading systems Beef cattle 3:328–335 biological types 3:328–331 cutability 3:333 meat quality and 3:332 meat taste differences 3:334 bull comparisons 3:331 carcass composition see Cattle, carcass composition carrying capacity of pastures, factors affecting 2:477, 2:477T commercial beef animal value, traits determining 3:332 beef quantity 3:332 meat quality 3:333–334 conformation 3:333 crossbreeding 3:330–331 differences in carcass composition among breeds 1:19–20 double muscling see Double-muscled animals; Double muscling fatness 3:332 carcass weight 3:332 feedlot 2:477 water requirement, calculation 2:479, 2:479T feedstuffs, beef quality assurance (BQA) program 3:174, 3:175T finished, important traits 3:331 finishing beta-agonists as feed additives 2:477 Optaflexxs 2:179 Zilmaxs 2:179 total mixed ration 2:109 genetic improvement programs 1:24–25 use of imaging techniques 1:23 see also Genetic selection programs hides dressing percentage 3:332–333 see also Cattle, hides hybrid breeding 3:330–331 intestines, as sausage casings 1:110, 3:237, 3:237F live weight 3:332 mature body size 3:331 muscle distribution 3:331 muscularity 3:331 carcass weight 3:332 nutritional requirements, factors affecting 2:477, 2:478T organic systems 2:109, 2:201 propensity to fatten 3:331–332 slaughter process see Cattle slaughter process temperament 3:331 see also Beef production; Cattle Beef Chuck, Chuck Roll (IMPS 116A) 1:460 Beef Chuck, Shoulder (Clod) (IMPS 114) 1:460

Beef Chuck, Shoulder (Clod), Arm Roast (IMPS 114E) 1:460 Beef Chuck, Shoulder (Clod), Top Blade (IMPS 114D) 1:460 Beef Chuck, Shoulder Tender (IM) (IMPS 114F) 1:460 Beef Color Standard (B.C.S.), Japan 1:313, 1:313F, 1:314T Beef Fat Standard (B.F.S.), Japan 1:314, 1:314F, 1:314T Beef in an Optimal Lean Diet (BOLD) study 2:105, 2:106–107 Beef Loin, Strip Loin, Boneless (IMPS 180) 1:461 Beef Loin, Tenderloin, Full Side Muscle On, Defatted (IMPS 189A) 1:461 Beef Loin, Top Sirloin Butt, Boneless (IMPS 184) 1:461 Beef Marbling Standard (B.M.S), Japan 1:312F, 1:313, 1:313T scores for Japanese Black cattle 1:231–232, 1:231F Beef plant, distractions that inhibit animal movement (case study) 3:90 Beef plate, cooked sausage processing 3:241–242 Beef production 2:477–478 extensive suckler 2:201 global 1:502, 1:502F indigenous 2:215T organic 2:201 see also Beef cattle; Cattle production systems Beef quality 3:333–334 appearance factors 3:333–334 definition 3:173 eating quality 3:334 impact of beef quality assurance 3:174–176 improvement, application of genomic technologies 2:37–38 meat quality measurement marbling 2:493–494 mechanical measurement of toughness 2:494–495 see also Beef safety and quality, farm level Beef quality assurance (BQA) program 3:173, 3:173 Code of Cattle Care 3:176–177 goals 3:173–174 guidelines 3:174, 3:175T care and husbandry practices 3:174, 3:175T feed additives and medications 3:174, 3:175T feedstuffs 3:174, 3:175T injectable animal health products 3:174, 3:175T processing/treatment and records 3:174, 3:175T history 3:173 impact on product quality 3:174–176 producer certification 3:176, 3:177 Beef Ribeye, Lip-On (IMPS 112A) 1:459–460

Beef Round, Bottom (Gooseneck) (IMPS 170) 1:461 Beef Round, Eye of Round (IM) (IMPS 171C) 1:461 Beef Round, Outside Round (Flat) (IMPS 171B) 1:461 Beef Round, Sirloin Tip (Knuckle), Peeled (IMPS 167A) 1:460–461 Beef Round, Top (Inside) (IMPS 168) 1:461 Beef safety and quality, farm level 3:173–177 beef quality assurance program see Beef quality assurance (BQA) program definition of beef quality 3:173 producers’ role 3:176 Code of Cattle Care 3:176–177 continual improvement 3:176, 3:176T self assessments 3:176 Beef salami 3:243 Beef sausage, fresh see Fresh sausage Beer flavoring, warmed-over flavor prevention 1:414 Beer salami 3:243 Behavior, animal see Animal behavior Beijing-style flavor, traditional Chinese meat products 1:524 Belgian Blue cattle, double muscling genetics 1:465–466, 1:466 see also Double-muscled animals; Double muscling Belgium, provincial meat research institution 2:257–261T Belly(ies) definition 3:241 pigs see Pork bellies Belly bacon 1:53 color 1:57 consumption 1:53 cooking 1:56 curing methods 1:55–56 drip time 1:56 injection 1:55–56 dry-curing 1:56 flavor development 1:57 historical aspects 1:53–54 immersion curing 1:56 microbiology 1:57 packaging 1:57 post-cook chilling 1:56 pressing/forming 1:57 production 1:55F raw materials 1:54–55 slicing 1:57 smoking 1:56, 1:56 tempering 1:56–57 Belt–drum systems, mechanical meat recovery 2:271 Belt dryers 1:475, 1:475F Belt grill cooking 1:374 Belt ovens 3:133, 3:133F, 3:134F see also Cooking processes Benecols margarine 2:453 Bentham, Jeremy 3:108–109 Benzo(a)pyrene (BaP), in smoked foods 3:324 maximum residual amounts 3:223

Index

Berkshire breed, pigs, pork quality 3:169 Berliner bologna 3:243 Best linear unbiased prediction, definition 1:19 Beta-adrenergic agonists (BAA) 2:66–68, 2:177–180 adipose tissue reduction 2:67–68 in animal production/as feed additives 2:66–68, 2:178–179, 2:468 administration 2:67 animal maturity and 2:68 approved products 2:177 dosages 2:67 effects 2:67T mechanism of action 2:67–68, 2:179 practical considerations 2:68 safety 2:179–180 species response differences 2:67, 2:67T see also Beef cattle, finishing characteristics 2:177–178 classification 2:67 definition 2:62, 2:181 lipolysis 2:47 meat tenderness 2:68 muscle growth 2:67 as partitioning agents 2:67 as repartitioning agents 2:67 somatotropin and, additive effects 2:182 steroids and, comparative efficacy 2:68 structure 2:177, 2:177F synthetic 2:177, 2:178F b1 vs. b2 agonists 2:67T, 2:68 b1-agonists, effects 2:67, 2:67T b2-agonists, effects 2:67, 2:67T see also individual agonists Beta-adrenergic receptors (b-AR) 2:67 thermogenesis 2:44 Beta-hemolysis see Hemolysis Bezoar, domestic goat progenitor 3:359 Bicoid, embryonic growth 2:50 Bierwurst 3:243 Bile acids, as animal-derived nutraceuticals 2:131 Biltong 1:515–517 commercialization 1:516–517 definition 1:515 history 1:515 preservation, storage, and shelf life as intermediate moisture food 1:516 traditional method of making 1:515–516 see also Dry curing Bimetallic thermometers 3:60 Binary toxin, definition 2:340 Binders 1:1–2, 1:2, 1:299–300, 3:81 definition 3:78 see also Extenders Binding agents, natural curing 1:433 Bioactive compounds, meat-based see Functional food(s) Bioactive peptides 2:119 antihypertensive activity 2:119 definition 2:118 physiological effects 2:119 released during beef digestion 2:119, 2:120T see also Carnosine; Glutathione

Bioavailability, definition 2:124 Biocidal, definition 2:289 Biodigestors definition 1:71 manure 1:73, 1:74F, 2:154–155 Biodiversity, impact of meat production 1:503 Biofilm(s) 1:64–70 antimicrobial resistance 1:67, 1:68–69, 1:69 cellular control, role of cell-to-cell signaling molecules 1:67–68 definition 2:348 in food industry 1:68–70 prevention/control 1:69 processing equipment and 1:68, 1:513 formation see Biofilm formation studying 1:68 Biofilm formation 1:64 molecular basis 1:67–68 stages of process 1:64, 1:65T, 1:66F production of exopolymeric substances, irreversible attachment, and development of biofilm architecture 1:65T, 1:67 surface conditioning 1:64, 1:65T, 1:66F transport of planktonic cells to surfaces and adhesion 1:64–67, 1:65T Biofuel(s) animal by-product use 1:126, 1:129 industry, interaction with 1:484 Biogas production anaerobic digestion processes 2:154–155, 2:160 see also Biomethane production and cleanup Biogenic amines 3:221–223 definition 3:221, 3:221 in dry fermented sausages, preventive measures 3:254 formation in foodstuffs 3:221, 3:222T raw sausages 3:222 in raw fermented sausages 3:222, 3:222T formation 3:222 tyramine as indicator 3:222 toxicological effects 3:222T Biological functioning, animal welfare and 3:110 Biological organisms, irradiation effects 2:143 Biological type, definition 3:328, 3:329 Biomethane production and cleanup 1:71–75 manure management to reduce methane emission and using techniques to generate energy 1:73–74, 1:74F methane production in livestock 1:71–72 factors related to methane production in ruminants 1:72–73, 1:72F additives 1:73 animals 1:72–73 diet components 1:73 modifiers 1:73 see also Manure management Biopreservation 1:76–82, 3:82

473

bacteriophage control of bacteria in meats 1:80–81 consumer acceptance 1:81 definition 1:76 patenting and 3:47 Biosecurity animal by-product disposal 1:126 external measures 3:170 internal measures 3:170 pork quality 3:170 Biot modulus 2:438 Biowaste management see Waste management, Europe Bird(s) game see Game birds listeriosis 2:351 management, intensive chicken meat production systems 2:209–210 production systems chicken meat see Chicken meat production systems exotic species 2:191–192 wild, transmission of antimicrobialresistant organisms 2:419–420 see also Poultry Biryani 1:540 definition 1:538 Bison (Bison bison) 3:291, 3:353–354 behavior during handling and transport see Animal behavior, during handling and transport farming 3:353 meat composition 3:353–354 Biting action, mechanical methods of tenderness measurement 3:455T, 3:456F Bitter basic taste, meat 1:259 Bivalves 3:383 Black Forest ham see Schwartzwa¨lder Schinken (Black Forest ham) Black metal, as surface in food production environments/equipment 1:509T Black pudding definition 1:527 French 1:529 see also Blood sausage Black scraping, pig carcasses 3:299–300 Black spot 2:401 Bladder cancer 2:102 Blade tenderization 3:447, 3:448F Blast coolers 3:206–207 Blastomere separation 1:84, 1:85F Blatwurst 3:246 see also Blood sausage Bleeding see Exsanguination Blenders mixers vs. 3:126 ribbon 3:127, 3:127F see also Mixing equipment Blending, cure application 1:446 Bloat 2:478–479 Blonde d’Aquitaine cattle 2:233, 3:330, 3:330F Blood, as edible by-product 1:110–111 Blood and tongue sausage 3:246

474

Index

Blood clots, food safety implications and detection 2:22, 2:22T Blood meal 1:134 Blood proteins 1:292 Blood sausage 3:246 French 1:529 German 1:536–537, 3:246 Thu¨ringer Rotwurst see Thu¨ringer Rotwurst Korean-style (sundae) 1:547F, 1:548 Blood splash see Petechial hemorrhage Blooming 3:14 definition 3:1, 3:13, 3:19, 3:26 fresh meat color 3:27–28 see also Myoglobin oxygenation; Oxymyoglobin Blooming agents, anaerobic packaging with 3:23 Blue crab 3:382T, 3:383F Blue mussel 3:384 Blue prawn 3:380F Boar(s) carcass composition 3:363–364 castrated male pigs vs., pork production 1:97–98, 3:363 odor 1:260, 1:302 see also Pig(s) Boar taint 1:97–103 chemical analysis 2:495 control, alternatives to castration 1:99–100 control strategies 1:100–101 development of genetic markers for low boar taint pigs 1:101–103, 1:102T effective dietary and management methods to control skatole and androstenone 1:100–101, 1:100F immunoneutralization 1:101, 1:101T definition 2:489 description and causes 1:98 see also Androstenone; Skatole detection methods 1:100 definition 1:97 factors affecting accumulation of boar taint compounds 1:98–99 use of tainted meat 1:99–100 Bockwurst 3:246, 3:259, 3:264 additives/seasonings 3:263T definition 3:261 finished form 3:265T processing 3:265T Body condition score (BCS), pigs 3:171 Body mass index (BMI), vegetarianism and 2:138 Boer goat 2:195, 3:375 see also Goat(s) Boiling, meat 1:373 ‘Boiling test,’ boar taint 1:100 Bologna 1:449, 3:243, 3:259 definition 1:555 formulation sheet 1:449T Lebanon bologna 1:556 spices used 1:306T Bone(s) carcass see Carcass bone density, breed differences 1:164–165 feather see Feather bones

formation 1:163, 1:165F Bone, contamination with 2:22, 2:22T detection 2:25, 2:25F, 2:26F see also Foreign bodies Bone growth abnormal 2:81 endocrine effects 2:80–81 form/function 2:80 age effects 2:80 gender effects 2:80 metabolic effects 2:76–77 nutritional effects 2:80–81 patterns 2:57–58, 2:57F physiology 2:80 cattle 2:76 puberty 2:80 somatotropin effects 2:77T, 2:80–81 steroid hormone effects 2:66 Bone-in hams 1:447 smoked, cooking process 3:136, 3:136T see also Ham(s) Bone-in injectors 3:123, 3:123F see also Brine injectors Boneless hams see Ham(s), boneless Bone marrow color, effects of meat packaging atmosphere 3:11 Bone morphogenic protein 2, embryonic growth 2:50 Bone separators, mincers/grinders 3:128–129, 3:128F Boning see Cutting and boning Bos indicus see Zebu cattle Bossam (Korean dish) 1:547F, 1:548 Bos taurus(Bos taurus taurus), definition 1:235 Botrytis 2:395, 2:398F ‘Botulinum cook’ process 2:333 Botulinum neurotoxin 2:330, 2:331–332 Botulism 2:330–334 diagnosis 2:330, 2:331 foodborne 2:330 incidents involving meat products 2:332 historical aspects 2:330 incidence 2:330 infant 2:330 symptoms 2:330 wound 2:330 see also Clostridium botulinum Boudin blanc 1:529 Boudin noir 1:529 Bovine, definition 1:235 Bovine growth hormone (bGH) see Bovine somatotropin (bST) Bovine respiratory disease (BRD), treatment 2:412–413 Bovine somatotropin (bST) 2:181–185 administration patterns 2:182 amino acid availability/composition and 2:182 animal health and 2:183–184 average daily gain 2:181–182 carcass quality 2:181–182 cooking loss 2:184 feeding level interactions 2:182 feed intake effects 2:182 growth response variations 2:182

historical aspects 2:181 meat collagen content 2:184 meat color 2:184 meat juiciness 2:184 meat quality 2:184 muscle characteristics 2:78, 2:184 optimal dose 2:182 performance 2:181–182, 2:183T routes of administration 2:181 steroid hormones and 2:68 Bovine spongiform encephalopathy (BSE) 2:20, 2:219, 2:362, 2:363–364 definition 2:231, 2:270 diagnosis 2:364 market specifications and 2:233 mechanical recovery of meat and 2:271, 2:274 outbreaks 2:362, 2:363 impacts 2:362, 2:364 prevention and control measures 2:219, 2:364 genetic engineering of animals 1:94–95 symptoms 2:363 Bowl choppers 3:129, 3:129F, 3:257F with additional features 3:129 vacuum hood 3:129, 3:129F Boxed beef program 3:30 Brachygnathia inferior double-muscled animals 1:467 Brachygnathia superior double-muscled animals 1:467 Brahman cattle, muscles, Warner–Bratzler shear force values 2:37–38 Brains, as edible by-products 1:108–109 Braised meats French see French meat products and dishes traditional Chinese meat products 1:524T, 1:525 Braising 1:373 Bratwurst 3:246, 3:264 additives/seasonings 3:263T cooked (white hots) 3:260 finished form 3:265T Nu¨rnberger see Nu¨rnberger Rostbratwurst/ Nu¨rnberger Bratwurst processing 3:265T Braunschweiger 3:243, 3:259 Braunschweiger Mettwurst, definition 1:530 Brazil antibiotic growth promotant policy 2:175T meat research institutions national 2:255–256T private industrial 2:262–263T Brazil and South America 1:518–521 cattle production systems 2:214 miscellaneous products 1:520 chunchul 1:520 prieta/morcilla 1:520–521, 1:520F regional products 1:518 dried meats 1:518 carne de sol 1:518 cecina 1:518–519 charqui 1:519, 1:519F sausages 1:519

Index

butifarra 1:519 linguic- a 1:519, 1:519F, 1:520F, 3:245 longaniza 1:519–520, 1:520F salchicha de huacho 1:520 Bread, Hawawshy see Hawawshy bread Breading 1:300 common terms 3:115–116 equipment see Battering/breading equipment materials 3:116 production lines 3:114, 3:114F reasons for 3:114 Breakfast sausage 3:261, 3:264 Breast cancer 2:103 Breathlessness causes 3:403 definition 3:401 Breeding, animal see Animal breeding, traditional Breeding value definition 1:12 estimated see Estimated breeding value (EBV) genomic, definition 1:12 Bresaola della Valtellina 1:551 Brine concentration calculation 1:296 microorganisms, influence on 1:296 definition 1:416, 3:123 flavoring ingredients 1:305 live see Live brine multineedle injection 1:422 cooked ham production 2:83–84 preparation 1:420–421, 1:445 cooked ham production 2:83–84 Brine-cured meats smoking, cooking, and drying 1:422–423 sodium reduction 1:423 Brine-cured products, salt levels 1:297 Brine curing 1:416–424, 1:445–446 hides 1:115–116 process 1:420 critical control factors 1:423 techniques 1:421 arterial pumping 1:421–422 massaging and tumbling 1:422 see also Massaging; Tumbling multineedle injection see Brine, multineedle injection pickle curing 1:421, 1:421T pickle injection 1:421 smoking, cooking, and drying of brinecured meats 1:422–423 stitch and spray pumping 1:422 see also Brine injectors see also Cooked ham production; Curing; Wiltshire sides Brine injectors 3:123–125 accumulator tanks 3:125, 3:125F definition 3:123 continuous injectors 3:123–124, 3:123F, 3:124F needles 3:124, 3:124F injection time 3:124 maintenance and sanitation 3:125

needle design 3:124 product temperatures 3:125 pump pressure 3:124 pumps 3:124–125 solution uptake targets 3:124 see also Brine curing Brine tanks, Wiltshire bacon production 1:58–59 British cattle 3:329 propensity to fatten 3:332 see also Cattle British fresh sausage, yeasts in 2:398 British Retail Consortium (BRC) Global Standard 3:164 Brochothrix thermosphacta, enumeration media 2:308–309 Broiler(s) 2:204F, 3:369–370, 3:370F antibiotic growth promotants efficacy 2:172–173 managing without 2:176 definition 2:204 genetic background, 1957 vs. 2001 3:369, 3:370F production see Chicken meat production systems slaughter see Poultry, slaughter-line operation stocking density–profit potential relationship 3:106, 3:107F see also Chicken(s); Poultry Broiler stunning definition 3:303 see also Stunning, poultry Broiling 1:373 Bromelain, as meat tenderizer 1:301, 3:441 Bromochlorotrifluoroethane see Halothane Bronchoconstriction, definition 3:401 Bronchothrix thermosphacta 3:391, 3:391–392, 3:391T Brooding, definition 2:204 Brown adipose tissue (BAT) 2:43–44 adipocytes 2:43 definition 2:43 development molecular mechanisms regulating 2:44 skeletal muscle similarities 2:44 newborns 2:43 thermogenesis 2:43 master regulator 2:43–44 Brown and serve sausage 3:246 Brownian movement, bacteria, definition 1:64 Browning Maillard see Maillard browning premature see Premature browning (PMB) BSE see Bovine spongiform encephalopathy (BSE) Bubalus arnee (wild buffalo) 2:192, 3:355 Bubalus bubalis (domestic buffalo) see Water buffalo Buccinum undatum 3:385 Buck, definition 2:190 Buddhism 3:282 Buffalo North American 3:291 production systems 2:192–193

475

slaughter process 3:291 water see Water buffalo Buffalo hide, by-products 1:113T Buffalo meat 3:354–356 Buffalo wings 1:557 Buffering capacity, meat 1:262–263 Buffers see pH buffers Bulgogi (Korean dish) 1:546, 1:546F Bulk density 3:460–461 Bulk density theory, meat tenderness 1:253 Bull(s) assessment 3:331 dairy cattle 3:330, 3:330F stunning considerations 3:415, 3:415F Bull calves 2:477 see also Veal Bull meat, French braised meat dishes 1:527 Bundle forming pili, enteropathogenic E. coli 2:358 Bung, definition 1:43 Bung dropping/bunging cattle slaughter process 3:288 automation 1:47, 1:48F pig slaughter process 3:300 Bushmeat definition 3:345, 3:345–346 economics 3:346 production 3:346 Bushpig (Potamochoerus larvatus) 3:352 Butcher shops, thermotolerant Campylobacter control 2:386–387 Butifarra 1:519 Butt cooked sausage production 3:241–242 definition 3:241 Butylated hydroxyanisole, warmed-over flavor prevention 1:413 Butylated hydroxytoluene, warmed-over flavor prevention 1:413 tert-Butylhydroquinone, warmed-over flavor prevention 1:413

C Cabinet dryers 1:474–475, 1:474F Cabrito, definition 3:374 Cadaverine 3:221 in raw fermented sausages 3:222, 3:222T toxicological effects 3:222T Calamari 3:386 Calcidiol 2:133–134 Calcitonin, bone growth 2:80–81 Calcitriol 2:133–134 Calcium mechanically recovered vs. hand-boned meat poultry 2:272–273 red meat 2:273, 2:273T nutritional enhancement of meat products 2:452, 2:453T Calcium-activated tenderization injection of calcium 1:336, 3:432, 3:434–435T

476

Index

Calcium-activated tenderization (continued) nonenzymatic tenderization 3:436–437 see also Tenderizing mechanisms, chemical Calcium ions, muscle contraction role 1:358–359, 1:360, 1:361F Calcium requirements, poultry 2:464T, 2:465 Calf see Calves Calibration anemometers 3:56 definition 1:316 hygrometers 3:52–53 online instruments, pig carcass classification 1:319 pH measurements 1:265–266 thermometers see Thermometers Calibration standard, definition 1:217 Caliciviruses 2:391 classification 2:391, 2:392F disease 2:391 survival in food 2:393 virus characteristics 2:391 zoonotic transmission 2:391–393 Callipyge/callipyge condition 1:466 definition 1:465, 3:374 effect on meat aging 1:334–335 see also Double-muscled animals; Double muscling; Muscle hypertrophy Callipyge gene (CLPG) 1:14, 1:15T, 1:25T, 1:466 mode of inheritance 1:344 sheep phenotype 1:344 Callipyge sheep 1:344, 1:466, 2:60 definition 2:56 Calpain(s) 1:215 analysis in meats 1:215 definition 1:274, 1:329, 1:486, 3:267, 3:438 effect of electrical stimulation on activity 1:494–495 effect on water-holding capacity 1:280–281 enzymes 3:439–440 inhibition 1:331, 3:440 see also Calpastatin integrins and 1:281 meat aging role 1:331 biochemical factors influencing 1:334, 1:334F see also Aging, meat meat tenderization role 3:432, 3:432–433, 3:433, 3:436, 3:439–440 application of genomic technologies in beef and 2:37–38 calpastatin and 3:440–441, 3:440F proteomic studies 3:156 see also Tenderizing mechanisms, chemical Calpain gene 1:13, 1:15T, 1:25T Calpastatin(s) 1:331, 3:440 callipyge lambs 1:344 definition 3:438 meat tenderness/tenderization and 1:331, 2:68, 3:440–441, 3:440F application of genomic technologies in beef 2:37–38

Calpastatin gene 1:13, 1:15T, 1:25T Calves bull 2:477 femur, structure 1:165F weaned, feeding 2:477–478 weaning 2:477 see also Veal Camel(s) meat composition 3:354, 3:355T consumption taboos 3:354 production systems 2:193 slaughter process 3:291 Camelids 3:354 meat fatty acid composition 3:355T production systems 2:193 Camelus bacterium (two-humped Bactrian camel) 3:354 Camelus dromedarius (one-humped dromedary) 3:354 Camphechlor (toxaphene) 1:497–498 CAMP test definition 2:306 Listeria 2:314 Campylobacter 2:340, 2:382 antimicrobial resistance 2:414 detection/enumeration 2:311, 2:312T human infection see Campylobacteriosis incidence in animals and meat 2:18 plating procedures 2:313–314T pre-/enrichment procedure 2:313–314T thermotolerant see Thermotolerant Campylobacter Campylobacter coli 2:382 antimicrobial resistance 2:414 human infection 2:17 identification 2:383T see also Thermotolerant Campylobacter Campylobacteriosis 2:17–18, 2:382 characteristics 2:384 epidemiology 2:384–385 pathogenesis 2:384 preventive measures see Thermotolerant Campylobacter, control measures symptoms 2:17–18 see also Thermotolerant Campylobacter Campylobacter jejuni 2:382, 2:414 antimicrobial resistance 2:414 human infection 2:17 identification biochemical reactions 2:383T multilocus sequence typing analysis 2:383–384 see also Thermotolerant Campylobacter Campylobacter lari 2:382 identification 2:383T see also Thermotolerant Campylobacter Canada antibiotic growth promotant policy 2:175T game production 3:346 meat research institutions national 2:255–256T provincial 2:257–261T nitrite regulations 1:418, 1:443 Canadian-style bacon 1:446–447

Cancer 2:100–104 bladder 2:102 breast 2:103 colorectal see Colorectal cancer concerns 2:100–104 development 2:100 diet and 2:101 endometrium 2:102–103 esophageal 2:101–102 etiological factors 2:101 incidence 2:100 kidney 2:102 lung 2:102 meat consumption and 2:101, 2:122–123, 2:447 mechanisms 2:122–123, 2:122F nitrate/nitrite association 1:436 see also Nitrosamines pancreatic 2:102 prostate 2:103 sites 2:101 stomach 2:102 see also Carcinogenesis Candidate genes 2:40 Cane rats 2:196 Canned bacon 1:57 Canned meat products 1:139 Canning 1:137–141, 3:81 heat and mass transfer during 1:139, 1:385 thermal properties of meat systems and 1:139 implications for meat quality 1:140–141 meat canning operations see Canning operations microbial populations and process severity 1:137–138 thermal resistance of microorganisms 1:138 expected shelf life and 1:138–139 meat physicochemical characteristics and 1:138 Canning operations 1:139 can filling 1:139 exhaustion 1:139 heat treatment 1:137, 1:139–140, 1:385 inactivation parameters 1:140, 2:432, 2:433F D- and z- values 1:140 F-value 1:140 heat treatment reduction, salt use 1:297 Cantonese cuisine 1:523F, 1:524 Capacitance hygrometers 3:51 Capillary electrophoresis, meat species determination 2:266 Capillary zone electrophoresis (CZE), amino acid analysis 1:211 CAPTECH chamber snorkel machines 3:6–7, 3:7F, 3:18 Captive-bolt stunning devices cattle stunning 3:284–285 types 3:413 see also Mechanical stunning Capture (wild) production, finfish 3:336, 3:337–339T Capybara 2:196 Carabeef see Water buffalo meat

Index

Caraboa meet see Water buffalo meat Carawaywurst (Kuemmelwurst) 3:245 Carbohydrate digestion, ruminants 2:474, 2:474F, 2:474T Carbohydrates, in meat 1:206, 1:241–242 levels 2:111 see also Glycogen Carbon, activated, boar taint control 1:100–101, 1:100F Carbon dioxide 1:502 cryogenic refrigeration 3:181 emissions, livestock production-related 1:505, 1:505F see also Greenhouse gases in gas stunning aversion studies 3:403, 3:403F gas mixtures 3:402 mechanism of induction of unconsciousness 3:402 meat packaging role 3:11 microorganism inhibition 1:301 secondary refrigeration systems 3:201 ‘snow’ 3:181 Carbon monoxide meat color effects 3:15 meat packaging role 3:11 Carbonyl(s), definition 3:315 Carbonyl-containing volatiles, flavor aromatics 1:258 Carboxymyoglobin 3:15 definition 3:9, 3:13 in packaged fresh meats 1:246–248, 1:246F, 1:247T see also Myoglobin Carcass(es) beef see Beef carcass(es) boning see Cutting and boning chilling see Carcass chilling classification see Carcass classification composition see Carcass composition contamination definition 3:290 see also Fresh meat, microbial contamination decontamination 2:287–288 apparatus for antimicrobial treatment, patenting 3:48 hurdle technology 2:346 see also Fresh meat, decontamination definition 3:290, 3:295, 3:328, 3:332 dressing see Dressing (carcass) freezing see Freezing, carcasses goats see under Goat(s) grading beef carcasses see Beef carcass classification/grading definition 1:307 pig carcasses 3:301 sheep/lamb carcasses 3:312–313 automation 1:52 growth, patterns 2:57, 2:58F see also Growth patterns hot boning see Hot boning injection point damage 3:65F lamb see Lamb carcass(es) market specifications 2:233

markings for identification, patenting 3:48 muscle-to-bone ratio see Muscle-to-bone ratio pig see Pig carcass(es) poultry see Poultry carcasses quality see Carcass quality splitting see Carcass splitting weight see Carcass weight yield see Dressing percentage Carcass bone 1:149T, 1:163–165 proportions 1:164–165, 1:166T see also Bone Carcass chilling 1:142–147 beef carcasses 1:144–145, 1:145–146, 3:289 delayed chilling 1:145 rapid chilling 1:142T, 1:145 spray chilling 1:146, 3:289 variation in chilling 1:142T, 1:143T pig carcasses see Pig carcass(es) poultry carcasses see Poultry carcasses principles 1:144–146 sheep/lamb/goat carcasses 1:146, 3:313 see also Chilling Carcass classification beef see Beef carcass classification/grading definition 1:307 patenting of process 3:47 pigs Europe see Pig carcass classification, Europe US 3:364–365, 3:364F sheep, automation 1:52 Carcass composition 1:148, 1:149F, 1:149T bone see Carcass bone cattle see Cattle, carcass composition definition 3:374 differences among breeds 1:19–20 fat see Carcass fat genetic improvement role of molecular markers 1:12–13 see also DNA markers selection programs 1:23, 1:23F genetic parameters 1:19T, 1:21–22 major genes 1:13–14, 1:15T, 1:25T quantitative trait loci see Quantitative trait loci (QTL) goats see Goat(s), carcass composition muscle see Carcass muscle pigs see Pig carcass, composition sheep see Sheep, carcass composition Carcass fat 1:149T, 1:157–163 distribution 1:159–160 cattle 1:165F pigs 1:152, 1:154F sheep 1:164F see also Intermuscular fat; Intramuscular fat; Subcutaneous fat pigs see Pig carcass, fat red deer stags 1:158–159, 1:164T see also Adipose tissue; Fat Carcass methods, meat tenderization see Tenderizing mechanisms, mechanical Carcass muscle 1:148–149 anatomy 1:149, 1:150F, 1:151F

477

distribution (in cattle) 1:149, 1:152F see also Connective tissue; Muscle; Muscle fibers Carcass quality cattle, bovine somatotropin and 2:181–182 definition 3:374 double-muscled animals 1:467T, 1:468–469 exsanguination and 1:563 goats see Goat(s), carcass quality pigs, porcine somatotropin and 2:182–183 poultry, nutrition and 2:469 sheep see Sheep, carcass quality see also Carcass composition; Meat quality Carcass splitting cattle, automation 1:48 patenting of apparatus 3:47–48 pigs 3:300–301 Carcass weight cattle fatness and 3:332 muscularity and 3:332 definition 2:190 hot vs. cold weight 3:332 Carcass yield see Dressing percentage Carcinogenesis definition 2:100 iron role 2:121 meat consumption and 2:122–123, 2:447 heme iron and nitrosation 2:122–123, 2:122F meat processing 2:101, 2:102, 2:103 process of, cancer development 2:100 see also Cancer Carcinogens, cooking forming 2:101, 2:447 Cardiac arrest, definition 1:561, 3:309, 3:407 Cardiovascular disease (CVD) 2:105–110 definition 2:105 fat consumption and 2:449–450 mortality due to 2:105 prevention/control Beef in an Optimal Lean Diet (BOLD) study 2:105, 2:106–107 Dietary Approaches to Stop Hypertension (DASH) diet 2:105, 2:106, 2:108T diet effect on risk factors 2:106 eating patterns (USA) 2:108T lean beef, role 2:107 meat composition modification 2:109 meat labeling and 2:107–109 red meat consumption and 2:106 risk factors 2:105–106 diet effect on 2:106 lipid levels 2:105, 2:106 modifiable and nonmodifiable 2:105–106, 2:106T obesity and overweight 2:105, 2:106 see also Obesity therapeutic lifestyle change (TLC) 2:105, 2:106 types and causes 2:105 Cardium edule (cockles) 3:384

478

Index

Care and husbandry practices beef quality assurance (BQA) guidelines 3:174, 3:175T see also Animal welfare Carne de sol 1:518 Carnitine as animal-derived nutraceutical/meatbased bioactive compound 2:34, 2:34F, 2:131–132 deficiency 2:131–132 Carnosic acid, warmed-over flavor prevention 1:413 Carnosine 2:119, 2:447, 3:396 biological activity and role 2:119 definition 2:118, 3:394 functions and properties 2:447 as meat-based bioactive compound 2:34, 2:34F b-Carotene 2:121 yellow fat, beef 3:334 Carotid artery occlusion, exsanguination 1:562 Carp 3:340–341T nutritional content 3:336–342, 3:342T Carrageenan 1:5 Carrying capacity of pastures, factors affecting 2:477, 2:477T Cartilage, contamination with 2:22, 2:22T detection 2:25, 2:26F see also Foreign bodies Cartilaginous fish, definition 3:336 Carwell gene 1:14, 1:15T, 1:25T Casein 1:291–292 calpain analysis in meats 1:215 definition 1:1 use as meat extender 1:4 Caseinates 1:291 Caseinophosphopeptides, definition 2:118 Case pulls, definition 3:13 Case ready, definition 3:1, 3:13 Case-ready meat packaging 3:9 advantages/disadvantages 3:10 see also Controlled atmosphere packaging (CAP); Modified atmosphere packaging (MAP) Casings, sausages see Sausage casings Caspases, meat tenderization role 3:441 Caspian red deer 2:194 Casseroling 1:373 Castrated males, bone growth 2:80 Castrated male swine see Barrows Castration, male meat-producing animals 1:97 Catabolic lipid metabolism 2:47–48 definition 2:43 see also Lipolysis Catabolism anabolism vs. 1:353 definition 1:353, 3:102 postmortem 1:353–355 Catabolite repression, definition 3:388 Catalase 3:399 Catecholamines 2:177 growth effects 2:53–54 synthetic 2:53–54

Catfish, off-flavor, seasonal development 1:259 Cathepsins aging role 1:331 analysis in meats 1:215–216 characteristics 3:439 definition 3:438 effect on water-holding capacity 1:281 meat tenderization role 3:433, 3:438–439 cystatins and 3:439 Cattle beef see Beef cattle behavior during handling and transport see Animal behavior, during handling and transport breeds see Cattle breeds carcass composition see Cattle, carcass composition Code of Cattle Care 3:176–177 crossbreeding 1:20–21 dairy see Dairy cattle dehorning, animal welfare 3:103 distractions that inhibit animal movement (beef plant case study) 3:90 domestication 3:358–359 double muscling see Double-muscled animals; Double muscling as Escherichia coli O157:H7 reservoirs 2:359 feed/feeding effect of diet components on methane production 1:73 general aspects 2:478–479 meat and bone meal (MBM), bovine spongiform encephalopathy outbreak and 2:363 see also Ruminants, feed/feeding geographical distribution/number per geographical area 2:212T, 2:213, 2:213T hides by-products 1:113T nonsalt curing methods 1:116 removal see Cattle slaughter process thickness 1:116 lairage see Lairage/lairaging listeriosis 2:351 methane production 1:72 see also Biomethane production and cleanup organic production systems 2:201 origins of, domestication and 3:358, 3:359 over thirty months (OTM), slaughter/meat consumption, bovine spongiform encephalopathy control measures 2:364 preslaughter handling loading and unloading 3:96 movement from lairage to stunning pen 3:100 transportation 3:96, 3:97–98 ruminal contents 2:471–472 Salmonella monitoring/incidence 2:372 slaughter process see Cattle slaughter process stress

eye white response 3:85 vocalization and 3:85, 3:100 vocalization, stress and 3:85, 3:100 as working animals 2:213–214, 2:214F see also Beef; Ruminants Cattle, carcass composition 1:149F, 1:149T bone 1:164–165, 1:165T, 1:166T breed differences 1:19 muscle, distribution 1:149, 1:152F subcutaneous fat, distribution 1:165F see also Beef carcass(es); Carcass composition Cattle breeds 3:328 connective tissue affected by 1:324 differences in bone density 1:164–165 differences in carcass composition among 1:19 domestication 3:358 European 3:329–330, 3:358–359 humped African cattle 3:358, 3:359 Indian zebu cattle 3:359 mitochondrial DNA 3:358, 3:358–359 New World breeds 3:359 origins 3:358 Western (taurine) 3:358, 3:359 see also individual breeds Cattle production systems 2:212–214 cultural factors 2:211 extensive 2:212, 2:213F intensive systems combined with 2:212, 2:213F pastoralism 2:214 Salmonella control and preventive measures 2:374 threats 2:214 traditional 2:212–213, 2:213F see also Beef production Cattle slaughterhouses Salmonella contamination 2:372 stun box and restrainer design 3:90–91, 3:90F Cattle slaughter process 3:284–289 animal handling 3:284 antemortem inspection 3:284 automation see Slaughter-line operation, automation blood collection 3:285 aseptic 3:285 brisket saw 3:288 bung (anus) bagging, typing and separation 3:288 see also Bung dropping/bunging carcass chilling 3:289 carcass splitting 3:288 cattle receiving 3:284 condemned animals 3:284 dentition check 3:287 evisceration see Evisceration exsanguination (sticking/bleeding) 1:562, 3:285 time to loss of brain function 1:562 final carcass decontamination interventions 3:289 final postmortem inspection 3:288 final trimming 3:288 head removal 3:287

Index

head/tongue inspection 3:288 head washing 3:287–288 hide removal (dehiding) 1:113, 3:285–286 automated 1:47 back skinner 3:286 belly skinning 3:286 first leg skinning 3:286 fore-foot removal 3:286 hock removal 3:286 left leg 3:286 leg hang-off (transfer to trolley) left leg 3:286 right leg 3:286 leg steam vacuuming/blow-off 3:286 midline split 3:286 rump/butt skinning 3:286 side pullers 3:286 up puller 3:286–287 hide washing/dehairing 3:285 hoisting 3:285 hot carcass weight measurement 3:288 hot fat trimming 3:288–289 immobilization 3:418 oxtail removal 3:288 pluck removal/inspection 3:288 preevisceration washing 3:287 retained carcasses 3:288 shackling 3:285 spinal cord removal 3:288 steam vacuuming stations 3:287 stunning (knocking) see Stunning suspect animals 3:284 tongue removal 3:287 tongue washing 3:287–288 viscera removal/inspection 3:288 weasand tie and separation 3:287 see also Beef carcass(es) Causal model definition 2:425 meat quality see Meat quality modeling Cavity fat 1:159–160, 1:165T see also Carcass fat; Fat; Intramuscular fat CCAAT/enhancer-binding protein a (C/EBPa), brown adipose tissue development 2:44 CCAAT/enhancer-binding protein b (C/EBPb) brown adipose tissue development 2:44 white adipose tissue development 2:44–45, 2:45 CCAAT/enhancer-binding protein d (C/EBPd), white adipose tissue development 2:44–45, 2:45 Cecina 1:518–519, 1:551 Cefsulodin–Irgasan–Novobiocin (CIN) agar, Aeromonas isolation 2:321 Celery, as natural nitrate source 1:8, 1:432 Cell(s) embryonic stem see Embryonic stem cells fat see Adipocyte(s) planktonic see Planktonic cells somatic see Somatic cells sublethal injury, hurdle technology 2:345 Cellar phase, dry-cured ham production 2:90 Cell-detaching E. coli 2:358

Cell-to-cell signaling molecules, biofilm formation role 1:67–68 Cellulose 2:474 resistance to degradation 2:474 Cellulose casings see Sausage casings Center-track restrainers, cattle stunning 3:284–285 Central American and Caribbean Symposium on Meat Processing 3:148T Centralized packaging systems 3:9 advantages/disadvantages 3:10 see also Controlled atmosphere packaging (CAP); Modified atmosphere packaging (MAP) Central tendency, measurement 1:187–188 Central testing, genetic selection programs 1:24–25 Centrifugation high-speed, water-holding capacity measurement 2:166 low-speed, water-holding capacity measurement 2:166, 2:166F Centripetal growth 2:57–58 Cephalopods 3:385–386 welfare issues 3:386 Cephaloridine–fucidin–cetrimide agar (CFC), pseudomonads enumeration 2:308, 2:308T Ceramic contamination, meat 2:23, 2:23T Cereal products 1:299 Cereulide 2:327 Certification definition 3:159 quality management systems see Quality management activities/systems Cervids 2:193 bone yield 3:349T fatty acid composition 3:348, 3:350T fat yield 3:349T lean yield 3:349T meat proximate composition 3:351T see also Deer Cervus elaphus see Red deer Cestodes 3:35–38T see also Parasites CH4 see Methane Chain-conveyor systems 3:131–132, 3:132F, 3:133F horizontal serpentines 3:131–132, 3:132F straight-line 3:131–132, 3:132F uses 3:132 vertical serpentines 3:131–132, 3:133F Chalaf knife 1:561 Channel Island cattle breeds, yellow fat 3:334 Charcuterie see French meat products and dishes Charolais cattle 3:329–330, 3:329F Charqui 1:519, 1:519F Check all that apply (CATA) 3:274 definition 3:272 Chelators definition 1:410 as hurdle technology 2:346 oxidation inhibition 1:414

479

Chemical(s), meat production-related environmental impacts 1:506 see also specific chemicals Chemical analysis 1:173 major meat components see Chemical analysis, major meat components micronutrients and other minor meat components see Chemical analysis, micronutrients and other minor meat components odors see Odor(s), chemical analysis physicochemical methods see Chemical analysis methods raw material composition see Raw material composition analysis standard methods see Chemical analysis, standard methods veterinary drug residue see Veterinary drug residue analysis Chemical analysis, final product composition for labeling 1:169 calculations see under Nutritional labeling product sampling 1:169 test procedures 1:169 Association of Analytical Communities recommendations 1:169–170, 1:170T test sample preparation 1:169 see also Chemical analysis, major meat components; Chemical analysis, micronutrients and other minor meat components; Chemical analysis, standard methods; Nutritional labeling; Raw material composition analysis Chemical analysis, major meat components 1:206–211 fat see Fat analysis methods glycogen 1:211 protein see Protein analysis methods see also Raw material composition analysis Chemical analysis, micronutrients and other minor meat components 1:212–216 cholesterol 1:215 enzymes 1:215–216 minerals 1:214–215 vitamins 1:212 fat-soluble see under Fat-soluble vitamins water-soluble see under Water-soluble vitamins see also Raw material composition analysis Chemical analysis, standard methods 1:193–199 chemical standards and official methods on meat and meat products 1:195–198 AOAC International 1:197 ISO (International Standardization Organization) 1:197 NMKL (Nordic Committee on Food Analysis) 1:197 Codex Alimentarius’ guidelines for numeric values for method performance criteria 1:195, 1:196T collaboration 1:198 method development process 1:195

480

Index

Chemical analysis, standard methods (continued) NMKL (Nordic Committee on Food Analysis) 1:195, 1:196F standard developing organizations see Standard developing organizations (SDOs) standardization work (collaborative studies) 1:194 determination of performance characteristics 1:194 analysis of samples 1:194–195 material quality 1:194 number of laboratories 1:194 statistical analysis of results 1:195 testing materials used 1:194 performance characteristics examined 1:194 use of 1:193 Chemical analysis methods 1:173–179 chromatographic methods 1:176 gas chromatography 1:176–177 liquid chromatography 1:177 classical methods 1:174 gravimetric analysis 1:174 volumetric analysis 1:174 electrochemical methods 1:174–175 potentiometric methods 1:174–175 voltametric and polarographic methods 1:175 electronic sensing 1:177 flow injection analysis 1:177 mass spectrometric techniques see Mass spectrometry miscellaneous techniques 1:178 quality assurance 1:178 sample pretreatment 1:173 ashing/mineralization/hydrolysis 1:173 chromatographic separation 1:174 derivatization 1:174 extraction 1:173–174 liquid–liquid 1:174 matrix solid-phase dispersion 1:174 simple 1:173–174 solid-phase 1:174 solid-phase microextraction 1:174 homogenization 1:173 spectrophotometric methods see Spectrophotometry see also Chemical analysis, standard methods Chemical antimicrobials, processed meat decontamination see Processed meat, decontamination Chemical contamination finfish 3:342 see also Chemical hazards, meat-associated; Environmental contaminants Chemical depilatory agents, hide dehairing 1:117–118 Chemical energy, definition 1:508 Chemical hazards, meat-associated 3:64–69 dioxins 3:68 disinfectants 3:67 lead 3:67–68 mycotoxins 3:68

nitrites/nitrates 3:68 polycyclic aromatic hydrocarbons 3:67, 3:324 veterinary drug residues see Veterinary drug residue(s) Chemical hazards, risk assessment 3:228–229 Chemical lean 2:480 definition 2:480 Chemical residues definition 3:216 feed/drug see Residues, feed/drug meat production-associated see Residues, meat production-associated Chemical sanitizers Bacillus cereus control 2:328 see also Cleaning agents; Disinfectants Chemical stunning, farmed fish 3:422–423, 3:424 Chemical tenderizing mechanisms see Tenderizing mechanisms, chemical Chemical treatments, decontamination of fresh meat 2:277–278 Chemometrics definition 3:70 near infrared (NIR) spectroscopy and 3:71–72 Chemotaxonomy, definition 2:348 Chernobyl accident 1:500–501 Chest sticking 1:561–562 Chevon definition 3:374 see also Goat meat ‘Chewing the cud’ (rumination) 2:472, 2:474–475 Chianina cattle 3:329–330, 3:330F mature body size 3:331 Chicken(s) 3:369–370 Clostridium difficile infection 2:341 domestication 3:369 dual-purpose 3:369, 3:369F feet, as edible by-product 1:110 see also Broiler(s); Poultry Chicken meat Arcobacter butzleri contamination 2:340–341 Clostridium difficile contamination 2:341 Clostridium perfringens contamination 2:337–338, 2:340 consumption, trends 3:370 convenience foods 3:370 hot-boned 1:456–457 meat quality problems 3:370 mechanically recovered composition 2:272, 2:273T safety 2:274 uses 2:272 nutrient composition 3:370, 3:371T vacuum packaging unsuitability 3:29 warmed-over flavor 1:413 Chicken meat production systems 2:204–205, 2:463, 3:369–370, 3:370F commercial enterprise, definition 2:204 free-range 2:204, 2:204F, 2:205, 2:205, 2:205F

grower diet, definition 2:204 history 3:369 intensive 2:204, 2:205–206 drinking system 2:208 feeding system 2:207–208, 2:208F heating and cooling 2:207, 2:207F house and bird management 2:209–210 housing 2:204, 2:205–206, 2:205F insulation 2:206 lighting 2:208 litter 2:208–209 stocking density 2:209 ventilation 2:206, 2:206F, 2:207F litter 2:208–209 definition 2:204 organic 2:201–202, 2:205 starter diet, definition 2:204 vitamins, definition 2:204 see also Broiler(s); entries beginning poultry Chicken paws 1:110 Chicken wings, Buffalo/hot wings 1:557 Chicks brooding, definition 2:204 management, chicken meat production systems 2:209, 2:209F Chile, provincial meat research institution 2:257–261T Chili con carne 1:557 Chilled foods air transport 2:237 sales, global 2:239 storage 2:228 temperature maintenance 2:238–239 transport see Transport of meat/meat products unwrapped meat 2:229 unwrapped products, display cabinets 3:189, 3:190F wrapped meat 2:229 see also Wrapped products wrapped products, display cabinets 3:189, 3:189F Chilled mirror dew point meters 3:51 calibration 3:53 Chilling accelerated 2:226–227 after cooking 3:182 air absolute humidity 3:180 air blast 3:206–207 air temperature 2:226 air velocity 2:226 conventional 2:226 cryogenic 3:207 definition 3:178 evaporative air chilling 2:226 glycogen debranching enzyme activity 1:354 immersion 2:226 rates 2:226 meat tenderness, meat fiber type effect 2:446 methods 3:179–181, 3:198 moisture evaporation effects 3:180 rate 3:180 primary 2:237

Index

process 3:178–179 process models chilling heat loads 2:440–441 chilling times 2:437–440, 2:438F rate and temperature 2:226, 2:236–237 rate increases 3:180 relative humidity decrease for 2:226 secondary 3:205–206 as source of microbial contaminants in fresh meat 2:286 surface fat 3:182 surface mass transfer coefficients 3:180 systems see Refrigeration equipment temperature profiles 3:179, 3:179F time for meat 2:226 water spray use 2:226, 3:180 see also Spray chilling see also Carcass chilling; Cold chain; Refrigeration Chimera, definition 1:92 China 1:522–526 antibiotic growth promotant policy 2:175T inedible raw materials 1:126–127 meat products see Traditional Chinese meat products (TCMPs) pork production, problems 2:216 provincial meat research institutions 2:257–261T Chinese cuisine 1:525, 1:525F Chinese restaurant syndrome 1:525 Chlamydia psittaci, viability in meat 1:29 Chlorine-containing sprays, carcass decontamination 2:278 Chlorofluorocarbon (CFC) compounds 3:199 Choice white grease (CWG) 1:130–133, 1:131T uses 1:131 Cholecalciferol 2:126–127, 2:133–134 Choleglobin, meat color effects 3:15 Cholesterol 1:241 consumption by food type (and country) 2:113T content in edible by-products 1:104, 1:108T in meat 1:222, 1:241, 2:114 chemical analysis 1:215 content 2:114 contribution of intramuscular adipose tissue 1:230–231 lean, concentration 1:230 lean beef 2:107, 2:108T mechanically recovered vs. hand-boned meat poultry 2:272 red meat 2:270, 2:273–274 species differences 1:241, 1:241T shellfish vs. finfish, levels 3:380 Cholesterol ester 1:230 Cholesterol-lowering diet, effect on cardiovascular disease 2:106–107 Cholic acid 2:131 Chondrogenesis, definition 2:49 Chondroitin sulfate, as animal-derived nutraceutical 2:132–133

Chopped hams 1:447–448, 1:448T Choppers, bowl see Bowl choppers Chopping, cure application 1:446 Chorionic binucleated cell, definition 2:49 Chorizo 1:551, 1:551F, 3:246 Christie, Atkins, and Munch–Petersen (CAMP) test see CAMP test Christmas tree(s) definition 1:33 semiautomatic loading of cuts on 1:35 Chromatographic methods amino acid analysis 1:210–211 chemical analysis see under Chemical analysis methods meat species determination 2:266, 2:268T sample pretreatment 1:174 Chromatography, definition 2:265 Chrome tanning 1:120 basification 1:120 ‘wet blue’ moist product 1:116 Chromium supplementation, in leaner carcass production in poultry 2:468–469 Chromogenic media 2:325 definition 2:324 Escherichia coli detection 2:360 Chromophores, ’browning agents’ 1:400 see also Maillard browning Chronic wasting disease (CWD) 2:362, 2:365 Chub, definition 3:241, 3:256 Chukotka 2:194 Chunchul 1:520 Chutes 3:284–285 layout principles 3:91–92, 3:91F Chylomicrons 2:47 Ciguatera toxin, definition 2:8 Cimaterol 2:178, 2:178F, 2:180 Cincinnati pen 3:212, 3:212F, 3:213 definition 3:209 Citric acid 3:80–81 meat tenderization 3:433 as secondary antioxidant 1:414 Cladosporium 2:395, 2:399F meat spoilage 2:401 Clams 3:383 common edible species 3:384T quahog 3:384F, 3:384T Clamshell grilling 1:374 Cleaning, of equipment see Equipment cleaning Cleaning agents 1:510, 1:512–513 associated costs 1:508T definition 1:508 heavy-duty alkaline cleaners 1:513 mild alkaline cleaners 1:513 residues from 3:224 selection, considerations 1:512–513 soil solubility characteristics 1:511T strong alkaline cleaners 1:513 see also Equipment cleaning Cleaning agent–soil contact time 1:510 definition 1:508 Cleaning plan, good manufacturing practice 2:94, 2:94F Clean-in-place (CIP) 1:509–510

481

Clean label alternatives, processed meat 2:282 Clenbuterol 2:68, 2:177, 2:178F, 2:180 Clonal family definition 1:88–89 evaluation 1:89 phenotypic differences 1:88–89 Cloned animals for breeding purposes 1:90 definition 1:83 Cloned offspring syndrome 1:88 Cloned sires 1:90 Clonic muscle spasms, definition 3:407 Cloning 1:83–91 animal conservation 1:90–91, 1:90F artificial insemination vs. 1:89–90 food safety 1:89 genetic gain dissemination 1:89–90, 1:90F genetic gain increases 1:89 genomic selection strategies 1:89 long-term consequences 1:88 meat industry applications 1:89 methods 1:83–84, 1:85F placental abnormalities 1:87–88 transgenerational effects 1:88, 1:88F see also individual techniques Clostridium argentinense 2:331 Clostridium baratii 2:331 Clostridium botulinum 2:330–334 characteristics 2:330–331, 2:331F control in meats 2:332 competing microorganisms 2:334 hurdle technology 2:334 pH 2:333 preservatives 2:333–334 redox potential and atmosphere 2:333 refrigeration 2:332–333 thermal processing 1:385, 2:333 water activity 2:333 see also Canning; Curing agents; Hurdle technology incidence in meats 2:332 irradiation effects 2:143 isolation and characterization 2:331 Clostridium butyricum 2:331 Clostridium difficile 2:21, 2:341–342 antimicrobial resistance 2:415 Clostridium difficile infection (CDI) 2:21, 2:341 Clostridium estertheticum 3:391 Clostridium perfringens 2:335–339 characteristics 2:335–336 foodborne disease 2:18–19, 2:311, 2:335 characteristics 2:337 control and preventive measures 2:338–339 epidemiology 2:337–338 incidence 2:19, 2:338 mechanisms of pathogenicity 2:337 outbreaks, characteristics 2:338 type A gastroenteritis 2:335, 2:337 type C necrotic enteritis 2:335, 2:337 isolation and identification 2:336 conventional methods 2:311, 2:315T, 2:336

482

Index

Clostridium perfringens (continued) detection of C. perfringens enterotoxin 2:336 molecular methods 2:336–337 reservoirs 2:337–338 stormy fermentation 2:311 Clostridium perfringens enterotoxin (CPE) 2:335–336 detection 2:336 mechanism of pathogenicity 2:337 Clothes pin down pullers, cattle hide removal 3:287 CLPG see Callipyge gene (CLPG) cm1, definition 3:70 Coagulase-negative staphylococci (CNS), use in meat fermentation 2:1, 2:3 Coarse ground, definition 1:558 Coating, multilayer packaging films 3:22 Coating equipment see Battering/breading equipment Cobalamin see Vitamin B12 (cyanocobalamin) Cocci, definition 2:289 Coccidiosis control in organic broilers 2:202 prevention, ionophore antibiotics 2:174 vaccines 2:175 Coccidiostats see Ionophore antibiotics Cockles 3:384 Cocktail frankfurters 3:243, 3:259 Cod, Atlantic 3:337–339T nutritional content 3:336–342, 3:342T Cod, definition 1:43 Code of Cattle Care 3:176–177 Codex Alimentarius 2:146–147 definition 2:145 guidelines, numeric values for method performance criteria 1:195, 1:196T Codex Alimentarius Commission (CAC) 1:169, 2:95 definition 2:92, 3:295 Coextruding definition 3:26 frozen meat packaging 3:32 Coextrusion 1:567–568 definition 1:564 multilayer films 3:22 principle 1:567, 1:567F sausages 1:568, 3:239 definition 3:256 Cold boning 3:269–270 Cold chain 2:225–230 chilled unwrapped meat 2:240 chilled wrapped meat 2:239–240 domestic handling 2:240 elements 2:236–237 accelerated chilling 2:238 chilled and frozen storage 2:238–239 conventional chilling 2:237–238 freezing 2:238 primary chilling 2:237 secondary chilling 2:238 thawing and tempering 2:238 see also Chilling; Freezing frozen display 2:240 heat removal 2:236

importance 2:236 process 2:236 refrigeration 2:236 retail display 2:239 transport 2:239 see also Transport of meat/meat products Cold extrusion 1:564–565, 1:565F definition 1:564 Cold-induced toughness 1:343 Cold pasteurization see Food irradiation Cold shortening 1:343, 1:360F, 1:362–363, 1:362F, 3:269, 3:377, 3:432 beef 1:343 definition 1:142, 1:252, 3:374, 3:431 effect on meat aging/tenderness 1:333 tenderness, cooked vs. uncooked meat 3:454F, 3:456 electrical stimulation and 1:493 lamb 1:343 meat fiber types and 2:446 meat toughness 1:256 mechanisms 1:363, 2:446 rigor shortening vs. 1:361 see also Rigor mortis Cold smoking 3:321, 3:325 definition 3:321 see also Smoking, traditional Cold storage, mold growth 2:401 Cold toughening 3:269 Coliforms contamination, fresh meat 2:287 as indicator organisms 2:287, 2:303, 2:304 historical perspective 2:301 Collagen 1:239 cooking-related changes 1:258, 1:326 cross-linking 1:150–151, 1:154F, 1:321 definition 1:321 heat (cooking) affecting 1:258, 1:326 meat quality and 1:326–327 crosslinks, meat tenderness and 1:258 definition 1:1, 1:321, 1:329, 1:527 fibers in perimysium 1:322–323, 1:322F instability in heat 1:326 interaction with decorin 1:327 as meat extender 1:5 meat tenderness and 1:257–258, 1:258T, 1:323 see also Collagen content muscle 1:149–150, 1:321 arrangement 1:153F distribution throughout carcass 1:152, 1:154F relevance to meat production 1:150–151 in muscle connective tissue 1:321, 1:322F see also Connective tissue solubility see Collagen solubility structure 1:153F, 1:321 heat-associated changes 1:326 types 1:321 use in comminuted meat products 1:293 Collagen casings, sausages 3:235 manufactured 3:237–238 Collagen content definition 1:321

as intrinsic determinant of meat tenderness 3:453T tenderness measurement and 3:453T, 3:458 muscle types 1:324–325 Collagenous tendons 1:149–150, 1:153F Collagen solubility definition 1:321 as intrinsic determinant of meat tenderness 3:453T tenderness measurement and 3:453T, 3:458 Colloidal systems 2:422 definition 2:422 Color see Meat color Color additives 3:81 see also Colorings/coloring agents Color development dry/semidry sausages 3:252–253 fermented sausages 2:4 Colorectal cancer 2:101, 2:101 diet associations 2:101 incidence 2:101 meat intake and 2:101 Colorimetric assays, nitrate and nitrite 1:203 Colorings/coloring agents 1:300 as meat extenders 1:5 traditional Chinese meat products 1:523 Color space definition 2:164 Lab see Lab color space RGB see RGB color space Combase 2:435 definition 2:430 Combustion method, protein analysis 1:182T, 1:183–184, 1:209 Commensal bacteria antimicrobial resistance 2:414–415 definition 2:412, 2:414–415 human effects of veterinary drug residues on human intestinal microflora 3:65 nitrate reduction 1:438, 1:439F, 1:440F Commercialization, biltong 1:516–517 Commercial presentation, dry-cured ham 2:90–91 Comminuted, definition 2:265 Comminuted meat, definition 1:7 Comminuted meat products 1:283–288 adulteration 2:265 emerging trends 1:287 added nonmeat ingredients 1:287–288 low-fat meat batter 1:287 low-salt meat batter 1:287 processing strategies to build strong emulsions with lower/low-salt formulations 1:287–288 emulsion/batter stability 1:285–286 fat characteristics and processing conditions 1:286 interfacial protein film formation and gelation 1:285–286 particle size and 1:286 stability assessment 1:287 stabilization mechanisms 1:286–287

Index

importance of emulsified comminuted products 1:283–284 meat emulsion matrix 1:284–285 emulsion theory 1:284–285 physical entrapment theory 1:285 meat proteins 1:284 general classification 1:284 myofibrillar protein functionality 1:284 protein extraction 1:284 nonmeat proteins see Nonmeat proteins preparation 1:449–450, 1:449T species identification see Species determination (meat species) see also Extrusion technology; Functional ingredients, meat products; Minced meats; Processed meat(s); Sausage(s) Comminution, fermented sausage processing 2:2 Commission of the European Communities, meat product definition 1:168, 1:168T Common Agricultural Policy (CAP) definition 2:211 influence on animal production 2:211–212 Company requirements, hazard analysis and critical control point 2:95 Competing microorganisms, Clostridium botulinum control in meats 2:334 Component model definition 2:425 meat quality 2:427–428 Composting 2:155 animal by-products 1:126 definition 2:160 processes 2:160, 2:161F Compounded flavors 1:305 Compressing action, mechanical methods of tenderness measurement 3:455T, 3:456F Compression, water-holding capacity measurement 2:166 Compressor, mechanical vapor compression refrigeration 3:198–199, 3:200 Computed tomography (CT) definition 1:316 meat composition measurement 2:487 pig carcass classification 1:317–318, 1:318F spiral see Spiral computed tomography use in selection programs to improve carcass composition 1:23, 1:23F Computer models, meat quality modeling 2:427–428 Concentrated animal feeding operations (CAFOs) 1:482 definition 1:480 Conches 3:385 Concrete as foreign body in meat 2:23, 2:23T as surface in food production environments/equipment 1:509T Concussion stunning 3:413 see also Mechanical stunning Condensable gases, definition 3:315 Condensed smoke definition 3:315 see also Liquid smoke (smoke condensate)

Condenser, mechanical vapor compression refrigeration 3:198–199, 3:200 Conditioning 1:330 definition 1:329, 1:353, 3:267 see also Aging, meat Conduction see Thermal conduction Confidence intervals (CIs) 1:188, 1:188T Confirmatory method definition 1:217 drug residue analysis see under Veterinary drug residue analysis Conformation, definition 1:307 Conjugated linoleic acid (CLA) 1:228–230, 2:132, 2:452 as animal-derived nutraceutical/meatbased bioactive compound 2:34–35, 2:34F, 2:132 anti-tumorigenic properties 2:132 content of meat 2:116 definition 2:471 feeding to pigs 1:229 in leaner carcass production in poultry 2:468 nutritional enhancement of meat 2:109, 2:452 in ruminant products 2:472–473 structure 1:229F, 2:473F Connective tissue 1:321–328 composition 1:321, 1:321–323 see also Collagen cooking-related changes 1:325–327, 1:327 definition 1:321, 1:329, 3:267 formation 1:321 ‘in vivo’ function 1:323 measurement 1:323–324 near infrared spectroscopy 2:491 meat palatability and 1:257–258 meat tenderness and 1:323, 1:324 meat texture due to properties of 1:323, 1:327 cooling-related changes 1:326 measurement method 1:323–324 meat processing reducing impact 1:323 sensory evaluation 1:323–324 mechanically separated vs. hand-boned poultry 2:272 muscle 1:149–152 distribution 1:321–323 layers/structures 1:321–322, 1:323F see also Endomysium; Epimysium; Perimysium matrix 1:150 protein fibers 1:149–150, 1:321 see also Collagen; Elastin structure 1:321–323, 1:322F thermal stability 1:326 muscle content double-muscled animals 1:467T, 1:469 effect on meat tenderness 1:333, 3:453T muscle content/quality, biological factors affecting 1:324 age 1:324, 1:327 animal species 1:324 breed 1:324 muscle type 1:324–325, 1:326–327, 1:327

483

sex 1:324 organization, different muscle types 1:324–325, 1:325F, 1:327 postmortem changes 1:325 endomysium 1:325 perimysium 1:325 see also Collagen Connective tissue proteins 1:238F, 1:239, 1:267, 1:293 degradation by exogenous enzymes 3:441 effects of heating 1:325–327, 1:327 chemical changes 1:405 on meat microstructure 1:406–407, 1:406F functionality 1:267 emulsification 1:272, 1:272F, 1:273 gelation 1:270 see also Muscle proteins, functionality use in comminuted meat products 1:293 see also Collagen; Elastin; Meat protein(s) Consciousness, definition 3:407 Consumer(s) animal welfare importance 3:102–103 demands, foreign body management in meat 2:23 irradiated foods, lack of demand for 2:144 meat purchase considerations, packaging and 3:16 perception, organic product quality 2:202–203 pricing efficiency of meat and 2:251 reaction, meat color 3:14 requirements for meat 2:251 risks, veterinary drug residues and 3:218 sensory assessment of meat 3:273–274, 3:274F signaling to suppliers over choice 2:251 Consumption (meat) 2:119 attitudes on 2:135, 2:136–137 cancer and see Cancer cardiovascular disease and 2:106 definition 2:248 human requirements 2:119 levels (by country) 2:111–112, 2:112T meat prices and see Meat pricing systems reduced reasons for 3:282, 3:282T see also Vegetarianism US meat consumption per capita 2:248, 2:249F US total red meat and poultry 2:250, 2:252F see also individual meats Contact time, cleaning agent–soil see Cleaning agent–soil contact time Contaminant(s) detection total body electromagnetic conductivity 2:485 X-ray-based 2:485 environmental see Environmental contaminants see also specific contaminants

484

Index

Contaminated raw materials identification, use of indicator organisms 2:302–303 see also Foreign bodies; Fresh meat, microbial contamination Contamination microbial fresh meat see Fresh meat, microbial contamination processed meat see Processed meat, microbial contamination Continental cattle 3:329–330 Continuous injectors, brine see Brine injectors Continuous ovens see under Cooking equipment Contractile proteins 1:257 definition 3:431, 3:438, 3:443 water-holding capacity and see under Water-holding capacity see also Actin; Myofibrillar proteins; Myosin Contraction, muscle see Muscle contraction Contracture definition 1:358 see also Cold shortening; Rigor shortening Controlled atmosphere packaging (CAP) 3:9–12 color properties and 3:9–10 definition 3:1, 3:9, 3:9 equipment see Packaging equipment key factors for success in product quality 3:12 purpose of 3:9–10 spoilage in, factors affecting 3:391–392 Convection, thermal 1:139, 3:197 definition 1:385, 2:225, 2:236, 3:131, 3:184, 3:196 forced 3:197 definition 3:131 free, definition 3:131 natural 3:179, 3:197 surface heat transfer 3:197, 3:197F Convection ovens 1:386–387 forced-air 1:387, 3:134–136, 3:134F see also Cooking processes Conveyors, as coating (battering/breading) equipment 3:121 Cooked bratwurst (white hots) 3:260 Cooked ham definition 2:82 French 1:528–529, 1:529F stress-induced pale, soft, and exudative meat 1:342 Cooked ham production 2:82–86 brine preparation and injection 2:83–84 cooking 2:85 cooling 2:85 preparation for marketing 2:85–86 selection and preparation of raw material 2:82–83 stuffing and molding 2:84–85 tenderization 2:84 definition 2:82 tumbling-massaging 2:84 see also Brine curing

Cooked meat(s) bacteriocin application 1:79, 1:79F color, effects of meat packaging atmosphere 3:11 desirable meaty aromas 1:381, 1:382F pigments see Pigments uncooked vs., tenderness measurement 3:454–456, 3:454F volatile compounds see Volatile compounds Cooked meat flavor development 1:258–259 reactions 1:258 see also Flavor(s) Cooked salami 3:243 Cooked sausage(s) 3:241–247 advantages 3:241 cure accelerator 3:242 cured products 3:243 German see German sausages, cooked production 3:241–243, 3:244F casing stuffing 3:243 grinding 3:242, 3:242F mixing 3:242 nitrite addition 3:242 nonmeat ingredients 3:242 salt addition 3:242 sugar/sweetener addition 3:242 water addition 3:242 standards of identity 3:243 types 3:241 uncured products 3:245–246 see also individual products Cooking 1:330, 1:370–376, 1:385, 1:386 antimicrobial resistance considerations 2:415 brine-cured meats 1:422–423 carcinogen formation 2:447 changes in meat during heating 1:370–371, 1:371F muscle fiber types 2:446 coated (battered/breaded) products 3:120–121, 3:121F cooked ham production 2:85 definition 1:329, 3:267 effect on meat proteins 2:112 effect on weight loss 1:371F, 1:376 see also Cooking loss extrusion see Extrusion cooking heating process in meat 1:371, 1:372F heme iron and 2:125 methods see Cooking methods mixing equipment and 3:127 muscle connective tissue changes see Connective tissue as predrying treatment 1:474 processes see Cooking processes resting period after cooking 1:374 sensory aspects of meat quality and 3:270–271 temperature control and timetable 1:374 effect on tenderness 1:326, 1:330, 1:330F, 3:454F, 3:456 time, control 3:136T, 3:139

typical heat transfer coefficients 1:386, 1:387F see also Maillard reaction; Thermal processing Cooking equipment 3:131–133 batch see Batch ovens continuous 3:131 belt conveyors 3:133, 3:133F, 3:134F chain-conveyor systems see Chainconveyor systems walking beam systems 3:132–133, 3:133F heating systems 3:137 see also Thermal processing Cooking loss 1:370, 2:451 definition 1:253, 2:37 difference between cuts of meat 1:376 effect of cooking method 1:376 effects of heating temperature 1:371F, 1:376, 1:407, 1:408F meat pH and 1:408 water-holding capacity measurement 2:167 Cooking methods 1:370 belt grill cooking 1:374 clamshell grilling 1:374 common terms 1:386T consideration before sensory analysis of meat 3:275 effect on cooking loss 1:376 effect on eating quality of meat 1:374 color 1:374 odor and flavor 1:374–375 texture 1:375–376, 1:375F, 1:376F main/common 1:386T boiling/stewing/water bath 1:330, 1:373 braising/casseroling 1:373 broiling 1:373 low-temperature cooking 1:372F, 1:373 microwave cooking 1:301, 1:373 pan broiling/panfrying 1:373 roasting 1:372–373, 1:372F sous vide 1:373–374 Cooking processes 3:133–134 control systems 3:136, 3:136T air temperature measurement 3:136 air velocity and airflow patterns 3:136F, 3:138–139, 3:138F cooking time 3:136T, 3:139 effects of dry-and wet-sensor temperatures on drying and heating rates 3:136–137 heat sources 3:137 moisture control 3:137–138 pinking 3:137 relative humidity measurement 3:136 temperature variation 3:139 cooking processes 3:140 oven design 3:139 product loading 3:139–140 product shape 3:140 forced-air convection ovens 3:134–136, 3:134F smoking processes and 3:134, 3:134–135, 3:136 steam and hot water cookers 3:134 see also Thermal processing

Index

Cooking time, control 3:136T, 3:139 Cook-in packaging 3:23–24 Cook yield, water-holding capacity measurement 2:167 Cooling Bacillus cereus control 2:328 chicken meat production systems 2:207, 2:207F cooked ham production 2:85 mixing equipment 3:127 see also Refrigeration Cooling cells, pork quality 3:169 Copolymers, packaging film chemistry 3:21 Coppa 1:551 Copper, lipid oxidation 1:411 Core temperature consideration before sensory analysis of meat 3:275 definition 3:272 Corn dogs 3:243 Corneal reflex, definition 3:413 Corned beef 1:442 definition 1:442 Middle East meat products 1:553–554 production procedure 1:449 Corn proteins, use in comminuted meat products 1:294 Corn syrup, as sweetener in meat products 1:9, 1:444 Coronary heart disease 2:105 see also Cardiovascular disease (CVD) Cosmetics, animal by-product use 1:129 Costameres, definition 3:431, 3:443 Costa Rica, provincial meat research institution 2:257–261T Costs cryogenic refrigeration 3:182 food irradiation 2:144 hazard mitigation intervention 2:223 surveillance 2:222–223 laboratory accreditation and notification 2:148 mechanical conditioning 3:146 packages 3:20 see also Economics Cottage industry, definition 2:190 Cotto salami 3:243 Cotyledon, definition 2:49 Country-cured hams, molds in 2:401 Country-of-origin labeling (COOL) 1:483 definition 1:480 Country-style sausage 3:264 Coypu 2:196 Crab 3:380 blue 3:382T, 3:383F common edible species 3:382T Crackling 1:114 Cracklings (crax) 1:128 Crawfish 3:380–381 red swamp 3:381 white river 3:381 Crax (cracklings) 1:128 Crayfish 3:380–381 Pacific 3:381 Creatine phosphate (CP)

as ATP buffer 1:355 storage 1:353 Credence attributes 2:232–233 definition 2:231 Creutzfeldt–Jacob disease (CJD) 2:366 iatrogenic 2:366, 2:366F new variant (vCJD) 2:20, 2:362, 2:366, 2:366F sporadic 2:366, 2:366F Critical control point definition 3:295 see also Hazard analysis and critical control point (HACCP) Critically important antibiotics (CIAs), guidance documents 3:66 Crocodiles production systems 2:196–197 slaughter process 3:293 Crohn’s disease, Mycobacterium avium subsp. paratuberculosis (MAP) association 2:342 Crop, removal 3:307 Crossbreeding 1:20–21, 1:21F cattle 3:330–331 inbreeding depression 3:328 Crowd pens animal handling/behavior and 3:87 use of following behavior 3:87 definition 3:84 layout principles 3:91–92 Crumbs, applicators 3:119–120, 3:120F see also Battering/breading equipment Crustaceans 3:380 immobilization 3:419 welfare issues 3:386 see also specific crustaceans Cryogenic cooling 3:187–188, 3:207 Cryogenic freezing 3:182 Cryogenic refrigeration 3:181 costs 3:182 Cryogenic tunnels 3:207 Cryogens 3:181 Cryptococcus laurentii, lamb sensory properties 2:400 Culatello 1:550–551 Cull cattle dressing percentage 3:333 fat thickness 3:332 yellow fat 3:334 see also Cattle Cultural factors, animal production 2:211 Culture media laboratory accreditation requirements 2:149–150 spoilage bacteria enumeration see Spoilage bacteria types 2:306 see also individual types Culture system, natural curing 1:431 Cup anemometer 3:54, 3:55F Cure accelerator(s) 1:298 compounds used as 1:298 cooked sausages 3:242 emulsification processes 3:257 Cured fish 3:342 Cured flavor

485

Wiltshire bacon 1:62 see also Cured meats, flavor Cured meats analysis of nitrite and nitrate 1:203 color 1:416, 1:442 chemistry 1:417, 1:418F, 1:419F dry-cured meats 1:427 conventional ingredients 1:430 see also Curing, ingredients dry-cured see Dry-cured products flavor chemistry 1:417 development, nitrite-cured meats 1:381–383, 1:383F dry-cured products 1:428, 1:428T historical aspects 1:283–284 human disease/cancer association 1:436 natural see Naturally cured meat products nitrite reduction 1:423–424 organic see Organic cured meat products pigments 1:250, 1:250T product formulation 1:444–445 production procedures 1:442–452 natural nitrate- and nitrite-free cured meats 1:450–451, 1:451T specific products 1:446–447 bacon 1:446–447 comminuted meat products 1:449–450, 1:449T corned beef 1:449 Frankfurters, and cured sausages 1:449–450, 1:449T hams see Ham(s) see also Curing tenderness, mechanical conditioning and 3:145 traditional Chinese meat products 1:524T, 1:525 see also Nitrate; Nitrite Curing 1:416, 1:442–452 agents see Curing agents application of cures 1:445–446 brine see Brine curing chemistry 1:417 cured meat color 1:417, 1:418F, 1:419F cured meat flavor 1:417 conventional 1:430 ingredients 1:430 see also ingredients (below) definition 1:200, 1:436, 1:558, 3:64 dry see Dry curing hides see Hide(s) historical perspectives 1:442 ingredients 1:416, 1:417–418, 1:430, 1:443 cure 1:443–444 see also Curing agents dry-cured ham production 2:89 erythorbate 1:419–420, 1:444 meat 1:443 polyphosphates 1:420, 1:444 salt 1:418, 1:443 seasonings and flavors 1:420, 1:444 sweetener 1:420, 1:444 water/ice 1:443

486

Index

Curing (continued) natural see Natural curing vacuum packaging and 3:29 see also Cured meats Curing agents 1:200–205, 1:443–444 analysis 1:203 chemistry 1:201, 1:250 concentrations in meat products 1:202–203, 1:202F effect on muscle enzyme activity 1:427 ingoing and residual amounts definition 1:200 legal requirements 1:200, 1:201T, 1:430, 1:431T, 1:443 nitrosamine formation see Nitrosamines reasons for addition 1:200–201 regulations 1:200, 1:201T, 1:430, 1:431T, 1:443 toxicological aspects 1:8, 1:205, 1:205T, 1:437–438 see also Curing; Nitrate; Nitric oxide (NO); Nitrite Curing pickle definition 3:123 see also Pickle curing Current, definition 1:486 Current Good Manufacturing Practices definition 3:168 pig feeding 3:170 Curved races 3:91, 3:91F Customer demands foreign body management in meat 2:23 see also Consumer(s) Cutability cattle 3:333 definition 3:328, 3:333, 3:363 Cutability estimate 3:333 Cut methods, meat tenderization see Tenderizing mechanisms, mechanical Cuts, wholesale/primal/subprimal, definition 3:13 Cutting and boning 1:142–147 cold boning 3:269–270 effects of cutting on meat color 3:14 future trends 1:463 hot boning see Hot boning market specifications 2:234 packaging developments and 1:463 prerigor (hot processing/hot boning) 1:458 semihot boning 1:142–144, 1:144T as source of microbial contaminants in fresh meat 2:286 terminology 1:458, 1:458 traditional 1:142, 1:458–464 see also individual meats/carcass types Cutting and boning, automation 1:33–42 beef carcass cutting and boning 1:36–37 automatic loin boning 1:37 cutting and trimming 1:37, 1:38F primal cutting and quartering 1:36–37 yield management and traceability 1:37–38 opportunities and challenges 1:34 ovine cutting and boning 1:38–39

carcass breakdown 1:38, 1:39F drivers for automation 1:38–39 mechanized task replacement 1:39–40, 1:40F robotic automation 1:40–42, 1:41F pork cutting and boning 1:34 automatic cutting of pork middles 1:34–35, 1:35F, 1:36F automatic primal cutting 1:34 automatic sorting and buffering 1:35 automation of boning processes 1:35 concept design 1:34, 1:35F industrial robot solutions 1:36, 1:37F semiautomatic loading of cuts on ’Christmas trees’ 1:35 skinning/derinding 1:35–36, 1:36F see also Slaughter-line operation, automation Cutting equipment 3:126–130 dicers 3:130 slicers 3:130 vertical cutters 3:129–130 see also Particle reduction equipment Cutting plants, Salmonella contamination 2:372–373 Cuttlefish 3:386 Cyanocobalamin see Vitamin B12 (cyanocobalamin) Cyanometmyoglobin 1:246, 1:247T Cyclopentapyrazines, formation via Maillard reaction 1:396, 1:396F Cyprus, sheep and goat production 2:215 Cystatins 3:439 Cysticercosis, definition 2:211 Cytochrome c, in fresh meat 1:247T, 1:248 Cytoplast 1:84–87 Cytoskeletal proteins 1:358 definition 1:329, 1:358, 1:486, 3:431, 3:438, 3:443 Cytotoxicity, definition 2:405 Cytotoxic necrotizing E. coli 2:358 Cytotoxin, definition 2:317, 2:340 Czech Republic, meat research institution 2:257–261T

D Dairy cattle 3:330 bulls 3:330, 3:330F marbling 3:333–334 organic systems 2:201 propensity to fatten 3:332 Staphylococcus aureus infections, protection against, genetic engineering 1:94–95 Dak galbi (Korean dish) 1:546F, 1:548 Danish bacon, production codes of practice 1:58 Danish Method, added water calculation 1:170–171 Danish Regulation for Bacon Production 1:58 Dark, firm, and dry (DFD) meat 1:343 beef see Dark-cutting beef (DCB) causes 1:339F, 1:340, 1:343, 1:356, 1:356F

definition 1:339, 2:489 double muscled animals 1:344 high pH 1:343 in-carcass distribution 1:343 pH measurements 2:492 see also pH, measurement, meat pork 1:343, 3:365–366 lairage period and 1:367, 1:367T preslaughter stress and 1:366, 3:268–269 preslaughter stress and 3:100–101 water-holding capacity 2:164–165 Dark-cutting beef (DCB) 1:263, 1:263F, 1:343 causes 1:356 double muscled animals 1:344 in-carcass distribution 1:343 see also Dark, firm, and dry (DFD) meat Dark field radiology definition 2:22 foreign body detection 2:30F, 2:31 Databases nutritional labeling 1:169 online, quantitative trait loci (QTL) 1:13 predictive microbiology 2:435 Dawood Basha 1:554 definition 1:553 Death (human), causes 2:105 Decapods welfare issues 3:386 see also Crustaceans Decarboxylases 1:427 definition 1:425, 3:248 flavor development role in dry sausages 3:252, 3:253T Decision limit (CCa) definition 1:217 veterinary drug residue analysis 1:220 Decision-making, applied ethics and 3:280–281 Decontamination fresh meat see Fresh meat, decontamination processed meat see Processed meat, decontamination thermal surface processes see Thermal surface decontamination processes Decorin, collagen interaction 1:327 Deep butt, beef sides 3:179 Deep fat frying 1:388 Deep-fried meat-based dishes, Japanese 1:544, 1:544F Deep leg, lamb carcasses 3:179 Deep shoulder, lamb carcasses 3:179 Deer 3:347–348 behavior during handling and transport see Animal behavior, during handling and transport bovine spongiform encephalopathy and 2:364 carcass yields 3:348 chronic wasting disease 2:362, 2:365 fatty acid composition 3:348, 3:350T hide by-products 1:113T lean yield 3:348, 3:349T production systems 2:193–194

Index

red see Red deer slaughter process 3:290–291 species farmed 3:347–348 see also Venison Deforestation, livestock production-related 1:503 Dehairing 1:117–119 cattle hides 3:285 machine 1:114, 1:117–118 pig carcasses 1:368–369 Dehiding (mechanical pulling) 1:115 beef carcasses see Cattle slaughter process pig carcasses 1:114, 1:368–369, 3:298 Delivery vans, meat/meat products see Transport of meat/meat products Delta-T cooking cooked ham production 2:85 definition 2:82 Demand, definition 2:248 Demand curve, meat pricing 2:248 Demand index Choice beef, in USA 2:248–250, 2:250F pork, in USA 2:250, 2:251F Denaturation, proteins see Protein denaturation Denatured globin hemochrome 1:248–249, 1:249T Denmark antibiotic growth promotants managing without, results 2:176 policy 2:173–174 antibiotic resistance monitoring program 2:175 meat research institutions national 2:255–256T provincial 2:257–261T specific pathogen free pig production 2:187–188 de novo, definition 2:75 de novo lipogenesis (DNL) 2:45–47, 2:46F Density 3:460–461 definition 3:460, 3:460 meat products below freezing temperature 3:461 composition effects 3:461, 3:461T ice fraction 3:461 temperature variations 3:461 volume measurement issues 3:460 Denver Style ribs, cutting 1:463 Deoxymyoglobin 3:397, 3:397F change to 3:27–28 definition 3:9, 3:26 isosbestic point 3:72–73, 3:74F meat color and 2:167–168 in packaged fresh meats 1:246–248, 1:246F, 1:247T vacuum-packaged meat 3:27, 3:28, 3:32 see also Myoglobin Deoxyribonucleic acid (DNA) see entries beginning DNA Derinder, pork 1:35–36, 1:36F Derivatization 1:174 Dermal skin fibroblasts, nuclear transfer 1:84 Derzsy’s disease, imported meat commodities 1:29

Detection capability (CCb) definition 1:217 veterinary drug residue analysis 1:220 Detection limit, foreign bodies in meat see Foreign bodies Deterministic model, definition 2:430 Deuteromycetes (Fungi imperfecti) 2:395 Developing countries, leather production 1:112 Devices, patenting see Patents, examples of Dewcon humidity meter 3:51–52 Dew point 3:50, 3:50F definition 3:50 Dew-point generator, hygrometer calibration 3:53 Dexamethasone adipocyte differentiation 2:45 inflammation treatment 2:53 Dexter cattle, mature body size 3:331 Dextrose 1:297 cured meat products 1:298 Dextrose equivalents 1:297 al-Dhabh definition 3:209 see also Halal slaughter Diacetyl, definition 1:76 Diarrhea, due to Aeromonas 2:319 Diarrheal syndrome, Bacillus cereus 2:326, 2:326–327, 2:327 Dicers 3:130 Dicrocoelium 3:34–39, 3:35–38T, 3:40 Die, definition 1:564 Dielectric constant, definition 1:180 Dielectric heating 1:388–389 definition 3:202 thawing methods 3:207 see also Microwave(s) Dielectric moisture sensor 3:53, 3:53F Die plate, definition 3:241 Diet(s), human 2:118–123 cancer and 2:101 see also Cancer guidelines 1:483 lean beef, role 2:107 meat as important component 2:118 weight-reducing 2:109 see also Nutrition (human) Dietary amino acids, in pig feeds 2:458–459, 2:459T Dietary antioxidants warmed-over flavor prevention 1:413–414 see also Antioxidant(s) Dietary Approaches to Stop Hypertension (DASH) 2:105, 2:106 diet 2:108T Dietary effects, meat flavor 1:380 Dietary energy, in pig foods 2:458 Dietary fibre, nutritional enhancement of meat products 2:452–453, 2:453T Dietary guidelines, humans 1:483 Diet components/ingredients pig feed 2:459, 2:460T reduction of methane production in ruminants 1:73 see also Feed(s)

487

Difference gel electrophoresis (DIGE), as proteomics tool 3:155 Differential media 2:306 Escherichia coli O157:H7 2:360 Differentiating infected from vaccinated animals (DIVA) vaccines, pigs 2:187 Diffusely adherent E. coli 2:358 Diffuse reflection definition 2:164 theory of meat color measurement 2:168 Digesters, anaerobic 1:73, 1:74F, 2:154–155 Digestible energy (DE) in pig foods 2:458 requirement, growing pigs 2:459, 2:461T Digestion, in ruminants see Ruminants Digestion rate, of proteins 2:118 Digestive tract, poultry 2:463 Dihydrotestosterone, pubertal growth 2:53 Dioxins 1:498, 3:68 concentrations in meat and fish 1:499 legislation 1:498–499 tolerable intake 1:498 Direct-fired gas burners 3:137 Direct genetic markers 1:13, 1:14F Direct plating, meatborne pathogens 2:310 Disease prevention foodborne illness see Foodborne pathogens, control measures organic livestock production, regulations 2:199 see also specific diseases Disinfectants associated health risks 3:67 residues from 3:224 Dismountable joint design, processing equipment 1:511, 1:512F Disodium guanylate 1:300 Disodium inosinate 1:300 Distiller’s grains with solubles (DGS) 3:428 definition 3:427 dried, pork quality and 3:170 Diterpenes, warmed-over flavor prevention 1:413 DIVA (differentiating infected from vaccinated animals) vaccines, pigs 2:187 DNA, mitochondrial see Mitochondrial DNA DNA-based genotyping, bull assessment 3:331 DNA-based methods 2:294–300 detection of foodborne pathogens see Foodborne pathogens, molecular detection species determination (meat species) 2:265, 2:266–267, 2:268T PCR-based methods see Polymerase chain reaction-based methods, meat species determination subtyping of foodborne pathogens see Foodborne pathogens, DNA subtyping DNA markers 1:12–18 direct 1:13, 1:14F indirect 1:13, 1:14F quantitative trait loci (QTL) and 1:13

488

Index

DNA markers (continued) role in genetic improvement of carcass and meat quality traits 1:12–13 types 1:13 see also Genomic technology/modern genetics, application in meat industry; Marker-assisted selection (MAS); Quantitative trait loci (QTL) Docosahexaenoic acid (DHA) 2:133, 3:394–395 sources 2:133 Documentation good manufacturing practice 2:93–94, 2:93F quality management systems 3:165 Dodecadepsipeptide definition 2:324 emetic toxin 2:327 Doe, definition 2:190 Dog meat 2:197 ‘Dolly’ the sheep 1:84 Domestic animals as Clostridium perfringens reservoirs 2:338 see also individual animal types Domestication of animals 3:357–362 behavioral traits for 3:357–358 cattle 3:358–359 changes in species 3:360 behavioral changes 3:360 genetic footprints 3:361 growth rate increases 3:361 meat composition 3:361 morphological/anatomical changes 3:360–361 PUFAs in meat 3:361 definition 3:357 future prospects 3:361 goats 3:359, 3:374 nature of 3:357–358 origins 3:357 pigs 3:359–360 plant food for 3:357 poultry 3:360 precocial species 3:357 requirements for 3:357 sheep 3:359, 3:374 suitability of wild animals for 3:357 wild ancestors 3:358, 3:358T Domestic handling, of chilled/frozen meat 2:229 Domestic storage, refrigeration equipment 3:189–190 Donkeys, as intermediate hosts for parasites 3:40 Double chamber systems, vacuum packaging 3:30 Double-muscled animals 1:465–470 carcass and meat quality 1:467T, 1:468–469 definition 1:465 genetic background 1:465–467 see also Myostatin gene (GDF8) physiology and metabolism 1:467, 1:467T reproduction, growth, and management 1:467–468, 1:467T

Double muscling 1:343–344, 1:465–466, 2:57, 2:58F, 2:60, 2:72 cattle 2:50–51, 3:330 genetics 2:76 muscle-to-bone ratio 3:331 shear force when cooking 1:344 temperament 3:331 deficiencies 1:344 definition 2:56 dressing yield 1:344 meat tenderness 1:344 stress susceptibility 1:344 see also Callipyge/callipyge condition; Muscle hypertrophy Down puller, cattle hide removal 3:287 dpH/dt 1:487 changes upon electrical stimulation 1:492 definition 1:486 influence on effectiveness of electrical stimulation 1:492 Drains, stockyard 3:93 Dressing (carcass) definition 1:366, 3:290 as source of microbial contaminants in fresh meat 2:286 see also Inverted dressing Dressing percentage cattle 3:332–333 grass vs. grain-finished 3:332–333 typical steer 3:333 definition 2:190, 3:328, 3:332, 3:345 double-muscled animals 1:468 pigs see Pig(s) Dress out see Dressing percentage Dried distiller’s grains with solubles (DDGS), pork quality 3:170 Dried meats/products Brazil and South America see under Brazil and South America definition 1:518 quality 1:478–479 traditional Chinese meat products 1:524T see also Drying; individual products Dried skim milk, calcium-reduced 1:299 Drinking systems chicken meat production systems 2:208 see also Water requirements Drip 1:334 definition 1:329, 1:486, 3:202 see also Water-holding capacity Drip loss 3:204 factors affecting 1:363–364, 1:364F, 3:204 thawing conditions 3:204 measurement 2:165, 2:165F pork 1:339–340 see also Water-holding capacity Driving aids 3:87 definition 3:84 Drug residues see Veterinary drug residue(s) Dry aging 1:337, 2:228, 3:270 see also Aging, meat Dry bulb thermometers 3:51 oven temperature measurement 3:136 Dry-cured ham(s) 1:425, 1:448–449, 1:449T commercial presentation 2:90–91

French 1:529 German 1:531–532, 1:531T Ammerla¨nder Knochenschinken see Ammerla¨nder Knochenschinken Schwartzwa¨lder Schinken see Schwartzwa¨lder Schinken (Black Forest ham) Westfa¨lischer Knochenschinken see Westfa¨lischer Knochenschinken Mediterranean 1:550, 1:550F, 1:551F see also specific types e.g. Iberian ham Dry-cured ham production 2:87–91 classification methods 2:88 development of new quick-maturation products 2:90 raw material 2:87–88 effect of quality 2:87–88 refrigerated vs. frozen 2:88 shape of hams and types of cut 2:88 salting 2:88–89 drying-maturation and cellar phase 2:90 ingredients and additives 2:89 massaging 2:88–89 methodology 2:89 resting period 2:90 smoking 2:89–90 washing 2:89 see also Dry curing; Functional ingredients, meat products; Mediterranean Dry-cured meats, proteomic studies 3:157 Dry-cured products 1:425 sensory characteristics 1:427 color 1:427 flavor 1:428, 1:428T texture 1:427–428 see also Cured meats; Dry-cured ham(s) Dry curing 1:425–429, 1:445 belly bacon 1:56 definition 1:527, 1:550 enzymatic reactions 1:425 curing factors affecting muscle enzyme activity 1:427 lipolysis 1:426–427, 1:426F action of lipases during dry curing 1:427 nucleotides degradation during dry curing 1:427 proteolysis 1:425–426 action of proteases during dry curing 1:425–426, 1:426F microbial evolution 1:427 processing control 1:428–429 salt reduction 1:429 stages 1:425 Wiltshire bacon 1:58 see also Biltong; Curing; Dry-cured ham production; Dry-cured products Dryers belt 1:475, 1:475F cabinet 1:474–475, 1:474F freeze 1:475–476, 1:476F solutions/suspensions, spray dryer 1:478, 1:478F vacuum 1:475, 1:476F Dry heating 1:330 see also Cooking

Index

Drying 1:471, 3:78–79 aim of 1:471 brine-cured meats 1:422–423 definition 1:471, 1:550 equipment for meat/meat products see Dryers physical and chemical changes in food caused by 1:478–479 solid foods 1:472–475 effect of air temperature 1:474 effect of air velocity 1:474 effect of humidity 1:474 effect of size and shape of solid 1:474 predrying treatments 1:474 processes involved/mechanisms 1:473, 1:473F rate of drying curve 1:473, 1:474F solutions and suspensions 1:478 spray dryer 1:478, 1:478F traditional meat-drying facilities 1:476–478 drying room 1:477, 1:477F quick-dry slice vs. traditional process 1:477–478, 1:477F Drying-maturation phase, dry-cured ham production 2:90 Drying room 1:477, 1:477F Dry rendering 1:128 Dry salted meats, Indian subcontinent 1:541–542 definition 1:538 Dry sausage products French 1:528, 1:551 molds in 2:401 Dry/semidry sausages 3:248–255 color development 3:252–253 definitions 3:248 flavor development 3:250–252, 3:253T history 3:248 processing changes 3:250, 3:251F, 3:252F safety 3:253–254 technology 3:248–250 process flow 3:249F texture development 3:253 see also Drying; Fermented sausages Dry-sensor temperature cooking processes effect on drying/heating rates 3:136–137 measurement 3:136 definition 3:131 Dual-energy X-ray (DXA) systems foreign body detection 2:29F, 2:31 meat composition measurement 2:483F, 2:485–487, 2:486F, 2:487F meat quality measurement 2:494 Dual purpose cattle 3:330 Duck(s) 3:372 feet, as edible by-product 1:110 meat consumption, trends 3:372 nutrient composition 3:371T, 3:372 production, historical aspects 3:372 slaughter process 3:293 Dumpling see Momo/dumpling Dunmore sensors 3:51

D-values 1:140 definition 2:143 Dyspnea causes 3:403 definition 3:401

E E. coli see Escherichia coli Eating habits, as driver of meatborne parasite transmission to humans 3:41 Eating patterns, in USA 2:108T Eating quality definition 3:334 effect of cooking methods see Cooking methods effect of freezing 3:193–194 effect of thawing 3:205 see also Meat quality Echinococcus 3:35–38T intermediate hosts 3:35–38T ruminants 3:39 Economics extrusion technology 1:569 of hazard mitigation see Meatborne hazards, mitigation meat pricing see Meat pricing systems nonmeat proteins in comminuted meat products 1:289 see also Costs Edibility 1:126 Edible by-products 1:104–111 cholesterol content 1:104, 1:108T nutritional value 1:104, 1:106T, 1:107T products 1:104–105 blood 1:110–111 brains 1:108–109 chicken or duck feet, and chicken paws 1:110 haggis 1:110 heart 1:105–107 intestines see Intestines jellied 1:110 kidney 1:107–108 liver 1:104–105 meat extract 1:109 oxtail 1:109 pigs’ feet (’trotters’) 1:109–110 pig tail 1:109 pork jowl 1:109 pork skins 1:110 poultry giblets 1:111 spleen 1:111 stock 1:109 sweetbreads 1:108 testicles 1:110 tongue 1:107 trimmings 1:109 tripe 1:108 yield 1:104, 1:105T see also Mechanically separated meat (MSM) Edible films, warmed-over flavor prevention 1:414

489

Effective water diffusion coefficient definition 1:471 water content and 1:473 Egg production global 1:502F organic 2:202 Egg proteins 1:292–293 Eichsfelder Feldgieker, definition 1:530 Eicosapentaenoic acid (EPA) 3:394–395 sources 2:133 Eimeria stiedae 3:35–38T, 3:40 Elastin 1:149–150, 1:239 cooking-related changes 1:325–326 distribution throughout carcass 1:152 in muscle connective tissue 1:321 Elective media 2:306 Electrical immobilization (EI) 3:420 Electrical impedance definition 2:489 meat quality measurement 2:493 Electrical measurements, meat quality see Online measurement, meat quality Electrical sensors, fish freshness assessment 2:13 Electrical stimulation (ES) 1:454, 1:486–496, 3:269, 3:445–446 beef processing 1:145 definition 1:142, 1:274, 1:329, 1:486, 1:486, 3:290, 3:309, 3:431, 3:443 description 1:487 effects 1:486, 1:490–491 color changes 1:490 meat aging 1:335, 1:336F rigor mortis 1:362, 1:362F scientific basis see scientific basis (below) unclear interpretations 1:494, 1:495 water-holding capacity 1:278 see also Tenderness events during ES 1:487, 1:488F pH fall 1:487, 1:488F factors influencing effectiveness of 1:491–492 changes in rate of pH fall (dpH/dt) upon stimulation 1:492 effects of muscle type on stimulation response 1:492 fall in pH upon stimulation 1:492 frequency, voltage/current, pulse shape, and polarity effects 1:492, 1:492F history 1:487 hot boning and 1:492–493 injection of metal ions and 3:432–433 parameters 1:487, 1:489–490, 1:490 pork processing 1:146–147 poultry processing 3:306 pulse waveforms definition 1:486 descriptions 1:489–490, 1:491F effectiveness of stimulation and 1:492, 1:492F safety 1:490 scientific basis for tenderization 1:493 effect on calpain enzyme activity 1:494–495 impact of physical disruption on ions 1:493–494

490

Index

Electrical stimulation (ES) (continued) rigor mortis, cold shortening, rigor contracture calcium levels, and optimum tenderization 1:493 start of tenderization 1:493 structural effects 1:493 see also effects (above) sheep/goat processing 3:313, 3:313F, 3:314F systems 1:487–489, 1:488F, 1:489F Electrical stunning 3:407–412 brain stimulation 3:408 anesthesia 3:408 stunning 3:408–409, 3:408T, 3:409F definition 3:309, 3:421 ethics 3:409 farmed fish 3:422, 3:423F gas stunning vs. 3:401 history 3:407–408 meat quality and 3:409–410 hemorrhaging in muscles 3:410, 3:410F pigs 1:368, 3:298 practical application 3:410–411 fish 3:411, 3:422, 3:423F ostriches 3:411 pigs 3:411, 3:411F poultry 3:411 see also Stunning, poultry rabbits 3:293, 3:411 ruminants 3:410–411 process 3:407 recommended minimal current 3:408T see also Stunning Electric heating elements, ovens 3:137 Electric prods (goads) definition 3:84 use of 3:87, 3:100 Electroanesthesia definition 3:407 see also Electrical stunning Electrocardiogram definition 3:421 farmed fish, effects of stunning 3:422, 3:423, 3:424 Electrochemical analysis methods see under Chemical analysis methods Electrocorticogram (ECoG), exsanguination 1:562 Electroencephalogram (EEG) definition 3:407, 3:421 farmed fish, effects of stunning 3:422, 3:423, 3:424 neck cutting, pain during 1:562 Electromagnetic contrast, foreign body detection see under Foreign bodies Electromotive force (Emf), definition 3:57 Electronarcosis, definition 3:407 Electronic noses 2:496 definition 2:489 Electronic sensing methods 1:177 Electrophoresis definition 2:265 paper see Paper electrophoresis Electrophoretic techniques, meat species determination 2:266, 2:268T

ELISA see Enzyme-linked immunosorbent assay (ELISA) Elk 2:194 chronic wasting disease 2:362, 2:365 hide by-products 1:113T Embryo bisection 1:84, 1:85F Embryo complementation, embryonic stem cells and 1:84, 1:85F Embryonic cloning 1:84 efficiency 1:87 Embryonic growth cellular systems 2:49–50 endocrinology 2:49–50 gene imprinting 2:49–50 organs 2:50 tissues 2:50 Embryonic stem cells 1:84, 1:92 definition 1:83, 1:92 embryo complementation and 1:84, 1:85F transgenic animal production 1:92 Embryo splitting 1:84 Emerging economies, immobilization and restraint 3:419 Emerging pathogens 2:20–21, 2:340–344 Arcobacter butzleri 2:340–341 Clostridium difficile 2:21, 2:341–342 definition 2:340 Enterococcus 2:20–21 Mycobacterium avium subsp. paratuberculosis (MAP) 2:342 Streptococcus suis 2:342–343 Emetic syndrome 2:324, 2:326 definition 2:324 Emu 3:346T, 3:372 meat 3:346, 3:346T production systems 2:191 trends 3:372 slaughter process 3:292–293 Emulsification 1:271–272, 1:284 characteristics of meat emulsification 1:272, 1:272F definition 1:267 mechanisms 1:272–273 nonmeat proteins and 1:290 proteins involved in emulsion formation/ stabilization 1:273 nonmeat proteins 1:290 see also Comminuted meat products; Meat emulsion(s) Emulsified comminuted products importance of 1:283–284 see also Comminuted meat products Emulsified sausages 3:256–260 casing stuffing 3:258 comminution methods 3:256–257 chopping 3:256–257, 3:257F, 3:258F emulsifying process 3:257 mixing–emulsifying process 3:257, 3:257F, 3:258F cooking 3:258 emulsification processes 3:257–258 emulsion failure (fatting out) 3:259 extracted protein (protein exudate) 3:256 fat preemulsions 3:258–259

German 1:531T, 1:534 Frankfurter Wu¨rschten see Frankfurter Wu¨rschten Halbersta¨dter Wu¨rschten see Halbersta¨dter Wu¨rschten Mu¨ncher WeiXwurst see Mu¨ncher WeiXwurst Pfa¨lzer Saumagen see Pfa¨lzer Saumagen ice addition 3:256 manufacture 3:256 preblending 3:256 types 3:259 Emulsifiers 1:283, 1:299–300 definition 1:283 Emulsifying agents 3:257 Emulsion definition 1:137, 1:283, 1:283 examples 1:283 meat see Meat emulsion(s) Emulsion mills 3:130 Emulsion theory 1:284–285 Emulsion-type sausages see Emulsified sausages Encephalitis, in animal listeriosis 2:351 Endemic diseases, animal welfare 3:104 Enderby Island cattle breed, cloning 1:90F Endocarditis, definition 2:340 Endocrinology 2:49–55 adipogenesis 2:51 embryonic growth 2:49–50 fetal growth 2:49–50 growth 2:49–55 future developments 2:54 recently identified factors 2:54 muscle development 2:74 postnatal growth 2:52 pubertal growth 2:53 see also individual hormones Endometrium cancer 2:102–103 Endomysium definition 1:252 postmortem changes 1:325 structure 1:323, 1:323F Endonucleases, definition 2:294 Endotoxin, definition 2:317 End-over-end tumbler 3:144 Endpoint semiquantitative polymerase chain reaction 2:295–296 Energy dietary, in pig foods 2:458 intake, by food type (and country) 2:113T intake restriction, poultry 2:468 values, calculation 1:171, 1:171T Energy factors 1:171, 1:171T Energy requirements pigs 2:459–461, 2:461T poultry 2:463–465, 2:464T Energy usage, processing plants, reduction 3:428 Enhancement see Meat enhancement Enteric pathogens, definition 2:285 Enteric viruses 2:389 see also Virus(es), foodborne Enteritis Campylobacter 2:384 see also Campylobacteriosis

Index

Clostridium perfringens type C necrotic 2:335, 2:337 see also Clostridium perfringens see also Gastroenteritis Enteroaggregative Escherichia coli (EAEC) 2:357–358, 2:357T Enterobacter, vacuum packaging and 3:31 Enterobacteriaceae curli 1:67 definition 2:285 enumeration media 2:309 indicator bacteria 2:308 psychrotrophic species 2:309 as indicator organisms 2:303–304, 2:304 total counts 2:308, 2:308T, 2:309 Enterococcus antimicrobial resistance 2:415 as emerging foodborne pathogen 2:20–21 Enterohemorrhagic Escherichia coli (EHEC) 2:357T, 2:358 Enterohepatic circulation, definition 1:97 Enteroinvasive Escherichia coli 2:357, 2:357T Enteropathogenic Escherichia coli (EPEC) 2:357T, 2:358 Enterotoxigenic Escherichia coli (ETEC) 2:357, 2:357T colonization factors 2:357 toxins 2:357 Enterotoxins Bacillus cereus see Bacillus cereus Clostridium perfringens see Clostridium perfringens enterotoxin (CPE) definition 1:515, 2:317, 2:335, 2:340 staphylococcal 2:377–378 Enthalpy 3:462–463 definition 3:460, 3:462 volumetric terms 3:463 zero points 3:462 Enumeration, definition 2:306 Environmental contaminants 1:497–501 dioxins see Dioxins PCBs see Polychlorinated biphenyls pesticides see Pesticides radionuclides 1:500 artificial radioisotopes 1:500 incidents resulting in contamination of food with radionuclides 1:500–501 Chernobyl 1:500–501 Fukushima 1:501 natural radioisotopes 1:500 trace elements 1:499–500 Environmental exposure, to antimicrobialresistant organisms 2:417–419 Environmental impact, meat production 1:502–507 biodiversity 1:503 chemicals 1:506 greenhouse gas emissions and global warming 1:504, 1:505F carbon dioxide 1:505, 1:505F indicators of changing climate 1:505–506 methane 1:504–505, 1:505F see also Biomethane production and cleanup

nitrous oxide 1:505, 1:505F see also Greenhouse gases impacts related to nutrient use 1:503 eutrophication and acidification 1:504 nitrogen 1:503–504 phosphorus 1:504 Environmental stewardship and regulation 1:481–482 Enzymatic tenderization see Tenderizing mechanisms, enzymatic Enzyme(s) as ingredients 1:301 in meat, chemical analysis 1:215–216 spoilage and see Spoilage, factors affecting Enzyme-linked immunosorbent assay (ELISA) definition 2:324, 2:367 detection of antibodies to Salmonella 2:369 Listeria monocytogenes detection 2:350 meat species determination 2:265–266, 2:268T Epidemiology, definition 2:405 Epigenetic reprograming (nuclear reprograming), definition 1:83 Epimysium 1:149–150, 1:154F definition and structure 1:321–322 function 1:321–322 Epinephrine see Adrenaline Epiphyseal plate closure 2:66, 2:80 Epithelium, definition 2:357 Equine species as intermediate hosts for parasites 3:40 see also Horse(s) Equipment laboratory, laboratory accreditation requirements 2:149 see also specific types of equipment Equipment cleaning 1:508–514 associated costs 1:508, 1:508T biofilms 1:513 evaluation of efficacy 1:513–514 inadequate, soil accumulation 1:508, 1:508F soil removal 1:508, 1:508F soil composition and 1:510–511, 1:511T strategies 1:511 surface energy 1:509–510, 1:510F see also Cleaning agents Equivalence 2:231 definition 2:231 risk management options assessment 3:231 Erythorbates 1:8–9, 1:419–420, 1:444, 3:80–81 Escherichia coli antimicrobial resistance 2:415 contamination, fresh meat 2:287 direct plating 2:315T enumeration 2:308 human foodborne infections 2:19 as indicator organism contaminated raw materials 2:287, 2:303 historical perspective 2:301

491

inadequate pathogen destruction processes 2:303–304 pathogenic see Pathogenic Escherichia coli (PEC) see also individual types Escherichia coli O104:H4 2:358 Escherichia coli O157:H7 2:19 bacteriophages 2:358–359 beef testing program 2:359 commercial test kits 2:360 control methods on-farm 2:360 during processing 2:360 detection 2:311 media used 2:311, 2:312T, 2:360 direct plating 2:315T ecology 2:359 enrichment procedure 2:313–314T enumeration 2:311, 2:313–314T sample size 2:311 foodborne outbreaks 2:19 gastroenteritis signs/symptoms 2:358 ground beef adulterant 2:358 irradiation effects 2:143 lineages 2:358–359 plating procedures 2:313–314T pre-enrichment procedure 2:313–314T refrigerated meat products 2:359 reservoirs 2:359 super shedders 2:359 vaccines 2:360 virulence clades 2:358–359 Esophageal cancer 2:101–102 Esophagus, tie and separation, cattle slaughter process 3:287 Essential oils 1:9, 1:305 definition 1:7 Estimated breeding value (EBV) calculation 1:23 definition 1:19 Estradiol in animal production 2:62 circulating levels 2:63 definition 2:62 fat synthesis/deposition 2:79–80 half-live 2:64 muscle growth effects 2:65, 2:78 muscle satellite cells, effects on 2:53 somatotropin and 2:65, 2:182 trenbolone acetate and 2:63 carcass protein 2:65, 2:66F muscle growth 2:65F zeranol vs. 2:62–63 Estradiol benzoate 2:62 Estrogen(s) in animal production 2:62 bone growth and 2:80 definition 2:62 muscle growth effects 2:65 pubertal growth and 2:53 Estrogenic, definition 2:62 Estrogenic hormones bone growth and 2:76 feed consumption stimulation 2:64 Estrogenic implants, dosages 2:63

492

Index

Estrogenic steroids, skeletal muscle growth effects 2:78 Ethical discussions, on animal welfare and slaughter, stereotypes 3:281, 3:281T Ethical quality, meat 1:366 Ethics, slaughter see under Slaughter Ethnic meat products Brazil and South America see Brazil and South America France see French meat products and dishes Germany see German meat products India and Pakistan see Indian subcontinent, meat products Japanese see Japan Korean see Korea Poland see Poland South African see Biltong Ethylenediaminetetraacetic acid, as secondary antioxidant 1:414 Ethylene vinyl alcohol, packaging film chemistry 3:21 Euphausia superba (krill) 3:381 Europe beef carcass classification/grading 1:307–309 livestock numbers 2:212T cattle 2:212T, 2:213 pigs 2:212T, 2:216 sheep and goats 2:212T, 2:214 pig carcass classification see Pig carcass classification, Europe waste management see Waste management, Europe Welfare Quality project see Welfare Qualitys European cattle 3:329–330, 3:358–359 European Food Safety Authority (EFSA) animal welfare risk-assessment 3:105 recommended maximum levels of smoke condensates 3:319 European Livestock and Meat Trading Union (UECBV) 3:148T European Natural Sausage Casings Association (ENSCA) 3:148T European Union (EU) animal by-products production rates 1:127 regulations 1:125 animal welfare legislation 3:103, 3:112 see also Welfare Qualitys antibiotic growth promotants policy 2:175T withdrawal 2:174, 2:174T beef carcass classification/grading system 1:307–308 classifiers 1:308 national legislation 1:308 CAP see Common Agricultural Policy (CAP) certifications/authentication systems German meat products 1:531, 1:532T Mediterranean meat products 1:551 intensive pig production legislation 2:217 meat and bone meal ban 1:134

nitrite regulations 1:200, 1:201T, 1:443, 3:223 nutritional labeling regulations 1:167, 1:168F organic meat production regulations 2:199, 2:200 pig carcass classification see Pig carcass classification, Europe rendering regulations 1:127, 1:128 steroid hormone ban 2:62 EUROP system 1:307–308, 1:307F, 1:316, 2:232, 2:234 conformation classes 1:307–308 definition 1:43, 2:231 fat cover assessment 1:307–308 Video Image Analysis mechanical grading 1:308–309 see also Pig carcass classification, Europe Eutectic plate cooling systems 2:238, 3:188 Eutectic solution, definition 2:236 Eutrophication 1:504 Evaporative chilling systems poultry carcasses 3:185 see also Spray chilling Evaporative condenser 3:200 Evaporator, mechanical vapor compression refrigeration 3:198–199, 3:200 Evisceration cattle 3:288 automation 1:48 definition 3:295, 3:303, 3:309 goats 3:311 patenting of apparatus 3:47 pigs 3:300 automation 1:44T, 1:46F bunging 3:300 midline and brisket opening 3:300 viscera and pluck removal 3:300 poultry 3:306 sheep/lambs 3:311 automation 1:50–52, 1:50T, 1:51F see also Bung dropping/bunging Exhaustion, meat canning operations 1:139 Exogenous enzymes, meat tenderization see Tenderizing mechanisms, enzymatic Exopolymeric substances (EPSs) 1:64 production, biofilm formation 1:65T, 1:67 Exotic animals 3:345–356 hide by-products 1:113T production systems 2:190–198 see also individual animals Expected progeny differences (EPDs) 1:23 bull assessment 3:331 calculation, meat quality traits 1:23 definition 1:19 Exports, meat 2:253 Exposure assessment 3:227–228 definition 3:214, 3:216, 3:217F see also Risk assessment Exsanguination 1:561–563 animal welfare concerns 1:562 blood loss 1:562–563 blood pressure 1:562 blood retention 1:562–563

brain function loss, time to 1:562 carcass quality 1:563 cattle slaughter 1:562, 3:285 cause of death 1:561 cerebral perfusion 1:562 definition 1:561, 1:561, 3:280, 3:309 loss of consciousness 1:562 delayed 1:562 meat quality and 1:563 pain during 1:562 pigs, effects on meat quality 1:368 poultry 3:305 sheep and goats 3:310–311, 3:311F slaughter without stunning 1:561–562 techniques 1:561–562 see also Stick/sticking Extenders 1:1–6, 1:299–300 addition to meat products 1:2 functional properties 1:2, 1:2T ingredients 1:3 animal-derived 1:5 flavorings and colorings 1:5 functional components 1:2–3, 1:3T gums and hydrocolloids 1:5 inulin and oligofructose 1:4–5 milk ingredients 1:3–4 soy ingredients 1:3 starch ingredients 1:4 see also Nonmeat proteins Extensive production/farming cattle see Cattle production systems definition 2:190 sheep 2:214, 2:214F, 2:215F External heating methods, thawing see Thawing Extraction see under Chemical analysis methods Extraintestinal pathogenic Escherichia coli (ExPEC) 2:357 Extrinsic factors definition 2:345 in preservation 2:345 Extrinsic foreign bodies, in meat definition and implications 2:22–23, 2:23T see also Foreign bodies Extruder screw, definition 1:564 Extrusion, definition 3:241 Extrusion cooking 1:388, 1:565–567 acrylamide formation 1:568–569 definition 1:564 single-screw extruders 1:566–567, 1:566F twin-screw extruders 1:567, 1:567F Extrusion technology 1:564–569 coextrusion see Coextrusion cold extrusion see Cold extrusion economics 1:569 hot extrusion see Extrusion cooking meat analogs 1:568 thermoplastic starch 1:568 see also Sausage casings Exudate, subjective scoring 2:166 Eye movements, definition 3:413 Eye white response, stress 3:85

Index

F Fab area 1:458 Fabricate (meat cutting), definition 1:458, 1:458 Fabric casings, sausages 3:239 Fab room 1:458 Failure mode and effects analysis (FMEA) 2:92, 2:97 definition 2:92 optimization measures 2:98 practical approach 2:97 risk assessment 2:97–98, 2:98T structured failure analysis 2:97, 2:97F Fallow deer 2:193 FAMACHA 2:475, 2:476T definition 2:471 Fans, ovens 3:138–139, 3:138F Fan ventilation, chicken meat production systems 2:206, 2:206F, 2:207F Farm(s) nutrient balance 2:153 Salmonella control and preventive measures see under Salmonella thermotolerant Campylobacter control strategies 2:386 see also Production systems Farmed fish processing procedures 1:147 product quality, assessment of effects of stunning/killing 3:424–425 slaughter process 3:422 steps 3:422, 3:423F stunning and killing see Farmed fish, stunning and killing welfare 3:421 certification schemes and 3:425 Fish Welfare Assurance System (FWAS) 3:425 welfare aspects of stunning/killing 3:423–424 see also Aquaculture; Finfish; Fish Farmed fish, stunning and killing 3:421–426 assessment 3:423–424 physical measurements 3:424 product quality 3:424–425 welfare aspects 3:423–424 control of process 3:425 ethical aspects 3:283 methods 3:422, 3:422–423, 3:423F Aqui-STM 3:422–423 electrical stunning 3:411, 3:422, 3:423F percussive stunning 3:422, 3:423F Farmed game definition 3:345, 3:345 see also Game Farming systems as driver of meatborne parasite transmission among farmed animals and to humans 3:41 see also Production systems Farrowing crates animal welfare 3:104–105 definition 3:102 Fascicles, muscle 1:323, 1:324–325

Fasciculus, definition 2:70 Fasciola hepatica 3:34–39, 3:35–38T, 3:40 Fast-fermented sausages 3:249 see also Dry/semidry sausages Fast food outlets, thermotolerant Campylobacter control 2:387 Fast freezing of meats 2:227 Fasting preslaughter, pigs 1:366 before transport 3:96 Fast-twitch fibers distribution in muscles 1:161F functions 1:155 innervation 1:155, 1:160F myosin ATPase activity 1:155, 1:160F see also Muscle fibers (myofibers) Fat 1:206, 1:239–241 aerobic spoilage, factors affecting 3:390 animal-derived 1:130 carcass see Carcass fat characteristics, emulsion/batter stability and 1:286 consumption, concern over 2:449–450 cancer and 2:122 consumption by food (and country) 2:113T content (meat) 1:180, 1:206, 1:222, 2:113–115, 2:115F analysis see Fat analysis methods animal domestication affecting 3:361 different countries 2:111 distribution/sites 2:114 double-muscled animals 1:467T, 1:469 effect on content of other components in meat 1:235, 1:236F factors affecting 1:241 changes from birth to maturity 1:236, 1:236T, 1:241 species differences 1:237T increases, lipid type changes 2:114 lean beef 2:107, 2:108T, 2:112 meat palatability and 1:159, 1:222, 1:223F, 1:252–253, 1:253F poultry meat 2:112 types of fats 2:114 window of acceptability 1:222, 1:223F deposition patterns 2:59 gender differences 2:59 genetic variation 2:60 nutrition effects 2:60 see also Growth patterns dietary, leaner carcass production in poultry and 2:469 digestion, ruminants 2:472–473, 2:473F fatty acid composition of animal fat 1:130, 1:132T in human diet 2:121–122 cancer and 2:122 intermuscular see Intermuscular fat intramuscular see Intramuscular fat in meat products nutritional composition of reduced-fat products 2:451–452 reduction strategies 2:451, 2:452T role 2:450–451, 2:450F

493

melting point 1:240, 1:240T peroxidation heme iron effect, cancer and 2:122–123, 2:122F see also Lipid oxidation quality, pigs 3:367 reduction, low-fat meat batter 1:287 requirements, poultry 2:464T, 2:465 softness, pork, measurement 2:492 subcutaneous see Subcutaneous fat see also Adipose tissue; Fatty acid(s); Lipid(s); Lipogenesis; Triacylglycerols (triglycerides) Fatal familial insomnia (FFI) 2:366 Fat analysis methods 1:181, 1:182T, 1:206–208, 1:207F additional methods 1:181–183, 1:182T microwaves, meat quality measurement 2:494 official methods 1:181, 1:182T rapid methods 1:182T, 1:183 see also Fatty acid analysis Fat cell(s) see Adipocyte(s) Fat depots 2:79 Fat-free meat product, patenting 3:45 Fat-holding properties, nonmeat proteins 1:289–290 Fatliquoring, leather 1:122 Fat replacer 2:451 Fat-soluble vitamins, in meat, chemical analysis 1:212 determination 1:212–213 extraction and purification 1:212 Fat substitutes 2:451 Fatting out (emulsion failure) 3:259 Fat tissue see Adipose tissue Fatty acid(s) 1:239–240 adipocytes, uptake by 2:47 composition animal-derived fats 1:130, 1:132T importance 2:114 of meat 2:114, 2:115–116, 2:115F of meat, by animal type 2:116, 2:116T species differences 1:241 see also Lipid(s), fatty acid composition desaturation 1:230, 1:230F esterification 2:47 free, definition 2:79 melting point characteristics 1:240, 1:240T nomenclature 1:240 nutritional enhancement of meat 2:452 oxidation 3:395, 3:395F positional distribution in meat 2:114–115 requirements, poultry 2:464T, 2:465 trans fatty acids see TFA (trans fatty acids) see also Monounsaturated fatty acids; Polyunsaturated fatty acids (PUFAs); Saturated fatty acids; Unsaturated fatty acids Fatty acid analysis 1:208 gas chromatography 1:208–209 isolation of free fatty acids 1:208 methylation 1:208 special procedures for trans fatty acids 1:209 Fault tree analysis (FTA) 2:92

494

Index

Fear, capability of fish to experience 3:343 Feather(s) removal 3:306, 3:306F rendering 1:128 Feather bones automatic removal, pork middles 1:34, 1:36F definition 1:33 Feather meal (hair and feather meal) 1:135 Fecal contamination, detection 2:22, 2:22T Feed(s) beef quality assurance (BQA) guidelines 3:174, 3:175T composition/ingredients animal by-products 1:129–130 optimization 3:428 poultry see Poultry feed formulations contaminants, Salmonella 2:371–372 definition 3:215 formulated, definition 2:204 influence on manure nutrients see Manure nutrients, influence of feeds intake double-muscled animals 1:467, 1:467T residual, definition 3:328 see also individual animal species Feed additives beef quality assurance (BQA) guidelines 1:73–74, 3:175T beta-agonists see Beta-adrenergic agonists (BAA) poultry feed formulations 2:466–468, 2:467T reduction of methane production in ruminants 1:73 residues 3:217–218 Feed conversion rate (FCR) definition 3:427 improvement 3:427–428 Feed digestion, ruminants see Ruminants Feed efficiency definition 2:172 net, definition 3:328 Feed fermentation, rumen 2:471–472 see also Ruminants, feed/feeding Feed-grade animal fat see Yellow grease Feeding organic livestock production, guidelines 2:199, 2:200 pigs see Pig nutrition poultry see Poultry nutrition ruminants see Ruminants Feeding programs, poultry 2:466–468 Feeding systems, chicken meat production systems 2:207–208, 2:208F Feedlot, definition 3:102 Feed medication programs, pigs 2:187 Feed residues 3:216–217 Feet removal, poultry 3:306 Feline spongiform encephalopathy 2:364 Female hormones, pubertal growth 2:53 Femur, calf, structure 1:165F Fenton reaction 2:121 Feral, definition 2:190 Fermentation definition 2:405

feed, rumen 2:471–472 see also Ruminants, feed/feeding Fermentation, meat 1:305 developments 2:1–2 microorganisms involved and use of starter cultures 2:3 lactic acid bacteria 1:76, 2:1, 2:3 Fermented meat products molds 2:402 yeasts 2:402 see also specific products Fermented sausages bacteriocin application 1:79 biogenic amines in see under Biogenic amines classification 3:248 development of sensory quality 2:4 color 2:4 effect of processing 2:5 flavor 2:4–5 texture and mouth-feel 2:4 drying room 1:477F as ’functional meat products’ 2:7 fungi in 2:402 German 1:531T, 1:533–534 GreuXener salami see GreuXener salami Ru¨genwalder Teewurst see Ru¨genwalder Teewurst historical aspects 2:1 microbial stability and safety 2:5–6, 3:253–254 modeling nature/dynamics of ripening 2:5T, 2:6–7, 2:6F nitrosamines in 3:224 processing 2:2 comminution/chopping 2:2 effect on sensory quality 2:5 raw materials and additives 2:2 ripening 2:2, 2:2–3 smoking 2:3, 3:325 stuffing 2:2 sausage metabolism and pH 2:3–4 use of starter cultures 2:3, 3:248, 3:248–249 see also Dry/semidry sausages Ferrihemochrome 1:248–249, 1:249T Ferrimyoglobin peroxide 1:247T, 1:248 Ferritin, definition 2:135 Ferrocholemyoglobin 1:248 Ferrylmyoglobin 3:398 definition 3:394 Fertility, double-muscled animals 1:467T, 1:468 Fertilizers, environmental impacts 1:503 eutrophication 1:504 nitrogen 1:503 phosphorus 1:504 Fetal growth endocrinology 2:49–50 gene imprinting 2:49–50 insults/negative influences, permanent endocrine changes 2:50 placental growth factors 2:51–52 Fetal origin of disease (Barker hypothesis) 2:52

Fibre, nutritional enhancement of meat products 2:452–453, 2:453T Fibrous casings, sausages 3:238–239 Ficin 1:301, 3:441 Figures of merit 1:188–189 definition 1:187 Fillers 1:299–300 Films, packaging see Packaging films Fimbriae, definition 2:340, 2:357 Final product, composition for labeling, analysis see Chemical analysis, final product composition for labeling Fin cutting 3:300 Finfish 3:336–344 definition 3:336 nutritional content 3:336–342, 3:342T shellfish vs. 3:369 potential health issues associated with 3:342 processing 3:342 production capture (wild) production by principal species 3:336, 3:337–339T world aquaculture production 3:336, 3:340–341T, 3:421 welfare issues 3:342–343 see also Farmed fish Finishing beef cattle see Beef cattle, finishing definition 3:328 double-muscled animals 1:468 pigs see Pig(s), finishing Finite element method, definition 3:202 Finland, meat research institutions national 2:255–256T provincial 2:257–261T Fish definition 3:336 environmental contaminants dioxins/polychlorinated biphenyls, concentrations 1:499 trace elements 1:499–500 freezing, effect on product quality 3:194 freshness assessment see Fish inspection fungi in 2:402T hazardous components/factors compromising functionality and safety 2:9T assessment see Fish inspection classification of hazard factors 2:9T immobilization 3:419 minced 2:271 composition 2:272 safety 2:274 uses 2:272 washed see Surimi nonfinfish 3:343 off-flavor development 1:413 processing 1:147 slaughter see Farmed fish, slaughter true definition 3:336 see also Finfish see also Farmed fish Fisheries production 3:336 see also Farmed fish; Finfish

Index

Fish inspection 2:8–16 freshness assessment and its evaluation 2:8–9, 2:10T chemical methods 2:9, 2:10T measurement of adenosine-50 triphosphate (ATP)-related compounds and use for freshness assessment 2:9–11 measurement of K value by paper electrophoresis (’freshness checker’) 2:11, 2:11F, 2:12F nondestructive assessment by nearinfrared and phosphorus-31 nuclear magnetic resonance 2:11 overview of adenosine-50 triphosphate (ATP)-related compounds of fish postrigor 2:9, 2:10F microbiological methods 2:10T, 2:14 quick detection and counting of histamine-forming bacteria 2:14, 2:15F physical methods 2:10T, 2:11–13 electrical sensors 2:13 rigor index 2:11–13, 2:12F texture 2:13 sensory method 2:9, 2:10T safety assessment 2:13–14 determination of histamine by paper electrophoresis (’histamine checker’) 2:14, 2:14F histamine intoxication 2:13–14 Fish meal 1:135–136 future availability 1:135–136 Fish oils 1:133, 2:133 fatty acid composition 1:132T, 1:134T Fish oil tanning 1:121 Fish welfare see Farmed fish, welfare Fish Welfare Assurance System (FWAS) 3:425 Five freedoms 3:102, 3:109 Flagella, biofilm formation role 1:67 Flags, as driving aids 3:87 Flaking equipment 2:422, 3:130 Flame sterilization 1:386 Flare fat, definition 1:43 Flavor(s) 1:377, 1:391, 3:267–268 animal muscles’ contribution to 1:302 chemical development 1:258 cured meats see Cured meats, flavor definition 1:252, 1:391 detection of 1:302 chemical detection 1:260 development see Flavor development effect of cooking 1:374–375 factors affecting, sheep and goats 3:376–377 heat effects see Flavor development, heatinduced meat flavor; Maillard reaction irradiation effects 2:142 lipid content influencing 1:258, 2:446 makeup of (taste and odor) 1:377–378 masking, warmed-over flavor prevention 1:414–415 measurement 1:260

trained sensory panels 1:260 see also Sensory assessment, meat meat fiber types affecting 2:446 precursors 1:377 reactions 1:258 role of fat 2:451 sensory evaluation 1:260 beef 3:276–277 lamb 3:276–277 pork 3:276, 3:276F examples of references used for training of panelists 3:277T see also Sensory assessment, meat species-specific 1:259 volatile compounds and 1:391, 1:392F see also Maillard reaction; Volatile compounds see also individual meats; Sensory aspects of meat quality; Warmed-over flavor (WOF) Flavor aromatics, perception 1:258 Flavor development 1:377–384 dry sausages 3:250–252, 3:253T fermented sausages 2:4–5 heat-induced meat flavor 1:378–379, 1:383, 1:383F derived from decomposition of individual substances 1:378–379 derived from interaction between lipid oxidation and Maillard reaction products 1:379–380 derived from lipid oxidation 1:379 derived from Maillard reaction/ advanced glycation end products 1:379 effect of animal’s diet 1:380 species effects 1:380 see also Lipid–Maillard interactions; Maillard reaction nitrite-cured meat 1:381–383 precursors of meat flavor 1:377 see also Flavor Flavorings/flavoring agents 1:9–10, 1:300, 1:302–306 characteristics 1:302–305 commonly used 1:303–304T components 1:302–305 as meat extenders 1:5 natural 1:433 use in cured products 1:444 Flaxseed oil 2:133 Fleischwurst (Vienna Bologna) 3:243 Flight zone 3:86, 3:97, 3:97F definition 3:84, 3:172 pigs 3:86, 3:171–172 Flooring surface, stockyards 3:92–93 Flour, as coating 3:119 Flour products 1:299 Flow injection analysis (FIA) 1:177 FMEA see Failure mode and effects analysis (FMEA) Foam cells 2:105 Focal myopathy 1:344 Folates, in meat, chemical analysis 1:214 Follistatin 1:466 myostatin inhibition 2:50–51

495

Following behavior, use of 3:87 Food, functional see Functional food(s) Food and Agriculture Organization of the United Nations (FOA) definition 2:211 finfish production data capture (wild) production 3:336, 3:337–339T world aquaculture production 3:336, 3:340–341T Food and Drug Administration (FDA), food irradiation regulation 2:141 Foodborne disease, definition 2:17 Foodborne pathogens Aeromonas see Aeromonas Clostridium botulinum see Clostridium botulinum Clostridium perfringens see Clostridium perfringens control/prevention see Foodborne pathogens, control measures DNA subtyping 2:297 DNA macrorestriction band-based 2:297–298 pulsed field gel electrophoresis see Pulsed field gel electrophoresis (PFGE) ribotyping 2:298–299 DNA sequence-based 2:299 multilocus sequence typing see Multilocus sequence typing (MLST) multiple-locus variable-number tandem repeat analysis see Multiple-locus variable-number tandem repeat analysis (MLVA) single-nucleotide polymorphism genotyping 2:299–300 Listeria monocytogenes 2:350–351 polymerase chain reaction-based 2:297 emerging see Emerging pathogens Listeria monocytogenes see Listeria monocytogenes molecular detection 2:294–295 isothermal detection 2:296 microarray/gene chip 2:296–297 polymerase chain reaction see Polymerase chain reaction-based detection, foodborne pathogens RNA detection 2:296 Salmonella see Salmonella Staphylococcus aureus see Staphylococcus aureus Yersinia enterocolitica see Yersinia enterocolitica see also Foodborne zoonoses Foodborne pathogens, control measures Aeromonas 2:320 Clostridium botulinum see Clostridium botulinum, control in meats Clostridium perfringens 2:338–339 Listeria monocytogenes 2:354–356, 2:355T Salmonella see under Salmonella

496

Index

Foodborne pathogens, control measures (continued) Staphylococcus aureus 2:380 thermotolerant Campylobacter see Thermotolerant Campylobacter, control measures Yersinia enterocolitica 2:410 Foodborne zoonoses 2:17–21 definition 2:17 emerging foodborne pathogens see Emerging pathogens infective pathways 2:17 zoonotic agents associated with meat 2:17–18, 2:18T Campylobacter 2:17–18 Clostridium perfringens 2:18–19 see also Clostridium perfringens, foodborne disease Escherichia coli 2:19 Listeria monocytogenes 2:19 see also Listeriosis Norovirus 2:20 Salmonella 2:18 see also Salmonellosis Yersinia enterocolitica 2:19–20 see also Yersiniosis see also Foodborne pathogens; Zoonoses/ zoonotic disease Food chain assessment 3:216 definition 3:214 origin of chemical residues in meat and 3:215, 3:215F Food contact surfaces characteristics 1:509, 1:509T cleaning see Equipment cleaning definition 1:508 Food distribution, thermotolerant Campylobacter control during see under Thermotolerant Campylobacter Food handling, antimicrobial resistance considerations 2:415 Food irradiation 2:140, 3:81–82 applications 2:143–144 approved uses 2:143 biological organisms, effects on 2:143 costs 2:144 definition 2:140, 2:140, 3:78 detrimental effect reduction methods 2:142 foodborne illness control 2:142 as hurdle technology 2:346–347 insect damage control 2:142 meat color, effects on 2:142 meat industry adoption of 2:144 meat quality and 2:142 microorganisms, effects on 2:143 muscle foods 2:142 consumer demand, lack of 2:144 meat flavor, effects on 2:142 pasteurization vs. 2:141 for preservation 2:142 process 2:142 requirements 2:141 processed meat decontamination 2:281–282, 2:290–291

radiation sources 2:141 regulation 2:141–142, 2:281–282 sprouting/ripening control 2:142 sterilization 2:142 uses 2:142–143 Food production environment, surfaces characteristics 1:508–509, 1:509T cleaning see Equipment cleaning Food protein-derived bioactive peptide definition 2:32 see also Functional food(s) Food quality estimation 2:8, 2:8T extruded food 1:568–569 see also Meat quality Food retailers, animal welfare standards 3:103 Food safety animal welfare 3:103 cloning 1:89 definition 3:216 genetically engineered animals 1:95–96 market specifications and 2:231–232 muscle fiber types and 2:447 Food Safety Objective (FSO) 3:232 definition 2:430, 3:226 Food storage, antimicrobial resistance considerations 2:415 Foot-and-mouth disease African ungulates 3:349 legal frameworks and standards 2:219 surveillance and interventions for hazard reduction 2:222 Foot-and-mouth disease virus (FMDV), meat pH and 1:29 Forced-air convection ovens 1:387, 3:134–136, 3:134F see also Cooking processes Forced convection air chilling 3:180 definition 3:131 Forcing pen, layout 3:91 Foreign bodies 2:22–31 definition and implications in meat extrinsic foreign bodies 2:22–23, 2:23T intrinsic foreign bodies 2:22, 2:22T detectability definition 2:22 determination 2:29F, 2:30–31 detection limit definition 2:22 determination of specific detection limit 2:28–31, 2:28F, 2:29F legislation and consumer demands 2:23 risk assessment 2:23 technologies for detection in meat 2:23–24 electromagnetic contrast 2:25–28, 2:27F heterogenous product 2:27–28 idealized situation 2:27, 2:28F emerging technologies 2:31 dual-energy X-ray 2:29F, 2:31 hyperspectral vision 2:31 medical X-ray modalities 2:30F, 2:31 X-ray contrast 2:24–25, 2:24T, 2:25F, 2:26F

Hounsfield scale/units 2:24, 2:24T X-ray scanning and metal detection 2:23–24, 2:24F Forequarter pistola cut automated 1:37 definition 1:33 Forestomachs, ruminants 2:471, 2:471F, 2:472F Formed hams 1:447–448, 1:448T Forming equipment 3:116, 3:117F Formulated feed definition 2:204 see also Feed(s) Fortified sample material, definition 1:217 FOSHU (foods for specified health use) 2:33 definition 2:32 functional meat products 2:33 representative ingredients 2:33T see also Functional food(s); Nutraceuticals Fourier equation, refrigeration process modeling 2:438, 2:438F, 2:439 France meat products and dishes see French meat products and dishes national meat research institution 2:255–256T Frankfurters 1:534–535, 3:243–245, 3:259 preparation/production 1:449–450, 3:132, 3:132F smoking procedure 3:318F, 3:318T, 3:325–326 spices used 1:306T see also Frankfurter Wu¨rschten Frankfurter Wu¨rschten 1:534–535 definition 1:530 manufacturing process 1:534–535, 1:535F see also Frankfurters Free cholesterol 1:230 Free convection, definition 3:131 Free fatty acids definition 2:79 see also Fatty acid(s) Free radicals definition 3:394 irradiation-induced 2:142 Free-range systems, chicken meat production 2:204, 2:204F, 2:205, 2:205, 2:205F Freeze-dried products 1:476 Freeze dryers 1:475–476, 1:476F Freezer burn 1:410, 3:192 definition 3:191 Freezing 2:227, 3:79 carcasses 2:227 sheep and goats 3:313 thermotolerant Campylobacter control 2:386 cold chain 2:227 definition 3:178 fast freezing 2:227 ice crystal growth 3:181, 3:461 meat quality degradation 3:181 ice recrystallization 3:181 meat aging and 1:336 meat surface appearances 3:182

Index

methods 3:181–182 effects on hamburgers 2:227 muscle, effect on rigor mortis 1:361–362 plate see Plate freezing as predrying treatment 1:474 process 3:178, 3:181 process models freezing heat loads 2:440–441 freezing times 2:437–440, 2:439F storage lives of frozen meat/meat products 3:194–195, 3:195T technology applications 3:178–183 principles 3:196–201 see also Refrigeration equipment temperature see Freezing temperature see also Frozen storage; Thawing Freezing, effect on product quality 3:191–195 fish and seafood 3:194 poultry 3:194 red meat appearance 3:192–193, 3:193F eating quality 3:193–194 freezing process 3:192 frozen storage 3:192 microbiological quality and safety 3:194 packaging before freezing 3:191–192 thawing process 3:192 Freezing front 3:181 Freezing point depression, definition 3:202 Freezing rate, definition 3:191 Freezing systems see Refrigeration equipment Freezing temperature 3:461–462 definition 3:178, 3:460 ice crystal formation 3:461 meat composition effects 3:461 profiles 3:181, 3:181F Freezing–thawing meat tenderization and 3:450 see also Freezing; Thawing Frenched racks, definition 1:33 French Label Rouge system 2:202 French meat products and dishes 1:527–529 braised meat courses 1:527 with beef/bull 1:527 with game 1:528 with innards 1:528 with pork 1:528, 1:528F with rabbit 1:528 with veal 1:527–528, 1:528F charcuterie (delicatessen) 1:528 blood sausage or black pudding/white boudin (boudin noir/boudin blanc) 1:529 cooked ham/jambon de Paris 1:528–529, 1:529F definition 1:527 dry-cured ham/jambon sec 1:529 dry sausages/saucisson et saucisse se`che 1:528, 1:551 paˆte´s/terrines/rillettes 1:529 French-style leg, lamb 1:463 Fresh meat

bacteriocin application 1:79–80 color 3:27–28, 3:27F see also Meat color decontamination 2:276–279, 2:287–288 chemical treatments 2:277–278 definition 2:276 temperature-based treatments 2:276–277 see also Biopreservation pigments see Pigments see also Meat Fresh meat, microbial contamination 2:285–288 coliforms 2:287 detection of microbial contaminants 2:286 generic Escherichia coli 2:287 indicator tests for pathogen contamination 2:286, 2:302–303 microbiological criteria 2:287 processes to reduce contamination on meat carcasses and cuts 2:287–288 see also Fresh meat, decontamination sources of microbial contaminants 2:285–286 chilling 2:286 cutting 2:286 dressing 2:286 slaughtering 2:285–286 total viable counts 2:286–287 Freshness assessment, fish see Fish inspection Freshness Checker (fish freshness) 2:11 Fresh sausage additives and seasonings 3:262, 3:263T beef 3:261 American 3:264 European 3:264 casings 3:262 definition 3:241, 3:261, 3:261–262 pork 3:261, 3:262, 3:262–264 additives/seasonings 3:263T American 3:264 European 3:264 finished form 3:265T processing 3:265T spices used 1:306T production and types of sausage 3:262–265, 3:264F finished form of different sausage types 3:265T processing examples 3:265T raw materials 3:262 see also Emulsified sausages; Sausage(s); specific types of fresh sausage Frog’s legs 2:197 Frost point, definition 3:50 Frost-point generator, hygrometer calibration 3:53 Frozen fraction, definition 3:202 Frozen meat breakers 3:130 irradiation effects 2:142 retail display 2:229 storage 2:228 see also Frozen storage storage life 2:228

497

thermal conductivity 3:463 transport see Transport of meat/meat products vacuum packaging 3:31–32 yeast flora 2:400 Frozen raw material, refrigerated raw material vs., dry-cured ham production 2:88 Frozen storage effect on product quality 3:192 mold growth 2:401 storage lives of frozen meat/meat products 3:194–195, 3:195T see also Freezing; under frozen meat Frozen wrapped products, display cabinets 3:189, 3:189F Fructooligosaccharides, definition 2:118 Fryers, deep fat 3:120–121, 3:120F Frying hot fat/oil 1:388 role in coating systems (battering/ breading) 3:116 equipment (fryers) 3:120–121, 3:120F FSO (Food Safety Objective) see Food Safety Objective (FSO) Fukushima, as incident resulting in contamination of food with radionuclides 1:501 Fumaric acid 3:80–81 Functional food(s) 2:32–36 definition 1:289, 2:32, 2:32 development of novel functional meat products 2:35 meat protein-derived bioactive peptides 2:35, 2:35T probiotics, prebiotics, and synbiotics 2:35 future prospects 2:35–36, 2:36T meat-based bioactive compounds 2:33–34, 2:34F conjugated linoleic acid 2:34–35, 2:34F, 2:132 histidyl dipeptides 2:34, 2:34F L-carnitine 2:34, 2:34F, 2:131–132 see also Nutraceuticals meat products 2:33 approaches for functional modification 2:34T definition 2:32 overview 2:32–33 regulation 2:33 representative ingredients 2:33T see also FOSHU (foods for specified health use) Functional genomics 1:17–18 Functional ingredients, meat products 1:7–11 addition methods 1:7 regulations 1:7 types 1:7 acidifiers 1:10–11 antimicrobials 1:10 antioxidants 1:10 erythorbate 1:8–9 flavorings 1:9–10 nitrate see Nitrate nitrite see Nitrite

498

Index

Functional ingredients, meat products (continued) phosphate 1:8 salt 1:7 seasonings 1:9 sweeteners 1:9 tenderizers 1:10 see also Curing; Curing agents; Natural curing; Nonmeat proteins; specific ingredients; Tenderizing mechanisms, chemical Functionality definition 1:267, 1:289 see also Muscle proteins, functionality Functional properties definition 1:289 nonmeat proteins in comminuted meat products see Nonmeat proteins Fungi 2:395 classification 2:395 in muscle foods 2:402T, 2:403–404T Fungi imperfecti (deuteromycetes) 2:395 Furan-like sulfur compounds, formation via Maillard reaction 1:397–398, 1:398F, 1:399F Furans, formation via Maillard reaction 1:397 Fusarium 2:395, 2:398F F-value, heat treatment 1:140

G Galbi (Korean dish) 1:546F, 1:547 Gallstones, treatment 2:131 Gambrelling, pig carcasses 3:299 Game 3:345–356 definition 3:345 economics 3:346 meat consumption 3:346 definition 3:345, 3:345–346 French dishes 1:528 increased demand motivators 3:346 production 3:346 Africa 2:194, 3:346 see also individual animals/meats Game birds 3:346–347, 3:347, 3:373 captive-bred 3:347 definition 3:345 lead shot residues 3:347 meat proximate composition 3:347, 3:348T production systems 2:192, 3:373 Gamma-irradiation Aeromonas control 2:320 Bacillus cereus control 2:328 see also Food irradiation Gamma radiation, definition 1:515 Gang tag, cattle head 3:287 Gas(es) condensable, definition 3:315 noncondensable, definition 3:315 packaging role see under Modified atmosphere packaging (MAP)

Gas chromatography 1:176–177 fatty acid analysis 1:208–209 veterinary drug residue analysis 1:219, 1:219T Gas chromatography–mass spectrometry definition 1:410 warmed-over flavor 1:412 Gas fermentation, sugar use 1:297–298 Gas mixtures, for stunning/killing 3:402 Gas packaging, vacuum packaging vs. 3:29 Gas permeability, modified/controlled atmosphere packaging 3:11 Gas stunning 1:368, 3:401–406 commercial implications 3:404–405 electrical stunning vs. 3:401 gas mixtures evaluated for stunning/killing 3:402 mechanisms of induction of unconsciousness 3:402 pigs 1:368, 3:297–298, 3:401–402 poultry 3:304, 3:401, 3:419 reasons for use 3:401–402 time to onset of unconsciousness during exposure to gas mixtures 3:402–403 welfare concerns 3:403–404 gas mixture aversion studies 3:403, 3:403F severity of respiratory distress 3:403–404, 3:403F see also Stunning Gastroenteritis Clostridium perfringens type A 2:335, 2:337 see also Clostridium perfringens definition 2:17, 2:317, 2:335 pathogenic Escherichia coli 2:357, 2:357T Gastrointestinal microbiota composition changes, antibiotic growth promotants 2:173 see also Commensal bacteria Gastropods 3:385 Gates, powered, in stockyards 3:93 GDF8 see Myostatin gene (GDF8) GDL (glucono-delta-lactone) 1:11, 1:298, 3:80–81 Geese 3:372 farming 2:192 meat see Goose meat slaughter process 3:293 Gel, definition 1:137 Gelatin as meat extender 1:5 pork skin use 1:115 uses 1:299 Gelatinization 1:239 Gelation 1:270 adhesive role of gels 1:270 definition 1:267, 1:270 effect of processing protocols 1:271 gelling properties from different muscles and fiber types 1:271, 1:272F meat emulsion/batter stability and 1:285–286 mechanism of gel formation 1:270–271, 1:271F myosin and mixed myofibrillar protein gels 1:270

role of different muscle proteins 1:270 role of nonmeat proteins 1:290–291 Gelbvieh 3:329–330 Gel electrophoresis, as proteomics tool 3:155 Gender animals see Sex (animals) humans, vegetarianism and 2:138–139 Gene chip technology, detection of foodborne pathogens 2:296–297 Gene expression analysis 2:40–41 Generalized epileptiform activity, definition 3:407 Generalized epileptiform insult definition 3:421 following stunning of farmed fish 3:423–424 GeneSTARs 2:38 Gene targeting, nuclear transfer and 1:91 Genetic(s) domestication of animals 3:361 influence on sensory aspects of meat quality 3:268 Genetically engineered, definition 1:92 Genetically engineered animals 1:92–96 current examples 1:94–95 food safety/approval 1:95–96 future direction 1:95 use in meat production 1:94 see also Transgenic animals Genetically modified organisms (GMOs) definition 1:92, 1:92 in meat animal production see Genetically engineered animals Genetic markers see DNA markers Genetic selection programs 1:22–25 improvement of carcass composition, use of imaging techniques 1:23, 1:23F improvement of meat quality 1:23 sire referencing scheme 1:24–25, 1:24F see also DNA markers; Marker-assisted selection Genetic variation, growth patterns 2:60 Gene transfer, horizontal, definition 2:294 Genome scan, quantitative trait loci, carcass and meat quality traits 1:15, 1:15T Genome-wide association studies 1:17–18, 2:40 Genomic(s) breeding value, definition 1:12 cattle industries 3:331 comparative 2:40 definition 1:97 functional 1:17–18 see also Genomic technology/modern genetics, application in meat industry Genomic selection 1:17, 1:17F, 1:17T definition 1:12 pedigree/phenotypic data and 1:17, 1:17F Genomic steroid actions 2:64 definition 2:62 Genomic technology/modern genetics, application in meat industry 2:37–42 beef 2:37–38 candidate genes 2:40

Index

gene expression analysis 2:40–41 genome-wide association studies 2:40 linkage disequilibrium 2:41 marbling 2:39 meat tenderness 2:37 muscle fiber biochemistry 2:39–40 pork 2:38–39 poultry 2:39 proteomics and 2:41 traceability 2:41 see also DNA markers; Genomic(s) Genotoxic, definition 3:315 Geographic conditions, red meat animal production systems and 2:211, 2:212T Geotrichum 2:395, 2:399F German meat products 1:530–537 classification 1:531T dry-cured ham 1:531–532, 1:531T Ammerla¨nder Knochenschinken see Ammerla¨nder Knochenschinken Schwartzwa¨lder Schinken see Schwartzwa¨lder Schinken (Black Forest ham) Westfa¨lischer Knochenschinken see Westfa¨lischer Knochenschinken European Union authentication systems 1:531 Protected Geographical Indication 1:531, 1:531T sausages see German sausages typical products 1:531F German sausages 1:531T cooked 1:530, 1:531T blood sausages 1:536–537, 3:246 Thu¨ringer Rotwurst see Thu¨ringer Rotwurst emulsion-type sausages 1:531T, 1:534 Frankfurter Wu¨rschten see Frankfurter Wu¨rschten Halbersta¨dter Wu¨rschten see Halbersta¨dter Wu¨rschten Mu¨ncher WeiXwurst see Mu¨ncher WeiXwurst Pfa¨lzer Saumagen see Pfa¨lzer Saumagen liver sausages 1:531T, 1:535–536 Pfa¨lzer Leberwurst see Pfa¨lzer Leberwurst Thu¨ringer Leberwurst see Thu¨ringer Leberwurst fermented 1:531T, 1:533–534 GreuXener salami see GreuXener salami Ru¨genwalder Teewurst see Ru¨genwalder Teewurst for frying 1:531T, 1:537 Nu¨rnberger Rostbratwurst/Nu¨rnberger Bratwurst see Nu¨rnberger Rostbratwurst/Nu¨rnberger Bratwurst Thu¨ringer Rostbratwurst see Thu¨ringer Rostbratwurst Germany, meat research institution 2:255–256T Germfree animals, antibiotic growth promotants 2:173

Gerstmann–Stra¨ussler–Scheinker syndrome (GSSS) 2:365–366 Ghee, definition 2:190 GHG see Greenhouse gases Giblets as edible by-product 1:111 salvage 3:307 Gilts carcass composition 3:363–364 see also Pig(s) Glass definition 3:462 as foreign body in meat 2:23, 2:23T detection 2:25 as surface in food production environments/equipment 1:509T Glass containers, heat processing and 1:386 Glass electrodes, pH measurement 1:264–265, 1:264F Glass transition 3:462 Glass transition temperature 3:462 Global warming 1:71 definition 1:71 indicators of changing climate 1:505–506 see also Environmental impact, meat production Global warming potential (GWP) 1:502, 1:504 Globin 1:244, 1:244F denaturation during cooking 1:248–249 see also Myoglobin Globin protein 1:292 Gloss 2:168 definition 2:164 Glucocorticoid(s) adipocyte development/differentiation 2:51 definition 2:49 growth 2:75–76 pubertal growth 2:53 see also individual hormones Glucocorticoid receptors (GRs), adipocytes 2:51 Glucono-delta-lactone (GDL) 1:11, 1:298, 3:80–81 Glucosamine, as animal-derived nutraceutical 2:132–133 Glucose concentration in meat aerobic spoilage and 3:389 beef 3:389T de novo lipogenesis 2:45–47 lipoprotein lipase upregulation 2:47 photosynthesis 1:353 see also Glycolysis Glucose equivalents 1:297 Glutamate sensitivity 1:525 Glutathione 2:119 deficiency 2:119 definition 2:118 functions 2:119 in meat 2:447 reduced or oxidized forms 2:119 Glutathione peroxidase 3:399 definition 3:394 selenium in 2:126

499

Gluten 1:3 definition 1:1 use in comminuted meat products 1:293–294 Glycerin 1:301 Glycerol-3-phosphate (Gly3P) 2:47 Glycogen 1:206, 1:211, 1:242, 1:346–352 analysis 1:211 definition 2:75 formation 1:349, 1:353 macroglycogen 1:348 metabolism 1:348–349 see also Glycogenolysis in muscle cells 1:354 muscle concentrations 1:349–350 effect of preslaughter stress 1:350, 1:350F, 1:351F, 2:446 effect on meat quality 1:349–350, 1:350F, 1:351F relationship with rate of glycogen resynthesis, species differences 1:349, 1:349F resting vs. postmortem, species differences 1:242, 1:242T postmortem breakdown 1:354 proglycogen 1:348 proteins known to interact with 1:347, 1:347F structure 1:347–348, 1:347F Glycogen debranching enzyme (GDE) 1:348, 1:348–349, 1:354 definition 1:346 regulation of activity, meat tenderization and 3:436 Glycogenin 1:347, 1:347F Glycogenolysis 1:348 definition 1:346, 1:353 postmortem 1:339, 1:354 Glycogen phosphorylase (GP) 1:347, 1:348, 1:354 definition 1:346 Glycogen synthase (GS) 1:349 Glycolysis 1:353–357 anaerobic 1:348, 1:354 definition 1:346, 1:353, 1:425, 3:248 flavor, consequences for 1:356 lactate formation 1:355 meat tenderness 1:356 postmortem 1:354, 1:354F effect of postmortem glycolysis rate on water-holding capacity 1:278 shelf life, consequences for 1:356 time course 1:355–356, 1:355T, 1:356F Glycolytic potential 1:349 Glycosaminoglycans 1:242 Glyphosate 1:506 definition 1:502 GMP see Good manufacturing practices (GMPs) Gnotobiotic, definition 2:389 Goads see Electric prods (goads) Goan vindaloo 1:540–541 definition 1:538 Goat(s) 3:374–379 anemia, parasite-associated 2:475, 2:476F biological types see Goat breeds

500

Index

Goat(s) (continued) bovine spongiform encephalopathy 2:364 carcass anatomy 1:150F carcass chilling 3:313 carcass composition 3:376 chemical profile of goat meat 3:376 see also Carcass composition carcass composition, factors affecting 3:375 breeds and genetics 3:376 management 3:376 carcass quality 3:376–377 factors affecting meat flavor 3:376–377 carcass quality, factors affecting 3:375 breeds and genetics 3:377 management 3:377–378 postslaughter management 3:378 domestication 3:359, 3:374 eyelid (lower), normal color of membrane tissue 2:475, 2:476F feeding, general aspects 2:478–479 growth, factors affecting 3:375 breeds and genetics 3:375 management 3:375–376 gums, color 2:475, 2:476F hide by-products 1:113T removal 1:113 importation, cautions 2:476 internal parasites 2:475 associated anemia, diagnosis 2:475, 2:476F see also FAMACHA management/control 2:475–476 listeriosis 2:351 male, urinary calculi 2:476–477 mitochondrial DNA 3:359 numbers/geographical distribution 2:212T, 2:213T, 2:214, 3:309 scrapie 2:362, 2:364–365, 2:476 slaughter see Sheep and goats, slaughterline operation survival in harsh conditions 3:359 vocalization 3:85 world inventory 3:374–375 see also Ruminants Goat breeds 3:375 domestication 3:359, 3:374 effects on carcass composition 3:376 effects on carcass quality 3:377 effects on growth 3:375 Goat meat 2:475 chemical profile 3:376 indigenous production 2:215T Goat production 2:475–477 internal parasite management/control 2:475–476 nutritional management 2:475 systems 2:190–191, 2:194–195, 2:214–215 pastoral 2:215 see also Goat(s) Goetta 3:246 Gogigui grilling method, Korean cuisine 1:545F, 1:546 Good Hygienic Practice (GHP) 3:231 definition 3:226

Good manufacturing practices (GMPs) 2:92, 2:92–94 adjuncts to 2:94–95 basic information and documentation 2:93–94, 2:93F definition 2:92 fundamental requirements 2:94 cleaning and sanitation plan 2:94, 2:94F manufacturing conditions 2:94 see also Current Good Manufacturing Practices Good Production Practices, definition 3:168 Goose farming 2:192 see also Geese Goose meat nutrient composition 3:371T, 3:372 production, trends 3:372 Gopchang gui (Korean dish) 1:548 Goshtaba 1:539 Go¨ttinger Feldkieker, definition 1:530 Go¨ttinger Stracke, definition 1:530 GR 3:313 definition 3:309 Grain feeding, cattle fatness 3:332 Grain-finished cattle, dressing percentage 3:332–333 Gram-negative bacteria definition 3:388 irradiation effects 2:143 Gram-positive bacteria 3:388 antibiotic growth promotants effects 2:173 definition 2:289 irradiation effects 2:143 Gram stains, Bacillus cereus 2:324, 2:324F Grandin, Temple, impact of work on animal behavior during handling/ transport 3:87–88, 3:88T Grasscutters (cane rats) 2:196 Grass-finished cattle, dressing percentage 3:332–333 Gravimetric analysis 1:174 Gravimetric method moisture content measurement 3:53 water-holding capacity measurement 2:165, 2:165F Gray (Gy), definition 2:140, 2:141 Grease, commodity trading standards 1:130T Greenhouse effect 1:71 definition 1:71 Greenhouse gases 1:71, 1:502 manure and 2:156 see also Biomethane production and cleanup; Environmental impact, meat production Greenshell mussel 3:384 GreuXener salami 1:533–534 definition 1:530 production process 1:533–534, 1:533F Grilled meat-based dishes Japanese 1:544, 1:544F Korean see under Korea Grilling belt 1:374 clamshell 1:374 warmed-over flavor 1:413

Grinders definition 3:126 see also Mincers/grinders Ground beef see Minced beef Ground beef patties (hamburger) 1:556 Ground spices 1:304–305 Group breeding schemes 1:24–25 Growth 2:56 allometry 2:56–57, 2:70–71 see also Allometric growth bone see Bone growth centripetal 2:57–58 double-muscled animals 1:467–468 embryonic see Embryonic growth endocrinology see Endocrinology monitoring 2:56 physiology see Growth physiology small ruminants, factors affecting see Small ruminants see also individual tissue types Growth curves 2:56, 2:56F see also Growth patterns Growth hormone (GH) see Somatotropin (ST) Growth hormone-releasing factor (GRF) see Growth hormone-releasing hormone (GHRH) Growth hormone-releasing hormone (GHRH) definition 2:181 lean growth stimulation 2:52 placental, fetal growth 2:51 postnatal growth 2:52 production 2:181 Growth patterns 2:56–61 bone growth 2:57–58, 2:57F carcass growth 2:57, 2:58F fat depot deposition see Fat, deposition patterns gender differences 2:59–60 genetic variation 2:60 measurement 2:56–57 muscle see Muscle growth, patterns nutrition effects 2:60 organ and tissue, relative order 2:57, 2:57F Growth physiology 2:75–81 adipose tissue 2:79 age effects 2:76 bone 2:80 concepts 2:75–76 gender effects 2:76 genetic effects 2:76 metabolic effects 2:76–77 Growth promotants 1:217, 3:66–67 antibiotic see Antibiotic growth promotants (AGPs) detrimental effects in humans 3:66 metabolic modifiers see Metabolic modifiers residue analysis see Veterinary drug residue analysis Guanaco (Lama guanicoe) 2:193, 3:354 Guaranteed tenderness 3:271

Index

Guided microwave spectrometry 1:185, 2:494 definition 1:180 Guide wheels, patenting 3:48 Guinea fowl, production systems 2:192 Guinea pig 2:196 Gums definition 1:1, 1:5 as meat extenders 1:5 Gut fill, cattle dressing percentage 3:332–333

H HACCP see Hazard analysis and critical control point (HACCP) Hafnia, vacuum packaging 3:31 Haggis 1:110 Hair, contamination with 2:22, 2:22T Hair and feather meal (HFM, feather meal) 1:135 Hair meal 1:135 Hair sheep 3:375, 3:376, 3:377 Halal, definition 3:209 Halal slaughter 3:210–211, 3:282 basic procedures 3:211 definition 1:561, 3:280, 3:309 knives 1:561 poultry 3:305 sheep and goats 3:310 theological basis 3:211 Halbersta¨dter Wu¨rschten 1:534 definition 1:530 Haleem 1:540 definition 1:538 Half-cooling time 2:439 definition 2:436 Halothane 1:340 sensitivity, pigs 1:340–341 postmortem muscle pH changes 1:340–341, 1:341F Halothane gene (HAL) breeding strategies 1:341 definition 1:339 mutations 1:340–341 Ham(s) 1:447 boneless premium 1:447 section/chopped and formed hams 1:447–448, 1:448T Chinese 1:522, 1:523F, 1:524T, 1:525 cooked see Cooked ham dry-cured see Dry-cured ham(s) production, patenting 3:47 raw, nitrosamines 3:224 semiboneless 1:447 smoked, Polish 1:558 traditional bone-in see Bone-in hams Hamburger 1:556 freezing method effects 2:227 Hammond, Sir John 2:56–57 Ham production cooked hams see Cooked ham production dry-cured hams see Dry-cured ham production

Hampshire effect 3:365–366 Hampshire-type meat see Acid meat Hand-boned meat, mechanically recovered meat vs. beef and pork 2:273, 2:273T poultry meat 2:272, 2:273T Hanging, leather drying 1:122 Hanwoo beef grilling 1:545–546, 1:545F yukhoe 1:548–549, 1:548F Haptens 2:348 Hardening, meat 1:408 Hares 3:352–353 as intermediate hosts for parasites 3:40 Harmonization 2:231 definition 2:231 Harvest, definition 3:267, 3:309 Hawawshy bread 1:554 definition 1:553 Hazard definition 2:218, 3:226 risk vs. 3:227 Hazard analysis definition 3:295 risk analysis vs. 3:227 Hazard analysis and critical control point (HACCP) 2:92, 2:95, 3:232, 3:295 approach to implementation 2:95, 2:95T beef safety and quality and 3:173, 3:174–176, 3:176, 3:176T company requirements 2:95 definition 2:92, 2:301, 2:367, 3:64, 3:168, 3:173, 3:226, 3:295 Fish Welfare Assurance System and 3:425 hazard analysis 2:95 example (Vienna sausage production) 2:95, 2:96T indicator organisms and 2:304 product and process description 2:95 risk management 2:95–97 critical control points 2:95 example (Vienna sausage production) 2:96, 2:96T Hazard characterization 3:228 definition 3:216 see also Risk assessment Hazard identification 3:227 definition 1:27, 3:216 excluded pathogenic agents 1:28 imported commodities 1:28 see also Risk assessment Hazard mitigation, meatborne hazards see Meatborne hazards, mitigation Head gate, definition 3:418 Head-holders, design 3:91 Head processing, sheep and goats 3:311–312 Head removal cattle slaughter process 3:287 pig slaughter process 3:301 poultry slaughter process 3:307 Head tag, cattle 3:287 Health (human) vegetarianism and 2:135–136, 2:136–137 see also Nutrition (human) Health-enhancing components, nonmeat proteins 1:291

501

Health hazards associated with smoking of foods see under Smoking, traditional chemical see Chemical hazards, meatassociated Heart, as edible by-product 1:105–107 Heat application, water-holding capacity measurement 2:167 Heat capacity definition 1:137, 1:471, 3:460 fat composition effects 3:462–463 meat components 3:462, 3:462T Heat denaturation, meat proteins 1:404 connective tissue proteins 1:405 myofibrillar proteins 1:404 sarcoplasmic proteins 1:404 susceptibility 1:404 see also Meat protein(s), effects of heating Heated coils, ovens 3:137 Heat infiltration, local distribution vehicles 2:239–240 Heating chicken meat production systems 2:207 effects meat flavor see Flavor development, heat-induced meat flavor; Maillard reaction meat proteins see Meat protein(s), effects of heating methods, thawing see Thawing as predrying treatment 1:474 process, in meat 1:371, 1:372F Heating systems cooking processes 3:137 see also Cooking equipment see also Thermal processing Heat loads, meat product chilling/freezing, process models 2:436, 2:440–441 Heat processing see Thermal processing Heat-sealable film bags, frozen meat packaging 3:32 Heat shortening 3:269 see also Rigor shortening Heat transfer during canning see under Canning during drying of solid foods 1:473, 1:473F fundamentals 3:196–197 Heat transfer coefficient definition 1:385, 2:225, 2:236, 3:184, 3:196, 3:202 effect on thawing time 3:203 fluid velocity correlation 3:180 typical, in cooking operations 1:386, 1:387F Heat treatment see Thermal processing Heavy-duty alkaline cleaners 1:513 Heme definition 1:410 lipid oxidation 1:411 Heme group, myoglobin 1:244, 1:244F, 1:245F Heme iron see Iron, heme Hemochrome, denatured globin 1:248–249, 1:249T Hemolysin Aeromonas virulence factor 2:318

502

Index

Hemolysin (continued) definition 2:317 Listeria monocytogenes virulence factor 2:352 Hemolysis a-hemolysis, definition 2:340 b-hemolysis Aeromonas isolates 2:318 definition 2:317 Hemolytic uremic syndrome (HUS) 2:19, 2:358 Aeromonas-associated 2:320 complications 2:358 definition 2:17, 2:317 gastroenteritis signs/symptoms 2:358 Hemorrhagic colitis 2:358 Hemorrhaging in muscles, electrical stunning and 3:410, 3:410F Hepatitis E virus 2:389–390 disease 2:390 survival in food 2:390–391 virus characteristics 2:389–390 zoonotic transmission 2:390 Hepatobiliary, definition 2:317 Herbs 1:9 Bacillus cereus contamination 2:328 definition 1:304 warmed-over flavor prevention 1:413 Hereford cattle 3:329, 3:329F Heritability carcass composition traits across species 1:19T, 1:21 meat quality traits across species 1:20T, 1:21 Herring 3:337–339T nutritional content 3:336–342, 3:342T Heterocyclic amines 3:224 definition 2:100, 3:221 in processed meat 2:101 Heterocyclic aromatic amines formation during cooking, muscle fiber types 2:447 smoked foods 3:324 Heterocyclic compounds definition 1:391 polysulfur heterocyclics, formation via Maillard reaction 1:397, 1:398F Heterogeneous, definition 2:405 Heterosis 1:20–21 cattle 3:331 definition 1:19, 3:328 inbreeding depression 3:328 Heterozygous animals, definition 1:465 Hexanal lipid oxidation monitoring 1:411 warmed-over flavor indicator 1:412 Heyns nonvolatile compounds, cooked meat flavor 1:259 Hide(s) 1:112 bating 1:119–120 by-products 1:113T classification 1:112, 1:117T composition 1:112–113, 1:118T curing 1:115–116, 1:119T, 1:120T, 1:121T nonsalt methods 1:116 degreasing 1:119 dehairing see Dehairing

deliming 1:119 fleshing 1:116 grading 1:116 harvesting 1:113–115 ‘in the blue’ 1:120 moisture levels 1:116–117 pickling 1:120 quality of care 1:116–117 removal, cattle slaughter process see Cattle slaughter process retanning 1:121 safety salt use 1:116 shaving 1:121 soaking 1:117 sorting 1:116 splitting 1:118T, 1:121 tanning see Tanning thickness 1:121 trade in 1:112, 1:116T trimming 1:116 wringing/setting 1:121 yield as percentage of live weight 1:112, 1:112T yield weights 1:112T see also Leather Hide processor 1:115–116 Hide-puller technique 1:113 High hydrostatic pressure 1:301 High-oxygen packaging 3:10 definition 3:9 see also Modified atmosphere packaging (MAP) High-pathogenicity island (HPI), Yersinia enterocolitica 2:407 High performance liquid chromatography (HPLC), meat species determination 2:266 High-pressure food preservation 3:82 definition 3:78 patenting 3:47 High-pressure freezing 3:188 High-pressure pasteurization 1:301 High-pressure processing effect on water-holding capacity 1:279–280 processed meat see Processed meat, decontamination High residual feed intake (HRFI), low residual feed intake vs., methane production in ruminants 1:72–73 High-speed centrifugation, water-holding capacity measurement 2:166 Hind (doe), definition 2:190 Hindquarter pistola cut, definition 1:33 Histamine determination by paper electrophoresis (fish safety assessment) 2:14, 2:14F in raw fermented sausages 3:222, 3:222T toxicological effects 2:13, 3:222T see also Scombroid poisoning Histamine-forming bacteria (HFB), detection and counting (fish assessment) 2:14, 2:15F Histidyl dipeptides, as meat-based bioactive compounds 2:34, 2:34F

Histochemistry, postnatal muscle development 2:72–73 Histomonas meleagridis 3:40 Hock cutters/cutting, cattle hock removal 3:286 automated 1:47 Hofer Rindfleischwurst, definition 1:530 Hog casings, sausages 3:235–236, 3:236F Holding pen see Lairage/lairaging Holistic by DMRITM, definition 3:272, 3:274 Holocene, definition 3:357 Holsteiner Katenschinken, definition 1:530 Holstein-Friesian cattle 3:330, 3:330F Homeostasis definition 2:345 hurdle technology effects 2:345 Homes handling of chilled/frozen meat 2:229 thermotolerant Campylobacter control 2:387 Homocysteine, reduction, vitamin B6/B12 roles 2:127 Homogenization, sample 1:173 Homozygous animals, definition 1:465 Hong Kong antibiotic growth promotant policy 2:175T wet markets 2:244, 2:244F, 2:245F market forces 2:245 modern 2:246, 2:247F public health hazards 2:246 Hoofed animals (ungulates) African see African ungulates definition 2:190, 3:345 Horizontal gene transfer, definition 2:294 Horizontal paddle massagers 3:143, 3:143F Hormone(s) approval in USA 2:109 autocrine actions 2:49 half-life 2:75–76 paracrine actions 2:49 see also individual hormones Hormone response elements (HREs) 2:64 Hormone sensitive lipase (HSL) 2:47 Horns, dressing percentage 3:332–333 Horrat value 1:195 Horse(s) as intermediate hosts for parasites 3:40 listeriosis 2:351 slaughter process 3:291–292 Horse meat 2:197, 2:265, 3:291–292 hot boning 1:456 Horse meat scandal (2012) 2:265 Host-adapted, definition 2:367 Host colonization, Listeria monocytogenes 2:352 Hot air ovens 1:386 see also Convection ovens; Cooking equipment Hot boning 1:142–144, 1:453–457, 3:269–270, 3:448 beef 1:455 cold boning vs. 1:453, 1:457 definition 1:142, 1:329, 1:486, 3:261 electrical stimulation and 1:492–493

Index

horse 1:456 hot and warm boning operations 1:455 lamb 1:455 meat aging and 1:333, 1:335 microbiology of hot-boned meat 1:453–454 modified 1:144 pork 1:455–456 poultry 1:456–457 quality of hot-boned meat 1:454–455 true hot boning 1:453 warm boning 1:453 Hot boxes beef carcass chilling 3:289 walking beams 3:289 Hot dogs 3:243–245, 3:259–260 Hot extrusion see Extrusion cooking Hot fat, frying in 1:388 Hot-iron branding, animal welfare 3:103 Hot smoking 3:321 definition 3:321 see also Smoking, traditional Hot spot, definition 3:202 Hot toughening 3:269 Hot water carcass treatment 2:276–277 definition 2:276 pigs 3:301 surface decontamination 1:389 Hot water cookers 3:134 Hot water cooking 1:387–388 Hot wings 1:557 Hounsfield units 2:24, 2:24T Housing animal welfare see Animal welfare intensive chicken meat production systems 2:204, 2:205–206, 2:205F Howard mold-counting chamber 2:397 Human–animal relationship 3:108 evolution of philosophical thinking about human–animal bond 3:108 Human infections Aeromonas 2:318–320, 2:319T Listeria monocytogenes see Listeriosis norovirus 2:391 Salmonella see Salmonellosis sapovirus 2:391 see also Foodborne pathogens Human intestinal microflora effects of veterinary drug residues 3:65 see also Commensal bacteria Human nitrogen cycle 1:438–440, 1:439F Human nutrition/diet, meat in 2:118–123 see also Nutrition Human physiology, nitrite and nitrate 1:436, 1:437 Human transmissible spongiform encephalopathies see Transmissible spongiform encephalopathies (TSEs) Humectants 1:301 definition 1:515 Humidity absolute see Absolute humidity decreasing, chilling of meat 2:226 definition 3:50–51

effect on solid food drying 1:474 relative see Relative humidity Humidity measurement 3:50–51 calibration of hygrometers 3:52–53 selection of hygrometers 3:52 types of instruments 3:51 capacitance and resistance hygrometers 3:51 chilled mirror dew point meters 3:51 direct dielectric measurement 3:51–52 psychrometers (wet and dry bulb thermometers) 3:51 salt dew cells 3:51 use of hygrometers 3:52 Humidity ratio, definition 3:50 Hunchback, embryonic growth 2:50 Hungary, national meat research institution 2:255–256T Hunter Lab systems, meat color measurement 2:169 Hunter (Mysliwska) sausage 1:558–559, 1:559 Hurdle approach definition 2:280 processed meats 2:280–281, 2:284, 2:291 Hurdle effect 2:345 Hurdle technology 2:345–347, 3:82 aspects of 2:345–346 autosterilization 2:345 beef carcasses 3:289 carcass contamination decreases 2:346 Clostridium botulinum control in meats 2:334 definition 2:345, 3:78 design 2:347 efficacy 2:345 food quality 2:346 meat industry applications 2:346–347 modified atmosphere packaging and 2:346–347 nonthermal interventions and 2:346 traditional Chinese meat products and 1:525–526 vacuum packaging and 2:346–347 Husbandry practices, beef quality assurance (BQA) guidelines 3:174, 3:175T Huxley, Julian 2:56–57 Hybrid breeding, cattle 3:330–331 Hybrid vigor see Heterosis Hydration 1:471 Hydroallantois, cloned pregnancies 1:88 Hydrocarbons, as refrigerants 3:200 Hydrochlorofluorocarbons (HCFCs) 3:199 Hydrocolloids definition 1:1 as meat extenders 1:5 Hydrodynamic pressure, meat tenderization 3:448–449, 3:449F Hydrodyne process 3:448–449, 3:449F Hydrofluorocarbons (HFCs) 3:199 Hydrogen ions formation 1:262 see also pH Hydrogen peroxide, production by lactic acid bacteria 1:77

503

Hydrolysis amino acid analysis 1:210 sample pretreatment 1:173 Hydrolyzed plant protein (HPP) 1:300 Hydrophobic, definition 1:64 Hydrophobic grid membrane filtration (HGMF) Brochothrix thermosphacta enumeration 2:308T, 2:309 Enterobacteriaceae 2:309 lactic acid bacteria enumeration 2:308T, 2:309 meatborne pathogens 2:311, 2:315T pseudomonad enumeration 2:308, 2:308T spoilage bacteria 2:307 media used 2:307, 2:308T total psychrotroph counts 2:308, 2:308T Hydrostatic pressure, meat tenderization 3:449–450, 3:450F 25-Hydroxycholecalciferol 2:126–127 Hydroxylysine 1:321 Hygiene definition 2:204 waste management and 2:161–162 Hygiene measures 2:430 campylobacteriosis prevention 2:387 Hygienic design, processing equipment 1:511–512, 1:512F Hygrometers calibration 3:52–53 capacitance and resistance hygrometers 3:51 selection 3:52 use air humidity measurement 3:52 water activity measurement 3:52, 3:52F Hypercapnea, definition 3:401 Hypercholesterolemic, definition 2:135 Hypermuscularity genetics 1:466 see also Double muscling Hyperperoxides, warmed-over flavor 1:411 Hyperplasia definition 2:70 myofibers see Muscle fibers, hyperplasia Hyperspectral imaging definition 2:480, 2:489 meat composition measurement 2:484 Hyperspectral vision definition 2:22 foreign body detection 2:31 Hypertension 2:106 cardiovascular disease and 2:106 Hypertrophy definition 2:70 myofibers hyperplasia vs. 2:71F, 2:72 see also Muscle hypertrophy Hyperventilation, definition 3:401 Hypophysectomy, definition 2:75 Hypothalamic–pituitary–adrenal (HPA) axis definition 3:102 stress assessment 3:106

504

Index

Hypoxanthine definition 1:353 flavor 1:356 Hypoxia, definition 3:401

I Iberian ham 1:448, 1:449T, 1:550, 1:550F, 1:551F definition 2:87 effect of quality of raw material 2:87–88 salting 2:89 drying-maturation and cellar phase 2:90 resting period 2:90 see also Dry-cured ham production IBMX (3-isobutyl-1-methylxanthine), adipocyte differentiation 2:45 Ice crystal formation 3:461 extracellular, definition 3:202 as ingredient 1:299 use in curing 1:443 Ice box off-flavor 1:410 Ice point, definition 3:57 Ice slurry 3:201 Illex illecegrosus 3:386 Illicit substances definition 3:214, 3:219 testing for 3:218, 3:219 use of 3:218 Illness behavior 3:106 Immersion chilling 2:226 poultry carcasses 3:185, 3:186F rates 2:226 Immersion curing 1:421, 1:421T belly bacon 1:56 Immersion thawing 3:206, 3:206F Immobilization 3:418–420 definition 3:418 electrical 3:420 emerging economies 3:419 fish 3:419 postslaughter considerations 3:419–420 restraint vs. 3:418 Western world 3:418–419 see also Stunning Immobilized water 1:274, 1:363 Immunoaffinity cartridges (IACs), veterinary drug residue extraction 1:218 Immunoassay, definition 2:285 Immunocastration (immunoneutralization), boar taint control 1:101, 1:101T Immunocompromised individuals Aeromonas infection 2:319 listeriosis 2:351 Immunomagnetic separation (IMS) Escherichia coli O157:H7 2:311 meatborne pathogens 2:310 pathogenic Escherichia coli 2:359–360 Immunosuppression definition 3:108 stress-induced, definition 3:102 Impala (Aepyceros melampus) meat 3:349, 3:352T

Impedance see Electrical impedance Impinge, definition 3:131 Impingement chilling/freezing 3:187 Impingement oven 3:134F, 3:135, 3:135T see also Cooking processes Implicit association, definition 2:135 Import risk analysis see Animal health import risk analysis ImprovacTM, boar taint control 1:101, 1:101T Inanition, definition 2:190 Inbreeding cattle 3:328 definition 3:328 Inbreeding depression, cattle 3:328 Incineration, animal by-products 1:126 Indels, definition 2:294 India, cattle production systems 2:211, 2:213–214 Indian subcontinent, meat products 1:538–542 biryani see Biryani commercial production, future perspectives 1:542 dry salted meat see Dry salted meats Goan vindaloo see Goan vindaloo haleem see Haleem kabab see Kabab kargyong see Kargyong keema see Keema khicheri see Khicheri Kohlapuri mutton see Kohlapuri mutton meat pickles see Meat pickles momo/dumpling see Momo/dumpling pish pash see Pish pash rapka see Rapka tandoori see Tandoori tikka see Tikka wazwan meats see Kashmiri wazwan meats Indicator organisms 2:301–305 common uses 2:302–303 adequacy of processes to destroy pathogens 2:303–304 identification of contaminated raw materials 2:286, 2:302–303 identification of recontamination of processed products 2:304 definition 2:301 enumeration of indicator bacteria 2:308 hazard analysis and critical control point (HACCP) and 2:304 historical perspective 2:301 objectives 2:301–302 qualities of good indicator organisms 2:302 regulatory issues 2:304 relationships between 2:302F Indicator tests, pathogen contamination in meat 2:286 Indirect genetic markers 1:13, 1:14F Individual muscle (IM) 1:458–459 Inedible meat by-products 1:125–136 historical aspects 1:125 live animal weight 1:126 processing 1:126–127 rendering see Rendering

types 1:126 see also Animal by-products (ABPs) Infant botulism 2:330 Infectious disease(s) control see Infectious disease control eradication programs see Infectious disease eradication programs pigs 2:186 intensive production systems 2:186 reduction methods 2:186 see also specific infectious diseases Infectious disease control definition 2:186 pigs 2:186 advantages/disadvantages 2:189 antibiotic treatment programs 2:186–187 Infectious disease eradication programs, pigs 2:186, 2:187 advantages/disadvantages 2:189 at the herd level 2:187 national programs 2:187 remaining breeding stock 2:187 success rates 2:187 total depopulation 2:187 Information, patents as source 3:44 Infrared heating, processed meat decontamination 2:281 Infrared thermometers 3:59–60 Infusion, vascular, meat tenderization 3:433–436, 3:436F Ingredients 1:296–301 functional see Functional ingredients, meat products see also individual ingredients Injectable animal health products, beef quality assurance (BQA) guidelines 3:174, 3:175T Injection, chemical tenderizing mechanisms acids 3:433, 3:436T metal ions, ionic strength and 3:432–433, 3:432F, 3:434–435T see also Calcium-activated tenderization Injection point damage, carcasses 3:65F Injurious behavior, animal welfare 3:105, 3:105T In-line, definition 2:480, 2:489 In-line methods, performance 2:480–481, 2:481F In-line mincer/grinder 3:129 Innards, French dishes 1:528 Innate behavior definition 3:102 see also Animal behavior Inorganic matter, in meat see Minerals Inosine, definition 1:353 Inosine monophosphate (IMP) 1:356 definition 1:353 In-package thermal pasteurization, processed meat 2:281, 2:291 Insecticides definition 2:204 see also Pesticides Insensible, definition 3:421 Institute of Food Technology (IFT) 3:148T

Index

Institutional Meat Purchase Specifications (IMPS) program 1:459, 2:232 definition 2:231 see also Meat marketing, requirements/ specification Insulation definition 3:196 intensive chicken meat production systems 2:206 local delivery vans 2:239, 2:240F Insulin adipocyte differentiation 2:45 adipogenesis 2:51 carcass fatness 2:52–53 fatty acid uptake 2:80 lipogenesis 2:51 lipolysis 2:47 lipoprotein lipase upregulation 2:47 postnatal growth 2:52–53 secretion, estrogenic steroids effects 2:78 skeletal muscle growth 2:79 Insulin deficiency, poor postnatal growth 2:52–53 Insulin-like growth factor(s) (IGFs) muscle development role 2:74 muscle growth 2:78 myogenesis 2:50 Insulin-like growth factor bind proteins (IGFBPs), muscle growth 2:78 Insulin-like growth factor I (IGF-I) beta-adrenergic agonist effects 2:67 embryonic growth 2:49–50 muscle development 2:50, 2:77 muscle growth 2:78 postnatal growth 2:52 Insulin-like growth factor II (IGF-II), muscle development 2:50 Insulin-like growth factor II (IGF-II) gene, imprinting 2:49–50 Insulin resistance, somatotropin 2:183 Insurance theory, meat tenderness 1:253 Integrins, calpain and 1:281 Intelligent packaging 3:9 see also Controlled atmosphere packaging (CAP) Intensive production/farming cattle, extensive systems combined with 2:212, 2:213F chicken meat production see Chicken meat production systems definition 2:190 pig production see under Pork production Interfacial protein film (IPF) 1:284 definition 1:283 formation, emulsion/batter stability and 1:285–286 Interferences, definition 1:193, 1:194 Interlaboratory study, definition 1:217 Intermediate methods, pig carcass classification 1:318 Intermediate moisture food (IMF) 1:472 biltong as 1:516 Intermuscular fat 1:20, 1:223, 1:223F definition 1:19, 2:56 deposition patterns 2:59 gender differences 2:60

distribution 1:159–160, 1:164F see also Adipose tissue Internal business regulation, meat business 1:484 Internal heating methods, thawing 3:207 Internal parasites, goats see Goat(s) Internal Standard (IS), definition 1:217 International Association for Food Protection (IAFP) 3:148T International Butchers Confederation (IBC) 3:148T International Congress of Meat Science and Technology (ICoMST) 3:147F, 3:148T International Featured Standard (IFS) 3:164 International Federation for Organic Agricultural Movement (IFOAM) 2:199 International Meat Secretariat (IMS) 3:148T International Natural Sausage Casing Association (INSCA) 3:148T International Organization for Standardization (ISO) 1:193 chemical standards and official methods on meat and meat products 1:197 containers for sea transport of meat 2:237 definition 3:272 see also entries beginning ISO International trade policy 1:483–484 Intestinal microflora human, effects of veterinary drug residues 3:65 see also Commensal bacteria Intestinal mucosal cells, stearoyl-coenzyme A desaturase (SCD) activity 1:230, 1:230F Intestines as edible by-products 1:110 beef intestines 1:110, 3:237, 3:237F pig intestines 1:110, 3:235–236, 3:236F somatotropin effects 2:77T Intrafascicularly terminating myofibers 2:73 definition 2:70 Intramuscular fat 1:20, 1:152, 1:223–224, 1:223, 1:223F concentration, as intrinsic determinant of meat tenderness 3:453T tenderness measurement and 3:453T, 3:458 contribution to cholesterol concentration in meat 1:230–231 definition 1:19, 1:307, 2:56, 2:181 deposition patterns 2:59 distribution in pigs in carcasses 1:152, 1:154F in individual muscles 1:152, 1:155F distribution of marbling adipocytes 1:230, 1:231F fatty acid composition 1:224–226, 1:226F, 1:227F see also Adipose tissue; Carcass fat; Fat; Marbling Intrinsic determinant, definition 3:452 Intrinsic factors definition 2:280, 2:345 in preservation 2:345

505

Intrinsic foreign bodies, in meat definition and implications 2:22, 2:22T see also Foreign bodies Intrinsic resistance, definition 2:412 Inulin definition 1:1 as meat extender 1:4–5 Inverted dressing definition 3:309 lamb carcasses 1:48–49 in vitro meat 2:234–235, 2:235 definition 2:231 Iodine value 1:240–241, 3:367 definition 3:363 Ionic strength effect on protein solubility 1:269, 1:269F effect on water-holding capacity 1:279, 1:279T, 1:280T muscle, postmortem changes 3:432, 3:432F effects of injection of metal ions 3:432–433, 3:434–435T Ionizing radiation 1:301, 2:140–141 cellular effects 2:140–141 definition 2:140 Ionomers, packaging film chemistry 3:21 Ionophore, definition 2:172 Ionophore antibiotics 2:174–175 as antibiotic growth promotant substitutes 2:175 coccidial resistance 2:175 coccidiosis prevention 2:174 necrotic enteritis 2:175 Ion pump, definition 1:358 Ion-selective field-effect transistor (ISFET) technology, pH measurement 2:493 Ireland, meat research institutions national 2:255–256T provincial 2:257–261T Irish Statutory Instrument, beef carcass classification/grading carcass categories 1:309T conformation 1:308T fat cover 1:309T machine classification 1:308–309 Irish Universities Nutrition Alliance (IUNA) 2:124 Iron 2:124–125 absorption from meat 2:125 bioavailability 2:125 carcinogenesis role 2:121 deficiency 2:120–121, 2:124–125 vegetarians 2:138 functions 2:120–121 heme 2:125, 2:138 as animal-derived nutraceutical 2:133 catalytic effect, carcinogenesis and 2:122–123, 2:122F cooking effect on 2:125 definition 2:124 in human diet 2:120–121 importance of meat 2:125 meat content 2:124–125 mechanically recovered vs. hand-boned meat

506

Index

Iron (continued) poultry 2:272–273 red meat 2:273, 2:273T nonheme 2:125, 2:138 absorption promoted by meat 2:125 definition 2:124 lipid oxidation 1:411 Irradiation definition 2:140, 3:78 of food see Food irradiation see also Gamma-irradiation ISO see International Organization for Standardization (ISO) ISO 9000 series 3:160 definition 3:159 ISO 17025:1999 standard 2:146 definition 2:145 3-Isobutyl-1-methylxanthine (IBMX), adipocyte differentiation 2:45 Isoeugenol (Aqui-STM) 3:422–423 Isolated soy protein concentrate (ISP) 1:3 Isosbestic, definition 3:70 Isosbestic (isobetic), definition 2:164 Isosbestic (isobetic) points deoxymyoglobin, oxymyoglobin and metmyoglobin 3:72–73, 3:74F pigments in fresh meat 2:169–170 Isothermal detection, foodborne pathogens 2:296 Italian salami 1:551 Italian sausage products 3:261 Italian White breeds, cattle 3:329–330 Italy, provincial meat research institution 2:257–261T

J Jagdwurst 3:243 Jalowcowa sausage 1:559 Jambon de Paris 1:528–529, 1:529F Jambon sec 1:529 Japan 1:543–549 antibiotic growth promotant policy 2:175T beef carcass classification/grading 1:313 carcass price and 1:314, 1:315F cumulated records 1:314T damage indication stamps 1:314, 1:314T fat color 1:314, 1:314F, 1:314T fat luster/quality 1:314 marbling 1:312F, 1:313, 1:313T meat brightness 1:313, 1:314T meat color 1:313, 1:313F, 1:314T meat firmness/texture 1:314, 1:314T meat quality score 1:313–314 procedure 1:313 yield/meat quality score carcass stamping 1:314 yield score 1:311T, 1:312F, 1:313 beef carcass price-marbling relationship 1:314, 1:315F beef marbling, feeding systems in 1:314–315 FOSHU (foods for specified health use) 2:32–33

marbling to meat palatability relationship 1:254–256, 1:256T meat-based cuisine 1:543–544, 1:543F, 1:544F deep-fried dishes 1:544, 1:544F grilled/pan-fried dishes 1:544, 1:544F steamed dishes 1:544–545, 1:545F provincial meat research institutions 2:257–261T Japanese Black cattle Beef Marbling Standard (BMS) score 1:231–232, 1:231F propensity to fatten 3:332 Japanese Pork Consumer Survey, marbling to meat palatability relationship 1:254–256, 1:256T Japanese-style bread crumbs 3:116, 3:119 Japan Meat Grading Association, Beef Carcass Grading Standard 1:313 Jellied products 1:110 Jerky definition 1:555 restructured 1:555–556 whole-muscle 1:555 Jersey cattle 3:330 Jinhua ham 1:522, 1:523F Johne’s disease 2:342 Jokbal (Korean dish) 1:547F, 1:548 Journey definition 3:95 see also Transport Journey times 3:98 Juiciness 3:276 definition 1:252 meat fat content and 1:252–253 muscle fiber types and 2:446 muscle myofibrillar proteins and 1:257 Juniper (Jalowcowa) sausage 1:559

K Kabab 1:539–540 definition 1:538 Kabanos, production 3:326 Kabanosy 1:558, 1:559 Kangaroo hide by-products 1:113T meat 3:352 fat content 3:352 production systems 2:197 slaughter process 3:293 Karaage (Japanese dish) 1:544, 1:544F Kargyong 1:542 definition 1:538 Kashmiri wazwan meats 1:539 aab gosht 1:539 definition 1:538 nate-yakhni 1:539 rista and goshtaba 1:539 rogan josh 1:539 tabak manss 1:539 Kassler, definition 1:530 Katsu (Japanese dish) 1:543–544, 1:544, 1:544F

Kebabs 1:553 definition 1:553 Keema 1:541 definition 1:538 Kennedy gauge 3:26 Kettles, batch cooking 3:131, 3:131F Khicheri 1:541 definition 1:538 Kid hides, by-products 1:113T Kidney, as edible by-product 1:107–108 Kidney cancer 2:102 Kielbasa 3:245 Killing definition 3:421 see also Slaughter Kit/kitten, definition 2:190 Kjeldahl method 1:182T, 1:183, 1:209 Knacker, definition 1:530 Knackwurst 3:245, 3:260 Knife-skinning technique, hide removal 1:113 Knocking see Stunning Knocking box see Stun box Kobeba 1:554 Kobe beef 1:543–544, 1:543F Kohlapuri mutton 1:540 definition 1:538 Korea 1:543–549 meat-based cuisine 1:545–548 grilled/pan-fried dishes 1:546–548 bulgogi 1:546, 1:546F dak galbi 1:546F, 1:548 galbi 1:546F, 1:547 gogigui grilling method 1:545F, 1:546 makchang 1:547F, 1:548 samgyepsal gui 1:546–547, 1:546F raw dishes 1:548–549, 1:548F steamed/soup-type dishes 1:548 bossam 1:547F, 1:548 jokbal 1:547F, 1:548 samgyetang 1:548, 1:548F seollongtang 1:548, 1:548F sundae 1:547F, 1:548 South see South Korea Korokke (Japanese dish) 1:544, 1:544F Kosher 3:282 definition 1:561, 3:209, 3:280 Kosher salami 3:243 Kosher slaughtering (shechita) 3:282 basic procedures 3:210 bedika 3:210 definition 3:209 blood loss 1:562–563 definition 1:561, 3:209, 3:280 pain during 1:562 slaughter knives 1:561, 1:561F, 3:210 theological basis 3:209–210 Krakowska 1:558 Krill 3:381 Krupnioki 1:558, 1:559 Kuemmelwurst (Carawaywurst) 3:245 Kuru 2:365, 2:366F K value, measurement by paper electrophoresis (fish freshness assessment) 2:11, 2:11F, 2:12F

Index

L Lab color space 2:168, 2:169F definition 2:164 Labeling 2:107 country-of-origin see Country-of-origin labeling (COOL) mechanically recovered meat, legislation 2:271–272 naturally cured meat products see Naturally cured meat products nutritional see Nutritional labeling organic cured meat products see Organic cured meat products uncured processed meats see Uncured processed meats Labels, packages 3:19–20 Laboratory accreditation 2:145–151 accreditation and notification system 2:145–146 benefits 2:148–149 comparison between accreditation and notification systems 2:147T costs 2:148 development 2:145–146 equivalent 2:146 definition 2:145 procedure 2:147–148 accreditation/notification 2:148 application for approval of competence 2:148 auditing procedure 2:148 fields of activity of conformity assessment bodies 2:148F preparatory steps 2:148 surveillance 2:148 standards to be met 2:146–147, 2:146F, 2:147T helpful websites 2:147T laboratory requirements see Laboratory requirements prospects 2:150 Laboratory equipment, laboratory accreditation requirements 2:149 Laboratory requirements 2:149 management requirements 2:149 technical requirements 2:149 environment 2:149 equipment 2:149 personnel 2:149 reagents, culture media, and reference material 2:149–150 sampling and sample handling 2:150 testing methods and quality of performance 2:150, 2:150F Laboratory standard, definition 1:217 Laco´n 1:550 Lactate 1:346–347 anaerobic glycolysis 1:354F, 1:355 muscle concentrations, resting vs. postmortem, species differences 1:242, 1:242T Lactic acid beef carcasses, use on 3:289 carcass decontamination 2:278 meat tenderization 3:433, 3:436T

pH 1:262 see also pH, meat Lactic acid bacteria (LAB) 3:390, 3:391 antimicrobial activities 1:76–77 bacteriocins see Bacteriocins Clostridium botulinum control in meats 2:334 hurdle technology and 2:346 hydrogen peroxide production 1:77 nutrient competition 1:77 organic acid production 1:77 definition 1:76 enumeration media 2:309 as ingredients 1:300 use in meat fermentation 1:76, 2:1, 2:3 vacuum packaging 3:31 Lactobacillus processed meat preservation 2:291 Wiltshire bacon spoilage 1:61 Lactobacillus sakei, use in meat fermentation 2:3 Lactogenic, definition 2:49 Lacto–ovo vegetarians 2:135 Lactose, as sweetener in meat products 1:444 Lagomorphs, as intermediate hosts for parasites 3:40 Lagoons, anaerobic 2:154 Lag phase, microbial growth 2:431, 2:431F Lairage/lairaging 1:366, 3:98–100 animal inspection on arrival 3:99, 3:99F cattle automated 1:47 movement to stunning pen from 3:100 definition 1:366, 3:84, 3:95, 3:363 design of lairages 3:92–93 drains and washdown 3:93 flooring surface 3:92–93 layout 3:92F, 3:93 use of powered gates 3:93 lighting/illumination 3:100 movement to stunning pen 3:100 pigs 1:367, 3:297 dressing percentage and 3:365 meat quality and 1:367, 1:367T movement to stunning pen 3:100 showering 3:99–100, 3:99F water availability 3:99 welfare requirements 3:99 Lama guanicoe (guanaco) 2:193, 3:354 Lamb (meat) aging 1:335 carcasses see Lamb carcass(es) chemical profile 3:376 chop, anatomical features 1:151F cold shortening 1:343 fatty acid composition 2:116, 2:116T flavor mutton 1:260 sensory assessment 3:276–277 unacceptable 3:276–277 New Zealand, sea transport 2:236–237 sensory assessment see Sensory assessment, meat sensory properties, yeast effects 2:400

507

toughness, mechanical measurement 2:494–495 vacuum packaging 3:31 zinc source 2:126 see also Sheep meat Lamb(s) (animal) embryonic growth, morphogens 2:50 slaughter see Sheep and goats, slaughterline operation see also Sheep Lamb carcass(es) 3:179 chilling 1:146, 3:313 classification and grading 3:312–313 automation 1:52 Clostridium perfringens contamination 2:337–338 cutting 1:462 automation see Cutting and boning, automation foresaddle component 1:463 foreshoulder–brisket separation 1:463 hindsaddle component cutting 1:463 primal breaking 1:462–463 rack removal 1:463 typical breakdown (cuts) 1:38, 1:39F wholesale cuts 1:463F hot boning 1:455 inverted dressing 1:48–49 see also Sheep Lamb production ranking by country 2:215, 2:215T see also Sheep production Lameness, pigs 3:171 Laminated casings, sausages 3:237 Lamination, multilayer packaging films 3:22 Lamini group, definition 1:518 Land application, manure 2:155–156 Land use, environmental impacts 1:503 Lanthionines 1:77 Lard fatty acid composition 1:132T properties 1:130–131 uses 1:131 Large calf syndrome 2:49–50 Large lamb syndrome 2:49–50 Laser Doppler anemometers 3:55 Latent heat 3:462–463 definition 3:460 in volumetric terms 3:463 Latent heat of evaporation 3:181 Latent heat of freezing 3:462 Latent heat of fusion 3:181 Latent heat of sublimation 3:181 Layout bacon 1:57 Lead intoxication 3:67–68 Leaf fat removal 3:301 Lean beef see Beef, lean Lean finely textured beef (LFTB) 2:270, 2:271 definition 2:270 Lean meat, macronutrients in 2:111, 2:111–112 fats 2:114 Lean meat content, definition 1:316 Leather area measurement 1:123

508

Index

Leather (continued) buffing 1:122 coating materials 1:123 conditioning/wetting back 1:122 drying 1:122 dyeing/coloring 1:121–122 fatliquoring 1:122 finishing 1:122–123 physical properties 1:122T, 1:123–124 planning 1:123 setting out 1:122 shaving 1:121 splitting 1:121 staking/mechanical massaging 1:122 tanning see Tanning thickness 1:121 trade in 1:112, 1:114T, 1:115T worldwide production 1:112, 1:114T see also Hide(s) Leavened systems, coating configurations 3:117–118 Lebanon bologna 1:556 Legal requirements curing agents 1:200, 1:201T, 1:443 for patentability of inventions 3:42 Legislation animal welfare 3:103 foreign bodies in meat 2:23 mechanically recovered meat (MRM) 2:271–272 polychlorinated biphenyls and dioxins in food and animal feed 1:498–499 see also European Union (EU); Regulations/regulatory issues; specific legislations/regulations Leitsa¨tze fu¨r Fleisch und Fleischerzeugnisse des Deutschen Lebensmittelbuches, definition 1:530 Lentiviral vectors, transgenic animal production 1:93 Lentivirus, definition 1:92 Leona bologna 3:243 Leoprids 2:195 Leptin definition 2:43 function 2:44 growth 2:54 Leptin resistance, obesity 2:54 Level of interest, definition 1:217 Liaison Centre of the Meat Processing Industry in the EU (CLITRAVI) 3:148T Life cycle analysis (LCA) 3:427 definition 3:427 meat production studies 3:427 Ligamentum nuchae 1:149–150, 1:239 Ligase chain reaction (LCR), Listeria monocytogenes detection 2:350 Lighting chicken meat production systems 2:208 lairage/holding pens 3:100 Limit of detection (LOD) calculation 1:188–189 definition 1:187, 1:193, 1:194 Limit of quantitation (LOQ) 1:189–190 Lineage 2:348

Line boning, definition 1:33 Linguic- a 1:519, 1:519F, 1:520F, 3:245 Link (sausages), definition 3:241, 3:256 Linkage disequilibrium 2:41 Linoleic acid oxidation, warmed-over flavor 1:411 structure 1:229F, 2:473F a-Linolenic acid, definition 2:111 Lipase(s) action during dry curing 1:427 definition 1:425, 3:248 Lipid(s) 1:222, 1:239–241 accumulation in adipose tissue 1:224, 1:224F, 1:225F in meat 1:226–228, 1:227F, 1:228F, 2:113–115, 2:115F autoxidation 1:259–260 composition affected by animal domestication 3:361 fatty acid composition ground beef 1:222, 1:233, 1:233F lipid melting point and 1:233, 1:233F palmitoleic acid vs. stearic acid, subcutaneous adipose tissue lipids 1:232, 1:232F subcutaneous, intramuscular, and muscle lipids 1:224–226, 1:226F, 1:227F see also Fatty acid(s) in human diet 2:121–122 vegetarianism benefits 2:138 meat flavor and 1:258, 2:446 meat tenderness and 1:253 metabolism anabolic see Anabolic lipid metabolism catabolic see Catabolic lipid metabolism neutral see Triacylglycerols off-flavor development 1:259–260 oxidation see Lipid oxidation sources in meat 1:222–224, 1:223F types in meat 2:114 see also Adipose tissue; Fat; Fatty acid(s) Lipid droplets, adipocytes 2:45, 2:46F Lipid free radicals 1:411 Lipid–Maillard interactions 1:379–380 meat flavor compounds from 1:378, 1:380, 1:398–400, 1:399F, 1:400F see also Flavor(s); Flavor development Lipid melting points 1:233, 1:240T stearic acid and 1:233, 1:233F Lipid oxidation 2:116, 3:193–194 control in meat products 1:10 definition 3:191 enhancement 2:116 flavor development role in dry sausages 3:252 heat-induced meat flavor 1:379 interaction with Maillard reaction products 1:379–380 see also Lipid–Maillard interactions irradiation-induced 2:142 nutritive implications 2:116 warmed-over flavor 1:410–411 see also Lipid peroxidation Lipid oxidation aldehydes, definition 1:391

Lipid oxidation-induced myoglobin oxidation 1:248, 3:398 Lipid peroxidation 3:394–395 normal 3:395–396, 3:395F see also Lipid oxidation; Warmed-over flavor Lipid retention, pigs 2:455–456 Lipogenesis 2:79 definition 2:43 insulin role in 2:51 Lipolysis 2:46F, 2:47–48 definition 1:425, 1:550, 2:43, 2:79, 3:248 in dry curing see Dry curing flavor development role in dry sausages 3:250–251 regulation 2:47 yeasts 2:400 Lipopolysaccharides (LPS), definition 2:367 Lipoprotein lipase (LPL) 2:47 Liquid carbon dioxide, cryogenic refrigeration 3:181 Liquid chromatography (LC) 1:177 veterinary drug residue analysis 1:219–220, 1:219T Liquid chromatography–mass spectrometry (LC–MS), definition 2:324 Liquid immersion chilling 3:180–181 Liquid-in-glass (liquid-filled) thermometers 3:57 Liquid–liquid extraction 1:174 Liquid nitrogen 2:238 cryogenic refrigeration 3:181 as refrigerant 1:301 systems 2:238, 3:188–189 transport of meat/meat products 2:238, 3:188–189 Liquid smoke (smoke condensate) 3:315–320 as flavor 1:300, 3:318, 3:319 preparations chemical composition 3:316–317 definition 3:315 production methods 3:315–316 properties 3:319 antioxidative 3:319 bacteriostatic/bactericidal 3:319 use of 3:318–319 health aspects 3:319 warmed-over flavor prevention 1:414 Liquid smoke (smoke condensate) application methods 3:140, 3:141F, 3:317–318 smoke regeneration 3:317, 3:318F, 3:318T smoke chambers 3:317, 3:317F traditional smoking vs. 3:315, 3:316, 3:318 see also Smoking Lisiecka sausage 1:559 Listeria 2:19 detection/enumeration 2:311–314 direct plating 2:315T enrichment procedure 2:313–314T, 2:314 plating procedures 2:313–314T pre-enrichment procedure 2:313–314T reservoirs 2:19

Index

Listeria monocytogenes 2:19, 2:290, 2:348–356 contamination of ready-to-eat (RTE) foods see Ready-to-eat (RTE) products/foods control measures 2:354–356, 2:355T direct plating 2:315T general characteristics 2:348 morphology, culture, and metabolism 2:348–349, 2:348F taxonomy 2:348 hazard analysis and critical control point, Vienna sausage production 2:96 infection see Listeriosis isolation and identification 2:349–350 conventional methods 2:348F, 2:349–350 selective agents/media 2:349, 2:349T rapid detection methods 2:350–351 mechanism of pathogenicity 2:352 colonization of host 2:352 intracellular cycle of infection 2:352 virulence factors 2:352–353 Listeria Repair Broth 2:314 Listeriosis 2:348, 2:351 in humans 2:19, 2:348, 2:351–352 incidence 2:19, 2:354 incubation period 2:351 meatborne, epidemiology 2:19, 2:354, 2:355T in pregnancy 2:351 symptoms 2:19, 2:351 treatment 2:351–352 see also Listeriosis, meatborne in meat animals 2:351 see also Listeria monocytogenes Listeriosis, meatborne epidemiology 2:353, 2:353F contamination of meat processing environments and meats 2:353, 2:353F incidence, growth, and survival on meats 2:353–354, 2:354T listeriosis associated with meats 2:19, 2:354, 2:355T heat resistance 2:354, 2:354T preventive measures 2:354–356, 2:355T Litter, chicken meat production systems 2:208–209 Littorina littorea 3:385 Live brine definition 1:58 Wiltshire bacon production 1:58–59 Liver de novo lipogenesis 2:45–47 as edible by-product 1:104–105 somatotropin effects 2:77T stearoyl-coenzyme A desaturase (SCD) activity 1:230, 1:230F Liver abscess(es), somatotropin-treated steers 2:184 Liver sausage 3:259 German 1:531T, 1:535–536 Pfa¨lzer Leberwurst see Pfa¨lzer Leberwurst Thu¨ringer Leberwurst see Thu¨ringer Leberwurst

spices used 1:306T spreadable 3:258, 3:259 Livestock antimicrobial-resistant organism transmission see Antimicrobialresistant bacteria transmission, wildlife/environmental contributions methane production see Biomethane production and cleanup production environmental impacts see Environmental impact, meat production optimization of efficiency and sustainability 3:427–428, 3:428T see also specific livestock production systems see also specific types of livestock Llama meat 3:354, 3:355T production systems 2:193 Loading 3:96–97, 3:96F, 3:97F cattle 3:96 pigs 1:366–367, 3:96, 3:96F see also Transport Lobster 3:380 common edible species 3:382T spiny 3:380, 3:381F, 3:382T Local delivery vans, meat/meat products see Transport of meat/meat products Local delivery vehicles, for meat products see Transport of meat/meat products Locke, John 3:108 Locus of enterocyte effacement (LEE) pathogenicity island enteropathogenic E. coli 2:358 Shiga toxin-producing E. coli 2:358 Log phase, microbial growth 2:431, 2:431F Loin boning, automatic, beef carcasses 1:37 Loligo opalescens 3:386 Loligo pealei 3:386 Longaniza 1:519–520, 1:520F Long bone growth see Bone growth Longissimus muscle lipid accumulation 1:226 stearoyl-coenzyme A desaturase (SCD) activity 1:230F Low-density lipoprotein (LDL) atherogenesis and 2:105 cardiovascular disease and 2:105, 2:106 definition 2:105 oxidation 2:105 Low-fat diet 2:109 Low-fat meat batters 1:287 Low-fat meat product, patenting 3:45 Low-oxygen packaging 3:10 definition 3:9 residual oxygen effects 3:10–11 see also Modified atmosphere packaging (MAP) Low pathogenicity avian influenza (LPAI), imported poultry meat 1:29 Low-protein diet 2:109 Low residual feed intake (LRFI), high residual feed intake vs., methane production in ruminants 1:72–73

509

Low-salt meat batters 1:287 Low-speed centrifugation, water-holding capacity measurement 2:166, 2:166F Low-temperature cooking 1:372F, 1:373 L-644,969 2:68 Lubrication effect, meat tenderness 1:253 Luminescence spectrometry 1:175 Lung cancer 2:102 Lycopene, nutritional enhancement of meat products 2:452–453 Lymphoreticular system, definition 2:362 Lyonerwurst 3:245 Lysine in meat proteins 2:112, 2:118–119 requirement, pigs 2:458–459, 2:459T, 2:461, 2:461T Lysosomes, sarcoplasm 1:159

M Maasai, definition 2:211 Mackerel 3:337–339T nutritional content 3:336–342, 3:342T Macroglossia double-muscled animals 1:467 Macroglycogen 1:348 Macronutrients in meat 2:111–117 carbohydrates 2:111 content 2:111 energy and cholesterol contents 2:114T energy and cholesterol intake (by country) 2:113T fats see Fat, content (meat); Fatty acid(s); Lipid(s) intake by nutrient (by country) 2:113T meat consumption levels (by country) 2:111–112, 2:112T oxidation and 2:116 see also Lipid oxidation protein see Meat protein(s); Nutrition (human) Macrophage, definition 2:367 Mad cow disease see Bovine spongiform encephalopathy (BSE) Magnesium adenosine tripolyphosphate (Mg-ATP) cation shielding of Mg-ATP and its effect on water held between proteins 1:275, 1:276F definition 1:274 Maillard browning 1:9, 1:391, 1:400–401 chromophores involved 1:400, 1:401F see also Melanoidins definition 1:7, 1:391 reactions 1:394F, 1:400, 1:401F see also Maillard reaction Maillard reaction(s) 1:9, 1:379, 1:391–394, 1:401–402 cooked meat flavor 1:258–259 definition 1:370, 1:391, 2:1 early stages 1:392–394, 1:393F, 1:394F, 1:395F degradation of reaction intermediates to flavor compounds 1:393, 1:394F, 1:395F

510

Index

Maillard reaction(s) (continued) initiation 1:392–393, 1:393F Strecker reaction 1:394, 1:395F factors affecting 1:392 historical aspects 1:391 later stages 1:394–395 meat flavor compounds generated from 1:378, 1:392F, 1:395–396 lipid–Maillard interactions 1:378, 1:380, 1:398–400, 1:399F, 1:400F nitrogen-containing compounds 1:396 oxazoles and oxazolines 1:396 pyrazines 1:396, 1:396F oxygen-containing compounds 1:394F, 1:395F, 1:396 sulfur-containing compounds 1:396–397 from furan-like components 1:397–398, 1:398F, 1:399F polysulfur heterocyclics 1:397, 1:398F thiazoles and thiazolines 1:397, 1:397F thiophenes 1:397 sausage fermentation and 2:4–5 see also Flavor development Maillard reaction products (MRPs) 1:391 definition 1:410 see also Maillard reaction Maine-Anjou cattle 3:329–330, 3:329F Makchang (Korean dish) 1:547F, 1:548 Male hormones, pubertal growth 2:53 Male meat-producing animals, castration 1:97 Malignant hyperthermia syndrome (MHS) 1:340 Malondialdehyde assay 3:395 definition 3:394 lipid oxidation marker 1:412 Mammalian myoglobin amino acid sequences 1:244–245, 1:246F see also Myoglobin Management requirements, laboratories 2:149 Manufacturing conditions, good manufacturing practice 2:94 see also Good manufacturing practices (GMPs) Manure antimicrobial-resistant organisms and 2:418 definition 2:152 Manure management 2:152–156 air quality and 2:155–156 definition 2:152 farm nutrient balance 2:153 greenhouse gases and 2:156 land application 2:155–156 manure treatment 2:154 aerobic 2:154 anaerobic 1:73, 1:74F, 2:154 composting 2:155 to reduce methane emission/biogas production 1:73–74, 1:74F regulatory requirements 2:153

Manure nutrients 2:152–153 influence of feeds 2:153–154 monogastrics 2:153–154 ruminants 2:154 nitrogen 2:153 environmental impacts 1:503–504 phosphorus 2:153 environmental impacts 1:504 potassium 2:153 Marbling 1:152, 1:223, 1:223F application of genomic technologies 2:39 cold shortening 1:256 definition 2:37, 2:489, 3:328 growth indicator 1:256 measurement in beef 2:493–494 in pork 2:490–491 meat flavor 1:255T, 1:256–257, 1:256T meat palatability 1:253–256 consumer detection 1:254, 1:255T geographical/cultural influences 1:254–256 indicator 1:253–254 meat tenderness 1:253 indirect measure 1:256–257 nutritional status indicator 1:256 somatotropin-treated animals 2:184 steroid hormone effects 2:66 Window of Acceptability 1:252, 1:253F see also individual meats; Intramuscular fat Margarine, Benecols 2:453 Marinade definition 3:123 see also Brine injectors Marinade system, flavoring ingredients 1:305 Marination, warmed-over flavor prevention 1:415 Marker-assisted selection (MAS) 1:12–18 definition 1:12 low boar taint pigs 1:101–103, 1:102T see also DNA markers Marker panels bovine meat quality 2:38 porcine meat quality 2:39 Market forces, wet markets 2:245 Marketing cold chain see Cold chain requirements/specification see Meat marketing, requirements/ specification transport of products see Transport of meat/meat products Masmat 1:554 definition 1:553 Massage, cure application 1:446 Massagers 3:143–146 types 3:143, 3:143F Massaging 3:143 binding strength–meat temperature relationship 3:145 brine-treated meat 1:422 cooked ham production 2:84 definition 3:143 dry-cured ham production 2:88–89 emulsion formation 1:296–297

meat marination 3:145 time–work intensity relationship 3:144 see also Mechanical conditioning Mass spectrometry (MS) 1:177–178 flavor detection 1:260 high-resolution methods 1:178 MS–MS and MSn methods 1:177–178 as proteomics tool 3:155 veterinary drug residue analysis 1:219, 1:219T Mass transfer during canning see under Canning during drying of solid foods 1:473, 1:473F Matrix-assisted laser desorption/ionization (MALDI) definition 2:1 sausage ripening studies 2:4 Matrix solid-phase dispersion 1:174 veterinary drug residue extraction 1:218 Maximum permissible level, definition 3:214 Maximum residue level (MRL) 1:217, 3:218 definition 3:64, 3:214 Mbar, definition 3:26 Meal extract 1:109 Measurement errors, temperature see Temperature measurements, error sources Meat additives see Additives (meat/meat products) adulteration 2:265 aging see Aging, meat appearance see Appearance, meat bacteriocin application see Bacteriocins basic tastes 1:259 batter see Batters, meat chemical and physical characteristics 1:235–243 pH, measurement see pH, measurement, meat protein functionality see Muscle proteins, functionality resistance to heat processing and 1:138 see also Meat components chemical hazards associated with see Chemical hazards, meat-associated color see Meat color components see Meat components consumption see Consumption (meat) content, calculation 1:170 cooked see Cooked meat(s) for curing 1:443 see also Cured meats dark, firm, and dry see Dark, firm, and dry (DFD) meat definition 3:216 dioxin/polychlorinated biphenyl concentrations 1:499 emulsions see Meat emulsion(s) enhancement see Meat enhancement flavor see Flavor frozen see Frozen meat as functional food see Functional food(s)

Index

hierarchy among semivegetarians 3:280, 3:280T juiciness see Juiciness macronutrients in see Macronutrients in meat mechanically recovered see Mechanically recovered meat (MRM) mechanically separated see Mechanically separated meat (MSM) microbial contamination see Fresh meat, microbial contamination microstructure effects of heating see under Meat protein(s) near infrared spectroscopy and 3:72, 3:72F, 3:73F, 3:74F minced see Minced meats nutritional enhancement 2:452–453, 2:453T palatability see Meat palatability as pathogen-introducing vehicle 1:29 pH see pH, meat pigments see Pigments prices see Meat pricing systems processing see Processing production see Meat production products see Meat products proteins see Meat protein(s) quality see Meat quality reduced consumption reasons for 3:282, 3:282T see also Vegetarianism research institutions see Meat research institutions sensory assessment see Sensory assessment, meat tenderness see Tenderness texture see Texture toughness see Meat toughness transportation see Transport of meat/meat products wholesale cuts, terminology 1:458–459 see also Fresh meat; individual meats; Muscle Meat analogs, extrusion technology 1:568 Meat and bone meal (MBM) 1:134 bans on use 1:134 cattle feed, bovine spongiform encephalopathy outbreak and 2:363 definition 1:134 protein content 1:134, 1:135T unidentified growth factors 1:130 Meat and Livestock Australia (MLA) beef carcass classification/grading 1:311 video image analysis 1:311 Meat Standards Australia grading program see Meat Standards Australia (MSA) grading program Meat animals see entries beginning animal Meatborne hazards, mitigation 2:218–224 concepts of hazard mitigation 2:218–219 legal framework and standards 2:219 mitigation ¼ surveillance þ intervention 2:219 responsibilities 2:219

economics of hazard mitigation 2:222–223 costs of intervention 2:223 costs of surveillance 2:222–223 evaluation of mitigation 2:223 trade-offs and optimization 2:223 who should pay for mitigation? 2:223 evaluation, definition 2:218 future directions 2:223 interventions for hazard reduction 2:221 corrective 2:222T costs 2:223 endpoints 2:221 integrated control along food chain 2:222 intervention options 2:221–222, 2:222, 2:222T preventive 2:222T surveillance systems 2:219–220 approaches to surveillance 2:220 costs of surveillance 2:222–223 coverage, definition 2:218 level of surveillance and mitigation 2:219–220 methods for assessing surveillance 2:221 objectives of surveillance 2:220 surveillance activities 2:220 surveillance designs 2:220–221, 2:221, 2:221T Meatborne parasites see Parasites Meatborne pathogens bacterial prevalence 2:309–310, 2:313–314T confirmation 2:310 enrichment 2:310, 2:313–314T isolation 2:310 screening 2:310 emerging see Emerging pathogens enumeration 2:310 direct plating 2:310 most probable number 2:310–311 resuscitation step 2:310 standard methods 2:309–310 see also individual pathogens The Meat Buyer’s Guides 1:459 Meat carcass anatomy see Carcass composition Meat color 1:244–251, 3:268, 3:397 aging conditions effect 1:339–340 assessment in meat products 3:278, 3:278F consumer reaction 3:14 cured meats see Cured meats, color deviations 1:339–345 definition 1:339 intrinsic/extrinsic factors 1:339 discoloration 3:14 irradiation-induced 2:142 lipid oxidation-induced 1:248 with time 1:340 effect of cooking 1:374 effects of cutting/mincing 3:14 electrical stimulation (ES)-mediated changes 1:490 factors contributing to 2:167–168, 2:169F hot-boned meats 1:455

511

irradiation effects 2:142 measurement 2:164, 2:167–168, 3:278 instrumental 2:168–170 Hunter Lab systems 2:169 portable machines 2:170, 2:170F recommended specifications 2:168, 2:169T percentage reflectance 2:169–170, 2:170F subjective scoring methods 2:170–171 theory 2:168 meat tenderness assessment and 3:458 modified/controlled atmosphere packaging and 3:9–10 muscle fiber types and 2:446 myoglobin effect see Myoglobin pork 3:365–366, 3:366F poultry 2:469 rigor mortis effects 1:339–340 stability, proteomic investigations 3:157 surface see Surface meat color two-shade (ham) 2:446 see also Blooming; entries beginning color; individual meats; Myoglobin; Pigments; Sensory aspects of meat quality Meat components 1:206, 1:235–243, 1:358 analysis final product composition for labeling see Chemical analysis, final product composition for labeling major chemical components see Chemical analysis, major meat components minor components see Chemical analysis, micronutrients and other minor meat components online see Online measurement, meat composition proximate composition see Raw material composition analysis domestication of animals affecting 3:361 major chemical components analysis see Chemical analysis, major meat components factors influencing 1:235–236 changes from birth to maturity 1:236, 1:236T species differences 1:236, 1:237T relationships 1:235, 1:236F modification by feeding practices 2:109 see also specific components Meat content, calculation 1:170 Meat discoloration see Meat color Meat emulsion(s) 1:283, 2:423 definition 1:283, 3:126, 3:261 formation, salt in 1:296–297 stability see Comminuted meat products, emulsion/batter stability see also Comminuted meat products; Emulsification; entries beginning emulsified Meat emulsion matrix see under Comminuted meat products Meat enhancement 1:280, 3:432 definition 1:274

512

Index

Meat enhancement (continued) effect on water-holding capacity 1:280 see also Tenderization ‘Meat factor’ 2:125 definition 2:124 Meat flavor see Flavor(s) Meat flavor deterioration (MFD) see Warmed-over flavor (WOF) Meat glue (transglutaminase) 1:301 Meat Industry Research Institute of New Zealand (MIRINZ) automated systems for ovine slaughter-line operations and 1:39, 1:49 waveform (electrical stimulation) 1:489–490 Meat juiciness see Juiciness Meat lipids see Fat; Lipid(s) Meat marketing, requirements/specification 2:231–235 assessment of adherence to product specifications 2:234 reasons for specifications 2:231–232 food safety and animal health and welfare 2:231–232 product differentiation 2:232–233 trade facilitation 2:232 recent development 2:234–235 specification attributes 2:233 animal production characteristics 2:233 processing characteristics 2:233–234 Meat meal (MM) 1:134 protein content 1:134, 1:135T Meat palatability 3:267–268 chemical characteristics 1:252–261 connective tissue influences 1:257–258 definition 1:252 fat/lipid effects 1:159, 1:222, 1:223F, 1:252–253, 1:253F health-conscious consumers 1:252 lean components contribution to 1:257 meat from double-muscled animals 1:467T, 1:469 mechanically recovered meat 2:274 muscle fiber 1:257 physical characteristics 1:252–261 quality grading scores and 1:252, 1:254F role of fat 2:450, 2:450F see also Sensory aspects of meat quality Meat pickles 1:541 definition 1:538 Meat pricing systems 2:248–254 demand curve 2:248 future systems 2:253–254 international aspects 2:253–254 price discovery 2:248, 2:248–250 pricing efficiency 2:250–252 benefit–cost assessments 2:251–252 consumer requirements 2:251 consumer signaling process 2:251, 2:252 definition/concept 2:251 USDA and 2:253 vertically integrated systems 2:251–252, 2:252 public policy issues 2:253 USDA 2:253 supply curve 2:248

transitions 2:252–253 consumer requirements influencing 2:252–253 exports and 2:253 fixed-cost investments 2:252–253 market complexity 2:253 US Choice beef demand index 2:248–250, 2:250F US consumption per capita 2:248, 2:249F US pork demand index 2:250, 2:251F US prices for beef/pork 2:248, 2:249F US total red meat and poultry consumption 2:250, 2:252F Meat processing see Processing Meat production environmental impact see Environmental impact, meat production genetic engineering of animals see Genetically engineered animals global 1:502, 1:502F optimization of efficiency and sustainability 3:427–430 livestock production 3:427–428, 3:428T new product development 3:428–429 processing optimization 3:428 quality management activities see Quality management activities/systems residues associated with see Residues, meat production-associated systems see Production systems trends 1:480 see also individual meats Meat production business and public policy 1:480–485 animal welfare 1:481 antibiotics 1:482–483 dietary guidelines 1:483 environmental stewardship and regulation 1:481–482 interaction with biofuel industry 1:484 internal business regulation 1:484 international trade 1:483–484 Meat products additives see Additives (meat/meat products) botulism incidents 2:332 canned 1:139 see also Canning comminuted see Comminuted meat products Commission of the European Communities definition 1:168, 1:168T complexity of market, prices and 2:253 fat in see Fat, in meat products formulation 1:444–445 functional see Functional food(s) labeling with nutrient claims 2:453–454, 2:454T microbial contaminants see Microbial contaminants, meat products new product development 3:428–429 nitrate concentrations 1:202–203, 1:202F see also Nitrate(s)

nitrite concentrations 1:202–203, 1:202F see also Nitrite(s) nitrosamine concentrations see Nitrosamines nutritional enhancement 2:452–453, 2:453T patenting 3:44 see also Patents, examples of as pathogen-introducing vehicle 1:29 product differentiation, market specifications and 2:232–233 quality, quality attributes of meat 3:159–160, 3:161T sensory assessment see Sensory assessment, meat species determination see Species determination thermophysical properties 3:460–464 microbial status and 3:460 transportation see Transport of meat/meat products see also individual products; Processed meat(s); specific regions Meat protein(s) 1:206, 1:237–239, 2:112–113, 2:118–119 amino acid balance 2:119 as bioactive protein source 2:119 bioavailability, muscle fiber types and 2:447 in comminuted meat products see Comminuted meat products consumption by food (and country) 2:113T content 2:111, 2:112 digestion 2:118, 2:119–120 effects of heating 1:404–409 chemical changes 1:404 connective tissue proteins 1:405 myofibrillar proteins 1:404–405 sarcoplasmic proteins 1:404 water-holding capacity 1:405–406 meat flavor development and 1:378–379 on meat microstructure 1:406–407 connective tissue changes 1:406–407, 1:406F effects of heating temperature on cooking losses and sarcomere length 1:407, 1:408F myofibrillar changes 1:406–407, 1:407F texture and tenderness of heated meat 1:407–408 energy intake, contribution to 2:112 factors influencing content in meat changes from birth to maturity 1:236, 1:236T fat content of meat 1:235, 1:236F species differences 1:237T functionality see Muscle proteins, functionality lysine in 2:112, 2:118–119 nutritional quality 2:112 cooking effect 2:112 quality, human diet 2:118, 2:118–119

Index

swelling of 2:423 definition 2:422 types 1:267, 2:112 myofibrillar (salt-soluble) see Myofibrillar proteins sarcoplasmic (water-soluble) see Sarcoplasmic proteins stromal (connective tissue) see Connective tissue proteins see also entries beginning protein; Nutrition (human) Meat protein-derived bioactive peptides, novel functional meat product development 2:35, 2:35T Meat quality beef see Beef quality breeding strategies and 1:19 see also Animal breeding, traditional canned meats, factors affecting 1:140–141 collagen cross-linking 1:326–327 differences among breeds 1:20 double-muscled animals 1:467T, 1:468–469 effect of electrical stunning 3:409–410, 3:410F effect of freezing see Freezing, effect on product quality effect of preslaughter stress see Preslaughter stress ethical 1:366 factors affecting in immediate postmortem period 1:454 freezing and see Freezing, effect on product quality genetic improvement role of molecular markers 1:12–13 see also DNA markers selection programs 1:23 see also Genomic technology/modern genetics, application in meat industry genetic parameters 1:20T, 1:21–22 major genes 1:13–14, 1:15T, 1:25T quantitative trait loci see Quantitative trait loci (QTL) genomic technology applications see Genomic technology/modern genetics, application in meat industry hot-boned meat 1:454–455 implications of natural curing 1:434 indicators 2:489 irradiation effects 2:142 meat pH and 1:257, 1:257F modeling see Meat quality modeling muscle connective tissue and see Connective tissue muscle fiber types and 2:442–448 see also Muscle fibers (myofibers), meat quality and online measurement see Online measurement, meat quality organic meat production 2:202–203 perimysium organization 1:325 pork see Pork quality postmortem glycogen breakdown 1:354 processed meat, microbial contamination intervention and 2:291–292

quality attributes of meat 3:159–160, 3:161T sensory aspects see Sensory aspects of meat quality technological, muscle fiber type affecting 2:445–446 thawing and see Thawing, quality aspects use of near infrared (NIR) spectroscopy meat quality measurement 2:491 meat quality prediction in commercial situations 3:76–77 see also Eating quality; Sensory assessment, meat Meat quality modeling 2:425–429 advantages 2:425 algebraic models 2:427–428, 2:427F approaches 2:425–426 causal model framework 2:426–427, 2:426F input selection 2:426 simplifications 2:426–427 variable definitions 2:427 component models 2:427–428 computer models 2:427–428 differential equations 2:427–428 future developments 2:429 pH change vs. temperature 2:427, 2:427F statistical framework 2:425–426, 2:428–429 Meat quality score (MQS), beef carcass classification/grading Australia 1:311–312, 2:429 Japan 1:313–314 Meat refrigeration facility model 2:436, 2:437F Meat research institutions 2:255–264 national 2:255–256T private industrial 2:262–263T provincial 2:257–261T scientists 2:255–264 Meat slicers 3:130 Meat stalls, wet markets 2:244 Meat Standards Australia (MSA) grading program 1:311F beef 1:311–312, 2:428 aging effects 2:429 carcass suspension method and 2:429 meat quality score 1:311–312, 2:428 modeling 2:428 updates 1:312–313 Palatability, Assessed Critical Control Point 1:311–312 Meat Standards Australia (MSA) index, beef carcass classification/grading 1:312–313 Meat Standards Australia (MSA) optimization, beef carcass classification/grading 1:312–313 Meat storage frozen see Frozen storage refrigeration see Refrigeration see also entries beginning storage Meat texture see Texture Meat toughness cold-induced 1:343 collagen crosslinks 1:258

513

definition 1:252 factors influencing 1:330, 1:330F mechanical measurements, in beef and lamb 2:494–495 muscle fiber protein concentration 1:253 see also individual meats Mechanical anemometers 3:54, 3:55F Mechanical conditioning advantages 3:145–146 cooking yield increases 3:145 costs 3:146 curing ingredients migration 3:144 cycles 3:144–145 disadvantages 3:146 labor requirements 3:146 meat product bind increases 3:144 meat temperature changes 3:144 over/underconditioning effects 3:146 pickle penetration 3:145 product flavor/aroma 3:146 protein solubilization 3:145 rest periods 3:144 sliceability increases 3:145 time–work intensity relationship 3:144 Mechanical energy, definition 1:508 Mechanically deboned tissue, definition 3:261 Mechanically recovered meat (MRM) 1:168, 2:270 composition 2:272–274 beef 2:273, 2:273T fish 2:272 pork 2:273, 2:273T poultry meat 2:272, 2:273T definition 2:270, 3:261 history 2:270 machines that remove meat from bone 2:270–271 names and pertaining legislation 2:271–272 palatability 2:274 safety 2:274 uses 2:272 Mechanically separated meat (MSM) 1:111, 2:271 in comminuted meat products 1:292 definition 2:231, 3:261 high pressure, definition 2:270 marketing requirements/specifications 2:235 see also Mechanically recovered meat (MRM) Mechanical meat recovery systems 2:270–271 Mechanical pulling see Dehiding (mechanical pulling) Mechanical refrigeration units 3:188 Mechanical stunning 3:413–417 abattoir audits 3:416 accurate shot application 3:414, 3:414F assessment of stun quality 3:414–415 automated systems 3:416, 3:416F physiology 3:413–414, 3:413F, 3:414T practical considerations 3:415–416 bulls 3:415, 3:415F safety 3:415, 3:416F

514

Index

Mechanical stunning (continued) typical system 3:415–416, 3:416F see also Stunning Mechanical tenderizing mechanisms see Tenderizing mechanisms, mechanical Mechanical vapor compression refrigeration 3:198–200, 3:199F components 3:198–199 Mechanization for task replacement, ovine slaughter-line operations 1:39–40, 1:49 Mechano growth factor (MGF) 2:50 Medication definition 2:204 see also Veterinary medicinal products (VMPs) Mediterranean 1:550–552 meat products 1:550–551, 1:550F, 1:551F European Union certifications 1:551 see also Dry-cured ham production; specific products Mediterranean diet 2:108T Mediterranean-type sausages 2:2 additives 2:2 ripening 2:2–3 modeling nature/dynamics of 2:5T, 2:6 see also Fermented sausages Medium of deMan, Rogosa and Sharpe (MRS), lactic acid bacteria enumeration 2:308T, 2:309 Melanoidins 1:391, 1:400 formation 1:400–401, 1:402F see also Maillard browning Melengestrol acetate (MGA) 2:66 implant dosage 2:63 mechanism of action 2:53 trenbolone and 2:63–64 Melt curve see Polymerase chain reaction (PCR) Membar 1:554 definition 1:553 Meningitis, definition 2:317 Merchandising factors, packages 3:20 Mercury contamination, fish 1:500 Mesoderm 2:71 definition 2:70 Mesophiles, definition 1:137, 2:285 Metabolic exhaustion, hurdle technology 2:345 Metabolic indices, somatotropin effects 2:77T Metabolic modifiers 2:62–69 beta-adrenergic agonists see Betaadrenergic agonists (BAA) definition 3:363 effects 2:62–63 meat tenderness 2:68 palatability, effects on 2:68–69 steroid hormones see Steroid hormones Metabolic syndrome 2:106 Metabolism, definition 2:75 Metabolizable energy (ME), in pig foods 2:458 Metal(s) black, as surface in food production environments/equipment 1:509T

as foreign body in meat 2:23, 2:23T detection 2:23–24, 2:24F see also Foreign bodies Metal detection, in meat 2:23–24, 2:24F see also Foreign bodies, technologies for detection in meat Metal ions, meat tenderization 3:432–433, 3:432F, 3:434–435T see also Calcium-activated tenderization Metametabolomics, definition 2:1 Methane 1:502 emissions, livestock production-related 1:504–505, 1:505F see also Biomethane production and cleanup; Greenhouse gases Methanogen, definition 1:71 Methanogen vaccines 1:73 Methemoglobin, definition 3:9 Methicillin-resistant Staphylococcus aureus (MRSA) 2:376–377, 2:415 environmental exposure to 2:418 prevalence in meat 2:376–377, 2:378T Methylation, fatty acid analysis 1:208 Metmyoglobin 3:397, 3:397F, 3:398 definition 3:9, 3:26, 3:70, 3:394 formation 3:27–28, 3:28 cured meats 1:417, 1:418F isosbestic point 3:72–73, 3:74F meat color and 2:167–168 oxygen partial pressure and 3:27–28, 3:27F in packaged fresh meats 1:246–248, 1:246F, 1:247T, 3:398 vacuum-packaged meats 3:28–29, 3:29, 3:32 Metmyoglobin reducing activity (MRA) 3:10–11 Metmyoglobin reductase 3:398 Mettwurst 3:245, 3:260, 3:264 definition 3:261 finished form 3:265T processing 3:265T Mexico antibiotic growth promotant policy 2:175T private industrial meat research institution 2:262–263T Microaerophiles, definition 1:137 Microarrays, detection of foodborne pathogens 2:296–297 Microbes definition 2:289 see also Microorganisms Microbial activity in meat/meat products control, need for 2:430 microbial dynamics 2:431 growth see Microbial growth preventive measures and intervention strategies 2:430–431 see also Fresh meat, decontamination; Processed meat, decontamination see also Microbial contaminants, meat products

Microbial contaminants, meat products pathogenic Escherichia coli 2:359 sources 2:289–290 see also Meatborne pathogens; Processed meat, microbial contamination; specific microbes Microbial evolution, dry curing and 1:427 Microbial growth description 2:431, 2:431F factors controlling, definition 2:431–432 growth boundaries 2:431–432, 2:431T qualitative description 2:432, 2:432F quantitative approach see Microbial responses, mathematical modeling influence of water activity 3:78–79, 3:78T meat thawing and 3:203–204, 3:204F Microbial indicators see Indicator organisms Microbial populations, canning process severity and 1:137–138 Microbial proteins, use in comminuted meat products 1:289T, 1:294 Microbial responses, mathematical modeling 2:430–435 approach 2:432–433 thermal processing in canning industry 2:432, 2:433F databases and user-friendly software packages 2:435 limitations and challenges 2:434–435 variation of key factors 2:433–434, 2:434F Microbial spoilage see Spoilage Microbial stability, fermented sausages 2:5–6 Microbial transglutaminase (MTGase), meat processing applications 1:294 Microbiological criteria, microbial contamination of fresh meat 2:287 Microbiological methods, fish inspection see Fish inspection Microbiological quality, effect of freezing 3:194 Microbiological risk assessment 3:229 Microbiological safety 2:430 Bacillus cereus see Bacillus cereus Clostridium botulinum see Clostridium botulinum Clostridium perfringens see Clostridium perfringens effect of freezing 3:194 emerging pathogens see Emerging pathogens fermented sausages 2:5–6, 3:253–254 intervention strategies 2:430–431 prions see Prions Salmonella see Salmonella Staphylococcus aureus see Staphylococcus aureus thermotolerant Campylobacter see Thermotolerant Campylobacter viruses see Virus(es), foodborne Yersinia enterocolitica see Yersinia enterocolitica Microbiology hot-boned meat 1:453–454 predictive

Index

databases 2:435 see also Microbial responses, mathematical modeling Micrococci, Staphylococcus aureus vs. 2:379, 2:379T Micronutrients human diet 2:120–121 iron 2:120–121, 2:124–125 selenium 2:121, 2:126 vitamins see Vitamin(s) zinc 2:121, 2:125–126 see also Iron; Selenium; Zinc in meat 2:124–129, 2:125T chemical analysis see Chemical analysis, micronutrients and other minor meat components consumption surveys and 2:124, 2:125T see also individual micronutrients Microorganisms brine concentration influences 1:296 chilling after cooking 3:182 involved in meat fermentation 2:3 irradiation effects 2:143 meat preservation patenting 3:47 see also Biopreservation rendering raw materials 1:128, 1:129T resistance to heat processing see under Canning rumen 2:471–472, 2:473T stress reactions, hurdle efficacy 2:345 see also entries beginning microbial; individual species Microwave(s) 1:373 definition 2:489 heating 1:388–389 thawing methods 3:206, 3:207 meat cooking 1:301, 1:373 meat quality measurement 2:494 Microwave-assisted extraction, veterinary drug residues 1:218 Microwave instruments, moisture analysis 1:182T, 1:184, 3:53 Middle East 1:553–554 meat products 1:553 made with minced meat and corned beef 1:553–554 pastrami 1:553 sausages 1:553 food preferences and 1:553 traditional meat dishes 1:554 Middles definition 1:33 pork, automatic cutting 1:34–35, 1:35F, 1:36F Mild alkaline cleaners 1:513 Milk, Mycobacterium avium subsp. paratuberculosis (MAP) contamination 2:342 Milk production, organic 2:201 Milk products 1:299 Milk proteins 1:291–292 as meat extenders 1:3–4 Mills, emulsion 3:130 Minced beef fat content 1:222

fatty acid composition 1:222, 1:233, 1:233F moisture diffusivity 3:463–464 shelf life, irradiation effects 2:143 yeasts in 2:398 irradiation effects 2:399–400 spoiled meat 2:399 Minced fish see Fish, minced Minced meats antioxidant addition 2:424 beef see Minced beef microbial spoilage 2:424 aerobic, factors affecting 3:390 Middle East meat products 1:553–554 see also Comminuted meat products; Mincing Mincer, definition 3:126 Mincers/grinders 3:128 bone separators 3:128–129, 3:128F in-line/pump 3:129 typical configuration 3:128F Mincing 2:422–424 advantages 2:423 effect on water-holding capacity 2:423, 2:423T disadvantages 2:423 microbial spoilage 2:424 oxidative changes 2:423–424 effects on meat color 3:14 equipment 2:422 as predrying treatment 1:474 Mineral requirements pigs 2:459, 2:460T poultry 2:464T, 2:465–466 Minerals, in meat 1:242–243, 2:124–125, 2:125T chemical analysis 1:214–215 see also Ash; individual minerals Minimum ventilation, chicken meat production systems 2:206–207 Minor meat components, chemical analysis see Chemical analysis, micronutrients and other minor meat components Mitochondria sarcoplasm 1:154F, 1:158F, 1:159, 1:162F thermogenesis 2:44 Mitochondrial DNA cattle breeds 3:358, 3:358–359 goats 3:359 heteroplasmy, cloned animals 1:88–89 poultry 3:360 sheep breeds 3:359 wild animals, domesticated 3:358 cattle 3:358 Mitotic clonal expansion, preadipocytes 2:45 Mixed myofibrillar protein gel 1:270 Mixer(s) batter (coating) 3:118–119 blender vs. 3:126 meat products 3:144 Mixer curing method, hides 1:115–116 Mixing equipment 3:126–130 cooking 3:127 cooling 3:127

515

definition 3:126 general considerations 3:127 other types of mixer/blenders 3:128 paddle mixers 3:126–127, 3:126F ribbon blenders 3:127, 3:127F vacuum 3:127–128 mm Hg, definition 3:26 Models deterministic, definition 2:430 stochastic, definition 2:430 see also specific models/types of modeling Modified atmosphere packaged meat, definition 1:76 Modified atmosphere packaging (MAP) 3:9–12, 3:79 advantages and disadvantages of caseready meat and central processing 3:10 Clostridium botulinum in meats and 2:333 color properties and 3:9–10 cooked hams 2:86 definition 3:1, 3:9, 3:9, 3:13, 3:19, 3:78 equipment see Packaging equipment film composition and gas permeability 3:11 hurdle technology and 2:346–347 injection enhancement of meat and 3:11–12 key factors for success in product quality 3:12 purpose of 3:9–10 role of gases 3:10 carbon dioxide 3:11 carbon monoxide 3:11 nitrogen 3:11 oxygen 3:10 see also High-oxygen packaging; Lowoxygen packaging see also Packaging, atmosphere for sea transport 2:236–237 spoilage in, factors affecting 3:391–392 see also Packaging films Modified Babcock method 1:182T, 1:183 Modified starches, as meat extenders 1:4 Moisture content 1:180, 1:236–237 analysis see Moisture content, measurement factors influencing 1:237 changes from birth to maturity 1:236, 1:236T fat content of meat 1:235, 1:236F species differences 1:237T lean meat 2:111 relationship with water activity (aw) 1:472, 1:472F see also Water-holding capacity Moisture content, measurement determining moisture content from temperature 3:54 dielectric moisture sensor 3:53, 3:53F gravimetric method 3:53 near-infrared reflectance 3:53–54 water activity meters 3:53, 3:53F see also Raw material composition analysis, moisture analysis methods Moisture control, ovens 3:137–138

516

Index

Moisture diffusion 3:463–464 definition 3:460 Mold(s) 2:395–404 acceptable ranges in food 2:397, 2:400T cell morphology 2:395 colony appearance 2:397 enumeration 2:396–397 slides with grids 2:397 viable cells 2:397 fermented meat products 2:402 food safety issues 2:402 identification 2:396–397 criteria 2:397 importance 2:395 in meats beneficial aspects 2:401–402 importance of 2:401 occurrence 2:401, 2:402T, 2:403–404T spoilage 2:401, 2:402 factors affecting 3:392–393, 3:392T mycotoxin production 2:401 spores 2:395 see also individual molds Molding, cooked ham production 2:84–85 Molecularly imprinted polymers (MIPs), veterinary drug residue extraction 1:218 Molecular marker definition 1:12 see also DNA markers Molecular methods Clostridium perfringens detection 2:336–337 thermotolerant Campylobacter detection 2:383 see also specific molecular methods Molecular serotyping, foodborne pathogens 2:297 Molluscs 3:381–383 bivalves (two piece shells) 3:383 single-shell 3:384–385 cephalopods 3:385–386 gastropods 3:385 see also individual species Momo/dumpling 1:541 definition 1:538 Monensin, as antibiotic growth promotants 2:175 Monoacylglycerol lipase 2:47 Monogastric(s) definition 2:111, 2:152 influence of feeds on manure nutrients 2:153–154 Monosodium glutamate (MSG) 1:9–10, 1:300 definition 1:7 Monounsaturated fatty acids 1:239–240 kangaroo meat 3:352 meat 1:222, 2:107 melting point characteristics 1:240T see also Fatty acid(s); Lipid(s) Monte Carlo simulation definition 2:430 in mathematical modeling of microbial growth 2:434–435 Moose, slaughter process 3:292

Morcilla 1:520–521, 1:520F Mordatella Bologna 1:551 Morphogens definition 2:50 embryonic growth 2:50 myogenesis 2:50 Mortadella 3:245 Most probable number (MPN) 2:301 definition 2:301 meatborne pathogens 2:310–311 Mother bag(s) definition 3:1, 3:13 flow wrap 3:7 snorkel machines 3:7 Motion sickness, pigs 3:97–98 Motor unit 1:153–154, 1:156F definition 1:148 see also Muscle contraction Mouthfeel 1:258 fermented sausages 2:4 MRSA see Methicillin-resistant Staphylococcus aureus (MRSA) Mton (million ton) 1:502 Mucor 2:395, 2:396F Multi-drug resistance in marine species 2:418 Salmonella 2:414 in wild birds 2:420 Multilayer films see Packaging films, multilayer Multilocus sequence typing (MLST) 2:299 Campylobacter jejuni identification 2:383–384 Salmonella epidemiological/outbreak investigation 2:369 Multineedle injection, brine see Brine, multineedle injection Multiple-locus variable-number tandem repeat analysis (MLVA) 2:299, 2:299F Salmonella epidemiological/outbreak investigation 2:369, 2:369F Multiple-needle pumping cure application 1:446 see also Brine, multineedle injection Multiplex polymerase chain reaction 2:295 Multispectral vision, foreign body detection 2:31 Multitarget preservation 2:345–346 Mu¨ncher WeiXwurst 1:535 definition 1:530 Municipal solid waste, management 2:157 Muridae 2:195–196 Muscle average growth impetus 2:59 classification 1:324–325 composition 1:180, 1:238, 1:238F connective tissue see Connective tissue contraction see Muscle contraction conversion to meat pH changes see under pH proteomic studies 3:156 see also Aging, meat; Cold shortening; Glycolysis; Rigor mortis; Rigor shortening

degeneration 1:344 stress-induced, beef 1:344 development see Muscle development DNA mass 2:77–78 enzymes see Muscle enzymes fascicles 1:323, 1:324–325 fibers see Muscle fibers (myofibers) fluid, definition 2:367 functions 1:323 glycolysis postmortem 1:354, 1:354F time course 1:355–356, 1:355T, 1:356F growth see Muscle growth high growth impetus 2:59 hyperplasia 2:77 steroid hormone effects 2:65, 2:65F hypertrophy see Muscle hypertrophy lipids fatty acid composition 1:224–226 see also Lipid(s) low growth impetus 2:59 mass, animal domestication affecting 3:361 myoglobin denaturation, pork muscle 1:339–340 postmortem changes 1:354, 1:355F abnormal 1:356 connective tissue changes see Connective tissue fast pH falls 1:356 incomplete pH fall 1:356, 1:356F structural 1:355–356 tenderness 1:356 water retention 1:356 proteins see Muscle proteins relaxed state 1:359F, 1:360, 1:361F RNA mass 2:77–78 somatotropin effects 2:78 structure 1:358, 1:359F, 2:442 organizational differences, pig muscles 1:324–325, 1:325F see also Connective tissue; Muscle fibers (myofibers) types connective tissue organization and 1:324–325, 1:326–327, 1:327 effect on electrical stimulation response 1:492 water-holding capacity see Water-holding capacity weight 2:77–78 see also Carcass muscle; Myofibril(s) Muscle contraction 1:157, 1:358, 1:359F, 1:360 control of 1:156 cycle 1:360, 1:361F definition 1:358 see also Muscle fibers (myofibers); Shortening Muscle development 2:70–74 embryonic/prenatal see Myogenesis endocrinology 2:74 postnatal 2:72 change in myofiber numbers 2:74 histochemistry 2:72–73 hyperplasia vs. hypertrophy 2:71F, 2:72 longitudinal growth of myofibers 2:74

Index

radial growth of myofibers 2:73–74 satellite cells 2:71F, 2:72 tapered myofibers 2:73 see also Muscle growth Muscle enzymes activity, curing factors affecting 1:427 chemical analysis 1:215–216 Muscle fibers (myofibers) 1:358, 1:359F, 2:70, 2:442–448 adhesion to perimysium 1:325 age-related changes 1:324 biochemistry, genomic technologies and 2:39–40 characteristics 2:442–444 composition 2:442 genetic factors affecting 2:445 contractile apparatus 1:156, 1:157F, 1:158F see also Contractile proteins; Muscle contraction definition 1:148, 2:70, 2:70, 2:442 denaturation 1:253 diameters 2:442 food safety and 2:447 histochemistry 2:444, 2:444T histoenzymology staining 2:444, 2:444T hyperplasia 2:72 hypertrophy vs. 2:71F, 2:72 see also Double muscling hypertrophy hyperplasia vs. 2:71F, 2:72 see also Muscle development, postnatal; Muscle hypertrophy identification of type 2:444 biochemistry 2:444–445 histochemistry 2:444, 2:444T light and dark bands 2:442 longitudinal growth 2:74 meat palatability and 1:257, 2:446 meat quality and 2:442–448 chilling of meat, meat fiber type 2:446 color (meat) 2:446 fiber type effect 2:445–446 flavor 2:446 nutritional quality and fiber types 2:447 salting, cooking 2:446–447 sensory and technological qualities 2:445–446 tenderness 2:445–446 water-binding properties 2:446 metabolism 1:155–157 aerobic 1:155–156, 1:162F anaerobic 1:155–156, 1:162F see also Fast-twitch fibers; Slow-twitch fibers muscle volume comprised of 2:442 nucleus 2:77 numbers in meat carcasses 1:152–153, 1:155T physiology 1:152–155 postrigor contractile state 1:255F protein classification 1:257 radial growth 2:73–74 secondary 2:71–72, 2:71F definition 2:70 structural proteins 1:257

structure 1:152–155, 2:442 see also Myofibril(s) tapered 2:73 type proportion, factors affecting 2:445 age 2:445 genetic factors 2:445, 2:445T nutrition 2:445 physical activity 2:445 temperature 2:445 types 2:442–444, 2:443F cancer risk association 2:447 effect on protein functionality gelling properties 1:271, 1:272F solubility 1:269–270 food safety and 2:447 identification see Muscle fibers (myofibers), identification of type in longissimus muscles 2:445T mammalian 1:157, 1:162 meat quality and see above nutritional quality affected by 2:447 type I (slow twitch, oxidative metabolism) 2:443 type IIA (fast twitch, intermediate metabolism) 2:443 type IIB (fast twitch, glycolytic metabolism) 2:443–444 type IIX (fast twitch, glycolytic metabolism) 2:443–444 ultrastructure 2:444F see also Fast-twitch fibers; Muscle contraction; Sarcomere; Slow-twitch fibers Muscle fluid, definition 2:367 Muscle growth 2:70, 2:75 allometry 2:70–71 see also Allometric growth patterns 2:57F, 2:58–59 gender differences 2:59 genetic variation 2:60 nutrition effects 2:60 see also Growth patterns physiology 2:77–78 regulation 2:77 satellite cell population 2:77 steroid hormone effects 2:65, 2:65F, 2:66F see also Muscle development Muscle hypertrophy beta-adrenergic agonists and 2:67 callipyge sheep 1:344 definition 1:465 somatotropin treatment 2:184 see also Callipyge/callipyge condition; Double muscling Muscle proteins functionality 1:267–273 definition 1:267, 1:267 factors affecting 1:267 solubility see Protein solubility water binding 1:267–268 definition 1:267 description 1:268 effect of phosphates 1:268, 1:268F

517

effect of salts 1:268, 1:297 see also Water-holding capacity see also Contractile proteins; Meat protein(s); Myofibrillar proteins Muscle-to-bone ratio 1:149T, 1:164–165, 1:165T cattle 3:331 Muscularly hypertrophied cattle see Double muscling Mussels 3:384 Mustard seed, as meat extender 1:5 Mutagens definition 2:100 in meat products 2:101 Mutations, carcinogenesis 2:100 Mutton flavor 3:276–277 lamb 1:260 global production 1:502F Kohlapuri see Kohlapuri mutton odor 2:495–496 see also Sheep Mutual recognition agreement (MRA) 2:146 Mycelium 2:395 Mycobacterium avium subsp. paratuberculosis (MAP) 2:342 Mycoplasma hypopneumoniae eradication programs, pigs 2:187 specific pathogen free pig programs 2:188 Mycotoxic molds, in dry fermented sausages, preventive measures 3:253 Mycotoxins 2:401, 2:402, 3:68 Myoblasts 2:50, 2:71, 2:71F definition 2:70 Myofibers see Muscle fibers (myofibers) Myofibril(s) 2:70 definition 1:148, 2:442, 3:431, 3:443 denaturation by cooking 2:446 by salting 2:446 features 1:155, 1:157F, 1:158F, 1:159, 1:163F in sarcoplasm 2:442 structure 2:442 Myofibrillar component, definition 1:252 Myofibrillar fragmentation index (MFI), meat tenderness measurement 3:458–459 Myofibrillar proteins 1:238, 1:238F, 1:267, 1:358 definition 1:329, 1:486, 3:267 effects of heating chemical changes 1:404–405 on meat microstructure 1:406–407, 1:407F enzymatic degradation endogenous enzymes 3:438 exogenous enzymes 3:441 see also Tenderizing mechanisms, enzymatic functionality 1:267 comminuted meat product processing and 1:284 emulsification 1:272, 1:272F, 1:273 gelation 1:270 effect of muscle fiber type 1:271

518

Index

Myofibrillar proteins (continued) effect of processing protocols 1:271 gel types 1:270 mechanism of gel formation 1:270–271, 1:271F solubility 1:269 effect of ionic strength 1:269, 1:269F effect of muscle fiber type 1:270 effect of phosphates 1:269 water binding 1:268 see also Muscle proteins, functionality juiciness and 1:257 meat tenderness and 1:257 see also Meat protein(s) Myofilaments structure 2:442 thin and thick 2:442 Myogenesis 2:50, 2:71 definition 1:465 insulin-like growth factors 2:50 morphogens 2:50 stages 2:71F degeneration 2:72 innervation 2:71F, 2:72 mesoderm 2:71 myoblasts and myotubes 2:71, 2:71F secondary myofibers 2:71–72, 2:71F Myogenic regulatory factors 2:50 Myoglobin 1:239, 1:244, 3:397 amino acid sequences 1:244–245, 1:246F chemistry 3:26–28 concentrations in muscle tissues of various species 1:239T, 3:397 pigs 1:239T, 3:366 dark, firm and dry meat 1:343 definition 1:7, 1:370, 2:446, 3:1, 3:13, 3:19, 3:70, 3:394 denaturation meat color and 1:371 pork muscle 1:339–340 meat color and 2:167–168, 2:446 effect of cooking 1:371 see also Blooming; Myoglobin oxygenation pigment changes in fresh meat, normal cycle 3:397, 3:397F redox forms oxygen partial pressure and 3:27, 3:27F in packaged fresh meats 1:246–248, 1:246F see also Carboxymyoglobin; Deoxymyoglobin; Metmyoglobin; Oxymyoglobin structure 1:244, 1:244F, 1:245F see also Pigments Myoglobin measurement, near infrared spectroscopy, meat quality assessment 2:491 Myoglobin oxygenation 3:14, 3:397, 3:397F modified atmosphere packaging and 3:10 see also Blooming; Oxymyoglobin Myosin 1:157, 1:158F, 1:238, 1:358 definition 1:358, 1:370, 2:442 denaturation 1:371 in vitro, modeling 2:428 heavy chain isoforms 2:442, 2:443F

definition 2:442 identification, biochemical 2:444 heavy chains 2:442 histochemical identification 2:444 light chains 2:442 water binding 1:257 see also Actomyosin; Muscle contraction; Myofibrillar proteins Myosin ATPase 1:155, 1:160F Myosin gel 1:270 Myostatin adipocyte differentiation 2:51 definition 1:465, 2:56, 3:357 fetal muscle development 2:50–51, 2:76 function 1:466 postnatal muscle growth 2:54 Myostatin gene (GDF8) 1:13, 1:15T, 1:25T mutation in double muscling 1:343–344, 1:465–466, 1:466, 2:60, 2:72, 2:76 Myotubes 2:71, 2:71F definition 2:70 Mysliwska sausage 1:558–559, 1:559 Mytilus edulis (blue mussel) 3:384

N Nakanek 1:553 definition 1:553 Namibia, game meat industry 3:349 Nappings, definition 3:272, 3:273 Nate-yakhni 1:539 National Association of Meat Processors, pork bellies trimming specifications 1:54 National Beef Quality Audit (NBQA) 3:174–176 National Cholesterol Education Program (NCEP) 2:106 National meat research institutions 2:255–256T National Pork Board, Transport Quality Assurances program see Transport Quality Assurances program National Residue Control Plans (NRCPs) 3:218–219, 3:219T definition 3:214 National Shellfish Sanitation Program (NSSP) definition 2:301 indicator organisms, historical perspective 2:301 Native starches 1:4 classification 1:4 as meat extenders 1:4 Natural antimicrobials, as hurdle technology 2:346 Natural casings (sausages), definition 2:340 Natural curing 1:430–435 definition 1:430 manufacturing ingredients 1:432–433 natural antioxidants 1:433 natural binding and texturizing agents 1:433 natural curing adjuncts 1:433

natural curing agents 1:432–433 natural nitrate sources 1:432–433 natural preconverted nitrate sources 1:433 natural sources 1:8, 1:432–433 natural flavorings 1:433 natural preservatives 1:433 nitrate-reducing starter cultures 1:433 manufacturing processes 1:433–434 comminuted sausage manufacture 1:434 general procedures 1:433–434 whole muscle product manufacture 1:434 manufacturing systems 1:430–431 culture system 1:431 prebrine system 1:431 preconverted system 1:431 see also Functional ingredients, meat products; Naturally cured meat products Naturally cured meat products 1:8 challenges 1:434 quality implications 1:434 safety implications 1:434–435 labeling 1:431–432 general regulations 1:432 terms 1:431–432 see also Natural curing Natural nitrate- and nitrite-free cured meats 1:450–451, 1:451T Natural smoke, warmed-over flavor prevention 1:414 ‘Nature’ of animals animal welfare and 3:110 see also Animal behavior Near infrared reflectance (NIR) measurement 3:71, 3:71F moisture content 3:53–54 raw material composition analysis 1:185 Near infrared (NIR) spectroscopy 1:175 chemometrics and 3:71–72 definition 1:180, 3:70, 3:70 fish freshness assessment 2:11 meat composition analysis 1:175, 1:185, 2:483–484 fat analysis 1:208 protein analysis 1:209 meat quality measurement 2:491 meat quality prediction in commercial situations 3:76–77 meat tenderness measurement 2:491, 3:458 prediction of meat attributes from intact muscle 3:70–77 meat microstructure 3:72, 3:72F, 3:73F, 3:74F meat quality prediction in commercial situations 3:76–77 postrigor changes 3:72–73, 3:73–76, 3:74F, 3:75F prerigor changes 3:72–73, 3:73, 3:74F, 3:75F principles 3:70–72 instrumentation 3:71, 3:71F

Index

vibrational modes of molecules 3:70–71, 3:71F Near infrared transmission (NIT) measurement 3:71 raw material composition analysis 1:185 Neck cutting 1:561–562 carcass quality 1:563 meat quality 1:563 pain during 1:562 Necrotic enteritis, prevention, ionophore antibiotics 2:175 Needles, brine injectors 3:124, 3:124F design 3:124 Nematodes 3:35–38T see also Parasites Nentsi 2:194 Neolithic, definition 3:357 Neonatal listeriosis 2:351 Neospora caninum 3:35–38T, 3:39 Nervous tissue, growth patterns 2:57, 2:57F Net energy (NE) in pig foods 2:458 requirement, growing pigs 2:461, 2:461T Net feed efficiency, definition 3:328 Netherlands, meat research institutions national 2:255–256T provincial 2:257–261T Neuropil, definition 2:362 Neurotoxin, botulinum 2:330, 2:331–332 Neurotransmitters, definition 3:407 Neveila 3:210 definition 3:209 New Animal Drug Application (NADA), genetically engineered food animals 1:95 Newborns, brown adipose tissue 2:43 New Zealand antibiotic growth promotant policy 2:175T electrical stunning, cattle 1:488 meat research institutions national 2:255–256T provincial 2:257–261T see also Meat Industry Research Institute of New Zealand (MIRINZ) venison production 3:291, 3:347–348 Niacin 2:127 sources and daily requirements 2:127 Nisin 1:10 Bacillus cereus control 2:328 Clostridium botulinum control 2:334 as hurdle technology 2:346 Nitrate(s) 1:8, 1:298, 1:418–419, 1:436 analysis 1:203 carcinogenicity 1:436 chemistry 1:201 concentrations in meat products 1:202–203, 1:202F definition 3:64 forms 1:298 human exposure adverse effects 3:68 sources and estimates 1:437–438 in human physiology 1:436, 1:437

natural sources 1:8, 1:423–424, 1:432–433 preconverted 1:433 pathways in human body 1:436, 1:438–440, 1:439F, 1:440F regulations/legal requirements 1:201T, 1:419, 1:430, 1:431T, 3:223 toxicity 1:205, 1:205T, 1:437–438 warmed-over flavor prevention 1:414 see also Curing agents; Nitrite Nitrate-free cured meats 1:450–451, 1:451T see also Uncured processed meats Nitrate-reducing starter cultures, natural curing 1:433 Nitrate reduction, human 1:438, 1:439F, 1:440F Nitric oxide (NO) 1:436–441 biochemistry 1:436–437 insufficiency in humans, therapeutic aspects 1:440 pathways in human body 1:438–440, 1:439F, 1:440F physiology 1:436–437 reaction with meat pigments 1:417, 1:418F see also Curing; Curing agents; Functional ingredients, meat products Nitric oxide myoglobin cured color development 1:298 vacuum-packaged meat 3:32 Nitric oxide synthase (NOS) 1:437 Nitrite(s) 1:7, 1:298, 1:418–419, 1:430, 1:436, 1:442, 1:443, 3:80 analysis 1:203 antioxidant mechanisms 1:414 carcinogenicity 1:436 see also Nitrosamines changes during storage 1:203, 1:203T chemistry 1:201–202, 1:201F, 1:202T Clostridium botulinum control 2:334 concentrations in meat products 1:202–203, 1:202F cooked sausage 3:242 cured color development 1:298 definition 3:64 effects in meat products 1:7–8, 1:203–204, 3:68 flavor 1:298 in food safety 1:298 functions 1:298, 1:418 human exposure adverse effects 3:68 sources and estimates 1:437–438 in human physiology 1:436, 1:437 maximum level regulations 1:298 see also regulations/legal requirements (below) pathways in human body 1:436, 1:438–440, 1:439F, 1:440F as quality indicator 1:298 reduction in cured meats 1:423–424 regulations/legal requirements Canada 1:418, 1:443 European Union 1:200, 1:201T, 1:443, 3:223 US 1:419, 1:430, 1:431T, 1:443

519

toxicity 1:8, 1:205, 1:205T, 1:437–438, 3:80 warmed-over flavor prevention 1:414 Wiltshire bacon flavor 1:62 see also Curing; Curing agents; Sodium nitrite Nitrite burns 1:298 Nitrite-cured meat flavor development 1:381–383, 1:383F see also Curing; Curing agents; Nitrite(s) Nitrite-free cured meats 1:450–451, 1:451T see also Uncured processed meats Nitrite reduction, in humans 1:438, 1:439F, 1:440F Nitrogen 1:502 environmental impacts 1:503–504 in gas stunning 3:402 mechanism of induction of unconsciousness 3:402 liquid see Liquid nitrogen in manure see Manure nutrients meat packaging role 1:301, 3:11 protein formation 1:353 Nitrogen-containing compounds, generated via Maillard reaction see under Maillard reaction Nitrogen cycle, human 1:438–440, 1:439F Nitrogen dioxide, pinking reaction and 3:137 Nitrogen factor, added water calculation 1:170–171, 1:170T, 1:299 Nitrosamines 3:223–224 carcinogenic potential 1:298 concentrations, meat products 1:204–205, 1:204T raw fermented sausages/raw ham 3:224 definition 1:7, 1:430, 3:221 formation 1:8, 1:204–205, 1:204F, 1:436, 3:223–224 factors influencing 3:223–224 Nitrosation, heme iron effect, cancer and 2:122–123, 2:122F N-Nitroso compounds definition 2:100 formation, heme iron role, cancer and 2:122–123, 2:122F smoked foods 3:324 Nitrosomyochrome see Nitrosylhemochrome/ nitrosohemochrome N-Nitroso pathway, heme iron role, cancer and 2:122–123, 2:122F Nitrosylhemochrome/nitrosohemochrome definition 1:7 oxidation 3:29 Nitrosylmetmyoglobin 1:417, 1:418F Nitrosylmyoglobin formation, cured meats 1:417, 1:418F Wiltshire bacon color 1:62 Nitrous acid 1:298 Nitrous oxide 1:502 emissions, livestock production-related 1:505, 1:505F see also Greenhouse gases nm, definition 3:70

520

Index

NMKL (Nordic Committee on Food Analysis) chemical standards and official methods on meat and meat products 1:197 method development process 1:195, 1:196F Noise, effect on animal behavior 3:86 Nonenzymatic browning see Maillard browning Nonesterified fatty acids definition 2:79 see also Fatty acid(s) Nonfat dried milk (NFDM) 1:291 Nonfat dried milk solids (NFDMS) definition 1:1 use as meat extender 1:3–4 Nonfood contact surfaces 1:509 Nongenomic steroid actions definition 2:62 implanted steroids 2:64 Nonheme iron see Iron, nonheme Noninfectious diseases pigs 2:186 see also specific diseases Nonionizing radiation 2:140–141 definition 2:140 Nonleavened systems, coating configurations 3:114F, 3:116–117, 3:118F Nonlinearity error, thermometer calibration 3:61, 3:61F Nonmeat ingredients addition to comminuted meat products, emerging trends 1:287–288 see also specific ingredients Nonmeat proteins 1:289–295 addition to comminuted meat products, emerging trends 1:287 animal proteins 1:289T, 1:291–292 blood proteins 1:292 connective tissue proteins 1:293 egg proteins 1:292–293 mechanically separated meat 1:292 milk proteins see Milk proteins surimi and surimi-like proteins 1:292 see also Surimi functions in comminuted meat products 1:289 composition for nutrition and health purposes 1:291 economics 1:289 functional properties 1:289–290, 1:290F, 1:291T emulsifying properties 1:290 gelation 1:290–291 water- and fat-holding properties 1:289–290 microbial proteins 1:289T, 1:294 plant protein sources 1:289T, 1:293 corn proteins 1:294 soy proteins 1:293 vegetable proteins, other 1:294 wheat proteins 1:293–294 see also Extenders; Functional ingredients, meat products Nonpreservative packaging 3:2 tray overwrap 3:2 machines 3:2, 3:3F

wrapping 3:2 see also Packaging Nonprotein nitrogen compounds, in meat 1:237–239 Nontarget bacteria, definition 2:412 Noradrenaline 2:177 growth effects 2:53–54 lipolysis 2:47 thermogenesis 2:44 Norepinephrine see Noradrenaline Norovirus 2:20, 2:391, 2:392F classification 2:391 genome organization 2:391 human infection 2:20, 2:391 symptoms 2:20 zoonotic transmission 2:20, 2:391–392 North American Free Trade Agreement (NAFTA) 1:483 definition 1:480 North American meat products 1:555–557 barbecue 1:556–557 definition 1:555 Buffalo/hot wings 1:557 chili con carne 1:557 hamburger/ground beef patties 1:556 Lebanon bologna 1:556 pemmican 1:555 restructured jerky 1:555–556 scrapple 1:556 summer sausage 1:556 whole-muscle jerky 1:555 Northern-type sausages 2:2 additives 2:2 flavor development 2:4 ripening 2:2–3 modeling nature/dynamics of 2:5T, 2:6 smoking 2:3 see also Fermented sausages Norway, meat research institutions national 2:255–256T provincial 2:257–261T Notification definition 2:145 procedure, laboratories see under Laboratory accreditation Nuchal ligament 1:149–150, 1:239 Nuclear magnetic resonance (NMR) spectrometry 1:175–176 definition 1:180 fat analysis 1:208 phosphorus-31, fish freshness assessment 2:11 raw material composition analysis 1:185–186 Nuclear reprograming (epigenetic reprograming), definition 1:83 Nuclear transfer (NT) carcass-recovered cells 1:86F, 1:89 complete reprograming 1:87 definition 1:83 donor cell differentiation 1:87 efficiency 1:83, 1:87 embryonic vs. somatic cell cloning 1:87 gene targeting and 1:91 genetic gain increases 1:89 genetic identity of clones 1:88–89

historical aspects 1:84 incomplete reprograming 1:87–88 parturition difficulties 1:88 phenotypic outcomes 1:87 placental abnormalities 1:87–88 long-term consequences 1:88 methodology 1:83, 1:84–87, 1:86F culture systems 1:87 donor cell injection 1:87 embryo activation 1:87 embryo reconstruction 1:87 oocyte enucleation 1:84–87 uteri transfer 1:87 mitochondrial DNA heteroplasmy 1:88–89 phenotypic identity of clones 1:88–89 postnatal viability 1:88 somatic cell types used 1:84 transgenerational effects 1:88, 1:88F transgenic animals 1:91 see also Cloning Nuclei, sarcoplasm 1:154F, 1:158F, 1:159 Nucleic acid probe, definition 2:285 Nucleotides degradation during dry curing 1:427 as flavor potentiators 1:300 Nucleotide substitutions, definition 2:294 Nu¨rnberger Rostbratwurst/Nu¨rnberger Bratwurst 1:537 definition 1:530 Nutraceuticals 2:130–134 definition 2:32, 2:33–34, 2:130 examples of animal-derived nutraceuticals 2:131 bile acids 2:131 carnitine 2:34, 2:34F, 2:131–132 conjugated linoleic acid 2:34–35, 2:34F, 2:132 glucosamine and chondroitin sulfate 2:132–133 heme iron 2:133 omega-3 fatty acids 2:133 vitamin D 2:133–134 government regulations 2:130–131 see also Functional food(s) Nutrient balance, farm 2:153 Nutrient claims, meat product labeling 2:453–454, 2:454T Nutrient competition, bacteria 1:77 Nutrient requirements, poultry see under Poultry nutrition Nutrients, manure see Manure nutrients Nutrient supply, response in pigs 2:456–457 Nutrient use, environmental impacts see Environmental impact, meat production Nutrition (human) 2:118–123 cancer association with meat see Cancer fat 2:121–122 gender issues and 2:139 lean beef, role 2:107 meat in 2:118–123 micronutrients see Micronutrients; Vitamin(s) obesity and see Obesity

Index

proteins (from meat) 2:111, 2:112–113, 2:118–119, 2:123 amino acids 2:119 bioactive peptides see Bioactive peptides classical criteria for evaluating 2:118–119 daily requirement 2:112–113 deficiency in vegetarians 2:138 digestion rate 2:118, 2:119–120 quality definition 2:118 see also Meat protein(s) Nutrition (livestock) effects, growth patterns 2:60 muscle fiber type affected by 2:445 pigs see Pig nutrition poultry see Poultry nutrition quality, muscle fiber types 2:447 ruminants see Ruminants, feed/feeding see also entries beginning feeding; Feed(s) Nutritional benefits, nonmeat proteins 1:291 Nutritional composition finfish 3:336–342, 3:342T shellfish 3:380 see also individual meats Nutritional deficiencies, muscle degeneration 1:344 Nutritional enhancement, meat products 2:452–453, 2:453T Nutritional labeling 1:167, 2:107–109, 2:449 analytical methods see Chemical analysis, final product composition for labeling calculations 1:170 added water 1:170–171 energy values 1:171, 1:171T meat content 1:170 cardiovascular disease prevention 2:107–109 claims 2:109 current requirements 1:167–169 European Union Regulation 1:167, 1:168F databases 1:169 definition 1:167 nutrient claims on meat products 2:453–454, 2:454T Nutritionally complete media 2:306 Nylons, packaging film chemistry 3:21–22

O Obesity 2:105–110, 2:109 cardiovascular disease and see Cardiovascular disease (CVD) global problem 2:105 leptin resistance 2:54 management/treatment dietary guidelines 1:483 strategies 2:109 Ochratoxin(s) 2:402 Ochratoxin A 2:401 Octopus 3:386, 3:386F

Odor(s) chemical analysis 2:495 boar taint 2:495 potential instrumentation for odor compounds 2:496 sheep meat taints 2:495–496 effect of cooking 1:374–375 measurements 3:278–279 meat flavor and 1:377–378 see also Aroma Odor threshold values (OTVs) 1:377 desirable meaty aromas of cooked meat and 1:381 Offal definition 3:328, 3:332 dressing percentage 3:332–333 Off-flavors 1:410 irradiation-induced 2:142, 2:144 poultry, nutrition and 2:469 see also Warmed-over flavor (WOF) Office International des Epizooties (OIE) see World Organization for Animal Health (OIE) Off-odors, irradiation-induced 2:142, 2:144 Ohmic heating 1:389 OIE see World Organization for Animal Health (OIE) Oil contamination, meat 2:23, 2:23T Oil frying 1:388, 1:388 Oilseed protein ingredients, use in comminuted meat products 1:294 Oil tanning method 1:121 Oily bird syndrome 2:469 Oleic acid 1:224 definition 2:111 dietary enrichment in pigs, effects 1:227–228 structure 1:229F see also Fatty acid(s) Oleic acid oxidation, warmed-over flavor 1:411 Oleoresins 1:9, 1:305 Oligofructose definition 1:1 as meat extender 1:4–5 Omasum 2:471, 2:471F, 2:472F Omega-3 fatty acids 1:240, 2:116 as animal-derived nutraceuticals 2:133 fish oils 1:132T, 1:133 in meat 2:116 see also Polyunsaturated fatty acids (PUFAs) Omega-6 fatty acids fish oils 1:132T, 1:133 in meat 2:116 see also Polyunsaturated fatty acids (PUFAs) One-humped dromedary (Camelus dromedarius) 3:354 129 Sv mouse model, uncoupling protein 1 2:44 On-farm handling definition 1:366 pigs, meat quality and 1:366–367 see also Animal behavior, during handling and transport

521

Online instrumentation definition 1:316 pig carcass classification see Pig carcass classification, Europe see also Online measurement, meat composition; Online measurement, meat quality Online measurement, meat composition 2:480–488 computed tomography 2:487 future perspectives 2:487 near infrared spectroscopy 2:483–484 optical systems 2:481–482 optical sorters 2:481–482 video image analysis 2:482, 2:482F performance of methods 2:480–481, 2:481F radioactive isotopes 2:485 total body electromagnetic conductivity 2:484–485 ultrasound 2:482–483, 2:483F X-ray systems 2:485 dual-energy X-ray 2:483F, 2:485–487, 2:486F, 2:487F single-energy X-ray 2:485 X-ray-based contaminant detection 2:485 see also Pig carcass classification, Europe Online measurement, meat quality 2:489–497 dual-energy X-rays 2:494 electrical measurements 2:492–493 impedance 2:493 marbling in beef 2:493–494 pale, soft, exudative and water-holding capacity 2:493 pH 2:492–493 see also pH, measurement, meat fat softness in pork 2:492 mechanical measurements of toughness in beef and lamb 2:494–495 microwaves 2:494 odors see Odor(s), chemical analysis optical measurements 2:489–490 near infrared spectroscopy 2:491 pale, soft, exudative 2:490 marbling and, in pork 2:490–491 surface meat color 2:491–492 Oocyte, definition 1:83 Oospores 2:395 Opposition, patents 3:48 Optaflexxs 2:177, 2:179, 2:179–180 Optical measurements definition 2:489 meat composition see Online measurement, meat composition meat quality see Online measurement, meat quality see also specific techniques Optical sorters, meat composition measurement 2:481–482 Ordinary differential equations (ODEs), refrigeration process models 2:439, 2:440 Organic acid(s) carcass treatment 2:277

522

Index

Organic acid(s) (continued) definition 2:276 use on beef carcasses 3:289 as hurdle technology 2:346 meat tenderization 3:433, 3:436T processed meat decontamination 2:282 production by lactic acid bacteria 1:77 Organic cured meat products 1:430 labeling 1:431–432 general regulations 1:432 terms 1:432 see also Natural curing Organic meat production 2:199–203 broilers 2:201–202, 2:205 cattle 2:201 guidelines and regulations 2:199–200 European Union 2:199, 2:200 pork 2:200–201, 2:200F product quality 2:202–203 sheep 2:201 Organs embryonic growth 2:50 growth, relative order 2:57, 2:57F see also Growth patterns see also specific organs Organ tissues, aerobic spoilage, factors affecting 3:390 Osmolality, muscle, postmortem changes 3:432, 3:432F Osmophiles, definition 1:515 Osteocytes 1:163–164 Ostrich 3:372 carcass yield 3:346T electrical stunning 3:411 muscle cuts 3:347, 3:347T nutritional value/nutrient composition of meat 3:346T, 3:371T, 3:372–373 processed meat products 3:347, 3:348T production systems 2:191 trends 3:372 slaughter process 3:292–293 Outdoor systems definition 2:211 pig production 2:216, 2:216F Ovenable films 3:24 Oven design, control of temperature variation 3:139 Oven drying, moisture analysis 1:182T, 1:184 Ovens see Cooking equipment Overland transport, meat/meat products 2:237–238 Overweight cardiovascular disease and 2:105, 2:106 global problem 2:105 see also Obesity Overwrapping/overwrap packaging 3:13–18 definition 3:1, 3:19 management practices and systems to enhance overwrapping 3:16 commercial packaging situations 3:17–18 cutting and display in local outlets 3:16–17 improving overwrap systems 3:17

retail losses 3:16 meat pigment chemistry and 3:14 microbial effects 3:16 problems encountered with overwrap 3:15–16 requirements for overwrapped packages 3:14 duration of acceptable retail display 3:15 films used 3:15 types of tray 3:15 see also Tray overwrap Ovine definition 1:235 see also entries beginning lamb; Sheep Ovine placental lactogen (OPL), fetal growth 2:51 Ovine somatotropin (oST) administration patterns 2:182 average daily gain 2:181–182 carcass quality 2:181–182 meat collagen content 2:184 meat color 2:184 optimal dose 2:182 performance 2:181–182 Oxazoles, formation via Maillard reaction 1:396 Oxazolines, formation via Maillard reaction 1:396 Oxidase test, Enterobacteriaceae 2:309 Oxidation definition 3:1, 3:13, 3:19 spoilage and see Spoilage, factors affecting Oxidative capacity, muscle 1:346 Oxidative changes, minced meats 2:423–424 Oxtail 1:109 removal 3:288 Oxygen, role in meat packaging 3:10–11 see also High-oxygen packaging; Lowoxygen packaging Oxygenation definition 3:2–1, 3:13, 3:19 myoglobin see Myoglobin oxygenation Oxygen consumption, muscle 1:346 Oxygen-containing compounds, generated via Maillard reaction 1:394F, 1:395F, 1:396 Oxygen permeability, packages 3:20, 3:20T definition 3:2, 3:13, 3:19 Oxygen scavengers definition 3:2 warmed-over flavor prevention 1:414 Oxygen scavenging, modified atmosphere packaging 3:11 Oxygen tension, definition 1:137 Oxymyoglobin 3:14, 3:27–28, 3:397, 3:397F definition 3:9, 3:26, 3:70, 3:394 isosbestic point 3:72–73, 3:74F oxygen partial pressure and 3:27–28, 3:27F in packaged fresh meats 1:246–248, 1:246F, 1:247T see also Blooming; Myoglobin; Myoglobin oxygenation

Oysters 3:383, 3:383F edible species 3:383T Ozone irradiation-induced 2:142 microorganism inhibition 1:301

P Paca 2:196 Pace boning, definition 1:33 Pacific crayfish 3:381 Packaged fresh meats, myoglobin redox forms in 1:246–248, 1:246F, 1:247T deoxymyoglobin see Deoxymyoglobin Packages cost 3:20 definition 3:19 flexible film, defects 3:24 functions/properties 3:19–20 barrier properties 3:20 definition 3:1, 3:19 labels 3:19–20 merchandising factors 3:20 protective functions 3:19–20 strength factors 3:20 visual 3:20–21 permeability 3:20, 3:20T factors affecting 3:20 oxygen see Oxygen permeability quality assurance 3:24 strength factors 3:20 see also Packaging films Packaging active see Active packaging anaerobic, with blooming agents 3:23 atmosphere controlled see Controlled atmosphere packaging (CAP) effects on bone marrow 3:11 effects on cooked color 3:11 modified see Modified atmosphere packaging see also Modified atmosphere packaging (MAP), role of gases cooked hams 2:85–86 cook-in 3:23–24 definition 3:19 dry-cured hams 2:90–91, 2:91 films see Packaging films before freezing, effect on product quality 3:191–192 materials oxygen permeability 1:301 properties 1:301 see also Packaging films meat aging and 1:337 nutrient claims 2:449–454 see also Nutritional labeling overwrap see Overwrapping/overwrap packaging product development 3:429 quality assurance 3:24 residues from 3:224 sensory aspects of meat quality and 3:270

Index

thermal pasteurization during, processed meat 2:281 thermoformed definition 3:2, 3:19 see also Thermoforming two-phase see Two-phase packaging vacuum see Vacuum packaging warmed-over flavor prevention 1:414 see also Nonpreservative packaging; Overwrapping/overwrap packaging Packaging equipment 3:1–8 nonpreservative packaging, tray overwrap machines 3:2, 3:3F preservative packaging 3:2–3 controlled- and modified-atmosphere packaging 3:5–6 CAPTECH chamber snorkel machines 3:6–7, 3:7F, 3:18 mother bag flow wrap 3:7 mother bag snorkel machines 3:7 preformed trays see Preformed trays two-phase packaging 3:7–8 vacuum packaging see Vacuum packaging, equipment Packaging films 3:19–25 chemistry 3:21 acrylonitriles 3:22 ethylene vinyl alcohol 3:21 ionomers 3:21 nylons 3:21–22 polyesters 3:21 polyethylenes and copolymers 3:21 polymer chemistry 3:21 polypropylenes 3:22 polystyrene 3:22 polyvinyl chloride 3:21 Saran 3:21 special film properties 3:22 composition, modified/controlled atmosphere packaging 3:11 for cured meats, oxygen permeability 3:30 multilayer 3:22 anaerobic packaging with blooming agents 3:23 coating 3:22 coextrusion 3:22 cook-in packaging 3:23–24 film layer arrangement 3:22 lamination 3:22 ovenable films 3:24 retort pouch 3:24 sealing 3:22–23 thermoforming see Thermoforming overwrapped packages 3:15 quality assurance 3:24 for vacuum packaging see Vacuum packaging see also Packages Paddle mixers 3:126–127, 3:126F, 3:144 Paddles, as driving aids 3:87 PAGE (polyacrylamide gel electrophoresis), meat species determination 2:266 Pain animal welfare and 3:110 avoidable, definition 3:418 capability to experience

criteria to determine 3:343 finfish 3:342–343 shellfish 3:386 Paint, as surface in food production environments/equipment 1:509T Pakistan, meat products see Indian subcontinent, meat products Palatability see Meat palatability Pale, soft, and exudative (PSE) condition in meat 1:340 beef 1:343 chicken and turkey meat 1:343, 3:370 definition 1:339, 2:489 degenerated meat vs. 1:344 fast pH falls, postmortem 1:339–340, 1:340F, 1:356 measurement electrical 2:493 optical 2:490 modeling 2:428 pork 1:145, 1:146, 1:242, 1:263, 1:340–341, 3:365–366 acid meat vs. 1:341 halothane-sensitive animals 1:341 harvest muscle temperature and 1:342 lairage period and 1:367, 1:367T measurement 2:490–491 poor chilling 1:342 preslaughter stress and 1:342, 1:366, 3:268–269 strategies to reduce 1:147 stress-induced 1:341–342, 1:342F poultry 1:145, 1:343, 3:370 preslaughter stress and 3:100 pork 1:342, 1:366, 3:268–269 rigor mortis and 1:362 warthog 3:352 water-holding capacity and 2:164–165 Palmitic acid 1:224–225 definition 2:111 see also Fatty acid(s) Palmitoleic acid 1:224 stearic acid vs., subcutaneous adipose tissue lipids 1:232, 1:232F see also Fatty acid(s) Pan broiling 1:373 Pancreatic cancer 2:102 Pandhara rassa 1:540 Pan-fried meat-based dishes Japanese 1:544 Korean see under Korea Panfrying 1:373 Pantothenic acid 2:128 Papain 3:441 Paper as foreign body in meat 2:23, 2:23T spices adhered to 1:305 Paper electrophoresis, fish assessment freshness, K value measurement 2:11, 2:11F, 2:12F safety, histamine determination 2:14, 2:14F Parasites finfish 3:342 meat and viscera, land-farmed animals 3:34–41

523

detection at slaughter, new approaches 3:40–41 drivers for transmission among farmed animals and to humans 3:41 eating habits 3:41 farming system 3:41 ecological patterns of transmission and maintenance of life cycle 3:34 farmed animals as intermediate hosts 3:34–39 equine species 3:40 farmed lagomorphs 3:40 farmed ruminants 3:34–39 farmed swine 3:39–40 poultry 3:40 goats see Goat(s) main species 3:35–38T public health impact of zoonotic meatborne parasites from domestic animals 3:41 Parathyroid hormone, bone growth and 2:80–81 Parma ham definition 2:87 presentation 2:88 salting 2:89 drying-maturation and cellar phase 2:90 ingredients and additives 2:89 resting period 2:90 washing 2:89 see also Dry-cured ham production Partial pressure, definition 3:388 Particle reduction equipment bowl choppers see Bowl choppers emulsion mills 3:130 flaking equipment 3:130 mincers/grinders see Mincers/grinders see also Cutting equipment Partitioning agents, beta-adrenergic agonists 2:67 Parturition definition 2:190 difficulties, cloned pregnancies 1:88 Pascal (pa), definition 3:26 Pasta, extrusion technology 1:564–565 Pasteurization 1:385, 1:386 definition 1:385, 2:140, 2:236, 2:280, 3:184 in-package and during packaging, processed meat 2:281, 2:291 irradiation vs. 2:141 steam see Steam pasteurization Yersinia enterocolitica control 2:410 see also Cooking Pasting, leather drying 1:122 Pastoralism cattle production 2:214 definition 2:211 sheep and goat production 2:215 Pastrami definition 1:553 Middle Eastern 1:553 Pastures, carrying capacity, factors affecting 2:477, 2:477T Pate´ de foie gras 2:192 definition 2:190

524

Index

Patent application, preparation 3:48 Patenting 3:42–49 examples of patents see Patents, examples of how to prepare a patent application 3:48 legal requirements for patentability of inventions 3:42 in meat technology field 3:44–45 activity in different areas of meat technology 3:45, 3:46F meat preservation processes 3:44 meat processing 3:44 meat products 3:45 slaughter processes 3:44 trends 3:44F, 3:45F patent protection as exclusive right 3:42–43 patents as source of information 3:44 patents subsequent to publication 3:48 opposition 3:48 patent strategy 3:43–44 example 3:43, 3:43F process 3:43 Patents, examples of 3:45 apparatus 3:47 for antimicrobial treatment 3:48 cutter for splitting animals 3:47–48 for evisceration 3:47 guide wheels 3:48 markings for identification 3:48 sausage-cutting machine 3:48 patented products 3:45 composition for meat 3:45–47 fat-free meat product 3:45 low-fat meat product 3:45 pizza topping 3:45 processes/methods 3:47 ham production 3:47 prefermentation of meat 3:47 preserving meat by microorganisms 3:47 preserving meat by salts 3:47 preserving meat by with high pressure 3:47 processes for classification of meat 3:47 sausage production 3:47 product use 3:48 Paternoster lift 1:44 definition 1:43 Pate´s 1:529, 3:245, 3:258, 3:260 Pathogen(s) definition 2:306, 2:405, 3:295 destruction, use of indicator organisms to determine adequacy of processes 2:303–304 meat contamination indicator tests 2:286 see also Meatborne pathogens see also individual pathogens Pathogenic bacteria irradiation effects 2:143 see also specific pathogenic bacteria Pathogenic Escherichia coli (PEC) 2:357–361 control methods 2:360 during primary processing 2:360 detection 2:311, 2:359–360

ecology 2:359 enrichment protocol 2:311, 2:313–314T, 2:315T enumeration 2:311, 2:312T gastroenteritis 2:357, 2:357T immunocapture 2:359–360 isolation 2:359–360 meat, presence/survival on 2:359 new types 2:358 pathogenicity, molecular aspects 2:358–359 plating procedures 2:313–314T pre-enrichment protocol 2:311, 2:313–314T, 2:315T transmission 2:358 see also Escherichia coli; individual species Pathogenicity island, definition 2:357 Pathogenic microorganisms definition 2:289 see also Pathogen(s) Pathological lesions, food safety implications and detection 2:22, 2:22T ‘Patterning’ of the carcasses, cattle hind removal 3:286 Pauly reagent 2:14 definition 2:8 PAX3, myogenic differentiation 2:50 Payleans 2:177, 2:178, 2:179–180 effects of feeding with 2:178–179, 2:179F PCBs see Polychlorinated biphenyls (PCBs) PCR see Polymerase chain reaction (PCR) PCR-random amplified polymorphic deoxyribonucleic acid (PCR-RAPD), meat species identification 2:267–269, 2:268T PCR-restriction fragment length polymorphism (PCR-RFLP), meat species identification 2:267, 2:268T PCR-sequencing, meat species identification 2:267, 2:268T Pea proteins, use in comminuted meat products 1:294 Pearson correlation (r), definition 2:37 Peelable films 3:10 definition 3:9 Peelable packaging 3:10 Pekin ducks 3:372 Pelt removal definition 3:309 see also Sheep pelts Pemmican 1:555 Penicillium 2:395, 2:397F in meat 2:401 Pentastomids 3:35–38T 2-Pentylpyridine, formation via lipid–Maillard interactions 1:399, 1:400F Pepsin 1:301 Peptidases, definition 3:248 Peptide bond 1:237–238, 1:238F Peptone-iron agar (PIA), Shewanella putrefaciens enumeration 2:308T, 2:309 Percentage reflectance, color measurement 2:169–170, 2:170F

Percussion/percussive stunning 3:413 farmed fish 3:422, 3:423F see also Mechanical stunning Perferrylmyoglobin 3:398 definition 3:394 Performance Criterion (PC) 3:233 Performance Objective (PO) 3:232–233 definition 3:226 Perilipins, phosphorylation 2:47 Perimysium 1:149–150, 1:154F collagen fibers 1:322–323, 1:322F definition 1:252 myofiber adhesion 1:325 organization and meat quality 1:325 postmortem changes 1:325 structure 1:322–323, 1:323F thickness, muscle types 1:324–325 Periparturient, definition 3:102 Periwinkles 3:385 Permeability definition 3:26 packages see Packages, permeability Perna canaliculus (greenshell mussel) 3:384 Peroxisome proliferator activated receptor a (PPARa), adipogenesis 2:51 Peroxisome proliferator activated receptor g (PPARg) brown adipose tissue development 2:44 white adipose tissue development 2:44–45 Peroxisome proliferator activated receptor g coactivator 1-a (PGG1a), brown adipose tissue development 2:44 Peroxyacetic acid, carcass decontamination 2:278 Persistent organic pollutants (POPs) 1:497 Personal hygiene campylobacteriosis prevention 2:387 staphylococcal food poisoning prevention 2:380 Personnel requirements, laboratory accreditation 2:149 Pescatarians 2:135 Pesticides 1:497–498 environmental impacts 1:506 residues 3:219 toxaphene 1:497–498 Petechial hemorrhage (blood splash) causes 1:563 definition 1:366 minimization, by sticking/bleeding 3:298 Petroff–Hauser counting chamber 2:397 Pfa¨lzer Leberwurst 1:536 definition 1:530 Pfa¨lzer Saumagen 1:535 definition 1:530 Pfefferwurst 3:245 pH buffers see pH buffers changes during muscle–meat conversion 1:262, 1:263F, 3:365–366, 3:432, 3:432F importance of 1:263 measurements, time of 1:263–264 definition 1:262, 2:489 D, definition 1:486

Index

measurement, meat 1:264–265, 2:492–493 calibration 1:265–266 measurement conditions 1:265 temperature 1:265, 1:265F principal methods 1:264–265, 1:264F, 2:492–493 meat 1:262 buffers 1:262–263 Clostridium botulinum control in meats 2:333 effect of phosphates 1:299 effect on dry-cured ham production 2:88 effect on tenderness 1:334, 1:334F, 1:335–336, 1:335F measurement see pH, measurement, meat water-holding capacity and 1:257, 1:257F, 1:275–277, 1:277F muscle, postmortem effect of electrical stimulation 1:487, 1:488F see also dpH/dt; Electrical stimulation (ES), factors influencing effectiveness of effect on time of onset of rigor mortis 1:360, 1:361T glycogen debranching enzyme activity and 1:354 sausage metabolism and, fermented sausages 2:3–4 ultimate see Ultimate pH (pHu) Phacochoerus africanus see Warthog (Phacochoerus africanus) Phage see Bacteriophage(s) Phage typing Listeria monocytogenes 2:350 Salmonella 2:369, 2:369F Staphylococcus aureus 2:379 Pham’s model, freezing time 2:439 Phase contrast, definition 2:22 pH buffers definition 1:262 meat 1:262–263 Pheasants 3:373 Phenethanolamines see Beta-adrenergic agonists (BAA) Phenols, smoke see Smoke phenols Phenotype, definition 2:405 Phosphates 1:8, 1:299, 1:420, 1:444, 3:81 bacon curing solutions 1:56 effect on protein functionality protein solubility 1:269 water binding 1:268, 1:268F effect on water-holding capacity 1:278–279, 1:299 meat batter viscosity 1:299 meat pH and 1:299 see also Alkaline phosphates Phospholipid(s) 1:206, 1:239, 1:241, 3:394–395 definition 1:252, 2:111 in meat 2:114 oxidation 1:259–260

species-specific flavor 1:259 structure 1:241 Phosphorus 1:502 environmental impacts 1:504 in manure see Manure nutrients Phosphorus-31 nuclear magnetic resonance, fish freshness assessment 2:11 Phosphorus requirements, poultry 2:464T, 2:465 Photosynthesis 1:353 Photovoltaics, refrigeration for transport of meat 2:238 Phycomycetes 2:395 Phylogenetic, definition 2:348 Physical activity, muscle fiber type affected by 2:445 Physical entrapment theory 1:285 Physical measurements air velocity see Anemometers humidity see Humidity measurement product moisture content see Moisture content, measurement temperature see Temperature measurements water activity see Water activity, measurement Physical risk assessment 3:229 Physiochemical analysis methods see Chemical analysis methods Physiology, growth see Growth physiology Picking, definition 3:303 Pickle(s), meat see Meat pickles Pickle cure see Brine Pickle curing 1:421, 1:421T bacon 1:55–56 definition 1:416 see also Brine curing Pickle injection 1:421 see also Brine injectors Pickling 3:81 hides 1:120 Picnic cooked sausage production 3:241–242 definition 3:241 Piedmontese cattle, double muscling genetics 1:465–466 see also Double-muscled animals; Double muscling Pie´train pigs 1:466 Pig(s) 3:363–368 animal welfare 3:170–171 animal evaluation 3:171 body condition score 3:171 daily observation 3:171 effect of poor handling on 3:104T EU legislation for intensive breeding systems 2:217 herding instinct 3:172 lesions 3:171 pig performance 3:171 proper handling 3:171 recordkeeping 3:170–171 transport 3:172 treatment records 3:170–171 visual appraisal 3:171 antibiotic growth promotants 2:186

525

efficacy 2:172–173, 2:173F managing without 2:176 Asian breeds 3:360 for bacon 1:58 behavior during handling and transport see Animal behavior, during handling and transport bellies see Pork bellies bioactive peptides released during beef digestion 2:119, 2:120T bovine spongiform encephalopathy and 2:364 bruises 3:171 carcasses see Pig carcass(es) conjugated linoleic acid-fed 1:229 crossbreeding 1:20, 1:21F digestion and fermentation 3:357 disease control 2:186–189 domestication 3:359–360 dressing percentage 3:365 edible by-products intestines 1:110, 3:235–236, 3:236F pigs’ feet (’trotters’) 1:109–110 pig tail 1:109 pork jowl 1:109 pork skins 1:110 yield 1:105T European breeds 3:360 feed withdrawal, before slaughter 3:296–297 feet (’trotters’) 1:109–110 finishing Payleans feeding 2:178 effects 2:178–179, 2:179F see also Pig nutrition flight zone 3:86, 3:171–172 genetically engineered animals 1:94 genetic improvement programs, use of imaging techniques 1:23 growth 3:363–364 hair, rendering 1:128 herding instinct 3:172 intestines, as sausage casings 1:110, 3:235–236, 3:236F intramuscular fat distribution see under Intramuscular fat lairage see Lairage/lairaging lipid retention 2:455–456 listeriosis 2:351 male castrates vs. boars, pork production 1:97–98, 3:363 entire, carcass composition 3:363–364 see also Barrows; Boar(s) meat see Pork muscle hypertrophy 1:466 muscles, structural organization 1:324–325, 1:325F numbers/geographical distribution 2:212T, 2:213T, 2:216, 2:216–217 effect of religious factors 2:211, 2:216 nutrition see Pig nutrition on-farm quality assurance systems 3:295–296 over-conditioned, welfare issues 3:171 point of balance 3:97F

526

Index

Pig(s) (continued) postmortem muscle pH changes 1:339, 1:339F production systems see Pork production protein retention 2:455–456, 2:456F Salmonella monitoring/incidence 2:370T, 2:372 surveillance systems 2:221 slaughter see Pig slaughter/slaughter-line operation Streptococcus suis disease 2:342–343 transfer from farm to abattoir 1:366 on-farm handling and loading 1:366–367 transportation see Transport, pigs vaccination programs 2:186, 2:187 vision 3:85, 3:96–97, 3:98F vocalization, stress and 3:85, 3:100 weaning 2:455 whole-body protein mass 2:455 lipid mass and 2:455F, 2:456, 2:459 protein retention and 2:456, 2:456F as Yersinia enterocolitica source 2:410 see also entries beginning porcine; Pork Pig carcass(es) black scraping, carcass brushing, white scraping, and polishing 3:299–300 chilling 1:145, 1:146–147, 3:302 regime, effects on meat quality 1:369, 1:369T spray chilling 1:147 composition 1:149F, 1:149T, 3:363–364 differences among breeds 1:19–20 fat, distribution 1:152, 1:154F, 1:155F see also Carcass composition cutting/boning 1:461 automation see Cutting and boning, automation belly removal 1:462 general process 1:461–462 leg (fresh ham) 1:461, 1:462 loin 1:462 loin/ham break location 1:461 semihot boning 1:142–144, 1:144T shoulder 1:462 wholesale cuts 1:461, 1:462F dehairing 1:114, 3:299 dehiding 1:114, 1:368–369, 3:298 dressing effects on meat quality 1:368–369 percentage 3:365 electrical stimulation 1:146–147 fat distribution 1:152, 1:154F, 1:155F influence of nutrition 2:457 final wash 3:301 gambrelling 3:299 grading, weighing, and stamping 3:301 head removal 3:301 hot boning 1:455–456 lean meat yield estimation 3:300 quality, porcine somatotropin and 2:182–183 scalding 1:368–369, 1:389–390, 3:298–299 singeing 1:390, 3:299

splitting 3:300–301 thermal treatments 3:301–302 see also Pig slaughter/slaughter-line operation Pig carcass classification, Europe 1:316–320, 3:364–365 intermediate methods 1:318 online instruments 1:318 accuracy 1:319 authorization of prediction formula 1:319 calibration 1:319 invasive/back measurement methods (probe instruments) 1:318, 1:319F manual/automatic 1:319 noninvasive/back measurement methods 1:318–319 noninvasive/split-line methods 1:318 sampling 1:319 reference methods 1:316 accuracy 1:317, 1:317F alternative 1:317–318 computed tomography 1:317–318, 1:318F instrument calibration 1:316–317 subjective assessments 1:316 Pig carcass classification, US 3:364–365, 3:364F Pigeons, production systems 2:192 Pig farms Salmonella control and preventive measures 2:373T, 2:374, 3:296 transfer of animals to abattoirs see Pig(s), transfer from farm to abattoir see also Pork production Piglets, Clostridium difficile infection 2:341 Pigments 1:244–251 in cooked meats 1:248–249, 1:249T pink color defect 1:249–250 premature browning 1:249 in cured meats 1:250, 1:250T in fresh meat 1:245–248, 1:247T acid ferrimyoglobin peroxide 1:247T, 1:248 cytochrome c 1:247T, 1:248 ferrimyoglobin peroxide 1:247T, 1:248 ferrocholemyoglobin 1:248 isobetic points 2:169–170 myoglobin redox forms in packaged fresh meats 1:246–248, 1:246F, 1:247T sulfmyoglobin 1:247T, 1:248 meat pigment chemistry 3:14 oxidation 3:394, 3:397–398 see also Deoxymyoglobin; Meat color; Metmyoglobin; Myoglobin; Oxymyoglobin Pigment stabilization, nitrite 1:7–8 Pig nutrition 2:455–462 dietary amino acids in pig feeds 2:458–459, 2:459T dietary energy in pig foods 2:458 diet ingredients 2:459, 2:460T energy requirement 2:459–461, 2:461T food intake 2:457, 2:457F porcine somatotropin (pST) and 2:182

influence on eating quality of pig meat 2:457–458 minerals and vitamins requirement 2:459, 2:460T protein requirement 2:461 response to nutrient supply 2:456–457 retention of protein and lipid in pigs 2:455–456, 2:456F water requirement 2:459 see also Pig(s), finishing Pig production systems see Pork production Pigskin by-products 1:113T curing 1:115 dehairing 1:117–118 mechanical pulling (dehiding) 1:115, 1:368–369, 3:298 removal 1:114 uses 1:114 Pig slaughterhouses Salmonella contamination 2:372 stun box and restrainer design 3:90–91 transport to see Pig(s), transfer from farm to abattoir see also Lairage/lairaging, pigs Pig slaughter/slaughter-line operation 1:366, 1:367–368, 3:295–302 animal transport, receiving, and antemortem inspection 3:297 see also Transport of animals automation see Slaughter-line operation, automation black scraping, carcass brushing, white scraping, and polishing 3:299–300 carcass grading, weighing, and stamping 3:301 carcass splitting 3:300–301 chilling 3:302 dehairing 1:114, 3:299 dehiding 1:114, 1:368–369, 3:298 description of current slaughter practices 3:295, 3:296F effect of operations on meat quality see under Pork evisceration see Evisceration, pigs exsanguination 1:368 feed withdrawal 3:296–297 final trim 3:301 final wash 3:301 fin cutting 3:300 gambrelling 3:299 head removal 3:301 holding 3:297 see also Lairage/lairaging leaf fat removal and exposure of kidneys 3:301 lean meat yield estimation 3:300 on-farm pig quality assurance systems 3:295–296 preevisceration wash 3:300 scalding 1:368–369, 1:389–390, 3:298–299 shackling 3:297–298 singeing 1:390, 3:299 spinal cord removal 3:301 sticking and bleeding 3:298

Index

stunning 3:297–298 effects on meat quality 1:368, 1:368T electrical stunning 3:298, 3:411, 3:411F gas stunning 1:368, 3:297–298, 3:401 see also Gas stunning thermal treatments 3:301–302 weighing and recording 3:297 see also Pig carcass(es) Pig tail 1:109 Pili, biofilm formation role 1:67 Pilot tubes 3:54, 3:54F Pink color defect (PCD) 1:249–250 Pinking 3:137 Pish pash 1:541 definition 1:538 Pit curing, hides 1:116, 1:121T Pi-Vac Elasto-Pack Systems 1:454, 3:5, 3:5F, 3:31, 3:446, 3:446F Pizza toppings 3:246 patenting 3:45 Placenta, abnormalities, cloned pregnancies 1:87–88 Placental growth factors 2:51–52 Placental growth hormone (PGH) 2:51 Placental lactogen (PL), fetal growth 2:51 Planimeter, leather area measurement 1:123 Plank’s model, freezing process 2:439, 2:439F Planktonic cells biofilms vs., equipment cleaning 1:513 definition 1:64, 1:508 transport to surfaces and adhesion, biofilm formation 1:64–67, 1:65T Plant-derived ingredients, nitrate 1:8, 1:432–433 Plant enzymes, meat tenderization role 3:438, 3:441 Plant extracts, processed meat decontamination 2:283 Plant proteins see Nonmeat proteins Plant sterols, nutritional enhancement of meat products 2:453 Plasma proteins 1:292 Plasmid, definition 2:335, 2:340, 2:357 Plastic, as foreign body in meat 2:23, 2:23T Plastic casings, sausages 3:239 Plastic pouches, heat processing and 1:386 Plate count agar (PCA), spoilage bacteria 2:307–308, 2:308T Plate freezing 3:181–182, 3:200 definition 3:178 systems 3:186, 3:186F Platinum resistance thermometer, definition 3:57 PLC-control, definition 1:33 Pleistocene, definition 3:357 Pluck removal pigs 3:300 see also Evisceration Pluripotent, definition 1:83, 1:84 Pneumatic stunners 3:415, 3:415F Pneumonia, swine, pork quality 3:170 Poikilothermic, definition 2:190 Point of balance 3:86, 3:97 definition 3:84 pigs 3:97F

Point of sale, visual impact 3:268 Poland 1:558–560 meat products 1:558–559 canned meat 1:558 meat specialities 1:558, 1:559 definition 1:558 sausages 1:558, 1:559, 1:559F see also Polish sausage (Polska Kielbasa) smoked meats 1:558 meat research institutions national 2:255–256T provincial 2:257–261T Polarography 1:175 Polar overdominance, callipyge gene inheritance 1:344 Policy issues see Meat production business and public policy Polisher (dehairing machine) 1:114, 1:117–118 Polish sausage (Polska Kielbasa) 3:245, 3:264 additives/seasonings 3:263T finished form 3:265T processing 3:265T Political factors, animal production 2:211–212 Polska Kielbasa see Polish sausage (Polska Kielbasa) Polyacrylamide gel electrophoresis (PAGE), meat species determination 2:266 Polyamines definition 3:221 natural 3:221 Polyarthritis, definition 2:340 Polychlorinated biphenyls (PCBs) 1:498 concentrations in meat and fish 1:499 legislation 1:498–499 tolerable intake 1:498 Polycyclic aromatic hydrocarbons (PAHs) 3:223 definition 2:100, 3:221, 3:315 formation, strategies to reduce 3:223 health hazards associated with 3:67, 3:324 in processed meat 2:101 smoke condensates 3:317 wood smoke 3:223, 3:322, 3:324 Polyesters, packaging film chemistry 3:21 Polyethylenes, packaging film chemistry 3:21 Polylactic acid (PLA), definition 3:427 Polymer(s) chemistry, packaging films 3:21 definition 3:19 Polymerase chain reaction (PCR) definition 2:265, 2:285, 2:335 endpoint semiquantitative see Endpoint semiquantitative polymerase chain reaction Listeria monocytogenes detection 2:350 melt curve 2:295–296 definition 2:294 primer, definition 2:294 real-time see Real-time polymerase chain reaction template, definition 2:294

527

thermal cycling 2:294 definition 2:294 Polymerase chain reaction-based detection, foodborne pathogens 2:294–295 Aeromonas 2:321, 2:322T Clostridium perfringens 2:336–337 conventional PCR 2:294–295, 2:295F Listeria monocytogenes 2:350 multiplex PCR 2:295 real-time PCR 2:295–296 Salmonella 2:368 Staphylococcus aureus 2:379 Polymerase chain reaction-based methods, meat species determination 2:265, 2:266–267, 2:268T PCR-random amplified polymorphic deoxyribonucleic acid 2:267–269, 2:268T PCR-restriction fragment length polymorphism 2:267, 2:268T PCR-sequencing 2:267, 2:268T PCR with species-specific primers 2:267, 2:268T real-time PCR 2:268T, 2:269 Polymerase chain reaction-based subtyping, foodborne pathogens 2:297 Polyphosphates 1:8, 1:420, 1:444 Polypropylenes, packaging film chemistry 3:22 Polystyrene, packaging film chemistry 3:22 Polysulfur heterocyclics, formation via Maillard reaction 1:397, 1:398F Polyunsaturated fatty acids (PUFAs) 1:239–240, 2:121–122, 3:394–395 fish oils 1:132T, 1:133 human diet 2:121–122 kangaroo meat 3:352 leaner carcass production in poultry and 2:469 meat content 2:107, 2:114 domestication of animals and 3:361 melting point characteristics 1:240T n-3 definition 2:111 see also Omega-3 fatty acids n-6 definition 2:111 see also Omega-6 fatty acids nutritional enhancement of meat 2:452 oxidation 3:394–395, 3:395, 3:395F prevention 3:396 warmed-over flavor and 3:396 oxidative stress 1:410–411 pig meat, influence of nutrition 2:457–458 Polyvinyl chloride (PVC), packaging film chemistry 3:21 Polyvinylidene chloride (Saran), packaging film chemistry 3:21 Pon haus (scrapple) 1:556, 3:246 Porcine, definition 1:235 Porcine growth hormone (pGH) see Porcine somatotropin (pST) Porcine reproductive and respiratory syndrome (PRRS), specific pathogen free pig programs 2:188

528

Index

Porcine reproductive and respiratory syndrome virus (PRRSv) dose–response relationship 1:30 imported pig meat entry assessment 1:30F exposure assessment 1:30 high-risk tissue removal 1:31 inactivation treatments 1:31 infectious dose probability 1:30–31 risk management 1:31 stabilized herds 1:31 Porcine somatotropin (pST) 2:181–185 adipose tissue metabolism 2:183 amino acid requirements 2:183 animal health 2:183–184 average daily gain 2:182 carcass fat 2:183 carcass quality 2:182–183 cooking loss 2:184 dose-dependent responses 2:182, 2:183F feed intake changes 2:182 historical aspects 2:181 intramuscular fat 2:184 meat collagen content 2:184 meat color 2:184 meat juiciness 2:184 meat quality 2:184 meat tenderness 2:184, 2:184–185 meat toughness 2:184 muscle characteristics 2:184 muscle tissue increases 2:183 performance 2:182–183, 2:183F, 2:183T postmortem rate/extent 2:184 potential for growth and 2:183 routes of administration 2:181 shear force changes 2:184 Pork 2:215 aging 1:335 carcasses see Pig carcass(es) Clostridium botulinum contamination incidence 2:342 see also Clostridium botulinum Clostridium difficile contamination 2:341 Clostridium perfringens contamination 2:337–338 consumption per capita (US) 2:248, 2:249F dark, firm, and dry meat see Dark, firm, and dry (DFD) meat demand index (USA) 2:250, 2:251F drip loss 1:339–340 fat quality 3:367 fatty acid composition 2:116, 2:116T flavors, unacceptable 3:277T marbling to meat palatability relationship 1:254–256, 1:256T mechanically recovered composition 2:273, 2:273T uses 2:272 Mycobacterium avium subsp. paratuberculosis (MAP) contamination 2:342 nutrient composition 3:367, 3:371T pale, soft, exudative (PSE) meat see Pale, soft, and exudative (PSE) condition in meat

prices, US 2:248, 2:249F production see Pork production pulled 1:557 quality see Pork quality sensory assessment see Sensory assessment, meat shelf life, irradiation effects 2:143 Streptococcus suis contamination 2:343 tenderness 3:366 influence of nutrition 2:457 vacuum packaging 3:32 Yersinia enterocolitica contamination 2:410 see also Pig(s) Pork bellies 3:367 bacon preparation 1:446 belly bacon production 1:54–55 fat softness 1:55 frozen, bacon production 1:54–55 quality, animal diet and 1:54 removal from carcass 1:462 trimming specifications 1:54 trimming yield 1:54, 1:54F, 1:55F see also Belly bacon Pork dishes, French braised 1:528, 1:529F charcuterie see French meat products and dishes Pork jowl 1:109 Pork production 2:215–217, 3:363 advantages/disadvantages of using entire males 1:97–98 cultural factors 2:211 global 1:502, 1:502F indigenous, ranking 2:215T intensive indoor systems 2:216, 2:216F EU legislation 2:217 organic 2:200–201, 2:200F outdoor systems 2:216, 2:216F problems 2:216 see also Pig(s) Pork quality 3:365–367, 3:366F effect on dry-cured ham production 2:87–88 effects of slaughter-line operation 1:366–369 carcass dressing 1:368–369 chilling regime 1:369, 1:369T lairage period 1:367, 1:367T on-farm handling and loading 1:367 preslaughter stress 1:366, 3:268–269 stunning and exsanguination 1:368, 1:368T transportation 1:367 farm level 3:168–172 abnormal pH drop kinetics 1:339F, 1:340 animal welfare 3:170–171 assurance programs 3:168 barn management 3:169 biosecurity 3:170 bruises 3:171 definition 3:168 farm setup/design 3:169 feed/nutrition 3:169–170 genetics 3:169 over-conditioned pigs 3:171

postmortem muscle pH changes 1:339–340, 1:339F production factors affecting 3:169 proper animal handling 3:171 swine health 3:170 swine husbandry 3:169 improvement, application of genomic technologies 2:38–39 influence of nutrition 2:457–458 measurement fat softness 2:492 pale, soft, exudative and marbling 2:490–491 Pork Quality Assurances (PQA) 3:168–169 definition 3:168 Pork Quality Assurance (PQA) Pluss program 3:168–169 Good Production Practices 3:169, 3:169T site status 3:168–169 Pork sausage 3:261 fresh see Fresh sausage whole hog sausage 3:261 see also Sausage(s) Pork shoulder, cooked sausage production 3:241–242 Pork skins 1:110 Postmortem, definition 1:329, 1:486, 3:267 Postmortem changes muscle see Muscle muscle connective tissue see Connective tissue pH see pH, changes during muscle–meat conversion shear force, time course changes 1:363, 1:363F, 3:443, 3:444F Postmortem glycolysis rate, effect on waterholding capacity 1:278 Postnatal development, muscle see Muscle development, postnatal Postnatal growth anti-insulin effects 2:52 endocrinology 2:52 see also Growth Postprandial, definition 2:75 Postrigor changes, near infrared (NIR) spectroscopy 3:72–73, 3:73–76, 3:74F, 3:75F Postslaughter considerations, immobilization 3:419–420 Postslaughter management, effects on carcass quality, small ruminants 3:378 Potamochoerus larvatus (bushpig) 3:352 Potassium in manure 2:153 requirements, poultry 2:464T, 2:465–466 Potassium chloride as curing ingredient 1:418 see also Salt Potassium lactate 1:298–299 Potassium nitrate see Saltpeter (potassium nitrate) Potassium nitrite 1:298 Potassium phosphates 1:299 Potassium sorbate Bacillus cereus control 2:328

Index

Staphylococcus aureus control 2:380 Yersinia enterocolitica control 2:410 Potentiometry 1:174–175 Poultry 3:369–373 Aeromonas occurrence 2:318 campylobacteriosis association, control measures in meat processing plants 2:386 in poultry houses 2:386 definition 1:235, 2:463, 3:369 digestive tract 2:463 domestication 3:360 feet as edible by-product 1:110 removal 3:306 fungi in 2:402T global production 1:502, 1:502F growth rate increases 3:361 as intermediate hosts for parasites 3:40 listeriosis 2:351 metabolic diseases with increased growth rate 3:361 mitochondrial DNA 3:360 nutrition see Poultry nutrition origins 3:360 production systems see Chicken meat production systems Salmonella monitoring/incidence 2:370T, 2:372 slaughter see Poultry, slaughter-line operation USA consumption by year 2:250, 2:252F see also individual species Poultry, slaughter-line operation 3:303–308 bleeding 3:305 carcass chilling 3:307–308, 3:307F definition 3:303 carcass prechilling 3:308 definition 3:303 electrical stimulation 3:306 evisceration 3:306 feather removal 3:306, 3:306F feet removal 3:306 giblet salvage 3:307 grading, weighing, and packaging 3:308 immobilization 3:418 inside/outside bird wash 3:307 inspection 3:306–307 lung, head, and crop removal 3:307 picking, definition 3:303 receiving and weighing 3:303 rehanging 3:306 scalding see Scalding steps 3:303, 3:304F stunning see Stunning, poultry unloading 3:303 see also Poultry carcasses Poultry carcasses chilling 1:147, 3:307–308, 3:307F definition 3:303 chilling, primary 3:185 air 3:185, 3:185F immersion 3:185, 3:186F spray/evaporative chilling 3:185

downgrading, nutrition and 2:469 electrical stimulation 3:306 finish, nutrition and 2:469 hot boning 1:456–457 rehanging 3:306 scalding see Scalding see also Poultry, slaughter-line operation Poultry farmers, Aeromonas infection risk 2:320 Poultry farms Salmonella control and preventive measures 2:374 see also Chicken meat production systems Poultry fat 1:133 fatty acid composition 1:132T properties 1:131T Poultry feed formulations feed additives 2:466–468, 2:467T feeding programs 2:466–468 ingredients 2:466, 2:467T Poultry giblets, as edible by-product 1:111 Poultry houses, thermotolerant Campylobacter control 2:386 Poultry meal 1:134–135 Poultry meat aging 1:335 cooked, pink color defect 1:249–250 fat content 2:112 freezing, effect on product quality 3:194 meat acidification 1:340 mechanically recovered composition 2:272, 2:273T safety 2:274 uses 2:272 pale, soft, and exudative 1:145, 1:343, 3:370 quality improvement, application of genomic technologies 2:39 see also Chicken meat; Turkey meat Poultry nutrition 2:463–470 carcass quality and 2:469 feed formulations see Poultry feed formulations feeding for leaner carcass production 2:468 novel nutritional approaches 2:468 restriction of energy intake 2:468 nutrient requirements 2:463–465, 2:464T, 2:468 energy 2:463–465, 2:464T fats and fatty acids 2:464T, 2:465 minerals 2:464T, 2:465–466 protein and amino acids 2:464T, 2:465, 2:465T vitamins 2:464T, 2:466 water 2:466 Poultry slaughterhouses, Salmonella contamination 2:372 Poultry stalls, wet markets 2:244–245 Pour plate method, spoilage bacteria 2:307 Powered gates, in stockyards 3:93 Ppb (part per billion) 1:502 Prague powder 1:443 Prawn 3:380 blue 3:380F common edible species 3:382T

529

PRDM16 brown adipose tissue development 2:44 myoblasts 2:44 Preadipocytes 2:44–45 cell lines 2:45 differentiation 2:45, 2:46F Prebiotics definition 2:32 in meat products 2:35 Preblending, emulsions 3:256 salt in 1:296–297 Prebrine system, natural curing 1:431 Precision accuracy and 2:481, 2:481F definition 1:193, 1:194, 2:481 Precocial, definition 3:357 Precocial species, domestication of animals 3:357 Preconverted system, natural curing 1:431 Precooked bacon consumption 1:53 historical aspects 1:54 packaging 1:57 raw materials 1:54 slice thickness 1:57 Precooking, for chilled foods 3:206 Predictive microbiology, hurdle technology design 2:347 ‘Predikantsbiltong’ 1:515 Predust/predusting definition 3:116 equipment 3:116–117, 3:118F see also Battering/breading equipment Preevisceration washing cattle slaughter process 3:287 pig slaughter process 3:300 Prefermentation of meat, patenting 3:47 Preformed trays 3:6, 3:7F definition 3:2 Pregnant women, listeriosis 2:351 Premarketing authorization definition 3:214 veterinary medicinal products 3:215–216 Premature browning (PMB) 1:249 high-oxygen packaging and 3:10, 3:11 Premium hams 1:447 Prepathological state 3:106 Prerigor changes, near infrared (NIR) spectroscopy 3:72–73, 3:73, 3:74F, 3:75F Preservation methods 3:78–83 biltong 1:516 historical aspects 3:191 individual techniques utilized 3:78–79 additives 3:80 antioxidants 3:81 binders 3:81 biopreservation 3:82 canning 3:81 casings 3:81 color additives 3:81 drying see Drying freezing see Freezing high-pressure food preservation see High-pressure food preservation hurdle technology 3:82

530

Index

Preservation methods (continued) irradiation 3:81–82 pickling 3:81 pulsed electric fields processing 3:82 reducing compounds 3:80–81 refrigeration 3:79 salt 3:79–80, 3:79T smoking 3:80 spices 3:81 sweeteners 3:80 tenderization 3:81 vacuum and modified atmosphere packaging 3:79 patenting 3:44 see also Patents, examples of see also Biopreservation; specific methods Preservatives Bacillus cereus control 2:328 Clostridium botulinum control 2:333–334 cured meat products 1:301 natural curing 1:433 processed meats 2:291 see also Processed meat, decontamination salt-pack curing, hides 1:115 Staphylococcus aureus control 2:380 see also specific preservatives Preserved meats bacterial spoilage 3:392, 3:392T see also Cured meats; Processed meat(s) Preslaughter, definition 1:329, 1:486, 3:267 Preslaughter handling 3:95–101 definition 3:95 effects on meat quality 3:100–101 sensory aspects 3:268–269 see also Preslaughter stress, effect on meat quality lairaging at abattoirs 3:98–100, 3:99F see also Lairage/lairaging loading and unloading 3:96–97, 3:96F, 3:97F methods of measuring preslaughter stress 3:95 movement from lairage to stunning pen 3:100 preparation for transport 3:95–96 transportation 3:97–98, 3:98F see also Transport Preslaughter stress effect on meat aging 1:334, 1:335F effect on meat quality 1:350, 3:100–101 assessment of preslaughter stress and 3:95 glycogen content 1:350, 1:350F, 1:351F pork 1:366, 3:268–269 sensory aspects 3:268–269 meat color and 2:446 methods of measuring 3:95 see also Stress Press method, water-holding capacity measurement 2:166 Pressure measurements 3:27T units 3:26 Pressure-assisted thawing 3:207 Pressure cooking, rendering 1:127

Pressure flow 1:564 Prestuck casing, sausages 3:239 Price discovery 2:248–250 definition 2:248 Prices of meat see Meat pricing systems Pricing efficiency see under Meat pricing systems Prieta 1:520–521, 1:520F Primal, definition 1:458, 1:458–459 Primal cuts, definition 1:33, 3:13 Primal cutting, automatic bovine carcasses 1:36–37 porcine carcasses 1:34 Primer, polymerase chain reaction definition 2:294 see also Polymerase chain reaction (PCR) Principal component analysis (PCA), definition 2:1, 3:70 Prions 2:362–366 biochemical and physical properties 2:362–363 prion-infected brain tissue, spongiform damage see Transmissible spongiform encephalopathies (TSEs) rendering, effects on 1:129 Private industrial meat research institutions 2:262–263T PRKAG3 gene 1:341 definition 1:339 mutations 1:341 Probe instruments, pig carcass classification 1:318, 1:319F Probiotic bacteria definition 2:280 processed meat decontamination 2:282–283, 2:291 Probiotics definition 2:32 in meat products 2:35 Procambarus clarkia (red swamp crawfish) 3:381 Procambarus leniusculus (Pacific crayfish) 3:381 Procambarus zonangulu (white river crawfish) 3:381 Process, definition 3:295 Process control 3:160, 3:162F definition 3:159 Process description, hazard analysis and critical control point 2:95 Processed flavors 1:305 Processed meat(s) cancer and 2:101, 2:102, 2:103 clean label alternatives 2:282 decontamination see Processed meat, decontamination definition 2:289 extenders see Extenders functional ingredients see Functional ingredients, meat products human disease/cancer association 1:436 microbial contamination see Processed meat, microbial contamination quality, microbial contamination intervention and 2:291–292

recontamination, indicator organisms 2:304 salt level reduction 2:126 uncured, labeling see Uncured processed meats vacuum packaging 3:29, 3:30 see also Comminuted meat products; Cured meats; individual products; Meat products Processed meat, decontamination 2:280–284, 2:290–291 active packaging see Active packaging bacteriophage 2:283 chemical antimicrobials 2:282, 2:291 definition 2:280 clean label alternatives 2:282 combination therapy technology 2:291 see also Hurdle approach; Hurdle technology high-pressure processing 2:283–284, 2:291 definition 2:280 nonthermal technologies 2:281–282 irradiation 2:281–282, 2:290–291 plant extracts 2:283, 2:291 probiotic bacteria and bacteriocins 2:282–283, 2:291 processed meat quality and 2:291–292 thermal technologies 2:281 infrared heating 2:281 in-package and during packaging thermal pasteurization 2:281, 2:291 validation 2:284 see also Fresh meat, decontamination Processed meat, microbial contamination 2:289 examples of microbial contaminants 2:290 intervention against microbial contaminants 2:290–291 processed meat quality and 2:291–292 see also Processed meat, decontamination recontamination, indicator organisms 2:304 Shiga toxin-producing E. coli 2:359 sources 2:289–290 Processing carcinogens and mutagens after 2:101 characteristics, market specifications 2:233–234 crayfish 3:381 effect on sensory aspects of meat quality see Sensory aspects of meat quality, factors affecting/optimization of finfish 3:342 heat see Thermal processing optimization 3:428 patenting and 3:44 see also Patents, examples of plants quality management activities see Quality management activities/ systems thermotolerant Campylobacter control measures 2:386 protocols, effect on protein gelation 1:271 see also individual meats/products

Index

Processing control, dry-cured products 1:428–429 Processing environments, Listeria monocytogenes contamination 2:353, 2:353F Processing equipment battering and breading see Battering/ breading equipment biofilms and 1:68, 1:513 brine injectors see Brine injectors cleaning see Equipment cleaning cooking equipment see Cooking equipment hygienic design 1:511–512, 1:512F massagers see Massagers smoking equipment 3:140–141, 3:140F, 3:141F traditional smoking see under Smoking, traditional tumblers see Tumblers Processor, definition 3:295 Processors (manufacturers), meat pricing system 2:253 Product description, hazard analysis and critical control point 2:95 Product differentiation, market specifications and 2:232–233 Production diseases, animal welfare 3:104 Production systems exotic species 2:190–198 see also individual species influence on sensory aspects of meat quality 3:268 organic see Organic meat production poultry see Chicken meat production systems see also Meat production Product moisture content see Moisture content Product quality see Meat quality Product specifications, assessment of adherence to 2:234 see also Meat marketing, requirements/specification Product testing definition 3:159 quality assurance strategy in meat production chain 3:160, 3:162F Product use, patenting 3:48 Professional organizations 3:147–154 by country 3:149–153T international 3:148T Progeny testing 1:24–25 Progesterone, pubertal growth 2:53 Progestins, in animal production 2:62 Proglycogen 1:348 Programmable logic controller, definition 1:33 Pronuclear injection 1:92 definition 1:92 Prooxidant, iron as 2:121 Propyl gallate, warmed-over flavor prevention 1:413 Prosobranchia 3:385 Prostate cancer 2:103 Proteases

action during dry curing 1:425–426, 1:426F definition 1:252, 1:425 endogenous, definition 3:438 see also Tenderizing mechanisms, enzymatic Proteasomes, 20S, analysis in meats 1:216 Protected Designation of Origin (PDO) German meat products 1:531 Mediterranean meat products 1:551 Protected Geographical Indication (PGI) German meat products 1:531, 1:532T Mediterranean meat products 1:551 Protective functions, packages 3:19–20 Protein(s) analysis see Protein analysis methods animal-derived, inedible 1:133–134 daily requirement (human) 2:112–113 denaturation see Protein denaturation digestion rate 2:118, 2:119–120 formation 1:353 functionality see Muscle proteins, functionality human diet see under Nutrition (human) low-protein diet 2:109 meat see Meat protein(s) microbial, use in comminuted meat products 1:289T, 1:294 milk see Milk proteins nonmeat see Nonmeat proteins solubility see Protein solubility structure see Protein structure see also entries beginning protein Protein analysis methods 1:182T, 1:183–184, 1:209, 1:210F near infrared spectroscopy meat composition analysis 1:209 meat quality assessment 2:491 rapid methods 1:182T, 1:184 see also Amino acid(s), analysis Proteinase K, prion protein degradation 2:362–363 differential mobility of digestion products (western blot) 2:366F Protein-based methods, species determination see Species determination (meat species) Protein content factors affecting see Meat protein(s), factors influencing content in meat raw meat 1:180 analysis see Raw material composition analysis Protein denaturation actin 1:371 definition 1:252, 1:329, 1:370, 1:486 heat see Heat denaturation myoglobin see Myoglobin myosin see Myosin pork muscle 1:339–340 see also Heat denaturation Protein digestion, ruminants 2:472, 2:473F Protein extraction comminuted meat product processing 1:284 definition 3:256

531

Protein fibers, muscle connective tissue 1:149–150 see also Collagen; Elastin Protein kinase A (PKA), lipolysis 2:47 Protein metabolism, myostatin role 1:466 Protein oxidation 3:394, 3:398–399 warmed-over flavor 1:411 Protein–protein bind, mechanical conditioning 3:144 Protein requirements pigs 2:461 poultry 2:465 Protein retention, pigs 2:455–456, 2:456F Protein solubility 1:268–269 definition 1:267, 1:269 effect of ionic strength 1:269, 1:269F effect of muscle fiber type 1:269–270 effect of phosphates 1:269 protein structure and 1:269 water-holding capacity measurement 2:167 Protein structure 1:237–238, 1:238F protein solubility and 1:269 Protein tagging technology 1:182T, 1:184 Protein–water bind, internal, mechanical conditioning 3:144 Proteoglycans 1:242 definition 1:321 postmortem degradation of connective tissue 1:325, 1:326F thermal instability 1:326 Proteolysis 3:432 definition 1:425, 1:550, 3:248, 3:431, 3:443, 3:452 in dry curing see Dry curing meat aging 1:340 see also Tenderization Proteome definition 3:155 role in properties of muscle as food 3:155–156 Proteomics 1:13, 2:41, 3:155–158 applications in meat science and meat industry 2:41, 3:155 cattle industries 3:331 conversion of muscle to meat 3:156 dry-cured meats 3:157 meat color stability 3:157 meat tenderization 3:156–157 preharvest applications 3:156 definition 2:49, 3:155 tools 3:155 Protozoa, elimination see Ruminal defaunation Protozoans 3:35–38T see also Parasites Provincial meat research institutions 2:257–261T Proximate composition 1:180 analysis see Raw material composition analysis definition 1:180 PRT (platinum resistance thermometer), definition 3:57 PSE see Pale, soft, and exudative (PSE) condition in meat

532

Index

Pseudomonads enumeration media 2:308 meat spoilage, factors affecting 3:389, 3:389T, 3:392T Pseudomonas fluorescens, enumeration 2:308 Pseudomonas fragi, enumeration 2:308 Psychrometers 3:51 Psychrophiles, definition 2:285 Psychrotroph, definition 2:285, 2:405, 3:13 Psychrotrophic pathogens, vacuum packaging 3:31 Pubertal growth bone 2:80 endocrinology 2:53 female hormones 2:53 male hormones 2:53 modes of action 2:53 Public health hazards, wet markets 2:245–246 Public health impacts, zoonotic meatborne parasites from domestic animals 3:41 Public policy, meat production business and see Meat production business and public policy Pudding 3:246 Puerto Rico, provincial meat research institution 2:257–261T Puffer fish toxin, definition 2:8 Pulled pork 1:557 Pullman ham 1:448, 1:448T Pulsed electric fields (PEFs) processing 3:82 Pulsed field gel electrophoresis (PFGE) 2:297–298, 2:298F Listeria monocytogenes subtyping 2:350–351 Salmonella epidemiological/outbreak investigation 2:369, 2:369F Staphylococcus aureus typing 2:379 thermotolerant Campylobacter subspecies identification 2:383 Pulse waveforms see under Electrical stimulation (ES) Pump mincer/grinder 3:129 Pumps, brine injectors 3:124–125 Pure water, pressure–temperature phase diagram 1:475–476, 1:476F Purge definition 1:486 measurement 2:165 see also Drip Putrescine 3:221 in raw fermented sausages 3:222, 3:222T toxicological effects 3:222T PVC (polyvinyl chloride), packaging film chemistry 3:21 Pyrazines, formation via Maillard reaction 1:396, 1:396F Pyrolysis definition 1:410 rapid thermal see Rapid thermal pyrolysis Pyrophosphate 1:8 Pyruvate 1:353

Q Quahog clams 3:384F, 3:384T Quail 3:373 slaughter process 3:293–294 Qualitative methods, definition 2:306 Quality, meat see Meat quality Quality assurance analytical methods 1:178 definition 3:159 on-farm pig quality assurance systems 3:295–296 packaging film production/packaging 3:24 strategies in meat production chain 3:160, 3:162F process control 3:160, 3:162F product testing 3:160, 3:162F system control 3:160–163, 3:162F see also Quality management activities/ systems Quality control 3:160 definition 3:159 Quality management activities/systems 3:159–167 future prospects 3:165–166 quality attributes of meat and meat products 3:159–160, 3:161T quality management in meat production chain 3:165 activities 3:165, 3:166F aims 3:165 documentation 3:165 quality management tools 3:160, 3:162F standardized quality management and certification 3:163 certification process 3:163–164 historical development 3:163 management systems 3:163 special certification programs 3:164–165 see also Quality assurance Quality of extruded food 1:568–569 Quantitative descriptive analysis (QDA) 3:272–273 definition 3:272 Quantitative risk management 3:232 establishment of additional quantitative food safety targets 3:232–233 Performance Criterion 3:233 Performance Objective 3:232–233 definition 3:226 Food Safety Objective 3:232 definition 3:226 Quantitative trait, definition 1:12 Quantitative trait loci (QTL) 1:13 carcass and meat quality traits 1:13–14, 1:15T identification 1:14–17, 1:15T, 1:16F poultry 2:39 definition 1:12 domestication of animals and 3:361 online databases 1:13 Quaternary ammonium compounds (QACs) 3:67, 3:67F Bacillus cereus control 2:328 definition 3:64

Quick-dry slice (QDS) process 1:477–478, 1:477F, 2:90 definition 1:471, 2:87 traditional drying vs. 1:477–478, 1:477F Quorum sensing biofilm formation role 1:68 definition 1:64 Quorum-sensing molecules, in Aeromonas 2:320

R Rabbits 3:352–353 breeding programs 3:353 French dishes 1:528 as intermediate hosts for parasites 3:40 meat composition 3:353 production systems 2:195 slaughter process 3:293 electrical stunning 3:293, 3:411 Races definition 3:84 layout principles 3:91–92, 3:91F Raceway curing, hides 1:116, 1:119T, 1:120T Raceway vat 1:116 Ractopamine (ractopamine hydrochloride) 2:177, 2:178, 2:178F, 2:179–180 approval 2:66–67 carcass fat reduction 2:80 definition 2:62 growth promotion 2:53–54 meat tenderness and 2:68 muscle growth and 2:67 Radiant heating 1:388 Radiant heat sources 1:388, 1:388T Radiation (electromagnetic) definition 2:140 dose 2:141 energy spectrum 2:141, 2:141F gamma, definition 1:515 nonfood applications 2:140 see also Food irradiation; Ionizing radiation; Nonionizing radiation Radiation, definition 3:196 Radiation, thermal 3:197–198 definition 1:385, 2:236, 3:184 heating processes 3:198 Radioactive isotopes, meat composition measurement 2:485 Radiofrequency heating 1:388–389, 1:389 meat cooking 1:301 thawing method 3:207 Radionuclides see under Environmental contaminants Radura symbol 2:141 Rail boning, definition 1:33 Rainbow trout 3:340–341T nutritional content 3:336–342, 3:342T Ramps, unloading, design 3:93 Rancidity aldehydes and 3:395 fatty acid composition of meat 2:115–116 see also Warmed-over flavor (WOF) Rapid detection methods

Index

Listeria monocytogenes 2:350–351 Salmonella 2:368 Rapid filter paper method, water-holding capacity measurement 2:166, 2:167F Rapid thermal pyrolysis definition 3:315 smoke condensate production 3:315–316 Rapka 1:541 definition 1:538 Ratites 3:346, 3:346T, 3:372–373 definition 3:369 production systems 2:191 trends 3:372 Raw material(s) contaminated, indicator organisms in identification of 2:302–303 cooked ham production, selection and preparation 2:82–83 dry-cured ham production see under Drycured ham production fermented sausages 2:2 Raw material composition analysis 1:180–186 fat see Fat analysis methods moisture analysis methods 1:182T, 1:184 official methods 1:182T, 1:184 rapid methods 1:182T, 1:184 see also Moisture content, measurement multicomponent methods 1:182T, 1:184–185 guided microwave spectrometry 1:185 near-infrared method 1:185 nuclear magnetic resonance 1:185–186 performance of analytical methods 1:181 protein see Protein analysis methods see also Chemical analysis, major meat components; Chemical analysis, micronutrients and other minor meat components Raw meat aroma 1:258 Raw muscle tissue, aerobic spoilage, factors affecting 3:388–390, 3:389T Reactive arthritis, Yersinia enterocolitica infection-associated 2:407 Ready-to-eat (RTE) products/foods cooked sausages 3:243, 3:258 definition 2:17, 2:290, 3:241 Listeria monocytogenes contamination 2:280, 2:348 control measures 2:280–281, 2:354–356, 2:355T see also Processed meat, decontamination see also Listeriosis see also individual products; Processed meat(s) Reagents, laboratory accreditation requirements 2:149–150 Real-time polymerase chain reaction 2:295–296 meat species identification 2:268T, 2:269 Reciprocating compressor 3:200 Recombinant porcine growth factor, lean growth stimulation 2:52 Recommended dietary allowances 2:124 definition 2:124

Recontamination, processed products, indicator organisms 2:304 Recovery, definition 1:193, 1:194, 1:217 Rectal prolapse, swine 3:171 Recycling 2:157 animal by-products 2:161 Red deer 2:193 Caspian 2:194 meat 3:347–348, 3:350T stags, carcass fat 1:158–159, 1:164T see also Deer Red meat cancer association 2:101, 2:102 see also Cancer cardiovascular disease and 2:106 chilling systems 3:184–185 see also Chilling effect of freezing on product quality see Freezing, effect on product quality USA consumption by year 2:250, 2:252F see also individual red meats Red meat animals production systems 2:211–217 animal welfare and 2:212 cattle see Cattle production systems cultural factors 2:211 geographic conditions and 2:211, 2:212T goats see Goat production pigs see Pork production political factors 2:211–212 sheep see Sheep production vision 3:85, 3:96–97, 3:98F see also specific animals Redox potential Clostridium botulinum control in meats 2:333 definition 1:137, 2:345 Red swamp crawfish 3:381 Reduced aging 3:269 Reducing compounds 1:298, 3:80–81 definition 3:78 effects 1:298 forms 1:298 Reductants 1:298 Reductase, definition 3:394 Reduction, definition 3:2, 3:13, 3:19 Reference material, laboratory accreditation requirements 2:149–150 Reference method, definition 1:316 Refrigerants global warming potential 3:199–200 ideal 3:199 primary vs. secondary 3:201 secondary 3:201 Refrigerated raw material, frozen raw material vs., dry-cured ham production 2:88 Refrigerated storage, yeast growth 2:399 Refrigerated tumblers 3:145 Refrigeration 2:436, 3:79 application, definition 3:178 Bacillus cereus control 2:328 benefits 3:196 chilling of meat/meat products see Chilling Clostridium botulinum control 2:332–333

533

definition 1:385, 1:453, 2:225, 2:236, 3:178, 3:184, 3:196, 3:196 importance in cold chain 2:236 see also Chilling; Cold chain technology applications 3:178–183 designing 3:182 mathematical models 3:182 principles 3:196–201 see also Chilling transport of meat/meat products see Transport of meat/meat products Refrigeration equipment 3:184–190 basic refrigeration system 3:184, 3:184F primary chilling systems 3:184 poultry carcasses see Poultry carcasses red meat 3:184–185 secondary systems vs. 3:187 primary freezing equipment 3:185 air blast 3:185–186 plate freezing 3:186, 3:186F secondary equipment vs. 3:187 retail display 2:228–229, 3:189 chilled unwrapped 3:189, 3:190F chilled wrapped 3:189, 3:189F frozen wrapped 3:189, 3:189F secondary chilling and freezing systems 3:186–187 cryogenic 3:187–188 high pressure 3:188 primary systems vs. 3:187 spray 3:187 vacuum 3:187 storage 3:188 domestic 3:189–190 transportation 3:188 eutectic plates 2:238, 3:188 liquid nitrogen 2:238, 3:188–189 mechanical units 2:238, 3:188 see also Transport of meat/meat products Refrigeration plant models 2:436, 2:437F Refrigeration process models 2:436–441 development 2:436 meat product chilling and freezing heat loads 2:440–441 meat product chilling and freezing times 2:437–440, 2:438F, 2:439F model boundaries 2:436–437, 2:437F Refrigeration systems 3:179–181, 3:198 efficiency 3:199–200 primary 3:200 secondary 3:200–201 see also Refrigeration; Refrigeration equipment Refrigerators domestic 2:229, 3:190 see also Refrigeration equipment Regensburger, definition 1:530 Regulation (EC) No. 1774/2002, animal byproduct use 1:125 Regulations/regulatory issues additives, meat products 1:7, 1:200, 1:201T, 1:443 see also specific additives dioxins and polychlorinated biphenyls in food and animal feed 1:498–499

534

Index

Regulations/regulatory issues (continued) indicator organisms 2:304 manure management 2:153 nutraceuticals 2:130–131 see also European Union (EU); Legislation Rehanging, poultry carcasses 3:306 Reindeer meat 3:347–348, 3:350T production systems 2:194 slaughter process 3:292 Relative humidity 3:50, 3:50F decreasing, chilling of meat 2:226 definition 3:50, 3:50 Relative humidity measurements, cooking processes 3:136 Relative standard deviation (RSD) calculation 1:187 definition 1:187 Religion, Middle East see Middle East Religious ethics, animal slaughter/meat eating and 3:282 Religious slaughter 3:209–213 definition 3:418 ethics 3:282 future perspectives 3:213 halal see Halal slaughter kosher see Kosher slaughtering (shechita) restraint 3:211–212, 3:212F stunned vs. conscious slaughter 3:212–213 see also Slaughter Rellena 1:521 Rendement Napole gene 3:365–366 Rendered bacon fat 1:54 Rendering batch systems 1:128 continuous hydrolysis 1:128 cooking times 1:128 EU regulation 1:125 feathers 1:128 historical aspects 1:125 microorganisms in raw materials 1:128, 1:129T pig hair 1:128 preparation for 1:127 pressure cooking 1:127 prions 1:129 process 1:126, 1:127–128, 1:128F regulations 1:127 statutory requirements 1:128–129 time–temperature processes 1:129 Repartitioning agents, beta-adrenergic agonists 2:67 Repeatability, definition 1:193, 1:194, 2:480 Representativeness, definition 2:218 Reproducibility, definition 1:193, 1:194, 2:480 Reproduction, double-muscled animals 1:467–468, 1:467T Reptiles, production systems 2:196–197 Research institutions see Meat research institutions Residual feed intake, definition 3:328 Residual oxygen effects, low-oxygen packaging 3:10–11 Residues, feed/drug 3:214–220 feed residues 3:216–217

food chain and origin of chemical residues in meat 3:215, 3:215F mandatory residue testing 3:218–219, 3:219T see also National Residue Control Plans (NRCPs) residues of feed additives and veterinary drugs 3:217–218 drug residues and consumer risks 3:218 see also Veterinary drug residue(s) risk mitigation, risk management, and risk communication 3:219 terms of reference and definitions 3:215 definition of chemical residues 3:216 definition of feed 3:215 definition of feed/food safety 3:216 definition of meat 3:216 definition of risk assessment 3:216 exposure assessment 3:214, 3:216, 3:217F hazard characterization 3:216 hazard identification 3:216 risk characterization and risk assessment 3:216, 3:217F definition of veterinary drugs 3:215–216 Residues, meat production-associated 3:221–225 biogenic amines see Biogenic amines heterocyclic amines see Heterocyclic amines nitrosamines see Nitrosamines polycyclic aromatic hydrocarbons see Polycyclic aromatic hydrocarbons (PAHs) processing steps associated with occurrence of residues 3:221T residual additives 3:223 residues from cleaning agents and disinfectants 3:224 residues from wrapping and packaging materials 3:224 Resistance hygrometers 3:51 Resistance thermometers 3:59, 3:60F Resistant determinants, definition 3:173 Respiratory distress, severity of, gas stunning 3:403–404, 3:403F Restaurants, thermotolerant Campylobacter control 2:387 Resting period after cooking 1:374 dry-cured ham production 2:90 Restrainer design 3:90–91 Restraint definition 3:418 immobilization vs. 3:418 religious slaughter 3:211–212, 3:212F Restriction endonuclease analysis (REA), Listeria monocytogenes subtyping 2:350–351 Restriction fragment length polymorphism (RFLP) Aeromonas studies 2:321–322 Listeria monocytogenes subtyping 2:350–351 Restructured jerky 1:555–556 Retail cuts, definition 3:13 Retail display

acceptable duration, overwrapped packages 3:15 cold chain and 2:228–229 frozen products 2:229 refrigeration equipment see Refrigeration equipment Retailed meat Arcobacter butzleri contamination 2:340–341 Bacillus cereus contamination 2:328 Clostridium difficile contamination 2:341 Salmonella contamination 2:373 thermotolerant Campylobacter contamination 2:385, 2:385T control/prevention measures see under Thermotolerant Campylobacter see also specific types Retail losses see Shrink (retail losses) Retail meat supply chain 2:248 Retail outlets, thermotolerant Campylobacter control 2:386–387 Retail-ready products, pathogenic E. coli control methods 2:360 Rete mirabile, exsanguination 1:562 Reticulum, ruminants 2:471, 2:471F, 2:472F Retorting 1:385 see also Sterilization Retort pouch 3:24 Retrogradation, starch see Starch(es), retrogradation RGB color space 2:168 definition 2:164 Rhea(s) 3:372 meat 3:346, 3:346T slaughter process 3:292–293 Rheometer assessment of fish freshness 2:13 definition 2:8 Rhizopus 2:395, 2:396F Rhizopus nigricans 2:396F Ribbon blenders 3:127, 3:127F Rib eye, definition 1:307 Riboflavin see Vitamin B2 (riboflavin) Ribonucleic acid (RNA) detection, foodborne pathogens 2:296 interference definition 1:92 genetic engineering of animals 1:94 short hairpin (shRNA), definition 1:92 Ribotyping 2:298–299 Rickets 2:127 Riemerella anatipestifer, routes of infection 1:29 Rights animal see Animal rights definition 1:480 Rigor 1:360 definition 1:329, 1:329–330, 1:358, 1:486, 3:431, 3:443 effect on water-holding capacity 1:277–278 postrigor changes, near infrared (NIR) spectroscopy 3:72–73, 3:73–76, 3:74F, 3:75F Rigor bonding 3:432

Index

Rigor index, fish freshness assessment 2:11–13, 2:12F Rigor mortis 1:157, 1:330–331, 1:360–362, 1:361F abnormal types 1:361 electrically stimulated muscles 1:362, 1:362F frozen muscle 1:361–362 pale, soft, exudative (PSE) muscle 1:362 definition 1:329, 1:329–330, 3:267, 3:431, 3:443 electrical stimulation effects 1:362, 1:362F, 1:493 factors affecting adenosine triphosphate 1:362F, 1:363 temperature 1:360F, 1:361T, 1:362–363, 1:362F time of onset 1:360, 1:361T influences on tenderness 1:363, 1:363F on water-holding capacity 1:363–364, 1:364F sarcomere length 1:257 see also Cold shortening; Rigor shortening Rigor shortening 1:333, 1:360 cold shortening vs. 1:361 definition 1:329, 3:431 mechanisms 1:363 see also Rigor mortis Rillettes 1:529 Rind emulsions 3:258 Ring bologna 3:245, 3:259 Ripening, fermented sausages 2:2, 2:2–3 modeling 2:5T, 2:6–7, 2:6F Risk definition 1:27, 1:27, 2:218, 3:226, 3:295 hazards vs. 3:227 Risk analysis 3:226–234 definition 1:27, 3:226 hazard analysis vs. 3:227 purpose and role 3:226–227 see also Hazard analysis and critical control point (HACCP) Risk assessment 3:227 animal health import risk analysis 1:28–29 chemical hazards 3:228–229 commissioning of 3:230 consideration of results 3:230 definition 1:27, 1:28, 3:214, 3:216, 3:217F failure mode and effects analysis 2:97–98, 2:98T foreign bodies 2:23 microbiological 3:229 physical 3:229 policy 3:230 qualitative 1:27–28 quantitative 1:27–28 steps 3:227 see also Exposure assessment; Hazard characterization; Hazard identification; Risk characterization see also Risk management Risk-based surveillance definition 2:218 meatborne hazards 2:220, 2:221T

Risk characterization 3:228 definition 3:216, 3:217F see also Risk assessment Risk communication 3:233 animal health import risk analysis 1:31–32 definition 1:27 feed and drug residues 3:219 peer review 1:32 Risk management 3:229–230 animal health import risk analysis 1:31 definition 1:27, 1:31 feed and drug residues 3:219 HACCP see Hazard analysis and critical control point (HACCP) monitoring and reviewing implemented risk management 3:231–232 options assessment 3:230–231 equivalence 3:231 identification of available options 3:231, 3:231T selection of options 3:231 quantitative see Quantitative risk management risk evaluation 3:229–230 commissioning of risk assessments 3:230 consideration of results of risk assessment 3:230 risk assessment policy 3:230 risk profiling 3:229–230 target setting and appropriate level of protection 3:230 see also Risk assessment steps 3:229 Risk mitigation, feed and drug residues 3:219 Risk profiling 3:229–230 Rista 1:539 Ritual slaughter, definition 3:418 River buffalo 2:192 RNA see Ribonucleic acid (RNA) RN gene see PRKAG3 gene Roasting 1:372–373, 1:372F Robotic automation cutting and boning ovine carcasses 1:40–42, 1:41F porcine carcasses 1:36, 1:37F see also Cutting and boning, automation ovine slaughter-line operation 1:49–52, 1:50F, 1:51F see also Slaughter-line operation, automation Rodents, production systems 2:195–196 Rogan josh 1:539 Rogosa agar, lactic acid bacteria enumeration 2:308T, 2:309 Rosemary, warmed-over flavor prevention 1:413 Rosmanol, warmed-over flavor prevention 1:413 Rotary oven, definition 3:315 Rotating drum tumbler 3:144 Rotavirus 2:393 disease 2:393 survival in food 2:393–394

535

virus characteristics 2:393 zoonotic transmission 2:393 Roter Schwartenmagen, definition 1:530 Rubber as foreign body in meat 2:23, 2:23T as surface in food production environments/equipment 1:509T Ru¨genwalder Teewurst 1:534 definition 1:530 production process 1:534, 1:534F Ruggedness, definition 1:217 Rumen 2:471, 2:471–472, 2:471F, 2:472F feed fermentation 2:471–472 see also Ruminants, feed/feeding microbial organisms 2:471–472, 2:473T Ruminal defaunation definition 1:71 effect on methane production in ruminants 1:73 Ruminants 2:471–479 anatomical distinction 2:471–472, 2:471F, 2:472F bloat 2:478–479 definition 2:111, 2:152, 2:471 electrical stunning 3:410–411 fatty acid composition of meat 2:115–116 as intermediate hosts for parasites 3:34–39 meat-producing, classes 2:475–477 see also Beef production; Goat production; Sheep production methane production see Biomethane production and cleanup small see Small ruminants see also Cattle; Deer; Goat(s); Sheep Ruminants, feed/feeding effect of diet components on methane production 1:73 feed digestion 2:472–475, 2:473F carbohydrates 2:474, 2:474F, 2:474T fat 2:472–473, 2:473F proteins 2:472, 2:473F general aspects of feeding 2:478–479 influence of feeds on manure nutrients 2:154 Rumination 2:472, 2:474–475 Rut, definition 2:190

S Saccharomyces cerevisiae, fermented foods 2:402 Safety electrical stimulation 1:490 feeding beta-agonists to meat animals 2:179–180 food see Food safety mechanically recovered meat (MRM) 2:274 mechanical stunning 3:415, 3:416F microbiological see Microbiological safety see also specific safety issues Safety assessment, fish see Fish inspection Safety factor (SF) 3:228 definition 3:226

536

Index

Safety implications, natural curing 1:434 Sainsbury’s, refrigeration of meat/meat products 2:238 Salami 1:551, 1:553 GreuXener see GreuXener salami Salbutamol 2:178, 2:178F Salchicha de huacho 1:520 Salchicho´n 1:551 Salinomycin as antibiotic growth promotants 2:175 small intestine microbial activity changes 2:173 Salivary glands, human, nitrate/nitrite concentrations 1:438, 1:439F Salmon, Atlantic 3:340–341T nutritional content 3:336–342, 3:342T Salmonella 2:18, 2:367–375 in animal feed 2:371–372 antimicrobial resistance 2:413–414 role of wild birds in transmission 2:420 characteristics 2:367–368 control and preventive measures 2:373–374 on farms 2:373–374 cattle farms 2:374 pig farms 2:373T, 2:374, 3:296 poultry farms 2:374 postharvest 2:374 definition 2:301 epidemiology 2:371 reservoirs 2:371 transmission to meat animals 2:371 hazard analysis and critical control point, Vienna sausage production 2:96, 2:96T human infection see Salmonellosis infection see Salmonellosis irradiation effects 2:143 isolation and identification 2:314, 2:368 conventional culture detection 2:368 detection of antibodies by enzyme immunoassay 2:369 enrichment procedure 2:313–314T, 2:314 plating procedures 2:313–314T pre-enrichment procedure 2:313–314T rapid detection methods 2:368 typing methods for epidemiology and outbreak investigation 2:368–369 multilocus sequence typing 2:369 multiple loci variable number of tandem repeats analysis 2:369, 2:369F phage typing 2:369, 2:369F pulsed-field gel electrophoresis 2:369, 2:369F mechanisms of pathogenicity 2:371 infection cycle 2:371 virulence mechanism 2:371 monitoring/incidence in meat animals 2:370T, 2:372 cattle 2:372 in cutting plants 2:372–373 pigs 2:370T, 2:372 poultry 2:370T, 2:372 at retail 2:373

at slaughter 2:372 cattle slaughterhouses 2:372 pig slaughterhouses 2:372 poultry slaughterhouses 2:372 surveillance systems, in pigs 2:221 taxonomy 2:367, 2:368T Salmonella bongori 2:367, 2:368T Salmonella enterica 2:367, 2:368T Salmonellosis 2:369–370 definition 2:367 in humans 2:18, 2:290, 2:368T, 2:370–371 incidence 2:18, 2:370T symptoms 2:18, 2:371 in meat animals 2:369–370 monitoring/incidence see under Salmonella transmission 2:371 in animal feed 2:371–372 see also Salmonella Salometer 1:445–446 definition 1:442 Salt 1:296, 3:79–80 bacterial growth retardation 1:296 canning heat treatment reduction 1:297 in chilling water 1:297 in cooking liquid 1:297 disadvantages of use 1:297 effect on water binding 1:268, 1:297 effect on water-holding capacity 1:278 emulsion formation 1:296–297 emulsion-type sausages 3:256 as flavor 1:297 in fresh meat packaging, patenting 3:47 as functional ingredient in meat products 1:7 functions 1:297 levels for bacterial inhibition 3:79T levels in food 1:297 meat/meat products 2:126, 2:126T lipid oxidation 1:411 meat tenderization 1:297 microbial growth, upper limits for 1:296T microorganisms, influence on 1:296 for preblending 1:296–297 protein extraction 1:296–297 reducing levels in processed foods 1:449T, 2:126 see also Salt reduction strategies use in curing 1:418, 1:436, 1:443 Wiltshire bacon curing 1:59, 1:59 Wiltshire bacon flavor 1:62 see also Brine; Curing; Salting Salt curing, hides 1:115, 1:119T Salt dew cells 3:51 Salted products cancer and 2:101 fish 3:342 Salting 2:446–447 definition 1:518 dry-cured ham production see under Dry-cured ham production historical perspectives 1:416, 1:436, 1:442 myofibrillar protein denaturation 2:446 optimization 2:446–447 see also Brine curing; Curing; Salt

Salt meter definition 1:416 see also Salometer Salt-pack curing, hides 1:115, 1:119T Saltpeter (potassium nitrate) 1:430 Wiltshire bacon curing 1:59 Salt reduction, low-salt meat batter 1:287 Salt reduction strategies brined products 1:423 comminuted meat products, strong emulsions with lower- or low-salt formulations 1:287–288 dry-cured products 1:429 Salt-soluble proteins definition 3:126, 3:256 see also Myofibrillar proteins Salt solution method, hygrometer calibration 3:52–53 Salt-tolerant microorganisms, Wiltshire bacon 1:61 Salty basic taste, meat 1:259 Samgyepsal gui (Korean dish) 1:546–547, 1:546F Samgyetang (Korean dish) 1:548, 1:548F Sample(s) handling, laboratory accreditation requirements 2:150 preparation, veterinary drug residue analysis see under Veterinary drug residue analysis pretreatment see under Chemical analysis methods size 1:191 test representative, for experiments 1:191 selection 1:190–191 size 1:191 Sampling 1:187–192 acceptance 1:192 determination of specifications 1:192 laboratory accreditation requirements 2:150 survey 1:191 representative test samples for experiments 1:191 sample size 1:191 Sanitary measures, definition 1:27 Sanitary status 2:219 definition 2:218 Sanitation plan, good manufacturing practice 2:94, 2:94F Sanitizer definition 1:508 see also Cleaning agents Saponification, cholesterol analysis in meats 1:215 Saponins, effect on methane production in ruminants 1:73 Sapovirus 2:391, 2:392F classification 2:391 genome organization 2:391 human infection 2:391 zoonotic transmission 2:391–392 Saran, packaging film chemistry 3:21

Index

Sarcocystis 3:35–38T intermediate hosts 3:35–38T equine species 3:40 ruminants 3:39 swine 3:40 Sarcolemma 1:154F, 1:156, 1:158F, 2:442 definition 1:148 Sarcomere definition 2:70, 3:431, 3:443 effects of mechanical tenderizing methods electrical stimulation 3:445–446 SmartStretchTM 3:446–447 tenderstretching 3:444, 3:445F ultrasonic waves 3:447–448 length see Sarcomere length shortening see Shortening structure 1:158F, 1:159, 1:163F, 1:358, 1:359F Sarcomere length definition 1:252, 3:452 effects of heating temperature 1:407, 1:408F measurement, tenderness measurement 3:453T, 3:458 meat toughness and 1:255F, 1:257 Sarcopenia, definition 2:118 Sarcoplasm 1:155, 2:442 contents 1:154F, 1:158F, 1:159, 1:162F, 2:442 Sarcoplasmic proteins 1:238, 1:238F, 1:267 effects of heating, chemical changes 1:404 functionality 1:267 emulsification 1:273 gelation 1:270 solubility 1:269 see also Muscle proteins, functionality see also Meat protein(s) Sarcoplasmic reticulum 1:157F, 1:358 definition 1:148, 1:358 muscle contraction role 1:156 see also Muscle contraction Sashimi, definition 3:336 Satellite cells 2:71F, 2:72 Saturated fatty acids 1:239–240, 1:240, 1:240T cardiovascular disease and 2:106 definition 1:130, 2:111 desaturation 2:115–116 kangaroo meat 3:352 meat composition modification 2:109 melting point characteristics 1:240T percent in meat 2:107 species differences in fatty acid composition 1:241 see also Fatty acid(s); Lipid(s) Saucisson, French 1:528, 1:551 Sausage(s) blood see Blood sausage Brazil and South America see under Brazil and South America Chinese 1:522, 1:522F, 1:523F, 1:524T coextrusion see Coextrusion cured, preparation 1:449–450

definition 1:518, 1:558, 3:241 dry/semidry see Dry/semidry sausages emulsified see Emulsified sausages fermented see Fermented sausages fresh see Fresh sausage German see German sausages liver see Liver sausage Mediterranean-type see Mediterraneantype sausages Middle Eastern 1:553 natural curing procedures 1:434 Northern-type see Northern-type sausages poisoning 2:330 see also Botulism Poland 1:558, 1:559, 1:559F see also Polish sausage (Polska Kielbasa) shelf-stable, hurdle technology use 2:346–347 smoked see Smoked sausage spice usage 1:306T summer 1:556 see also Comminuted meat products Sausage casings 3:81, 3:235–240 animal casings 3:235–237, 3:236F beef intestines 3:237, 3:237F hog intestines 3:235–236, 3:236F laminated 3:237 sheep intestines 3:235–236, 3:236F cellulose casings 3:238–239 definition 3:256 frankfurters 3:259 large-diameter (fibrous casings) 3:238–239 coextrusion 1:568, 3:239 dry/semidry sausages 3:249 fabric casings 3:239 fresh sausage 3:262 manufactured collagen casings 3:237–238 natural, definition 2:340 plastic casings 3:239 Sausage-cutting machine, patenting 3:48 Sausage meat 3:261 Sausage production chain-conveyor systems 3:132, 3:132F, 3:133F coextrusion systems 3:132, 3:133F patenting 3:47 see also specific types of sausage Sawing tools 1:458 Scalding 1:389–390 definition 1:142 pig carcasses 1:368–369, 1:389–390, 3:298–299 poultry/broiler carcasses 1:389–390, 3:305–306 definition 3:303 schedules 3:305, 3:305T Scallops 3:383–384, 3:385F common edible species 3:385T Schwartzwa¨lder Schinken (Black Forest ham) 1:531–532 definition 1:530 production process 1:531–532, 1:532F Schwartzwurst definition 1:530 see also Blood sausage

537

Scientists, meat research institutions 2:255–264 Sckinkenwurst 3:245 Scombroid poisoning 2:13, 3:342 definition 2:8 Scrapie 2:362, 2:364–365, 2:476 Scrapple 1:556, 3:246 Screening methods definition 1:217 veterinary drug residues 1:219, 1:219T Seafood freezing, effect on product quality 3:194 nutritional content 3:380 see also Finfish; Shellfish Sealing, multilayer packaging films 3:22–23 Sea salt definition 1:416 use in curing 1:443 Sea snails 3:385 Seasoned meats, traditional Chinese meat products 1:524T, 1:525 Seasonings 1:9, 1:420, 1:444 fresh sausage 3:262, 3:263T Sea transport, meat/meat products see Transport of meat/meat products Secondary antioxidants, warmed-over flavor prevention 1:414 Secondary myofibers see Muscle fibers (myofibers) Selective media 2:306, 2:308T, 2:312T Escherichia coli O157:H7 2:360 spoilage bacteria enumeration 2:308T Selective sweep, definition 3:357 Selenium 2:126 human diet 2:121 in meats 2:126 Self assessments, producers’ role in beef quality and safety 3:176 Self-drainage design, processing equipment 1:511, 1:512F Self-regulation 2:92–99 future prospects 2:98 systems 2:92–94 FMEA see Failure mode and effects analysis (FMEA) GMP see Good manufacturing practices (GMPs) HACCP see Hazard analysis and critical control point (HACCP) Semiboneless hams 1:447 Semidry sausages definition 3:248 see also Dry/semidry sausages Semitendinous muscle anatomy, sheep 1:154F distribution of myofiber types, sheep 1:161F see also Muscle Semivegetarians, meat hierarchy among 3:280, 3:280T Sensitivity, definition 1:187 Sensory aspects of meat quality 1:20, 1:20T evaluation 3:270 factors affecting/optimization of 3:267–271 cooking 3:270–271

538

Index

Sensory aspects of meat quality (continued) gender 3:268 genetics 3:268 guaranteed tenderness 3:271 preslaughter 3:268–269 processing 3:269 aging 3:270 cold shortening and/or toughening 3:269 electrical stimulation 3:269 hot and cold boning 3:269–270 packaging and storage 3:270 temperature and reduced aging 3:269 tenderstretch 3:269 production 3:268 species 3:268 visual impact at point of sale 3:268 meat texture and connective tissue role 1:323–324 muscle fiber type affecting 2:445–446 see also Meat quality Sensory assessment, fish freshness 2:9, 2:10T Sensory assessment, meat 3:272–279 beef 3:275–276 flavor 3:276–277 classical methods 3:272–273, 3:273F factors to be considered before performing sensory analysis 3:274–275 choosing cooking method 3:275 choosing core temperature 3:275 sample preparation and sensory setup 3:275, 3:275F lamb 3:275–276 flavor 3:276–277 meat products 3:277–278 color assessment 3:278, 3:278F performed by consumers 3:273–274, 3:274F performed by trained panel 3:272, 3:272F physical and chemical measurements of sensory-related properties 3:278 color measurements 3:278 see also Meat color, measurement odor measurements 3:278–279 physical texture analyses 3:278 pork 3:275–276 flavor 3:276, 3:276F examples of references used for training of panelists 3:277T rapid sensory methods 3:273 tenderness measurement 3:457–458, 3:457T Sensory characteristics dry-cured products see Dry-cured products role of fats 2:451 smoked meats see Smoked meats Sensory profiling test 3:272–273 Sensory quality, development, fermented sausages see under Fermented sausages Sensory science, definition 3:272 Sentience animals 3:108, 3:110 definition 3:108 Seollongtang (Korean dish) 1:548, 1:548F

Sepia 3:386 Septicemia Aeromonas 2:319, 2:320 definition 2:317 Sequelae, definition 2:367 Seroprevalence, definition 2:389 Serotyping, subspecies identification Listeria monocytogenes 2:349–350 thermotolerant Campylobacter 2:383 Serrano ham 1:448, 1:449T definition 2:87 presentation 2:88 salting 2:89 drying-maturation and cellar phase 2:90 resting period 2:90 washing 2:89 see also Dry-cured ham production Sewage sludge, management 2:158 Sewn casings, sausages 3:237 Sex (animals) connective tissue affected by 1:324 gender differences in growth patterns of body constituents 2:59–60 influence on sensory aspects of meat quality 3:268 Sex separate feeding, poultry 2:468 Shabu-shabu (Japanese dish) 1:545, 1:545F Shackling, pigs 3:297–298 Shank-off leg (American-style leg), lamb 1:463 Shear force 3:443 definition 1:329, 1:486, 3:267, 3:431, 3:443, 3:452 effects of mechanical tenderizing methods hydrodynamic treatment 3:448, 3:449F hydrostatic pressure 3:449, 3:450F tenderstretching 3:444, 3:444T time course changes during postmortem storage 1:363, 1:363F, 3:443, 3:444F ‘Shear force’ technique, meat quality determination 1:20 Shearing action, mechanical methods of tenderness measurement 3:455T, 3:456F Shearling leather 1:119 Shechita see Kosher slaughtering (shechita) Sheep 3:374–379 behavior during handling and transport see Animal behavior, during handling and transport biological types see Sheep breeds bovine spongiform encephalopathy and 2:364 callipyge see Callipyge sheep carcass chilling 1:146, 3:313 carcass composition 1:149F, 1:149T bone 1:164–165, 1:165T chemical profile of sheep meat 3:376 effects of breeds and genetics 3:376 effects of management 3:376 fat, distribution 1:164F muscle, anatomical features 1:151F see also Carcass composition carcass grading 3:312–313 carcass quality 3:376–377 effects of breeds and genetics 3:377

effects of management 3:377–378 effects of postslaughter management 3:378 factors affecting meat flavor 3:376–377 ovine somatotropin and 2:181–182 crossbreeding 1:20 domestication 3:359, 3:374 Eurasian wild sheep 3:359 feeding, general aspects 2:478–479 genetic improvement programs sire referencing scheme 1:24–25, 1:24F use of imaging techniques 1:23, 1:23F see also Genetic selection programs growth effects of breeds and genetics 3:375 effects of management 3:375–376 hide removal 1:113 intestines, as sausage casings 3:235–236, 3:236F listeriosis 2:351 meat see Sheep meat mitochondrial DNA 3:359 numbers/geographical distribution 2:212T, 2:213T, 2:214, 3:309 origins 3:359 production see Sheep production ruminal contents 2:471–472 scrapie 2:362, 2:364–365 slaughter see Sheep and goats, slaughterline operation Southern European breeds 3:359 world inventory 3:374–375 see also entries beginning lamb; Mutton; Ruminants Sheep and goats, slaughter-line operation 3:309–314 automation see Slaughter-line operation, automation electrical stimulation, chilling, and freezing 3:313, 3:313F, 3:314F evisceration see Evisceration exsanguination 3:310–311, 3:311F time to loss of brain function 1:562 future trends 3:313–314 head processing 3:311–312 mechanization 3:312 see also Slaughter-line operation, automation pelt removal 3:311, 3:312F processes 1:50T sheep and lamb carcass grading 3:312–313 stun box and restrainer design 3:90–91 stunning 3:310, 3:310F Sheep breeds 3:375 carcass composition and 1:19, 3:376 carcass quality and 3:377 growth and 3:375 hair breeds 3:375, 3:376, 3:377 Sheep meat chemical profile 3:376 taints, chemical analysis 2:495–496 see also Lamb (meat); Mutton Sheep pelts by-products 1:113T classification 1:112, 1:118T

Index

removal 3:311, 3:312F definition 3:309 Sheep production nutritional management 2:475–477 organic 2:201 systems 2:214–215, 2:214F, 2:215F extensive 2:214, 2:214F, 2:215F pastoralist 2:215 threats 2:215 Shelf life biltong 1:516 effect of smoking see under Smoking, traditional expected, canned meats 1:138–139 Shelf-stable, definition 1:555 Shellfish 3:380–387 crustaceans see Crustaceans definition 3:380 molluscs see Molluscs nutritional content 3:380 welfare issues 3:386 see also Fish Shellfish toxin, definition 2:8 Shewanella putrefaciens 3:391 enumeration media 2:308T, 2:309 Shiga toxin(s) (Stx) 2:358 hemolytic uremic syndrome complications 2:358 Shiga toxin 1 (Stx1) 2:358 Shiga toxin 2 (Stx2) 2:358 Shiga toxin-producing Escherichia coli (STEC) 2:19, 2:357T, 2:358 adherence factors 2:358 clinical significance 2:19, 2:358 definition 2:306 ecology 2:359 enrichment procedure 2:313–314T human infection 2:19 see also Hemolytic uremic syndrome (HUS) pathogenicity 2:358 plating procedures 2:313–314T pre-enrichment procedure 2:313–314T processed meat 2:359 refrigerated meat products 2:359 reservoirs 2:358 standard methods 2:311 transmission 2:358 Shingle-sliced bacon 1:57 Short-cut leg, lamb 1:463 Shortening 1:358, 1:359F cold see Cold shortening definition 1:329, 1:486, 3:267, 3:431, 3:443 heat 3:269 influence of temperature 1:358–359, 1:360F see also Cold shortening prevention, meat tenderness and 3:443 see also Tenderizing mechanisms, mechanical rigor see Rigor shortening see also Muscle contraction Short hairpin RNA (shRNA), definition 1:92 Shorthorn cattle 3:329 Shoulder, square-cut (lamb) 1:463

Shower system, liquid smoke 3:140, 3:141F Shrimp 3:380 common edible species 3:382T Shrink (retail losses) 3:16 definition 3:13, 3:16 Shrink packaging 3:31 definition 3:26 Shrink tunnel/bath 3:3–4 definition 3:2 Sichuan (Szechuan) cuisine 1:524 Sick animals, treatment in organic livestock production systems 2:199 Side pullers, cattle hide removal 3:286 Sievert (Sv), definition 2:140, 2:141 Significant figures 1:190 definition 1:187 Sika deer 2:194 Silastic implants, payout 2:63 Simmental cattle 3:329–330, 3:329F Singapore, wet markets future of 2:247 market forces 2:245 modern 2:246 Tekka Center 2:244F Singeing 1:390 pig carcasses 1:390, 3:299 Single-cell protein 1:299 Single chamber systems, vacuum packaging 3:30 Single-energy X-ray systems, meat composition measurement 2:485 Single-nucleotide polymorphisms (SNPs) 1:13 definition 1:97 in genomic selection 1:17, 1:17T genotyping of foodborne pathogens 2:299–300 Single-screw extruders 1:566–567, 1:566F Single-shell molluscs see Molluscs Singlet oxygen, definition 1:410 Sire reference schemes 1:24–25, 1:24F Skatole 3:276–277 as boar taint compound 1:98, 3:276–277, 3:277T control strategies development of genetic markers for low boar taint pigs 1:101–103, 1:102T effective dietary and management methods 1:100–101, 2:458 cutoff levels 1:98 factors affecting accumulation 1:98–99 sensitivity to 1:98 synthesis and metabolism 1:98, 1:99F Skeletal muscle beta-adrenergic agonist effects 2:67 growth physiology 2:77–78 somatotropin effects 2:77T steroid hormone effects 2:65, 2:65F see also Muscle Skin(s) 1:112 by-products 1:113T chemical composition 1:112–113, 1:118T contamination with 2:22, 2:22T layers 1:112, 1:118T see also Hide(s)

539

Skin color, poultry carcass, nutrition and 2:469 Skinners, pork 1:35–36, 1:36F Skin packaging definition 3:2 vacuum skin packaging machinery 3:5, 3:5F Skintight packaging 3:31 advantages/disadvantages 3:31 definition 3:26 frozen meats 3:29–30 Slaughter definition 1:561, 3:280, 3:309, 3:407, 3:422 ethics and law 3:280–283 applied ethics and decision-making 3:280–281 ethics of stunning 3:281–283 electrical stunning 3:409 religious ethics 3:282 stereotypes in ethical discussions on animal welfare and slaughter 3:281, 3:281T market specifications 2:233 religious see Religious slaughter stress during 3:85 see also Preslaughter stress see also Abattoirs; Immobilization; specific animal species; Stunning Slaughter-line operation buffalo 3:291 camel 3:291 cattle see Cattle slaughter process crocodile 3:293 deer 3:290–291 geese and ducks 3:293 horse 3:291–292 kangaroo 3:293 ostrich, emu, and rhea 3:292–293 patented processes 3:44 pigs see Pig slaughter/slaughter-line operation poultry see Poultry, slaughter-line operation quail 3:293–294 rabbits see Rabbits reindeer and moose 3:292 sheep and goats see Sheep and goats, slaughter-line operation slaughtering as source of microbial contaminants in fresh meat 2:285–286 steps 3:422 Slaughter-line operation, automation 1:43–52 cattle slaughter 1:46–47 bunging and sealing 1:47, 1:48F carcass cleaning 1:48 carcass opening 1:47–48 carcass splitting 1:48 classification and grading 1:48 dehiding 1:47 evisceration 1:48 hock cutting 1:47 lairage and stunning 1:47 see also Cattle slaughter process

540

Index

Slaughter-line operation, automation (continued) opportunities and challenges 1:43 ovine slaughter 1:48–49, 1:50T, 3:312 carcass classification and grading 1:52 inverted dressing 1:48–49 mechanization for task replacement 1:39–40, 1:49 robotic automation 1:49–52, 1:50F, 1:51F see also Sheep and goats, slaughter-line operation pig slaughter 1:43–44, 1:44T clean part of slaughter line 1:44–46, 1:44T, 1:45F, 1:46F, 1:47F unclean part of slaughter line 1:44, 1:44T, 1:45F see also Pig slaughter/slaughter-line operation see also Cutting and boning, automation Slicers 3:130 Slow-fermented sausages 3:249 see also Dry/semidry sausages Slow-twitch fibers aerobic metabolism 1:155–156 contracture 1:362–363 distribution in muscles 1:161F functions 1:155 innervation 1:155, 1:160F myosin ATPase activity 1:155, 1:160F see also Muscle fibers (myofibers) Small ruminants 3:374 definition 3:374 factors affecting growth, carcass composition, and carcass quality 3:375 carcass composition 3:376 chemical profiles of sheep and goat meat 3:376 effects of breeds and genetics 3:376 effects of management 3:376 carcass quality 3:376–377 effects of breed and genetics 3:377 effects of management 3:377–378 effects of postslaughter management 3:378 factors affecting meat flavor 3:376–377 growth effects of breed and genetics 3:375 effects of management 3:375–376 immobilization, emerging economies 3:419 numbers/geographical distribution 2:212T, 2:213T, 2:214 see also Goat(s); Ruminants; Sheep SmartStretchTM 3:446–447, 3:447F Smells effect on animal behavior 3:86 see also Odor(s) Smoke as flavor 1:300 liquid see Liquid smoke (smoke condensate)

natural, warmed-over flavor prevention 1:414 traditional production 3:140, 3:140F see also Smoking, traditional wood see Wood smoke see also Smoking Smoke chambers, liquid smoke application 3:317, 3:317F Smoke composition, wood smoke 3:322, 3:322T definition 3:321 Smoked fish 3:342 Smoked ham, Polish 1:558 Smoked meats bacon 1:446 cooking 3:134, 3:134–135, 3:136 see also Cooking processes diffusion and interactions in 3:322–323 pigments 1:250 Polish 1:558 sensory properties definition 3:321 development, role of smoke 3:323–324 traditional Chinese meat products 1:524T see also specific products Smoked sausage 3:245 uncooked 3:261 Smoke generators, traditional smoking 3:140, 3:140F, 3:321, 3:321F, 3:325 Smokehouses 1:387, 3:131, 3:321, 3:321F, 3:325, 3:326F see also Batch ovens Smoke phenols 3:322, 3:322T definition 3:321 Smoke regeneration, liquid smoke application method 3:317, 3:318F, 3:318T Smokie links 3:245 Smoking 3:80 brine-cured meats 1:422–423 color development, mechanical conditioning and 3:145 definition 1:558, 3:64, 3:78 dry-cured ham production 2:89–90 fermented sausages 2:3, 3:325 preservative action 3:321, 3:323 definition 3:321 see also Liquid smoke (smoke condensate) application; Smoking, traditional Smoking, traditional 3:321–327 deposition on smoked goods 3:322 diffusion and interactions in smoked meats 3:322–323 effect on shelf-life of meat products 3:323 antimicrobial activity 3:323 antioxidant activity 3:323, 3:324F definition 3:321 equipment 3:325 smoke generators 3:140, 3:140F, 3:321, 3:321F, 3:325 smokehouses 3:321, 3:321F, 3:325, 3:326F health hazards associated with 3:324–325 definition 3:321

liquid smoke (smoke condensate) application vs. 3:315, 3:316, 3:318 role of smoke in developing characteristic sensory properties of smoked goods 3:323–324 smoking procedures 3:325–326 see also Wood smoke Smoking equipment 3:140–141, 3:140F, 3:141F traditional smoking see under Smoking, traditional Snails, consumption 2:197 Snakes 2:196 Snorkel machines 3:4–5, 3:4F, 3:30 CAPTECH chamber 3:6–7, 3:7F, 3:18 mother bag 3:7 SNP BeadChips 1:17, 1:17T Soap animal by-product use 1:129 tallow use 1:130 Socioeconomic status, definition 2:135 Soclap (Society, Oneself, Customer/client, Legal, Animal, and Profession) 3:281 definition 3:280 Sodium in meat/meat products 2:126, 2:126T reduction brined products 1:423 see also Salt reduction strategies requirements, poultry 2:464T, 2:465–466 Sodium chloride as curing ingredient 1:418 see also Salt Sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE), meat species determination 2:266 Sodium hexametaphosphate, as secondary antioxidant 1:414 Sodium ions, meat tenderization 3:432, 3:432–433, 3:433–436, 3:436F Sodium lactate 1:298–299 Sodium nitrate see Nitrate Sodium nitrite 1:298 bacon curing solutions 1:56 emulsification processes 3:257–258 final temperatures 3:257–258, 3:258T legal requirements 1:201T, 1:418, 1:443 in vacuum packaging films 3:32 Wiltshire bacon curing 1:59–60 see also Nitrite Sodium phosphates 1:299 Sodium tripolyphosphate, as secondary antioxidant 1:414 Soft-tissue infections, Aeromonas 2:320 Soil, Clostridium perfringens 2:337 Soil bacteria, antimicrobial resistance 2:417 Soil contamination, meat 2:23, 2:23T Soils (in meat production environment) 1:508–509 classification 1:509 composition 1:510–511 definition 1:508, 1:509 removal from equipment see Equipment cleaning solubility characteristics, cleaning agents and 1:510–511, 1:511T

Index

surface interactions 1:509 see also Surface energy ‘Soldering iron test,’ boar taint 1:100 Solid foods, drying see Drying Solid-phase extraction (SPE) 1:174 veterinary drug residues 1:218 Solid-phase microextraction 1:174 Solubility, protein see Protein solubility Solutions, drying see Drying Somatic cell nuclear transfer (SCNT) 1:92–93 Somatic cells cloning 1:84 efficiency 1:87 cryopreservation, rare livestock breeds 1:90–91 gene targeting 1:91 Somatogenic, definition 2:49 Somatomedin hypothesis 2:52 Somatostatin (SS) see Somatotropin releaseinhibiting factor (SRIF) Somatotroph, definition 2:49 Somatotrophic, definition 2:49 Somatotrophic axis, postnatal growth 2:52 Somatotropin (ST) 2:181 adipocyte lipid accumulation 2:80 adipose tissue metabolism 2:183 bone deposition increases 2:182 carcass lean-to-fat ratio 2:182 carcass quality 2:181–182 daily administration 2:78 definition 2:181 fetal lipogenesis 2:51 functions 2:181 growth 2:76–77 growth promoters, additive effects 2:182 health aspects 2:183–184 historical aspects 2:181 insulin resistance 2:183 lean growth stimulation 2:52 lipogenesis 2:80 meat collagen content 2:184 meat quality 2:184 physicochemical characteristics 2:184 meat sensory aspects 2:184–185 metabolic potentials 2:184 muscle characteristics 2:184 muscle development role 2:74 muscle fiber-type properties 2:184 muscle growth 2:65, 2:78 estradiol and 2:65 during gestation 2:50 nutrient partitioning 2:181 performance effects 2:181–182 physiological effects 2:76–77, 2:77T postnatal growth 2:52 protein deposition increases 2:182 pubertal growth females 2:53 males 2:53 regulators 2:181 routes of administration 2:181 see also Growth hormone-releasing hormone (GHRH) Somatotropin release-inhibiting factor (SRIF)

definition 2:181 maternal immunization against 2:52 placental, fetal growth 2:51 postnatal growth 2:52, 2:52 somatotropin regulation 2:181 Somites 2:71 definition 2:70 Sonic Hedgehog, embryonic growth 2:50 Sorbitol 1:297 Sorbitol MacConkey Agar, Escherichia coli O157:H7 detection 2:360 Soup-type Korean meat-based dishes see under Korea Sour basic taste, meat 1:259 Sous vide method 1:373–374 South Africa game meat industry 3:346, 3:349 provincial meat research institution 2:257–261T see also Africa South African ethnic meat products see Biltong South America see Brazil and South America Southeast Asia meat products and cuisine 1:522–526 see also specific countries South Korea antibiotic growth promotant policy 2:175T provincial meat research institutions 2:257–261T see also Korea Soya 1:299 Soyabean protein, feeding to beef cattle 2:478 Soy flour 1:3, 1:293 definition 1:1 Soy ingredients, as meat extenders 1:3 Soy protein(s) cooked sausages 3:242 use in comminuted meat products 1:293 Soy protein concentrate (SPC) 1:3, 1:293 Soy sauce 1:523, 1:524T, 1:525 definition 1:522 Spain, meat research institutions private industrial 2:262–263T provincial 2:257–261T Span error, thermometer calibration 3:61, 3:61F Spanish chorizo 1:551, 1:551F Spanish country-cured hams, fungal profiles 2:399 Species determination (meat species) 2:265–269 deoxyribonucleic acid-based methods 2:265, 2:266–267, 2:268T polymerase chain reaction-based methods see Polymerase chain reaction-based methods, meat species determination protein-based methods 2:265, 2:265–266, 2:268T chromatographic techniques 2:266, 2:268T electrophoretic techniques 2:266, 2:268T

541

enzyme-linked immunosorbent assays 2:265–266, 2:268T Species effects heat-induced meat flavor 1:380 sensory aspects of meat quality 3:268 Species identification, thermotolerant Campylobacter 2:383, 2:383T Specific heat capacity 3:462–463 at constant pressure 3:462 at constant volume 3:462 in volumetric terms 3:463 Specificity, definition 1:217 Specific pathogen free (SPF) definition 2:187 perfect disease 2:188 Specific pathogen free (SPF) pig production 2:187–188 advantages 2:188 biosecurity 2:188–189, 2:188T commercial farms 2:187–188 diseases controlled 2:188, 2:188T infection introduction 2:188–189, 2:189F principles 2:188 Spectrometry, guided microwave see Guided microwave spectrometry Spectrophotometry 1:175 atomic absorption see Atomic absorption spectrometry (AAS) atomic emission spectrometry 1:176 definition 1:175 luminescence spectrometry 1:175 near infrared spectrometry see Near infrared spectroscopy nuclear magnetic resonance spectrometry see Nuclear magnetic resonance (NMR) spectrometry UV–Vis spectrometry 1:175 Specular reflection definition 2:164 theory of meat color measurement 2:168 Spermidine 3:221 toxicological effects 3:222T Spermine 3:221 toxicological effects 3:222T Spices 1:9, 1:300, 1:302–306, 1:444, 3:81 applications/uses 1:302T, 1:305 characterization purposes 1:305 aroma detection 1:302–304 Bacillus cereus contamination 2:328 characteristics 1:302–305 commonly used 1:303–304T components 1:302–305 decontamination methods 1:304–305 definition 1:304 economics 1:302 flavor detection 1:302 historical aspects 1:302 leading producers 1:302T limits for meats 1:300, 1:305T as microorganism source 1:304–305 problems with 1:300 production 1:304–305 in sausages 1:306T usage 1:305–306 warmed-over flavor prevention 1:413, 1:415 see also individual spices

542

Index

Spinal cord removal cattle 3:288 pigs 3:301 Spiny lobster 3:380, 3:381F, 3:382T Spiral computed tomography definition 2:480 meat composition measurement 2:487 Spiral ovens 3:133, 3:133F, 3:135 see also Cooking processes Spiral plating, spoilage bacteria 2:307 Spiramycin, small intestine microbial activity changes 2:173 Spirometra 3:35–38T Spleen, as edible by-product 1:111 Splotch (PAX3), myogenic differentiation 2:50 Spoilage 3:394 bacterial, preserved meats 3:392, 3:392T biltong 1:516 minced meats see Minced meats by molds see under Mold(s) overwrapped packages 3:16 by yeasts 2:402, 3:392–393, 3:392T Spoilage, factors affecting 3:388–393 aerobic spoilage fat and organ tissues and minced meats 3:390 raw muscle tissue 3:388–390, 3:389T anaerobic spoilage 3:390–391, 3:391T bacterial spoilage of preserved meats 3:392, 3:392T in modified and controlled-atmosphere packagings 3:391–392 oxidative and enzymatic 3:394–400 enzymatic factors 3:394, 3:399 oxidation of pigments 3:394, 3:397–398 oxidation of proteins 3:394, 3:398–399 peroxidation of lipids 3:394, 3:394–395 see also Warmed-over flavor (WOF) spoilage by yeasts and molds 3:392–393, 3:392T Spoilage bacteria 2:306–307 aerobic plate count 2:307–308 characteristics 2:306–307, 2:307T definition 2:306 enumeration media 2:307–308, 2:308T aerobic plate count 2:307–308 indicator bacteria 2:308, 2:308T psychrotrophic plate count 2:307–308 irradiation effects 2:143 plating methods 2:307 sample preparation 2:307 standard methods 2:306–307 see also individual species Spoilage flora definition 3:388 see also Spoilage; Spoilage bacteria Sponging compounds, fatliquoring 1:122 Spontaneous blinking, definition 3:413 Spore(s) Bacillus cereus 2:324, 2:324–325, 2:325, 2:326, 2:326T Clostridium perfringens 2:335 definition 2:335

Spore-forming bacteria definition 1:64 prevention of sporulation 1:69 Sporotrichum, meat spoilage 2:401 Sporulation, Clostridium perfringens 2:335–336, 2:337 Spray chilling 2:226, 3:180 beef carcasses 1:146, 3:289 pork carcasses 1:147 primary chilling, poultry carcasses 3:185 product surface appearances 3:180 secondary chilling 3:187 Spray dryer 1:478, 1:478F Spray pumping, brine 1:422 Spray thawing 3:206, 3:206F Spread plate technique, spoilage bacteria 2:307 Springbok (Antidorcas marsupialis) meat 3:349, 3:351T SPS Agreement 1995 2:231 definition 2:231 Squamous cells, definition 2:471 Squid 3:386, 3:386F Stability assessment, meat emulsions/batters 1:287 Stabilization mechanisms, meat emulsions/ batters 1:286–287 Stag, definition 2:190 Staging alley, definition 3:84 Stainless steel, as surface in food production environments/equipment 1:509T Stamping out, infectious disease eradication 2:187 Standard curves 1:188–190, 1:189F definition 1:187 Standard developing organizations (SDOs) 1:193–194 definition 1:193 Standard deviation, definition 1:187 Standard methods 2:306–316 chemical analysis see Chemical analysis, standard methods definition 2:306, 2:306 international agencies developing/ assessing 2:306 meatborne pathogens see Meatborne pathogens Standard Operation Procedures (SOPs), definition 3:64 Standard Sanitation Operation Procedures (SSOPs), definition 3:64 Staphylococcal enterotoxins 2:377–378 Staphylococci, coagulase-negative, use in meat fermentation 2:1, 2:3 Staphylococcus aureus 2:290, 2:376–381 characteristics 2:376–377 organism 2:376–377 staphylococcal enterotoxins 2:377–378 foodborne illness 2:290 characteristics 2:379–380 control and preventive measures 2:380 epidemiology 2:380 as indicator organism 2:304 isolation and identification 2:378–379 direct plating 2:314–315, 2:315T

enumeration and detection 2:314–315, 2:378–379, 2:378F identification 2:379, 2:379T typing 2:379 methicillin-resistant see Methicillinresistant Staphylococcus aureus (MRSA) prevalence in meat products 2:376, 2:377T protection against infections in dairy cattle, genetic engineering 1:94–95 Starch(es) 1:3 definition 1:1 as meat extenders 1:4 retrogradation 1:4 definition 1:1 thermoplastic 1:568 Starter cultures 1:300 definition 1:76 fermented sausage production 2:1, 2:3, 3:248, 3:248–249 nitrate-reducing, in natural curing 1:433 Statistical analysis 1:187 collaboratively validated methods 1:195 Statistical model definition 2:425 meat quality 2:428–429 Statistical requirements, analysis techniques 1:187–188 confidence intervals 1:188, 1:188T determining unknowns 1:190 measurement of central tendency 1:187–188 selecting test samples 1:190–191 significant figures 1:190 standard curves 1:188–190, 1:189F Steam decontamination of fresh meat 2:276–277 surface decontamination 1:389 Steam cookers 3:134 Steam cooking 1:387 Steamed meat-based dishes Japanese 1:544–545, 1:545F Korean see under Korea Steam pasteurization 2:277 definition 2:276 pig carcass treatment 3:301–302 Steam tables, warmed-over flavor 1:413 Steam vacuum 2:277 definition 2:276 Stearic acid 1:224, 1:226–227, 2:107 definition 2:111 lipid melting points and 1:233, 1:233F palmitoleic acid vs., subcutaneous adipose tissue lipids 1:232, 1:232F positional distribution 2:114 see also Fatty acid(s) Stearoyl-coenzyme A desaturase (SCD) 1:224–225, 1:228–229, 2:115–116 activity 1:230, 1:230F adipose tissue 1:230, 1:230F Japanese Black cattle 1:232 effects of conjugated linoleic acid 1:229–230 gene expression 1:224, 1:226F Stem cells, embryonic see Embryonic stem cells

Index

Stem errors definition 3:57 temperature measurements 3:62, 3:62F Stemphylium 2:395, 2:400F Stereotypic behavior animal welfare 3:105 definition 3:102 see also Animal behavior Sterilization 1:385, 1:385–386 canned meat products 1:385 see also Canning operations flame 1:386 food irradiation 2:142 meat products in glass containers/flexible pouches 1:386 see also individual methods Steroid hormones in animal production 2:62–63 adipose tissue 2:65–66 bans on use 2:62 bone growth 2:66 compound classifications 2:62–63 effects 2:64–65 excretion 2:64 feed consumption stimulation 2:64 genomic steroid actions 2:64 muscle growth effects 2:65, 2:65F nongenomic steroid actions 2:64 plasma concentrations 2:63, 2:63F practical considerations 2:66 reimplant programs 2:63F, 2:66 target cell types, delivery to 2:63–64 beta-adrenergic agonists and, comparative efficacy 2:68 bovine somatotropin and 2:68 half-lives 2:64 meat tenderness and 2:68 somatotropin and, additive effects 2:182 see also individual hormones Steroid implants 2:62 dissolution 2:63 dosages 2:63 efficacy 2:62, 2:63F implant site abscessation 2:66 payout 2:63 plasma concentrations 2:63, 2:63F tylosin tartrate pellets 2:66 Steroid receptors, up/downregulation 2:65 Sterols 1:241 see also Cholesterol Stewing, meat 1:373 Stick/sticking definition 1:561, 3:209 halal slaughter 3:211 kosher slaughter 3:210 pigs 3:298 see also Exsanguination Stimulation, electrical see Electrical stimulation (ES) Stitch pumping bacon curing 1:55–56 brine 1:422 Stochastic model, definition 2:430 Stock, edible by-products and 1:109 Stockmanship, animal welfare 3:103, 3:104T

Stockyards design 3:92–93, 3:92F drains and washdown 3:93 flooring surface 3:92–93 layout 3:93 use of powered gates 3:93 see also Lairage/lairaging Stomach, ruminant, chambers 2:471–472, 2:471F, 2:472F Stomach cancer 2:102 Stomach ulcers, somatotropin-treated pigs 2:184 Storage, frozen see Frozen storage Storage life definition 3:191 frozen meat 2:228 Storage temperature effect on spoilage aerobic spoilage 3:388–389, 3:389, 3:390 anaerobic spoilage 3:391, 3:391T spoilage by yeast and molds 3:392–393, 3:392T frozen meats 2:228 sensory aspects of meat quality and 3:270 Strain theory, meat tenderness 1:253 Stray voltage, definition 3:57 Streaky bacon see Belly bacon Strecker aldehyde 1:394, 1:395F Strecker degradation/reaction 1:394, 1:395F cooked meat flavor 1:258–259 definition 2:1 fermented sausage flavor development and 1:381 Streptococci, fecal, as indicator organisms 2:303 contaminated raw materials 2:303 inadequate pathogen destruction processes 2:304 Streptococcus suis 2:342–343 Streptomycin-thallous acetate actidione agar (STAA), Brochothrix thermosphacta enumeration 2:308T, 2:309 Stress behavioral indicators 3:84–85 eye white response 3:85 vocalizations 3:84–85, 3:100 definition 3:95 effects, in fish 3:343 preslaughter see Preslaughter stress during slaughter 3:85 Stress-induced immunosuppression, definition 3:102 Stress reaction proteins, hurdle technology, effects on 2:345 Stress response 3:95 Stromal proteins see Connective tissue proteins Strombidae (conches) 3:385 Strong alkaline cleaners 1:513 Stuff, definition 3:241, 3:256 Stuffing cooked ham production 2:84–85 fermented sausages 2:2 mechanically conditioned meats 3:145

543

Stun box animal behavior and 3:85, 3:86 cattle stunning 3:284–285 definition 3:84 design 3:90–91, 3:90F movement to (from lairage) 3:100 Stunners definition 3:84 pneumatic 3:415, 3:415F Stunning carcass quality and 1:563 cattle 3:284–285 automated 1:47 bulls, considerations 3:415, 3:415F electrical stunning 3:410–411 New Zealand 1:488 see also Mechanical stunning conscious slaughter vs., religious slaughter 3:212–213 definition 1:366, 1:561, 3:309, 3:421, 3:422 electrical see Electrical stunning ethics 3:281–283 exsanguination blood loss 1:562 farmed fish see Farmed fish, stunning and killing gas see Gas stunning goats 3:310, 3:310F meat quality and 1:563 pigs 1:368, 1:368T mechanical see Mechanical stunning pigs see Pig slaughter/slaughter-line operation poultry 3:303–305 electrical stunning 3:303–304, 3:411 welfare aspects 3:304, 3:305F gas stunning 3:304, 3:401–402, 3:419 restraints 3:284–285 sheep 3:310, 3:310F see also Immobilization; Slaughter Stun quality, assessment 3:414–415 Stuttgarter Schinkenwurst, definition 1:530 Subclinical infection, definition 2:367 Subcutaneous fat 1:20, 1:223, 1:223F definition 1:19 deposition patterns 2:59 gender differences 2:60 distribution 1:159–160 cattle 1:165F sheep 1:164F fatty acid composition 1:224–226, 1:226F, 1:227F relative development in lean, average, and fat animals 1:160, 1:165T see also Adipose tissue; Fat; Lipid(s) Subjective assessments, pig carcass classification 1:316 Subjective experience of animals, animal welfare and 3:110 Subprimal, definition 1:458, 1:458–459 Subprimal cuts, definition 3:13 Subspecies identification, thermotolerant Campylobacter by pulsed-field gel electrophoresis 2:383 by serotyping 2:383 Sub-therapeutic, definition 2:172

544

Index

Subtyping definition 2:297 DNA, foodborne pathogens see Foodborne pathogens, DNA subtyping Suckler beef extensive production 2:201 see also Beef cattle Sucrose, as sweetener in meat products 1:9 Suffering 3:102, 3:110 avoidable, definition 3:418 capability to experience finfish 3:342–343 shellfish 3:386 Suffolk sheep, scrapie susceptibility 2:364–365 Sugar(s) bacterial growth retardation 1:297 color enhancement 1:297 in cured meats 1:297 levels 1:298 flavor enhancement 1:297 meat peelability and 1:297 Sukiyaki (Japanese dish) 1:545 Sulfmyoglobin 1:247T, 1:248 Sulfur-containing compounds, generated via Maillard reaction see under Maillard reaction Sulfurospirillum 2:340 Sulfurous-containing volatiles, flavor aromatics 1:258 Summer sausage 1:556, 2:2–3, 2:2 Sundae (Korean-style blood sausage) 1:547F, 1:548 Supercooling (undercooling) 3:181, 3:461 Supercritical fluid extraction (SFE) 1:182, 1:207 Superior spinous process, definition 1:458 Superoxide dismutase 3:399 definition 3:394 Supply definition 2:248 pricing see Meat pricing systems vertically integrated systems 2:251–252, 2:252 Supply chain, retail 2:248 Surface coloring agents 1:300 Surface conditioning, biofilm formation 1:64, 1:65T, 1:66F Surface energy definition 1:508 soil removal and 1:509–510, 1:510F Surface heat decontamination processes see Thermal surface decontamination processes Surface heat transfer coefficient 3:180, 3:197 Surface meat color measurement 2:491–492 pork 3:365–366, 3:366F Surfaces (food production environments/ equipment) characteristics 1:508–509, 1:509T cleaning see Equipment cleaning Surface temperature measurements, error sources 3:62–63, 3:62F Surgical procedures, animal welfare 3:103

Surimi 1:292, 2:272 composition 2:272 definition 1:267, 3:336 gel weakening phenomenon 1:271 Surveillance hazard mitigation and 2:219 see also Meatborne hazards, mitigation laboratory accreditation procedure 2:148 Survey sampling see Sampling, survey Sushi 1:543, 1:543F Suspensions, drying see Drying Sustainability assessment see Life cycle analysis (LCA) definition 3:427, 3:427 optimization see Meat production, optimization of efficiency and sustainability Suzhou-style flavor, traditional Chinese meat products 1:524 Swamp buffalo 2:192 Swann Committee, UK 2:173 Sweden, meat research institutions private industrial 2:262–263T provincial 2:257–261T Sweet basic tastes, meat 1:259 Sweetbreads 1:108 Sweeteners 1:297–298 meat products as curing ingredient 1:420, 1:444 as functional ingredient 1:9 preservative action 1:420, 3:80 Swine husbandry, pork quality and 3:169 as intermediate hosts for parasites 3:39–40 see also Pig(s); Wild boar Swiss Animal Welfare Act 3:111 Switzerland, national meat research institution 2:255–256T Sympathetic nervous system (SNS), stress assessment 3:106 Synbiotics, in meat products 2:35 Synovex, muscle growth 2:78 Syntans, retanning 1:121 Synthetic androgens, growth stimulation 2:53 Synthetic antioxidants, warmed-over flavor prevention 1:413 System control definition 3:159 quality assurance strategy in meat production chain 3:160–163, 3:162F Szechuan cuisine 1:524

T Tabak manss 1:539 Taco fillings 3:246 Taenia 3:35–38T intermediate hosts 3:35–38T lagomorphs 3:40 ruminants 3:39 swine 3:39, 3:39–40 Taenia asiatica 3:35–38T, 3:40 Taenia hydatigena 3:35–38T, 3:39 Taenia ovis 3:35–38T, 3:39

Taenia saginata 3:35–38T, 3:39 Taenia solium 3:35–38T, 3:39–40, 3:39 Taiwan, provincial meat research institution 2:257–261T Tallow 1:130 commodity trading standards 1:130T fatty acid profile 1:130, 1:131T, 1:132T as feed ingredient 1:130 specifications 1:130 Tambada rassa 1:540 Tandoori 1:538–539 definition 1:538 Tannin, retanning 1:121 Tanning 1:117, 1:120–121 deliming 1:119 hide wringing/setting 1:121 retanning 1:121 soaking 1:117 stages 1:123T types 1:120 Tapered myofibers 2:73 Tar fraction definition 3:315 smoke condensates 3:316 Target pathogen definition 2:412 zoonotic pathogens vs. 2:413 Taste 1:377–378, 3:276 basic, meat 1:259 dry-cured products 1:428, 1:428T see also Flavor Taste buds, flavors sensed 1:302 Tawing process 1:121 Taxonomy Listeria monocytogenes 2:348 Salmonella 2:367, 2:368T Taylorism 3:160 definition 3:159 Technical barriers to trade (TBT) agreements 2:146–147 Teeth, contamination with 2:22, 2:22T Teewurst definition 1:530 production process 1:534, 1:534F Ru¨genwalder see Ru¨genwalder Teewurst Tegu lizards 2:196 Temperate aromatics see Herbs Temperature air see Air temperature control, for sea transport of meat 2:237 cooking see Cooking core see Core temperature determining moisture content from 3:54 effects, muscle/meat aging/tenderness 1:331–332, 1:332F, 1:334, 1:334F reduced aging 3:269 pH measurements 1:265, 1:265F postmortem muscle 1:360F, 1:361T, 1:362–363, 1:362F time of onset of rigor mortis 1:360, 1:361T water-holding capacity 1:278 freezing see Freezing temperature muscle fiber type affected by 2:445 product, brine injection and 3:125

Index

SI units 3:460 storage see Storage temperature Temperature-based treatments, decontamination of fresh meat 2:276–277 Temperature logging 3:61 Temperature measurements 3:57–63 cooking processes 3:136 data logging 3:61 error sources 3:61–63 air temperature measurement 3:62–63 locating thermal centre see Thermal center stem errors 3:62, 3:62F surface temperature measurement 3:62–63, 3:62F instruments see Thermometers Temperature variation, ovens see under Cooking processes Tempering 3:202 definition 3:202 physical aspects 3:202–203 quality aspects 3:203 see also Thawing Template definition 2:294 see also Polymerase chain reaction (PCR) Tempura (Japanese dish) 1:544 Tendercut 3:269, 3:444–445, 3:445F Tenderization 1:329–330, 3:81, 3:438 blade 3:447, 3:448F cooked ham manufacture see Cooked ham production definition 1:329, 3:267, 3:431, 3:432 proteomic investigations 3:156–157 see also Aging, meat; Electrical stimulation (ES); Muscle; Tenderness Tenderizers 1:10 Tenderizing mechanisms, chemical 1:336, 3:431–437 injection of acids/other compounds 3:433, 3:436T injection of metal ions and ionic strength 3:432–433, 3:432F, 3:434–435T see also Calcium-activated tenderization nonenzymatic tenderization mediated by calcium ions 3:436–437 rigor bonding 3:432 vascular infusion 3:433–436, 3:436F see also Aging, meat; Muscle Tenderizing mechanisms, enzymatic 3:438–442 exogenous enzymes 3:441 definition 3:438 endogenous enzymes vs. 3:438 role of endogenous proteases 3:438 calpain system see Calpain(s) caspases 3:441 cathepsins see Cathepsins exogenous enzymes vs. 3:438 Tenderizing mechanisms, mechanical 3:443–451 carcass methods 3:443, 3:443–444 electrical stimulation see Electrical stimulation

tendercut 3:269, 3:444–445, 3:445F tenderstretching see Tenderstretch cut methods 3:443, 3:446 blade tenderization 3:447, 3:448F freeze–thaw 3:450 hydrodynamic pressure 3:448–449, 3:449F hydrostatic pressure 3:449–450, 3:450F Pi-Vac Elasto-Pack Systems 1:454, 3:5, 3:5F, 3:31, 3:446, 3:446F SmartStretchTM 3:446–447, 3:447F ultrasonic waves 3:447–448 see also Aging, meat; Muscle Tenderness 3:156, 3:267–268, 3:452 aging effects 1:257 application of genomic technologies 2:37 collagen content and 1:257–258, 1:258T collagen role 1:323 complexity, tenderness measurement and 3:457, 3:458T connective tissue properties of meat 1:323, 1:324 cooked vs. uncooked meat 3:454–456 definition 1:252, 2:489 descriptive terms 3:452–454 double muscled animals 1:344 effect of cooking temperatures 1:330, 1:330F, 3:454F, 3:456 guaranteed 3:271 heated meat 1:407–408 see also Meat protein(s), effects of heating influence of rigor mortis 1:363, 1:363F intrinsic determinants 3:453T, 3:454 marbling 1:253 as indirect measure 1:256–257 meat from double-muscled animals 1:467T, 1:469 muscle fiber type affecting 2:445–446 muscle myofibrillar proteins 1:257 muscle structural components 1:257 pork see under Pork proteomic investigations 3:156 scales 3:452–454, 3:452F sensory evaluation 3:443 variability, aging and 1:332–333 see also Electrical stimulation (ES); individual meats; Sensory aspects of meat quality; Tenderization Tenderness measurement 3:452–459 collagen content 3:453T, 3:458 collagen solubility 3:453T, 3:458 complexity of tenderness and 3:457, 3:458T cooked vs. uncooked meat 3:454–456, 3:454F intramuscular fat content 3:453T, 3:458 meat color 3:458 mechanical methods 3:455T, 3:456–457, 3:456F stages 3:455F myofibrillar fragmentation index 3:458–459 near infrared spectroscopy 2:491, 3:458 sarcomere length 3:453T, 3:458 scales 3:452–454, 3:452F

545

SDS-PAGE and Western blotting 3:458 sensory methods 3:457–458, 3:457T ultimate muscle pH 3:453T, 3:458 video image analysis 3:458 see also Sensory assessment, meat Tenderometers 1:337 definition 3:452 Tenderstretch 3:269, 3:443–444, 3:444F, 3:444T, 3:445F Tendons, collagenous 1:149–150, 1:153F Terefah, definition 3:209 Teriyaki (Japanese dish) 1:544 Terminal differentiation markers, adipocytes 2:45 Terrestrial animals, transmission of antimicrobial-resistant organisms 2:419 Terrines 1:529 Tert-butylhydroquinone, warmed-over flavor prevention 1:413 Test and slaughter, infectious disease eradication 2:187 Testicles, as edible by-products 1:110 Testing methods, laboratory accreditation requirements 2:150, 2:150F Testosterone castrated males 2:76 fat synthesis/deposition 2:79–80 muscle growth 2:78–79 pubertal growth 2:53 trenbolone vs. 2:62–63 Testosterone propionate 2:62, 2:62 Test samples see Samples, test Tetrasodium pyrophosphate, as secondary antioxidant 1:414 Texel sheep, hypermuscularity, genetics 1:466 Texture, fish 2:13 Texture, meat 3:267–268, 3:454 aging conditions effect 1:324, 1:339–340 connective tissue properties related to see Connective tissue deviations 1:339–345 intrinsic/extrinsic factors 1:339 dry-cured products 1:427–428 effect of cooking 1:375–376, 1:375F, 1:376F heated meat 1:407–408 see also Meat protein(s), effects of heating measurement method 1:323–324 physical analyses 3:278 role of fat 2:450–451 see also individual meats; Sensory aspects of meat quality; Tenderness Texture development dry/semidry sausages 3:253 fermented sausages 2:4 Textured soy protein (TSP) 1:568 Textured vegetable protein (TVP) 1:568 Texture profile analysis (TPA) 3:278 Texturizing agents, natural curing 1:433 TFA (trans fatty acids) 1:240–241, 2:116 analysis, special procedures 1:209 content of meat 2:116

546

Index

TFA (trans fatty acids) (continued) definition 2:111 see also Fatty acid(s) Thailand, antibiotic growth promotant policy 2:175T Thamnidium, meat spoilage 2:401 Thamnidium elegans 2:401 Thaw drip, packaged frozen fish 3:194 Thawing 2:227–228, 3:202–208 aging and 1:336 cold chain 2:227–228 effect on product quality 3:192 freezing differences 2:227 immersion 2:227 methods, common 2:227–228, 3:205 external heating methods 3:205–206 air thawing see Air thawing microwave 3:206, 3:207 pressure-assisted thawing 3:207 vacuum thawing 3:206–207 water thawing see Water thawing methods internal heating methods 3:207 physical aspects 3:202–203 apparent specific heat around freezing point 3:202–203, 3:203F factors affecting thawing time 3:203, 3:203F frozen fraction vs. temperature 3:202, 3:203F as predrying treatment 1:474 quality aspects 3:203 appearance 3:205 eating quality 3:205 microbial growth 3:203–204, 3:204F water loss 3:204–205 speed 2:227 thermal conductivity 2:227 vacuum 2:227–228 see also Freezing Thawing time, factors affecting 3:203, 3:203F Thaw rigor 1:361–362 Therapeutic lifestyle change (TLC) 2:106 definition 2:105 Thermal anemometers 3:54–55, 3:55F Thermal center 3:62, 3:179 definition 3:57, 3:179 freezing process 3:181, 3:181F locating, errors 3:62, 3:62F causes 3:62, 3:62F Thermal conduction 1:139, 3:196–197 chilling process 3:179 definition 2:225, 2:236, 3:131, 3:184, 3:196 rate of heat flow 3:196 through slab of material 3:196, 3:197F Thermal conductivity 3:463 definition 1:137, 1:471 meat components 3:463, 3:463T meats 1:139 prediction models 3:463 substance composition and 3:463 thawing of meat 2:227 Thermal convection see Convection, thermal

Thermal cycling see Polymerase chain reaction (PCR) Thermal energy, definition 1:508 Thermal loads, meat product chilling/ freezing, process models 2:436, 2:440–441 Thermal processing 1:139 basic effect 1:385 boar taint control 1:99 in canning industry see Canning operations, heat treatment Clostridium botulinum control 1:385, 2:333 conditions, emulsion/batter stability and 1:286 cured meats, chemistry 1:417, 1:419F effect on meat flavor see Flavor development, heat-induced meat flavor; Maillard reaction effect on meat proteins see Meat protein(s), effects of heating methods 1:385–390 surface decontamination see Thermal surface decontamination processes see also specific methods see also Cooking Thermal properties, meat systems 1:139 Thermal radiation see Radiation, thermal Thermal resistance, microorganisms see under Canning Thermal surface decontamination processes 1:389 hot water 1:389 scalding 1:389–390 singeing 1:390 steam 1:389 Thermal technologies, decontamination of processed meat see Processed meat, decontamination Thermochromic materials 3:60–61 Thermocouples 3:57–59, 3:57F basic circuit 3:57, 3:57F external reference (reference junction) 3:57–58, 3:58F multiple temperature measurements 3:57–58, 3:58F internal reference 3:58–59, 3:58F sources of error 3:59 thermopile 3:59, 3:59F use of compensating wires 3:57, 3:58F Thermoelectric sensors 3:51 Thermoformed packaging, definition 3:2, 3:19 Thermoforming, packaging films 3:23 equipment 3:6, 3:6F Thermogenesis brown adipose tissue 2:43 definition 2:43 Thermolysin 2:119 definition 2:118 Thermometers calibration 3:61 errors, types 3:61, 3:61F types 3:57 bimetallic thermometers 3:60 infrared thermometers 3:59–60 liquid-in-glass 3:57

resistance thermometers 3:59, 3:60F thermochromic materials 3:60–61 thermocouples see Thermocouples use 3:61 reading digital displays 3:61 wet and dry bulb thermometers (psychrometers) 3:51 see also Temperature measurements Thermophiles, definition 1:137 Thermopile 3:59, 3:59F Thermoplastic starch 1:568 Thermotolerant Campylobacter 2:382–388 characteristics 2:382, 2:382F control measures 2:385–386 on farms 2:386 during food distribution 2:386–387 butcher shops and retail outlets 2:386–387 restaurants and fast food outlets 2:387 at home 2:387 in meat processing plants 2:386 in poultry houses 2:386 infection see Campylobacteriosis isolation and identification 2:382–383 molecular methods 2:383 multilocus sequence typing analysis of Campylobacter jejuni populations 2:383–384 subspecies identification by pulsedfield gel electrophoresis 2:383 traditional methods 2:382–383 species identification 2:383, 2:383T subspecies identification by serotyping 2:383 mechanism of pathogenicity 2:384 in retail meats, reported occurrences 2:385, 2:385T Thiamine (vitamin B1) 2:127–128 chemical analysis 1:213 functions 2:128 sources and daily requirements 2:128 thermal degradation/decomposition, meat flavor and 1:259, 1:379 Thiazoles, formation via Maillard reaction 1:397, 1:397F Thiazolines, formation via Maillard reaction 1:397, 1:397F Thick filaments 1:155, 1:158F, 1:159, 1:358, 1:359F see also Myofibril(s); Myosin Thin agar layer (TAL) method, Listeria monocytogenes isolation 2:349 Thin filaments 1:155, 1:158F, 1:159, 1:358, 1:359F see also Actin; Myofibril(s); Tropomyosin; Troponin Thiobarbituric acid (TBA) assay 3:395 definition 3:394 2-Thiobarbituric acid-reactive substances (TBARS) 1:412 2-Thiobarbituric acid (TBA) test, lipid oxidation marker 1:412 Thiophenes, formation via Maillard reaction 1:397

Index

Thoracic sticking 1:561–562 3T3-L1 preadipocyte cell line 2:45 Thu¨ringer Leberwurst 1:536 definition 1:530 Thu¨ringer Rostbratwurst 1:537 definition 1:530 Thu¨ringer Rotwurst 1:536–537 definition 1:530 Thu¨ringer sausage 3:245 definition 3:261 fresh 3:264 additives/seasonings 3:263T finished form 3:265T processing 3:265T Thyroidectomy, definition 2:75 Thyroid hormone, thermogenesis 2:44 Thyroid-stimulating hormone receptor 3:361 Thyroxine, lipogenesis 2:51 Tikka 1:539 definition 1:538 Tin, as surface in food production environments/equipment 1:509T Tissues growth, relative order 2:57, 2:57F see also Growth patterns see also specific organs Titin 1:358 a-Tocopherol, warmed-over flavor prevention 1:380–381, 1:413–414 Toggling, leather drying 1:122 Tolerable daily intake (TDI), dioxins and polychlorinated biphenyls 1:498 Tolerable weekly intake (TWI), dioxins and polychlorinated biphenyls 1:498 Tongue as edible by-product 1:107 large see Macroglossia removal, cattle 3:287 washing, cattle slaughter process 3:287 Tonic muscle spasm, definition 3:407 Tonkatsu (Japanese dish) 1:543–544, 1:544, 1:544F Tonsil removal, cattle slaughter process 3:287 TopmaxTM 2:177, 2:179–180 Torr, definition 3:26 Torry meter 2:13 definition 2:8 Torulopsis, lipolysis 2:400 Total body electromagnetic conductivity (TOBEC) 2:484–485 contaminant detection 2:485 Total Enterobacteriaceae counts 2:308, 2:308T, 2:309 Total quality management (TQM) 2:92 Total viable counts definition 2:285 microbial contamination of fresh meat 2:286–287 Totipotent, definition 1:83, 1:84 Touching products (touchers) 3:139 Toughening cold 3:269 cooking and 3:271

definition 3:267 hot 3:269 Toughness, meat see Meat toughness Townsend skinner 1:114 Toxaphene 1:497–498 Toxicity acute/chronic, detrimental effects in humans of veterinary drug residues 3:65 curing agents 1:8, 1:205, 1:205T, 1:437–438 see also specific toxins Toxoplasma gondii 3:35–38T intermediate hosts 3:35–38T equine species 3:40 poultry 3:40 ruminants 3:39 swine 3:40 irradiation effects 2:143 Traceability 1:483 application of genomic technologies 2:41 automated beef carcass cutting/boning systems and 1:37–38 definition 1:480 Trace elements, as environmental contaminants 1:499–500 Trace metal ions, lipid oxidation 1:411 Trace mineral deficiencies, abnormal bone growth 2:81 Trace mineral requirements, poultry 2:464T, 2:466 Track pullers, cattle hide removal 3:287 Trade facilitation, market specifications and 2:232 Traditional animal breeding see Animal breeding, traditional Traditional Chinese meat products (TCMPs) 1:522–526 basic product formulation 1:523 characteristics 1:522–524 coloring 1:523 high salt content 1:523 regional flavors 1:524 sweet taste 1:523 classification 1:524T, 1:525 ham 1:522, 1:523F, 1:524T, 1:525 sausages 1:522, 1:522F, 1:523F, 1:524T Traditional smoke, production 3:140, 3:140F Traditional smoking see Smoking, traditional Trained panel, sensory assessment of meat 3:272, 3:272F Transcription factor, definition 2:49 Transcriptomics 1:13 Transformation, carcinogenesis 2:100 Transforming growth factor-b (TGF-b) superfamily, adipocyte differentiation 2:51 Transgenic animals 1:91 definition 1:92 production methods 1:92–94, 1:93F see also Genetically engineered animals Transglutaminase (meat glue) 1:301 Transmissible spongiform encephalopathies (TSEs) 2:362

547

animal 2:362, 2:363–364 bovine see Bovine spongiform encephalopathy (BSE) chronic wasting disease 2:362, 2:365 human 2:362, 2:365 Creutzfeldt–Jacob disease see Creutzfeldt–Jacob disease (CJD) fatal familial insomnia 2:366 Gerstmann–Stra¨ussler–Scheinker syndrome 2:365–366 kuru 2:365, 2:366F scrapie 2:362, 2:364–365 transmission 2:363 pathogenesis 2:363 Transport of animals 3:97–98 animal behavior during see Animal behavior, during handling and transport cattle 3:96, 3:97–98 definition 3:95 effective temperature 3:97 fasting before 3:96 floor space allowance 3:98 journey times 3:98 loading and unloading 3:96–97, 3:96F, 3:97F, 3:98F pigs 1:367, 3:297 effect of temperature increases 3:97 motion sickness 3:97–98 preparation for 3:95–96 sheep 3:98F vehicle design 3:98, 3:98F Transport of meat/meat products 2:236–243 air transport 2:228, 2:237 cold chain and 2:228 frozen meat 2:236 sea transport 2:236–237 global 2:236 local delivery vehicles 2:238–239 design and operation 2:239 door openings (number of stops) 2:240, 2:241F, 2:242 factors combining to cause problems 2:240–242 heat infiltration 2:239–240 initial food temperature 2:240, 2:241F journey length 2:240, 2:241F problems relating to 2:238–239 standard journey for assessment 2:239, 2:239T testing 2:239 van insulation 2:239, 2:240F overland transport 2:237–238 containers 2:237 cooling of warm meat 2:237 temperatures of vehicles 2:237 refrigeration 2:236, 2:238, 3:188 containers, for sea transport 2:237 conventional forced air systems 2:238 difficulties 2:236 eutectic plates 2:238, 3:188 liquid nitrogen 2:238, 3:188–189 local delivery vehicles 2:238–239 mechanical units 2:238, 3:188 photovoltaics application 2:238

548

Index

Transport of meat/meat products (continued) sea transport 2:236–237 see also Refrigeration; Refrigeration equipment sea transport 2:228, 2:236–237 containers 2:237 duration 2:237, 2:237T storage temperatures 2:237 temperature control during 2:228 in UK 2:236 Transport phenomena canning 1:139 definition 1:137 Transport Quality Assurances program definition 3:168 swine transport 3:172 Transverse process, definition 1:458 Travel, antimicrobial resistance considerations 2:415 Traveler’s diarrhea 2:357–358 Tray overwrap 3:2 machines 3:2, 3:3F see also Overwrapping/overwrap packaging Tray types, overwrapped packages 3:15 Trematodes 3:35–38T see also Parasites Trenbolone (TBOH) in animal production see Trenbolone acetate (TBA) circulating levels 2:63 other steroid effects 2:63–64 definition 2:62 melengestrol acetate and 2:63–64 muscle growth effects 2:65 somatotropin and 2:182 testosterone vs. 2:62–63 Trenbolone acetate (TBA) definition 2:62 estradiol and 2:63 carcass protein 2:65, 2:66F muscle growth 2:65F feed consumption 2:64–65 growth stimulation 2:53 implants circulating levels 2:63 dosage 2:63 muscle growth 2:79 Triacylglycerol lipase 2:44 Triacylglycerols (triglycerides) 1:206, 1:226, 1:227F, 1:239–241 absorption 2:114–115 biosynthesis adipocyte differentiation 2:45 intramuscular vs. subcutaneous adipose tissue 1:223–224 cardiovascular disease and 2:106 definition 1:239, 1:252 hydrolysis 2:47 in meat 2:114 content, effect on cooking 2:114 melting point characteristics 1:240T positional distribution 2:114, 2:114–115 species-specific flavor 1:259 storage 1:353, 2:45, 2:47 nutritional effects 2:80

structure 1:239F see also Fat; Lipid(s) Trichinella 3:35–38T, 3:39, 3:40 Trichinella sprialis, irradiation effects 2:143 Trichinellosis, definition 2:211 Triglyceride see Triacylglycerols (triglycerides) Trimming beef carcasses automated 1:37, 1:38F final trim 3:288 pig carcasses, final trim 3:301 Trimmings 1:109 definition 1:558 Tripe 1:108 Tristmulus definition 2:164 theory of meat color measurement 2:168 Tropical aromatics see Spices Tropical rubs 1:305 Tropocollagen 1:321 Tropomyosin 1:358 definition 1:358 see also Myofibrillar proteins Troponin 1:358 definition 1:358 see also Myofibrillar proteins Troponin C 2:119 ‘Trotters’ (pigs’ feet) 1:109–110 Trout, rainbow see Rainbow trout True error probability (TEP), foreign body detection limits 2:28F, 2:29F, 2:30 True fish definition 3:336 see also Finfish Trueness, definition 1:193, 1:194 Tryptamine, toxicological effects 3:222T Tryptic soy agar (TSA), spoilage bacteria enumeration 2:307–308, 2:308T Tryptose sulfite cycloserine (TSC), Clostridium perfringens isolation 2:336 T-tubular system 1:155, 1:156, 1:157F see also Muscle contraction; Myofibril(s) T-tubule, definition 1:148 Tumblers 3:143–146, 3:144F cure application 1:446 cycle 3:144–145 refrigerated 3:145 types 3:144 vacuum use with 3:144, 3:145 see also Mechanical conditioning Tumbling binding strength–meat temperature relationship 3:145 brine-treated meat 1:422 cooked ham production 2:84 definition 2:82, 3:143 emulsion formation 1:296–297 foamy exudate production 3:143–144, 3:145 meat marination 3:145 time–work intensity relationship 3:144 Tuna 3:337–339T nutritional content 3:336–342, 3:342T

Tunnel ventilation, chicken meat production systems 2:206, 2:207F Turkey(s) 3:370–372 breast muscle size, associated issues 3:370–371 current standard breeds 3:370, 3:371F domestication 3:370 feed additives, beta-agonists 2:177 Turkey fowl, definition 1:235 Turkey meat consumption, trends 3:371–372 mechanically recovered composition 2:272, 2:273T safety 2:274 uses 2:272 nutrient composition 3:371–372, 3:371T pale, soft, exudative (PSE) condition 3:370 production, historical aspects 3:370–371 Turtles 2:196 20S proteasome, analysis in meats 1:216 Twin-screw extruders 1:567, 1:567F Two-dimensional gel electrophoresis, as proteomics tool 3:155 Two-humped Bactrian camel (Camelus bacterium) 3:354 Two-phase packaging 3:7–8 definition 3:7–8 Two-pressure relative humidity generator, hygrometer calibration 3:53 Typing methods Salmonella see under Salmonella Staphylococcus aureus 2:379 thermotolerant Campylobacter see Thermotolerant Campylobacter, isolation and identification Tyramine in raw fermented sausages 3:222, 3:222T as indicator of biogenic amine formation 3:222 toxicological effects 3:222T

U UK see United Kingdom (UK) Ulcers, somatotropin-treated animals 2:184 Ultimate pH (pHu) 1:262 definition 1:329, 1:486, 3:431 effect of preslaughter stress 1:350, 1:350F, 1:351F importance of 1:263 as intrinsic determinant of meat tenderness 3:453T meat tenderness measurement and 3:453T, 3:458 pork muscle 1:339–340 see also pH, meat Ultrasonic anemometers 3:55 Ultrasonic waves, meat tenderization 3:447–448 Ultrasound meat composition measurement 2:482–483, 2:483F pig carcass classification 1:318–319 use in selection programs to improve carcass composition 1:23, 1:23F

Index

Umami taste definition 1:410 meat 1:259 Uncertainty animal health import risk analysis 1:27 definition 1:27 Unconsciousness definition 3:421 induction by gas mixtures mechanisms 3:402 time to onset of unconsciousness 3:402–403 see also Gas stunning see also Stunning Uncooked meat, cooked meat vs., tenderness measurement 3:454–456, 3:454F Uncoupling protein 1 (UCP1) definition 2:43 mouse models 2:44 thermogenesis 2:43–44 Uncured processed meats 1:430 labeling 1:8, 1:431–432 general regulations 1:432 terms 1:432 see also Processed meat(s) Undercooling (supercooling) 3:181, 3:461 Ungulate(s) African see African ungulates definition 2:190, 3:345 Unidentified growth factors (UGFs), meat and bone meal 1:130 United Kingdom (UK) antibiotic growth promotant policy 2:173 game bird consumption 3:347 provincial meat research institutions 2:257–261T Swann Committee 2:173 transport of meat/meat products 2:236 see also entries beginning British United States (US) added water regulations 1:299 animal by-product regulations 1:125 animal welfare legislation 3:103 antibiotic growth promotants 2:174, 2:175T bacon see Belly bacon beef carcass classification/grading 1:309–311 cattle hides, foreign trade in 1:116T eating patterns 2:108T game bird consumption 3:347 game production 3:346 inedible raw material production 1:126–127 leather imports/exports 1:115T marbling to meat palatability relationship 1:254, 1:255T, 1:256T meat demand and supply see Meat pricing systems meat pricing see Meat pricing systems meat production 1:126–127 meat research institutions national 2:255–256T private industrial 2:262–263T provincial 2:257–261T

natural curing see Natural curing nitrite regulations 1:419, 1:430, 1:431T, 1:443 pig carcass classification 3:364–365, 3:364F see also entries beginning US; North American meat products Unknowns, determining 1:190 Unloading 3:96–97, 3:96F, 3:97F poultry 3:303 ramps, design 3:93 Unsaturated fatty acids 1:239–240, 1:240–241 definition 1:130 oxidation 1:411 warmed-over flavor 1:411 species differences in fatty acid composition 1:241 see also Fatty acid(s) Up puller, cattle hide removal 3:286–287 Urinary calculi, male goats 2:476–477 Uropathogenic Escherichia coli 2:357 US see United States (US) US Beef Satisfaction Study, consumer sensory traits 1:256T US Department of Agriculture (USDA) antibiotic use 2:109 beef carcass classification/grading 1:309 fat thickness measurement 1:309, 1:310F final quality grade 1:310–311, 1:311T guaranteed tender 1:311 guaranteed very tender 1:311 kidney, pelvis and heart fat 1:309 lean maturity descriptions 1:311T marbling fat 1:310, 1:310T maturity grades 1:310, 1:310T quality grading 1:310 rib eye fat depth 1:309 skeletal ossification grades 1:309–310, 1:310T yield grades 1:309, 1:309T hormone use 2:109 meat labeling and 2:107 meat pricing and 2:253 US Department of Agriculture Food Safety and Inspection Service (USDA-FSIS), definition 1:555 US Pork Consumer Survey, consumer sensory traits 1:256T Utilitarian, definition 3:108 Utilitarianism, modern 3:108–109 Utility (in economy), definition 2:248, 2:248 UV–Vis spectrometry 1:175

V Vaccenic acid 1:228 Vaccines/vaccination coccidiosis 2:175 Escherichia coli O157:H7 2:360 methanogen 1:73 pigs 2:186, 2:187

549

Vacuum definition 3:26 measurements 3:26, 3:27T secondary chilling/freezing systems 3:187 steam see Steam vacuum Vacuum chamber machines 3:3–4, 3:4F Vacuum clip system 3:3, 3:3F Vacuum dryers 1:475, 1:476F Vacuum-free vacuum pack 3:31 Vacuumize, definition 3:126 Vacuum massaging 3:145 Vacuum mixing 3:127–128 cooked sausage production 3:243 Vacuum packager, capability measurement 3:26 Vacuum packaging 1:301, 3:2–3, 3:18, 3:26–33, 3:79 bag size choice 3:32 benefits 3:26, 3:30 Clostridium botulinum in meats and 2:333 cooked hams 2:85 curing and 3:29 cutting and boning trends 1:463 definition 3:2, 3:19, 3:26 degree of vacuum/pressure 3:26 delay before packaging 3:29 dry-cured hams 2:90–91 effective sealing 3:31 equipment 3:2–3 Pi-Vac 1:454, 3:5, 3:5F, 3:31, 3:446, 3:446F snorkel see Snorkel machines vacuum chamber 3:3–4, 3:4F vacuum clip 3:3, 3:3F vacuum skin pack 3:5, 3:5F films 3:29–30 oxygen permeability 3:29–30 permeability 3:30 physical traits 3:30 properties 3:29–30 fresh meat color 3:27–28, 3:32 fresh meat marketing, commercial difficulties 3:32 frozen meat 3:31–32 gas packaging 3:29 hurdle technology and 2:346–347 larger cuts 3:31 leaks 3:28–29 meat discoloration 3:28–29 microbiology 3:31 myoglobin chemistry 3:26–28 operations 3:30 package traits 3:29–30 pigment layers in meat 3:28 poor vacuum results 3:28–29 product shelf-life 3:31 pumps 3:30 steam evacuation/hot filling 3:30 techniques 3:30–31 warmed-over flavor prevention 1:414 Vacuum-packed meats, spoilage 3:390, 3:391 Vacuum skin packaging machinery 3:5, 3:5F Vacuum thawing 2:227–228, 3:206–207 Vacuum tumbling 3:144, 3:145 Validation, analytical methods 1:178, 1:193

550

Index

veterinary drug residue analysis 1:219–220, 1:220T see also Chemical analysis, standard methods Vane anemometer 3:54, 3:55F Vapor pressure of pure water (po) 1:471–472 definition 1:471 Vapor pressure of water in food (p) 1:471–472 definition 1:471 Variability animal health import risk analysis 1:27 definition 1:27 Vascular infusion, meat tenderization 3:433–436, 3:436F Vat curing, hides 1:116, 1:121T Veal French dishes 1:527–528, 1:528F production 2:478 Vegans 2:135 health benefits 2:138 health risks 2:138 protein deficiency 2:138 Vegetable extracts, retanning 1:121 Vegetable oil, fatty acid composition 1:132T Vegetable tanning 1:121 Vegetarianism 2:135–139 attitudes towards meat 2:136–137 as continuum 2:135 definitions 2:135–136 deterrents to 2:136 ethical motivation 2:135, 2:135–136 gender and 2:138–139 health and 2:135–136, 2:137–138 body mass index 2:138 iron and vitamin deficiency 2:127, 2:138 lipid levels 2:138 omnivore comparison 2:138 protein deficiency 2:138 risks associated 2:138 inconsistencies in eating meat 2:135 motivations 2:135, 2:135–136, 2:136T, 3:282, 3:282T changes over time 2:136 prevalence 2:135 values and 2:137 Vegetarians omnivores vs, health 2:138 perceptions 2:137 reasons for not eating meat 2:135–136, 2:136T, 3:282, 3:282T Velocity, air see Air velocity Velvet antlers 2:193 definition 2:190 Venison consumption 3:348 definition 2:190, 3:345, 3:345–346 nutritional composition 3:348, 3:349T production 3:347–348 New Zealand 3:291 red deer 2:193 see also Deer Ventilation, intensive chicken meat production systems 2:206, 2:206F, 2:207F

Verotoxigenic Escherichia coli (VTEC) see Shiga toxin-producing Escherichia coli (STEC) Verotoxin-producing Escherichia coli see Shiga toxin-producing Escherichia coli (STEC) Vertical cutter/mixers 3:129–130 Vertical paddle massagers 3:143, 3:143F Vertical transmission, definition 2:389 Very-low density lipoproteins (VLDL), fatty acid content 2:47 Vestibulo-ocular reflex assessment of stunning/killing in fish 3:424 definition 3:421 Veterinary-Client-Patient Relationship (VCPR) definition 3:168 swine health 3:170 Veterinary drug residue(s) 1:217, 3:64–66, 3:217–218 analytical procedures see Veterinary drug residue analysis antibiotics 3:65–66 antihelmintics 3:66 consumer risks and 3:218 detrimental effects in humans 3:65 anaphylactic reactions 3:65 antibiotic resistance 3:65 antihelminthic drugs 3:66 chronic and acute toxicity 3:65 growth promoters 3:66 imbalance in human intestinal microflora 3:65 growth promoters 3:66–67 maximum residue limits (MRLs) 1:217 Veterinary drug residue analysis 1:217–221 analytical methodologies 1:218–219 confirmatory methods 1:219–220, 1:219T advantages and disadvantages 1:219T definition 1:217 screening methods 1:219, 1:219T definition 1:217 validation 1:219–220, 1:220T future trends 1:220 sample preparation 1:217–218 sample extraction 1:218 sample storage and pretreatment 1:218 sampling 1:217–218 Veterinary medicinal products (VMPs) antibiotics see Antibiotic(s) beef quality assurance (BQA) guidelines 1:73–74, 3:175T definition 3:214, 3:215–216 environmental impacts 1:506 premarketing authorization 3:215–216 Vibrio, Wiltshire bacon cover brines 1:61 Vicugna pacos see Alpaca (Vicugna pacos) Vicun˜a (Vicugna vicugna) 2:193, 3:354 Video image analysis (VIA) assessment of adherence to product specifications 2:234 definition 1:307 meat composition 2:482, 2:482F meat tenderness measurement 3:458

Vienna Bologna (fleischwurst) 3:243 Vienna sausage 3:245, 3:260 production process 2:93F failure mode and effects analysis 2:97, 2:97F, 2:98 hazard analysis and critical control point 2:96, 2:96T Vindaloo see Goan vindaloo Vinegar, traditional method of making biltong 1:515–516 Violative residues, definition 3:173 Violet red bile glucose agar (VRBGA), total Enterobacteriaceae counts 2:308T, 2:309 Viremia, definition 2:389 Virginiamycin bans 2:173–174 small intestine microbial activity changes 2:173 Virulence, definition 2:405 Virulence factors Aeromonas 2:318 definition 2:289 Listeria monocytogenes 2:352–353 Virulence genes, Aeromonas, distribution 2:321 Virulence mechanism, Salmonella 2:371 Virus(es) definition 2:204 foodborne 2:389–394 outbreaks 2:389 see also Caliciviruses; Hepatitis E virus; Rotavirus survival in food caliciviruses 2:393 hepatitis E virus 2:390–391 rotavirus 2:393–394 zoonotic transmission caliciviruses 2:391–393 hepatitis E virus 2:390 rotavirus 2:393 see also specific viruses Visceral, definition 2:135 Visceral parasites, land-farmed animals see under Parasites Vision, effect on animal movement 3:85–86, 3:96–97, 3:98F Visual assessment, meat color 2:170–171 Visual evoked responses (VERs), mechanical stunning physiology 3:413–414, 3:414T Visual impact, at point of sale 3:268 Vitamin(s) deficiencies 2:449 abnormal bone growth 2:81 definition 1:440–441 human diet 2:121, 2:126–127 in meat, chemical analysis 1:212 fat-soluble vitamins see under Fatsoluble vitamins water-soluble vitamins see under Watersoluble vitamins nitrite as 1:440–441 in poultry production systems, definition 2:204 requirements

Index

pigs 2:459, 2:460T poultry 2:464T, 2:466 Vitamin A beef marbling 1:314–315 human diet 2:121 yellow fat, beef 3:334 Vitamin B1 see Thiamine Vitamin B2 (riboflavin) 2:128 in meat, chemical analysis 1:213 sources and daily requirements 2:128 Vitamin B3, muscle fiber types and 2:447 Vitamin B6 2:127 homocysteine reduction 2:127 in meat, chemical analysis 1:213 Vitamin B9, human diet 2:121 Vitamin B12 (cyanocobalamin) 2:127 deficiency, vegetarians 2:127, 2:138 functions 2:127 homocysteine reduction 2:127 human diet 2:121, 2:127 in meat 2:127 chemical analysis 1:213–214 sources 2:127 Vitamin B group 2:127 Vitamin D 2:126–127 as animal-derived nutraceutical 2:133–134 deficiency 2:127 human diet 2:121 in meat/meat products 2:126 sources 2:126, 2:126–127 supplements 2:127 synthesis 2:126–127 Vitamin D3 (cholecalciferol) 2:133–134 Vitamin E, human diet 2:121 Vitamin E supplementation, warmed-over flavor prevention/minimization 1:380–381, 1:413–414 Vitek system, yeast identification 2:396 Vocalizations, stress and 3:84–85, 3:100 Volatile compounds dry fermented sausages 3:252, 3:254T generated during cooking/in cooked meat 1:377–378, 1:378F, 1:391, 1:392F desirable meaty aromas of cooked meat and 1:381 see also Flavor(s); Flavor development; Maillard reaction Volatile fatty acids (VFAs), definition 2:471 Volatiles definition 1:252 flavor aromatics 1:258, 1:258–259 Voltage, definition 1:486 Voltammetry 1:175 Volume 3:460 measurement 3:460 Volumetric analysis 1:174 ‘Vrinnebiltong’ 1:515 V-track restrainers, cattle stunning 3:284–285

W Wagyu beef, fat levels 2:114 Wagyu cattle, propensity to fatten 3:332 Walking beam, definition 3:123

Walking beam systems 3:132–133, 3:133F Warm boning 1:453 operations 1:455 see also Hot boning Warmed-over flavor (WOF) 1:410–415, 3:394, 3:396–397 chemical analysis 1:411–412 concerns over 1:410 cooking method in 1:413 definition 1:416, 3:399 development 1:259–260 enzymatic degradation 1:411 freezing effects 1:410 lipid oxidation 1:410–411 meat quality and 1:413 off flavor tastes 1:410 older meat 1:413 preventive/minimization strategies 1:412–413 flavor masking 1:414–415 handling 1:413 packaging 1:414 primary antioxidants 1:413, 3:396 vitamin E supplementation 1:380–381 protein oxidation 1:411 sensory analysis 1:411–412 terminology 1:411–412, 1:412T Warming lights, warmed-over flavor 1:413 Warm smoking 3:321 definition 3:321 see also Smoking, traditional Warner–Bratzler shear 3:453–454, 3:455T definition 1:307 see also Tenderness measurement Warner–Bratzler shear force 3:278 definition 2:37 values Brahman cattle, genetic studies 2:37–38 marbling 1:254 Warthog (Phacochoerus africanus) 3:351 carcass weight 3:351–352 fatty acid profile 3:352, 3:354T meat proximate composition 3:354T pale, soft, and exudative meat 3:352 Washing, dry-cured ham production 2:89 Waste management, Europe 2:157–163 animal by-products 2:158–159, 2:162 category 1 material 2:158–159 category 2 material 2:159 category 3 material 2:159–160 disposal and recycling 2:161 biowaste 2:157–158, 2:157F reutilization pathways 2:158F hygiene and 2:161–162 legal background 2:157 municipal solid waste 2:157 sewage sludge 2:158 waste treatment 2:160 anaerobic digestion processes 2:160–161, 2:162F composting see Composting disposal and recycling of animal by-products 2:161 Waste recycling see Recycling Waste reuse 2:157

551

Water added to meat see Added water content, meat see Moisture content immobilized 1:274, 1:363 muscle tissue 1:274 arrangement of interfilamental water 1:274, 1:274F pure, pressure–temperature phase diagram 1:475–476, 1:476F requirements see Water requirements sorption isotherm 1:472, 1:472F use in curing 1:443 Water activity (aw) 1:471–472 biltong 1:516 Clostridium botulinum control in meats 2:333 definition 1:137, 1:425, 1:471, 1:515, 1:518, 1:550, 2:87, 2:236, 2:345, 3:50, 3:50–51, 3:184, 3:248, 3:388 dry/semidry sausages 3:250 influence on microbial growth 3:78–79, 3:78T measurement 3:50–51 use of hygrometers 3:52, 3:52F meat products, examples 1:472 reduction methods, drying see Drying relationship with water content 1:472, 1:472F Water activity meters, moisture content measurement 3:53, 3:53F Water availability, lairage 3:99 Water bath cooking 1:330, 1:373 Water binding see Muscle proteins, functionality Water-binding capacity definition 2:164 muscle fiber types and 2:446 see also Water-holding capacity Water buffalo 3:355 classification 3:355 production systems 2:192–193 slaughter process 3:291 Water buffalo meat composition 3:356 quality characteristics 3:356 value-added products 3:355 Water compartments, in muscle foods 1:268 see also Muscle proteins, functionality Water content see Moisture content Waterers, chicken meat production systems 2:208 Water fraction definition 3:315 smoke condensates 3:316 Water-holding capacity 1:236–237, 1:274–282, 2:164–165 contractile proteins (actin and myosin) and 1:274–275 cation shielding of Mg-ATP and its effect on water held between proteins 1:275, 1:276F divalent and monovalent cation effects on free water 1:274–275, 1:275F effect of hydroxyl ion shielding of calcium–magnesium–ATP on water located in myofibril 1:275, 1:276F

552

Index

Water-holding capacity (continued) effect of neutral and low pH on myofibrillar swelling 1:275, 1:277F definition 1:274, 1:274, 2:164, 2:164, 3:70 factors affecting 1:237, 1:237T, 1:363–364, 1:364F, 2:164–165 ageing 1:278 ammonium hydroxide 1:280 calpain 1:280–281 freezing rate 3:192–193, 3:193F heating 1:405–406 high-pressure processing 1:279–280 ionic strength 1:279, 1:279T, 1:280T mincing 2:423, 2:423T pH 1:257, 1:257F, 1:275–277, 1:277F phosphates 1:278–279, 1:299 postmortem glycolysis rate 1:278 rigor 1:277–278 salt (NaCl) 1:278 temperature 1:278 measurement 2:165–166, 2:493 indirect methods 2:167 cook yield 2:167 protein solubility 2:167 methods applying external force 2:166–167 heat application (cooking loss) 2:167 high-speed centrifugation 2:166 low-speed centrifugation 2:166, 2:166F press method/compression 2:166 rapid filter paper method 2:166, 2:167F methods applying no external force gravimetric method 2:165, 2:165F subjective scoring of exudate 2:166 weep/purge method 2:165 meat extenders 1:1–2 muscle fiber types and 2:446 nonmeat proteins 1:289–290 pork 3:365–366 see also Drip loss; Moisture content; Muscle proteins, functionality Water loss, meat thawing and 3:204–205 Water medication programs, pigs 2:187 Water requirements feedlot cattle, calculation 2:479, 2:479T pigs 2:459 poultry 2:466 Water-soluble vitamins in meat, chemical analysis 1:213 folates 1:214 riboflavin (vitamin B2) 1:213 thiamine (vitamin B1) 1:213 vitamin B6 1:213 vitamin B12 (cyanocobalamin) 1:213–214 see also specific vitamins Water sprays, chilling of meat see Chilling; Spray chilling Water thawing methods 3:206 immersion thawing 3:206, 3:206F spray thawing 3:206, 3:206F Water transport, during drying of solid foods 1:473, 1:473F Wazwan meats see Kashmiri wazwan meats

Weaner, definition 2:190 Weaning, pigs 2:455 Weasand, tie and separation, cattle slaughter process 3:287 Weasand rod 3:287 Weep measurement 2:165 see also Drip Weighing, live animals pigs 3:297 poultry 3:303 Weight-reducing diet 2:109 Weinberg casting pen 3:211–212 definition 3:209 WeiXer Schwartenmagen, definition 1:530 Weisswurst 3:246 Welfare, animals see Animal welfare Welfare issues finfish 3:342–343 shellfish 3:386 see also Animal welfare Welfare Qualitys 3:95, 3:112 welfare criteria 3:102, 3:112T Western blotting, meat tenderness measurement 3:458 Westfa¨lischer Knochenschinken 1:533 definition 1:530 Wet aging 1:337, 2:228, 3:270 see also Aging, meat Wet bulb depression 3:51 definition 3:50 Wet bulb thermometers 3:51 oven temperature measurement 3:136 Wet markets 2:244–247 future of 2:246–247 Hong Kong see Hong Kong market forces 2:245 meat stalls 2:244 modern 2:246, 2:246F, 2:247F poultry stalls 2:244–245 public health hazards 2:245–246 Singapore see Singapore strengths 2:245 weaknesses 2:245 Wet rendering 1:128 Wet-sensor temperature cooking processes effect on drying/heating rates 3:136–137 measurement 3:136 definition 3:131 Wheat proteins, use in comminuted meat products 1:293–294 Whelks 3:385 Whey, use as meat extender 1:4 Whey proteins, use in comminuted meat products 1:291–292 Whisker molds 2:401 White adipose tissue (WAT) 2:44–45 definition 2:43 de novo lipogenesis 2:45–47 development, newborn mammals 2:44–45 differentiation 2:44–45, 2:45 hyperplasia 2:45 hypertrophy 2:44–45, 2:45 processes 2:44–45

functions 2:44–45 thermoinsulation 2:44–45 White boudin 1:529 White hots (cooked bratwurst) 3:260 White river crawfish 3:381 White sausage see Bockwurst White scraping, pig carcasses 3:299–300 White spot 2:401 Whole grain feeding, poultry 2:468 Whole hog sausage 3:261 Whole-muscle jerky 1:555 Whole muscle product manufacture, natural curing procedures 1:434 Wholesale cuts, definition 3:13 Whole spices 1:304–305 Wiener 1:534–535, 3:243–245, 3:260 definition 1:530 Wild birds, transmission of antimicrobialresistant organisms 2:419–420 Wild boar 3:350–351 carcass yields 3:351 dressed weights 3:351 fatty acid profile 3:351, 3:353T as intermediate hosts for parasites 3:39 Wild game, definition 3:345, 3:345 Wildlife, role in transmission of antimicrobial-resistant bacteria 2:417, 2:418T Wild (capture) production, finfish 3:336, 3:337–339T Wild suids 3:349–352 Wild water buffalo (Bubalus arnee) 2:192, 3:355 Wiltshire bacon 1:58–63, 1:447 carcass trimming 1:58 color 1:62 color problems 1:62 cover (tank) brines 1:58–59 advisory standards 1:62T microbiology 1:61 cuts 1:59F, 1:62–63 definition 3:388 flavor characteristics 1:62 flavor development 1:62 historical aspects 1:58 injection brines 1:58–59, 1:61F advisory standards 1:61T microbiology 1:60–61 microbial spoilage 1:61–62 microbiology 1:60–61 packaged product 1:61 oxidation 1:62 processing/production 1:58–59, 1:60F brine ingredients 1:59 curing brine composition 1:58–59 immersion brine care 1:59 maturation period 1:59 production codes of practice 1:58 sides see Wiltshire sides smoking 1:62–63 surface spoilage 1:61–62 Wiltshire curing definition 1:58 see also Brine curing

Index

Wiltshire sides cutting 1:59F, 1:62–63 packaging 1:62 transport 1:62 WISPs (nutrient analysis software) 2:124 Withdrawal time, definition 3:168 Wnt-signaled transduction, myogenic differentiation 2:50 Wolssverilne skinner 1:114 Women reasons for reduced meat consumption 3:282, 3:282T semivegetarians, meat hierarchy among 3:280, 3:280T Wood as foreign body in meat 2:23, 2:23T as surface in food production environments/equipment 1:509T Wood smoke 3:322 composition 3:322, 3:322T definition 3:321 generation 3:322 health hazards associated with 3:324 see also Polycyclic aromatic hydrocarbons (PAHs); Smoking, traditional Working animals, cattle as 2:213–214, 2:214F World Organization for Animal Health (OIE) animal by-product uses 1:126 animal welfare definition 3:102 definition 2:211, 2:231 Terrestrial Animal Health Code, international trade risk analyses 1:28 traceability requirements 1:483 World Trade Organization (WTO) Agreement on the Application of Sanitary and Phytosanitary Measures (SPS Agreement) imported commodities sanitary measures 1:28 see also SPS Agreement 1995 definition 1:480 Wound botulism 2:330 Wrapped products chilled 2:229 display cabinets 3:189, 3:189F frozen, display cabinets 3:189, 3:189F Wrapping 3:2 residues from 3:224 see also Overwrapping/overwrap packaging

X X-ray methods/systems dual-energy see Dual-energy X-ray (DXA) systems fat analysis 1:182T, 1:183 foreign body detection see under Foreign bodies meat composition measurement see Online measurement, meat composition

Y Yakitori (Japanese dish) 1:544, 1:544F Yeast(s) 2:395–404 acceptable ranges in food 2:397, 2:400T cell morphology 2:395 colony appearance 2:397 enumeration 2:396–397 slides with grids 2:397 viable cells 2:397 fermented meat products 2:402 food safety issues 2:402 identification 2:396–397 commercial rapid systems 2:396 criteria 2:396 importance 2:395 lipolytic activity 2:400 in meats beneficial aspects 2:401–402 importance of 2:397–401 occurrence 2:397–401 quality, effects on 2:400 sensory properties 2:400 spoilage 2:402, 3:392–393, 3:392T spores 2:395 Yeast-based ingredients, use in comminuted meat products 1:294 Yeast extract, warmed-over flavor prevention 1:413 Yellow fat, beef 3:334 Yellow grease 1:133 definition 1:133 fatty acid profile 1:131T, 1:133 specifications 1:133, 1:133T uses 1:133 Yersinia detection/enumeration 2:315 enrichment procedure 2:313–314T plating procedures 2:313–314T pre-enrichment procedure 2:313–314T recovery/differentiation agents 2:312T Yersinia enterocolitica 2:20, 2:405–411 biotypes 2:405–406, 2:406T characteristics 2:405–407, 2:405F control measures 2:410 epidemiology 2:409–410 human infection see Yersiniosis isolation and identification 2:408–409 enrichment 2:409 identification 2:409 isolation 2:409 sample preparation 2:409 tests of pathogenicity 2:409 outbreaks 2:309 pathogenicity mechanism 2:407–408 tests 2:409 Yersinia enterocolitica-like species 2:405, 2:406T Yersiniosis 2:19–20, 2:407 clinical presentation 2:20, 2:407 complications 2:407

553

incidence 2:20 treatment 2:407 see also Yersinia enterocolitica Yukhoe (Korean dish) 1:548–549, 1:548F

Z Z-disks 1:157F, 1:158F, 1:159, 1:163F, 1:359F definition 3:443 meat toughness and 1:257 see also Myofibril(s) Zebu cattle (Bos indicus) 3:330, 3:330F definition 1:235 meat tenderness 3:334 temperament 3:331 yellow fat 3:334 Zeranol, estradiol vs. 2:62–63 Zero error, thermometer calibration 3:61, 3:61F Zero-order kinetics, definition 2:8 Zilpaterol (Zilmaxs) 2:177, 2:178, 2:178F, 2:179, 2:180 approval 2:66–67 beef tenderness 2:68 carcass fat reduction 2:80 definition 2:62 growth promotion 2:53–54 mechanism of action 2:67 Zinc 2:125–126 absorption promoted by meat 2:126 human diet 2:121 levels from meat 2:125 meat sources 2:126 Zinc bacitracin, small intestine microbial activity changes 2:173 Zinc finger nucleases (ZFNs), in transgenic animal production 1:93–94 Zingibain 3:441 Zoonoses/zoonotic disease African ungulates 3:349 definition 2:17, 2:367, 2:417, 3:345 foodborne see Foodborne zoonoses parasitic drivers for transmission 3:41 eating habits 3:41 public health impacts 3:41 see also Parasites see also specific diseases Zoonotic bacteria 2:413, 2:417, 2:419 antibiotic resistance see under Antibiotic resistance definition 2:412 target pathogen vs. 2:413 Zoonotic transmission definition 2:389 viruses see Virus(es), zoonotic transmission z-value, heat treatment 1:140 Zwei-Punkt (ZP) procedure 1:318, 1:318F Zygospores 2:395 Zygote, definition 1:92