Handbook of fermented meat and poultry [2nd edition] 9781118522691, 1118522699, 9781118522653, 1118522656, 9781118522677, 1118522672, 9781118522684, 1118522680

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Handbook of Fermented Meat and Poultry

Handbook of Fermented Meat and Poultry Second Edition Editor-in-Chief Fidel Toldrá Instituto de Agroquímica y Tecnología de Alimentos (CSIC), Paterna, Valencia, Spain

Consulting Editor Y. H. Hui Science Technology System, West Sacramento, CA, USA

Associate Editors Iciar Astiasarán Department of Food Science, Nutrition and Physiology, University of Navarra, Pamplona, Spain Joseph G. Sebranek Food Science and Human Nutrition, Iowa State University Ames, IA, USA Règine Talon INRA, UR454 Microbiologie, Saint-Genès Champanelle, France

This edition first published 2015 © 2015 by John Wiley & Sons, Ltd Registered office: John Wiley & Sons, Ltd, The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK Editorial offices: 9600 Garsington Road, Oxford, OX4 2DQ, UK The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK 111 River Street, Hoboken, NJ 07030-5774, USA For details of our global editorial offices, for customer services and for information about how to apply for permission to reuse the copyright material in this book please see our website at www.wiley.com/wiley-blackwell. The right of the author to be identified as the author of this work has been asserted in accordance with the UK Copyright, Designs and Patents Act 1988. 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, except as permitted by the UK Copyright, Designs and Patents Act 1988, without the prior permission of the publisher. Designations used by companies to distinguish their products are often claimed as trademarks. All brand names and product names used in this book are trade names, service marks, trademarks or registered trademarks of their respective owners. The publisher is not associated with any product or vendor mentioned in this book. Limit of Liability/Disclaimer of Warranty: While the publisher and author(s) have used their best efforts in preparing this book, they make no representations or warranties with respect to the accuracy or completeness of the contents of this book and specifically disclaim any implied warranties of merchantability or fitness for a particular purpose. It is sold on the understanding that the publisher is not engaged in rendering professional services and neither the publisher nor the author shall be liable for damages arising herefrom. If professional advice or other expert assistance is required, the services of a competent professional should be sought.

Library of Congress Cataloging-in-Publication Data Handbook of fermented meat and poultry / editor-in-chief, Fidel Toldrá ; associate editors, Y.H. Hui, I. Astiasarán, J.G. Sebranek, & R. Talon.—2nd edition. pages cm Includes bibliographical references and index. ISBN 978-1-118-52269-1 (hardback) 1. Fermented foods–Handbooks, manuals, etc. 2. Meat–Preservation–Handbooks, manuals, etc. 3. Fermentation–Handbooks, manuals, etc. I. Toldrá, Fidel. TP371.44.H357 2015 664′ .024—dc23 2014024540

A catalogue record for this book is available from the British Library. Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic books. Cover image: Fresh spicy Pepper Salami ©iStock.com/sasimoto; Spanish chorizo ©iStock.com/THEPALMER; Tasty meat sausages during manufacturing process before sale ©iStock.com/blanscape; Asia sausage in market - red sausage ©iStock.com/seagames50; Close up Salami ©iStock.com/Juanmonino; Salami sausages in the market ©iStock.com/tomazl Set in 9.25/11.5pt MinionPro by Laserwords Private Limited, Chennai, India.

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Contents List of Contributors, xvii Preface, xxi

Part I Meat Fermentation Worldwide: Overview, Production, and Principles,

1

1 Dry-Fermented Sausages and Ripened Meats: An Overview, 3 Fidel Toldrá and Y.H. Hui

1.1 Introduction, 3 1.2 Fermented sausages and ripened meats around the world, 3 1.3 The importance of fermented sausages, 5 Acknowledgement, 6 References, 6 2 Production and Consumption of Fermented Meat Products, 7 Herbert W. Ockerman and Lopa Basu

2.1 Introduction, 7 2.2 Current products, 7 2.3 The Future, 10 References, 10 3 Principles of Meat Fermentation, 13 Eero Puolanne and Esko Petäjä-Kanninen

3.1 3.2 3.3 3.4 3.5 3.6

Introduction, 13 Fermentation, 14 Factors influencing fermentation, 15 Proteolysis, 15 Lipolysis, 15 Antagonistic effects, 16 References, 16 4 Principles of Curing, 19 Ronald B. Pegg and Karl O. Honikel

4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8

Definition of curing, 19 History of curing, 19 Legislation, 20 Chemistry of nitrite and nitrate, 20 Nitrite and nitrate in meat products, 22 Nitrosomyoglobin (NOMb), 27 N-nitrosamine formation, 28 Conclusion, 29 References, 29 5 Principles of Drying, 31 Raúl Grau, Ana Andres, and José M. Barat

5.1 5.2 5.3 5.4

Introduction, 31 Basic principles of drying, 31 Hurdle technology applied to dried meat and poultry products, 32 Fundamentals of the drying of meat and poultry products, 34

v

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Contents

5.5 Drying kinetics modeling, 35 5.6 Air conditioning and circulation in meat drying, 35 References, 36 6 Principles of Smoking, 39 Zdzisław E. Sikorski and Izabela Sinkiewicz

6.1 6.2 6.3 6.4 6.5 6.6 6.7

Introduction, 39 Wood-smoke composition, 39 The preserving effect, 40 The flavoring effect, 41 Benefits and risks, 42 Food engineering approach, 43 Smoking procedures, 45 References, 45

Part II Raw Materials,

47

7 The Biochemistry of Meat and Fat, 49 Fidel Toldrá and Milagro Reig

7.1 7.2 7.3 7.4 7.5

Introduction: muscle structure, 49 Meat composition, 49 Muscle proteases and lipases, 51 Adipose tissue lipases, 52 Post mortem muscle metabolism and quality, 53 References, 53 8 Ingredients, 55 Jorge Ruiz and Trinidad Pérez-Palacios

8.1 8.2 8.3 8.4 8.5

Introduction, 55 Lean, 55 Fat, 56 Factors affecting the suitability of lean and fat for processing, 56 Other ingredients, 62 References, 65 9 Additives, 69 Pedro Roncalés

9.1 9.2 9.3 9.4 9.5 9.6 9.7 9.8 9.9

Introduction, 69 Acids and related additives, 69 Antioxidants, 70 Colorants, 70 Emulsifiers, 71 Flavor enhancers, 72 Flavoring agents, 73 Preservatives, 74 Multipurpose additives: phosphates, 75 References, 76 10 Spices and Seasonings, 79 Suey Ping Chi and Yun Chu Wu

10.1 10.2 10.3 10.4

Introduction, 79 Ethnic preferences, 79 Commonly used spices in processed meats, 80 Botanical properties, 80

Contents

10.5 10.6 10.7 10.8 10.9 10.10

Product forms and appearances, 80 Chemical properties, 80 Quality standards, 81 Sensory properties, 82 Applications in fermented meat processing, 87 Conclusion, 87 References, 87 11 Casings, 89 Yun Chu Wu, Suey Ping Chi, and Souad Christieans

11.1 11.2 11.3 11.4 11.5 11.6 11.7

Introduction, 89 Natural casings, 89 Artificial casings, 93 Regulatory compliance, 94 Handling casings, 95 Quality determination, 95 Conclusion, 96 References, 96

Part III Microbiology and Starter Cultures,

97

12 Microorganisms in Traditional Fermented Meats, 99 Sabine Leroy, Isabelle Lebert, and Régine Talon

12.1 12.2 12.3 12.4 12.5

Introduction, 99 Traditional sausage manufacture, 99 Description of ecosystems, 100 Identification of technological microbiota, 102 Conclusion, 103 References, 103 13 The Microbiology of Fermentation and Ripening, 107 Margarita Garriga and Teresa Aymerich

13.1 13.2 13.3 13.4 13.5 13.6

Introduction, 107 The manufacture of fermented sausages, 107 Technological microflora, 108 Spoilage microflora, 111 Foodborne pathogens, 111 Starter cultures, 111 References, 112 14 Bacteria, 117 Pier Sandro Cocconcelli and Cecilia Fontana

14.1 14.2 14.3 14.4 14.5

Introduction, 117 Bacterial starter cultures used for fermented meats, 117 Starter cultures: technological advantage in the meat environment, 120 Safety of selected meat starter-culture bacteria, 123 Conclusion, 124 References, 124 15 Bioprotective Cultures, 129 Graciela Vignolo, Patricia Castellano, and Silvina Fadda

15.1 Introduction, 129 15.2 Starter cultures for meat fermentation, 129 15.3 Competitiveness of starter cultures, 131

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15.4 Bioprotective cultures for fermented meat products, 132 15.5 Conclusion, 135 References, 135 16 Yeasts, 139 M.D. Selgas and M.L. Garc´ıa

16.1 16.2 16.3 16.4

Introduction, 139 Presence of yeasts on meat sausages, 139 Role of yeasts in meat products, 140 Yeast starter cultures, 144 References, 144 17 Molds, 147 Elettra Berni

17.1 17.2 17.3 17.4 17.5 17.6

Introduction, 147 Fungal contamination in ripening environments, 147 Fungal starter cultures, 148 Lipolytic and proteolytic activity of starter cultures, 149 Growth and competitiveness of starter cultures, 149 Conclusion, 151 References, 151 18 Probiotics, 155 Keizo Arihara

18.1 18.2 18.3 18.4 18.5

Introduction, 155 Probiotics and probiotic foods, 155 Probiotics and meat products, 156 Prebiotics and synbiotics, 157 Conclusion, 158 References, 158 19 The Genetics of Microbial Starters, 161 Jamila Anba-Mondoloni, Marie-Christine Champomier-Vergès, Monique Zagorec, Sabine Leroy, Emilie Dordet-Frisoni, Stella Planchon, and Régine Talon

19.1 19.2 19.3 19.4 19.5

Introduction, 161 Chromosome elements, 161 Plasmids, 163 DNA transfer and genetic tools, 163 Post-genomics studies, 164 References, 165 20 The Influence of Processing Parameters on Starter Culture Performance, 169 F. Leroy, T. Goudman and L. De Vuyst

20.1 20.2 20.3 20.4 20.5 20.6 20.7 20.8 20.9 20.10

Introduction, 169 Influence of raw materials, 169 Influence of temperature, 170 Influence of added fermentable carbohydrates, 171 Influence of salting and drying, 172 Influence of curing agents, 173 Influence of spices, 173 Influence of sausage caliber, 173 Influence of maturation and molding, 173 Conclusion, 174 Acknowledgments, 174 References, 174

Contents

21 Methodologies for the Study of Microbial Ecology in Fermented Sausages, 177 Valentina Alessandria, Kalliopi Rantsiou, Paola Dolci, and Luca Cocolin

21.1 Introduction, 177 21.2 Molecular approaches to the study of microbial ecology in fermented sausages, 178 21.3 Culture-independent methods, 178 21.4 Definition of the microbial ecology in fermented sausages by culture-independent methods, 180 21.5 Culture-dependent methods, 182 21.6 Definition of the microbial ecology in fermented sausages by culture-dependent methods, 183 21.7 Conclusion, 184 References, 185

Part IV Sensory Attributes, 189 22 Sensory Analyses-General Considerations, 191 Asgeir Nilsen, Marit Rødbotten, Ken Prusa, and Chris Fedler

22.1 Introduction, 191 22.2 Sensory methods, 191 22.3 Sensory analysis of fermented meat products, 192 References, 194 23 Color, 195 Jens K.S. Møller, Sisse Jongberg, and Leif H. Skibsted

23.1 23.2 23.3 23.4 23.5 23.6 23.7 23.8

Introduction, 195 Color-forming compounds, 195 Chemistry of meat color, 195 Influence of fermentation parameters on color, 197 Bacterial role in meat color, 199 Natural and organic cured meat, 200 Color stability of cured meat products, 201 Conclusion, 203 Acknowledgment, 203 References, 203 24 Texture, 207 Shai Barbut

24.1 24.2 24.3 24.4 24.5 24.6 24.7 24.8

Introduction, 207 Texture of commercial products, 207 Texture development during fermentation, 207 Texture development during ripening, 210 Texture development during cooking (nondried/semidried), 211 Effects of processing parameters, 213 Effects of product modification with non-meat ingredients, 214 Conclusion, 214 References, 215 25 Flavor, 217 Mónica Flores and Alicia Olivares

25.1 25.2 25.3 25.4

Introduction, 217 Precursor generation reactions of fermented meat flavor, 217 Volatile compound generation reactions, 218 Extraction and identification of volatile compounds, 218

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25.5 Elucidation of aroma active compounds, 220 25.6 Relevance of volatile compounds in fermented meats, 220 References, 224

Part V Product Categories: General Considerations, 227 26 Composition and Nutrition, 229 Daniel Demeyer

26.1 26.2 26.3 26.4 26.5

Introduction, 229 Nutrient supply from meat and meat products, 229 Meat and meat products in healthy nutrition, 232 Recommended meat intakes, 233 Effects of fermentation on the nutritional and health properties of meat, 234 References, 236 27 Functional Dry-Fermented Sausages, 241 Diana Ansorena and Iciar Astiasarán

27.1 27.2 27.3 27.4 27.5 27.6 27.7

Introduction, 241 Modification of the mineral content in dry-fermented sausages, 241 Fat modifications in dry-fermented sausages, 243 Incorporation of fiber into dry-fermented sausages, 245 Use of dry-fermented sausages as probiotics, 246 Incorporation of vitamins, 246 Conclusion, 247 References, 247 28 Low-Sodium Products, 251 Fidel Toldrá and José M. Barat

28.1 28.2 28.3 28.4

Introduction, 251 Relevance of salt in fermented meats, 251 Strategies for sodium reduction, 252 Effects of sodium reduction on quality and safety, 253 References, 254 29 International Standards: United States, 259 Elizabeth Boyle and Melvin C. Hunt

29.1 29.2 29.3 29.4 29.5

Introduction, 259 US regulatory process, 259 Regulatory definitions and specifications, 260 HACCP options, 261 Validation, 261 References, 261 30 International Standards: Europe, 263 Reinhard Fries

30.1 30.2 30.3 30.4 30.5

Introduction, 263 Quality, 263 Microbiological safeguarding in food chains, 266 Generating microbiological data in practice, 268 Microbiological criteria for foodstuffs in Reg. (EC) 2073/2005, 270 References, 270 31 Packaging and Storage, 273 Byungrok Min and Dong Uk Ahn

31.1 Introduction, 273

Contents

31.2 31.3 31.4 31.5

Part VI

Functions of food packaging, 273 Packaging materials, 274 Packaging systems, 276 Storage, 279 References, 279

Semidry-Fermented Sausages, 281

32 US Products-Semidry Sausage, 283 Robert E. Rust

32.1 32.2 32.3 32.4 32.5

Introduction, 283 Methods of acidification, 283 Food safety, 283 Manufacturing processes, 284 Different types of US semidry sausage, 285 Reference, 285 33 European Products, 287 Friedrich-Karl Lücke

33.1 Introduction, 287 33.2 Definition of “semidry-fermented sausage” in Europe, 287 33.3 General remarks on the manufacture of European-style semidry-fermented sausages, 288 33.4 Types of European-style semidry-fermented sausage, 290 33.5 Safety and stability, 291 33.6 Conclusion, 291 References, 291

Part VII Dry-Fermented Sausages, 293 34 US Products-Dry Sausage, 295 Robert Maddock

34.1 34.2 34.3 34.4 34.5

Introduction, 295 European versus US products, 295 Definitions, 295 US manufacturing processes for dried sausages, 296 Basic formulations and processes for selected large-diameter dried sausages, 297 34.6 Safe production of dried sausages in the United States, 298 34.7 Process control points for dried sausage manufacturing, 298 References, 299 35 Mediterranean Products, 301 ˜ Eva Hierro, Manuela Fernández, Lorenzo de la Hoz, and Juan A. Ordónez

35.1 35.2 35.3 35.4 35.5

Introduction, 301 Production of Mediterranean dry-fermented sausages, 301 Changes during ripening of Mediterranean dry-fermented sausages, 303 Innovation in Mediterranean dry-fermented sausages, 306 Conclusion, 308 References, 309 36 Northern European Products, 313 Askild Holck, Even Heir, Tom C. Johannessen, and Lars Axelsson

36.1 Introduction, 313

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Contents

36.2 36.3 36.4 36.5

Characteristics of Northern European sausages, 313 Sausages of Central Europe, 316 Sausages of Eastern Europe, 317 Sausages of the Nordic countries, 318 References, 320 37 Asian Products, 321 Ming-Ju Chen, Rung-Jen Tu, and Sheng-Yao Wang

37.1 37.2 37.3 37.4

Introduction, 321 Chinese products, 321 South East Asian products, 324 Himalayan fermented meat products, 326 References, 326

Part VIII Fermented Products from Poultry and Other Meats, 329 38 Fermented Poultry Sausages, 331 E. Arnaud, S.J. Santchurn, and A. Collignan

38.1 Introduction, 331 38.2 Fermented poultry sausages, 332 38.3 Other fermented products, 336 References, 336 39 Fermented Sausages from Other Meats, 339 Emin Burçin Özvural and Halil Vural

39.1 Introduction, 339 39.2 Fermented products from other meats, 339 39.3 Scientific studies on other meats, 340 References, 342

Part IX Ripened Meat Products, 345 40 US Products-Dry-Cured Hams, 347 Dana J. Hanson, Gregg Rentfrow, M. Wes Schilling, W. Benjy Mikel, Kenneth J. Stalder, and Nicholas L. Berry

40.1 40.2 40.3 40.4 40.5 40.6 40.7

Introduction, 347 Country ham standards, 347 Commercial dry-cured ham production in the United States, 348 Ham curing at home, 351 Safety, 352 Cooking, 352 Research, 352 References, 353 41 Central and South American Products, 355 Silvina Fadda and Graciela Vignolo

41.1 41.2 41.3 41.4 41.5

Introduction, 355 Meat consumption and habits, 355 Meat production in Latin American countries, 355 Typical meat products, microbial ecology, and safety risks, 356 Conclusion, 359 References, 359 42 Mediterranean Products, 361 Mario Estévez, Sonia Ventanas, David Morcuende, and Jesús Ventanas

42.1 Introduction, 361

Contents

42.2 42.3 42.4 42.5

Production of dry-cured hams, 361 Spanish dry-cured hams, 362 Italian dry-cured hams, 365 French dry-cured hams, 367 References, 368 43 Nordic Products, 371 Torunn Thauland Håseth, Gudjon Thorkelsson, Eero Puolanne, and Maan Singh Sidhu

43.1 43.2 43.3 43.4 43.5 43.6 43.7 43.8 43.9

Introduction, 371 Norwegian fenalår, 371 Norwegian pinnekjøtt, 372 Norwegian dry-cured ham (spekeskinke), 373 Icelandic hangikjöt, 373 Faroese skerpikjøt, 373 Greenlandic mattaq and igunaq, 374 Finnish Lapin Poron kylmäsavuliha, 374 Finnish Lapin Poron kuivaliha, 375 References, 375 44 Asian Products, 377 Guang-Hong Zhou and Gai-Ming Zhao

44.1 44.2 44.3 44.4

Introduction, 377 History and traits of Jinhua ham, 377 Processing of Jinhua ham, 377 Possible factors causing differences in Chinese dry-cured hams, 380 References, 381

Part X Biological and Chemical Safety of Fermented Meat Products, 383 45 Spoilage Microorganisms: Risks and Control, 385 Marie-Christine Champomier-Vergès and Monique Zagorec

45.1 45.2 45.3 45.4 45.5

Introduction, 385 Putative spoilage microorganisms, 385 Examples of spoilage occurring in fermented sausage, 386 Strategies for spoilage control, 386 Conclusion, 387 References, 388 46 Pathogens: Risks and Control, 389 Panagiotis Skandamis and George-John E. Nychas

46.1 46.2 46.3 46.4 46.5

Introduction, 389 Hazard identification, 390 Hazard characterization: defense mechanism, 390 Exposure assessment, 392 Control measures, 406 References, 409 47 Biogenic Amines: Risks and Control, 413 M. Carmen Vidal-Carou, M. Teresa Veciana-Nogués, M. Luz Latorre-Moratalla, and Sara Bover-Cid

47.1 47.2 47.3 47.4

Introduction: biogenic amine classification and relevance, 413 Health risks of biogenic amines in fermented sausages, 413 Aminogenesis in fermented sausages and measures for its control, 415 Conclusion, 424 References, 424

xiii

xiv

Contents

48 Toxic Compounds of Chemical Origin, 429 Milagro Reig and Fidel Toldrá

48.1 48.2 48.3 48.4 48.5 48.6

Introduction, 429 N-nitrosamines, 429 Polycyclic aromatic hydrocarbons (PAHs), 430 Oxidation, 431 Veterinary drug residues, 431 Environmental contaminants, 433 References, 433 49 Foodborne Outbreaks, 435 Colin Pierre

49.1 49.2 49.3 49.4 49.5 49.6 49.7 49.8 49.9

Part XI

Introduction, 435 Staphylococcus aureus, 435 Salmonella spp., 435 Verotoxigenic strains of Escherichia coli, 436 Yersinia enterocolitica, 437 Listeria monocytogenes, 437 Thermotolerant Campylobacter, 438 Parasites, 438 Conclusion, 438 References, 438

Processing Sanitation and Quality Assurance, 441

50 Basic Sanitation, 443 Beatriz Melero, Ana M. Diez, and Jordi Rovira

50.1 50.2 50.3 50.4

Introduction, 443 Raw materials and ingredients, 443 Plant environment, 443 Personnel hygiene and training, 446 References, 448 51 Processing Plant Sanitation, 451 Jordi Rovira, Ana M. Diez, and Beatriz Melero

51.1 51.2 51.3 51.4 51.5

Introduction, 451 Fermented meat products and poultry, 451 Fermented sausage processing plant sanitation, 452 Methods of evaluating the sanitation state of a plant, 457 Final considerations, 458 References, 458 52 Quality Control, 461 Fidel Toldrá, Mónica Flores, and M. Concepción Aristoy

52.1 52.2 52.3 52.4

Introduction, 461 Quality controls at each stage of processing, 461 Control of drying, 462 Control of sensory quality, 462 References, 466 53 HACCP: Hazard Analysis and Critical Control Points, 469 M.J. Fraqueza and A.S. Barreto

53.1 The HACCP concept: why use it, 469

Contents

53.2 HACCP model for fermented sausages: a generic model for HACCP implementation in traditional establishments and small fermented sausage plants, 470 53.3 Validation of the operative HACCP plan, 483 53.4 Revision of the HACCP plan, 483 53.5 Certification of food safety management systems, 484 References, 484 54 Quality Assurance Plan, 487 Friedrich-Karl Lücke

54.1 54.2 54.3 54.4 54.5 54.6 54.7

Introduction, 487 General remarks on the purchase and selection of raw materials, 487 Quality assurance plans and records for fermented sausages, 488 Quality assurance plans and records for raw dry hams, 490 Slicing, packaging, and storage of fermented sausages and raw dry hams, 492 End-product testing, 492 General remarks about the structure and extent of documentation, 493 References, 493

Index, 495

xv

List of Contributors

Dong Uk Ahn Department of Animal Science Department, Iowa State University, Ames, IA, USA

Shai Barbut Food Science Department, University of Guelph, Guelph, ON, Canada

Valentina Alessandria Università di Torino, Dipartimento di Scienze Agrarie, Forestali e Alimentari, Turin, Italy

A.S. Barreto Faculdade de Medicina Veterinária CIISA, Universidade de Lisboa, Lisbon, Portugal

J. Anba-Mondoloni INRA, UMR1319 Micalis, Jouy-en-Josas, France; AgroPArisTech, UMR Micalis, Jouy-en-Josas, France

Lopa Basu Ohio State University, Columbus, OH, USA

Ana Andres Institute of Food Engineering for Development, Food Science and Technology Department, Universitat Politècnica de València, Valencia, Spain Diana Ansorena Department of Food Science, Nutrition and Physiology, University of Navarra, Pamplona, Spain Keizo Arihara School of Veterinary Medicine, Kitasato University, Towada-shi, Aomori, Japan M. Concepción Aristoy Instituto de Agroquímica y Tecnología de Alimentos (CSIC), Paterna, Valencia, Spain E. Arnaud UMR QUALISUD, CIRAD, France Iciar Astiasarán Department of Food Science, Nutrition and Physiology, University of Navarra, Pamplona, Spain Lars Axelsson Nofima, Ås, Norway Teresa Aymerich Institute for Food and Agricultural Research and Technology (IRTA), Food Safety Program, Monells, Spain José M. Barat Food Science and Technology Department, Universitat Politècnica de València, Valencia, Spain

Elettra Berni Department of Microbiology, SSICA, Parma, Italy Nicholas L Berry Department of Animal Science, Iowa State University, Ames, IA, USA Sara Bover-Cid IRTA Food Safety Programme, Institute for Food and Agricultural Research and Technology, Finca Camps i Armet, Monells, Spain Elizabeth Boyle Department of Animal Sciences and Industry, Kansas State University, Manhattan, KS, USA Patricia Castellano Centro de Referencia para Lactobacilos (CERELA), CONICET, Tucumán, Argentina Marie-Christine Champomier-Vergès INRA, UMR1319 Micalis, Jouy-en-Josas, France; AgroPArisTech, UMR Micalis, Jouy-en-Josas, France Ming-Ju Chen Department of Animal Science and Technology, National Taiwan University, Taipei, Taiwan, Republic of China Suey Ping Chi Department of Animal Products Processing, Livestock Research Institute, Council of Agriculture, Hsinhua, Taiwan, Republic of China Souad Christieans ADIV, Clermont-Ferrand Cedex, France xvii

xviii

List of Contributors

Pier Sandro Cocconcelli Istituto di Microbiologia, Centro Ricerche Biotecnologiche, Università Cattolica del Sacro Cuore, Piacenza-Cremona, Italy

Cecilia Fontana Istituto di Microbiologia, Centro Ricerche Biotecnologiche, Università Cattolica del Sacro Cuore, Piacenza-Cremona, Italy

Luca Cocolin Università di Torino, Dipartimento di Scienze Agrarie, Forestali e Alimentari, Turin, Italy

M.J. Fraqueza Faculdade de Medicina Veterinária CIISA, Universidade de Lisboa, Lisbon, Portugal

A. Collignan UMR QUALISUD, Institut des Régions Chaudes, Montpellier, France

Reinhard Fries Panel Veterinary Public Health, Institute of Meat Hygiene and Technology, Faculty of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany

Lorenzo de la Hoz Departamento de Nutrición, Bromatología y Tecnología de los Alimentos, Facultad de Veterinaria, Universidad Complutense de Madrid, Madrid, Spain

M.L. García Departamento Nutrición, Bromatología y Tecnología de los Alimentos, Facultad Veterinaria, Universidad Complutense, Madrid

Daniel Demeyer Laboratory of Animal Production and Animal Product Quality, Department of Animal Production, Ghent University, Melle, Belgium

Margarita Garriga Institute for Food and Agricultural Research and Technology (IRTA), Food Safety Program, Monells, Spain

L. De Vuyst Vrije Universiteit Brussel, Research Group of Industrial Microbiology and Food Biotechnology (IMDO), Brussels, Belgium

T. Goudman Vrije Universiteit Brussel, Research Group of Industrial Microbiology and Food Biotechnology (IMDO), Brussels, Belgium

Ana M. Diez Department of Biotechnology and Food Science, University of Burgos, Burgos, Spain

Raúl Grau Food Science and Technology Department, Universitat Politècnica de València, Valencia, Spain

Paola Dolci Università di Torino, Dipartimento di Scienze Agrarie, Forestali e Alimentari, Turin, Italy

Dana J Hanson Food, Bioprocessing & Nutrition Sciences, North Carolina State University, Raleigh, NC, USA

E. Dordet-Frisoni INRA, UR454 Microbiologie, Saint-Genès Champanelle, France

Torunn Thauland Håseth Animalia—the Norwegian Meat Research Centre, Oslo, Norway

Mario Estévez Department of Food Technology, University of Extremadura, Extremadura, Spain Silvina Fadda Centro de Referencia para Lactobacilos (CERELA), CONICET, Tucumán, Argentina Chris Fedler Department of Food Science and Human Nutrition, Iowa State University, Ames, IA, USA Manuela Fernández Departamento de Nutrición, Bromatología y Tecnología de los Alimentos, Facultad de Veterinaria, Universidad Complutense de Madrid, Madrid, Spain Mónica Flores Instituto de Agroquímica y Tecnología de Alimentos (CSIC), Paterna, Valencia, Spain

Even Heir Nofima, Ås, Norway Eva Hierro Departamento de Nutrición, Bromatología y Tecnología de los Alimentos, Facultad de Veterinaria, Universidad Complutense de Madrid, Madrid, Spain Askild Holck Nofima, Ås, Norway Karl O. Honikel Max Rubner-Institute, Federal Research Centre for Nutrition and Food, Kulmbach, Germany Y.H. Hui Science Technology System, West Sacramento, CA, USA Melvin C. Hunt Department of Animal Sciences and Industry, Kansas State University, Manhattan, KS, USA

List of Contributors

xix

Tom C. Johannessen Nofima, Ås, Norway

Herbert W. Ockerman Ohio State University, Columbus, OH, USA

Sisse Jongberg Food Chemistry, Department of Food Science, University of Copenhagen, Frederiksberg, Denmark

Alicia Olivares Instituto de Agroquímica y Tecnología de Alimentos (CSIC), Paterna, Valencia, Spain

M. Luz Latorre-Moratalla Departament de Nutrició i Bromatologia, Campus de l’Alimentació de Torribera, Universitat de Barcelona-INSA-Xarta, Santa Coloma de Gramenet, Spain

Juan A. Ordóñez Departamento de Nutrición, Bromatología y Tecnología de los Alimentos, Facultad de Veterinaria, Universidad Complutense de Madrid, Madrid, Spain

Isabelle Lebert INRA, UR454 Microbiologie, Saint-Genès Champanelle, France

Emin Burçin Özvural Department of Food Engineering, Faculty of Engineering, Çankırı Karatekin University, Çankırı, Turkey

F. Leroy Vrije Universiteit Brussel, Research Group of Industrial Microbiology and Food Biotechnology (IMDO), Brussels, Belgium Sabine Leroy INRA, UR454 Microbiologie, Saint-Genès Champanelle, France Friedrich-Karl Lücke Hochschule Fulda (University of Applied Sciences), Fulda, Germany Robert Maddock Department of Animal & Range Sciences, North Dakota State University, Fargo, ND, USA

Ronald B. Pegg Department of Food Science & Technology, University of Georgia, Athens, GA, USA Trinidad Pérez-Palacios School of Veterinary Science, University of Extremadura, Caceres, Spain Esko Petäjä-Kanninen Department of Food Technology, University of Helsinki, Helsinki, Finland Colin Pierre French Food Safety Agency, Technopôle Brest-Iroise, Plouzané, France

Beatriz Melero Department of Biotechnology and Food Science, University of Burgos, Burgos, Spain

S. Planchon CTCPA, Site Agroparc, Avignon, France

W. Benjy Mikel Department of Food Science, Nutrition, and Health Promotion, Mississippi State University, Mississippi State, MS, USA

Ken Prusa Department of Food Science and Human Nutrition, Iowa State University, Ames, IA, USA

Byungrok Min Food Science and Technology Program, Department of Agriculture, Food, and Resource Sciences, University of Maryland Eastern Shore, Princess Anne, MD, USA

Eero Puolanne Department of Food Technology, University of Helsinki, Helsinki, Finland

Jens K.S. Møller Chr. Hansen A/S, Natural Colors Division, Hoersholm, Denmark David Morcuende Department of Food Technology, University of Extremadura, Extremadura, Spain Asgeir Nilsen Matforsk A/S, Ås, Norway George-John E. Nychas Laboratory of Microbiology and Biotechnology of Foods, Department of Food Science & Human Nutrition, Agricultural University of Athens, Athens, Greece

Kalliopi Rantsiou Università di Torino, Dipartimento di Scienze Agrarie, Forestali e Alimentari, Turin, Italy Milagro Reig Instituto de Ingeniería de Alimentos para el Desarrollo, Universitat Politècnica de València, Ciudad Politécnica de la Innovación, Valencia, Spain Gregg Rentfrow Department of Animal and Food Science, University of Kentucky, Lexington, KY, USA Marit Rødbotten Matforsk A/S, Ås, Norway

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List of Contributors

Pedro Roncalés Department of Animal Production and Food Science, Laboratory of Food Technology, Faculty of Veterinary Sciences, University of Zaragoza, Zaragoza, Spain Jordi Rovira Department of Biotechnology and Food Science, University of Burgos, Burgos, Spain Jorge Ruiz Department of Food Science, University of Copenhagen, Copenhagen, Denmark Robert E. Rust Iowa State University, Ames, IA, USA S.J. Santchurn Department of Agricultural and Food Science, University of Mauritius, Faculty of Agriculture, Réduit, Mauritius M. Wes Schilling Department of Animal and Food Science, University of Kentucky, Lexington, KY, USA M.D. Selgas Departamento Nutrición, Bromatología y Tecnología de los Alimentos, Facultad Veterinaria, Universidad Complutense, Madrid Maan Singh Sidhu The Research Council of Norway, Oslo, Norway Zdzisław E. Sikorski Department of Food Chemistry, Technology, and Biotechnology, Gda´nsk University of Technology, Gda´nsk, Poland Izabela Sinkiewicz Department of Food Chemistry, Technology, and Biotechnology, Gda´nsk University of Technology, Gda´nsk, Poland Panagiotis Skandamis Laboratory of Food Quality Control and Hygiene, Department of Food Science & Human Nutrition, Agricultural University of Athens, Athens, Greece Leif H. Skibsted Food Chemistry, Department of Food Science, University of Copenhagen, Frederiksberg, Denmark Kenneth J Stalder Department of Animal Science, Iowa State University, Ames, IA, USA Régine Talon INRA, UR454 Microbiologie, Saint-Genès Champanelle, France Gudjon Thorkelsson University of Iceland, Reykjavik, Iceland

Fidel Toldrá Instituto de Agroquímica y Tecnología de Alimentos (CSIC), Paterna, Valencia, Spain Rung-Jen Tu Livestock Research Institute, Council of Agriculture, Executive Yuan, Tainan, Taiwan, Republic of China M. Teresa Veciana-Nogués Departament de Nutrició i Bromatologia, Campus de l’Alimentació de Torribera, Universitat de Barcelona-INSA-Xarta, Santa Coloma de Gramenet, Spain Jesús Ventanas Department of Food Technology, University of Extremadura, Extremadura, Spain Sonia Ventanas Department of Food Technology, University of Extremadura, Extremadura, Spain M. Carmen Vidal-Carou Departament de Nutrició i Bromatologia, Campus de l’Alimentació de Torribera, Universitat de Barcelona-INSA-Xarta, Santa Coloma de Gramenet, Spain Graciela Vignolo Centro de Referencia para Lactobacilos (CERELA), CONICET, Tucumán, Argentina Halil Vural Department of Food Engineering, Faculty of Engineering, Hacettepe University, Ankara, Turkey Sheng-Yao Wang Department of Animal Science and Technology, National Taiwan University, Taipei, Taiwan, Republic of China; Experimental Farm, National Taiwan University, Taipei, Taiwan, Republic of China Yun Chu Wu Department of Animal Science and Biotechnology, Tunghai University, Taiwan, Republic of China Monique Zagorec INRA, UMR 1014 Secalim, France; LUNAM Université, Oniris, Nantes, France Gai-Ming Zhao College of Food Science and Technology, Henan Agricultural University, Zhengzhou, Republic of China Guang-Hong Zhou Key Laboratory of Meat Processing and Quality Control, MOA, College of Food Science and Technology, Nanjing Agricultural University, Nanjing, Republic of China

Preface

Fermented meat products have been consumed for centuries in many different parts of the world and constitute one of the most important types of food. Based on the natural meat microbiota, a wide range of products have been prepared since ancient times; different products are created by varying the mixture of meats and salt and through the addition of spices and seasonings, giving rise to a great variety of flavors and textures. Fermented meat products are today receiving increased interest from consumers all over the world, who are seeking new gustatory experiences. Most of these products still rely primarily on local, traditional manufacturing processes, since little scientific information is available on their creation, but scientific knowledge has become an important tool for consistent production of high-quality and safe products. The first edition of this book dates from 2007 and contains topics spread across 50 chapters. New developments have evolved very rapidly in recent years and this new second edition contains 54 chapters: both updated and revised versions of the old ones and new chapters on low-sodium meats, probiotics, and methodologies for the study of microbial ecology, as well as expanded detail on drying and smoking techniques. These are grouped into 11 parts. Part I deals with general aspects such as curing, fermentation, drying, and smoking. Part II describes the main characteristics and uses of raw materials and ingredients. Part III is focused on the microbiology involved in meat fermentation and describes the most commonly applied starter cultures and methodologies for the study of microbial ecology. Part IV looks into the sensory properties of fermented meat products, while Part V examines their composition and nutritional quality, as well as low-sodium meat products, packaging, and international standards. Parts VI and VII cover the manufacture and characteristics of semidry-fermented and dry-fermented sausages, respectively. Fermented poultry sausages and other fermented meats are described in Part VIII, while Part IX looks at the manufacture and characteristics of ripened meat products, especially dry-cured hams. Part X covers biological and

chemical safety aspects, and, finally, Part XI is focused on sanitation and quality assurance. This Handbook provides an updated and comprehensive overview of meat fermentation. It includes important developments that have occurred in the last few decades, including the role of microorganisms naturally present in meat or added as starter cultures, important modern safety aspects, information regarding nutritional quality and sensory attributes, and the primary chemical, biochemical, physical, and microbiological changes that occur during processing and a summary of how they influence the final product quality. It also provides a detailed description of the major fermented meat products found around the world and the processing technologies currently applied in meat processing plants. This book is the result of the expertise of more than 90 international contributors from 18 different countries. These experts from industry, government, and academia have been led by an editorial team of 5 members from 4 different countries. The editorial team wishes to thank all the contributors for making this book possible and remember those who sadly passed away either before or during the preparation of this book: Esko Petäjä-Kanninen, Lorenzo de la Hoz, and especially Karl O Honikel, a very good friend and excellent meat scientist. We also thank the production team at Wiley Blackwell, giving special recognition to David McDade, Senior Commissioning Editor and the coordinator of the project, and Fiona Seymour, Senior Project Editor. We sincerely hope that you will find this book enlightening and that it provides you with a better understanding of fermented meat and poultry products. Fidel Toldrá Y.H. Hui Iciar Astiasarán Joseph G. Sebranek R Talon

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PART I

Meat Fermentation Worldwide: Overview, Production, and Principles

1

Dry-Fermented Sausages and Ripened Meats: An Overview Fidel Toldrá1 and Y.H. Hui2 1

Instituto de Agroquímica y Tecnología de Alimentos (CSIC), Paterna, Valencia, Spain 2 Science Technology System, West Sacramento, CA, USA

1.1 Introduction Drying and smoking were probably the first food-preservation techniques to be developed, in ancient Greece and Rome (Zeuthen, 2007). In fact, the names “sausage” and “salami” probably originate from the Latin words “salsiccia” and “salumen,” respectively (Toldrá, 2012). Historically, the manufacturing procedures used to make fermented sausages were adapted to the climatic conditions of the production area. For instance, Mediterranean meat products are dried to low water activity (aw ) values, taking advantage of the long dry and sunny days, while in Northern Europe fermented sausages require smoking for further preservation (Toldrá, 2006, 2014a). Summer sausage is traditionally produced in the summer and is heated for safety reasons (Zeuthen, 1995). Preservation results from a series of specific factors known as “hurdle effects” (Leistner, 1992): • addition of nitrite, salt, and/or sugar; • reduction of redox potential; • introduction of lactic acid bacteria (LAB); • lowering of pH; • decreasing of aw ; • smoking. The sausage remains stable throughout this sequence of hurdles (Leistner, 1995). LAB play important roles in safety, nutrition, and sensory quality (Toldrá et al., 2001), and develop important reactions essential to the development of adequate color, texture, and flavor (Demeyer & Toldrá, 2004). Details can be found in Parts II and III of this book. This chapter lists some of the most important fermented sausages produced worldwide. Further details of sausages and ripened meat products from North America, the Mediterranean, and Northern Europe and Asia can be found in Parts VI, VII, VIII, and IX. Space limitation prohibits an in-depth discussion of fermented sausages from other parts of the world; the interested reader can refer to the references for further information.

1.2 Fermented sausages and ripened meats around the world 1.2.1 North America Manufacturing practices were brought to North America by the first European settlers. Today, many European fermented sausages can be found in northern states such as Wisconsin (Toldrá & Reig, 2007). Lebanon bologna is a semidry-fermented sausage originating from Lebanon County, Pennsylvania. It is produced from beef and black pepper, fermented to a very high pH, and heavily smoked (Rust, 2004). Pepperoni is produced from pork and/or beef and seasoned with red pepper, ground cayenne pepper, pimento, aniseed, and garlic. It has a small diameter and is smoked.

1.2.2 South and Central America There is a general Spanish and Italian influence on fermented meat products in many Latin America countries. Italian milano and cacciaturi are consumed in Uruguay, Brazil, and Mexico, among other places. In the Andes, traditional fermented sausages are made from llama meat and guanaco.

1.2.3 The Mediterranean Many types of dry-fermented sausage are produced in the Mediterranean area. They are usually dried, due to the climate, and are rarely smoked. They have a variety of diameters, shapes, sizes, spices, seasonings, and sensory characteristics. Their names differ according to the geographic origin, sometimes even between very close areas (Toldrá, 2006). Pork is the main meat, and fungi starters may be used for development on the external surface (Talon et al., 2004). Salamis of medium diameter (around 6 cm) include French menage, French saucisson d’Alsace, Italian turista, and Spanish salchichón, while those of larger diameter include French varzi, Italian milano, and Italian crespone; the latter may be ripened for more than 60 days (Toldrá & Flores, 2014). Coppa is an Italian salami with cylindrical shape. It is made from pork shoulder butt salted for 7–10 days

Handbook of Fermented Meat and Poultry, Second Edition. Edited by Fidel Toldrá. © 2015 John Wiley & Sons, Ltd. Published 2015 by John Wiley & Sons, Ltd.

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Handbook of Fermented Meat and Poultry

and dried for 2–4 weeks. Spanish chorizo, which has a strong red color, is seasoned with garlic, pepper, and oregano (Toldrá, 2002). Mortadella bologna is produced from pork meat and fat, and the final sausage is thermally treated to an internal temperature of 68 ∘ C (Toldrá, 2014a). Dry-cured ham is extensively consumed in Mediterranean countries. It is a dry-cured whole-meat product produced by curing, salting, drying, and ripening for as long as 24, or sometimes even 36, months (Toldrá, 2014b). It receives different names according to the region, such as serrano or ibérico in Spain, prosciutto di Parma or San Danielle in Italy, Bayonne in France, and Ardennes in Belgium (Toldrá, 2014a).

& Abd-Allach, 2004). Soudjouk sausages, using only beef, buffalo, and/or mutton and fat-tailed sheep, are produced in Turkey (Gökalp & Ockerman, 1985). They may be heavily seasoned by garlic, red and black pepper, cumin, pimento, and olive oil. Pastırma is extensively consumed in Turkey and North African countries. It is a dry-cured whole-meat product produced by curing, pressing, and drying. Up to 21 different types can be found, depending on what part of the animal (usually water buffalo or beef) is used (Yalinkiliç et al., 2014). It is usually covered with a layer prepared from water, garlic, red pepper, paprika, and flour from the seed of Trigonella foenum-graecum (Ceylan & Aksu, 2011). Pastırma production typically occurs in October/November, a period called “pastırma yazı” (“summer of pastırma”).

1.2.4 Northern Europe A good number of fermented meats are produced in Northern Europe. The greuβner salami is produced in Thuringia, Germany. It is a sliceable sausage produced from beef and some pork, as well as fat, and flavored with garlic, pepper, and other spices. It undergoes a long-term fermentation process and cold smoking. The rügenwalder teewurst is a semidry-fermented sausage, also produced from beef and pork, which is fermented and cold-smoked (Gibis & Fischer, 2004). The Austrian katwurst is a long, dried sausage. The Swedish metwursk contains some potato, in addition to spices and seasonings. Other meats can be added to the formulation of sausages in Scandinavian countries, such as horse meat in farepolse, toppen, trondermorr, stabbur, and sognekorr in Norway and kotimainen meetwurst in Finland; lamb meat in lambaspaeipylsa in Iceland; and reindeer meat in poro meetwurst in Finland and rallersnabb gilde in Norway (Campbell-Platt, 1995). Several fermented sausages are produced in Poland, mainly from pork, but also beef, game, and poultry (Pisula, 2004). Krakowscha sucha is produced from pork and beef, plus black pepper, nutmeg, and garlic. It is dry-cured, smoked, cooked, and dried for about 3 weeks. Kabanosy is produced from pork and black pepper, nutmeg, and caraway. It is smoked and dried for 3–5 days. Jalowcowa is produced from pork and a little beef, plus pepper and juniper. It is dry-cured, smoked, cooked, and dried for 3–5 days (Pisula, 2004).

1.2.5 Eastern Europe The Hungarian salami is a good example of a typical salami. It is intensively smoked and then its surface is inoculated with mold starters or spontaneous mold growth (Incze, 2004). It is seasoned with white pepper, garlic, red wine, and paprika. Similar sausages include winter salami, also produced in Hungary, and hermannstädler, produced in Romania (Roca & Incze, 1990). Russian salami and Moscow salami are produced in Russia from pork, and sometimes some beef.

1.2.6 The Middle East Fermented sausages are produced from many different animals (beef, buffalo, mutton, lamb, goat, camel, and horse) in Middle Eastern countries. Pork meat is not used, because of religious prohibition. Sausages, which can contain rice, wheat, corn, and rice flour, are cured and smoked. Different flavors are imparted by the addition of olive oil, garlic, cinnamon, onion, paprika, black pepper, rosemary, and so on. Fermented and strongly smoked beef sausages were first produced in Lebanon and then spread to other countries (El-Magoli

1.2.7 Africa Biltong is a typical South African meat product. It is produced from young and lean carcasses of either cattle or game, especially from the round, loin, and tenderloin. The meat is ripened and dried until losses exceed 50%. Salt, sugar, pepper, and roasted ground are added. Vinegar and saltpeter can also be used (Strydom, 2004). Other typical fermented and sun-dried products are summarized by Campbell-Platt (1995). Most are produced in north-eastern Africa. Miriss and mussran are made from the fat surrounding a lamb’s stomach and small intestine, respectively. Similar products include twini-digla and um-tibay. Beirta is made in Sudan from goat meat and offal, kaidu-digla is made from chopped bones, and dodery, mulaa el-sebit, and aki-el-muluk are made from crushed bones, marrow, and fat.

1.2.8 East Asia Most of the information in this chapter on fermented sausages from East Asian countries is derived from recipe books in both Chinese and English. The English references include: Aidells & Bruce (2000), Campbell-Platt (1995), Inglis et al. (1998), Leistner (1995), Rogers (2003), Solomon (2002), and Trang (2006). Although their descriptions here do not detail the fermentation stage, most East Asian sausages require short or long-term fermentation during the manufacturing processes. India, Indonesia, Japan, Malaysia, and various other countries do not have specialty fermented sausages, although ethnic groups within these countries have their own ethnic heritage sausages, such as the Chinese, the Thais, and so on. European-style sausages are now produced in Japan and India. 1.2.8.1 Chinese sausages “Lap cheong” (la chang) is a general term for Chinese sausages, but it can also be used to describe Chinese pork sausages. Literally, it means winter (lap) intestines (cheong), which can be interpreted as “intestines stuffed in the winter.” Traditionally lap cheong is made in the winter months to take advantage of the lower temperatures, which reduce the chance of spoilage during curing after the sausages are stuffed. The ingredients vary from place to place, but essentially they are cut-up pork and pork fat (today ground pork and fat), sugar, and salt, plus optional ingredients such as soy sauce, alcoholic beverages, spices, and others. The amount of pork fat used also varies, with regular and low-fat types of lap cheong more common nowadays. Traditionally, when the intestines or casings are stuffed

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Dry-Fermented Sausages and Ripened Meats: An Overview

at the beginning of the winter season, they are hung by a string in a ventilated area to gradually dry the ingredients and the surface, and to produce the typical flavor (odor, color, and texture). With the decrease in aw and moisture content, the product hardens and can be kept edible (after cooking) for the winter and spring months. It is not uncommon to see mold and yeast development on the surface of the dried product when the relative humidity is high. In order to extend the self-life, some people store a small amount of the dried product in oil in a sealed container in a cool place. This can keep the product available for the summer and even the autumn months. For several decades, industrial production of lap cheong has involved curing or drying of the green sausage in temperature- and humidity-controlled dryers, in order to speed up the process. The product is now packed in vacuum-sealed pouches and it is recommended these be stored in refrigerators in order to maintain quality year-round. However, the traditional procedure is still practiced in rural areas of China.

Aap gon cheong Aap (duck) gon (liver) cheong (sausage) is a specialty Cantonese product made in a similar manner to lap cheong, but with cut-up duck liver replacing the pork. The amount produced is small due to the low availability of duck liver. Traditionally, soy sauce is one of the main ingredients in the making of duck-liver sausage, and it contributes to the special flavor. Gam ngan cheong Gam (gold) ngan (silver) cheong (sausage) is a very special Cantonese product that is made without a casing. A chunk of pork fat is cut into a wedge shape and wrapped with thin slices of pork liver that have been marinated with salt and sugar. The gam ngan cheong is then dried naturally in the same way lap cheong is cured. Because of concerns over cholesterol and fat intakes, this product has become less popular recently. Chicken-liver sausage, with or without pig liver This is a modification of aap gon cheong, with chicken and/or pig liver replacing the duck liver. 1.2.8.2 Singaporean sausages Singaporean sausages are similar to Chinese sausages. This is understandable as the majority of the population in Singapore is of Chinese ethnic origin. They include special-grade (reduced-fat) pork sausage, chicken sausage, and pig-liver sausage. 1.2.8.3 Thai sausages Sai ua (a dried northern Thai sausage) Sai ua is made by stuffing pork with Thai curry paste (onion, galangal, lemon grass, parsley’s root, curcuma, chili, and salt mashed in shrimp paste) into a pork casing. It is dried and roasted before consumption.

North-eastern sour Thai-style sausage North-eastern sour Thai sausage is made with ground pork, cooked rice, nitrite, erythorbate, pepper, salt, and sugar. After the mixture is stuffed into a pork casing, it is kept at room temperature for about 24 hours to allow lactic acid fermentation. The sour sausage requires thorough cooking (such as roasting or frying) before consumption.

5

Nham (Thai fermented sausage) Nham is made similarly to north-eastern Thai sour sausage, except that chili and pork skin are also added, and the mixture is packed in bamboo leaf or plastic film. After keeping (fermenting) for 3–4 days at room temperature, the sausage is ready for cooking and consumption. Currently, some manufacturers apply irradiation treatment to kill parasites and ensure safety. Goon Chiang Goon chiang is made by first marinating the pork with nitrite at refrigerating temperature for 24 hours, and then grinding and mixing it with sugar and erythrobate and stuffing it into pork casing. It is dried at 60 ∘ C to appropriate dryness. This sausage requires cooking before consumption. 1.2.8.4 Filipino sausage Longamisa Longamisa is a sweet–sour sausage made rurally using lean pork, pork fat, white vinegar, soy sauce, and sugar. After stuffing, it can be smoked or cooked fresh. 1.2.8.5 Korean sausages Sundae This Korean stuffed sausage is popularly sold by street vendors. It is made with pig’s blood, rice, green onions, garlic, minced pork, and sweet-potato vermicelli, all stuffed into small and large pig’s intestines. It is steamed before consumption.

Soonday Soonday is also popularly sold at public markets. The stuffing consists of firmly cooked rice, crushed garlic and cloves, crushed fresh ginger, black or white pepper, Korean sesame oil, crushed sesame seeds, crushed scallions, and either beef or pork blood. The mixture is stuffed into small beef intestines. The sausages are cooked in water before consumption. 1.2.8.6 Nepalese sausages Nepalese sausage is similar to German sausage except that chicken is used as the main meat ingredient. 1.2.8.7 Sri Lankan sausages Sri Lankan sausage is made with lean pork, pork fat, toasted and ground coriander seeds, ground cinnamon, ground cloves, ground black pepper, finely grated nutmeg, salt, and vinegar. After stuffing, it is cold smoked at temperature not higher than 30 ∘ C for a few hours, to appropriate dryness. It requires proper cooking before consumption.

1.2.9 The Pacific Rim Pepperoni is produced in Australia. Vento salami, made from beef with peppercorns and red wine, is also produced there (Campbell-Platt, 1995).

1.3 The importance of fermented sausages Fermented sausages are very popular with most population groups that consume meat. Science and technology have played

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Handbook of Fermented Meat and Poultry

an important role in improving the quality and storage time of fermented sausages, especially in Europe and Central, South, and North America. However, the development and production processes in countries such as China are still more art than science. Most of us like fermented sausages, and this type of processed meat product has been and will continue to be significant in our diets.

Acknowledgement The authors thank their personal friends and colleagues in East Asia for contributing significant information on sausages associated with their native countries.

References Aidells B, Bruce B. 2000. Aidells’s Complete Sausage Book. Ten Speed Press, Berkeley, CA, USA. Campbell-Platt G. 1995. Fermented meats—a world perspective. In: Fermented Meats. G Campbell-Platt, PE Cook (eds), pp. 39–51. London: Blackie Academic & Professional. Ceylan S, Aksu M˙I. 2011. Free amino acids profile and quantities of “sırt,” “bohca” and “sekerpare” pastirma, dry cured meat products. Journal of the Science of Food and Agriculture, 91, 956–962. Demeyer D, Toldrá F. 2004. Fermentation. In: Encyclopedia of Meat Sciences. W Jensen, C Devine, M Dikemann (eds), pp. 467–474. London: Elsevier Science. El-Magoli SB, Abd-Allach MA. 2004. Ethnic meat products: Middle East. In: Encyclopedia of Meat Sciences. W Jensen, C Devine, M Dikemann (eds), pp. 453–455. London: Elsevier Science. Gibis M, Fischer A. 2004. Ethnic meat products: Germany. In: Encyclopedia of Meat Sciences. W Jensen, C Devine, M Dikemann (eds), pp. 444–451. London: Elsevier Science. Gökalp HY, Ockerman HW. 1985. Turkish-style fermented sausage (soudjouk) manufactured by adding different starter cultures and using different ripening temperatures. Fleischwirtschaft, 65, 1235–1240. Incze K. 2004. Mold-ripened sausages. In: Handbook of Food and Beverage Fermentation Technology. YH Hui, LM Goddik, J Josephsen, PS Stanfield, AS Hansen, WK Nip, F Toldrá (eds), pp. 417–428. New York: Marcel Dekker. Inglis K, Francione G, Invernizzi L. 1998. Tropical Asian Style. North Clarendon, VT: Periplus Editions. Leistner L. 1992. The essentials of producing stable and safe raw fermented sausages. In: New Technologies for Meat and Meat Products. JM Smulders, F Toldrá, J Flores, M Prieto (eds), pp. 1–19. Nijmegen, The Netherlands: Audet. Leistner L. 1995. Stable and safe sausages world-wide. In: Fermented Meats. G Campbell-Platt, PE Cook (eds), pp. 161–175. London: Blackie Academic & Professional. Pisula A. 2004. Ethnic meat products: Poland. In: Encyclopedia of Meat Sciences. W Jensen, C Devine, M Dikemann (eds), pp. 456–458. London: Elsevier Science.

Roca M, Incze K. 1990. Fermented sausages. Food Reviews International, 6, 91–118. Rogers J. 2003. The Essential Asian Cookbook. Berkeley, CA: Thunder Bay Press. Rust RE. 2004. Ethnic meat products: North America. In: Encyclopedia of Meat Sciences. W Jensen, C Devine, M Dikemann (eds), pp. 455–456. London: Elsevier Science. Solomon C. 2002. The Complete Asian Cookbook. North Clarendon, VT: Tuttle Publishing. Strydom PE. 2004. Ethnic meat products: Africa. In: Encyclopedia of Meat Sciences. W Jensen, C Devine, M Dikemann (eds), pp. 440–441. London: Elsevier Science. Talon R, Leroy-Satrin S, Fadda S. 2004. Dry fermented sausages. In: Handbook of Food and Beverage Fermentation Technology. YH Hui, LM Goddik, J Josephsen, PS Stanfield, AS Hansen, WK Nip, F Toldrá (eds), pp. 397–416, New York: Marcel Dekker. Toldrá F. 2002. Dry-Cured Meat Products. Trumbull, CT: Food & Nutrition Press. Toldrá F. 2006. Meat fermentation. In: Handbook of Food Science, Technology and Engineering, Vol. 4. YH Hui, E Castell-Perez, LM Cunha, I Guerrero-Legarreta, HH Liang, YM Lo, DL Marshall, WK Nip, F Shahidi, F Sherkat, RJ Winger, KL Yam (eds), pp. 181-1–181-12. Boca Raton, FL: CRC Press. Toldrá F. 2012. Biochemistry of fermented meat. In: Food Biochemistry and Food Processing, 2 edn. BK Simpson, LML Nollet, F Toldrá, S Benjakul, G Paliyath, YH Hui (eds), pp. 331–343. Ames, IA: Wiley-Blackwell. Toldrá F. 2014a. Ethnic meat products: Mediterranean. In: Encyclopedia of Meat Sciences, 2 edn. W Jensen, C Devine, M Dikemann (eds). London: Elsevier Science. Toldrá F. 2014b. Curing: dry. In: Encyclopedia of Meat Sciences, 2 edn. W Jensen, C Devine, M Dikemann (eds). London: Elsevier Science. Toldrá F, Flores M. 2014. Sausages, types of: dry and semidry. In: Encyclopedia of Meat Sciences, 2 edn. W Jensen, C Devine, M Dikemann (eds). London: Elsevier Science. Toldrá F, Reig M. 2007. Sausages. In: Handbook of Food Product Manufacturing. YH Hui (ed.), pp. 249–262. John Wiley Interscience. Toldrá F, Sanz Y, Flores M. 2001. Meat fermentation technology. In: Meat Science and Applications. YH Hui, WK Nip, RW Rogers, OA Young (eds), pp. 537–561. New York: Marcel Dekker. Trang C. 2006. The Asian Grill: Great Recipes, Bold Flavors. San Francisco, CA: Chronicle Books. Yalinkiliç B, Aristoy MC, Toldrá F. 2014. Proteolysis in pastırma, a dry-cured meat product. Meat Science, submitted. Zeuthen P. 1995. Historical aspects of meat fermentations. In: Fermented Meats. G Campbell-Platt, PE Cook (eds), pp. 53–67. London: Blackie Academic & Professional. Zeuthen, P. 2007. A historical perspective of meat fermentation. In: Handbook of Fermented Meat and Poultry. F Toldrá, YH Hui, I Astiasarán, WK Nip, JG Sebranek, ETF Silveira, LH Stahnke, R Talon (eds), pp. 1–8. Ames, IA: Blackwell Publishing.

2

Production and Consumption of Fermented Meat Products Herbert W. Ockerman and Lopa Basu Ohio State University, Columbus, OH, USA

2.1 Introduction Meat fermentation is a low-energy, biological-acidulation preservation method that results in unique and distinctive meat properties, including flavor and palatability, color, tenderness, microbiological safety, and a host of other desirable attributes. Changes from raw meat to a fermented product are caused by “cultured” or “wild” microorganisms, which lower the pH. Since this is a biological system, it is influenced by many environmental pressures that need to be controlled in order to produce a consistent product. These factors include a fresh, low-contaminated, consistent raw material, a consistent inoculum, strict sanitation, control of time, temperature, and humidity during production, smoke, and appropriate additives. Lactic acid, which accounts for the antimicrobial properties of fermented meats, originates from the natural conversion of glycogen reserves in the carcass tissues and from the sugar added during product fermentation. A desirable fermentation product is the outcome of acidulation caused by lactic acid production and by lowering of the water activity (aw ) caused by the addition of salt (curing) and drying. Both natural and controlled fermentations involve lactic acid bacteria (LAB). Their growth must be understood to produce a safe and marketable product. Most starter cultures today consist of LAB and/or micrococci, selected for their metabolic activity, which often improves flavor development. The reduction of pH and the lowering of water activity are both microbial hurdles that aid in producing a safe product. Fermented sausages often have a long storage life, due to added salt, nitrite, and/or nitrate. They also have a low pH, due to lactic acid production by LAB organisms in the early stages of storage, and to later drying, which reduces the water activity. Production and composition information for fermented products are difficult to obtain, particularly since many of these products are produced and consumed locally and quantities are not recorded. The limited number of references available suggest that the production and consumption are sizeable, however.

2.2 Current products 2.2.1 Definitions A list of characteristics and types of fermented product can be found in Tables 2.1 and 2.2. Guidelines proposed in the United States

(American Meat Institute, 1982; Hui et al., 2004) for the making of fermented dry or semidry sausages include a definition of dry sausage as chopped or ground meat products that, due to bacterial action, reach a pH of 5.3 or less. The drying removes 20–50% of the moisture, resulting in a moisture-to-protein ratio (MP) of no greater than 2.3 : 1.0. Dry salami (US) has an MP of 1.9 : 1.0, pepperoni 1.6 : 1.0, and jerky 0.75 : 1.0. Semidry sausages are similar, except that they have a 15–20% loss of moisture during processing. Semidry sausages also have a softer texture and a different flavor profile than dry sausages. Because of the higher moisture content, semidry sausages are more susceptible to spoilage and are usually fermented to a lower pH, producing a very tangy flavor. Semidry products are generally sold after fermentation (pH 5.3 or less). They are heated, and do not go through a drying process (water activity is usually 0.92 or higher). They are usually smoked during the fermentation cycle (less than 24 hours) and have a maximum pH of 5.3. If the semidry sausage has a pH of 5.0 or less and an MP of 3.1 : 1.0 or less, it is considered to be shelf-stable, but most semidry products require refrigeration (2 ∘ C). In Europe, fermented meat with a pH of 5.2 and a water activity of 0.95 or less is considered shelf-stable (United States Department of Agriculture, 1963). In order to decrease the pH (below 5.0) with limited drying, US semidry products are often fermented rapidly (12 hours or less) at a relatively high temperature (32–46 ∘ C). In Europe, fermentation is slower (24 hours or more) and takes place at a lower temperature, and it results in a higher pH. These differences in speed of fermentation and final pH result in products having different flavors.

2.2.2 Product ingredients 2.2.2.1 Raw meat Beef, mechanically separated beef (up to ∼50%), pork, lamb, chicken, mechanically separated chicken (up to ∼100%), duck, water buffalo, horse, donkey, reindeer, gazelle, porcupine, whale, fish, rabbit, byproducts, and other tissues from a variety of species are used to make fermented meat products. Fermented meat is often divided into two groups: products made from whole pieces of meat, such as hams, and products made from meat chopped into small pieces, such as various types of sausage. Details on producing these products will be provided in later chapters. The predominant bacteria that appear in fresh meat are typically Gram-negative, oxidase-positive, aerobic rods of psychrotrophic

Handbook of Fermented Meat and Poultry, Second Edition. Edited by Fidel Toldrá. © 2015 John Wiley & Sons, Ltd. Published 2015 by John Wiley & Sons, Ltd.

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Handbook of Fermented Meat and Poultry

Table 2.1 Characteristics of different types of fermented sausage. Type of sausage

Characteristics

Dry, long ripening, e.g. dry or hard salami, saucission, pepperoni, shelf stable

Chopped and ground meat Commercial starter culture or back inoculum US fermentation temperature 15–35 ∘ C for 1–5 days Not smoked or lightly smoked US bacterial action reduces pH to 4.7–5.3 (0.5–1.0% lactic acid, total acidity 1.3%, which facilitates drying by denaturing protein, resulting in a firm texture; MP < 2.3 : 1, moisture loss 25–50%; moisture level < 35%) European bacterial action reduces pH to 5.3–5.6 for a more mild taste than US; processing time 12–14 weeks Dried to remove 20–50% of moisture; contains 20–45% moisture, 39% fat, 21% protein, 4.2% salt; aw 0.85–0.86, yield 64% MP no greater than 2.3 : 1.0 Less tangy taste than semidry

Semidry, sliceable, e.g. summer sausage, Holsteiner, cervelat (zervelat), tuhringer, chorizos, refrigerate

Chopped or ground meat Bacterial action reduces pH to 4.7–5.3 (lactic acid 0.5–1.3%, total acidity 1%), processing time 1–4 weeks Dried to remove 8–30% of moisture by heat; contains 30–50% moisture, 24% fat, 21% protein, 3.5% salt; aw 0.92–0.94, yield 90% Usually packaged after fermentation/heating Generally smoked during fermentation No mold MP no greater than 2.3–3.7 : 1.0

Moist; undried; spreadable e.g. teewurst, mettwurst, frishe braunschweiger

Contains 34–60% moisture, production time 3–5 days Weight loss ∼10%, aw 0.95–096 Usually smoked No mold Highly perishable, refrigerate, consume in 1–2 days

Source: Modified from American Meat Institute (1982), Campbell-Platt & Cook (1995), Doyle et al. (1997), Farnworth (2003), Gilliland (1985).

pseudomonads, along with psychrotrophic Enterobacteriaceae, small numbers of LAB, and other Gram-positive bacteria. The lactic and other Gram-positive bacteria become the dominant flora if oxygen is excluded and are encouraged during the fermentation stages. Since the production of fermented meats depends on microorganism growth, it is essential that these products are hygienically processed and chilled prior to use and that they are maintained under refrigeration prior and during the curing operation. 2.2.2.2 Starter cultures Traditionally, fermented products depend on wild inoculum, which usually do not conform to any specific species but are typically related to Lactobacilli plantarum. However, other species, such as Lb. casei and Lb. leichmanii, have been isolated from traditionally fermented meat products (Anon, 1978). In the United States, Lb. plantarum, Pediococcus pentosaceus, and P. acidilactici are the most commonly used starter cultures. In Europe, the most common include Lb. sakei, Lb. plantarum, Pediococcus pentosaceus, Staphylococcus xylosus, S. carnosus, and to a lesser extent Micrococcus spp. Reliance on natural flora results in products with inconsistent quality. The advantage of a starter culture is that the same microorganisms can be used repeatedly, which reduces variation in the finished product, and a larger number of organisms can be added. Today, combined starter cultures are available in which one organism produces lactic acid (e.g. Lactobacilli) and another improves

desirable flavors (Micrococcaceae, Lb. brevis, Lb. buchneri). These combinations can translate into a very good and acceptable product, and almost no undesirable fermented product. However, very little extremely excellent product is produced, since most starter cultures are a combination of just a few species of microorganism and they cannot produce as balanced a flavor as can be obtained when many species are included. Particularly in the Southern European countries, dry sausages are applied with atoxinogenic yeast and fungi to produce products with specific flavor notes. This is done by dipping or spraying. Mold cultures tend to suppress natural molds, and consequently reduce the risk of mycotoxins. Due to the extended ripening and drying of these products, the final pH is usually higher (pH > 5.5), even if it was lower after fermentation, because molds can metabolize lactic acid and produce ammonia. This requires the final water activity to be low enough for preservation. 2.2.2.3 Other ingredients Salt is the major additive in fermented meat products. It is added in levels of 2–4% (2% minimum for desired bind; up to 3% will not retard fermentation), which allow LAB to grow and inhibit several unwanted microorganisms. Nitrite is used at 80–240 mg/kg for antibacterial, color, and antioxidant purposes. Nitrate and nitrite are often used in combination, but nitrate is usually not necessary, except as a reservoir for

2

Production and Consumption of Fermented Meat Products

9

Table 2.2 Types of fermented sausage and areas of production. Type

Area

Production

Sausages

Sensory

Dry fermented, mixed cultures

Southern and Eastern Europe, psychrotrophic lactic acid, optimum growth 10–15 ∘ C

40–60 mm pork, 2–6 mm particle, nitrate, starters, fungi; ferment 10–24 ∘ C, 3 days; ripen 10–18 ∘ C, 3–6 weeks; weight loss > 30%; low water activity; higher pH, 5.2–5.8; lower lactate, 17 mmol/100 g dry matter

Italian salami

Fruity, sweet odor, medium buttery, sour and pungent, more mature

Northern Europe, LAB (Lactobacillus plantarum or Pediococcus) and Micrococcaceae (Staphylococcus carnosus or Micrococcus)

90 mm pork/beef; 1–2 mm particle, nitrite, starters; smoked; ferment 20–32 ∘ C, 2–5 days; rapid acidification to pH < 5; smoking ripen 2–3 weeks; weight loss > 20%; lower pH, 4.8–4.9; higher lactate, 20–21 mmol/100 g dry matter

German salami, 15 mg/g lactate/g

Buttery, sour odor, low levels of spice and fruity notes, more acid

Hungarian salami Nordic salami

More acid More acid

Mold ripened

Europe, United States

Usually with starters Usually with starters, bowl chopper Without starters, bowl chopper Usually with starters, ground Usually with starters Usually with starters

French salami Germany salami Hungarian salami Italian salami California salami Yugoslavian salami

Semidry

United States

Usually with starters

Summer sausage, MP 2.0–3.7 : 1.0 Thuringer Beef sticks

Usually with Pediococcus acidilactici Usually with Pediococcus acidilactici

Beef sticks Pepperoni, MP1.6 : 1.0

Dry

Spanish salchichon, chorizo (usually no starter) French saucisson, 9 mg/g lactate/g

Source: Hui et al. (2004), Demeyer et al. (2000), Schmidt & Berger (1998), Stahnke et al. (1999).

nitrite, which can be useful in long-term processing. Nitrite is also a hurdle, inhibiting bacterial growth and retarding Clostridium and Salmonella multination. Fermentation can be produced with salt alone, but there is a lower microbial risk if nitrite is used as well. Simple sugars such as glucose or dextrose (0.5% total; a minimum of 0.75% is often recommended), can be readily utilized as a fermentation substrate by all LAB. The quantity of sugar influences the rate and extent of acidulation, and also contributes favorably to flavor, texture, and product yield. The amount of dextrose added will directly influence the final product pH, and additional sugar will not decrease pH further since bacterial cultures cannot grow in excess acid. Spices (e.g., black, red, and white pepper, cardamom, mustard, allspice, paprika, nutmeg, ginger, mace, cinnamon, garlic) are often included in the fermented meat formula. Spices are used for flavor and to impart antioxidant properties, and in order to stimulate growth of lactic bacteria. Sodium ascorbate (in the United States also sodium erythorbate) or ascorbic acid (in the United States also erythorbic acid) is used to improve color stability and retard oxidation.

2.2.3 Processing Formulations are numerous even for products with the same name, and some are held in strict security. Examples of formulations and processing procedures can be found in Komarik et al. (1974), Rust (1976), Ockerman (1989), Campbell-Platt & Cook (1995), and Klettner & Baumgartner (1980). Time, temperature, humidity, and smoke all control the quality of the final product. Casing types include natural casings, artificial casings (made from cotton linters), collagen casings, fibrous casings (synthetic, inedible), and cloth bags (for use in the smokehouse or cooker). They are sometimes netted: pre-stuck (pin-pricked) to allow for better smoke penetration and elimination of air pockets. Temperature, time, and relative-humidity combinations are quite variable in industrial production. In general, higher fermentation temperature and greater water activity result in faster lactic acid production. In Europe, fermentation temperatures range from 5 to 26 ∘ C, with lower temperatures used in the Mediterranean area and higher temperatures in Northern Europe. In the United States, semidry products are usually fermented at temperatures that slowly rise to over 35 ∘ C, in order to shorten the fermentation time,

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Handbook of Fermented Meat and Poultry

Table 2.3 Examples of the nutritive composition of fermented meat products. Cervelat

Moisture Calorie (kcal) Protein Fat Monounsaturated Polyunsaturated Saturated Ash Fiber Carbohydrate Sugar Calcium

Soft

Dry

48.4% 307 18.6% 25.5% 13.0 g/100 g 1.2 g/100 g 12.0 g/100 g 6.8% 0 1.6% 0.85% 11 mg/100 g

29.4% 451 24.6% 37.6% — — 6.7% 0 1.7% 14 mg/100 g

which is frequently 12 hours or less. Half-dried summer sausage is fermented for 3 days at 7 ∘ C, 3 days at 27–41 ∘ C, and 2 days at 10 ∘ C, then heated to 58 ∘ C for 4–8 hours, for example. Smoking depends on the tradition and product type in the area of production and can vary to from no smoke to heavy smoke. It is used to contribute flavor and to retard surface bacteria, molds, and yeast. Many semidry sausages are heated after fermentation and/or smoking, which often increases the pH. Often, an internal temperature of 58.3 ∘ C is used. In Europe, drying temperatures of 14 ∘ C, with 78–88% relative humidity, are often used. An air velocity of 1 m/s is employed, resulting in a final water activity of 3.00)b Traditional immersion-cured meat products (number of products) Traditional dry-cured meat products (number of products) Other traditionally cured meat products (number of products)

Maximum residual level (expressed as NaNO2 ) (mg/kg)

150

—

—

50−175

—

50−175

180

50

E 251c

Potassium nitrate

Non-heat-treated meat products

150

—

E 252c

Sodium nitrate

Traditional immersion-cured meat products (number of products) Traditional dry-cured meat products (number of products) Other traditionally cured meat products

300

10−250 (some without NO2 added)

300

> 50 (some without NO2 added) 10−250

250−300

a

When labeled “for food use,” nitrite may be sold only in a mixture with salt or a salt substitute. value of 3.00 is equivalent to 3 minutes’ heating at 121 ∘ C. Nitrates may be present in some heat-treated meat products, resulting from natural conversion of nitrites to nitrates in a low-acid environment. Source: Extract from EU Directive 2006. bF o c

• Sodium nitrite, NaNO2 , sodium salt of nitrous acid, CAS no. 7632-00-0, molecular weight 69 Dalton, white or yellowish white crystals, odorless, density 2.17 g/cm3 , solubility 85.2 g/100 g water at 20 ∘ C and 163 g/100 g water at 100 ∘ C, pH in aqueous solution ∼9, melting point 271 ∘ C, hygroscopic in air, oxidizes in air slowly to nitrate, strong oxidizing agent with organic matter and inorganic material, especially ammonia compounds, toxicity oral rat LD50 85 mg/kg, human LD50 50 mg/kg body weight, irritating to skin and other body surfaces. • Potassium nitrite, KNO2 , potassium salt of nitrous acid, CAS no. 7758-09-0, molecular weight 85.1 Dalton, white or yellowish white crystals, odorless, density 1.92 g/cm3 , solubility ∼300 g/100 g water at 20 ∘ C and 413 g/100 g water at 100 ∘ C, pH in aqueous solution ∼9, melting point 387 ∘ C, instable above 350 ∘ C, strong oxidizing agent with organic matter, toxicity as NaNO2 . • Sodium nitrate (saltpeter), NaNO3 , sodium salt of nitric acid, CAS no. 7631-99-4, used as gun powder, molecular weight 84.99 Dalton, white crystals, odorless, hygroscopic in moist air, density 2.16 g/cm3 , solubility 73 g/100 g water at 0 ∘ C and 180 g/100 g water at 100 ∘ C, pH in aqueous solution ∼7, melting point 307 ∘ C, stable under normal conditions, may oxidize reduced organic matter. • Potassium nitrate (saltpeter), KNO3 , potassium salt of nitric acid, CAS no. 7757-79-1, molecular weight 101.1 Dalton, white crystals,

odorless, salty taste, density 2.11 g/cm3 , solubility 31.6 g/100 g water at 20 ∘ C and 247 g/100 g water at 100 ∘ C, pH in aqueous solution ∼7, melting point 334 ∘ C, stable under normal conditions, may oxidize organic matter and reacts vigorously with ammonia salts. • Nitrous acid, HNO2 , known only in solution, molecular weight 47.02 Dalton, anhydride N2 O3 , which exists only in the solid state at temperatures below −102 ∘ C; above this the liquid is a mixture of N2 O3 ⇆ NO + NO2 , middle strong acid, pKa 3.37. • Nitric acid, HNO3 , CAS no. 7697-37-2, molecular weight 63.01 Dalton, colorless liquid in closed containers, melting point −42 ∘ C, boiling point 86 ∘ C, density 1.52 g/g at 20 ∘ C, mixable in any quantity with water, strong acid, totally dissociates in water. • Nitric oxide/nitrogen oxide, NO, CAS no. 10102-43-9, molecular weight 30 Dalton, colorless gas, melting point −163.6 ∘ C, boiling point −151.8 ∘ C, oxidizes in air 2NO + O2 → N2 O4 → 2 NO2 , can bind to myoglobin to form NOMb, can easily lose an electron to form an NO+ cation, which may react with amines to form Nnitrosamines, formed in the human body and functions as a physiological messenger, playing a role in the cardiovascular, neurologic, and immune systems through pathogen suppression, vasodilation, and neurotransmission (Ignarro, 1990; Lowenstein & Snyder, 1992; Lüscher, 1990, 1992; Marletta, 1989; Moncada et al., 1991; Nathan, 1992; Parthasarathy & Bryan, 2012; Stamler et al., 1992).

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Handbook of Fermented Meat and Poultry

• Nitrogen dioxide, NO2 (or its dimer, N2 O4 ), molecular weight (NO2 ) 46.01 Dalton, N2 O4 is a colorless solid, turning brown by dissociation into NO2 upon warming up, liquid at ambient temperature, melting point −11.2 ∘ C, boiling point 21.15 ∘ C, N2 O4 formed in the solid state only; at melting point and higher, more and more NO2 is formed. N2 O4 reacts with potassium iodide (KI) in the following manner:

4.5 Nitrite and nitrate in meat products 4.5.1 Concentration in meat products The oxidation of nitrite to nitrate in meat also explains why nitrate will be present at considerable concentrations in meat products to which only nitrite has been added. Figures 4.4 and 4.5 show the nitrite and nitrate concentrations of German meat products. Emulsion-type and cooked sausages and cooked hams are manufactured only with sodium nitrite, but contain a mean 20–30 mg nitrate/kg, as noted in Table 4.2. In most cases, the level of nitrite in the finished product is lower than that of nitrate, at a median concentration of 60 mg nitrite/kg (Figure 4.4), and these possess higher nitrate concentrations. In the raw products, nitrate may have been added; in cooked (e.g., liver and blood sausages), the ingoing nitrite is apparently strongly oxidized to nitrate by the meat’s enzyme systems or metal ions, due to their high pH values of between 6.0 and 6.8. For roughly 50 years, the employment of ascorbic acid, ascorbate, or isoascorbate (erythorbate) in cured meat formulations has been common practice in industry. Ascorbic acid and its derivatives are cure accelerators that facilitate the conversion of nitrite to NO. They are added to meat batters at ∼500 mg/kg. Ascorbates and erythorbates are reducing agents with antioxidative activity, and they may also sequester oxygen (Figure 4.6). In this way, they retard the oxidation of NO to NO2 and the formation of nitrate. Furthermore, erythorbate seems to react with nitrite or one of its metabolites and helps maintain cured color during product storage. Dahn et al. (1960), Fox & Ackerman (1968), and Izumi et al. (1989) showed that ascorbate reacts with nitrite and binds the resulting NO. Nitrite is reduced to NO, and the ascorbate is oxidized to dehydroascorbate. The bound NO seems to be able to react as NO with other meat ingredients. Ascorbate is also added, to reduce the formation of N-nitrosamines; this will be discussed later.

−1 5 2 0 4 + → + + 2KNO3 2NO I2 2N2 O4 2KI Iodide is oxidized to I2 , NO2 is oxidized to nitrate and then reduced to NO. For this reason, the addition of iodide as an iodine-fortifying substance to salt is not possible; Iodate (IO3 − ) must be used instead.

4.4.2 Nitrite and nitrate in meat If nitrite is added directly to meat, the salt dissolves easily, due to its good solubility in the aqueous portion of the meat matrix at ∼pH 5.5. Because the pKa of HNO2 is 3.37, at a pH of 3.37 ∼50% of the acid is dissociated. So, at pH 5.5, it can be expected that about 99% of the nitrite exists as its anion, NO2 − (Figure 4.2). The small quantity of undissociated HNO2 is in equilibrium with its anhydride, dinitrogen trioxide (N2 O3 ), which again is in equilibrium with the two oxides of NO and NO2 (Figure 4.3). NO2 can readily react with water. In sum, this means that one HNO2 and one HNO3 molecule are generated from two HNO2 molecules (Figure 4.3). Furthermore, the NO molecule itself can easily be oxidized to NO2 in the presence of molecular oxygen. This means there is an oxygen-sequestering and thus antioxidative action of nitrite in meat batters or hams. Interestingly, this fact is mentioned as a footnote in European Parliament and Council (2006). Metal ions act as catalysts and accelerate the oxidation process. Nitrate added to meat will fully dissociate into Na+ /K+ + NO3 − . No detectable quantity of undissociated HNO3 will be found.

Meat with100 ppm (mg∕kg) of nitrite added = 1.45 × 10−3 M Na+ + NO2 − + H+ ⇆ HNO2 + Na+ −6

pH of meat at 5.5 = 3 × 10 M of H

(a) +

pKa of nitrous acid = 3.37; K = 4.27 × 10−4 So, reaction (a) lies > 99% to the left of the equation at pH 5.5 Figure 4.2 Chemical state of nitrite in meat homogenates.

2HNO2 ⇆ N2 O3 + H2 O N2 O3 ⇆ NO + NO2

Overall Figure 4.3 Reaction of nitrous acid and its derivatives.

NO + 1∕2 O2

→ NO2

2NO2 + H2 O

→

HNO2 + HNO3

2HNO2 + 1∕2 O2 →

HNO2 + HNO3

4

Principles of Curing

23

70 emulsion type N=109 cooked sausage N=50 cooked ham N=33 raw sausage N=43 raw ham N=17

60 % of total

50 40 30 20 10 0 80

concentration of nitrite (mg/kg)

Figure 4.4 Residual nitrite levels (mg/kg) in selected German meat products from 1996 to 2001. Source: Adapted from Dederer, pers. comm.

% of total

emulsion type N=109 cooked sausage N=50

cooked ham N=33 raw ham N=17 raw sausage N=43

45 40 35 30 25 20 15 10 5 0 80

concentration of nitrate (mg/kg)

Figure 4.5 Nitrate levels (mg/kg) in selected German meat products from 1996 to 2001. Source: Adapted from Dederer, pers. comm. Table 4.2 Nitrite and nitrate concentrations in selected German meat products (2003–2005). Year

n

Median concentration (mg/kg) Nitrite

Emulsion-type sausage

Raw sausage Raw ham Liver/blood sausage (cooked sausage)

2003 2004 2005 2003–2005 2003–2005 2003–2005

30 32 29 15 14 16

13.2 12.7 19.9 17.9 19.2 12.1

Nitrate 23.4 20.5 30.0 59.2 16.9 43.3

Source: Adapted from Dederer, pers. comm.

Ascorbate and myoglobin are not the only chemicals to react with nitrite derivatives; amino acids (Figure 4.7) and unsaturated fatty acids can do so as well. These products are rather unstable and either release NO or are oxidized to NO2 and/or nitrocompounds. Such reactions of NO with other substances are another reason for the low residual amounts of nitrite detected in ready-to-eat meat products. Following the reported reactions, it can be assumed that the concentration of nitrate in a sausage to which only nitrite was added is related to the ingoing nitrite content. Figure 4.8 shows that with emulsion-type sausages (only nitrite curing salt was used), the residual levels of nitrite and nitrate exhibit

no relationship above 20 mg residual nitrite/kg. There is no generally recognizable increase of nitrate with increasing residual amounts of nitrite. Without nitrite addition, a residual amount of nitrate probably results from the water or ice added to the formulation (0–50 mg nitrate/L).

4.5.2 Changes with time of storage When does the nitrite in the product disappear? Table 4.3 provides some data from Kudryashov (pers. comm.) of the V.M. Gorbatov All-Russian Meat Research Institute. The largest decrease is observed during manufacture up to the end of the heating process. This early

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Handbook of Fermented Meat and Poultry

HO

O

OH

O

+ 1/2 O2

+ H2O O

O O

O

OH

OH OH

OH ascorbic acid

dehydroascorbic acid

Figure 4.6 Oxygen sequestration by ascorbate (ascorbic acid). O

O

HS

N

OH + NO

NH2

O

S

OH NH2

cysteine

S-nitrosocysteine O

O

NH2

HO

N

OH + NO

OH

O NH2

HO

tyrosine

3-nitrosotyrosine O

O

OH

OH NH

+ NO

N N

proline

O

nitrosoproline

+ CO2 N

O N

nitrosopyrrolidine

Figure 4.7 Reactions of nitric oxide (NO) with selected α-amino and imino acids.

Nitrite Concentration, mg/kg

loss usually exceeds 65%, and is independent of the ingoing nitrite concentrations. Within 20 days of cold storage, the level drops further to a third of the concentration detected after heating. The disappearance continues up to 60 days of cold storage. Table 4.4 confirms the findings. It also shows that a higher pH value helps to retard the disappearance of nitrite. Moreover, it confirms

the results of Table 4.3, which show that the nitrate level is already high at day 0 after heating. Nitrate concentrations also fall with time of storage; however, this reduction is slower with increasing pH. Table 4.5 reports the influence of different heat treatments in meat homogenates; 100 mg nitrite/kg was added to muscles with varying pH, and the homogenate was either mildly heated (pasteurized) or sterilized. The nitrite and nitrate levels were measured immediately after heating and then 12 days into storage. The results show that the higher the heating, the greater the loss of nitrite. The formation of nitrate is also reduced. A higher pH value and/or a different muscle type show less nitrite loss and a higher nitrate concentration. The addition of ascorbate and polyphosphate indicates that the disappearance of nitrite is accelerated by the presence of ascorbate in the raw batter (Table 4.6). Thermal processing to 80 ∘ C for 7 minutes leads to a slower loss of nitrite. Heating for an additional 1 hour at 70 ∘ C retards the loss even longer. This is likely due to the inactivation of microorganisms and of enzymes by heat. With added ascorbate, and even more so with polyphosphates, retardation by heating is also observed. The main loss of nitrite in meat products occurs during the heating step. The application of high pressure up to 800 MPa to cured meats can be employed to inactivate microorganisms, and by this process, the temperature never exceeds 35 ∘ C. After ultra-high pressure (UHP) treatment, residual nitrite analyses reveal that ∼20% of the ingoing nitrite is oxidized to nitrate, but the sum of the residual nitrite and nitrate levels totals nearly the amount of nitrite originally added (Table 4.7). During storage, the nitrite level decreases to ∼50% of the ingoing quantity, while the nitrate level increases to ∼40%. Even at 21 days of storage, the sum of nitrite plus nitrate is ∼90% of the ingoing quantity of nitrite. In comparison to the results of Tables 4.3–4.5, these findings indicate that only a small amount of nitrite reacts with other substances besides oxygen to form nitrate on application of high pressure. The reason for this observation is unknown. In all cases described here, nitrite is partially oxidized to nitrate. In many experiments (see Tables 4.4, 4.5, and 4.7), roughly 10–40% of the ingoing nitrite is so oxidized. As already mentioned, this fact has been known for decades. Only for the results of Table 4.7 does the sum of nitrite plus nitrate add up to ∼90% or more of the added nitrite. Cassens et al. (1978) postulated that nitrite is bound to various constituents in the meat matrix, and provided some percentages based on 15 NO2 tracer studies (Table 4.8).

80 70 60 50 40 30 20 10 0 0

20

40

60

80

100

Nitrite Concentration, mg/kg

Figure 4.8 Concentration of nitrite and nitrate in emulsion-type sausages (n = 48). Source: Adapted from Dederer, pers. comm.

4

Principles of Curing

25

Table 4.3 Residual nitrite levels (mg/kg) determined during storage at 2 ∘ C for an emulsion-type sausage. Storage period

Concentration of sodium nitrite added (mg/kg)

Immediately after heating 20 days 40 days 60 days

75

100

150

200

21.9 7.5 3.6 0.5

30.5 9.3 6.4 0.9

59.5 10.2 7.6 4.0

53.7 15.4 7.7 5.8

Source: Adapted from Kudryashov, pers. comm. Table 4.4 Nitrite decomposition and nitrate formation after sodium nitrite addition to meat at various pH values following heating and storage. pH

5.3

5.8

6.3

Days of storage (after heating)

Nitrite

Nitrate

100 mg/kg added

200 mg/kg added

100 mg/kg added

200 mg/kg added

28 20 5 45 24 13 58 41 31

70 41 18 120 110 21 135 112 90

20 16 9 30 22 8 18 17 10

50 27 20 64 40 17 40 30 22

0 6 12 0 6 12 0 6 12

- c et al. (1980). Source: Adapted from -Dordevi´ Table 4.5 Mean values of nitrite and nitrate content in pasteurized and sterilized groups of homogenates. Homogenate, 100 mg/kg NaNO2 added M. longissimus dorsi pH 5.8 M. quadriceps femoris pH 6.15

Heat treatmenta

P S P S

After heat treatment

After 12 days at 2–4 ∘ C

NaNO2 mg/kg

NaNO3 mg/kg

NaNO2 mg/kg

NaNO3 mg/kg

38.6 12.9 49.2 15.6

27.4 13.1 35.8 19.4

10.9 3.5 26.7 7.4

7.9 6.0 12.8 9.8

pasteurization at 75 ∘ C; S, sterilization at >110 ∘ C. - c et al. (1980). Source: Adapted from -Dordevi´

a P,

4.5.3 Natural, “nitrate/nitrite-free” cured meat products Due to the negative perceptions of nitrite-cured meats held by some consumers, there has been an interest of late in so-called “nitrate/nitrite-free” natural meat products. Any traditionally cured product produced in the United States that does not include the addition of a “chemically-derived” form of nitrite is labeled as uncured. The addition of nitrate/nitrite to meat products is responsible for many of the distinctive properties of cured meats: it develops a characteristic color and flavor, for which there is no

known substitute; without it, natural processed meat products appear brown and their flavor is less desirable. 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, but the statement “no nitrate or nitrite added” must be placed adjacent to the product name. Such products do exist in the marketplace, but are not that popular. In order to circumvent nitrite regulation and labeling issues, in the late 1990s a group of products with traditional cured-meat characteristics were prepared through the use of sea salt and

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Handbook of Fermented Meat and Poultry

Table 4.6 Approximate number of days required for the residual nitrite level to fall below 10 mg/kg in a pork slurry of pH 5.5–6.2 with 2.5–4.5% sodium chloride at a storage temperature of 15 ∘ C (n = 5). Nitrite added (mg/kg) Unheated days

Heat treatment 80 ∘ C/7 minutes days

80 ∘ C/7 minutes + 70 ∘ C/1 hour days

(i) No further addition 100 5 12 200 10 12 300 21 21 (ii) Ascorbate (1000 mg/kg) 100 5 9 200 5 9 300 5 21 (iii) Ascorbate (1000 mg/kg) + polyphosphate 0.3% (w/v) 100 5 10 200 10 21 300 5 5

63 68 >168 10 9 48 21 21 12

Source: Adapted from Gibson et al. (1984). Reproduced with permission of Wiley.

Table 4.7 Nitrite and nitrate concentrations in a Lyoner (an emulsion-type sausage, 72 ppm nitrite added) after UHP application and storage of the unheated batter. Days

0

Treatment Control 400 MPa 600 MPa 800 MPa

7

14

21

0

Nitrite level (mg/kg) 54.3 53.3 53.0 52.3

47.1 46.4 44.8 44.7

42.8 41.5 40.7 41.6

7

14

21

0

Nitrate level (mg/kg) 39.3 37.7 37.2 37.7

15.15 15.8 16.15 17.5

19.5 22 23.85 23.95

23.8 25.9 27.35 26.55

7

14

21

Nitrite + nitrate level (mg/kg) 26.2 26.95 29.1 26.6

69.45 69.05 69.1 69.75

66.55 68.4 68.65 68.65

66.6 67.4 68.0 68.15

65.5 64.6 66.25 64.25

Source: Adapted from Ziegenhals, pers. comm.

vegetable juice/concentrate/powder high in naturally-occurring nitrates (e.g., celery has nitrate levels typically ranging from 1500 to 2800 ppm, while 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, Staphylococcus carnosus). The nitrate-reducing bacteria convert nitrate to nitrite and thereby “indirectly” cure the meat product. The labeling of these products as uncured is viewed by some consumers as incorrect at best and deceptive at worst (Sebranek et al., 2012); such labeling is required for most naturally cured items, in order to meet USDA requirements. Even though modern technology has developed concentrated vegetable extracts from celery (Apium graveolens var. dulce) with nitrate concentrations of ∼3% and efficient strains of nitrate-reducing bacteria, the process still requires an incubation step at 38–42 ∘ C to allow adequate formation of nitrite by the culture in the meat matrix prior to thermal processing. In order to overcome the incubation period in real-time processing, processors began to incubate the celery juice with the culture prior to its addition to the

meat product (Krause et al., 2011; Terns et al., 2011). This practice was extended to suppliers of the celery concentrate, who began to market preconverted nitrite from nitrate. Processors today use both preconverted nitrates (already converted to nitrite) from celery powder and unconverted celery powder with a starter culture containing a nitrate-reducing enzyme. This practice has resulted in a category of processed meats in the United States that is labeled confusingly and perhaps even misleadingly to the consumer. Moreover, the protection against spore germination of Clostridium botulinum afforded by the addition of nitrite to meat products is potentially compromised in these uncured products, because the conversion of the nitrate present in celery to nitrite is not a well-controlled reaction. Sebranek et al. (2012) quite correctly point out that the addition of a celery concentration or powder containing 3.0% (30 000 ppm) nitrate to meat at a typical use concentration of 0.3% will result in 90 ppm of nitrite, at most, in the meat product (assuming a 100% conversion of nitrate to nitrite, which is not realistic). Furthermore, because preconverted celery products contain roughly 15 000–20 000 ppm nitrite, the

4

Table 4.8 Forms of nitrite and its reaction products detected in meat products. Bound to/form

Nitrite Nitrate Myoglobin Bound to –SH Bound to lipids Bound to proteins Gas Total

Percentage of total 5–20 1–10 5–15 1–15 1–15 20–30 1–5 ∼70

Percentage of totala

10–40a

90

a Assumption

by Honikel according to results presented in Figures 4.4, 4.5, and 4.6. Source: Adapted from Cassens et al. (1978). Reproduced by permission of Oxford University Press.

addition of 0.3% of this to a meat formulation is equivalent to only 45–60 ppm of nitrite. This raises questions over the product’s microbiological safety in vacuum-packed bags. For this reason, the USDA is very concerned about chilling rates for finished packaged products. A processor manufacturing a “naturally” cured product must follow the restrictive chilling regime outlined in Appendix B of the USDA meat regulations. For the most part, the processing procedures involved in natural curing are similar to those using sodium nitrite. Nitrate is more stable than nitrite, so sufficient time to allow the starter culture to reduce exogenous nitrate to nitrite is required. If preconverted nitrite is not being used, the time required depends on a number of factors, including temperature, pH, the growth cycle of the starter culture (i.e., number of microorganisms), and the 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., the 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 being added 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 the need to include the added water on the label. The finished product, however, must bear a label disclaimer such as “no nitrates or nitrites added, except for that which occurs naturally in celery juice powder.” Finally, to maintain the image of “naturally cured” products, processors often include a clean-label alternative to sodium erythorbate as a cure accelerator in their formulations. As described earlier, ascorbic acid/sodium ascorbate/sodium erythorbate facilitates the conversion of nitrite to NO for cured color development. Typical natural sources of ascorbic acid employed by the industry include cherry powder and acerola (Malpighia emarginata DC). Acerola, also known as Barbados cherry and West Indian cherry, contains markedly high levels of ascorbic acid, typically 4–5%, as well as a number of phenolics and polyphenolics; these provide potent antioxidants in the fruit extracts/powders (Mezadri et al., 2008).

Principles of Curing

27

4.6 Nitrosomyoglobin (NOMb) The pink to red color of thermally-processed cured meat products is one of the important effects stemming from the addition of nitrite to meat. This color is developed through a number of complicated reaction steps, culminating in the formation of nitrosomyglobin (Fe2+ ) (Pegg & Shahidi, 2000). Myoglobin is a globular protein that is made up of a single polypeptide chain consisting of ∼153 amino acids and a prosthetic heme group, an iron(II) protoporphyrin-IX complex (Figure 4.9). Myoglobin exists in muscle tissue in three states: (i) one in which the cofactor heme binds different ligands; (ii) one in which the iron exists in the ferrous (Fe2+ ) state; and (iii) one in which the iron exists in the ferric (Fe3+ ) state. In native myoglobin, the heme moiety is held in a cleft of the globin protein by a coordinate bond between the imidazole nitrogen of the proximal histidine residue and the Fe(II) ion, and by several nonpolar and hydrogen-bonding interactions at the porphyrin periphery. In the purple–red deoxy form, the Fe2+ in the porphyrin cofactor of myoglobin does not bind any ligand, except perhaps a water molecule. In the presence of air, oxygenation takes place and the porphyrin binds with O2 and becomes a bright cherry red. The iron ion of oxymyoglobin (MbO2 ) exists in the reduced Fe2+ state, but over time oxygen itself and other oxidizing agents (such as nitrite) oxidize the Fe2+ to Fe3+ (Figure 4.10), generating metmyoglobin (metMb), which is brown in appearance. The pigments dexoy-myoglobin (Mb), MbO2 , and metMb can all be found in fresh meat. In the muscle of a live animal, there is very little metMb, but its content increases post mortem with the disappearance of O2 , except when the meat product is modified atmosphere packaging (MAP)-packed with high O2 . The three states of myoglobin each have distinctive absorbance spectra in the visible region of the electromagnetic spectrum between 400 and 700 nm. Because the three exist in a kind of equilibrium with one another, the spectra have an isobestic point at 𝜆 = 525 nm, where all three absorption curves cross each other.

OH N

N

O

Fe N

N OH O

iron(II) protoporphyrin IX

Figure 4.9 Iron(II) protoporphyrin IX—the heme moiety in myoglobin.

3+

2H+ + NO2 − + Fe2+ –myglobin → 2+

H2 O + NO + Fe3+ –myoglobin (metmyoglobin, metMb) Figure 4.10 Reaction of nitrite with myoglobin in meat at pH 5.5.

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Handbook of Fermented Meat and Poultry

MbO2

MetMb

but the red NO–porphyrin ring system (often called mononitrosyl hemochromogen or nitrosohemochromogen) remains intact, and it is found in meat products heated to 120 ∘ C. The heat-stable red color will change in appearance as a result of bacterial spoilage and will fade upon exposure to UV light. Nearly 10 years ago, the riddle concerning the red color of non-nitrite/nitrate-cured raw hams such as Parma ham and jamón ibérico was solved by Japanese researchers using electrospray ionization high-resolution mass spectrometry (Wakamatsu et al., 2004a). Since then, various authors have confirmed the finding and shown that the ferrous ion in the porphyrin ring of heme is exchanged with Zn2+ during the long ripening period, which gives the products a stable bright red color. Nitrite addition prevents this exchange from happening (Adamsen et al., 2006; Møller et al., 2003; Parolari et al., 2003; Wakamatsu et al., 2004b).

Mb

MbNO

450 470 490 510 530 550 570 590 610 630 nm

Figure 4.11 Visible spectra of various chemical forms of myoglobin. Mb, deoxy-myoglobin; MbO2 , oxymyoglobin; MetMb, metmyoglobin; MbNO, nitrosomyoglobin.

metmyoglobin (Fe3+ ) + NO + ascorbate → NO–myoglobin (Fe2+ ) + dehydroascorbate Figure 4.12 Formation of nitrosomyoglobin (NOMb).

Based on developed equations, the absorbance at this wavelength can be used to determine the percentage of each form of myoglobin in the meat at a given point. Nitrosomyoglobin (NOMb) has a spectrum with similar maxima to those of MbO2 (Figure 4.11). Both O2 and NO are diatomic and paramagnetic molecules. Carbon monoxide, CO, a similar diatomic molecule, also binds tightly to myoglobin. In some countries, MAP packaging of ready-case meat products with 1–2% CO is permitted. Through the action of endogenous reducing enzymes of the meat matrix or chemical reactions with a reductant like erythorbate, the Fe3+ is reduced to Fe2+ (Figure 4.12). The NO generated from N2 O3 can bind to myoglobin (Fe2+ ), which forms a heat-stable NOMb. MbO2 is not heat-stable and dissociates, allowing the meat to turn gray or brown. On heating, the protein moiety of NOMb denatures,

4.7 N -nitrosamine formation During the 1970s, discussions arose in the United States concerning the formation of N-nitrosamines in nitrite-cured meat products, especially fried bacon. Fiddler et al. (1978) showed that bacon and its cookout on frying contained considerable amounts of N-nitrosopyrrolidine and some N-nitrosodimethylamine. N-nitrosamines constitute a family of potent carcinogens that are formed readily from a diverse set of nitrogen-containing compounds and from nitrite and its derivatives. In meat, they are produced by the reaction of secondary amines with nitrite at high temperatures, according to the reaction schemes depicted in Figure 4.13. A number of prerequisites must be met in order for N-nitrosamines to be generated: (i) amines must be present—in fresh meat, trivial quantities of amines can be found, including creatine, creatinine, proline, hydroxyproline, and decarboxylated amino acids; by and large, aging and the fermentation of meat products will generate more; (ii) secondary amines must exist to form stable N-nitrosamines (Figure 4.13)—primary amines are immediately degraded to alcohol and nitrogen, while tertiary amines cannot react with nitrite at all; unlike in fish, most amines in meat are primary amines, derived from α-amino acids; and (iii) the pH must be sufficiently low to produce NO+ , or else metal ions must be engaged to form NO+ (Figure 4.13).

NaNO2 + H+ → HNO2 + Na+ HNO2 + H+ → NO+ + H2 O 2HNO2 → N2 O3 + H2 O N2 O3 → NO + NO2 NO + M+ → NO+ + M primary amine

RNH2 + NO+ → RNH–N = O + H+ → ROH + N2

secondary amine

R2 NH + NO+ → R2 N–N = O + H+

tertiary amine

R3 N + NO+ → no N − nitrosamine formation

Figure 4.13 Reaction pathways for the formation of N-nitrosamines in cured meat products. M and M+ represent transition-metal ions such as Fe2+ and Fe3+ .

4

Table 4.9 N-nitrosodimethylamine content (μg/kg) in selected food products. Food

Beer Pizza Meat products Milk products

n

195 57 17 6

Content >0.5

Minimum

3 6 0 0

0.5 0.5 0 0

Maximum 1.2 8.7 0 0

Source: Adapted from Deierling et al. (1997). Reproduced with permission of WILEY-VCH Verlag GmbH & Co. KGaA.

When heated meat products are prepared from fresh meat (chilled or frozen), no amines are available. In raw nitrate-cured meat products, the nitrite concentration is rather low (see Figure 4.4), so the formation of NO+ is quite unlikely. In products heated above 130 ∘ C, N-nitrosamines can form. Frying of bacon, grilling of cured sausages, and frying of cured meat products such as pizza toppings may all provide the conditions leading to N-nitrosamines formation. Table 4.9 shows the results of an investigation into the N-nitrosamine content of such foods by Deierling et al. (1997); in German foods, only beer and pizza exhibit N-nitrosodimethylamine at detectable μg/kg levels. Thus, N-nitrosamines occur only in minute quantities, and they are easily avoidable by proper frying, grilling, and pizza baking. Jakszyn et al. (2004) prepared a database of N-nitrosamine levels in foods, together with levels of heterocyclic amines and polycyclic aromatic hydrocarbons.

4.8 Conclusion The curing of meat is a process that predates written history. The main curing agents, nitrite and nitrate, react with components of the meat matrix and added adjuncts because of the varying oxidation status of nitrogen in these additives. Nitrite is multifunctional, in that it is responsible for the typical color and flavor associated with cooked cured meat, it acts as an antioxidant, preventing the development of warmed-over flavor, and it retards the formation of the Clostridium botulinum toxin in combination with NaCl in vacuum-packaged products. The positive effects attributed to nitrite and nitrate addition in meat products overwhelm the low possibility of N-nitrosamine formation. Moreover, the intake of curing agents (i.e., nitrate and nitrite) from meat products in the daily diet is minor (only a few per cent) in comparison with other foods.

References Adamsen CE, Møller JKS, Laursen K, Olsen K, Skibsted LH. 2006. Zn-porphyrin formation in cured meat products: effect of added salt and nitrite. Meat Science, 72, 672–679. Das Bundesgesetzblatt. 1982. Verordnung über Fleisch und Fleischerzeugnis (Fleischverordnung) in der Fassung der Bekanntmachung vom 21. Bundesgesetzblatt I, 3, 89–101. Cassens RG, Ito T, Lee M, Buege D. 1978. The use of nitrite in meat. Bioscience, 28, 633–637.

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Dahn H, Loewe L, Bunton CA. 1960. Über die Oxydation von Ascorbinsäure durch saltpetrige Säure. Teil VI: Übersicht und Diskussion der Ergebnisse. 18. Mitteilung über Reduktone und 1,2,3-Tricarbonylverbindungen. Helvetica Chimica Acta, 43, 320–333. Deierling H, Hemmrich U, Groth N, Taschan H. 1997. Nitrosamine in Lebensmitteln. Lebensmittelchemie, 51, 53–61. - c V, Vuksan B, Radeti´c P, -Durdica - H, Mitkovi´c M. 1980. Prilog -Dordevi´ ispitivanju uticaja pojedinih faktora na promene sadržaja nitrita u mesu. Tehnologija Mesa 21, 10, 287–290. European Parliament and Council. 1995. European Parliament and Council Directive 95/2/EC. Official Journal of the EU, L61, 18.3.1995, Food Additives Other than Colours and Sweeteners, p. 1–40. European Parliament and Council. 2006. Directive 2006/52/EC of the European Parliament and of the Council of July 5, 2006, amending Directive 95/2/EC on Food Additives Other than Colours and Sweeteners and Directive 95/35/EC on Sweeteners for Use in Foodstuffs, Official Journal of the EU, L204, 26.7.2006. FDA. 2012. United States Food and Drug Administration, Code of Federal Regulations (USA). Title 21, Volume 3, Revised April 1, Food and Drugs. Food Preservatives, 21CFR § 172.175. Fiddler W, Pensabene JW, Piotrowski EG, Phillips JG, Keating J, Mergens WJ, Newmark HL. 1978. Inhibition of formation of volatile nitrosamines in fried bacon by the use of cure-solubilized α-tocopherol. Journal of Agricultural and Food Chemistry, 26, 653–656. Fox JB Jr,, Ackerman SA. 1968. Formation of nitric oxide myoglobin: mechanisms of the reaction with various reductants. Journal of Food Science, 33, 364–370. Gibson AM, Roberts TA, Robinson A. 1984. Factors controlling the growth of Clostridium botulinum types A and B in pasteurized cured meats. VI. Nitrite monitoring during storage of pasteurized pork slurries. International Journal of Food Science & Technology, 19, 29–44. Haldane J. 1901. The red colour of salted meat. Journal of Hygiene, 1901, 115–122. Hoagland R. 1910. The action of saltpeter upon the color of meat. In: 25th Annual Report of the Bureau of Animal Industry, US Department of Agriculture. Government Printing Office, Washington, DC, pp. 301–316. Hoagland R. 1914. Coloring matter of raw and cooked salted meats. Journal of Agricultural Research, 3, 211–225. Ignarro LJ. 1990. Biosynthesis and metabolism of endothelium-derived nitric oxide. Annual Review of Pharmacology and Toxicology, 30, 535–560. Izumi K, Cassens RG, Greaser ML. 1989. Reaction of nitrite with ascorbic acid and its significant role in nitrite-cured food. Meat Science, 26, 141–153. Jakszyn P, Agudo A, Ibáñez R, García-Closas R, Pera G, Amiano P, González CA. 2004. Development of a food database of nitrosamines, heterocyclic amines, and polycyclic aromatic hydrocarbons. Journal of Nutrition, 134, 2011–2014. Kisskalt K. 1899. Beiträge zur Kenntnis der Ursachen des Rothwerdens des Fleisches beim Kochen, nebst einigen Versuchen über die Wirkung der schwefligen Säure auf die Fleischfarbe. Archiv für Hygiene, 35, 11–18. Krause BL, Sebranek JG, Rust RE, Mendonca A. 2011. Incubation of curing brines for the production of ready-to-eat, uncured, non-nitrite-or-nitrate-added, ground, cooked and sliced ham. Meat Science, 89, 507–513. Lehmann KB. 1899. Über das Haemorrhodin, ein neues weitverbreitetes Blutfarbstoffderivat. Sitzungs-Berichte der Physikalisch-medicinischen Gesellschaft zu Würzburg, 48, 57–61. Lovtidende. 1995. Danish regulation (1995 A), p. 5571 of 18.12.1995. Lowenstein CJ, Snyder SH. 1992. Nitric oxide, a novel biologic messenger. Cell, 70, 705–707. Lüscher TF. 1990. Endothelial control of vascular tone and growth. Clinical and Experimental Hypertension. Part A, Theory and Practice 1990, 12, 897–902.

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Lüscher TF. 1992. Endogenous and exogenous nitrates and their role in myocardial ischaemia. British Journal of Clinical Pharmacology, 34, 29S–35S. Marletta MA. 1989. Nitric oxide: biosynthesis and biological significance. Trends in Biochemical Sciences, 14, 488–492. Mezadri T, Villaño D, Fernández-Pachón MS, García-Parrilla MC, Troncoso AM. 2008. Antioxidant compounds and antioxidant activity in acerola (Malpighia emarginata DC.) fruits and derivatives. Journal of Food Composition and Analysis, 21, 282–290. Møller JKS, Adamsen CE, Skibsted LH. 2003. Spectral characterisation of red pigment in Italian-type dry-cured ham. Increasing lipophilicity during processing and maturation. European Food Research and Technology, 216, 290–296. Moncada S, Palmer RMJ, Higgs EA. 1991. Nitric oxide: physiology, pathophysiology, and pharmacology. Pharmacological Reviews, 43, 109–142. Nathan C. 1992. Nitric oxide as a secretory product of mammalian cells. FASEB Journal, 6, 3051–3064. Parolari G, Gabba L, Saccani G. 2003. Extraction properties and absorption spectra of dry cured hams made with and without nitrite. Meat Science, 64, 483–490. Parthasarathy DK, Bryan NS. 2012. Sodium nitrite: the “cure” for nitric oxide insufficiency. Meat Science, 92, 274–279.

Pegg, RB, Shahidi F. 2000. Nitrite Curing of Meat. The N-Nitrosamine Problem and Nitrite Alternatives. Trumbull, CT: Food & Nutrition Press. Polenske E. 1891. Über den Verlust, welchen das Rindfleisch und Nährwert durch das Pökeln erleidet, sowie über die Veränderungen Salpeter-haltiger Pökellaken. Arbeiten aus dem Kaiserlichen Gesundheitsamte, 7, 471–474. Schuddeboom LJ. 1993. Nitrates and Nitrites in Foodstuffs. Council of Europe Press, Publishing and Documentation Service. Sebranek JG, Jackson-Davis AL, Myers KL, Lavieri NA. 2012. Beyond celery and starter culture: advances in natural/organic curing processes in the United States. Meat Science, 92, 267–273. Stamler JS, Singel DJ, Loscalzo J. 1992. Biochemistry of nitric oxide and its redox-activated forms. Science, 258, 1898–1902. Terns MJ, Milkowski AL, Claus JR, Sindelar JJ. 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. Wakamatsu J, Nishimura T, Hattori A. 2004a. A Zn-porphyrin complex contributes to bright red color in Parma ham. Meat Science, 67, 95–100. Wakamatsu J, Okui J, Ikeda Y, Nishimura T, Hattori A. 2004b. Establishment of a model experiment system to elucidate the mechanism by which Zn-protoporphyrin IX is formed in nitrite-free dry-cured ham. Meat Science, 68, 313–317.

5

Principles of Drying Raúl Grau,1 Ana Andres,2 and José M. Barat1 1

Food Science and Technology Department, Universitat Politècnica de València, Valencia, Spain 2 Institute of Food Engineering for Development, Food Science and Technology Department, Universitat Politècnica de València, Valencia, Spain

5.1 Introduction Food drying is one of the oldest methods of preserving food for later use. It is simple, safe, and easy to learn. It slows the action of enzymes, because it removes moisture so that the food shrinks and becomes lighter; it removes enough moisture that bacteria, yeasts, and molds can’t grow (Gould, 1920). Sun drying is the most ancient method, and even nowadays it is still used for fruit drying (Gould, 1920). Drying is used in the food industry as a method for preserving a large amount of product. The great weight and volume reduction of the dried products leads to an important reduction of storage and shipping costs. It also affects the sensory properties of the food (Baker, 1997; Heldman & Hartel, 1997). Since the presence of water in foods directly affects their spoilage, removing water will reduce the possibility of biological alteration, as well as affecting the kinetics of others spoilage mechanisms. Removing water from a food involves two important problems, however: first, it risks altering the nutritional and sensorial qualities, and second, it is sometimes a highly energy-intensive process. The lack of selectivity in water-removal processes can produce an important loss of aromas, especially when working at vacuum pressures (Bimbenet & Lebert, 1990).

5.2 Basic principles of drying Drying and/or dehydration is a method of food preservation in which moisture is evaporated by exposure of the product to air with a lower water activity than the product itself. It is governed by the fundamental principles of physics and physical chemistry. Heat can either be applied externally or generated internally by microwave or radio-frequency energy, which enhances evaporation and drives trapped moisture to the surface. Efficient drying is only obtained by heat that penetrates to the center of the food, forcing moisture to the surface for evaporation or to a lower-vapor pressure area of the food particle (Mujumdar, 1995). Different types of dryer are used for different methods of heating: convection, radiation, dielectric, or conduction. The most common driers used in the food industry are the convective or air driers,

which work either continuously or in batches, depending on the type of product. Designing a drier requires an understanding of the mechanism and kinetics of the food product to be dried; that is, it is necessary to establish the quantitative relationships between the time of the process and the drying conditions (Bimbenet & Lebert, 1990). The variables that determine the time of drying of a food product are related to (i) the drying (temperature, velocity, humidity, flow characteristics, etc.) and (ii) the product (moisture, size, shape, structure, etc.). For this reason, it is necessary to determine the drying curves (moisture versus time) for fixed experimental conditions experimentally. The experimental conditions must be as close as possible to the industrial device in terms of heat-transfer mechanism, air flow, product density, and so on. In other words, the industrial process must be imitated (Baker, 1997). Different types of experimental data are necessary, some of them related to quality aspects (evolution of color, shape and size, texture, flavor, etc.) and others to the kinetics of the process (evolution of the mass and moisture throughout the drying process). Determination of the evolution of moisture in a food product under a drying process gives the drying curve. Figure 5.1 shows a typical drying curve for a product with high moisture; three zones can be distinguished, corresponding to three typical steps in a drying process: induction period, constant-rate period, and falling-rate period. The induction period corresponds to the beginning of the drying process, during which a heat transfer occurs from the air to the product, increasing the surface temperature up to the wet-bulb temperature. The duration of this period depends on many factors, but it is negligible compared to the following periods, and for this reason it is not taken into account for design purposes. When the surface reaches the wet-bulb temperature, the total amount of heat from the air is used to evaporate water, and since the rate of evaporation is lower than the rate of water transport to the surface, the drying rate is constant (constant-rate period). In this period, it is assumed that the surface remains wet and behaves like a liquid. As the drying process proceeds, the product dries and the water transport rate towards the surface decreases. This is the end of the constant-rate period and the product moisture at this point is known as critical moisture content (Xc ), while the time needed to reach this point is called the critical time (tc ).

Handbook of Fermented Meat and Poultry, Second Edition. Edited by Fidel Toldrá. © 2015 John Wiley & Sons, Ltd. Published 2015 by John Wiley & Sons, Ltd.

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Handbook of Fermented Meat and Poultry

moisture A: Induction period B: Constant-rate period C: Falling-rate period xc

Xe A B

C time

tc

Figure 5.1 Typical drying curve.

The constant-rate period is the drying step in which the most important changes in terms of volume reduction take place. Internal moisture is more difficult to remove, because it is more tightly bound and is protected by the insulating effect of the already-dried material close to the surface. The water in the center is very difficult to remove; its removal is thus carried out by diffusion. This is the so-called “falling-rate period” or “diffusion period” of drying, in which the water must be diffused from the center outward for evaporation in order to obtain a dried product. The drying rate in this period is very low for a typical diffusion process, and product moisture decreases to reach equilibrium moisture (Xe ), or in other words, the equilibrium of water activity with the surrounding airflow. These typical drying periods can also be explained by taking into account the shape of the sorption isotherm of a high-moisture food product (Figure 5.2). It is well known that the drying rate depends on the driving force in action during the process; that is, the difference between the water activity (aw ) of the product and the aw of the drying air. Another consideration to take into account is that the equilibrium condition is accomplished at the interface; the aw at the product surface equals the aw of the drying air. During the constant-rate period, the aw of the product is near to 1, and as the product dries, big changes in moisture lead to small changes in aw , as can be seen in the isotherm (Figure 5.2). Since aw remains nearly constant, the driving force can be considered constant, as can the drying rate. However, during the falling-rate period, small changes in moisture content lead to big changes in aw .

moisture

Constant-rate period

Falling-rate period

0

aw

1

Figure 5.2 Relationship between the drying periods and the sorption isotherm.

Food properties (composition, structure, etc.) influence the aw parameter, which is greatly related to water distribution in the different food phases and will influence the drying kinetics. For this reason, it is very interesting to know the relationship between aw and equilibrium moisture content (sorption isotherm). The driving force for water evaporation is the aw gradient between the food and the forced hot air, but other properties of drying air will also affect the drying kinetics, as was mentioned before. One of the variables affecting the drying rate is the air velocity; the higher the air velocity, the higher the drying rate. However, above a certain value of air velocity, the drying rate will no longer depend on air velocity, since the factor controlling the drying kinetics is the water diffusion rate from the interior of the product to the surface. Another important process variable is the air relative humidity (RH). As mentioned before, a food product dehydrates when the aw of the air (RH/100) is lower than that of the product, and the difference in the aw values is the main driving force, increasing the drying rate when the aw gradient increases. Nevertheless, if water is removed too fast, the food material may “case harden”; that is, seal up the outer surface area so that the water diffusion from the center outward is hindered. On the other hand, it can be said that the higher the air temperature, the higher the drying rate. The increase in drying temperature mainly affects the diffusivity value inside the product, which usually behaves in accordance with Arrhenius’s law (Trujillo et al., 2007). The increase in temperature also improves the heat transfer on the product surface, where intense heat-transfer mechanisms occur as a consequence of the water phase change from liquid to gas state. Some of the food components, including pigments, vitamins, and so on, are temperature-sensitive, and these quality aspects will limit the maximum air temperature usable in the drying process. In some cases, the drying process has other purposes than the removal of water, allowing some biochemical reactions to develop taste and flavor; this is known as a curing process. Since these reactions are time-dependent, low air temperatures are used. This is the case for fish and meat products, and sometimes a mixture of air and smoke is used to obtain a characteristic smoked flavor.

5.3 Hurdle technology applied to dried meat and poultry products As was stated in the previous section, meat drying was originally used for meat preservation, due to the aw reduction (Doe et al., 1998). If drying should need to be used as a unique meat-preservation technique, the final moisture of the dried product will be very low: below a “comfortable” value, from a sensory point of view. Figure 5.3 shows the aw value limiting the microbial growth and the typical aw of the most common meat products (Garriga et al., 2004; Hoz et al., 2004; IFT/FDA, 2003; Muthukumarasamy & Holley, 2006; Rubio et al., 2006a; Serra et al., 2005; Smith et al., 1989; Soriano et al., 2006). From Figure 5.3, an aw of 0.8 seems to be a reasonable value with which to get a shelf-stable product stored at room temperature. For example, to get this value at room temperature (25 ∘ C) (Figure 5.4) for smoked chicken sausages, the moisture value should be around 24%, which is obviously too low for direct consumption. This is why drying is usually employed in combination with other preserving

5 Principles of Drying

(aw) MICROORGANISMS

aw

0.98 Campylobacter spp. 0.97 Clostridium botulinum type E* 0.97 Shigella spp. 0.97 Yersinia enterocolitica 0.96 Vibrio vulnificus 0.95 Enterohemorrhagic 0.94 Escherichia coli 0.94 Salmonella spp. 0.94 Clostridium botulinum 0.93 Vibrio parahaemolyticus 0.93 Bacillus cereus 0.92 Clostridium perfringens 0.88 Staphylococcus aureus 0.83 Listeria monocytogenes

MEAT PRODUCT

1,00

Fresh meat (0.99)

0,95

Spanish-type dry-cured sausage “Salami” (0.96)

0.90 0.85

Dry cured ham (0.88)

0.80

Italian-type dry-cured meat Proscuittini (0.87)

0.75

Italian-type dry-cured meat Genoa Salami (0.87)

0.70 0.65 0.60

33

Spanish-type dry-cured meat “Cecina león” (0.86) Spanish-type dry-cured sausage “Salchichón” (0.849)

Figure 5.3 aw values limiting the growth of the most common spoilage microorganisms and of some meat products.

5.3.2 Curing

Moisture content (g water/100 g solids) 50°C 36.5 25°C 24

Curing is necessary for an adequate shelf life. The curing process is well known and is explained in detail in Chapter 3. The most active components of the curing salts are the nitrites, which prevent the microbial growth of pathogens like Chlostridium botulinum and Listeria monocytogenes.

5.3.3 Salting

17.5

5°C

0.8 Water activity (aw)

Figure 5.4 Moisture-desorption isotherms of smoked chicken sausages. Source: Adapted from Singh et al. (2001). Copyright 2001, with permission from Elsevier.

techniques, and thus the hurdle-technology principles (Leistner, 1995) are present in most of the meat products developed by means of these techniques. The main preserving techniques, employed in combination, are given in this section.

5.3.1 Refrigeration All of the raw materials are perishable at room temperature in their original form, which is why low temperatures are used during storage, transportation, and processing. In some cases, the use of low temperatures is necessary at the beginning of the drying process, particularly for larger meat sample sizes. The temperature used for meat products varies according to the product, but falls within a narrow range from 3 to 20 ∘ C. When using cold smoking, the maximum temperature increases up to 30 ∘ C. In the case of Spanish cured ham, the product begins to dry during the post-salting stage, and the process temperature is kept close to 3 ∘ C at this point. Further increases of temperature throughout the processing occur associated with the aw decrease until a shelf-stable product is achieved (Barat et al., 2005; Toldrá, 2002).

Salting is always present for meat products. NaCl plays many technological roles: it provides a salty taste and flavor perception, it allows the control of microbial growth and enzymatic activity, and it modifies the adherence and the water holding capacity of the protein matrix. In the case of sausages, NaCl is added during the mixing phase, while for whole meat pieces, it can be added by means of dry or wet salting. The use of dry salting without drainage at a low food/salt ratio will lead to the product being surrounded by a brine; this case is considered a pickling (Barat et al., 2006).

5.3.4 Spicing The use of spices is very frequent in the case of sausages. The addition of spices not only contributes to color and flavor development, but also provides a source of external contamination, an antioxidant effect, and in some cases an inhibition of microbial growth (Careaga et al., 2003; Shelef, 1983; Zaika, 1988).

5.3.5 Fermentation and biopreservation Fermentation is involved in the manufacture of many food products (Adams & Robert-Nout, 2001; Lücke, 1999). Its key point consists in the decrease of the sausage’s pH as a consequence of the conversion of sugar into lactic acid due to the action of bacteria. The decrease of pH improves not only the meat’s preservation but also the drying process, due to the decrease in the water holding capacity of the meat proteins when the pH approaches the isoelectric value. The specific bacteriostatic activity of some of the microorganisms added through the starter culture (e.g. LAB) contributes to the microbial stabilization of the final product (Aymerich et al., 2000; Coffey et al., 1998; Hammes & Hertel, 1998).

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5.3.6 Packaging and storage Vacuum and modified atmosphere packaging (MAP) are the most packaging methods. These techniques employ gas mixtures and packaging materials technology to extend the shelf life of food. For meat products, the atmosphere in the package is modified by causing a vacuum and then replacing the package atmosphere with a gas mixture of oxygen (O2 ) and carbon dioxide (CO2 ), or of nitrogen (N2 ) and CO2 . In dry-cured meat products, the gas mixture most commonly utilized is 0% O2 , 20–35% CO2 and 65–80% N2 (García-Esteban et al., 2004; Rubio et al., 2006b; Valencia et al., 2006).

5.3.7 Smoking Smoke curing is a typical combined treatment, based on the concerted action of enzymes and heat, which promotes protein and lipid changes in the previously salted raw material. The treatment has nutritional implications and affects the sensory quality, safety, and shelf life of the product (due to the bacteriostatic effect of the compounds present in the smoke), but the extension of these changes will depend on many factors, including the type of smoking, the RH, velocity, temperature, density, and composition of the smoke, and the time of smoking (Yean et al., 1998). Today, smoking chambers are air-conditioned rooms used for a variety of meat processes other than just smoking, including curing, drying, cooking, and s on. Various smoking procedures exist: traditional smoking, electrostatic smoking, and treatment with smoke aromas or condensates (Cava-López & Andrés-Nieto, A., 2001).

5.4 Fundamentals of the drying of meat and poultry products The general principles of food drying were introduced in Section 5.2. Some particular aspects must be taken into account when working with meat and poultry products. The protein matrix suffers dramatic changes at a certain temperature in the range 40–80 ∘ C, implying denaturation of the protein. These changes are usually undesirable, except in certain smoked products, where proteins coagulate as a consequence of the high temperatures (Bertram et al., 2006; Stabursvik & Martens, 1980). Drying not only contributes to a decrease of the aw of the product but also affects the hardness and stability of the protein matrix. Another phenomenon associated with the drying process is case hardening (Gou et al., 2005), which implies not only an increase in the hardness of the surface but also a dramatic decrease in the drying rate, and thus leads to a heterogeneous dried product, with a highly dried surface and a poorly dried core. Recent studies have been carried out to correlate the moisture content and texture, in order to characterize the crust formation and thus prevent case hardening by controlling the drying conditions (Beserra et al., 1998b; Gou et al., 2005; Ruiz-Ramírez et al., 2005; Serra et al., 2005). The presence of fat in meat products contributes to a decrease in the drying rate, because of its barrier effect, but it also prevents the food surface from undergoing excessive drying. In fact, in the case of ham drying, a layer of fat is usually applied on the surface in the final

°C, m/s % RH 24 100 21 90 18 80 15 70 12 60 9 50 6 40 3 30 0 20 6780 6800 6820 6840 6860 6880 6900 6920 6940 t (min) T

Va

RH

Figure 5.5 RH changes throughout a typical sausage drying process. Source: Adapted with permission from Comaposada et al. (2004). Eurocarne, pp. 1–13.

processing period, among other reasons in order to prevent drying. The fat content of sausage products ranges widely, from 5 to 70%. The higher the fat content, the lower the drying rate. Another aspect that must be taken into account is that the excessive mincing of fat and lean leads to a phenomenon called smearing, which causes the case to harden and leaves a highly moist core region. One of the strategies followed in industry to prevent case hardening is to fluctuate from lower to higher aw of the air. When the aw of the surrounding air decreases (RH/100), the drying process accelerates, while when it increases, water migrates from the interior to the surface fast enough to increase the surface moisture. Figure 5.5 shows the RH changes throughout a typical sausage drying process. In general, the risk of case hardening increases the higher the demand for water from the product by the air. This demand mainly depends on the air RH and the air speed inside the cabinet. The lower the air RH, the higher the aw gradient between the meat product surface and the bulk air, leading to an increase in the drying rate. The other parameter affecting the drying rate is the air velocity; when the air rate increases, a higher turbulent flow is created in the neighborhood of the product, leading to a decrease of the boundary layer thickness, which also leads to an increase in the effective aw gradient in the surroundings of the product. On the other hand, a temperature increase can contribute to a decrease in the tendency to case hardening. The effective diffusion of water inside the meat product usually increases exponentially with temperature, as predicted by Arrhenius’s law (Mittal, 1999; Palmia et al., 1993). The higher the transport rate of water inside the product, the later case hardening will occur, or the lower its intensity, because surface water will constantly be replaced by water migration from inside the product, keeping it moist (Beserra et al., 1998a). Nevertheless, the higher the temperature, the higher the microbial risks and the greater the possibility of protein denaturation. Another possible effect of an increase in temperature is fat melting, which can contribute to a hydrophobic barrier in the product, favoring the smearing effect. There is thus a concern over the use of low-melting-point fats in the manufacture of this kind of product. Although the usual procedure in meat drying involves the use of air at low temperature, atmospheric pressure, and controlled RH, innovative procedures appear from time to time. Comaposada et al. (2004a) patented an accelerated method for drying and maturing sliced food products, particularly meat products. Basically, whole

5 Principles of Drying

35

Isoenthalpic lines (kcal/kg d.a.)

st

iG decreases when moving to the left Relative humidity curves

iG2 iG1

Isotherm lines (°C or °K)

t1

RH decreases when moving upwards t2

RH=100%

t decreases when moving downwards

X (kg w/kg d.a.)

Figure 5.6 Scheme of the Mollier diagram.

frozen pieces of meat are sliced and then submitted to vacuum drying, leading to a significant reduction in the traditional drying procedure across the whole piece (Comaposada et al., 2004a). Nathakaranakule et al. (2007) proposed the use of superheated steam-drying techniques for chicken meat. They observed that the use of superheated steam-drying followed by heat pump-drying enabled dried chicken with a lower percentage of shrinkage and a good percentage of rehydration to be obtained, compared with other drying procedures. Finally, Cárcel et al. (2012) proposed the use of low-frequency and high-intensity ultrasounds to improve the drying process, through the action of the mechanical energy of the ultrasound waves.

5.5 Drying kinetics modeling Modeling the drying behavior of meat and poultry products is a very complex task (Kottke et al., 1996). First, the phase controlling the drying process (the surrounding air, the meat product, or both) must be defined. Under real processing conditions, both the internal and the external phase control the drying process (Simal et al., 2003). The Biot number for mass transfer must be used to define under which conditions the process is accomplished. Nevertheless, it is usually assumed that the internal phase is controlling the drying process, and the diffusion equations obtained by integrating Fick’s law for diffusion (Crank, 1975) are used to model the experimental results. Water diffusion inside the food depends on many factors: temperature (Gou et al., 2004), structure (Gou et al., 2002), fat and moisture content (Kottke et al., 1996), pH (Gou et al., 2002), shrinkage (Trujillo et al., 2007), even the equation used to obtian the size and shape of the sample (Merts et al., 1998; Trujillo et al., 2007). A wide range of effective diffusion (De ) values can thus be found in the literature, from 0.9 × 10−11 to 5.3 × 10−10 m2 /s (Mittal, 1999; Motarjemi, 1988), even for the same product under the same drying conditions (Trujillo et al., 2007).

5.6 Air conditioning and circulation in meat drying As was stated in the previous sections, in addition to the temperature and the speed of the air, the air RH control is fundamental to an adequate drying process (one that is fast, safe, and involves minimal case hardening). The aim of this section is to describe the fundamentals of air conditioning in order to allow for a better understanding of the drying chambers used in the processes. All of the explanations given are supported on a psychometric chart, in this case the Mollier diagram shown schematically in Figure 5.6. The x axis indicates the absolute humidity of the air (kg water/kg dry air); the curves indicate the RH of the air, with the highest possible value corresponding to saturation (100%); the lines crossing the diagram diagonally from top-left to bottom-right correspond to isoenthalpic values (kcal/kg dry air); and the lines close to horizontal correspond to isotherms (∘ C or ∘ K). There are four main operations in air conditioning: humidifying, dehumidifying, cooling, and heating. Through a combination of some or all of these, any combination of RH and temperature in the regular range of work can be achieved. Figure 5.7 shows a basic scheme of the combination of these operations enabling the desired temperature and RH to be obtained inside the drying chamber. When working the first heater (HE1), the temperature of the air increases, through a vertical line in the Mollier diagram (X constant, iG increasing, RH decreasing) (Figure 5.8). This operation is usually accomplished in order to increase the water-retaining capacity of the air. The next step consists in an increase in air moisture (HU). The usual method of introducing water vapor into the air consists in spraying water (mechanically or through the use of ultrasound humidifiers). This method is isoenthalpic, which means that no net energy changes exist in the air, and thus the changes in the air properties occur following an isoenthalpic line. The following operation is air cooling (CO). This allows an RH equal to 100%

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Handbook of Fermented Meat and Poultry

Heating (HE1)

Humidifying (HU) Cooling (CO)

Heating (HE2)

Figure 5.7 Basic scheme for air conditioning.

st

HU HE1

2

1 HE2

CO

RH=100%

X (kg w/kg d.a.)

Figure 5.8 Scheme of changes in the air conditions throughout a conditioning process.

to be reached, obtaining a final X value by controlling the final air temperature (dehumidifying process). Finally, the air is heated (HE2) to reach the desired RH. The combination of these operations (HE1 + HU + CO ++ HE2) is required when the initial air conditions are to the left of the final air conditions in the Mollier diagram (Figure 5.8). The over-humidifying is necessary because accurate control of the X value after humidification is not possible, while temperature control of the air does not cause any problem in industry. It must be kept in mind that these are the basic principles of air conditioning. In industry, more complex situations exist because the air-recycling and air-conditioning devices vary according to

Figure 5.10 Air circulation in very high drying chambers.

the equipment supplier. The homogeneity of air conditions inside the drying chambers is very important. The regular method of circulation is to introduce air downstream through orifices placed on the walls and to suction it through holes placed in the center of the ceiling (Figure 5.9). More homogeneous drying conditions can be achieved by changing the air direction in the chamber, introducing the air into the chamber at two different points (in the case of very high chambers; Figure 5.10), or alternating the holes used to suction the air through the ceiling. Finally, most of the air in the chamber is reused, but some is renewed.

References

Figure 5.9 Normal method of air circulation inside a drying chamber.

Adams MR, Robert-Nout MJ. 2001. Fermentation and Food Safety. Dordrecht: Kluwer Academic Publishers. Aymerich MT, Garriga M, Monfort JM, Nes I, Hugas M. 2000. Bacteriocin-producing lactobacilli in Spanish-style fermented sausages: characterization of bacteriocins. Food Microbiology, 17(1), 33–45. Baker ChGJ. 1997. Industrial drying of foods. London: Blackie Academic & Professional. Barat JM, Grau R, Ibáñez JB, Fito P. 2005. Post-salting studies in Spanish cured ham manufacturing: time reduction by using brine thawing-salting. Meat Science, 69, 201–208. Barat JM, Grau R, Fito P, Chiralt A. 2006. Vacuum salting treatment for accelerating processing of dry-cured ham. In: Advanced Technologies for Meat Processing. L Nollet, F Toldra (eds), pp. 353–369. London: Marcel Dekker.

5 Principles of Drying Bertram HC, Kohler A, Böcker U, Ofstad R, Andersen HJ. 2006. Heat-induced changes in myofibrillar protein structures and myowater of two pork qualities: a combined FT-IR spectroscopy and low-field NMR relaxometry study. Journal of Agricultural and Food Chemistry, 54(5), 1740–1746. Beserra FJ, Fito P, Barat JM, Chiralt A, Martínez-Monzó J. 1998a. Drying kinetics of Spanish Salchichón. Proceedings of the 44th International Congress of Meat Science and Technology, Vol. II, pp. 872–873, Barcelona, Spain. Beserra FJ, Fito P, Chiralt A, Barat JM, Martínez-Monzó J. 1998b. Influence of ripening conditions on the pH, colour and texture development of Spanish Salchichón. Proceedings of the 44th International Congress of Meat Science and Technology, Vol. II, pp. 870–871, Barcelona, Spain. Bimbenet JJ, Lebert A. 1990. Some practical questions and remarks about drying. In: Engineering and Food Preservation Processes and Related Techniques, Vol. 2. WEL Spiess, H Schubert (eds). London: Elsevier Applied Science. Cárcel JA, García-Pérez JV, Benedito J, Mulet A. 2012. Food process innovation through new technologies: use of ultrasound. Journal of Food Engineering, 110, 200–207. Careaga MO, Fernández E, Dorantes L, Mota L, Jaramillo ME, Hernandez-Sanchez H. 2003. Antibacterial activity of capsicum extract against Salmonella typhimurium and Pseudomonas aeruginosa inoculated in raw beef meat. International Journal of Food Microbiology, 83(3), 331–335. Cava-López R, Andrés-Nieto A. 2001. El Ahumado de los Productos Cárnicos. In: Enciclopedia de la Carne y de los Productos Cárnicos, Vol. II. M Bejarano (ed.), pp. 983–993. Plasencia, Cáceres: Martín & Macías. Coffey A, Ryan M, Ross RP, Hill C, Arendt E, Schwarz G. 1998. Use of a broad-host-range bacteriocin-producing Lactococcus lactis transconjugant as an alternative starter for salami manufacture. International Journal of Food Microbiology, 43(3), 231–235. Comaposada J, Arnau J, Gou P, Monfort JM. 2004a. Accelerated method for drying and maturing sliced food products. Patent WO/2005/092109. Comaposada J, Gou P, Muñoz I, Arnau J. 2004b. Caracterización y análisis de distribución de temperaturas, humedades relativas y velocidades de aire en un secadero industrial de embutidos. Eurocarne, 1–13. Crank J. 1975. The Mathematics of Diffusion. London: Oxford University Press. Doe P, Sikorski Z, Haard N, Olley J, Pan BS. 1998. Basic principles. In: Fish Drying and Smoking: Production and Quality. PE Doe (ed.), pp. 13–45. Lancaster, PA: Technomic. García-Esteban M, Ansorena D, Astiasaran I. 2004. Comparison of modified atmosphere packaging and vacuum packaging for long period storage of dry-cured ham: effects on colour, texture and microbiological quality. Meat Science, 67, 57–63. Garriga M, Grèbol N, Aymerich MT, Monfort JM, Hugas M. 2004. Microbial inactivation after high-pressure processing at 600 MPa in commercial meat products over its shelf life. Innovative Food Science and Emerging Technologies, 5, 451–457. Gou PJ, Comaposada J, Arnau J. 2002. Meat pH and meat fibre direction effects on moisture diffusivity in salted ham muscles dried at 5 ∘ C. Meat Science, 61(1), 25–31. Gou P, Comaposada J, Arnau J. 2004. Moisture diffusivity in the lean tissue of dry-cured ham at different process times. Meat Science, 67(2), 203–209. Gou P, Comaposada J, Arnau J, Pakowski Z. 2005. On-line determination of water activity at the lean surface of meat products during drying and its relationship with the crusting development. Drying Technology, 23(8), 1641–1652. Gould WA. 1920. Fundamentals of Food Processing and Technology. Lutherville Timonium, MD: CTI Publications. Hammes WP, Hertel C. 1998. New developments in meat starter cultures. Meat Science, 49(Suppl. 1), S125–S138.

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Heldman DR, Hartel RW. 1997. Principles of Food Processing. New York: Chapman & Hall. Hoz L, Arrigo MD, Cambero I, Ordóñez JA. 2004. Development of an n-3 fatty acid and a-tocopherol enriched dry fermented sausage. Meat Science, 67, 485–495. IFT/FDA. 2003. Factors that influence microbial growth. Comprehensive Reviews in Food Science and Food Safety, 2, 21–32. Kottke V, Damm H, Fischer A, Leutz U. 1996. Engineering aspects in fermentation of meat products. Meat Science, 43(1), 243–255. Leistner L. 1995. Principles and applications of hurdle technology. In: New Methods of Food Preservation. GW Gould (ed.), pp. 1–21. London: Blackie Academic & Professional. Lücke FK. 1999. Utilization of microbes to process and to preserve meat. Proceedings of the 45th International Congress of Meat Science and Technology, pp. 538–547. Merts I, Lovatt SJ, Lawson CR. 1998. Diffusivity of moisture in whole muscle meat measured by a drying curve method. IIR Proceedings Series Refrigeration Science and Technology, Sofia, Bulgaria, pp. 473–479. Mittal GS. 1999. Mass diffusivity of meat food products. Food Review International, 15(1), 19–66. Motarjemi Y. 1988. A study of some physical properties of water in foodstuffs: water activity, water binding and water diffusivity in minced meat products. PhD thesis, Lund University, Lund, Sweden. Mujumdar AS. 1995. Handbook of Industrial Drying, Vol. 1. New York: Marcel Dekker. Muthukumarasamy P, Holley RA. 2006. Microbiological and sensory quality of dry fermented sausages containing alginate-microencapsulated Lactobacillus reuteri. International Journal of Food Microbiology, 111, 164–169. Nathakaranakule A, Kraiwanichkul W, Soponronnarit S. 2007. Comparative study of different combined superheated-steam drying techniques for chicken meat. Journal of Food Engineering, 80, 1023–1030. Palmia F, Pecoraro M, Ferri S. 1993. Essiccazione di prodotti carnei: calcolo del coefficiente di diffusione effettivo (De ) dell’acqua in fette di lombo suino. Industria Conserve, 68, 238–242. Rubio B, Martínez B, González-Fernández C, García-Cachán MD, Rovira J, Jaime I. 2006a. Influence of storage period and packaging method on sliced dry cured beef “Cecina de Leon”: effects on microbiological, physicochemical and sensory quality. Meat Science, 74, 710–717. Rubio B, Martínez B, González-Fernández C, García-Cachán MD, Rovira J, Jaime I. 2006b. Development of an n-3 fatty acid and a-tocopherol enriched dry fermented sausage. Meat Science, 67, 485–495. Ruiz-Ramírez J, Serra X, Arnau J, Gou P. 2005. Profiles of water content, water activity and texture in crusted dry-cured loin and in non-crusted dry-cured loin. Meat Science, 69(3), 519–525. Serra X, Ruiz-Ramírez J, Arnau J, Gou P. 2005. Texture parameters of dry-cured ham m. Biceps femoris samples dried at different levels as a function of water activity and water content. Meat Science, 69, 249–254. Shelef LA. 1983. Antimicrobial effects of spices. Journal of Food Safety, 6, 29–44. Simal S, Femenia A, Garcia-Pascual P, Rosselló C. 2003. Simulation of the drying curves of a meat-based product: effect of the external resistance to mass transfer. Journal of Food Engineering, 58(2), 193–199. Singh RRB, Rao KH, Anjaneyulu ASR, Patil GR. 2001. Moisture sorption properties of smoked chicken sausages from spent hen meat. Food Research International, 34, 143–148. Smith HJ, Messier S, Tittiger F. 1989. Destruction of Trichinella spiralis spiralis during the preparation of the “dry cured” pork products proscuitto, proscuittini and Genoa salami. Canadian Journal of Veterinary Research, 53, 80–83. Soriano A, Cruz B, Gómez L, Mariscal, C García-Ruiz A. 2006. Proteolysis, physicochemical characteristics and free fatty acid composition of dry

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sausages made with deer (Cervus elaphus) or wild boar (Sus scrofa) meat: a preliminary study. Food Chemistry, 96, 173–184. Stabursvik E, Martens H. 1980. Thermal denaturation of proteins in post rigor muscle tissue as studied by differential scanning calorimetry. Journal of the Science of Food and Agriculture, 31, 1034–1042. Toldrá F. 2002. Dry-Cured Meat Products. Trumbull, CT: Food & Nutrition Press. Trujillo FJ, Wiangkaew C, Pham QT. 2007. Drying modeling and water diffusivity in beef meat. Journal of Food Engineering, 78(1), 74–85.

Valencia I, Ansorena D, Astiasarán I. 2006. Stability of linseed oil and antioxidants containing dry fermented sausages: a study of the lipid fraction during different storage conditions. Meat Science, 73, 269–277. Yean YS, Pruthiarenun R, Doe P, Motohiro T, Gopakumar K. 1998. Dried and smoked fish products. In: Fish Drying and Smoking: Production and Quality. PE Doe (ed.), pp. 47–87. Lancaster, PA: Technomic. Zaika LL. 1988. Spices and herbs: their antimicrobial activity and its determination. Journal of Food Safety, 9, 97–118.

6

Principles of Smoking Zdzisław E. Sikorski and Izabela Sinkiewicz ´ Department of Food Chemistry, Technology, and Biotechnology, Gdansk ´ University of Technology, Gdansk, Poland

6.1 Introduction Treatment of a large variety of foods with wood smoke has been practiced for centuries—predominantly meats, poultry, and fish, but also scallops, cheeses, prunes, paprika, and the malt used to produce whiskey and some sorts of beer. The process usually includes salting and partial drying; it may also be coupled with heating. The aim is to increase the shelf life of the products, prevent food poisoning, and add a desirable smoky flavor. Smoking is applied at both an industrial scale in food plants and in traditional artisan processing in simple kilns. With the advent of canning, freezing, and the refrigeration chain, the preservative effect of smoking has gradually lost its importance. The process parameters required to obtain a very long shelf life through smoking are very severe and may decrease the nutritional value of a product and increase the health risks for the consumer.

6.2 Wood-smoke composition Smoke develops from the charring of wood: beech, oak, alder, hickory, or maple, as well as fruit trees. Pinewood is used only seldom. To produce the desirable flavor that is characteristic of some products, juniper berries or pinecones are added to the smoldering material. The wood usually takes the form of shavings or sawdust. Today, these are available commercially in different assortments of standardized mesh size and moistness. In old-type kilns and friction-type generators, wood logs are also used. The thermal decomposition of the woody material, followed by oxidation, generates hundreds of solid, liquid, and gaseous compounds, differing in boiling point, solubility, chemical properties, and the role they play in food smoking. These are mainly H2 O, CO, CO2 , alcohols, carbonyl compounds, carboxylic acids, esters, hydrocarbons, nitrogen oxides, and phenols. The yield of the various components depends on the species of wood and the smoldering parameters. Mixed with air, they form a complex aerosol. The mass proportion of the dispersing and dispersed phases of the aerosol depends on the chemical composition of the constituents and on temperature: heating increases the concentration of components in the gaseous phase, while cooling causes many compounds to

condensate and so move in the form of tiny solid particles or liquid droplets to the dispersed phase. The phenolic fraction, about 240 items, contains mainly guaiacol and its derivatives, phenol, 2,5-dimethylphenol, cresols, syringol and its derivatives, pyrocatechins, resorcinol, pyrogallol, hydroquinone, and hydroxy-dimetoxyphenylo-ketones. The composition of the phenolic fraction depends on the temperature of smoke generation. Increasing the temperature decreases the content of syringol and 4-methylguaiacol and the percentage of trans-isoeugenol. The highest yield of smoke phenols occurs in the temperature range 480–520 ∘ C. The smoke aldehydes and ketones are also numerous. Formaldehyde is generated by the oxidation of methanol, one of the main products of the dry distillation of wood. The group of carbonyl compounds includes inter alia acetaldehyde, benzaldehyde, acetone, and furanone. The acid fraction contains mainly acetic acid, other components being various short-chain carboxylic and ketocarboxylic acids. Among the alcohols are a variety of low-molecular-weight aliphatic compounds. Several components have been identified also in the ester fraction. The group of hydrocarbons comprises various aliphatic compounds and polycyclic aromatic hydrocarbons (PAHs). Wood smoke contains about 60 identified PAHs, differing in number of aromatic rings and structure, as well as in physical and biological properties. Among them are the following 16 potentially mutagenic and/or carcinogenic ones: cyclopenta[cd]pyrene, benzo[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[j]fluoranthene, benzo[k] fluoranthene, benzo[a]pyrene (BaP), benzo[ghi]perylene, dibenzo [ah]anthracene, dibenzo[ae]pyrene, dibenzo[ah]pyrene, dibenzo [ai]pyrene, dibenzo[al]pyrene, indeno[1,2,3-cd]pyrene, 5-methylchrysene, and benzo[c]fluorene. The structure of these compounds determines their biological activity, because in the living organism they are activated on different routes, which are catalyzed by various enzymes. The concentration of PAHs in wood smoke depends mainly on the temperature of the smoldering wood and on the access of air. Increasing the smoke-generation temperature leads to a larger proportion of the high-molecular-weight compounds in the total PAHs. The content of PAHs in the smoke can be minimized by keeping the glowing temperature below 400 ∘ C and removing the tar. Wood smoke can be condensed and purified, yielding various preparations. These are used for smokeless smoking of meats. The

Handbook of Fermented Meat and Poultry, Second Edition. Edited by Fidel Toldrá. © 2015 John Wiley & Sons, Ltd. Published 2015 by John Wiley & Sons, Ltd.

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Handbook of Fermented Meat and Poultry

concentration of PAHs in such preparations can be effectively controlled. According to EU Directive 2065/2003, the BaP content in smoke preparations must not exceed 10 ng/g (European Parliament, 2003).

6.3 The preserving effect Smoking of foods can be regarded as “hurdle technology” (Figure 6.1). Smoked products are not sterile. The preserving effect results from the consecutive or simultaneous action of several of the following factors: thermal inactivation of the spoilage microflora, water activity, pH, antibacterial activity of additives used prior to smoking, concentration of antimicrobial and antioxidant smoke components in the product, barrier properties of the packing, and storage temperature. Therefore, the high-quality life and the practical storage time of various smoked foods extends from a few days in refrigeration conditions to several months at room temperature, depending on the kind, initial freshness, microbial contamination, and form of the raw material, on the parameters of salting and curing, on loss of water due to dripping or drying, temperature, duration, and smoke density in the smokehouse, and on the conditions of packaging and storage of the product. Numerous components of wood smoke have antimicrobial activity in concentrations similar to those found in smoked meats. Among the most active are various phenols, especially guaiacol and its derivatives, cresol, pyrocatechols, and pyrogallol. The contents and distributions of the phenols and their derivatives in smoked meats are related to their solubility in the lipid and water phases of the products, as well as to the smoking conditions. Mini-salamis in sheep casings, 18–20 mm in diameter, smoked for 30 minutes at 22 ∘ C with smoldering smoke from beechwood chips, contain

from 30 to 72 μg/g of the sum of guaiacol, 4-methylguaiacol, syringol, eugenol, and trans-isoeugenol (Hitzel et al., 2012), while hot-smoked frankfurter-type sausages contain 19.6–57.6 μg/g, depending on the process parameters (P˝ohlmann et al., 2012). Compounds with an additional aldehyde group in their structure are more effective antimicrobials than phenols. The sensitivity of different species and strains of microorganism towards various phenols may significantly differ in broth and in smoked meat products. The growth inhibitory concentration of some smoke phenols in broth towards Listeria monocytogenes is in the range of 10–100 μg/g. However, as yet it is not possible to predict exactly the concentration of total smoke phenols that is necessary for an inhibitory effect on, for example, L. monocytogenes or Clostridium botulinum in foods. Cold smoking may decrease the population of L. monocytogenes on the surface of the products, but might also lead to proliferation of these bacteria in meats cured with contaminated brine. The growth of L. monocytogenes has been shown in various ready-to-eat smoked products. Smoke carbonyl compounds, especially formaldehyde, are also known to retard the proliferation of microorganisms. Smoked meats may contain up to 125 μg/g formaldehyde. Most sensitive are the vegetative forms of bacteria; molds and yeasts are more resistant. Many molds were isolated from fully ripened, lightly smoked Norwegian dry-cured meats, and the predominant species were found to belong to the genus Penicillium (Asefa et al., 2009). Generally, smoke components alone cannot protect lightly smoked foods from spoilage and microbial hazards for long. At the concentrations found in foods, the smoke constituents do not decrease the population of various pathogenic microorganisms by several log cycles, or efficiently restrain their growth. A significant antilisterial effect can be achieved by adding potassium lactate and sodium diacetate to the sausage formulation and by 2 minutes’ immersion

1

2 3

Log number of bacteria / g

4 5 6 7 8 9

10 11 Time of storage

Figure 6.1 Effect of preservative treatments on the growth of bacteria in foods: (1) untreated food, room temperature; (2) refrigeration; (3) chemical preservation and refrigeration; (4) chemical preservation, modified atmosphere, and refrigeration; (5) drying or salting, room temperature; (6) marination or lactic acid fermentation, room temperature; (7) drying or salting and refrigeration; (8) freezing; (9) heat pasteurization, room temperature; (10) heat pasteurization and chemical preservation, room temperature; (11) heat pasteurization and refrigeration.

6 . O

OH .

R6

R6

R2

R4

O

R2 R6

R2 .

R4 R6

41

O .

LOOH +

LOO +

. LOO +

O R2 R6

Principles of Smoking

R4

R4

O R2

R6

R2

. R4

R4

OOL

Figure 6.2 Mode of action of a phenolic antioxidant.

of the smoked sausages in various antimicrobial solutions. Spraying frankfurters with liquid smoke of pH 4.25–4.85, containing in 1 cm3 0.3–0.8 mg of phenols, decreased the surface population of L. monocytogenes during storage at 4 ∘ C by several log cycles (Martin et al., 2010). In a particular smoked product type, the effect on the bacterial population depends on all factors involved in the hurdle technology and on the implementation of the food safety management system. Smoking also prolongs the shelf life of foods by decreasing the rate of lipid oxidation, mainly due to the antioxidant activity of various phenols. The phenolic antioxidants are capable of inactivating different free radicals present in the products by donating the hydrogen atom of the OH group and thus breaking the chain reaction of lipid autoxidation (Figure 6.2). A phenolic radical created by abstraction of the hydrogen atom has a lower reactivity than other free radicals, as a result of the resonance delocalization of the radical function in the aromatic structure. The activity of the phenol antioxidant increases with decreasing binding energy of the hydrogen atom in the OH group and decreasing energy of the created phenolic radical. Both of these characteristics depend on the structure of the compound, which explains why various smoke phenols differ in antioxidant effect. The activity of several smoke components exceeds that of the known food additives buthylhydroxyanisole (BHA) and buthylhydroxytoluene (BHT). The most effective are resorcinol, pyrogallol, 4-methylguaiacol, 4-vinylguaiacol, and trans-4-propenylsyringol. The protective action of smoking depends too on the presence in food of various compounds that decrease the activity of the antioxidants or act synergistically on the factors influencing the rate of formation of reactive oxygen species (ROS), as well as on the distribution of lipids in the product. Thus, complete arrest of lipid changes is not possible, and various compounds generated due to thee oxidation of polyenoic fatty acids occur in smoked meat, among them minute amounts of the cytotoxic aldehyde 4-hydroxy-2-nonenal.

6.4 The flavoring effect 6.4.1 Introduction The sensory properties of smoked foods depend on the type of product, its initial quality, the preparation of the raw materials prior to smoking, loss of moisture and thermal changes during processing, and the concentrations of various smoke components on the surface

and in the deeper layers of the product. The color, flavor, and taste typical of smoked meats and fish are formed by the smoke compounds, while the texture, juiciness, and saltiness result from the properties of the raw material and the processing parameters.

6.4.2 Color The color of the surface of smoked foods is a blend of the pigmentation of the raw material and that resulting from the action of the smoke components. The tint added by smoking extends from light lemon to dark brown, depending mainly on the kind of smoldering wood and the time/temperature regime of the process. It is especially visible on the carcasses of poultry and the originally whitish or silvery belly parts of fish, while on many sausages and other meat products a red coloration predominates. The color added by smoking is a result of the deposited colored smoke components, their changes during heating and storage, and their interactions with the surface material of the product. The chemical changes involved comprise mainly polymerization of phenols and the Maillard reaction; their rate increases with temperature. Thus, raising the smoke temperature promotes darker colorization of the products. Most important is the amount of deposited smoke components. Heavily smoked goods—that is, those kept in a dense smoke for a long time—turn very dark brown. This color can also develop on surfaces containing no components capable of interacting with the reactive smoke compounds. The tint is also affected by the characteristics of the sawdust taken for smoke generation; using beech, maple, ash, sycamore, or lime tree shavings favors a golden-yellow color, while oak, nut, and alder smokes cause yellow-brownish coloration, and meats treated with smoke from coniferous wood have a dark coloration. Consumer preferences regarding the color of various smoked meat products are not equal in different regions.

6.4.3 Flavor and taste The smoky flavor is created mainly by the smoke components deposited on the product, predominantly the phenols. The compounds that contribute to the formation of the desirable flavor are mainly syringol, 4-methylsyringol, 4-allylsyringol, guaiacol, 4-methylguaiacol, and trans-isoeugenol. Carbonyl compounds, furans, and other smoke constituents play a role as well, although the exact proportions of the concentrations of different smoke components in the creation of various flavor notes have not been disclosed.

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Handbook of Fermented Meat and Poultry

Smoke phenols, aldehydes, and acids interact with different food components. This may affect the sensory qualities of the products.

6.5 Benefits and risks 6.5.1 Introduction The intended, desirable effects of smoking comprise first the formation of the typical sensory properties of the products—attractive features are added to smoked foods, which are highly valued by many consumers—and second, the prolonged storage life of the product, brought about by the prevention of the growth of some microorganisms, including pathogens, and by the delay of lipid oxidation. Smoked foods may contain microbial toxins carried through from the raw material or generated by microflora that survive the processing and are active in the product during storage. They may also harbor excessively large populations of pathogenic microorganisms. The hazards that can be caused by pathogenic microflora depend on the initial contamination of the raw materials, on the lethal and growth-inhibitory effects of the processing procedure, and on the handling and storage parameters of the products. Further risks are caused by certain smoke components deposited on the meats and the effects of their interactions with the product constituents. Most smoke compounds would not be allowed by law to be added to foods in pure form; however, as their toxicity and concentration in these products are very low, smoking is generally regarded as safe (GRAS), in accordance with the common law principle De minimis non curat lex.

6.5.2 PAHs The smoke components that are hazardous to consumer health and whose content in smoked foods is limited by law are the PAHs. The mutagenic/carcinogenic activities of ingested individual PAHs, as well as their concentrations, are different in various smoked foods. Thus, it is very difficult to predict the degree of health hazard caused by these compounds in smoked foods. Various PAHs have been proposed as indicators of carcinogenicity. Until recently, BaP was regarded as such, since it is a very potent mutagenic and carcinogenic compound. This indicator is, however, not generally accepted anymore, as some smoked goods contain a large number of other highly carcinogenic PAHs and no BaP. On the other hand, the content of BaP in many different smoked meat products has been found to be highly correlated with that of most other carcinogenic PAHs (Lorenzo et al., 2011). According to a statement by the European Food Safety Authority (2008), a more adequate index of the carcinogenicity of smoked foods is the sum of the concentration of BaP, benzo(a)anthracene, benzo(b)fluoranthene, and chrysene (PAH4) (Figure 6.3), or else the concentration of eight carcinogenic PAHs (PAH8): the PAH4 plus benzo[k]fluoranthene, benzo [g,h,i]perylene, dibenzo[a,h]anthracene, and indeno[1,2,3-cd] pirene. However, because most earlier published data on PAHs in smoked foods regarded the content of BaP, Commission Regulation (EU) No. 835/2011 (European Commission, 2011) decided to keep the maximum level of this indicator in smoked meat and meat products at 5 ng/g until August 2014, and at 2 ng/g afterwards. Additionally, an upper limit of 30 ng/g for PAH4 has been introduced until August 2014, and 12 ng/g afterwards.

benzo(a)pyrene

benzo(b)fluoranthene

benzo(a)anthracene

chrysene

Figure 6.3 The four polycyclic aromatic hydrocarbons (PAH4) treated as an index of the carcinogenicity of smoked foods.

The content of PAHs in smoked meat products available on the market is usually well below the maximum level set by the EU. The limits of quantification of individual PAHs achievable by contemporary analytical procedures range from 0.009 to 0.030 ng/g (Jira et al., 2008). Various assortments of smoked meats usually contain no more than 1 ng BaP/g, although very heavily smoked products may reach up to 50 ng BaP/g. Meat products manufactured by traditional Swedish “sauna” smoking involving direct exposure to hot smoke generated by a flaming log fire were found to contain 6.6–36.9 ng BaP/g (Wretling et al., 2010). Market samples of smoked meats in Kuwait contained 0.97–1.20 ng BaP/g, 3.26–7.45 ng PAH8/g, and 82.9–110.0 ng total PAHs/g (Alomirah et al., 2011). According to different published data on about 600 smoked meat products, the contents of BaP, PAH4, and PAH8 were about 0.20, 1.5, and 1.8 ng/g, respectively. The concentration of 16 PAHs in 22 samples of smoked ham ranged from below 0.01 to 19 ng/g, with the median for BaP being below 0.15 ng/g (Jira et al., 2008). In the raw-cured Spanish pork sausages androlla and botillo, smoked 8–10 and 7–15 days, respectively, in traditional kilns and ripened for several months, the mean contents of the 16 potentially mutagenic and/or carcinogenic PAHs were 36.5 and 29.4 ng/g, respectively, in which the BaP content ranged from 15 to 17% (Lorenzo et al., 2010). The accumulation of PAHs in different smoked meat products is related very significantly to the parameters of smoking and the kind of wood used for smoke generation. Assortments of sausages made of various raw materials, although having the same mass to surface ratio and being smoked in identical conditions, contain different amounts of PAHs (Roseiro et al., 2012). In traditionally smoked sausages, the PAHs content depends even on the location of the product in the kiln, which affects the temperature and flow rate of the smoke. Meat products treated with smoke made from the wood of apple tree and alder contained about 10 times less total PAHs than samples smoked in the same conditions with spruce smoke (Stumpe-V̄ıksna et al., 2008). Generally, the PAHs contamination of products smoked in strictly controlled conditions in modern smokehouses with external smoke generators is significantly lower than that of meats processed in old-type kilns with smoldering chips or burning wood logs directly under the hanging rows of

6

sausages. The inner parts of the products are less contaminated than the surface layers, although during storage this difference gradually diminishes. The skin is an effective barrier for PAHs; this applies for various smoked fish, especially eel, and has been shown to hold for bacon smoked with skin versus that without (Djinovic et al., 2008). The concentration of PAHs in smoked products changes during storage. Being hydrophobic, they accumulate in fatty tissues at a rate controlled by the parameters of diffusion. They may also be absorbed by low-density polyethylene packaging films and there partially destroyed by UV radiation (Chen & Chen, 2005; Šimko, 2005). The photochemical changes induced by UV involve oxidation of peripheral carbons, leading to aromatic alcohols, ketones, and ethers.

6.5.3 Other hazardous compounds The reactions of various smoke constituents with the components of foods may result in the formation of different groups of hazardous compounds. Smoking, as applied in the manufacture of the smoked dry-cured ham prosciutto di Sauris (2–3 days at 20 ∘ C), has been found to have only a very limited effect on protein hydrolysis and the accumulation of biogenic amines in the meat (Martuscelli et al., 2009). Several heat-treated foods may contain nitropolycyclic aromatic hydrocarbons in concentrations of up to about 30 ng/g. In smoked sausages, the contents of 1-nitropyrene, 2-nitronaphtalene, and 2-nitrofluorene have been found to be in the range of about 4–20 ng/g N-nitroso compounds, most of which are carcinogenic in laboratory animals, may be formed in smoked foods by the reaction of smoke aldehydes with cysteamine and cysteine, yielding various thiazolidine precursors that can be easily nitrosated. In various smoked meat and poultry products, the contents of N-nitroso compounds may reach up to several hundreds of ng/g. Heterocyclic aromatic amines, known to be generated in pyrolytic reactions of amino acids and proteins and in non-enzymatic browning, are present in very heavy smoked goods in amounts lower than 1 ng/g. In various smoked foods, β-carboline alkaloids are also found. These may be formed in the reaction of L-tryptophan with formaldehyde or acetaldehyde (see Figure 6.4). The concentration of these compounds increases with temperature and duration of smoking, and depends on the accumulation of formaldehyde with the smoke. In sausages, 1,2,3,4-tetrahydroβ-carboline-3-carboxylic acid (THCA) is found in concentrations of 0.01–14.80 μg/g. The outer surfaces of smoked products may contain up to eight times more THCA than the core (Papavergou & Herraiz, 2003). O

N H

NH2

Tryptophan

Figure 6.4 Formation of β-carboline alkaloids.

H

43

6.6 Food engineering approach 6.6.1 Mass and heat transfer The aim of meat smoking is to achieve a desirable product quality through the action of the smoke and heat and the loss of moisture. The smoke constituents settle on the meat, driven by gravitational and centrifugal forces, and are absorbed in the thin film of water on the surface. The rate of deposition of various compounds depends on whether they are in the dispersing or dispersed phase of the aerosol at the given temperature and on the condition of the surface layer (Miler & Sikorski, 1990). Therefore, the temperature, humidity, and flow rate of the smoke significantly affect the efficiency of the sorption phenomena. These factors control the absorption of smoke components in conventional smoking, as well as in smokehouses supplied with dispersed, atomized smoke preparations. If the preparations are used in the form of dips, the process is governed by the laws of diffusion. In electrostatic smoking (Figure 6.5), the decisive factor is the electrostatic force, which drives the electrically charged smoke particles towards the product and creates an electric wind to carry the uncharged components of the aerosol in the same direction.

4

‒30 kV

3

5

2

6

1

Figure 6.5 The principle of electrostatic smoking: (1) smoke inlet; (2) smoked sausage; (3) metallic, grounded conveyer chain; (4) smoke outlet; (5) insulator; (6) ionizing electrode. Source: Courtesy of Łukasz Wi´sniewski.

O

O

OH

Principles of Smoking

H

OH

H+

N H

NH

1,2,3,4-Tetrahydro-β-carboline-3-carboxylic acid

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Handbook of Fermented Meat and Poultry

Figure 6.7 Modern smokehouse. Source: Courtesy of Łukasz Wi´sniewski.

Figure 6.6 Wi´sniewski.

Traditional smoking kiln. Source: Courtesy of Łukasz

The temperature, humidity, and flow rate of smoke/air also influence the rate of loss of moisture from the smoked meats, as well as the heat transfer by convection and by condensation of water vapor on the cool surface of the product in the early stage of smoking.

6.6.2 Equipment In artisanal manufacturing of smoked foods, the sensory, nutritional, food-safety, and economic requirements are fulfilled by a trained craftsperson, who knows by experience how to process a given raw material using the available wood and equipment at the prevailing atmospheric conditions. Artisan smoking usually takes place in kilns, in which logs of wood burning on the floor and smoldering shavings or sawdust supply the necessary heat and smoke (Figure 6.6). The meat to be smoked is hung on racks at different heights above the fireplace. The conditions prevailing in various locations in the kiln differ significantly; therefore, it may be necessary to reverse the racks of sausages during the process. The temperature, density, and humidity of the smoke are controlled to some degree by the operator, by way of the proper use of the moist or dry woody material and by opening and closing the vent and doors. In order to produce high-quality smoked meats at commercial scale, contemporary requirements regarding the standard of the raw material, precisely defined and strictly applied processing parameters, rational equipment design, and proper organization of the manufacturing line should be observed. Furthermore, procedures eliminating health risks should be introduced, such as the hazard analysis and critical control points (HACCP) system. In modern smokehouses containing production lines, food engineering principles are applied to implement rational parameters of mass and heat transfer and to achieve organizational and economic goals.

Wood smoke is produced in outside generators, often filtered to separate the tar and soot, and directed into the smokehouse by ducts. Mostly smoldering-type units are used, in which the woody material is fed automatically on an electrically heated plate or grate. The temperature in the smoldering pile of sawdust can be kept at a level of 400–600 ∘ C by changing the flow rate of the air and the humidity of the woody material. Less common are various types of machine in which the smoke develops due to heat generated as a result of friction from a wood log pressed against a rotating metal ring or disk. By adjusting the pressure exerted on the log or the rotation rate of the disk, the temperature at the friction interface can be controlled; it is usually kept at about 400 ∘ C. An asset of this type of generator is that smoke develops immediately after the drive engine is switched. They are noisy, however. Several other types of machine can produce smoke at relatively low temperature. In one such unit, the smoke is developed by treating the woody material with overheated steam at about 250–390 ∘ C. Modern smokehouses are usually built in the form of kilns, tunnels, or towers (Figure 6.7). They work either periodically or continuously. The smoke is distributed evenly and circulated at controlled velocity by the action of fans and shutters. Smokehouses used to treat meats with smoke preparations are additionally equipped with nozzles or evaporating heated plates to turn the liquid preparation into an aerosol. The necessary heat is supplied by steam, gas, or electricity. The smoke temperature, density, and humidity and the smoking time are adjusted according to a program set for the particular product to be processed. In the manufacture of many types of smoked sausage, the smoking phase is followed by a period of cooking under a hot-water shower or by steam. The sausages to be smoked are hung on rods and transported into the smokehouse on trolleys, moving either on the floor or on an overhead track. In tower smokehouses, the goods are moved vertically on a chain transporter. The spent smoke leaving the smokehouse carries many atmospheric pollutants and should be cleaned. This can be done by

6

different kinds of filter or afterburner. To avoid accumulation of tars, which contain more PAHs than the smoke, and to prevent the outbreak of fire, many smokehouses have automatic cleaning systems.

6.7 Smoking procedures A number of smoking procedures have been developed in the last several centuries, suitable for treating various commodities. They differ in the mode of preparation of the raw material and in the parameters of treatment in the smokehouse—mainly smoke humidity and temperature, as well as the duration of the process. Smoking usually constitutes one of a chain of several unit operations and unit processes in the manufacture of a meat product. Depending on the intended characteristics of the product, a suitable raw material and pretreatment are selected, cold, warm, or hot smoking is applied, and different methods of heating are used (e.g., warm air, steam cooking, or cooking in water). Cold smoking, at a temperature of 12–25 ∘ C, lasts from a few hours to several days. It is typical in the manufacture of raw fermented sausages made of cured meat, some assortments produced from variety meats, and pork belly. The parameters of fermented sausage smoking should promote the proliferation of lactic acid bacteria (LAB), ensure the predetermined loss of moisture, and lead to specific, rheological properties in the product. Warm smoking, at 25–45 ∘ C (i.e., in conditions under which the fats in the batter change their consistency but no protein denaturation occurs), usually lasts up to a few hours. It is normal in the manufacture of baked or scalded sausages, pork back fat, and hams. Hot smoking is carried out at 45–90 ∘ C. Depending on the assortment of sausage, it may be applied at several stages of the manufacturing process, and it can last from a few hours up to 12. It leads to the development of smoky sensory characteristics, thermal denaturation of proteins, and a predetermined yield of product.

References Alomirah H, Al-Zenki S, Al-Hooti S, Zaghloul S, Sawaya W, Ahmed N, Kannan K. 2011. Concentrations and dietary exposure to polycyclic aromatic hydrocarbons (PAHs) from grilled and smoked foods. Food Control, 22(11), 2028–2035. Asefa DT, Gjerde RO, Sidhu MS, Langsrud S, Kure CF, Nesbakken T, Skaar I. 2009. Moulds contaminants on Norwegian dry-cured meat products. International Journal of Food Microbiology, 128(3), 435–439. Djinovic J, Popovic A, Jira W. 2008. Polycyclic aromatic hydrocarbons (PAHs) in different types of smoked meat products from Serbia. Meat Science, 60(2), 449–456. European Commission. 2011. Commission Regulation (EU) No 835/2011 of 19 August 2011 amending Regulation (EC) No 1881/2006 as regards maximum levels for polycyclic aromatic hydrocarbons in foodstuffs. Official Journal of the European Union, 20, 8, L215/6-L215/8.

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European Food Safety Authority. 2008. Polycyclic aromatic hydrocarbons in food: scientific opinion of the panel on contaminants in the food chain. EFSA Journal, 724, 1–114. European Parliament. 2003. Parliament and Council Regulation (EC) No. 2065/2003 of 10 November on smoke flavourings used or intended for use in or on food. Official Journal of the European Union, L 309, 26/11/2003/1-8. Hitzel A, Pöhlmann M, Schwägele F, Speer K, Jira W. 2012. Polycyclic aromatic hydrocarbons (PAH) and phenolic substances in cold smoked sausages depending on smoking conditions using smoldering smoke. Journal of Food Research, 1(2). Chen J, Chen S. 2005. Removal of polycyclic aromatic hydrocarbons by low density polyethylene from liquid model and roasted meat. Food Chemistry, 90, 461–469. Jira W, Ziegenhals K, Speer K. 2008. A GC/MS method for the determination of 16 European priority polycyclic aromatic hydrocarbons in smoked meat products and edible oils. Food Additives and Contaminants, 25(6), 704–713. Lorenzo JM, Purriños L, Fontán MC, Franco D. 2010. Polycyclic aromatic hydrocarbons (PAHs) in two Spanish traditional smoked sausage varieties: “Androlla” and “Botillo.” Meat Science, 86(3), 660–664. Lorenzo JM, Purriños L, Bermudez R, Cobas N, Figueiredo M, García Fontán. 2011. Polycyclic aromatic hydrocarbons (PAHs) in two Spanish traditional smoked sausage varieties: “Chorizo gallego” and “Chorizo de cebolla.” Meat Science, 89(1), 105–109. Martin EM, O’Bryan CA, Lary RY Jr, Griffis CL, Vaughn KL, Marcy JA, Ricke SC, Crandall PG. 2010. Spray application of liquid smoke to reduce or eliminate Listeria monocytogenes surface inoculated on frankfurters. Meat Science, 85(4), 640–644. Martuscelli M, Pittia P, Casamassima LM, Manetta AC, Lupieri L, Neri L. 2009. Effect of intensity of smoking treatment on the free amino acids and biogenic amines occurrence in dry cured ham. Food Chemistry, 116(4), 955–962. Miler KMB, Sikorski ZE. 1990. Smoking. In: Seafood: Resources, Nutritional Composition, and Preservation. ZE Sikorski (ed.), pp. 163–180. Boca Raton, FL: CRC Press. Papavergou E, Herraiz T. 2003. Identification and occurrence of 1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid: the main β-carboline alkaloid in smoked foods. Food Research International, 36(8), 843–848. Pohlmann M, Hitzel A, Schwagele F, Speer K, Jira W. 2012. Contents of polycyclic aromatic hydrocarbons (PAH) and phenolic substances in Frankfurter-type sausages depending on smoking conditions using glow smoke. Meat Science, 90(1), 176–184. Roseiro LC, Gomes A, Patarata L, Santos C. 2012. Comparative survey of PAHs incidence in Portuguese traditional meat and blood sausages. Food and Chemical Toxicology, 50(6), 1891–1896. Šimko P. 2005. Factors affecting elimination of polycyclic aromatic hydrocarbons from smoked meat foods and liquid smoke flavorings. Molecular Nutrition and Food Research, 49, 637–647. Stumpe-V̄ıksna I, Bartkeviˇcs V, Kuk¯are A, Morozovs A. 2008. Polycyclic aromatic hydrocarbons in meat smoked with different types of wood. Food Chemistry, 110(3), 794–797. Wretling S, Eriksson A, Eskhult GA, Larson B. 2010. Polycyclic aromatic hydrocarbons (PAHs) in Swedish smoked meat and fish. Journal of Food Composition and Analysis, 23(3), 264–272.

PART II

Raw Materials

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The Biochemistry of Meat and Fat Fidel Toldrá1 and Milagro Reig2 1

Instituto de Agroquímica y Tecnología de Alimentos (CSIC), Paterna, Valencia, Spain 2 Instituto de Ingeniería de Alimentos para el Desarrollo, Universitat Politècnica de València, Valencia, Spain

7.1 Introduction: muscle structure Skeletal muscle constitutes the most important part of meat. This is a voluntary and striated muscle with several nuclei located peripherally in the cell. The muscle is divided into sections by thin connective tissue layers, termed “perimysium,” and each section is divided into fibers by thin collagen fibers, termed “endomysium.” Each fiber contains about 1000 myofibrils, arranged parallel, which are responsible for the contraction of the muscle. The length of a muscle fiber may reach several centimeters, and its diameter will be about 50 μm. Myofibrils are composed of thick and thin filaments that overlap in alternative regions known as dark (A) and light (I) bands. These filaments are composed of the proteins responsible for muscle contraction and relaxation. The Z and M lines bisect each I and A band, respectively. The sarcomere is the distance between two consecutive Z lines. Its length is usually around 2–3 μm. Muscle fibers can be red or white, with each type having very different biochemical properties. Depending on the proportions of the two types of fiber, the appearance and properties of the muscle can vary significantly. Red muscle, which is rich in red fibers, has larger content of myoglobin and lipid and higher oxidative enzymatic activity, while white muscle, which is rich in white fibers, has a larger glycogen content and a higher glycolytic enzyme activity (Toldrá, 2006a). Red muscle is more aerobic in metabolism but slower in contraction than white muscle.

7.2 Meat composition Meat is basically composed of water, protein, lipid, minerals, and trace amounts of carbohydrate. An example of the typical composition of pork muscle is given in Table 7.1. Water is the major constituent, followed by proteins, but proportions can vary largely depending on the amount of fattening: the content of protein and water decrease as the amount of fat increases. The proteins, lipids, and enzymes found in meat and fat are briefly described in this section.

7.2.1 Muscle proteins Proteins constitute the major fraction of meat, approximately 15–22%. There are three main groups of proteins in muscle: myofibrillar, sarcoplasmic, and stromal. Each group’s constituent proteins and its localization are summarized in Table 7.2. 7.2.1.1 Myofibrillar proteins These are the main constituents of the myofibrils. The major proteins are myosin and actin, which provide the structural backbone of the myofibril. Regulatory proteins like tropomyosin and the troponins are involved in muscle contraction and relaxation. The Z-line proteins serve as bridges between the thin filaments of adjacent sarcomeres. Desmin connects adjacent myofibrils at the level of the Z-line. The longitudinal continuity and integrity of muscle cells are achieved by two very large proteins, titin and nebulin, which run in parallel to the long axis of the myofibril (Bandman, 1987). 7.2.1.2 Sarcoplasmic proteins These are water-soluble and comprise about 30–35% of the total protein in muscle. Sarcoplasmic proteins are quite diverse, including myoglobin (the natural pigment of meat) and many metabolic enzymes found in mithocondria, lysosomes, microsomes, nuclei, and free in the cytosol. The amount of myoglobin depends on the fiber type, the age of the animal, and the animal species (Kauffman, 2001). 7.2.1.3 Stromal proteins Fibers and muscles are surrounded by connective tissue (epimysium, perimysium, and endomysium). Collagen, which is the basic protein of this tissue, provides strength and support to the muscle structure. There are several types (I–V) of collagen, containing different polypeptide chains (up to 10 α-chains). Type I collagen is mainly found in the epimysium and perimysium, while Types III, IV, and V are found in the endomysium. Elastin is found in lower amounts, usually in artery walls, tendons, nerves, and ligaments, providing them with some elasticity (Toldrá & Reig, 2012).

Handbook of Fermented Meat and Poultry, Second Edition. Edited by Fidel Toldrá. © 2015 John Wiley & Sons, Ltd. Published 2015 by John Wiley & Sons, Ltd.

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Handbook of Fermented Meat and Poultry

7.2.2 Peptides and free amino acids Table 7.1 Approximate composition of pork lean muscle (expressed as g/100 g). Mean range of variation

Composition (g/100 g)

Moisture

72–76

Proteins

15–22

Myofibrillar 9–10 Sarcoplasmic 9–10 Stromal 2–3

Lipids

1.5–4.0

Triacylglycerols 1.5–3.5 Phospholipids 0.5–0.6 FFAs