Barley: Properties, Functionality and Applications [1° ed.] 0367819937, 9780367819934

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Barley

Barley

Properties, Functionality and Applications

By

Sneh Punia, PhD

CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2020 by Taylor & Francis Group, LLC CRC Press is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S. Government works Printed on acid-free paper International Standard Book Number-13: 978-0-367-81993-4 (Paperback) International Standard Book Number-13: 978-0-367-46280-2 (Hardback) Tis book contains information obtained from authentic and highly regarded sources. Reasonable eforts have been made to publish reliable data and information, but the author and publisher cannot assume responsibility for the validity of all materials or the consequences of their use. Te authors and publishers have attempted to trace the copyright holders of all material reproduced in this publication and apologize to copyright holders if permission to publish in this form has not been obtained. If any copyright material has not been acknowledged please write and let us know so we may rectify in any future reprint. Except as permitted under U.S. Copyright Law, no part of this book may be reprinted, reproduced, transmitted, or utilized in any form by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying, microflming, and recording, or in any information storage or retrieval system, without written permission from the publishers. For permission to photocopy or use material electronically from this work, please access www.copyright.com (http://www.copyright.com/) or contact the Copyright Clearance Center, Inc. (CCC), 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400. CCC is a not-for-proft organization that provides licenses and registration for a variety of users. For organizations that have been granted a photocopy license by the CCC, a separate system of payment has been arranged. Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identifcation and explanation without intent to infringe. Library of Congress Cataloging‑in‑Publication Data Names: Punia, Sneh, author. Title: Barley : properties, functionality and applications / by Sneh Punia, PhD. Description: Boca Raton : Taylor & Francis, [2020] | Includes bibliographical references and index. Identifers: LCCN 2019060089 (print) | LCCN 2019060090 (ebook) | ISBN 9780367819934 (paperback) | ISBN 9780367462802 (hardback) | ISBN 9781003019336 (ebook) Subjects: LCSH: Barley. | Barley--Nutrition. | Barley--Processing. Classifcation: LCC TX558.B35 P86 2020 (print) | LCC TX558.B35 (ebook) | DDC 641.3/316--dc23 LC record available at https://lccn.loc.gov/2019060089 LC ebook record available at https://lccn.loc.gov/2019060090 Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com and the CRC Press Web site at http://www.crcpress.com

Contents P R E FA C E ABOUT

THE

ix AUTHOR

xi

A B B R E V I AT I O N S CHAPTER 1

xiii

INTRODUCTION

1.1 1.2 1.3 1.4 1.5

Introduction History Production Grain Structure Chemical Composition 1.5.1 Starch 1.5.2 Dietary Fibres 1.5.3 Protein 1.5.4 Lipids 1.5.5 Vitamins 1.5.6 Minerals 1.5.7 Phenolic Compounds 1.6 Uses 1.7 Conclusions References CHAPTER 2

P HYS I CA L

2.1 2.2 2.3 2.4 2.5

AND

FU N C T I O N A L P R O P E R T I E S

Introduction Physical Properties Milling Hunter Color Characteristics Functional Properties

1 1 1 2 2 5 8 8 10 11 11 12 12 13 13 14 21 21 21 23 27 28 V

VI

C O N T EN T S

2.6 Pasting Properties 2.7 Termal Properties 2.8 Conclusions References CHAPTER 3

30 30 31 31

FU N C T I O N A L C O M P O N E N T S POTE NTIAL O F BARLE Y

AND

A N TI OX I DA N T

3.1 3.2 3.3 3.4

Introduction Health Benefts of Whole-Grain Cereals Mechanism of Action Classifcation of Bioactive Compounds 3.4.1 Phenolic Acids 3.4.2 Flavonoids 3.4.3 Tocopherols and Tocotrienols 3.4.4 Others 3.5 Bioactive Compounds in Whole-Grain Cereals 3.6 Phenolic Acids 3.7 Flavonoids 3.8 Tocopherols 3.9 Carotenoids 3.10 Tannins 3.11 Lignans 3.12 Alkylresorcinols 3.13 Phytosterols 3.14 β-Glucan 3.15 Conclusions References CHAPTER 4

β - G LUCANS: MECHANIS M

OF

ACTION

4.1 4.2 4.3 4.4 4.5

Introduction Extraction of β-Glucan Utilization as an Ingredient Mechanism of Action Health Benefts 4.5.1 Reduction of Cholesterol 4.5.2 Reduction of Blood Glucose/Diabetes 4.5.3 Hypertension 4.5.4 Anti-Carcinogenic Behaviour 4.5.5 Body Weight Management and Obesity 4.5.6 Immunity 4.6 Conclusions References CHAPTER 5

EFFECT OF PROCESSING ON NUTRITION A N TI OX I DA N T P RO P E R TI E S

5.1 5.2

Introduction Processing 5.2.1 Dehulling/Pearling

35 35 36 36 38 38 38 38 38 39 39 42 49 50 51 51 52 52 53 53 54 65 65 66 66 68 69 69 70 71 71 72 72 73 74

AND

77 77 80 80

VII

C O N T EN T S

5.2.2 5.2.3 5.2.4 5.2.5

Milling Germination Fermentation Termal Treatment 5.2.5.1 Extrusion 5.2.5.2 Roasting 5.2.5.3 Cooking 5.3 Conclusions References CHAPTER 6

S TA R C H : S T R U C T U R E , P R O P E R T I E S , A P P L I C AT I O N S

82 82 84 86 87 88 89 89 90 AND

6.1 Introduction 6.2 Starch Isolation and Purifcation 6.3 Chemical Structure 6.4 Chemical Composition 6.5 Granular Morphology 6.6 Swelling Power and Solubility 6.7 Starch Crystallinity 6.8 Pasting Properties 6.9 Flow and Dynamic Oscillatory Analysis 6.10 Termal Properties 6.11 In Vitro Digestibility 6.12 Applications 6.13 Conclusions References CHAPTER 7

S TA R C H M O D I F I C AT I O N S : P H Y S I C A L , C H E M I C A L , A N D E N Z Y M AT I C

7.1 7.2

7.3

7.4

Introduction Physical Modifcation 7.2.1 Termal Physical Modifcation 7.2.1.1 Pregelatinized 7.2.1.2 Hydrothermal Treatment 7.2.2 Nonthermal Physical Modifcation 7.2.2.1 High-Pressure Processing 7.2.2.2 Micronization 7.2.2.3 Ultrasonication 7.2.2.4 Pulse Electric Field Chemical Modifcations 7.3.1 Acetylation 7.3.2 Oxidation 7.3.3 Octenyl Succinic Anhydride 7.3.4 Acid Hydrolysis 7.3.5 Cross-Linking 7.3.6 Succinylation 7.3.7 Dual Modifcation Enzymatic Modifcations

97 97 97 99 100 102 105 106 106 109 111 113 114 115 115 123 123 124 124 124 130 131 132 132 133 133 134 134 135 136 136 137 137 138 139

VIII

C O N T EN T S

7.5 Conclusions References CHAPTER 8

M A LT

AND

M A LT P R O D U C T S

8.1 8.2

Introduction Malting Process 8.2.1 Steeping/Soaking 8.2.2 Germination 8.3 Drying 8.4 Malt Extracts and Syrups 8.4.1 Extracts 8.4.2 Syrups 8.4.3 Dry diastatic malts 8.4.4 Special malts 8.5 Malt Types 8.5.1 Pale Lager Malt 8.5.2 Pale Ale Malt 8.5.3 Vienna Malt 8.5.4 Munich Malt 8.4.5 Caramel Malt 8.5.6 Brown and Amber Malts 8.5.7 Chocolate and Black Malts 8.6 Food Applications 8.6.1 Bakery Goods 8.6.2 Malted Milk Powder 8.6.3 Beer 8.6.3.1 Milling 8.6.3.2 Mashing 8.6.3.3 Addition of hops 8.6.3.4 Fermentation/pitching 8.6.3.5 Maturation 8.6.3.6 Finishing, carbonation and bottling 8.6.4 Malt Vinegar 8.7 Conclusions References CHAPTER 9

P R O D U C T F O R M U L AT I O N

9.1 Introduction 9.2 Breads 9.3 Flatbreads 9.4 Noodles and Pastas 9.5 Biscuits and Cookies 9.6 Cakes 9.7 Tarhana 9.8 Tortillas 9.9 Barley Tea 9.10 Conclusions References INDEX

140 140

149 149 149 149 150 151 152 152 153 153 153 153 153 154 154 154 154 155 155 155 155 156 156 156 158 159 160 161 161 161 161 162

165 165 166 170 171 173 175 175 176 176 177 177

18 3

Preface Te consumption of cereal grains has gained popularity with wholegrain products being regarded as “healthy foods” because of their potential protection against lifestyle and diet-related disorders. Te importance and health benefts of regular cereal grain consumption in the prevention of chronic diseases are a focus of many research laboratories. Te importance of barley for human health has been boosted up in recent years by research which showed that barley is a very rich source of phenolic compounds, dietary fbres, vitamins, and minerals, and a moderate source of amylose starch as well – all play modulating roles in chronic degenerative diseases. Exploring the properties of barley provides a basis for better utilizing barley as well as for further development of barley as a sustainable crop. Tis book will explore knowledge about barley production, grain structure, chemistry and nutritional aspects, primary processing technologies, product formulations etc. Chapter 1 deals with barley classifcation, history, nutritional aspects, and the health benefts of barley. Barley contains complex carbohydrates (mainly starch), has low fat content, and is moderately well balanced in terms of protein to meet amino acid requirements, as well as minerals, vitamins (particularly vitamin E), and antioxidant polyphenols. Chapter 2 discusses the physical properties (geometric mean diameter, arithmetic mean diameter, sphericity, surface area, bulk density, true density, porosity, angle of repose, etc.), functional properties (water absorption capacity, oil absorption capacity, foaming capacity and stability, emulsion capacity and stability), colour characteristics, pasting, and thermal properties of barley. Te physical properties of cereal grains are required to design food-processing appliances used during harvesting, separating, cleaning, handling and storing of grains and convert them into food, feed, and fodder. Functional properties play important roles in the physical behaviour and afect the sensory characteristics of foods. Chapter 3 explores the role of  β-glucans in the prevention of many diseases and their underlying mechanisms of IX

X

P REFAC E

action, as well as their potential in food applications. Chapter 4 discusses the functional and antioxidant potential of barley. Barley has a number of bioactive compounds that include phenolic acids, favonoids, tocopherols, tannins, β-glucan, phytosterols, alkylresorcinols, etc. Tis chapter reviews the bioactive compounds and the antioxidant activity of barley and their unique contribution to health. Chapter 5 focuses on understanding the infuence of processing such as dehulling, pearling, milling, germination, fermentation, and thermal treatments (roasting, extrusion, cooking, etc.) on the nutritional and phytochemicals of barley grains in retaining its health-benefting properties. Chapter 6 deals with starch structure, properties, and applications. In this chapter, starch isolation methods, starch structure, pasting, rheological, morphological, digestibility properties, and applications of barley starch are elaborated. Barley starch has comparable properties with other cereal starches, so it may be used as a substitute for cereal starches. During processing, the texture and appearance of the product are altered, so to overcome these undesirable changes, starch needs to be modifed. Diferent methods of starch modifcations such as physical, chemical, and enzymatic are explored in Chapter 7. Chapter 8 explores the utilization of malt and malt products in food. Barley is the primary cereal processed into malt and is mainly used for brewing and additionally in distilling, vinegar production, and commercially as a food ingredient to enhance colour, enzyme activity, favour, and sweetness as well as for nutritional amelioration. In bakery products, diastatic malts are used as dough conditioners whereas nondiastatic malts are used to provide colour and strong favours. Chapter 9 deals with the incorporation of barley as a replacement in many wheat-based products, i.e. breads, cookies, biscuits, chapattis, pasta, noodles, cakes, tortillas, tarhanas, etc., so that the content of total and soluble fbre increases in the food products, improving their physiological efcacy and providing health benefts. Tis book will be useful for students, academicians, researchers, and other interested professionals working on starch and new product formulations and those in malt and brewing industries. Tere are many books available on barley but this book is designed in such a way that it deals with important aspects related to barley. Te author appreciates further comments/information for future reference.

About the Author Sneh Punia, PhD, is presently working as Assistant Professor in the Department of Food Science and Technology, CDLU, Sirsa, India. Her area of interests includes antioxidants, starch, and the development of new products. She has published more than 20 research papers in national and international journals. She has presented more than 25 research papers in various national and international conferences. She also serves as the reviewer for various international journals.

XI

Abbreviations BC BCE BD Ca CO2 CsCl Cu Da DP DPPH oC oF DS DSC E. coli EC ECH ES FAE FC FDA Fe FS FV Gʹʹ Gʹ GA g

Before Christ Before the Common Era breakdown viscosity calcium carbon dioxide cesium chloride copper dalton degree of polymerization 2,2-diphenyl-1-picrylhydrazyl degree Celsius degree Fahrenheit degree of substitution diferential scanning calorimetry Escherichia coli emulsion capacity epichlorohydrin emulsion stability ferulic acid equivalent foaming capacity Food and Drug Administration iron foaming stability fnal viscosity loss modulus storage modulus gibberellic acid gram X III

XIV

GI GPC GT h H 2SO4 H3PO4 HMT HNO3 HPLC HPP HPSEC-MALS-RI HPSEC-RI HTST IDF K kcal kHz K LDL m.c. Mg µg mg ml M Mn MPa Mrad n NSPs O2 OAC OSA P PEF

A B B RE V IATI O NS

glycemic index gel permeation chromatography gelatinization temperature hour sulphuric acid phosphoric acid heat-moisture treatment nitric acid high-performance liquid chromatography high-pressure processing high-performance size-exclusion-multiangle light scattering-refractive index high-performance size-exclusion refractive index high temperature short time insoluble dietary fbre consistency coefcient [Pa·sn ] kilocalories kilohertz potassium low-density lipoproteins moisture content magnesium microgram milligram millilitre molar manganese megapascal millirads fow behaviour index nonstarch polysaccharide oxygen oil absorption capacity octenyl succinic anhydride phosphorus pulse electric feld

A B B RE V IATI O NS

PGS pH POCl3 PPO PV RDS RNS ROS rpm RS RVA SCFA SDF SDS SEM Si SP STMP STPP Tc TFC Tg To TPC Tp TV UV Zn α β γ˙ γ δ ΔHgel τ

Pregelatinized starches power of hydrogen phosphoryl chloride polyphenol oxidase peak viscosity rapidly digestible starch reactive nitrogen species reactive oxygen species revolutions per minute resistant starch rapid Visco analyzer short-chain fatty acids soluble dietary fbre slowly digestible starch scanning electron microscope silicon swelling power sodium trimetaphosphate sodium tripolyphosphate endset temperature total favonoids content glass transition temperature onset temperature total phenolic content peak temperature trough viscosity ultraviolet zinc alpha beta shear rate [s−1] gamma delta enthalpy of gelatinization shear stress [Pa]

XV

1 I NTRODUCTION

1.1 Introduction

Genus: Hordeum Tribe: Triticeae Subfamily: Festucoidese Family: Gramineae Barley (Hordeum vulgare, vulgare L., 2n=14, diploid) is a grass belonging to the family Poaceae, the tribe Triticeae, and the genus Hordeum. Te basic chromosome number of the genus Hordeum is 7, and all cultivated barleys are self‑fertilizing, diploid annuals (MacGregor, 2003). Tis tribe is characterized as having spike inforescences, a base chromosome number ×=7,   and large genomes (Ullrich, 2014). It is an ancient and highly adaptable functional cereal crop that is produced in climates ranging from subarctic to subtropical. Te frst formal system of barley classifcation was established by Linnaeus (1753), who recognized four cultivated species. It consists of two six‑rowed species, namely H. vulgare L., with lax spikes, and H. hexastichon L., with dense spikes, and two two‑rowed species, namely H. distichon L., with lax spikes, and H. zeocriton L., with dense spikes. Tere is a great diversity in the morphological forms of barley, which include spring, winter, 6‐row, 2‐row, awned, awnless, hooded, covered and naked (hull‐less), feed (forage and grain), malting, and food type (Stanca et al., 2016). Naked barley has recently attracted more and more interest among food scientists and technologists because of its high soluble dietary fbres, β‑glucans and arabinoxylan content, and its high malt quality and ease of processing (Wang et al., 2011; Zheng et al., 2012). 1.2 History

Historically, barley has been an important food source in many parts of the world, including Asia, northern and eastern Europe, Middle East, 1

2

BA RL E Y

and North Africa (Chatterjee and Abrol, 1977; Newman and Newman, 2006). Barley cultivation originated in the highlands of Ethiopia and Southeast Asia about 10,000 years ago. Archaeological remains of barley grains found at various sites in the Fertile Crescent (the ancient name of the area that includes Iraq, with small portions of Iran, Kuwait, Turkey, Syria, Jordan, Israel, Lebanon, and the West Bank) (Zohary and Hopf, 2000) indicate that the crop was domesticated about 8000 BCE. Archaeological evidence dates barley cultivation to 5000 BCE in Egypt (Sun and Gong, 2009; Zhou, 2010), 2350 BCE in Mesopotamia, 3000 BCE in northwestern Europe, and 1500 BCE in China. In the last decade, Europe has produced around 60% of the world tonnage of barley, with Asia and the Americas producing 15% and 13%, respectively (FAO, 2019). 1.3 Production

Today, 80–90% of barley grain yield throughout the world is earmarked for livestock feed; about 10% is slated as malt production for beer, whisky, and other alcoholic beverages; and only a very small fraction is still directly consumed by man (Stanca et al., 2016). At present, only 2% of barley is used for human consumption (Baik and Ullrich, 2008). Globally, barley ranks fourth after wheat, rice, and corn in cereal crops with a production of 147,404,262 tonnes under an area of 47,009,175 ha. Regionally, Europe has the majority share (60.4%), followed by Asia (14.4%), America (11.4%), Oceania (9.4%), and Africa (4.5%) (FAO, 2017) (Figure 1.1). Te top producers in terms of production quantity are Russia (20,598,807 tonnes), Australia (13,505,990 tonnes), Germany (10,853,400 tonnes), France (10,545,427 tonnes), and Ukraine (8,284,890 tonnes) (FAO, 2017) (Figure 1.2). In India about 656,000 hectares of land is under barley cultivation with a total barley production of 1,750,000 tonnes (FAO, 2017). Due to changes in climatic conditions in the main producer countries for barley production, annual fuctuations occur (Figures 1.3 and 1.4). 1.4 Grain Structure

Cereals are members of the family Gramineae and produce dry, one‑ seeded fruits called grains, which consist of a fruit coat (pericarp)

3

IN T R O D U C TI O N

Africa (4.5%) America (11.4%) Asia (14.4%) Europe (60.4%) Oceania (9.4%)

Figure 1.1 Production share of barley worldwide (FAO, 2017). 25000000

Tonnes

20000000 15000000 10000000 5000000 0

Figure 1.2 Top producers of barley worldwide (FAO, 2017).

and a seed (Lemmens et al., 2019). Barley grains are generally larger and more pointed than wheat and have a bright, light yellow colour (Figure 1.5). Te colour of barley may vary from light yellow to purple, violet, blue, and black. Tis versatility in grain colour is mainly caused by the anthocyanin content in the hull, pericarp, and/or aleurone layer (Baik and Ullrich, 2008). Generally, sound barley grain has a bright light yellow or of‑white colour, whereas any discoloration in barley grain develops undesirable favours during the malting process (Li et al., 2003). According to Pomeranz and Shands (1974), barley has many characteristics that make it a good food candidate. Ideal food barley is clean, bright yellow‑white, plump, thin‑hulled,

4

BA RL E Y

2000000 1800000 1600000 1400000 1200000 1000000 800000 600000 400000 200000 0

2011 2012 2013 2014 2015 2016 2017 Area (ha)

Produc˜on (tonnes)

Figure 1.3 Production and area cultivated for barley in India (FAO, 2017). 160000000 140000000 120000000 100000000 80000000 60000000 40000000 20000000 0

2011 2012 2013 2014 2015 2016 2017 Area (ha)

Produc˜on (tonnes)

Figure 1.4 Production and area cultivated for barley worldwide (FAO, 2017).

medium‑hard, and uniform in size. Grain is comprised of husk – formed from the lemma (dorsal husk or hull), palea (ventral husk or hull), pericarp, testa, and aleurone layers, germ or embryo, and the endosperm (Figure 1.6). Te husk and pericarp, the two outermost and protective tissues of the barley grain (Izydorczyk and Dexter, 2016) and lemma and palea of the hull cover the caryopsis (kernel)

IN T R O D U C TI O N

Figure 1.5

5

Barley grains.

which includes pericarp, seed coat, and endosperm. Endosperm is surrounded by living organ embryo with the aleurone layers (Arendt and Zannini, 2013; Fox, 2009). Figure 1.6 shows the structure and individual components of the grain. 1.5 Chemical Composition

Barley is rich in protein, carbohydrates, dietary fbres, minerals, and vitamins. As a comprehensive nutritive cereal whole barley grain consists of about 65–68% starch, 10–17% protein, 4–9% β‑glucan, 2–4% free lipids, and 1.5–2.5% minerals (Punia and Sandhu, 2015; Baik and Ullrich, 2008; Quinde et al., 2004; Izydorczyk et al., 2000; Czuchajowska et al., 1998). Li et al. (2001) reported 80% complex carbohydrates, 3.7–7.7% β‑glucans, 11.5–14.2% proteins, 4.7–6.8% lipids, and 1.8–2.4% ash, respectively, in naked barley. Izydorczyk et al. (2000) reported β‑glucans of 7.49% (w/w) for high‑amylose barley, followed by waxy barley (6.86%), zero amylose waxy barley (6.30%),

6

BA RL E Y

Figure 1.6 Structure of barley grain.

and normal barley (4.38%). Signifcant variations were found for chemical composition of barley (Table 1.1). Te distribution of various chemical constituents is not uniform throughout the component tissues of barley grain. Te hull or husk comprises of 7.6–12.9% of grain (Punia and Sandhu, 2015; Zieliński and Kozłowska, 2000) and is rich in cellulose, insoluble arabinoxylans, lignin, polyphenols, and minerals (major proportion)

80

77.4–82.2

67.6

65–68

STARCH (%) 2.47–2.67 3.3 3.2–4.2

12.7–12.42 11.2 9.1–13.6 8–17 10.9–13.6 11.5–14.2 13.6 4.7–6.8 2.60

LIPIDS (%)

PROTEIN (%)

Chemical Composition of Barley

CARBOHYDRATE (%)

Table 1.1

2.24–2.55 1.8–2.4

2.35–2.56 1.28 1.38–1.77

ASH (%)

1.5–3

MINERALS (%)

3.6–9 3.8–5.6 3.7–7.7 6.21

3.65–3.67

β-GLUCAN (%)

Bader Ul Ain et al. (2018) Aprodu and Banu (2017) Punia and Sandhu, (2015) Baik and Ullrich (2008) Quinde et al. (2004) Li et al. (2001) (naked barley) Czuchajowska et al. (1998)

REFERENCES

IN T R O D U C TI O N

7

8

BA RL E Y

(MacGregor, 1998). Proanthocyanidins and catechins occur between the cuticularized layers of testa. Te pericarp contains cellulose, lignin, and arabinoxylan. Te endosperm, which contributes to 75–80% of the total kernel weight, is rich in starch which is embedded in a protein matrix (MacGregor and Bhatty, 1993). Te cell walls in the endosperm are mainly composed of β‑glucan (70–75%), arabinoxylans (20–25%), and protein (5–6%) with minor amounts of glucomannans, cellulose, and phenolic compounds (Jadhav et al., 1998, MacGregor, 1998). Te aleurone, the outer most layer of the endosperm comprising of arabinoxylans (67–71%), β‑glucan (22–26%), and proteins (16%) contributes to about 5–10% of the total kernel weight. Te embryo, which constitutes 2–4% of grain is rich in lipids (13–17%), protein and amino acids (34%), sucrose and rafnose (5–10%), arabinoxylan, cellulose and pectin (8–10%), and ash (5–10%) (Izydorczyk and Dexter, 2016; MacGregor and Bhatty, 1993). 1.5.1 Starch

Carbohydrates are major components, with starch being the principal constituent of barley, accounting for 51–64% (Holtekjølen et al., 2006). Starch is made up of two components, amylose and amylopectin. Amylose is a linear polymer made up of glucose molecules linked via α‑(1‑4) glucosidic bonds and amylopectin is the larger polymer with α‑ (1‑4) glucosidic and α‑(1‑6) glucosidic linkages, which form a branched structure (Hough, 1985). Endosperm fraction of barley is abundant in starch, whereas aleurone, subaleurone, and germ tissues contain smaller proportions of starch. Amylose content of barley starch varies from 0 to 5% in waxy, 20 to 30% in normal, and up to 45% in high‑ amylose barley (Bhatty and Rossnagel, 1997). Izydorczyk et al. (2000) reported starch content of 60.7%, 52.9%, 54.0%, and 53.9% for normal barley, high‑amylose, waxy, and zero amylose waxy barley, respectively. Composition of carbohydrates of barley is reported in Table 1.2. 1.5.2 Dietary Fibres

Dietary fbre refers to the non‑digestible carbohydrate entity, which is impervious to enzymatic assimilation and absorption in the small

9

IN T R O D U C TI O N

intestine of human. Dietary fbres are classifed into two categories according to their water solubility: insoluble dietary fbre (IDF) and soluble dietary fbre (SDF) (Dhingra et al., 2012; Lattimer and Haub, 2010). Dietary fbre consists of non‑starch polysaccharide (NSPs) in cereal grains and NSPs in barley include cell wall components such as β‑glucans, arabinoxylans, cellulose, glucomannan, and fructon (Choct, 1997; Morrison, 1993; Henry, 1987) and accounts for 23–41% in barley. Te hulled varieties have a signifcantly higher content of total NSP than hull‑less barley, probably due to the contribution of cellulose and arabinoxylans from the hull in the hulled barley. Te dominant fbre components, β‑glucans and arabinoxylans, are located mainly in the cell walls of the endosperm and the aleurone layer (Holtekjølen et al., 2006). Table 1.2 Composition of Carbohydrates of Barley Carbohydrates Starch Non-starch polysaccharides Total fbres

Soluble

Insoluble Lignin Cellulose Arabinoxylans Sugars Glucose Arabinose Xylose Mannose Galactose Rhamnose and fucose

PERCENTAGE (%)

REFERENCES

77.4–82.2 65–68 22.6–41.1 17.13–17.70 16.20 24 13.4 11–34 4.73–5.70 4.8 3–20 12–12.40 8.6 0.2–2.0 8.0–17.7 2.0–2.9 3.5–6.5 0.8–1.1

Punia and Sandhu (2015); Li et al. (2001) Baik and Ullrich (2008) Holtekjølen et al. (2006) Bader Ul Ain et al. (2018) Aprodu and Banu (2017) Feng et al. (2017) Beloshapka et al. (2016) Fastnaught (2001) Bader Ul Ain et al. (2018) Beloshapka et al. (2016) Fastnaught (2001) Bader Ul Ain et al. (2018) Beloshapka et al. (2016) Newman and Newman (2008) Holtekjølen et al. (2006) Xue et al. (1997) Izydorczyk and Dexter (2008) Holtekjølen et al. (2006)

11.9–24.3 3.7–5.7 5.3–12.9 0.7–1.1 0.8–1.3 Trace amounts

Holtekjølen et al. (2006) Holtekjølen et al. (2006) Holtekjølen et al. (2006) Holtekjølen et al. (2006) Holtekjølen et al. (2006) Holtekjølen et al. (2006)

10

BA RL E Y

Of all the TDF components of barley, β‑glucans are probably the most important in terms of human diet and health benefts. β‑Glucan is composed of linear homopolymers of D‑glucopyranosyl residues linked mostly via 2–3 consecutive β‑(1→4) linkages that are separated by a single β‑(1→3) linkage (Knudsen, 2014). In barley, β‑glucans ranges from 2.5 to 11.3% (Izydorczyk and Dexter, 2008) and is infuenced by both genetic and environmental factors and the interactions between the two (Andersson et al., 1999). Arabinoxylans consist of long chains of 1,4‑D‑xylose residues to which 1–2 or 1–3 bond arabinose residues are linked in some places (Kunze, 2010). Te arabinoxylan content of barley grain is estimated to range from 4 to 7% by weight, being primarily concentrated in the aleurone (71%) and starchy endosperm (20%) (Henry, 1987; Morrison, 1993). Six‑rowed barley cultivars generally contain slightly higher levels of arabinoxylans than two‑rowed cultivars (Fleury et al., 1997). Cellulose is a long‑chain polymer of (1,4)‑β‑linked glucose molecules, which renders it insoluble and indigestible by humans. Barley contains between ∼5% (hulled barleys) and ∼3% (hull‑less barleys) cellulose (Xue et al., 1997) and is mainly concentrated in the husk and other outer layers. Te predominating sugar components in barley were glucose (11.9–24.3%), xylose (5.3–12.9%), and arabinose (3.7–5.7%), whereas the contents of mannose and galactose were considerably lower (0.7–1.1% and 0.8–1.3%, respectively) (Holtekjølen et al., 2006). 1.5.3 Protein

Barley grains and its by‑products are abundant and afordable protein sources which contain 7–25% and 20–30% (w/w) protein, respectively (Yalçin et al., 2008; Ullrich, 2002). On the basis of solubility, they are categorized into four groups: albumin (water‑soluble fraction), globulin (salt‑soluble fraction), prolamin or hordein (alcohol‑soluble fraction), and glutelins (alkali‑soluble fraction) as described by Osborne (1924). Hordein and glutelin are the two major endosperm storage proteins of barley (30–55% and 35–40%, respectively) (Jonassen et al., 1981; Kirkman et al., 1982; Newman et al., 1978), whereas albumin and globulin proteins are enriched in the bran and germ layers

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(Finnie and Svensson, 2009). Hordeins, the major storage proteins in the endosperm, have been classifed on the basis of amino acid composition into three groups: sulfur‑rich, sulfur‑poor, and high‑molecular‑weight prolamins (Newman and Newman, 2008). Te barley non‑storage proteins are found primarily in the aleurone and embryo, and account for 15–30% of the total grain nitrogen with albumins and globulins as the major representatives. Barley endosperm protein is rich in prolamin storage proteins (hordeins) and has moderate nutritional quality (Newman and McGuire, 1985). Te amino acid composition of barley protein is quite similar to the other cereal grains. High glutamic acid and proline contents and relatively low amounts of basic amino acids characterize the barley grain (Arendt and Zannini, 2013). Barley proteins have been recognized as a rich source of the limiting essential amino acids (lysine, threonine, methionine and tryptophan) (Newman et al., 1978). 1.5.4 Lipids

Barley has low lipid content (2–4%) (Price and Parsons, 1975; Welch, 1978) as compared to other cereal grains. Price and Parsons (1979) reported that endosperm, germ, and hull possessed 77%, 18%, and 5% of total lipid content. In the endosperm, the main part of the lipid is deposited in the aleurone layer. Among fatty acids, linoleic acid is the major fatty acid present in barley, (52.4–58.3%), followed by palmitic acid (21.4–28.7%), oleic acid (10.4–16.9%), linolenic acid (4.5–7.3%), and stearic acid (0.6–1.8%) (Welch, 1978). 1.5.5 Vitamins

Vitamins are nutritional components produced by plants. Cereal grains are well known to be good sources of certain vitamins, particularly some of the B‑complex vitamins. Te barley kernels contain all the vitamins and choline with the exception of vitamins A, D, K, B12, and C (Arendt and Zannini, 2013). Of the major cereals, barley contains the highest amount of fat‑soluble vitamin E (tocols) (Kerckhofs et al., 2002). Barley grains contain all eight isomers – four tocopherols (α‑T, β‑T, γ‑T, δ‑T) and four tocotrienols (α‑T3,

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β‑T3, γ‑T3, δ‑T3) (Morrison, 1978), with α α‑T3, γ‑T3 being the most dominant (Moreau et al., 2007; Nielsen and Hansen, 2008). While the majority of tocopherols are found in the embryo, tocotrienols are more evenly dispersed throughout the kernel (Peterson, 1994). Andersson et al. (2008) reported in barley tocotrienol contributed 76.8% of total tocols, indicating that barley is one of the richest sources of tocotrienols among cereal grains (Ward et al., 2008). Vitamin B1 (thiamine) is deposited mainly in the aleurone layer (32%) and scutellum (62%) of the grain, while vitamin B2 (ribofavin) is mainly found in the aleurone layer (37%) and endosperm (32%). Barley contains the highest nicotinic acid level of all cereals, and this is concentrated in the aleurone layer (61%) (Newman and Newman, 2008). Vitamin B1 (thiamine) is deposited mainly in the aleurone layer (32%) and scutellum (62%) of the grain, while vitamin B2 (ribofavin) is mainly found in the aleurone layer (37%) and endosperm (32%). Barley contains the highest nicotinic acid level of all cereals. (Newman and Newman, 2008). 1.5.6 Minerals

Barley contains 2–3% minerals (Newman and Newman, 2008). Te embryo exhibits high concentrations of Mn (>30%), while the aleurone sub‑fractions had the highest concentration of Mg. Cu, Zn, and Fe distribution is also much greater in the ventral side compared with the dorsal side. Te most abundant macro‑elements found in barley are P, K, and Si, while among the micro‑elements, Fe, Mn, and Zn are the main representatives (Arendt and Zannini, 2013). Phosphorus is the most important element, in nutritional terms, and in the barley kernel it is present in the form of phytic acid (myoinositol), mainly localized in barley embryo and aleurone tissues representing 65–75% of total kernel phosphorus (Raboy, 1990). 1.5.7 Phenolic Compounds

Barley has a number of bioactive compounds that include phenolic acids (Mattila et al., 2005), favonoids (Tamagawa et al., 1999), tocopherols (Panfli et al., 2003), tannins (Collins, 1986), and

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alkylresorcinols (Ross et al., 2003). Details of phenolic compounds in barley are discussed in Chapter 3. 1.6 Uses

Barley is primarily used for livestock feed, as an ingredient in malt for the production of beer, and only a small portion of barley is used for human food. Barley grain’s low lipid content, high carbohydrate (starch), balanced amino acid profle, vitamin E, minerals, dietary fbres, and phenolic compounds provide a key to nutritionists and food scientists to formulate various healthy food products. In industrial applications, barley is processed into malt (grain with high enzyme activity and modifed endosperm) and is mainly used for brewing and distilling (Kochevenko et al., 2018). Barley has been used to formulate various healthy food products such as pasta and bread (Stanca et al., 2016), tortillas (Ames et al., 2006), cakes (Tashi, 2005; Newman and Newman, 1991), beer (Tashi, 2005; Kerssie and Goitom, 1996), bread, cookies, and extruded snack foods (Newman and Newman, 1991), noodles (Newman and Newman, 1991; Change and Lee, 1974). Barley starch is of consistent quality and is ideal for various industrial uses. Te large variations in composition, structures, and physicochemical properties of both native barley starches provide a basis to understand the variations in the quality of barley‑ based products, as well as for their diverse uses in food and non‑food industries. Tey may have potential to be used as feed ingredients and adhesives in paperboard, for clay removal in potash mining, and sizing and coating in paper production, for the production of alcohol, dextrins, sweeteners, and lactic acid, and for encapsulation of functional food ingredients (Vasanthan and Hoover, 2009). 1.7 Conclusions

Barley is one of the most important ancient grain crops, and has been evolved through domestication to today as a major world crop based on acreage and production. It has great potential to reclaim some of its prominence as a food grain, largely due to the dietary fbre, β‑glucan, protein, and starch content, which provide physical and functional

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characteristics to food products. It is recommended that regular consumption of barley helps in the prevention and treatment of cardiovascular diseases, diabetes, etc.

References

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Collins, F. 1986. Oat phenolics: Avenanthramides, novel substituted N‑cinnamoylanthranilate alkaloids from oat groats and hulls. Journal of Agricultural and Food Chemistry 37:60–66. Czuchajowska, Z., Klamczynski, A., Paszczynska, B., and Baik, B.‑K. 1998. Structure and functionality of barley starches. Cereal Chemistry 75(5):747–754. Dhingra, D., Michael, M., Rajput, H., and Patil, R. T. 2012. Dietary fber in foods: A review. Journal of Food Science and Technology 49(3):255–266. FAOSTAT. 2017. FAO—Food and Agriculture Organization of the United Nations. Available from FAOSTAT Statistics database‑agriculture. Rome, Italy: Food and Agriculture Organization of the United Nations. FAOSTAT. 2019. FAO—Food and Agriculture Organization of the United Nations. Available from FAOSTAT Statistics database‑agriculture. Rome, Italy: Food and Agriculture Organization of the United Nations. Available online: http://www.fao.org/faostat/en/(accessed on 28 March 2019). Fastnaught, C. E. 2001. Barley fbre. In: Cho, S., and Dreher, M. (eds.), Handbook of Dietary Fibre. New York: Marcel Dekker. Feng, Z., Dou, W., Alaxi, S., Niu, Y., and Yu, L. L. 2017. Modifed soluble dietary fber from black bean coats with its rheological and bile acid binding properties. Food Hydrocolloids 62:94–101. Finnie, C., and Svensson, B. 2009. Barley seed proteomics from spots to structures. Journal of Proteomics 72:315–324. Fleury, M. D., Edney, M. J., Campbell, L. D., and Crow, G. H. 1997. Total, water‑soluble and acid‑soluble arabinoxylans in western Canadian barleys. Canadian Journal of Plant Science 77(2):191–196. Fox, G. P. 2009. Chemical composition in barley grains and malt quality. In: G. Zhang, , C. Li, Genetics and Improvement of Barley Malt Quality. Berlin/Heidelberg: Springer, 63–98. Henry, R. J. 1987. Pentosan and (1 → 3),(1 → 4)‑β‑glucan concentrations in endosperm and wholegrain of wheat, barley, oats and rye. Journal of Cereal Science 6(3):253–258. Holtekjølen, A. K., Uhlen, A. K., Bråthen, E., Sahlstrøm, S., and Knutsen, S. H. 2006. Contents of starch and non‑starch polysaccharides in barley varieties of diferent origin. Food Chemistry 94(3):348–358. Hough, J. S. 1985. Te Biotechnology of Malting and Brewing. Cambridge Studies in Biotechnology 1. Cambridge: Cambridge University Press. Izydorczyk, M. S., and Dexter, J. E. 2008. Barley β‑glucans and arabinoxylans: Molecular structure, physicochemical properties, and uses in food products–A review. Food Research International 41(9):850–868. Izydorczyk, M. S., and Dexter, J. E. 2016. Barley: Milling and Processing. In: Reference Module in Food Science. Oxford: Elsevier. Izydorczyk, M. S., Storsley, J., Labossiere, D., MacGregor, A. W., and Rossnagel, B. G. 2000. Variation in total and soluble β‑glucan content in hulless barley: Efects of thermal, physical, and enzymic treatments. Journal of Agricultural and Food Chemistry 48(4):982–989.

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Jadhav, S. J., Lutz, S. E., Ghorpade, V. M., and Salunkhe, D. K. 1998. Barley: Chemistry and value‑added processing. Critical Reviews in Food Science 38(2):123–171. Jonassen, I. B., Ingversen, J., and Brandt, A. 1981. Synthesis of SP II albumin, β‑amylase and chymotrypsin inhibitor CI‑1 on polysomes from the endoplasmic reticulum of barley endosperm. Carlsberg Research Communications 46:175–181. Kerckhofs, D. A. J. M., Brouns, F., Hornstra, G., and Mensink, R. P. 2002. Efects on the human serum lipoprotein profle of β‑glucan, soy protein and isofavones, plant sterols and stanols, garlic and tocotrienols. Te Journal of Nutrition 132:2494–2505. Kerssie, M., and Goitom, A. L. 1996. Barley utilization. In: Gebre, H., and Joop, V. L. (eds.), Barley Research in Ethiopia: Past Works and Future Prospects, First Barley Research Review Workshop. Addis Ababa: IAR/ ICARDA, 167–170. Kirkman, M. A., Shewry, P. R., and Mifin, B. J. 1982. Te efect of nitrogen nutrition on the lysine content and protein composition of barley seeds. Journal of the Science of Food and Agriculture 33:115–127. Knudsen, K. E. B. 2014. Fiber and nonstarch polysaccharide content and variation in common crops used in broiler diets. Poultry Science 93(9):2380–2393. Kochevenko, A., Jiang, Y., Seiler, C., Surdonja, K., Kollers, S., Reif, J. C., et al. 2018. Identifcation of QTL hot spots for malting quality in two elite breeding lines with distinct tolerance to abiotic stress. BMC Plant Biology 18:106. Kunze, W. 2010. Raw materials. In: Kunze, W. (ed.), Technology Brewing and Malting. Berlin: VLB, 39–112. Lattimer, J. M., and Haub, M. D. 2010. Efects of dietary fber and its components on metabolic health. Nutrients 2(12):1266–1289. Lemmens, E., Moroni, A. V., Pagand, J., Heirbaut, P., Ritala, A., Karlen, Y., Delcour, J. A., et al. 2019. Impact of cereal seed sprouting on its nutritional and technological properties: A critical review. Comprehensive Reviews in Food Science and Food Safety 18(1):305–328. Li, J., Kaneko, T., Qin, L. Q., Wang, J., and Wang, Y. 2003. Efects of barley intake on glucose tolerance, lipid metabolism, and bowel function in women. Nutrition 19(11–12):926–929. Li, J. H., Vasanthan, T., Rossnagel, B., and Hoover, R. 2001. Starch from hull‑less barley: I. Granule morphology, composition and amylopectin structure. Food Chemistry 74:395–405. Linnaeus, C. 1753. Species Plantarum. Stockholm: Impensis Laurentii Salvii. MacGregor, A. W. 2003. Barley. In: B. Caballero, L. C. Trugo, and P. M. Finglas, Encyclopedia of Food Sciences and Nutrition. Academic press: US, 379–382. MacGregor, A. W., and Bhatty, R. S. (eds.). 1993. Barley: Chemistry and Technology. St. Paul, MN: American Association of Cereal Chemists, 80.

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MacGregor, S. 1998. Composition of barley related to food uses. Paper Presented at the International Food Barley Program. Canadian International Grains Institute in Winnipeg, Manitoba, Canada. Mattila, P., Pihlava, J. M., and Hellström, J. 2005. Contents of phenolic acids, alkyl‑ and alkenylresorcinols, and avenanthramides in commercial grain products. Journal of Agricultural and Food Chemistry 53:8290–8295. Moreau, R. A., Wayns, K. E., Flores, R. A., and Hicks, K. B. 2007. Tocopherols and tocotrienols in barley oil prepared from germ and other fractions from scarifcation and sieving of hulless barley. Cereal Chemistry 84:587–592. Morrison, W. R. 1978. Wheat lipid composition. Cereal Chemistry 55:548–558. Morrison, W. R. 1993. Barley lipids. In: Macgregor, A. W., and Bhatty, R. S. (eds.), Barley: Chemistry and Technology. St Paul, MN: AACC International, Inc., 73–130. Newman, C. W., El‑Negoumy, A. M., and Eslick, R. F. 1978. Replacing soy protein in swine diets with high‑protein barley and amino acids. Journal of Animal Science 46:161–166. Newman, C. W., and McGuire, C. F. 1985. Nutritional quality of barley. In: Rasmusson, D. C. (ed.), Barley: Agronomy Monograph No. 26. Madison, WI: American Society of Agronomy, Crop Science Society of America, Soil Science Society of America, 403–456. Newman, C. W., and Newman, R. K. 2006. A brief history of barley foods. Cereal Foods World 51(1):4–7. Newman, R. K., and Newman, C. W. 1991. Barley as a food grain. Cereal Foods World 36:800–805. Newman, R. K., and Newman, C. W. 2008. Barley for Food and Health: Science, Technology, and Products. Hoboken, NJ: John Wiley & Sons. Nielsen, M. M., and Hansen, Å. 2008. Rapid high‑performance liquid chromatography determination of tocopherols and tocotrienols in cereals. Cereal Chemistry 85:248–251. Osborne, T. B. 1924. Te Vegetable Proteins. New York: Longmans Green and Co. Panfli, G., Fratianni, A., and Irano, M. 2003. Normal phase high‑performance liquid chromatography method for the determination of tocopherols and tocotrienols in cereals. Journal of Agricultural and Food Chemistry 51:3940–3944. Peterson, D. M. 1994. Barley tocols – Efects of milling, malting, and mashing. Cereal Chemistry 71:42–44. Pomeranz, Y., and Shands, H. L. 1974. Food uses of barley. Critical Reviews in Food Science and Nutrition 4(3):377–394. Price, P. B., and Parsons, J. 1979. Distribution of lipids in embryonic axis, bran‑endosperm, and hull fractions of hulless barley and hulless oat grain. Journal of Agricultural and Food Chemistry 27:813–815. Price, P. B., and Parsons, J. G. 1975. Lipids of seven cereal grains. Journal of the American Oil Chemists Society 52:490–493.

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Punia, S., and Sandhu, K. S. 2015. Functional and antioxidant properties of diferent milling fractions of Indian barley cultivars. Carpathian Journal of Food Science and Technology 7(4):19–27. Quinde, Z., Ullrich, S. E., and Baik, B.‑K. 2004. Genotypic variation in color and discoloration potential of barley‑based food products. Cereal Chemistry 81(6):752–758. Raboy, V. 1990. Biochemistry and genetics of phytic acid synthesis. In: Morré, D. J., Boss, W.F., and Loweus, F.A. (eds.), Inositol Metabolism in Plants. New York: Wiley‑Liss, 55–76. Ross, A. B., Shepherd, M. J., Schüpphaus, M., Sinclair, V., Alfaro, B., Kamal‑Eldin, A., and Åman, P. 2003. Alkylresorcinols in cereals and cereal products. Journal of Agricultural and Food Chemistry 51(14):4111–4118. Stanca, A. M., Gianinetti, A., Rizza, F., and Terzi, V. 2016. Barley: An overview of a versatile cereal grain with many food and feed uses. In: Wrigley, C. W., Corke, H., Seetharaman, K., and Faubion, J. (eds.), Encyclopedia of Food Grains. 2nd ed. Oxford: Elsevier, 147–152. Sun, D. F., and Gong, X. 2009. Barley germplasm and utilization. In: G. Zhang, Guoping, C. Li, Genetics and Improvement of Barley Malt Quality. Berlin/Heidelberg: Springer, 18–62. Tamagawa, K., Iizuka, A., Ikeda, A., Koike, H., Naganuma K., and Komiyama, Y. 1999. Antioxidative activity of proanthocyanidins isolated from barley bran. Te Japanese Society of Food Science and Technology 46:106–110. Tashi, N. 2005. Food preparation from hull‑less barley in Tibet. In: Yirga, C., Alemayehu, F., Sinebo, W., and Ethiopian Agricultural Research Organisation (eds.), Barley-Based Farming Systems in the Highlands of Ethiopia. Addis Ababa: Ethiopian Agricultural Research Organization, 115–120. Ullrich, S. E. 2002. Genetics and breeding of barley feed quality. In: Slafer, G. A., Molina‑Cano, J. L., Savin, R. Araus, J. L., and Romagosa, I. (eds.), Barley Science: Recent Advances from Molecular Biology to Agronomy of Yield and Quality. Binghamton, NY: Haworth Press, 115–142. Ullrich, S. E. 2014. Te barley crop: Origin and taxonomy, production, and end uses. In: P. R. Shewry and S. E. Ullrich, Barley: Chemistry and Technology. UK: Woodhead Publishing and AACC International Press, 1–9. Vasanthan, T., and Hoover, R. 2009. Barley starch: Production, properties, modifcation and uses. In: J. BeMiller, R. Whistler, Starch. Burlington, VT: Academic Press, 601–628. Wang, C. P., Pan, Z. F., Nima, Z. X., Tang, Y. W., Cai, P., Liang, J. J., Deng, G. B., and Yu, M. Q. 2011. Starch granule‑associated proteins of hull‑less barley (Hordeum vulgare L.) from the Qinghai‑ Tibet Plateau in China. Journal of the Science of Food and Agriculture 91(4):616–624.

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Ward, J. L., Poutanen, K., Gebruers, K., Piironen, V., Lampi, A. M., Nyström, L., Andersson, A. A., Aman, P., Boros, D., Rakszegi, M., Bedo, Z., and Shewry, P. R. 2008. Te HEALTHGRAIN cereal diversity screen: Concept, results, and prospects. Journal of Agricultural and Food Chemistry 56:9699–9709. Welch, R. W. 1978. Genotypic variation in oil and protei n in barley grain. Journal of the Science of Food and Agriculture 29:953–958. Xue, Q., Wang, L., Newman, R. K., Newman, C. W., and Graham, H. 1997. Infuence of the hulless, waxy starch and short‑awn genes on the composition of barleys. Journal of Cereal Science 26:251–257. Yalçın, E., Çelik, S., and İbanoğlu, E. 2008. Foaming properties of barley protein isolates and hydrolysates. European Food Research and Technology 226:967–974. Zheng, X. L., Li, L. M., and Wang, Q. 2012. Te properties of β‑glucans from diferent fractions of hull‑less barley. Advanced Materials Research 365:338–341. Zhou, M. 2010. Barley production and consumption. In: Zhang, G., and Li, C. (eds.), Genetics and Improvement of Barley Malt Quality. Hangzhou: Zhejiang University Press; Berlin/Heidelberg: Springer. Zieliński, H., and Kozłowska, H. 2000. Antioxidant activity and total phenolics in selected cereal grains and their diferent morphological fractions. Journal of Agricultural and Food Chemistry 48:2008–2016. Zohary, D., and Hopf, M. 2000. Domestication of Plants in the Old World: Te Origin and Spread of Cultivated Plants in West Asia, Europe and the Nile Valley. 3rd ed. Oxford, UK: Oxford University Press.

2 P HYSI CAL

AND

FUN CTIONAL P ROPERTIES

2.1 Introduction

Physical properties are indicators of the quality of cereal grains. Equipment for the handling, harvesting, processing, and sorting (Davies, 2009), and cleaning, grading, and separation (Baryeh, 2001) is often designed on the basis of these properties. Such properties are important to determine the fow behaviour of four. Grain yields are generally determined by the use of standard tests established for each commodity. Physical properties, i.e., geometric mean diameter, arithmetic mean diameter, sphericity, surface area, bulk density, true density, porosity, angle of repose, etc. play an important role during equipment design, and handling and processing of grains. Functional properties (water absorption capacity, oil absorption capacity, foaming capacity and stability, emulsion capacity and stability) play an important role in the manufacturing of products and afect the sensory characteristics of foods. 2.2 Physical Properties

Tousand kernel weight is determined by weighing 1000 randomly selected grains in an electronic balance reading to 0.001 g (Aviara et al., 2013). It provides guidance on the grain size distribution and milling yield (Godon and Wilhm, 1994) and is generally infuenced by grain dimensions (length, breadth, and diameter) (Aprodu and Banu, 2017). Tousand kernel weight for barley was found in the range of 27–46 g (Aprodu and Banu, 2017; Punia and Sandhu, 2015; Bhatty and Rossnagel, 1998).

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Te grain dimensions length (L), width (W), and thickness (T) are measured using a handheld digital caliper. l/b ratio is in the range of 3.2–3.5 for barley cultivars (Punia and Sandhu, 2015). Hamdani et al. (2014) calculated L, W, and T of 8.569 mm, 3.683 mm, and 2.643 mm for hulled barley and 9.485 mm, 3.764 mm, and 2.85 mm for hull‑less barley. Tese dimensions are used to calculate grain geometric mean diameter, arithmetic mean diameter, sphericity, etc. Te geometric mean of dimension (Dg) provides an indication of the seeds’ behavioural patterns in a fowing fuid (Hamdani et al., 2014) and is determined by Equation (2.1) (Mohsenin, 1980; Song and Litchfeld, 1991) as Dg = ( L ´ W ´ thickness )

1/3

(2.1)

Te geometric mean diameter ranged from 4.34 to 4.51 mm for barley varieties (Gürsoy and Güzel, 2010). Hamdani et al. (2014) reported geometric mean diameters of 4.33 and 4.53 mm for hulled barley and hull‑less barley. Te arithmetic mean diameter (Da) is determined according to the formula given by Mohsenin (1980) as: Da = ( L ´ W ´ T ) / 3

(2.2)

and Hamdani et al. (2014) reported an arithmetic mean diameter of 4.331 and 4.538 mm for hulled barley and hull‑less barley. Sphericity is calculated as the cube root of L × W × D divided by L (Coşkuner and Karababa, 2007): Sphericity = ( Dg / L ) ´100

(2.3)

Te sphericity values were found to be in the range of 44.4–45.8% for barley varieties (Gürsoy and Güzel, 2010). According to Jain and Bal (1997), seed volume (V, mm3) is calculated using the following formula: 0.5 V = pB2L2 where B = ( WT ) éë6 ( 2L - B ) ùû

(2.4)

Te seed volume was found to be 26.95 mm3 for hulled barley and 31.80 mm3 for hull‑less barley (Hamdani et al., 2014). Te surface area, S (mm 2mm2), is studied to observe the grain behaviour on oscillating surfaces during processing (Hamdani et al.,

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2014) and measured by fusing the formula given by Altuntaş et al. (2005), Tunde‑Akintunde and Akintunde (2004), and Sacilik et al. (2003) as: S = D2 g × p

(2.5)

Hamdani et al. (2014) examined the surface areas of 58.46 mm2 and 65.65 mm2, respectively, for hulled and hull‑less barley. True density is the density of the solid material excluding the volume of any open pores and closed pores. Bulk density is a characteristic of a volume of divided material such as powders, grains, and granules. It includes the volume of the solid material, open and closed pores, and the interparticle voids. Te true and bulk density play a signifcant role in drying, design of silos and storage bins, separation of undesirable materials, seed purity determination, and grading (Mohsenin, 1980). Seed densities have been determined by water displacement in studies on the swelling of seeds following imbibition of water (Leopold, 1983). Bulk density is measured by dividing the weight/mass of seeds by their volume using a measuring cylinder (AOAC, 1980) and is used to determine the capacity of storage and transport, while the true density is useful to design proper separation equipment (Brooker et al., 1992; Kachru et al., 1994). Punia and Sandhu (2015) reported bulk density in the range of 0.567–0.643 g/ml for barley cultivars. Moreover, the porosity of the grain mass determines the resistance to airfow during the aeration and drying operation (Brooker et al., 1992; Kachru et al., 1994). Te porosity is determined as a function of the bulk density and kernel density of the grain (Nelson, 2002). Hamdani et al. (2014) reported 37.95% porosity for hulled barley and 67.24% for hull‑less barley. Te angle of repose is the angle compared to the horizontal at which the material will stand when piled (Hamdani et al., 2014). Te value of the angle of repose is found to be 50.44° and 63.45° for hulled and hull‑less barley, respectively. Te results of the measurements are summarized in Table 2.1 for barley grain and seed. 2.3 Milling

Te traditional food processing of barley produces pot and pearled barley, fakes, and four (Aprodu and Banu, 2017). Te objective of

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Table 2.1

Characteristics of Barley

L/B ratio Bulk density True density Thousand kernel weight

Porosity Length Width Thickness Geometric mean diameter

Arithmetic mean diameter Sphericity L*

a*

b*

∆E Water absorption capacity (WAC) Oil absorption capacity (OAC) Foaming capacity (FC) Foaming stability (FS) Peak viscosity (PV)

3.2–3.5 (Punia and Sandhu, 2015) 0.567–0.643 g/ml (Punia and Sandhu, 2015) 0.530–0.690 g/ml (Hamdani et al., 2014) 1.112–1.333 g/ml) (Hamdani et al., 2014) 38.0 g (Aprodu and Banu, 2017) 41.2–46.6 g (Punia and Sandhu, 2015) 27–40 g (Bhatty and Rossnagel, 1998) 37.95% (hulled barley) 60.24% (hull-less barley) (Hamdani et al., 2014) 6.36 mm (Aprodu and Banu, 2017) 7.37 mm (Kaliniewicz et al., 2015) 3.52 mm (Aprodu and Banu, 2017) 2.92 mm (Kaliniewicz et al., 2015) 2.71 mm (Aprodu and Banu, 2017) 2.11 mm (Kaliniewicz et al., 2015) 4.33 (hulled barley) (Hamdani et al., 2014) 4.53 (hull-less barley (Hamdani et al., 2014) 4.34–4.51 (Gürsoy and Güzel, 2010) 4.331 (hulled barley) (Hamdani et al., 2014) 4.538 (hull-less barley (Hamdani et al., 2014) 44.4–45.8% (Gürsoy and Güzel, 2010) 89.2–92.7 (Punia and Sandhu, 2015) 88.6–89.5 (Sharma and Gujral, 2010) 66.6–81.1 (Bellido and Beta, 2009) 0.59–1.38 (Punia and Sandhu, 2015) 0.7–0.9 (Sharma and Gujral, 2010) 1.4–1.9 (Bellido and Beta, 2009) 7.75–11.52 (Punia and Sandhu, 2015) 7.6–8.7 (Sharma and Gujral, 2010) 8.8–13.9 (Bellido and Beta, 2009) 89.9–93.1 (Punia and Sandhu, 2015) 88.9–90 (Sharma and Gujral, 2010) 181–224% (Punia and Sandhu, 2015) 1.38–1.63 g/g (Sharma and Gujral, 2010) 176–192% (Punia and Sandhu, 2015) 1.5–1.68 g/g (Sharma and Gujral, 2010) 117 ml (Mohamed et al., 2007) 70.5% (Mohamed et al., 2007) 4858–5545 cP (Fan et al., 2019) 381–3751 cP (Gray et al., 2010) 3775 cP (Sullivan et al., 2010) 3604 cP (Köksel et al., 2004) (Continued )

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Table 2.1 (Continued)

25

Characteristics of Barley

Breakdown viscosity (BV)

Trough viscosity (TV) Final viscosity (FV)

Pasting temperature (PT) Enthalpy of gelatinization (∆ Hgel) Onset temperature (To) Peak temperature (Tp)

1406–1938 cP (Fan et al., 2019) 282–2470 (Gray et al., 2010) 1570 cP (Sullivan et al., 2010) 2890–4139 cP (Fan et al., 2019) 1682 cP (Köksel et al., 2004) 4629–5820 cP (Fan et al., 2019) 233–4765 cP (Gray et al., 2010) 2490 cP (Sullivan et al., 2010) 3411 cP (Köksel et al., 2004) 71.2–73.4°C (Fan et al., 2019) 4.45–7.08 J/g (Sharma and Gujral, 2010) 2.9–9.6 J/g (Symons and Brennan, 2004a) 60–64°C (Symons and Brennan, 2004a) 64.2–72.6°C (Symons and Brennan, 2004a) 68.5°C (Symons and Brennan, 2004b)

milling is to remove indigestible hull/husk from barley grain and convert it into fakes or four (Flow chart 2.2). Te milling process of barley is done in two steps: (1) pearling and (2) milling. After cleaning the barley grains with magnets (to remove ferrous metals), aspirators (to remove dust and chaf), separators (to remove impurities larger Barley grains Cleaning Conditioning Aspiration (removal of hulls) De-hulled barley Pearling Pearled barley Roller milling Flour

Flow Chart 2.2

Milling of barley.

pre-damping cooking (by steam) flaking Hot air drying flakes

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than the grain), destoners (to remove stones of the same size), and scourers and disk separators (to remove foreign particles that adhere to the grain) (Izydorczyk and Dexter, 2016), pearling is done. In locations where it is permitted, certain varieties of barley with blue‑pigmented aleurone may be bleached (Ram and Misra, 2010). Pearling is a process of abrasion which removes the outer layer of grains by using a pearler (Figure 2.1). A pearler consists of stones revolving within a perforated cylinder, and the hulls are gradually rubbed against the stones. Te feeding rate, stone roughness, and distance between the stones determine the pearling rate. Pealing produces pot or blocked (hulls are removed) barley and pearled barley. Te barley from which the fewest pearlings have been removed (5%) may be referred to as blocked, pot, or Scotch barley; however, pearl barley is usually understood to be barley from which about 11% or more of the original grain has been abraded (Rosentrater and Evers, 2018). Initial 10% pearling removes hulls; 15% eliminates pericarp, testa, and some layers of aleurone; and 30% results in the complete removal of outer tissues (Izydorczyk and Dexter, 2016). As many outer layers are removed during pearling, the grain composition is changed. Pearled barley contains endosperms enriched in starch and β‑glucans

Figure 2.1

Pearler.

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and proteins. Pot and pearl barley are used directly in various food recipes or may be subjected to such processes as milling, grinding, or faking, before incorporation into food products. Milling is an important and intermediate step in the postproduction of grain and transformation of raw materials into fner primary products for secondary processing (Bender, 2006). Cereals are milled by grinding the grains in roller, hammer, disk, or stone. With the grinding process, compression, impact, or shear force is applied to reduce the particle sizes. Diferent types of milling machines afect the physical, chemical, nutritional, and functional properties of the milled products (Aprodu and Banu, 2017). After applying certain adjustments with respect to the parameters used for wheat roller milling, hulled barley can be subjected to roller milling (Moza and Gujral, 2017). Barley four is milled from pearled, blocked, or hull‑less barley. Optimum tempering conditions are 13% moisture content (m.c.) for 48 hours for pearl barley and 14% m.c. for 48 hours for unpearled, hull‑less grain. Te milling system uses roller mills with futed and smooth rolls and plansifters, in much the same way as in wheat four milling. Barley four is also a by‑product of pearling and polishing processes (Rosentrater and Evers, 2018). According to Izydorczyk and Dexter (2016), β‑glucans, dietary fber, and phenolic compounds are associated with the cell walls of grains and during milling remain concentrated in the coarse milling fractions; therefore, roller milling processes nowadays focus on producing glucan/dietary fber‑enriched fractions to retain these potential and/or improved benefts in these milled products. To make barley fakes, barley groats or pearl barley are subjected to damping, steam cooking, and faking – using large‑ diameter faking rolls or by drying on a hot‑air dryer. 2.4 Hunter Color Characteristics

Colour is an important sensory characteristic and is used to judge the quality and acceptance of food or products (Clydesdale, 1993). Hunter colour parameters of cereal grains are evaluated using the hunter colour lab. Varietal diferences are observed for various colour parameters of barley. Te L* value indicates the lightness, with 0–100 representing dark to light, and the values ranging from 89.2 to 92.7. Te

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a* value, which indicates the degree of the red‑green colour, ranged from 0.59 to 1.38, and the b* value, which indicates the degree of the yellow‑blue colour, ranged from 7.75 to 11.52. Te total colour diference (ΔE) was signifcantly afected among diferent barley cultivars and ranged from 89.9 to 93.1 (Punia and Sandhu, 2015). Sharma and Gujral (2010) reported L*, a*, b*, and ΔE ranging from 88.6 to 89.5, 0.7 to 0.9, 7.6 to 8.7, and 88.9 to 90, respectively, for barley cultivars. Bellido and Beta (2009) reported L* value ranging from 66.6 to 81.1, a* value 1.4 to 1.9, and b* value 8.8 to 13.9 for diferent barley cultivars. Yeung and Vasanthan (2001) concluded that barley exhibited more lightness and less yellowness and redness, when compared with whole wheat four. Tey reported L*, a*, and b* values that ranged from 87.0 to 87.7, 1.3 to 1.4, and 10.4 to 10.5, respectively, for barley cultivars. Bhatty (1993) reported that the lightness of roller‑milled four ranged from 78.8 to 86.7 for 16 diferent barley cultivars. 2.5 Functional Properties

Water absorption capacity (WAC) and oil absorption capacity (OAC) are important physicochemical properties (Elleuch et al., 2011). Te functional properties of the four of diferent barley cultivars are summarized in Table 2.1. WAC represents the ability of a product to associate with water under conditions where water is limited (Singh, 2001). Te WAC of barley four depends on the presence of β‑glucan and insoluble fber (Bhatty, 1993, 1997) and plays an important role on baking time, shelf life, and textural properties of resulting food products. A higher water‑retention capacity is associated with a lower staling rate of bread and chapatti. Punia and Sandhu (2015) reported WAC in the range of 181–224% for barley cultivars, with cv.BH‑885 and cv.DWR‑52 showing the highest and the lowest values. Bhatty (1997) calculated a WAC of 2.5 ml/g and 1.1 ml/g for waxy (high β‑glucan) and regular (low β‑glucan) barley cultivars. Elleuch et al. (2011) reported higher WAC for barley than wheat. Te OAC of fours is also important as it improves the mouth feel and retains the favour of food products (Kinsella, 1976). Te binding ability of four with oil is useful in food systems where optimum oil holding is required (Akinyede and Amoo, 2009). It is of great importance in various food formulations including ground meat

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and sausages since it refects the emulsifying capacity (Suresh, 2013; Escamilla‑Silva et al., 2003). Te values of OAC ranged from 176% to 192% for six diferent barley cultivars (Punia and Sandhu, 2015). Sharma and Gujral (2010) reported the WAC and OAC in ranges of 1.38–1.63 g/g and 1.5–1.68 g/g, respectively, for barley. Foaming capacity (FC) and foaming stability (FS) are used as indices of the whipping properties of proteins (Mwasaru et al., 1999). Foaming properties are dependent on proteins as well as on other components such as carbohydrates (Ma et al., 2011). FC and FS of fours from diferent barley cultivars difer signifcantly (p < 0.05). Te FC of barley fours ranged from 13.2% to 25.3% for six cultivars. All the barley fours showed high FS (>90%) after 120 minutes of storage, and the values ranged from 66.7% to 81.3%. Since FS is governed by the ability of the flm formed around entrapped air bubbles to remain intact without draining, it follows that stable foams can only be formed by highly surface‑active solutes (Cherry and McWatters, 1981). FS is important since the usefulness of whipping agents depends on their ability to maintain the whip as long as possible (Lin et al., 1974). Mohamed et al. (2007) reported FC and FS of 117 ml and 70.5% for barley four. Emulsifying properties are very important properties as proteins and other amphoteric molecules contribute to the development of traditional or novel foods (Ma et al., 2011). Emulsion capacity (EC) refects the ability and capacity of a protein to aid in the formation of an emulsion and is related to the protein’s ability to absorb into the interfacial area of oil and water in an emulsion. Te emulsion stability (ES) normally refects the ability of the proteins to impart strength to an emulsion for resistance to stress and change and is therefore related to the consistency of the interfacial area over a defned time period (Pearce and Kinsella, 1978). Te EC of fours from diferent cultivars difered signifcantly (p < 0.05) and ranged from 17.6% to 28.3%, the highest and the lowest being observed for cv.BH‑932 and cv.BH‑885, respectively. Te ES of diferent barley fours ranged from 68.1% to 81.8%. Te diference in total protein composition, as well as components other than proteins, may contribute substantially to the emulsifcation properties of protein‑containing products (McWatters and Cherry, 1977).

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2.6 Pasting Properties

Pasting properties refer to the behaviour of viscosity developed during the cooking cycle (from 50°C to 95°C) and refect the capacity of the four to absorb water and swell as the slurry is heated. It is an important parameter in food processing and afects the quality of the products (Gray et al., 2010). Diferent barley cultivars have variation in peak, trough, breakdown, and fnal viscosity. Peak viscosity (PV) is related to the degree of swelling of granules during heating (Ragaee and Abdel, 2006), breakdown viscosity (BV) is the measure of the vulnerability or susceptibility of the of the cooked starch to disintegration, trough viscosity (TV) measures the ability of a paste to withstand breakdown during cooling, and fnal viscosity (FV) measures the stability of a cooked paste. Fan et al. (2019) used Rapid Visco Analyser (RVA) to measure the pasting profle of barley fours and reported PV, TV, BD, FV, and pasting temperature (PT) in the range of 4858–5545 cP, 2890–4139 cP, 1406–1938 cP, 4629–5820 cP, and 71.2–73.4°C, respectively. Gray et al. (2010) and Sullivan et al. (2010) studied the pasting behaviour of diferent whole barley cultivars and reported PV, BV, and FV in the range of 381–3775 cP, 282–2470 cP, and 233–4765 cP, respectively, and Sullivan concluded that the amount of β‑glucan signifcantly afected the pasting profle of barley. Barley four exhibited PV, TV, and FV of 3604 cP, 1682 cP, and 3411 cP at 95°C temperature and 14% moisture content (Köksel et al., 2004). Symonas and Brennen (2004a) reported that pasting properties of fours depend on starch characteristics of the four such as swelling potential, degree of gelatinization, and the subsequent reassociation of amylose and amylopectin after the disruption of granules. 2.7 Termal Properties

Diferential scanning calorimetry (DSC) is an instrument used to measure the gelatinization and thermal properties (onset (To), peak (Tp), and endset (Te) temperatures; enthalpy (∆ Hgel) of gelatinization; peak height index (PHI); and gelatinization range (R)). Termogram (curve generated by DSC) is a curve of temperature versus heat fux and analyzes melting (frst order) and glass transition temperatures (second order) and gives information on order–disorder phenomena of starch

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granules (Karim et al., 2007). Sharma and Gujral (2010) reported ∆ Hgel of 4.45–7.08 J/g for diferent barley cultivars. Symons and Brennan (2004a) concluded that thermal characteristics are infuenced by cultivars and their composition and they reported ∆ Hgel, To, and Tp of 2.9– 9.6 J/g, 60–64°C, and 64.2–72.6°C, and Symons and Brennan (2004b) reported a peak gelatinization temperature of 68.5°C for barley. 2.8 Conclusions

Barley is an important crop, and regular consumption of barley may reduce the risk of coronary heart disease. Various products processed from barley are available in the market and are gaining popularity as functional foods. Te physical behaviour, sensory characteristics, and end quality of food products are associated with physical, physicochemical, and functional properties of barley. Te changes occurring in these parameters during food processing and their role in product development must be studied and applied to ensure better food products from barley.

References

Akinyede, A. I., and Amoo, I. A. 2009. Chemical and functional properties of full fat and defatted Cassia fstula seed fours. Pakistan Journal of Nutrition 8:765–769. Altuntaş, E., Özgöz, E., and Taşer, Ö. F. 2005. Some physical properties of fenugreek (Trigonella foenum-graceum L.) seeds. Journal of Food Engineering 71(1):37–43. AOAC. 1980. Ofcial Methods of Analysis. 13th ed. Washington, DC: Association of Ofcial Analytical Chemists. Aprodu, I., and Banu, I. 2017. Milling, functional and thermo‑mechanical properties of wheat, rye, triticale, barley and oat. Journal of Cereal Science 77:42–48. Aviara, N. A., Power, P. P., and Abbas, T. 2013. Moisture‑dependent physical properties of Moringa oleifera seed relevant in bulk handling and mechanical processing. Industrial Crops and Products 42:96–104. Baryeh, E. A. 2001. Physical properties of bambara groundnuts. Journal of Food Engineering 47(4):321–326. Bellido, G. G., and Beta, T. 2009. Anthocyanin composition and oxygen radical scavenging capacity (ORAC) of milled and pearled purple, black, and common barley. Journal of Agricultural and Food Chemistry 57:1022–1028.

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Bender, D. A. 2006. Benders Dictionary of Nutrition and Food Technology. 8th ed. Abington: Woodhead Publishing/CRC Press. Bhatty, R. S. 1993. Physicochemical properties of roller milled barley four and bran. Cereal Chemistry 70:397–402. Bhatty, R. S. 1997. Milling of regular and waxy starch hull‑less barleys for the production of bran and four. Cereal Chemistry 74:693–699. Bhatty, R. S., and Rossnagel, B. G. 1998. Comparison of pearled and unpearled Canadian and Japanese barleys. Cereal Chemistry 75:15–21. Brooker, D. B., Bakker‑Arkema, F., and Hall, C. W. 1992. Drying and Storage of Grains and Oilseeds. Springer, NY: Van Nostrand Reinhold. Cherry, J. P., and McWatters, K. H. 1981. Whippability and aeration. In: Cherry, J. P. (eds.), Protein Functionality in Foods, ACS Symposium Series 147. Washington, DC: American Chemical Society, 149. Clydesdale, F. M. 1993. Color as a factor in food choice. Critical Reviews in Food Science and Nutrition 33(1):83–101. Coşkuner, Y., and Karababa, E. 2007. Physical properties of coriander seeds (Coriandrum sativum L.). Journal of Food Engineering 80:408–416. Davies, R. M. 2009. Some physical properties of groundnut grains. Research Journal of Applied Sciences, Engineering and Technology 1(2):10–13. Elleuch, M., Bedigian, D., Roiseux, O., Besbes, S., Blecker, C., and Attia, H. 2011. Dietary fbre and fbre‑rich by‑products of food processing: Characterisation, technological functionality and commercial applications: A review. Food Chemistry 124:411–421. Escamilla‑Silva, E. M., Guzmán‑Maldonado, S. H., Cano‑Medinal, A., and González‑Alatorre, G. 2003. Simplifed process for the production of sesame protein concentrate. Diferential scanning calorimetry and nutritional, physicochemical and functional properties. Journal of the Science of Food and Agriculture 83:972–979. Fan, X., Zhu, J., Dong, W., Sun, Y., Lv, C., Guo, B., and Xu, R. 2019. Comparison of pasting properties measured from the whole grain four and extracted starch in barley (Hordeum vulgare L.). PloS one 14(5):e0216978. Godon, B., and Wilhm, C. 1994. Primary Cereal Processing: A Comprehensive Sourcebook. New York: VCH. Gray, D., Abdel‑Aal, E. S. M., Seetharaman, K., and Kakuda, Y. 2010. Diferences in viscosity and textural properties of selected barley cultivars as infuenced by pearling and cooking. Food Chemistry 120:402–409. Gürsoy, S., and Güzel, E. 2010. Determination of physical properties of some agricultural grains. Research Journal of Applied Sciences, Engineering and Technology 2(5):492–498. Hamdani, A., Rather, S. A., Shah, A., Gani, A., Wani, S. M., Masoodi, F. A., and Gani, A. 2014. Physical properties of barley and oats cultivars grown in high altitude Himalayan regions of India. Journal of Food Measurement and Characterization 8(4):296–304. Izydorczyk, M. S., and Dexter, J. E. 2016. Barley: Milling and processing. In: C. Wrigley, H. Corke, K. Seetharaman, J. Faubion, Encyclopedia of Food Grains, 2nd Edition. Oxford: Academic Press, 434–445.

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Jain, R. K., and Bal, S. 1997. Properties of pearl millet. Journal of Agricultural Engineering Research 66(2):85–91. Kachru, R. P., Gupta, R. K., and Alam, A. 1994. Physico-Chemical Constituents and Engineering Properties of Food Crops. 1st ed. Jodhpur, India: Scientifc Publishers. Kaliniewicz, Z., Biedulska, J., and Jadwisieńczak, B. 2015. Assessment of cereal seed shape with the use of sphericity factors. Technical Sciences/ University of Warmia and Mazury in Olsztyn 18(4):237–246. Karim, A., Norziah, M., and Seow, C. 2007. Methods for the study of starch retrogradation. Food Chemistry 71:9–36. Kinsella, J. E. 1976. Functional properties of proteins in foods: A survey. Critical Reviews in Food Science and Nutrition 7:219–280. Köksel, H., Ryu, G. H., Başman, A., Demiralp, H., and Ng, P. K. W. 2004. Efects of extrusion variables on the properties of waxy hull‑less barley extrudates. Nahrung/Food 48:19–24. Leopold, A. C. 1983. Volumetric components of seed imbibition. Plant Physiology 73:677–680. Lin, M. J. Y., Humbert, E. S., and Sosulski, F. W. 1974. Certain functional properties of sunfower meal products. Journal of Food Science 39:368–370. Ma, Z., Boye, J. I., Simpson, B. K., Prasher, S. O., Monpetit, D., and Malcolmson, L. 2011. Termal processing efects on the functional properties and microstructure of lentil, chickpea, and pea fours. Food Research International 44:2534–2544. McWatters, K. H., and Cherry, J. P. 1977. Emulsifcation, foaming and protein solubility properties of defatted soybean, peanut, feldpea and pecan fours. Journal of Food Science 42:1444–1447. Mohamed, A., Hojilla‑Evangelista, M. P., Peterson, S. C., and Biresaw, G. 2007. Barley protein isolate: Termal, functional, rheological, and surface properties. Journal of the American Oil Chemists’ Society 84:281–288. Mohsenin, N. N. 1980. Physical Properties of Plant and Animal Materials. New York: Gordon and Breach Science Publishers. Moza, J., and Gujral, H. S. 2017. Infuence of non‑starchy polysaccharides on barley milling behavior and evaluating bioactive composition of milled fractions. Food Chemistry 218:137–143. Mwasaru, A. M., Muhammad, K., Bakar, J., and Cheman, Y. B. 1999. Efect of isolation technique and conditions on the extractability, physiochemical and functional properties of pigeon pea (Cajanus cajan) and cow pea (Vigna unguiculata) protein isolates. II. Functional properties. Food Chemistry 67:435–443. Nelson, S. O. 2002. Dimensional and density data for seeds of cereal grain and other crops. Transactions of the ASAE 45(1):165. Pearce, K. N., and Kinsella, J. E. 1978. Emulsifying properties of proteins: Evaluation of a turbidimetric technique. Journal of Agricultural and Food Chemistry 26:716–723.

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Punia, S., and Sandhu, K. S. 2015. Functional and antioxidant properties of diferent milling fractions of Indian barley cultivars. Carpathian Journal of Food Science and Technology 7(4):19–27. Ragaee, S., and Abdel‑Aal, E. S. M. 2006. Pasting properties of starch and protein in selected cereals and quality of their food products. Food Chemistry 95(1):9–18. Ram, S., and Misra, B. 2010. Cereals, Processing, and Nutritional Quality. New Delhi, India: New India Publishing Agency. Rosentrater, K. A., and Evers, A. D. 2018. Dry‑milling technology. In: Kent's Technology of Cereals. 5th ed. Duxford, UK: Woodhead Publishing Series in Food Science, Technology and Nutrition, 421–514. Sacilik, K., Öztürk, R., and Keskin, R. 2003. Some physical properties of hemp seed. Biosystems Engineering 86(2):191–198. Sharma, P., and Gujral, H. S. 2010. Milling behavior of hulled barley and its thermal and pasting properties. Journal of Food Engineering 97:329–334. Singh, U. 2001. Functional properties of grain legume fours. Journal of Food Science and Technology 38:191–199. Song, H., and Litchfeld, J. B. 1991. Predicting method of terminal velocity for grains. Transactions of the ASAE 34(1):225–231. Sullivan, P., O’Flaherty, J., Brunton, N., Gee, V. L., Arendt, E., and Gallagher, E. 2010. Chemical composition and microstructure of milled barley fractions. European Food Research and Technology 230:579–595. Suresh, C. 2013. Assessment of functional properties of diferent fours. African Journal of Agricultural Research 8(38):4849–4852. Symons, L. J., and Brennan, C. S. 2004a. Te efect of barley β‑glucan fbre fractions on starch gelatinisation and pasting characteristics. Journal of Food Science 69(4):FCT257–FCT261. Symons, L. J., and Brennan, C. S. 2004b. Te infuence of (1→3) (1→4)‑β‑D‑ glucan rich fractions from barley on the physicochemical properties and in vitro reducing sugar release of white wheat breads. Journal of Food Science 69(6):C463–C467. Tunde‑Akintunde, T. Y., and Akintunde, B. O. 2004. Some physical properties of sesame seed. Biosystems Engineering 88(1):127–129. Yeung, J., and Vasanthan, T. 2001. Pearling of hull‑less barley: Product composition and gel color of pearled barley fours as afected by the degree of pearling. Journal of Agricultural and Food Chemistry 49:331–335.

3 FUN CTI ONAL C OMP ONENTS AND A NTIOXIDANT P OTENTIAL OF B ARLE Y

3.1 Introduction

Cereals are considered as an edible seed of the grass family, Gramineae (Bender and Bender, 1999), and are diferentiated according to their genus. Tey are mainly grown for their nutritious edible seeds, i.e. grains. A number of cereals are grown worldwide which include wheat, rice, corn, oats, barley, and sorghum. Tey are a rich source of carbohydrates, proteins, fats, vitamins, and minerals. Cereals also provide dietary fbres and bioactive compounds (Madhujith and Shahidi, 2007). Bioactive compounds are extranutritional constituents (Kris‑ Etherton et al., 2002) and are referred to as phytochemicals (Hill and Path, 1998) which include phenolic acids, favonoids, carotenoids, tocols, fbres, lignans, tannins, alkylresorcinols, and avenanthramides. Simple phenolic acids and favonoids are the most common phenolic compounds with potent antioxidant properties. Tocols maintain a healthy cardiovascular system (Colombo, 2010). Alkylresorcinols and avenanthramides have antibacterial, anti‑infammatory, and antioxidative properties (Tsuge et al.,1992; Emmons et al., 1999; Bratt et al., 2003; Liu et al., 2004). It has been suggested that the health benefts of bioactive compounds are not attributed to any single compound, but they are due to the combined efects of phenolic and other bioactive components present in grains (Fardet, 2010). Wheat and barley may serve as an excellent source of phenolic acids and favonoids for disease prevention and health promotion. Oats and barley possess cholesterol‑lowering and hypoglycemic efects due to the presence of dietary fbres, namely, β‑glucan (Anderson et al., 1991; Aman, 2006). Rice phytochemicals include tocols and oryzanols (Hall, 2001, 35

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2003). Corn mainly contains tocopherols and tocotreinols (Kurilich and Juvik, 1999; Moreau and Hicks, 2006), phytosterols (Moreau et al., 2001, 2003; Winkler et al., 2007), and carotenoids (Kurilich and Juvik, 1999; Moros et al., 2002). 3.2 Health Benefts of Whole-Grain Cereals

Whole grains, rich in dietary fbres and bioactive compounds, are among the healthiest foods as they provide health benefts (Andreasen et al., 2001) and more bioactive compounds than fruits (Jonesen et al., 2004). Whole‑grain cereal consumption has been associated with reduced incidence of chronic diseases such as cancer (Slavin, 2004), cardiovascular diseases (Mellen et al., 2008; Lutsey et al., 2007), high blood pressure (Behall et al., 2006; Flint et al., 2009), diabetes, and other metabolic diseases (Lutsey et al., 2007; Rave et al., 2007; Qi and Hu, 2007). Te health benefts of whole grains have been partly attributed to a wide variety of antioxidants such as phenolic compounds and favonoids (Rui Hai Liu, 2007; Truswell, 2002). Moreover, many natural bioactive compounds are also present, which exhibit a wide range of biological efects, including antiviral, antiageing, antibacterial, anti‑infammatory, antithrombotic, anticarcinogenicity, and antiallergic properties (Cook and Sammans, 1996; Halliwell et al., 1995). Whole‑grain bioactive compounds may serve as free radical scavengers (Spiller, 2002). Increased consumption of whole‑grain products has been recommended, and cereal products should be the main part of the diet (Richardson, 2003). 3.3 Mechanism of Action

Most of the harmful efects of oxygen are due to the formation of chemical compounds, which have a tendency to transfer oxygen to other substances (Halliwell et al., 1995). Reactive oxygen species (ROS), such as superoxide anion, hydroxyl radical, hydrogen peroxide, and lipid peroxide, are generated in living organisms (Fridovich, 1978). Such reactive species have a surplus of one or more free‑foating electrons and are therefore unstable and highly reactive (Bagchi and Puri, 1998). Tese metabolites are highly reactive and react with proteins, amines, and deoxyribonucleic acid, and in the case of their excess generation, they

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may cause cell death (Kehrer, 1993). A number of reactive species may be formed in the human body and the food system, and these harmful efects result in carcinogenesis, ageing, and atherosclerosis (Yagi, 1987). Terefore, the prevention of oxidation damage caused by ROS and reactive nitrogen species (RNS) has important implications for the prevention and treatment of diseases caused by them. Tese ROS can be combated with the involvement of antioxidants. Te mechanism of action of antioxidants is dependent on the mechanism of chemical oxidation. Oxidation is the removal of an electron (e) from an atom or molecule. Tis is paired with a reduction reaction in which the electrons are added to another molecule. In food systems, oxidation reactions may initiate a free radical chain reaction. 1. R:H + O::O + Initiator → R•+ HOO • 2. R• + O::O→ROO • 3. ROO • + R:H→ROOH + R• 4. RO:OH→RO • + HO • 5. R::R + • OH→R:R‑O • 6. R• + R• →R:R 7. R• + ROO •→ROOR 8. ROO • + ROO • →ROOR + O2 When a hydrogen atom (H•) is removed from an unsaturated fatty acid (R:H) alkyl radical (R•) is formed and oxidation of lipid is initiated (reaction no. 1). Generation of this lipid radical is unfavourable and initiated by the presence of other radical compounds (R•), singlet‑state oxygen (O2), decomposition of hydroperoxides (ROOH), or pigments that act as photosensitizers. In order to stabilize, the alkyl radical (R•) usually undergoes a shift from the cis to trans position and results in the production of a conjugated diene system. Te R can react with O2 to form a peroxyl radical of high energy (ROO •; reaction no. 2). Te peroxyl radical can then remove a hydrogen atom (H) from another unsaturated fatty acid (reaction no. 3) forming hydroperoxide (ROOH) and a new, free alkyl radical (R•). Tis process then generates another fatty acid (reaction no. 4; Srinivasan et al., 2008). Te primary product of lipid oxidation is ROOH. Tey are tasteless and odourless; however, in the presence of metal ions, heat, and light, they decompose to compounds which contribute of‑odours

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and tastes. Alkoxy radicals (RO •) may continue the chain reaction by abstracting H from unsaturated fatty acids (reaction no. 5; Decker, 2002; Srinivasan et al., 2008). Hydroxyl radicals (OH•) may continue the oxidation process by reacting with conjugated systems. Tis chain reaction terminates when two radical species combine to form a nonradical species (reaction no. 6). Antioxidants inhibit the reaction by donating H to radicals (reaction no. 7). Te antioxidant free radical then forms a stable peroxy‑antioxidant compound (reaction no. 8). 3.4 Classifcation of Bioactive Compounds 3.4.1 Phenolic Acids

(a) Hydroxybenzoic Derivatives p‑Hydroxybenzoic acid, cafeic acid, vannilic acid, syringic acid, gallic acid, salicylic acid, and protocatechuic acid. (b) Hydroxycinnamic Derivatives Cinnamic acid, o‑coumaric acid, m‑coumaric acid, p‑coumaric acid, ferulic acid, cafeic acid, and sinapic acid. 3.4.2 Flavonoids

Flavons, isofavones, favonols, favanols, favanones, anthocyanidins, anthocyanins, favononols, and chalcones. 3.4.3 Tocopherols and Tocotrienols

α, β, γ, δ Tocopherols and α, β, γ, δ tocotrienols. 3.4.4 Others

Carotenoids Tannins Lignans Alkylresorcinols Avenanthramides Phytosterols β ‑glucan

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3.5 Bioactive Compounds in Whole-Grain Cereals

Whole‑grain cereals contain unique phytochemicals that complement those in fruits and vegetables when consumed together. Te major plant bioactive compounds in whole‑grain cereals are phenolic compounds, tocols, dietary fbres (mainly β‑glucan), phytic acid, ferulic acid, phytosterols, lignans, γ‑oryzanols, alkylresorcinols, avenanthramides, cinnamic acid, inositols, and betaine (Naczk and Shahidi, 2004; Adom et al., 2003; Zieliński and Kozłowska, 2000). Some bioactive compounds are quite specifc to certain cereals: γ‑oryzanol in rice, β‑glucans in oats and barley, avenanthramide and saponins in oats, and alkylresorcinol in rye, although these are also present in other cereals but relatively in fewer amounts. Te concentrations of bioactive compounds in whole grains are afected by the type of grain, varieties, and the part of the grain (Adom and Liu, 2002; Adom et al., 2003, 2005). 3.6 Phenolic Acids

A phenolic compound is characterized by the compound containing a benzene ring with one or more hydroxyl groups (Chirinos et al., 2009). Tese compounds are universally distributed in the plant kingdom as secondary metabolic products (Martínez‑Valverde et al., 2000) and regarded as a major group of compounds that contribute to the antioxidant activity of cereals (Zielinski and Kozlowska, 2000). Phenolic compounds are synthesized in plants partly as a response to pathogen attack, wounding, and UV radiation (Zulak et al., 2006) and have free radical scavenging capacities and potent antioxidant properties (Shadidi et al., 1992). Simple phenolic acids are the most common phenolic compounds, and they generally occur as soluble conjugated (glycosides) and insoluble forms (Liu, 2007; Nardini and Ghiselli, 2004). Phenolic acids are derivatives of benzoic (Figure 3.1a) and cinnamic acids (Figure 3.1b) and are present in all cereals. Tere are two classes of phenolic acids: hydroxybenzoic acids and hydroxycinnamic acids. Hydroxybenzoic acids include gallic, hydroxybenzoic, salicylic, vanillic, syringic, and protocatechuic acid. Hydroxybenzoic acids are components of hydrolyzable tannins. Te

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R1 OH OCH3 OCH3 H H Protocatechuic acid OH

Benzoic acid Gallic acid Vanillic acid Syringic acid Salicylic acid p-hydroxybenzoic

R2 OH OH OH H OH OH

R3 OH H OCH3 H H H

R4 H H H OH H H

Figure 3.1 Phenolic compounds in cereals: (a) Benzoic acid.

Cinnamic acid Ferulic acid o-Coumaric m -Coumaric p-Coumaric Ceramic acid Sinapic acid Caffeic acid

R1 H OH H H H H H

R2 OCH3 H OH H H OCH3 OH

R3 OH H H OH H OH OH

R4 H H H H H OCH3 H

Figure 3.1 (b) Cinnamic acid.

hydroxycinnamic acids have a C6–C3 structure and include ferulic, coumaric, cinnamic, sinapic, and cafeic acid (Cliford and Scalbert, 2000). Te most abundant cinnamic acid derivative is ferulic acid followed by p‑coumaric acid, and these are mostly concentrated in the aleurone layer and in the pericarp. Phenolic acids are the major phenyl propanoid components in cereals, and diferent amounts of phenolics are found in diferent fractions of cereals. In cereals, the starchy endosperm contains low levels, whereas the pericarp, aleurone layer, and germ (outer layers of the grain) contain the highest (Andreasen et al.,

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1999). In cereals, phenolic acids exist in both free and bound forms. Te bound phenolic acids, constituting 80–95% of the total amount, are mostly ester‑linked to polysaccharides (cell wall polymers); thus acid or base hydrolysis is required to release them from the cell wall matrix (Vichapong et al., 2010; Holtekjolen et al., 2006; Naczk and Shahidi, 2004). Phenolic acids are concentrated in the cell walls of outer layers (Dykes and Rooney, 2007; Maillard and Berset, 1995), while another report indicated that phenolic acids were mainly present in the aleurone layer and endosperm (Goupy et al., 1999). Te main phenolic acids reported in cereals are ferulic and p‑coumaric acids, and both are associated with cell wall constituents (Naczk and Shahidi, 2004). Humans consume an estimated range of 25 mg to 1 g of phenolic acids on a daily basis from fruits, vegetables, grains, tea, cofee, and spices, among others (Cliford, 1999). Phenolic acids have been linked to chronic disease prevention partly due to the presence of the unsaturated carboxylic group (Pandey and Rizvi, 2009). Barley has a number of bioactive compounds that include phenolic acids (Mattila et al., 2005), favonoids (Tamagawa et al., 1999), tocopherols (Panfli et al., 2003), tannins (Collins, 1986), and alkylresorcinols (Ross et al., 2003). Te total phenolic content (TPC) in barley cultivars is in the range of 2890–3922 µg FAE/g (Sandhu and Punia, 2017), 3070–4439 µg FAE/g (Sharma and Gujral, 2010), and 2.63–4.51 mg of ferulic acid equivalents (FAE)/g (Madhujith and Shahidi, 2009). Barley contains many phenolic acids, which include gallic (Weidner et al., 1999; Zhao et al.,2006), ferulic ( Dvořáková et al., 2008;Quinde‑Axtell and Baik, 2006; Zhao et al., 2006; Hernanz et al., 2001; Weidner et al., 1999; Zupfer et al., 1998), o‑hydroxybenzoic (Weidner et al., 1999), vanillic (Madhujith et al., 2006; Weidner et al., 1999; Zielinski et al., 2001; Zhao et al., 2006; Madhujith et al., 2006), syringic (Weidner et al., 1999; Zielinski et al., 2001; Zhao et al., 2006), protocatechuic acid syringic (Weidner et al., 1999), p‑coumaric (Weidner et al., 1999; Zielinski et al., 2001;Quinde‑Axtell andBaik2006; Madhujith et al., 2006; Dvorakova et al., 2008), cinnamic (Weidner et al., 1999), synaptic (Weidner et al., 1999), and cafeic acids (Weidner et al., 1999; Hernanz et al., 2001; Zhao et al., 2006; Quinde‑Axtell and Baik, 2006). Kim et al. (2007) have found

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17 phenolic acids in 127 lines of coloured (black, blue, and purple) barley. In another study, Yu et al. (2001) investigated phenolic acids of 30 barley varieties (combination of hulled/hull‑less/two‑row/six‑r ow/regular/waxy) using high‑performance liquid chromatography (HPLC), and they reported 7 major phenolic acids including benzoic acid derivatives (phydroxybenzoic, vanillic, and protocatechuic acids) and cinnamic acid derivatives (coumaric, cafeic, ferulic, and chlorogenic acids) in barley varieties. Zhao et al. (2006) identifed nine phenolic compounds including (+)‑catechin, (−)‑epicatechin, syringic, ferulic, protocatechuic, cafeic, vanillic, gallic, and p‑coumaric acids in barley varieties. Te phenolic acid concentration in barley approximately ranges between 4.6 and 23 mg/g for the free form, between 86 and 198 mg/g for the conjugated form, and between 133 and 523 mg/g for the bound form, whereas the total phenolic acid concentration ranges between 604 and 1346 mg/g (Holtekjølen et al., 2006; Abdel‑Aal et al., 2012). Te free forms of the major phenolic acids in barley are ferulic acid (27% of dry matter), vanillic acid (28%), syringic acid (17%), and p‑coumaric acid (22%) (Gamel and Abdel‑Aal, 2012). FA is the most abundant and the main low‑molecular‑weight phenolic acid and accounts for 68% of total phenolic acids in barley. Te total ferulic acid in barley grains ranges between 149 and 413 mg/g (Ward et al., 2008) and 270 mg/g (Andersson et al., 2008). Te average total concentrations of free, conjugated, and bound FA for diferent varieties of barley are approximately 2.7, 33.21, and 235 mg/g, respectively. Te antioxidants present in barley as reported by various workers are shown in Table 3.1. 3.7 Flavonoids

Flavonoids, the largest group of plant phenolics, account for over half of the 8,000 naturally occurring phenolic compounds (Harborne et al., 1999). Te basic structure of a favonoid includes a favan nucleus which consists of two benzene rings combined by a pyran ring (Aherne and O’Brien, 2002). Flavonoids are compounds with a C6‑C3‑C6 skeleton that consists of two aromatic rings joined by a three‑carbon link; they include favanes, favonols, favones, favanols, anthocyanidins,

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Antioxidants Present in Barley

BARLEY Total phenolic content Hydroxybenzoic Gallic acid o-Hydroxybenzoic acid Vanillic acid Syringic acid

2890–3922 µg FAE/g (Sandhu and Punia, 2017), 3070–4439 µg FAE/g (Sharma and Gujral, 2010) 2.63–4.51 mg FAE/g (Madhujith and Shahidi, 2009), 604 and 1346 mg/g (Holtekjølen et al., 2006; Abdel-Aal et al., 2012) 1.87–2.16 µg/g (Zhao et al., 2006), 1.03 µg/g (Irakli et al., 2012) 0.77 µg/g (Irakli et al., 2012) 0.63–0.81 µg/g (Zielinski et al., 2001), 3.33–3.57 µg/g (Zhao et al., 2006), 1.50 µg/g (Irakli et al., 2012) 0.21–0.34 µg/g (Zielinski et al., 2001), 9.97–12.01 µg/g (Zhao et al., 2006), 1.62 µg/g (Irakli et al., 2012) 0.50 µg/g (Irakli et al., 2012)

Protocatechuic acid Hydroxycinnamic Ferulic acid 3.0 µg/g (Irakli et al., 2012), 6.24–11.22 µg/g (Zhao et al., 2006), 147–216 mg/kg (Dvorakova et al., 2008) 149–413 mg/g (Ward et al., 2008), 270 mg/g (Andersson et al., 2008), 0.51 µg/g (Zielinski et al., 2001) 301–567 µg/g (Quinde and Baik, 2006; Hernanz et al., 2001; Zupfer et al., 1998) p-Coumaric acid 0.97 µg/g (Irakli et al., 2012), 0.19–0.31 µg/g (Zielinski et al., 2001), 4–21 µg/g (Quinde-axtell and Baik, 2006), 0.19 µg/g (Zielinski et al., 2001), 13.6–29.7 mg/kg (Dvorakova et al., 2008) Cinnamic acid 0.53 µg/g (Irakli et al., 2012) 1.60 µg/g (Irakli et al., 2012) Sinapic acid 1.01 µg/g (Irakli et al., 2012), 4.81–5.77 µg/g (Zhao et al., 2006), 15–36 Caffeic acid µg/g (Quinde and Baik, 2006), 7–18 µg/g (Hernanz et al., 2001) Vanillic acid 0.63 µg/g (Zielinski et al., 2001) Syringic acid 0.21 µg/g (Zielinski et al., 2001) Tocols 25.1 mg/kg (Goupy et al., 1999), 75 mg/kg ( ; Panfli et al., 2003) Tocopherols 40 mg/kg (Panfli et al., 2003) Tocotreinol Flavonoids Total favonoids 1968–2198 µg FAE/g (Sandhu and Punia, 2017), 1387–2246 µgCE/g content (Sharma and Gujral, 2011), 62.0 and 300.8 mg/g (Kim et al., 2007) Proanthocyanidins Prodelthinidin B3 102 µg/g (Holtekjolen et al., 2006) 90–197 mg/g (Dvorakova et al., 2008) Procyanidin B3 105 µg/g (Holtekjolen et al., 2006) Prodelphindin C2 89.0 µg/g (Holtekjolenet al., 2006) (Continued )

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Table 3.1 (Continued) Antioxidants Present in Barley BARLEY Procyanidin C2 Anthocyanins Total anthocyanin Cyanidin 3-glucoside Delphinidin 3-glucoside Petunidin 3-glucoside Flavanol Catechin

Flavonol Rutin Myricetin Quercetin Kaempherol Carotenoids Tannins Lignans Alkyl resorcinols

53.0 µg/g (Holtekjolen et al., 2006), 5–19 mg/g (Dvorakova et al., 2008) 210–573 µg/g (Bellido and Beta, 2009) 30–99 µg/g (Bellido and Beta, 2009) 1.2 µg/g (Abdel-Aal et al., 2006) 93–104 µg/g (Bellido and Beta, 2009) 20–37 µg/g (Bellido and Beta, 2009) 2.9 µg/g (Bellido and Beta, 2009) 5.2–5.3 mg/kg (Dvorakova et al., 2008); 5.2–5.3 mg/kg (Dvorakova et al., 2008); 42.6–45.9 µg/g (Zhao et al., 2006) 17.7 µg/g (Holtekjolen et al., 2006); 17.7 µg/g (Holtekjolen et al., 2006) 3.2 µg/g (Holtekjolen et al., 2006) 280 µg/g (Holtekjolen et al., 2006) 17.4 µg/g (Holtekjolen et al., 2006) 12.7 µg/g (Holtekjolen et al., 2006) 15 µg/100 g Choi et al., 2007) 0.74 mg/g (Juliano 1985; Collins, 1986) 205 µg/g (Durazzo et al., 2009) 30–50 mg/kg (Garcia et al., 1997; Zarnowskiet al. 2002; Mattila et al., 2005)

-

R1 CH3 CH3 H H

R2 CH3 H CH3 H

Figure 3.1 (c) Tocopherol.

and isofavones (Figures 3.1c through 3.1h). Tey are considered to be the largest group of naturally occurring phenolics and account for 2% of all the carbon photosynthesized by plants (Vijaykumar et al., 2008). Flavonoids are located in the pericarp of the pigmented varieties

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R1 CH3 CH3 H H

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R2 CH3 H CH3 H

Figure 3.1 (d) Tocotreinol.

Figure 3.1 (e) Elavane.

Figure 3.1 (f) Flavonol.

Figure 3.1 (g) Flavones.

Figure 3.1 (h) Flavanols.

of barley, corn, wheat, rye, and other crops (Cook and Sammans, 1966). Common anthocyanins present in cereals are cyanidin, delphinidin, malvidin, pelargonidin, petunidin, and peonidin. Flavonoids show free radical scavenging, strong antioxidant activity, inhibition

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of hydrolytic and oxidative enzymes, and anti‑infammatory action (Zhishen et al., 1999). Flavonoids may exert antioxidative efects as free radical scavengers, hydrogen‑donating compounds, singlet oxygen scavengers, and chelators – properties attributed to the phenolic hydroxyl groups attached to ring structures (Rice‑Evans et al., 1997). Flavonoids are reported to have antioxidant, anticancer, antiallergic, anti‑infammatory, anticarcinogenic, and gastroprotective properties (Harborne and Williams, 2000). Kim et al. (2007) studied the favonoid content of 127 lines of hulled and unhulled coloured barley wherein the total favonoid content (TFC) was found to range from 62.0 to 300.8 mg/g. Sandhu and Punia (2017) and Sharma and Gujral (2011) reported the TFC of barley in the range of 1968–2198 µgCE/g and 1387–2246 µgCE/g. Barley contains various favanols, with major ones including myricetin (280 µg/g), catechin (17.7 µg/g), and procyanidin B3 (105 µg/g) (Holtekjolen et al., 2006). Te proanthocyanidin content in barley studied by Kim et al. (2007) varied between 15.8 and 131.8 µg/g. Proanthocyanidins are found in the testa of the barley grain (Aastrup et al., 1984), and they exist in barley as an oligomeric mixture of prodelphinidins and procyanidins (McMurrough et al., 1992). Tese compounds are involved in the formation of haze in beer (Siebert et al., 1996; McMurrough et al., 1992). In a related study, Dvorakova et al. (2008) examined the proanthocyanidin content of 10 barley varieties (8 malt and 2 hulless barley varieties). From that study, the major proanthocyanidins reported included two proanthocyanidin dimers (prodelphinidin B3 and procyanidin B3) and four proanthocyanidin trimers (procyanidin C2, prodelphinidin C2, and two other prodelphinidin isomers). Prodelphinidin B3 (90–197 µg/g) accounted for the majority of proanthocyanidin present in barley, whereas procyanidin C2 (5–19 µg/g) was reported to be present only in minor quantities (Figure 3.1i through 3.1o). Anthocyanins in barley include cyanidin, cyanidin 3‑glucoside, delphinidin, pelargonidin, pelargonidin glycosides, and petunidin 3‑glucoside (Abdel‑Aal et al., 2006; Mazza and Gao, 2005). Te most common anthocyanin in purple barley is cyanidin 3‑glucosode (214.8 mg/g), followed by peonidin 3‑glucoside and pelargonidin 3‑glucoside. Tese three anthocyanins account for 50–70% of the

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Figure 3.1 (i) Anthocyanindin.

Figure 3.1 (j) Isofavone.

Figure 3.1 (k) Carotenoid.

total anthocyanins reported in barley. Delphinidin 3‑glucoside is usually the most abundant anthocyanin in blue (167.6 mg/g) and black (36.0 mg/g) barley varieties. In general, purple and blue barley (320.5 mg/g) contain higher average concentrations of anthocyanins than black barley (49.0 mg/g) (Bellido and Beta, 2009; Siebenhandl et al., 2007). Yang et al. (2013) investigated the common favonoids in unhulled purple barley, normal barley, and hulled purple barley and concluded that the bran‑rich fraction of barley grain contained the most favonoid content, whereas the hull fraction did not contain

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Figure 3.1 (l) Tannins.

any signifcant favonoid content. Tey reported that the total concentration of catechin in normal barley was in the range of 0–21.85 mg/g and was signifcantly higher than that in hulled purple barley and unhulled purple barley. Whole‑grain myricetin content in hulled purple barley was signifcantly higher than that in unhulled purple barley and normal barley. Te total average content of quercetin in hulled purple barley (60.98 µg/g) was signifcantly higher than that in unhulled purple barley (24.35 µg/g) and normal barley (0.00 µg/g). Te total average kaempferol content in unhulled purple barley (36.00 µg/g) was considerably higher than that in hulled purple barley (32.56 µg/g) and normal barley (26.65 µg/g).

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Figure 3.1 (m) Lignan.

Figure 3.1 (n) Alkylresorcinol.

Figure 3.1 (o) β‑glucan.

3.8 Tocopherols

Tocopherols are considered promising compounds that are able to maintain a healthy cardiovascular system and satisfactory blood cholesterol levels (Colombo, 2010). Vitamin E, i.e. chroman‑6‑ols, collectively tocochromanols (tocopherols (Figure 3.1c) + tocotrienols (Figure 3.1d), is generally consumed along with fat‑containing foods (Zingg, 2007). Te tocochromanol vitamin E homologues with the

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largest difusion in nature are four tocopherols, i.e. α‑, β‑, γ‑, and δ‑tocopherols, and four tocotrienols, α‑, β‑, γ‑, and δ‑tocotrienols. Both tocopherols and tocotrienols have the same basic chemical structure, i.e. at the 2‑position of a chromane ring, a long chain is attached. Tocotrienols difer from tocopherols because they possess a farnesyl group. Either tocopherols or tocotrienols may difer in the methylation of the chroman head group: β‑ and γ‑ are structural isomers (5,8‑dimethyltocol and 7,8‑dimethyltocol), while α‑ (5,7,8‑trimethyltocol) and δ‑ (8‑methyltocol) difer from each other and from β‑ and γ‑, because they possess a methyl group (either one more or one less) in the aromatic ring (Mayer et al., 1967). Temelli et al. (2013) studied the total tocol content of whole‑grain barley varieties, which ranged between 40 mg/g and 151.1 mg/g. In whole‑grain barley, α‑tocotrienol is the most individual tocol isomer, contributing about 47.7% of the total tocol content (Andersson et al., 2008), followed by α‑tocopherol (17.7–33.9%), γ‑tocotrienol (10.4–20.2%), γ‑tocopherol (1.9e9.2%), β‑tocotrienol (2.9–7.8%), and δ‑tocotrienol (2.7–6.7%) (Temelli et al., 2013). Te average content of tocotrienol in barley is about 70.6–76.8% (Ward et al., 2008; Moreau et al., 2007). Zielinski (2006) reported that 95% of tocols occur in the endosperm, whereas 63% and 10% of tocols occur in the hull and germ components of barley, respectively. Hulled barley has been reported to possess more tocol content than hull‑less barley. Cavallero et al. (2004) reported higher tocol and α‑tocotrienol contents in hulled barley (53– 61 µg/g/g) than those in hull‑less barley (50.9–53.1 µg/g). 3.9 Carotenoids

Carotenoid pigments are natural lipophilic pigments that are responsible for the yellow, orange, and red colour of a wide range of fruits (Britton and Hornero‑Mendez, 1997; Liu, 2007). Carotenoids provide pigments for photosynthesis (chlorophyll), reproduction, protection, and colour in whole‑grain four and act as antioxidants in lipid environments of biological systems through their ability to scavenge free radicals. Cereal carotenoids (Figure 3.1k) are mainly composed of xanthophylls, with lutein as the most abundant, followed by zeaxanthin and β‑cryptoxanthin in addition to α‑ and β‑carotene in small

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amounts (Mellado‑Ortega and Hornero‑Mendez, 2015). Te distribution of carotenoid profles vary among genotypes of the same type of cereal (Siebenhandl et al., 2007) and within the same grain since lutein is distributed homogeneously while α‑carotene, β‑carotene, and zeaxanthin are concentrated in the bran and the germ (Borrelli et al., 2008; Konopka et al., 2004; Ndolo and Beta, 2013; Panfli et al., 2004). Te reported composition of carotenoids in cereals, i.e. for barley, millet, and rye, is fairly scarce (Choi et al., 2007; Kandlakunta et al., 2008; Mamatha et al., 2011). Panfli et al. (2003) reported the concentration of 40 mg/kg vitamin E compounds in barley grain. Goupy et al. (1999) reported tocopherol of 25.1 mg/kg in barley grains. Choi et al. (2007) reported 15 µg/100 g carotenoids in barley. 3.10 Tannins

Tannins are phenolic compounds with molecular weight ranging from 500 to 3000 D (Figure 3.1l) (Sanchez‑Moreno, 2002), and they are classifed into two major groups: hydrolysable tannins and/ or condensed tannins (Ragan and Glombitza, 1986). Hydrolyzable tannins have a centre of glucose or a polyhydric alcohol partially or completely esterifed with gallic acid, forming ellagitannins and gallotannin (Okuda et al., 1995). Te condensed tannins are polymers of catechin and/or leucoanthocyanidin, not readily hydrolyzed by acid treatment and are responsible for the characteristic of astringency of the vegetables (Staford, 1983). Condensed tannins have a high antioxidant activity in vitro compared to monomeric phenolic compounds (Hagerman et al., 1998). Te highest amount of tannin has been found in oats (1.1 mg/g) followed by barley (0.74 mg/g) (Collins, 1986). 3.11 Lignans

Lignans are polyphenolic bioactive compounds. Tey are a group of dietary phytoestrogen compounds that are present in a wide variety of plant foods including whole grains (Tomson et al., 1991). Tey are characterized by a group of dietary phytoestrogen compounds that constitute two coupled C6C3 units (Figure 3.1m). Te plant lignans in the human diet include secoisolariciresinol, matairesinol,

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syringaresinollariciresinol, and pinoresinol. Enterodiol and enterolactone (mammalian lignans) are reported to ofer protection against heart disease and hormone‑related breast and prostate cancers (Adlercreutz and Mazur, 1997; Johnsen et al., 2004). Mammalian lignans inhibit colon cancer cell growth, and induce cell cycle arrest and apoptosis (in vitro) (Qu et al., 2005), while lower cancer rates are associated with high dietary intakes of lignans (Adlercreutz and Mazur, 1997). Smeds et al. (2009) studied the content of lignans in barley, which was reported to include pinoresinol (71 µg/100 g), medioresinol (22 µg/100 g), syringaresinol (140 µg/100 g), lariciresinol (133 µg/100 g), cyclolariciresinol (28 µg/100 g), secoisolariciresinol (42 µg/100 g), secoisolariciresinol‑sesquilignan (24 µg/100 g), matairesinol (42 µg/100 g), oxomatairesinol (28 µg/100 g), and 7‑hydroxymatairesinol (541 µg/100 g) as major lignans and todolactol (127 µg/100 g), a‑conidendrin acid (33 µg/100 g), nortrachelogenin (15 µg/100 g), and lariciresinol‑sesquillgnan (6.6 µg/100 g) as minor lignans. 3.12 Alkylresorcinols

Alkyleresorsinols are plant‑derived phenolic lipids, especially found in whole‑grain cereals. Tey are 1,3‑dihydroxybenzene derivatives with an odd‑numbered n‑alkyl side chain at C‑5 on the benzene ring (Figure 3.1n). Tese compounds are found in the bran of wheat, rye, triticale, and barley (Ross et al., 2003). Alkylresorcinols have antibacterial, antifungal, and antioxidant properties (Tsuge et al., 1992), thus imparting various health benefts with whole‑grain cereal consumption (Ross et al., 2003). Te alkylresorcinols in barley were found to be lower than in other cereals, and values ranged from 30 to 50 mg/kg (Garcia et al., 1997, Mattila et al., 2005; Zarnowski et al., 2002). 3.13 Phytosterols

Barley is considered a good source of phytosterol, although barley’s phytosterol level is moderate compared with other major grains (Frølich et al., 2013). Barley grains generally contain phytosterols in

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both free and bound forms, esterifed to fatty acids, phenolic acids, steryl glucosides, or acylated steryl glycosides. Te level of esterifcation varies among varieties and around diferent parts of barley grain (Liu and Moreau, 2008). Higher levels of phytosterols have been identifed in the outer layers of the kernel. Te content of sterols in 10 barley varieties studied by Andersson et al. (2008) ranged between 820 and 1153 µg/g. Piironen et al. (2002) analyzed and compared the phytosterol content of major cereal grains with the highest plant sterol content (mean, 955 µg/g) determined in rye, followed by barley (761 µg/g), wheat (690 µg/g), and oat (447 µg/g). As in most cereals, sitosterol is the most abundant sterol form in barley, contributing about 53–61% of total sterols, followed by campesterol (14–20%). 3.14 β-Glucan

Oats and barley have gained interest as they possess cholesterol‑lowering and hypoglycemic efects (Anderson et al., 1991; Aman, 2006), and this property is mainly attributed to the soluble fbre fractions in them. β‑glucans are the linear polymers of glucose molecules connected by 70% of β‑(1–4) and 30% of β‑(1–3)‑linkages (Figure 3.1o). Te largest amounts of β‑glucan are found in barley (3–11%) and oats (3–7%), and lesser amounts have been reported in wheat ( enzymatic > acidic > alkaline. During the extraction process, chemicals are used along with water to remove starch and proteins; however, the chemical compounds have an adverse efect on β‑glucan’s biological activities and may be harmful for human consumption. So it is recommended that β‑glucan is extracted with high purity and less time. Recovery of β‑glucan is mainly afected by many indigenous enzymes such as endo‑β‑glucanase, endoxylase, xyloacetylesterase, arabinofuranosidase, etc. Among these, the most efective enzyme for the extraction of β‑glucan is observed to be endo‑β‑glucanase (Ahmad et al., 2012). 4.3 Utilization as an Ingredient

Barley is a versatile crop with a nutty favour and appealing chewiness. As a source of dietary fbre, barley has started to become functional

barley flour

hot water extraction

refluxing (80% ethanol) for 6 h

soluble residue

Figure 4.1

drying

Supernatant+ethanol (80%)

centrifuge for 25 min

Centrifuge and vacuum oven drying

Drying in vaccumm oven

centrifuge at 4o C

Supernatant+ethanol (hold for 20 min) adjust supernatant pH (7) by NaOH

centrifuge

supernatant +citric acid (1M, 1:3)

stirring and centrifuge

Mixing with citric acid (1M, 1:7)

adjust supernatant pH (4), centrifuge

Extraction methods of β‑glucan (Ahmad et al., 2009; Aktas‑Akyildiz et al., 2018).

Centrifuge and vacuum oven drying

supernatant+ethanol(80%)

Centrifuge

barley lour

acidic extraction

refluxing (80% ethanol) for 6 h

adjust supernatant pH (8.5), Stirring and centrifuge

insoluble residue

centrifugation

Inactivation of enzyme (2 min at 100 °C) stirring and centrifuge

adjust supernantant pH(7) with citric acid evaporation

centrifugation 20min at 40°C

Supernatant mixing with NaOH(1:3)

Centrifuge for 20min at 40°C

Mixing with NaOH (1M) (1:7) & stirring Incubation (4 h at 50 °C) in extruder Mixing with H2O

Enzyme (Depol 740L)

conditioning

Water (30%)

Barley flour

refluxing (80% ethanol) for 6 h

enzymatic extraction barley fraction

Alkaline extraction

-glucan extraction methods

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foods for humans, and β‑glucan‑supplemented food products are gaining interest due to their health benefts. Terefore, there is an interesting opportunity to incorporate barley four in bakery product formulations to improve their nutritional properties. Tis incorporation of β‑glucan also improves the physiochemical and sensorial behaviour of food products. Terefore, β‑glucan from barley may be utilized as an ingredient in various food products. It is also convenient to use in bakery products as it supplies functional and healthy meals with a relatively low cost and provides a characteristic nutty and crunchy taste. Te addition of β‑glucan provides characteristics like improved viscosity, water‑holding capacity, oil‑binding capacity, emulsion stabilization, and improvement in the organoleptic characteristics of these products (Ahmad et al., 2008, 2009; Tammakiti et al., 2004). β‑glucan is being incorporated in edible flms to improve transparency and tensile strength (Tejinder, 2003). Commercialization of bread fortifed with β‑glucan provides consumers an additional source of dietary fbre to assist them in coming closer to recommended daily intakes (Moriartey, 2009). As explained by Hajji et al. (2016), it is possible to improve the nutritional and textural properties of pasta using barley β‑glucans without compromising its cooking quality. Te addition of β‑glucan in bread is observed to increase shelf life and decrease the staleness of bread (Mohebbi et al., 2018). 4.4 Mechanism of Action

Human intestinal microfora alters from birth to adulthood and with ageing. Te major bacterial groups are Escherichia coli, Clostridium coccoides, and Clostridium leptum. Gut microfora stimulate the host immune system, help in nutrient absorption and fermentation of food, and protect against pathogens. Dietary fbres possess soluble and insoluble properties: soluble fbres behave as a substrate for fermentation in the large intestine, whereas insoluble fbres produce a bulking efect. Ingested dietary fbres reach the gastric tract and start to increase in size by absorbing water and ultimately provide satiety. As humans lack enzymes which hydrolyze β‑glucans, their digestion does not take place in the small intestine and they move over to the

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large intestine. Further, they undergo fermentation by the intestinal microfora and produce short‑chain fatty acids (SCFAs) like butyrate, acetate, and propionate. Butyrates are believed to be used as fuel for epithelial cells and have the potential to regulate cell diferentiation and intestinal absorption of fat. Acetates are taken from the large intestine and reach the liver, where they may be used as a substrate for the synthesis of cholesterol. Propionate shows hypocholesterolemic behaviour by preventing the utilization of acetate for the synthesis of cholesterol (Staka et al., 2015). As reported by Andersson (2009), although glucose and glutamine are available in the colon, the epithelial cells of the colon still use butyrate as an energy source. Butyrate also determines the growth of colonocytes and functions as a primary protective agent against many colonic diseases. Te production of SCFAs through fermentation also inhibits the growth of pathogenic microorganisms by reducing faecal pH. 4.5 Health Benefts

Numerous epidemiological studies have indicated that barley has good fbre content, particularly β‑glucans which may be useful in preventing chronic diseases (such as obesity and diabetes, by providing glycaemic and cholesterol control), bowel syndrome, and cancer (Figure 4.2). Clinical studies have demonstrated that β‑glucan intake also supports the health of the gastrointestinal tract, and emerging evidence suggests the benefts of β‑glucans in weight management. Wolever et al. (2010) concluded that a daily intake of 3.0–4.0 g of β‑glucan have been shown to promote health through the maintenance of normal blood cholesterol and glucose levels. 4.5.1 Reduction of Cholesterol

According to the World Health Organization (WHO, 2016), cardiovascular diseases have major contribution in mortality. Sedentary lifestyle, inadequate or overnutrition, and low energy expenditure may increase the risk of cardiovascular diseases. Hypercholesterolemia is one of the primary risk factors of cardiovascular disease, together with metabolic syndrome, hypertension, and diabetes. Cholesterol is

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-glucan Stomach (depolymerisation only) small intestine (viscous) Colon (fermentation)

Formation of butyric acid, acetic acid, propionic acids

Health Benefits 1. Anti-carcinogenic behaviour 2. Maintain cholesterol 3. Prevent hypertension 4. Regulate blood glucose 5. Body weight management

Figure 4.2

Mechanism of health benefts.

a biologically active compound for the survival of living organisms and it serves as a basic structural component of the cell membrane. Synthesis of bile acids takes place in the liver through the oxidation of cholesterol (by cholesterol‑7α‑hydroxylase), and about 10–20% of absorbed biles are excreted in faeces. Te associated health benefts of β‑glucans are due to their viscous behaviour in an aqueous medium. Consumption of these dietary fbres increases chyme viscosity in the upper gastrointestinal tract, leading to the binding of bile acids (Ellegård and Andersson, 2007) and promotes their excretion from the body through faeces. If biles are excreted in large amounts, they must be newly synthesized in the liver (Russell, 2003), and for the synthesis of bile acids, cholesterol is utilized, which ultimately lowers blood cholesterol levels. 4.5.2 Reduction of Blood Glucose/Diabetes

For performing daily activities, diet plays an important role. Unbalanced and excess diet intake disturbs energy homeostasis, leading to metabolic disorders. β‑glucans have the potential to increase plasma gut hormones (PYY and GLP‑1) which suppress appetite, increase

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intestinal transit rate, and promote insulin secretion (Chambers et al., 2015a). Te viscous nature of β‑glucans is responsible for the reduction of blood glucose levels. After ingestion, barley β‑glucans increase their size by absorbing water and mix with chyme. As a result, digestive enzymes binding with chyme are reduced and emptying of the stomach is delayed. Many epidemiological studies demonstrated that β‑glucans reduce the digestion of starch and absorption of glucose in the intestinal tract (Schloermann and Glei, 2017). As reported by Tosh (2013), dietary fbres have the potential to reduce the glycaemic response by delaying gastric emptying by which satiety increases and food intake is reduced. 4.5.3 Hypertension

Hypertension is a risk factor for heart diseases, stroke, and renal diseases. Increased dietary fbre consumption has provided a safe and acceptable means to reduce blood pressure in patients with hypertension (Tosh, 2013). A crossover study conducted by Jenkins et al. (2002) on hyperlipidemic adults suggested that a diet containing β‑glucans of 8 g/day helps in the reduction of blood pressure. β‑glucans help in controlling insulin metabolism, induce weight management, and improve vasodilation, and through this mechanism they exhibit antihypertensive efects on arterial blood pressure. However, more research work is still needed to fully elucidate the mechanisms of the protective efect of β‑glucans against hypertension. 4.5.4 Anti-Carcinogenic Behaviour

β‑glucan dietary fbre behaves as prebiotics for intestinal microfora and improves the growth of Enterococcus and Lactobacillus to prevent cancer (O’Keefe, 2016). After passing intact from the small intestine, β‑glucan reaches the colon/large intestine where it serves as a prebiotic and improves gastrointestinal health by stimulating benefcial intestinal microfora. Tese microfora convert β‑glucan into SCFAs through the fermentation process. Tese SCFAs like butyric acid, acetic acid, and propionic acid have the potential to induce chemopreventive efects (Schloermann and Glei, 2017). Schloermann and Glei

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(2017) further explain that among SCFAs, butyrates are the main products of fermentation and serve as an energy source for colon cells as well as act as a histone deacetylase inhibitor. Tey have the potential to inhibit the growth of already degenerated cells and to induce apoptosis (Hinnebusch et al., 2002; Schlörmann et al., 2012). 4.5.5 Body Weight Management and Obesity

Excessive intake of fat and carbohydrates, insufcient physical activity, and genetic factors are responsible for obesity (Malik et al., 2013). Increased intake of dietary carbohydrates that are fermented in the colon by the microbiota has been reported to decrease body weight (Frost et al., 2014) and improve appetite regulation (Liu et al., 2003). As explained by Chambers et al. (2015b), β‑glucans are fermented in the colon and produce SCFAs, which stimulate peptide tyrosine (PYY) and glucagon‑like‑peptide‑1 (GLP‑1) through the activation of free fatty acid receptor 2 (FFAR2) on L‑cells of colons. PYY and GLP‑1 increase the appetite‑suppressing proopiomelanocortin’s activity, inhibit appetite‑stimulating neuropeptide Y and the motility of the upper gastrointestinal tract by which emptying of ingested foods slows down. SCFAs like propionates are taken up by the liver and stimulate hepatic gluconeogenesis and leptin (a hormone to regulate energy balance by inhibiting hunger) through the activation of FFAR2. Tus, increasing SCFA stimulates multiple hormonal and neural mechanisms that suppress appetite and energy intake and ultimately prevent obesity. 4.5.6 Immunity

Te consumption of β‑glucans has regulatory efects, and they behave as activators of the innate immune system as they have the potential to activate macrophages, neutrophils, and phagocytosis of pathogens. After passing through the stomach, β‑glucans are taken up into Peyer’s Patches (immune sensor of the small intestine) and transported to immune cells (macrophages, etc.) through M‑cells (Figure 4.3). Macrophages play an important role in host defence mechanism when infection takes place. Te β‑glucans are taken up by macrophages

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-glucan M-cells (intestinal cell wall) transports Activation of macrophages Digestion and Fragmentation of -glucan

Bone marrow

Stimulates production of immune cells

Figure 4.3

other immune cells (B cells & T-cells)

activity increases

Mechanism of the immune response of β‐glucan.

through the Dectin‑1 receptor and fragmented into smaller ones. Tese smaller β‑glucan fragments are taken up by monocytes, granulocytes, and macrophages through the complement receptor, and ultimately the immune response will be turned on (Chan et al., 2009), releasing phagocytes and lysosomal enzymes to digest the pathogens which cross epithelial cells. Terefore, the activation of macrophage functions by β‑glucans increases the host immune defence (Akramienė et al., 2007) and enhances resistance to bacterial, viral, and fungal diseases as well as promotes antitumor activity. 4.6 Conclusions

β‑glucans are functional ingredients of great importance because they have been shown to exert multiple health benefts like lowering of blood glucose, blood pressure, cholesterol, and obesity and help in the prevention of colon cancer. Te associated health benefts of β‑glucans may be due to their viscous behaviour and the formation of SCFAs in the colon through the fermentation process. Because of the presence of functional compounds and the health benefts they possess, β‑glucans may be uniquely positioned to be used as an ingredient that food manufacturers can use in the development of new and innovative functional products to meet the population’s dietary fbre needs.

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Ahmad, A., Anjum, F. M., Zahoor, T., Chatha, Z. A., and Nawaz, H. 2008. Efect of barley β‑glucan on sensory characteristics of bread. Pakistan Journal of Agricultural Sciences 45(1):88–94. Ahmad, A., Anjum, F. M., Zahoor, T., Nawaz, H., and Dilshad, S. M. R. 2012. Beta glucan: A valuable functional ingredient in foods. Critical Reviews in Food Science and Nutrition 52(3):201–212. Ahmad, A., Anjum, F. M., Zahoor, T., Nawaz, H., and Din, A. 2009. Physicochemical and functional properties of barley β‑glucan as afected by diferent extraction procedures. International Journal of Food Science and Technology 44(1):181–187. Akramienė, D., Kondrotas, A. J., Didžiapetrienė, J., and Kėvelaitis, E. 2007. Efects of beta‑glucans on the immune system. Medicina 43(8):597–606. Aktas‑Akyildiz, E., Sibakov, J., Nappa, M., Hytönen, E., Koksel, H., and Poutanen, K. 2018. Extraction of soluble β‑glucan from oat and barley fractions: Process efciency and dispersion stability. Journal of Cereal Science 81:60–68. Andersson, K. 2009. Molecular weight of beta glucans, bioactivity. Doctoral dissertation. Lund University, Faculty of Medicine, Sweden. Lund: Media‑tryck. 67 pp. Chambers, E. S., Viardot, A., Psichas, A., Morrison, D. J., Murphy, K. G., Zac‑Varghese, S. E., MacDougall, K., Preston, T., Tedford, C., Finlayson, G. S., Blundell, J. E., Bell, J. D., Tomas, E. L., Mt‑Isa, S., Ashby, D., Gibson, G. R., Kolida, S., Dhillo, W. S., Bloom, S. R., Morley, W., Clegg, S., and Frost, G. 2015a. Efects of targeted delivery of propionate to the human colon on appetite regulation, body weight maintenance and adiposity in overweight adults. Gut 64(11):1744–1754. Chambers, E. S., Morrison, D. J., and Frost, G. 2015b. Control of appetite and energy intake by SCFA: What are the potential underlying mechanisms? Te Proceedings of the Nutrition Society 74(3):328–336. Chan, G. C. F., Chan, W. K., and Sze, D. M. Y. 2009. Te efects of β‑glucan on human immune and cancer cells. Journal of Hematology and Oncology 2(1):25. Ellegård, L., and Andersson, H. 2007. Oat bran rapidly increases bile acid excretion and bile acid synthesis: An ileostomy study. European Journal of Clinical Nutrition 61(8):938. Frost, G., Sleeth, M. L., Sahuri‑Arisoylu, M., Lizarbe, B., Cerdan, S., Brody, L., Anastasovska, J., Ghourab, S., Hankir, M., Zhang, S., Carling, D., Swann, J. R., Gibson, G., Viardot, A., Morrison, D., Louise Tomas, E., and Bell, J. D. 2014. Te short‑chain fatty acid acetate reduces appetite via a central homeostatic mechanism. Nature Communications 5:3611. Hajji, T., Sfayhi‑Terras, D., Felah, M. E., Rezgui, S., and Ferchichi, A. 2016. Incorporation of β‑glucans into pasta extracted from two Tunisian barley cultivars. International Journal of Food Engineering 12(7):701–710.

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Hinnebusch, B. F., Meng, S., Wu, J. T., Archer, S. Y., and Hodin, R. A. 2002. Te efects of short‑chain fatty acids on human colon cancer cell phenotype are associated with histone hyperacetylation. Te Journal of Nutrition 132(5):1012–1017. Izydorczyk, M. S., and Dexter, J. E. 2008. Barley β‑glucans and arabinoxylans: Molecular structure, physicochemical properties, and uses in food products–A review. Food Research International 41(9):850–868. Jenkins, A. L., Jenkins, D. J. A., Zdravkovic, U., Würsch, P., and Vuksan, V. 2002. Depression of the glycemic index by high levels of β‑glucan fber in two functional foods tested in type 2 diabetes. European Journal of Clinical Nutrition 56(7):622. Li, J., Kaneko, T., Qin, L. Q ., Wang, J., and Wang, Y. 2003. Efects of barley intake on glucose tolerance, lipid metabolism, and bowel function in women. Nutrition 19(11–12):926–929. Liu, S., Willett, W. C., Manson, J. E., Hu, F. B., Rosner, B., and Colditz, G. 2003. Relation between changes in intakes of dietary fber and grain products and changes in weight and development of obesity among middle‑aged women. Te American Journal of Clinical Nutrition 78(5):920–927. Madhujith, T., Izydorczyk, M. S., and Shahidi, F. 2006. Antioxidant properties of pearled barley fractions. Journal of Agricultural and Food Chemistry 54(9):3283–3289. Maheshwari, G., Sowrirajan, S., and Joseph, B. 2017. Extraction and isolation of β‑glucan from grain sources–A review. Journal of Food Science 82(7):1535–1545. Malik, V. S., Willett, W. C., and Hu, F. B. 2013. Global obesity: Trends, risk factors and policy implications. Nature Reviews: Endocrinology 9(1):13. Mohebbi, Z., Homayouni, A., Azizi, M. H., and Hosseini, S. J. 2018. Efects of beta‑glucan and resistant starch on wheat dough and prebiotic bread properties. Journal of Food Science and Technology 55(1):101–110. Moriartey S. 2009. β‑Glucan in bread: the journey from production to consumption [PhD Dissertation]. Edmonton, AB, Canada: University of Alberta. O’Keefe, S. J. 2016. Diet, microorganisms and their metabolites, and colon cancer. Nature Reviews. Gastroenterology and Hepatology 13(12):691. Reed, G., and Nagodawithana, W. T. 1991. Yeast Technology. Dordrecht: Springer, 261–314. Russell, D. W. 2003. Te enzymes, regulation, and genetics of bile acid synthesis. Annual Review of Biochemistry 72(1):137–174. Schloermann, W., and Glei, M. 2017. Potential health benefts of β‑glucan from barley and oat. Ernahrungs Umschau 64(10):145–149. Schlörmann, W., Hiller, B., Jahns, F., Zöger, R., Hennemeier, I., Wilhelm, A., Lindhauer, M., and Glei, M. 2012. Chemopreventive efects of in vitro digested and fermented bread in human colon cells. European Journal of Nutrition 51(7):827–839.

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Staka, A., Bodnieks, E., and Puķītis, A. 2015. Impact of oat‑based products on human gastrointestinal tract. In: Proceedings of the Latvian Academy of Sciences. Section B. Natural, Exact, and Applied Sciences. (vol. 69, no. 4). Berlin: De Gruyter, Open, 145–151. Tejinder, S. 2003. Preparation and characterization of flms using barley and oat β‑glucan extracts. Cereal Chemistry 80(6):728–731. Tammakiti, S., Suphantharika, M., Phaesuwan, T., and Verduyn, C. 2004. Preparation of spent brewer’s yeast β‑glucans for potential applications in the food industry. International Journal of Food Science and Technology 39(1):21–29. Tosh, S. M. 2013. Review of human studies investigating the post‑prandial blood‑glucose lowering ability of oat and barley food products. European Journal of Clinical Nutrition 67(4):310. Wolever, T. M., Tosh, S. M., Gibbs, A. L., Brand‑Miller, J., Duncan, A. M., Hart, V., Lamarche, B., Tomson, B. A., Duss, R., and Wood, P. J. 2010. Physicochemical properties of oat β‑glucan infuence its ability to reduce serum LDL cholesterol in humans: A randomized clinical trial. Te American Journal of Clinical Nutrition 92(4):723–732. World Health Organization. 2016. Cardiovascular Disease. Geneva: World Health Organization. Zielke, C., Kosik, O., Ainalem, M. L., Lovegrove, A., Stradner, A., and Nilsson, L. 2017. Characterization of cereal β‑glucan extracts from oat and barley and quantifcation of proteinaceous matter. PLOS ONE 12(2):e0172034.

5 E FFECT

OF

P RO CES SIN G

N UTRITION AND A NTI OXIDANT P ROPERTIES ON

5.1 Introduction

Cereals are an important part of diets and contribute substantially to the nutrient intake of human beings (Oghbaei and Prakash, 2016). Barley is among the most ancient cereal crops grown in the world today. Te food industry is now facing the challenge of developing novel barley ingredients and palatable and healthy barley‑based products that will gain acceptance among consumers and deliver the promised health benefts (Izydorczyk and Dexter, 2016). Epidemiological studies reported that the regular consumption of barley promotes health due to the presence of many functional components. Generally, barley is used for alcoholic beverages and as animal feed, and only 2% of barley is used for human consumption. Presence of husk that is difcult to remove, most of the barley is used up by the malting and brewing industry, lack of gluten proteins, and strong taste make barley unpopular as human food (Sharma and Gujral, 2010a). Terefore, these cereal grains are subjected to diferent processing methods to improve their nutritional characteristics, sensory properties, and nutritive value by the gelatinization of starch, denaturation of proteins, increased nutrient availability, and inactivation of heat‑labile toxic compounds and other enzyme inhibitors (Bakr and Gowish, 1991). Te technological production processes of barley groats include cleaning, conditioning, size sorting, dehulling, and sorting after dehulling (Dziedzic et al., 2012). Traditional household food processing and preparation methods may be used to enhance the bioavailability of 77

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micronutrients in plant‑based diets. Several studies on barley have reported that diferent processing methods may reduce or increase the phenolic content and their antioxidant activities, depending on the severity of the heat treatment, time of exposure, and the type of cereal tested (Hegde and Chandra, 2005; Towo et al., 2003; Zielinski et al., 2006). Tis chapter aims to understand the infuence of diferent processing methods (dehulling, pearling, milling, germination, and fermentation and thermal treatments, roasting, extrusion, cooking, etc.) on the nutritional and phytochemical properties of barley grains (Tables 5.1–5.3). Table 5.1 Different Methods for Processing METHODS

DEFINITION

Dehulling/ pearling

The process is an abrasive scouring process which involves the removal of the indigestible part (hull and outer layers) and the mass fraction of the grain (Felizardo and Freire, 2018). Pearling is a process of abrasive scouring that gradually removes the hull, pericarp, seed coat, aleurone and subaleurone layers, and the embryo (Izydorczyk and Dexter, 2016). Milling is the transformation of raw materials into fner primary products for secondary processing. In cereal grains, milling is a process that separates the bran and germ from the starchy endosperm to produce white four for use in making bakery products (Ragaee et al., 2014). Germination induced the synthesis or activation of a range of hydrolytic enzymes in the germinated grain, resulting in structural modifcation or synthesis of new compounds with high bioactivity or nutritional value (Wang et al., 2014). Solid substrate fermentation is a process for enhancing antioxidant potential, which involves the growth and metabolism of microorganisms on moist solid substrates in the absence of free fowing water (Babu and Satyanarayana, 1995) to give desirable changes and to modify food quality (Sandhu et al., 2017b). Extrusion cooking is a high-temperature short-time process, which preserves important nutrients, denatures antinutritional components of foods (trypsin inhibitors, tannins, and phytates), disinfects the fnal product, and maintains normal colours and favours of the food (Gbenyi et al., 2016; Guy, 2001). Roasted barley, or satu, is consumed widely in India. Roasting in hot sand at 280°C for 2 minutes causes the barley grains to expand and puff, thus splitting the husk (Rashid et al., 2015). It is a hydrothermal treatment which induces signifcant changes in the chemical composition, affecting the bioacessibility and the concentration of nutrients and health-promoting compounds (Pellegrini et al., 2010).

Milling

Germination

Fermentation

Extrusion cooking

Roasting

Cooking

79

EF F EC T O F P R O C E S SIN G

Table 5.2 Effect of Different Treatments on Nutritional Quality of Barley METHODS

EFFECTS

Dehulling/ pearling

Pearling reduces the contents of the insoluble fbre, proteins, ash, and free lipids. Loss of tocols, proteins, and valuable minerals along with the bran and germ is a negative effect brought about by pearling. The pearling process improves the storage stability and overall quality. It improves the texture, colour, and cooking quality of the respective grains. Milling of barley reduces minerals by 60% and also causes signifcant loss of protein and lysine. Bioavailability of nutrients also improves signifcantly as a result of the degradation of proteins by protease enzymes. The steeping process results in a signifcant reduction in vitamin E and antioxidant activity. Polyphenol, β-carotenoid, and vitamin C were observed to be increased during the germination process. It decreased the level of phytates from 0.683% to 0.467%. Decreased antinutritional factors. Softening the kernel structure, improving its nutritional value, and reducing antinutritional effects. Bioavailability of nutrients improved. A signifcant decrease in polyphenols from 352.64 to 278.72 mg/100 g after 36 hours.

Milling Germination

Fermentation

REFERENCES Quinde et al. (2004) Yeung and Vasanthan (2001) Morrison (1993) Scheuring and Rooney (1979) Lachance and Bauernfeind (1991) Singh et al. (2015)

Do et al. (2015) Do et al. (2015); Dabina-Bicka et al. (2010) Hübner et al. (2010) Gupta and Sehgal (1991) Tian et al. (2010)

Singh et al. (2015) Tiwari et al. (2014)

Table 5.3 Effect of Heat Treatments on the Nutritional Quality of Barley THERMAL TREATMENTS Extrusion

RESULTS Extrusion cooking improves the nutritional quality of the products by improving starch and protein digestibility and increasing the retention of bioactive compounds with antioxidant properties. When subjected to heat treatment carried out at 140–160°C with a screw (150–200 rpm), a signifcant reduction in both antioxidant capacity (60–68%) and total phenolics (46–60%) in barley extrudates compared with unprocessed barley four is observed. Extrusion cooking reduces the antinutritional factors, renders the product microbially safe, and enhances consumer acceptability.

REFERENCES Moreno et al. (2017) Altan et al. (2009)

Nibedita and Sukumar (2003) (Continued)

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Table 5.3 (Continued)

Effect of Heat Treatments on the Nutritional Quality of Barley

THERMAL TREATMENTS

Roasting

Cooking

RESULTS

REFERENCES

Extrusion cooking (twin-screw extruder) with die temperature (120–160–200°C), screw speed (500 rev/min), and mass fow rate (225 g/min) performed on barley cultivars resulted in a 200–300% increase in the content of phenolic acids, free and released from ester bonds, and a decrease of 91.4% and 81.8% in tocopherols and tocotrienols. An increase in enzyme-resistant starch content in barley (2–3%) after extrusion. A decrease in total phenolic content was observed after sand roasting. A decrease in total phenolic compounds was observed, which may be due to the thermal degradation of heat-sensitive phenolic compounds. Roasting improves texture, crispness, and volume of the grains due to puffng (Hoke et al., 2007). The digestibility, colour, favour, and shelf life of cereals and legumes are also improved by roasting, which reduces antinutrient factors. Upon cooking process, β-glucan was increased, and phytate content was decreased, but cooking did not have a signifcant infuence on the content of Fe, Cu, Zn, or Mg.

Zielinski et al. (2001)

Huth et al. (2000) Rashid et al. (2015) Randhir et al. (2008) Gahalawat and Sehagal (1992) Köksel et al. (1999)

5.2 Processing 5.2.1 Dehulling/Pearling

Pearled barley is prepared by abrasive milling to remove a part of the kernel’s outer layer to be used as a food ingredient in a variety of foods. Hulled barley needs to be dehulled before further processing because the hull is not removed during threshing (Izydorczyk and Dexter, 2016). Te inedible hull is frmly attached to the pericarp; thus, barley grains are generally pearled through an abrasive scouring process that gradually removes the hull, the bran with the seed coat (testa and pericarp) and aleurone layers, and the germ (Quinde et al., 2004). Te dehulling process is an abrasive scouring process which involves blocking and pearling. Blocking removes the indigestible part (hull and outer layers), whereas pearling removes the mass fraction of the grain (Felizardo and Freire, 2018). Dehulling is usually done in pearling machines (pearler) or in compressed air dehullers that use a stream of pressurized air to apply mechanical shock to the

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barley grains, which knocks the hull of the kernel. A pearler is generally composed of six to eight abrasive carborundum‑ or emery‑coated disks, which revolve at a high speed (∼450 rpm) within a perforated cylinder or a closed chamber (Leonard and Martin, 1963). Hulls are subsequently removed by aspiration (Izydorczyk and Dexter, 2016). Pearling removes the components present in the outer layers of the barley kernel, thus changing the composition of the grains (Izydorczyk and Dexter, 2016). It improves the texture, colour, and cooking quality of the grains (Scheuring and Rooney, 1979) and reduces the contents of insoluble fbres, proteins, ash, and free lipids (Quinde et al., 2004). A progressive decrease in total phenolics, antioxidant capacity, and the levels of phenolic acids (vanillic, cafeic, p‑coumaric, ferulic, and sinapic acids) was observed by Madhujith et al. (2006) as the degree of pearling was increased. Jaybhaye et al. (2014) reported that dehulling coupled with hydrothermal treatment methods afects the phenolic content and the antioxidant potential. Bhatty and Rossnagel (1998) compared Canadian and Japanese barleys and reported that pearling up to 55% decreased β‑glucan, total dietary fbre content, ash, and protein content but increased starch and soluble fbre content. However, in terms of the nutritional quality of pearled barley, the loss of tocols, proteins, and valuable minerals, along with the bran and germ, is a negative efect brought about by pearling (Yeung and Vasanthan, 2001). Barley lipid contains an appreciable amount of oleic and linoleic unsaturated fatty acids, which are highly prone to autoxidation and subsequent rancid odour development. Te pearling process improves the storage stability and overall quality (Morrison, 1993). Liu and Moreau (2008) found that pearling had a signifcant efect on the enrichment of functional lipids in the kernels. Besides this, pearling also removes phenolic compounds and enzymes, such as polyphenol oxidase and peroxidase, along with the outer layers of the grain. Polyphenol oxidase reacts with phenolic compounds to produce o‑quinones, which further react with other phenolic compounds or amino acids to give discolouration in various foods made from barley (Sapers, 1993). Te discolouration in foods by polyphenol oxidase is another reason that limits the use of barley as a food ingredient (Lagassé et al., 2006).

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5.2.2 Milling

Milling is an important and intermediate step in the postproduction of grains and transformation of raw materials into fner primary products for secondary processing (Bender, 2006). In cereal grains, milling is a process that separates the bran and germ from the starchy endosperm to produce white four for use in making bakery products. Te basic objective of the milling process is to remove the husk and bran layers and to produce an edible portion that is free of impurities and in the form of a powder with varying particle sizes. Te distribution of nutritional components in barley is not uniform; therefore, milling may be useful in the fractionation of barley into various products enriched in specifc constituents (Izydorczyk et al., 2011). Te traditional food processing of barley produces pot and pearled barley, fakes, and four by roller‑milling pearled barley. Te concentration of essential nutrients decreases with the degree of milling with minor alterations in the energy density of pre‑ and post‑meal (Ramberg and McAnalley, 2002). Milling of barley reduces minerals by 60% and also causes signifcant loss of protein and lysine (Lachance and Bauernfeind, 1991). Most roller‑milling processes nowadays focus on producing β‑glucan/dietary fbre‑enriched fractions or whole grain four to create milled products with potential and/or proven health benefts (Izydorczyk and Dexter, 2016). 5.2.3 Germination

Te terms “germination,” “sprouting,” and “malting” are interchangeable and used as synonyms (Hassani et al., 2016; Hübner and Arendt, 2013; Singh and Sharma, 2017), and malting is a specifc form of sprouting. It is a common household technique carried out at low cost without the use of any sophisticated and expensive equipment and has been claimed to improve the nutritive quality of cereals and has been used for centuries for the purpose of softening the kernel structure, improving its nutritional value, and reducing antinutritional efects (Gupta and Sehgal, 1991; Tian et al., 2010). Te germination process is found to be responsible for the activation of the enzymatic activity of sprouted seeds, thereby causing the disintegration of carbohydrates,

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proteins, and lipids into simpler forms. Te bioavailability of nutrients also improved signifcantly as a result of the degradation of proteins by protease enzymes (Singh et al., 2015). It produces fermentable extracts for the brewing and distilling industries (Lemmens et al., 2019). Germination results in biochemical modifcations and produces malt with improved nutritional quality that may be used in various traditional recipes (Saleh et al., 2013). Sorghum and barley are the two principal cereal grains that are malted and used in the production of opaque beer (sorghum malt) and lager beer (both sorghum and barley malt) (Duodu, 2011). Vinje et al. (2015) showed that sprouting of barley decreased the starch content by 3% in barley sprouted for 4 days at 17°C. Hübner et al. (2010) germinated barley at temperatures between 10°C and 20°C for a period of 2–6 days and showed that germination of barley decreased the level of phytates from 0.683% to 0.467%. Phytates are known for lowering the bioavailability of some minerals due to the formation of complexes. Te formation of phytate‑degrading enzymes as well as the breakdown of phytates during the germination of barley has been explained by Centeno et al. (2001). It is possible to retain the amounts of soluble dietary fbres when short germination periods are applied. However, long germination periods caused extensive breakdown of soluble dietary fbres, especially β‑glucan (Hübner et al., 2010). According to a study conducted by Teixeira et al. (2016), barley was subjected to sprouting and an increase in protein content was observed, but total fbre content was not afected signifcantly when sprouted for 3 days at 15°C. Sprouting results in higher protein solubility and digestibility. Osman et al. (2002) reported a twofold (approx.) increase in protein solubility in barley when sprouted for 4 days at 17°C. Tese results are in agreement with Chung et al. (1989) who observed an increment of 65–80% in protein digestibility in barley when sprouted for 2–6 days at 22°C. For instance, Haraldsson et al. (2004) and Teixeira et al. (2016) reported that the β‑D‑glucan content in barley does not change signifcantly when steeped in 0.4–0.8% lactic acid solution at 35–48°C and subsequently sprouted for 3–4 days at 15°C. Moreover, Rimsten et al. (2002) found that the β‑D‑glucan content only decreases by 11–14% when barley is steeped at 48°C and then sprouted at 15–18°C

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for 4 days, while a 40% decrease in β‑D‑glucan content occurs in barley grains steeped at 15°C and then sprouted at 15–18°C for 4 days. Do et al. (2015) reported that the steeping process resulted in a signifcant reduction in vitamin E and antioxidant activity and suggested that the loss of antioxidant activity after the steeping process is due to the loss of vitamin E. It is believed that after steeping, the loss of vitamin E is not the sole reason for the reduction in antioxidant activity; other compounds appear to also contribute to the overall antioxidant activity of barley. Phenolic compounds such as cafeic acid, vanillic acid, and gallic acid may have leached from the pericarp and testa of the barley or formed insoluble complexes with proteins during steeping (Lu et al., 2007). However, polyphenol, β‑carotenoid, and vitamin C were observed to be increased during the germination process (Do et al., 2015; Dabina‑Bicka et al., 2010). Te malting process is associated with an increase in antioxidant capacity, and this increase in antioxidant capacity after malting may be due to the release of phenolic compounds bound to cellular structures, better extraction methods, or the formation of Maillard reaction products (Maillard et al., 1996). Generally, phenolic acids are bound to lignin and arabinoxylans and during the germination process they are released in the presence of enzymes that are synthesized and/or activated during either the fnal stages of germination or the early stages of kilning. A signifcant decrease in total phenolic content was observed after 12 hours of germination, but a subsequent increase was found after a 24‑hour germination period. Antioxidant activity increased after 12 hours of germination and increased further after 24 hours (Sharma and Gujral, 2010b). 5.2.4 Fermentation

Fermentation is known as the oldest process of biotechnology, which dates back to about 5000 years ago when barley was converted to beer (Borgstrom, 1968). Fermentation is an ancient method used to enhance shelf life and retain nutritional and organoleptic qualities of the food products (Frias et al., 2005) and may be used to improve the product’s properties by changing the ratio of the nutritive and antinutritive components of the plants (Ðordevic et al., 2010). Troughout

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history, fermentation has been used to improve the product’s properties. During fermentation, the grain constituents are modifed by the action of both endogenous and bacterial enzymes, thereby afecting their structure, bioactivity, and bioavailability (Hole et al., 2012). Fermentation also enhances the levels of bioactive compounds and can be used to improve the product’s properties (Sandhu and Punia, 2017; Sandhu et al., 2016). Initially, fungi were mostly used for the fermentation process (as these microorganisms were considered to be optimally active in very low water conditions). Later, many bacterial species and yeasts were also used to carry out the fermentation process (Singhania et al., 2009). Filamentous fungi are the commonly used microorganisms for fermentation as they have great potential to produce bioactive compounds (Sandhu et al., 2017). Te fermentation process (Figure 5.1) using diferent types of microorganisms has been studied in depth over the years. In recent years, studies on Aspergillus awamorinakazawa (Sandhu and Punia, 2017), Lactobacillus rhamnosus, Saccharomyces cerevisiae (Ðordevic et al., 2010), Lactobacillus Barley grains (raw) Cleaning Dehulling malting/germination

fermentation

soaking in formaldehyde soaking(NaNO3(2.5g/l) (at 30 °C for 6hours) KH2PO4 (1 g/l), KCl (0.5 g/l) & MgSO4.2H2O (0.5 g/l) Draining

aeration (3 hr) sun drying grinding flour

decantation Autoclave (121 °C for 15 min) moisture content & pH (45%,6) strain (10%w/v) sprayed on grains incubation (6 days) oven drying, grinding & flour

Figure 5.1 Flow diagram of germination and fermentation (Bhati et al., 2016; Sandhu et al., 2016).

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acidophilus, Lactobacillus johnsonii, and Lactobacillus reuteri (Hole et al., 2012) have been carried out. Sandhu and Punia (2017) fermented barley grains with a fungal strain Aspergillus awamorinakazawa and incubated the grains for 6 days at 30°C. Te results revealed that A. awamorinakazawa used for solid substrate fermentation (SSF) efectively increased the total phenolic, total favonoid, and total antioxidant activities of all the barley cultivars studied. Further, they concluded that the antioxidants increased till the ffth day of fermentation and thereafter they decreased. Ðordevic et al. (2010) examined the infuence of fermentation using L. rhamnosus and S. cerevisiae and stated that the total phenolics and antioxidant activities of barley were increased; therefore, fermentation ofers a tool to further increase the bioactive potential of cereal products. Enzymes produced by microorganisms are capable of breaking down the cereal cell wall matrix, resulting in greater accessibility of bound and conjugated phenolic compounds (Hole et al., 2012). Tey also observed that after fermentation ferulic acid was 81.9% higher than in nonfermented barley. 5.2.5 Termal Treatment

Termal processing is an efective approach to improve the shelf life and the quality of a product (Randhir et al., 2008). It may decrease or increase the bioactive compounds of cereals, depending on the heat treatment method, the time period, and the type of cereal tested (Hegde and Chandra, 2005; Zielinski et al., 2006). Cereal thermal processing (baking, roasting, and extrusion) results in gelatinization of starch, protein denaturation, interactions between food components, and browning reactions, which help in improving organoleptic and antioxidant properties, increased nutrient availability, and inactivation of heat‑labile toxic compounds and enzyme inhibitors (Ragaee et al., 2014). Termal processing, such as roasting and extrusion cooking, leads to a signifcant increase in water absorption capacity (Sharma and Gujral, 2013; Fasina et al., 1999). Lee and Inglett (2006) studied the efect of the hydrothermal treatment method on barley four and reported a water solubility index of 15.8% for control four, which after hydrothermal treatment increased to 20.2%.

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Improved antioxidant properties may be due to the release of bound phenolic acids by the breakdown of cellular constituents and cell walls during thermal processing (Dewanto et al., 2002). Many researchers found that thermal processing enhances the nutritive value of plant products and increases the release of antioxidant compounds from the cellular structure (Chen et al., 2017; Pérez‑Conesa et al., 2009; Pinto et al., 2018). Browning, Maillard reaction (nonenzymatic browning), caramelization, and chemical oxidation of phenols contribute to an increase in the total phenol content during thermal processing. Enhancements in total phenolic compound (TPC) during browning may be due to the dissociation of conjugated phenolic moiety followed by some polymerization and/or oxidation reactions and the formation of phenolics other than those endogenous in the grains (Ragaee et al., 2014). During thermal decomposition, vanillic acid and vanillin from ferulic acid (Fiddler et al., 1967; Pisarnitskii et al., 1979; Peleg et al., 1992) and p‑hydroxybenzaldehyde from p‑coumaric acid (Pisarnitskii et al., 1979) may be formed. In contrast, Randhir et al. (2008) reported that heat treatment impairs the bioactive ingredients because the high temperature may weaken the activities of the bioactive compounds such as vitamin C and other antioxidant compounds. Cafeic, ferulic, and p‑coumaric acids are susceptible to heat and may be degraded or reduced during thermal treatment (Steinke and Paulson, 1964; Pisarnitskii et al., 1979; Huang and Zayas, 1991). 5.2.5.1 Extrusion Extrusion cooking is a high‑temperature short‑time

(HTST) process that improves the quality of the end products and is used worldwide for the production of expanded snacks, modifed starch, pet foods and porridge, and ready‑to‑eat cereal foods (Frame, 1994; Smith and Singh, 1996; Akdogan, 1999). Tis method may be used for the processing of starchy as well as proteinaceous materials (Jaybhaye et al., 2014) that contribute to the form, structure, texture, mouth feel, and bulk density. Te nonnutritive components, mainly polyphenols having antioxidant properties, may undergo various changes, thus altering their antioxidant activity (Sharma et al., 2012). Extrusion cooking is a hydrothermal process which may liberate phenolic acids and their derivatives from the cell walls or convert them from one form into another subject to technological processes and conditions (Khan

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and Ungar, 1986). Extrusion cooking also afects the stability of fat‑soluble vitamins such as vitamins A and E (Tiwari and Cummins, 2009), which are natural antioxidants in cereal grains. Zielinski et al. (2001) studied the efect of extrusion cooking (using a twin‑screw extruder) with a die temperature of 120–160–200°C, screw speed of 500 rev/ min, and mass fow rate at 225 g/min on barley cultivars and reported a 200–300% increase in the content of free phenolic acids and phenolic acids released from ester bonds, and a decrease of 91.4% and 81.8% in tocopherols and tocotrienols. Huth et al. (2000) reported an increase in enzyme‑resistant starch content in barley (2–3%) after extrusion. According to Altan et al. (2009), when barley four was subjected to heat treatment carried out at 140–160°C with a screw (150–200 rpm), a signifcant reduction in both antioxidant capacity (60–68%) and total phenolic content (46–60%) in barley extrudates was observed when compared with unprocessed barley four. Chang and Lin (2017) studied the physicochemical properties of barley extrudates using diferent extrusion parameters, feed moisture content, screw speed, and temperature, and concluded that the degree of gelatinization was increased at higher feed moisture content, lower screw speed, and higher extrusion temperature, whereas soluble dietary fbres were decreased after extrusion cooking up to 0.92%. Te lightness (L*) and total colour diference values were increased with an increase in screw speed and a decrease in feed moisture content in barley extrudates. Minimally processed foods confer more health benefts than processed foods (Shahidi, 2009). Roasting is a heat treatment of barley in hot sand at 280°C for 2 minutes, which causes the grains to expand and puf, ultimately splitting the husk. Te husk is then removed, and the roasted grains are ground to form barley four (Rashid et al., 2015). Pufng during roasting improves texture, crispness, and volume (Hoke et al., 2007). Tis processing also increases digestibility, colour, and favour and reduces the antinutritional factors and enhances consumer acceptability (Gahalawat and Sehagal, 1992). Rashid et al. (2015) evaluated the efect of sand roasting on the antioxidant activity of the extracted barley four and observed a decrease in total phenolic content. A study conducted by Randhir et

5.2.5.2 Roasting

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al. (2008) found that the decrease in total phenolic compounds may be due to the thermal degradation of heat‑sensitive phenolic compounds. Phenolic compounds are heat labile (Sharma and Gujral, 2011) and may be destroyed or have their molecular structure altered if they are subjected to temperatures above 80°C (Zielinski et al., 2001). Interestingly, Wofenden et al. (2002) reported an increase in antioxidant activity, which may be attributed to the formation of nonenzymatic browning products, especially melanoidins, at high temperatures. Lu et al. (2007) and Randhir et al. (2008) observed similar fndings for kilned barley and roasted barley. Honců et al. (2016) analyzed the changes in β‑glucan content in barley after extrusion and demonstrated that extrusion efectively increased the extraction rate of β‑glucan, which contributed to an increase in the nutritional value of the barley products. Köksel et al. (1999) investigated the efect of cooking processes on the levels of thiamine, ribofavin, and minerals (Fe, Cu, Zn, Mn, Ca, Mg), as well as phytic acid and β‑glucan and reported that β‑glucan increased and phytate content decreased, but cooking did not have a signifcant infuence on the content of Fe, Cu, Zn, or Mg. Cooking (regular boiling under atmospheric pressure) and roasting (125°C for 30 minutes) signifcantly increased total phenolic content and 2,2‑diphenyl‑1‑picrylhydrazyl (DPPH) radical scavenging activity, with roasting producing a higher increase. Cooked and roasted grains showed similar capacity to inhibit LDL oxidation (Gallegos‑Infante et al., 2010). 5.2.5.3 Cooking

5.3 Conclusions

Advancement in postharvest technology and value addition technology has provided opportunities for preparing and processing enhanced products which are acceptable to both urban and rural consumers. Even more, high‑quality products of barley are required for the beneft of all the stakeholders, from producers to farmers. So extensive research is required to develop improved barley food products that not only provide good health benefts but also have good taste, extended shelf life, appealing colour and are economically feasible for all population groups.

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Lachance, P., and Bauernfeind, J. 1991. Concepts and practices of nutrifying foods. In: Bauernfeind, J. C., and Lachance, P. A. (eds.), Nutrient Additions to Food. Trumball, CT: Food and Nutrition Press, 19–86. Lagassé, S. L., Hatcher, D. W., Dexter, J. E., Rossnagel, B. G., and Izydorczyk, M. S. 2006. Quality characteristics of fresh and dried white salted noodles enriched with four from hull‑less barley genotypes of diverse amylose content. Cereal Chemistry 83(2):202–210. Lee, S., and Inglett, G. E. 2006. Functional characterization of steam jet‑ cooked β‑glucan‑rich barley four as an oil barrier in frying batters. Journal of Food Science 71(6):E308–E313. Lemmens, E., Moroni, A. V., Pagand, J., Heirbaut, P., Ritala, A., Karlen, Y., Lê, K., den Broeck, H. C., Brouns, F. J. P. H., Brier, N., and Delcour, J. A. 2019. Impact of cereal seed sprouting on its nutritional and technological properties: A critical review. Comprehensive Reviews in Food Science and Food Safety 18(1):305–328. Leonard, W. H., and Martin, J. H. 1963. Barley. In: H. Warren, J. H. M. Leonard, Cereal Crops. New York: Macmillan, 478–543. Liu, K., and Moreau, R. 2008. Concentrations of functional lipids in abraded fractions of hulless barley and efect of storage. Journal of Food Science 73(7):C569–C576. Lu, J., Zhao, H., Chen, J., Fan, W., Dong, J., Kong, W., Sun, J., Cao, Y., and Cai, G. 2007. Evolution of phenolic compounds and antioxidant activity during malting. Journal of Agricultural and Food Chemistry 55(26):10994–11001. Madhujith, T., Izydorczyk, M., and Shahidi, F. 2006. Antioxidant properties of pearled barley fractions. Journal of Agricultural and Food Chemistry 54(9):3283–3289. Maillard, M. N., Soum, M. H., Boivin, P., and Berset, C. 1996. Antioxidant activity of barley and malt: Relationship with phenolic content. LWT – Food Science and Technology 29(3):238–244. Moreno, C. R., Fernández, P. C. R., Rodríguez, E. O. C., Carrillo, J. M., and Rochín, S. M. 2017. Changes in nutritional properties and bioactive compounds in cereals during extrusion cooking. In: S. Z. Qamar, Extrusion of Metals, Polymers and Food Products. UK: IntechOpen. Morrison, W. R. 1993. Cereal starch granule development and composition. In: P. R. Shewry, K. Stobart, Proceedings-Phytochemical Society of Europe. New York: Oxford University Press Inc., 35:175–175. Oghbaei, M., and Prakash, J. 2016. Efect of primary processing of cereals and legumes on its nutritional quality: A comprehensive review. Cogent Food and Agriculture 2(1):1136015. Osman, A. M., Coverdale, S. M., Cole, N., Hamilton, S. E., de Jersey, J., and Inkerman, P. A. 2002. Characterisation and assessment of the role of barley malt endoproteases during malting and mashing. Journal of the Institute of Brewing 108(1):62–67.

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Peleg, H., Naim, M., Zehavi, U., Rousef, R. L., and Nagy, S. 1992. Pathways of 4‑vinylguaiacol formation from ferulic acid in model solutions of orange juice. Journal of Agricultural and Food Chemistry 40(5):764–767. Pellegrini, N., Chiavaro, E., Gardana, C., Mazzeo, T., Contino, D., Gallo, M., Riso, P., Fogliano, V., and Porrini, M. 2010. Efect of diferent cooking methods on color, phytochemical concentration, and antioxidant capacity of raw and frozen Brassica vegetables. Journal of Agricultural and Food Chemistry 58(7):4310–4321. Pérez‑Conesa, D., García‑Alonso, J., García‑Valverde, V., Iniesta, M. D., Jacob, K., Sánchez‑Siles, L. M., Ros, G., and Periago, M. J. 2009. Changes in bioactive compounds and antioxidant activity during homogenization and thermal processing of tomato puree. Innovative Food Science and Emerging Technologies 10(2):179–188. Pinto, C., Rodriguez‑Galdon, B., Cestero, J. J., and Macias, P. 2018. Processed tomatoes improves the antioxidant status of carbon tetrachloride‑intoxicated rat tissues. European Food Research and Technology 244(10):1843–1852. Pisarnitskii, A. F., Egorov, I. A., and Egofarova, R. K. 1979. Formation of volatile phenols in cognac alcohols. Applied Biochemistry and Microbiology 15:103–109. Quinde, Z., Ullrich, S. E., and Baik, B. K. 2004. Genotypic variation in color and discoloration potential of barley‑based food products. Cereal Chemistry 81(6):752–758. Ragaee, S., Seetharaman, K., and Abdel‑Aal, E. S. M. 2014. Te impact of milling and thermal processing on phenolic compounds in cereal grains. Critical Reviews in Food Science and Nutrition 54(7):837–849. Ramberg, J., and McAnalley, B. 2002. From the farm to the kitchen table: A review of the nutrient losses in foods. Glycoscience and Nutrition 3:1–12. Randhir, R., Kwon, Y. I., and Shetty, K. 2008. Efect of thermal processing on phenolics, antioxidant activity and health‑relevant functionality of select grain sprouts and seedlings. Innovative Food Science and Emerging Technologies 9(3):355–364. Rashid, U., Gani, A., Shah, A., Ahmad, M., Baba, W. N., and Masoodi, F. A. 2015. Efect of sand roasting on the antioxidant and antiproliferative activity of barley (Hordeum vulgare). Nutrafoods 14(4):227–236. Rimsten, L., Haraldsson, A., Andersson, R., Alminger, M., Sandberg, A., and Åman, P. 2002. Efects of malting on β‑glucanase and phytase activity in barley grain. Journal of the Science of Food and Agriculture 82(8):904–912. Saleh, A. S., Zhang, Q ., Chen, J., and Shen, Q. 2013. Millet grains: Nutritional quality, processing, and potential health benefts. Comprehensive Reviews in Food Science and Food Safety 12(3):281–295. Sandhu, K. S., and Punia, S. 2017. Enhancement of bioactive compounds in barley cultivars by solid substrate fermentation. Journal of Food Measurement and Characterization 11(3):1355–1361.

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Sandhu, K. S., Punia, S., and Kaur, M. 2016. Efect of duration of solid state fermentation by Aspergillus awamorinakazawa on antioxidant properties of wheat cultivars. LWT – Food Science and Technology 71:323–328. Sandhu, K. S., Punia, S., and Kaur, M. 2017. Fermentation of cereals: A tool to enhance bioactive compounds. In: S. K. Gahlawat, R. K. Salar, P. Siwach, J. S. Duhan, S. Kumar, P. Kaur, Plant Biotechnology: Recent Advancements and Developments. Singapore: Springer, 157–170. Sapers, G. M. 1993. Browning of foods: Control by sulftes, antioxidants, and other means. Food Technology (USA) 47:75–84. Scheuring, J. F., and Rooney, L. W. 1979. A staining procedure to determine the extent of bran removal from pearled sorghum. Cereal Chemistry 56:545–548. Shahidi, F. 2009. Nutraceuticals and functional foods: Whole versus processed foods. Trends in Food Science and Technology 20(9):376–387. Sharma, P., and Gujral, H. S. 2010a. Milling behavior of hulled barley and its thermal and pasting properties. Journal of Food Engineering 97(3):329–334. Sharma, P., and Gujral, H. S. 2010b. Antioxidant and polyphenol oxidase activity of germinated barley and its milling fractions. Food Chemistry 120(3):673–678. Sharma, P., and Gujral, H. S. 2011. Efect of sand roasting and microwave cooking on antioxidant activity of barley. Food Research International 44(1):235–240. Sharma, P., and Gujral, H. S. 2013. Extrusion of hulled barley afecting β‑glucan and properties of extrudates. Food and Bioprocess Technology 6(6):1374–1389. Sharma, P., Gujral, H. S., and Singh, B. 2012. Antioxidant activity of barley as afected by extrusion cooking. Food Chemistry 131(4):1406–1413. Singh, A., and Sharma, S. 2017. Bioactive components and functional properties of biologically activated cereal grains: A bibliographic review. Critical Reviews in Food Science and Nutrition 57(14):3051–3071. Singh, A. K., Rehal, J., Kaur, A., and Jyot, G. 2015. Enhancement of attributes of cereals by germination and fermentation: A review. Critical Reviews in Food Science and Nutrition 55(11):1575–1589. Singhania, R. R., Patel, A. K., Soccol, C. R., and Pandey, A. 2009. Recent advances in solid‑state fermentation. Biochemical Engineering Journal 44(1):13–18. Smith, A. C., and Singh, N. 1996. New applications of extrusion technology. Indian Food Industry 15:14–23. Steinke, R. D., and Paulson, M. C. 1964. Phenols from grain, production of steam‑volatile phenols during cooking and alcoholic fermentation of grain. Journal of Agricultural and Food Chemistry 12(4):381–387. Teixeira, C., Nyman, M., Andersson, R., and Alminger, M. 2016. Efects of variety and steeping conditions on some barley components associated with colonic health. Journal of the Science of Food and Agriculture 96(14):4821–4827.

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6 S TARCH Structure, Properties, and Applications

6.1 Introduction

As a comprehensive nutritive cereal, barley contains about 80% complex carbohydrates, 3.7–7.7% β‑glucans, 11.5–14.2% proteins, 4.7–6.8% lipids, and 1.8–2.4% ash (Li et al., 2001). Among all the nutrients, starch forms the largest component of the kernel and accounts for 70% of the total dry weight (Asare et al., 2011). Starch molecules are the polymers of anhydrous glucose units which are typically accumulated in the unique and independent granules (Zia‑ud‑ Din et al., 2017) and undeniably the most important polysaccharide in the human diet. It is second to cellulose in terms of abundance of organic compounds in the biosphere (Ashogbon, 2017). Amylose and amylopectin are the main carbohydrate components of the starch granules, and the physicochemical and functional properties of starch depend on the amylose and amylopectin starch content, the amylose/ amylopectin ratio, and the inner structure of starch granules (Li et al., 2014). Starch is a major component of various foods, and its properties and reactions with other food components, mainly water and lipids, are signifcant concerns in the food industry and for human nutrition (Copeland et al., 2009). 6.2 Starch Isolation and Purifcation

Traditionally, starch is isolated from barley through dry‑ and wet‑milling methods (Gao et al., 2009). Generally, the wet‑milling methods used to isolate starch involve grain steeping and blending, followed by screening, deproteinization, and recovery of starch by centrifugation. Te isolation methodologies difer with respect to the media in which 97

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the grains are steeped (water, acid, and mercuric chloride) prior to milling, the isolation technique (dry milling, wet milling, dry milling followed by wet milling), the enzyme source used for increasing the starch yield (protease, cellulose, xylanase, lichenase, glucanase), screen size, centrifugal speed, and the chemicals used for protein removal (sodium hydroxide, caesium chloride) (Vasanthan and Hoover, 2009). Barley grain is rich in proteins, soluble sugar, and β‑glucans, which are highly viscous in aqueous solutions and strongly bind to the starch (Sharma and Tejinder, 2014); this impairs the process of isolating the starch from barley. Wu et al. (2014) isolated starch with sodium hydroxide to eliminate the infuence of β‑glucans. Researchers have used an aqueous mercuric chloride solution (0.01 M) for steeping, a nylon mesh (75 µm) for screening, and repeated toluene washing (Greenwood and Tomson, 1959; Adkins and Greenwood, 1966). McDonald and Stark 1988) used acid (pH = 2) steeping of cracked grains followed by neutralization, gentle grinding, and screening through a nylon mesh (75 µm). Tester and Morrison (1992) isolated starch from waxy and nonwaxy barley grains by steeping in water, macerating, and then purifying by centrifugation in the presence of caesium chloride (CsCl). Li et al. (2001) isolated starches from 10 cultivars of hull‑less barley grains following the wet‑milling procedure and reported average yields and extraction efciencies of 44.4% and 70.9%, respectively. A few advanced methods of the starch isolation process were developed which resulted in improved yield and/or starch purity. A wheat gluten‑based nondestructive method to isolate starch from various fours, including barley four, has been developed and patented (Al‑Hakkak and Al‑Hakkak, 2007). Further, Gao et al. (2009) developed an aqueous alcohol‑based enzymatic method to mask the impact of high viscosity due to the presence of endogenous β‑glucans. Using this method, they isolated starches from three hull‑less barley genotypes with waxy, normal, and high‑amylose‑content, and the yields ranged from 22.5% to 39.2%, and the purity was over 98.3%. Rittenauer et al. (2016) used dry milling, microsieving, and density gradient centrifugation in their study; after crushing the kernels, the granules were dispersed in water, and then the suspension was microsieved and centrifuged to obtain crude starch. Te crude starch was dispersed and washed in 80% CsCl solution before washing with water to further purify the starch.

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6.3 Chemical Structure

Te starch granule is a semicrystalline system, consisting of crystalline and amorphous regions. Amylose (a major factor afecting starch quality, which varies from 0% to 40% depending on the variety) and amylopectin are the main carbohydrate components of the starch granule. Amylose is linear with the glucosyl units being connected by α‑(1−4)‑linkages. A few branches of α‑(1−6)‑linkages may exist in amylose. Amylopectin has a highly branched structure, in which the glucosyl units are branched by α‑(1−6)‑bonds (Bertoft, 2004). Te crystallinity is exclusively associated with the amylopectin component, while the amorphous regions mainly represent amylose (Zobel, 1988a, 1988b). Amylose is an essentially linear α‑1,4‑D‑glucan chain with molecular weight and degree of polymerization (DP) in the range of 105–106 Da and 700–5000 anhydroglucose units, respectively. Amylopectin is highly branched and composed of thousands of linear α‑1,4‑D glucan unit chains and 4–5.5% of α‑1, 6‑glucosidic bonds (Hizukuri et al., 1981). Te average chain length and average molecular weight of amylopectin are 17–31 anhydroglucose units (Hizukuri et al., 1983) and 7.0 × 107–5.7 × 109 Da (Yoo and Jane, 2002), respectively. Liu et al. (2019) reported a molecular weight of 8.796 × 107 g/mol, and the molecular fractions were mainly in the range of >4 × 107 g/mol for barley starch. Bello‑Perez et al. (2009) reported a weight‑averaged molecular weight of 1.03 × 105 and 1.15 × 106 g/mol for barley amylose and amylopectin, respectively. Simsek et al. (2013) used a high‑performance size‑exclusion refractive index (HPSEC‑RI) with dextran standards and reported that the weight‑averaged molecular weight of barley amylose was 1.43 × 105 g/mol. In another report, the weight‑ averaged molecular weight of amylopectin (waxy barley starch) was 2.044 × 108 g/mol, as measured by a high‑performance size‑exclusion‑ multiangle light scattering‑refractive index (HPSEC‑MALLS‑RI) with pullulan standards (Chung et al., 2008), and 6.85 × 106 g/mol with dextran standards (Simsek et al., 2013). Te number‑averaged degree of polymerization, average chain length, average number of chains per molecule, and weight‑averaged molecular weight of barley amylose are in the range 940–1000 (Takeda et al., 1999; Yoshimoto

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et al., 2000), 115–530 (Tang et al., 2001, 2002), 6–10 (Tang et al., 2002), and 2.73 × 106 –5.67 × 106 (You and Izydorczyk, 2002), respectively. Te β‑amylolysis limit, iodine afnity, and the limiting viscosity number are in the range 70–95%, 17.4–20%, and 240–391 g/mL, respectively (Greenwood and Tomson, 1959; Banks et al., 1973; Morrison et al., 1993). Song and Jane (2000) and Suh et al. (2004) reported that in barley starches, the proportions of DP 6–9, DP 6–12, DP 13–24, DP 25–36, and DP ≥37 are in the range 3.1– 5.3%, 16.5–21.6%, 40.9–47.5%, 14.6–17.9%, and 17.8–23.7%, respectively. Song and Jane (2000) reported that normal starch contained the highest DP followed by high‑amylose and waxy starches. 6.4 Chemical Composition

Signifcant variations were found in the chemical compositions (amylose, lipid, proteins, ash, and phosphorus‑containing compounds) of normal, waxy, and high‑amylose barley starches (Table 6.1). Waxy and high‑amylose genotypes are developed by genetic means (Shaik et al., 2016). Te amylose content signifcantly afects the functional properties of barley starch: starch with a high amylose content shows greater susceptibility to retrogradation, and its pastes are more elastic (Bello‑Perez et al., 2010). Various methods have been employed for measuring the amylose content including iodine‑binding amperometry, iodine‑binding spectrophotometry and potentiometry, concanavalin A‑precipitation, and gel‑permeation chromatography (GPC) of whole/debranched starch. Regina et al. (2010) adopted two methods, iodine‑binding spectrophotometry and GPC, for measuring the amylose content and presented diferent results for the same type of barley starch; for spectrophotometry, the amylose content was found in the range of 28.5–89.3%, and the values were 22.7–76.2% for the GPC method. Gujral et al. (2013) measured the amylose content by iodine‑binding spectrophotometry and reported values in the range of 21.0–28.3%. Te amylose content of starch is also related to the granule size and is afected by growth conditions (Källman et al., 2015). Tey reported that as the endosperm of barley develops, the amylose content also increases. Pycia et al. (2015) reported an amylose content of 19.6–25.2% in barley starches. Te amylose content of a normal

59.7–61.9 98.58–98.82 –

–

58.1–68.5 99.81–99.39 – –

86.67–98.79 – – – – – 90–97.95 72.2 60 41.40 99.25–99.71 – –

STARCH YIELD (%)

26.35–28.12 22.10–23.32 19–22.1 25.3–30.1 0–4.5 2.18–6.02 0.00–3.88 1.8–3.6 2.1–8. 18.2–24.1 38.4–44.1 38–40.8 39.45–41.28 27.74–31.04

21.80–26.57 23.7 22.7 24–26.9 17.6–29.3 19.6–25.2 22.72–27.49 25.8 28.5

AMYLOSE CONTENT (%)

– – –

–

– – – –

64.86–77.88 – – – – – 65.89–72.64 – – – – – –

AMYLOPECTIN (%)

Starch Yield and the Chemical Composition of Barley Starch

Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal wild type Normal wild type Waxy Waxy Waxy Waxy Waxy High amylose High amylose High amylose High amylose High amylose

TYPE

Table 6.1

– 0.18–0.30 –

–

– 0.04–0.17 – 0.06–0.15

0.21–0.73 – 0–64 – – 0.50–1.26 0.31–0.45 – – – 0.07–0.19 – 0.2–0.4

PROTEINS (%)

0.08–0.09 0.04–0.14

1.0–1.7

0.3–0.5

0.03–0.05 0.0.4–0.05

– – 0.25 0.41–0.45 – 0.10–0.61 0.01–0.02 – – – 0.14–0.15 0.04–0.06 – 0.7–1.2

FATS (%)

– 0.38–0.40 0.21–0.30

–

0.16–0.21 0.10–0.16 –

– – 0.30 – – – – – – – 0.29–0.30 0.09–0.12 –

ASH (%)

Fan et al. (2019) Liu et al. (2019) Kaur et al. (2018) Yangcheng et al. (2016) Kallman et al. (2015) Pycia et al. (2015) Li et al. (2014) Asare et al. (2011) Regina et al. (2010) Gupta et al. (2009) Gao et al. (2009) Waduge et al. (2006) Ellis et al. (1998) Morrison et al. (1984) Asare et al. (2011) Gao et al. (2009) Waduge et al. (2006) Ellis et al. (1998) Morrison et al. (1984) Ellis et al. (1998) Morrison et al. (1984) Asare et al. (2011) Gao et al. (2009) Waduge et al. (2006)

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genotype increased from 17.6% to 29.3% from 9 to 24 days after fowering (Källman et al., 2015). Fan et al. (2019) reported amylose, amylopectin, and protein contents of 21.80–26.57%, 64.86–77.88%, and 0.21–0.73%, respectively, for barley starch with a starch yield of 86.67–98.79%. Hoover (2001) stated that if starch is not defatted prior to amylose estimation, it underestimates the amylose content. Te solvent extraction method used for removing lipids also increases the amylose content (Gao et al., 2009). Te quantifcation method also afects the fat content of starch. Free lipids may be washed out by the chloroform and methanol solvent, whereas bound lipids can be obtained by using hot 1‑propanol and water (Gao et al., 2009). Tey reported values of 0.05–0.15% and 0.12–0.85% for free and bound lipids, for six genotypes. Te phosphate groups of starch may afect the physicochemical properties (Shaik et al., 2016). Te content of the phosphate groups of starch increases in the developing endosperm (Borén et al., 2008). Nevertheless, normal barley genotypes tend to have a low phosphorus content in the starch (Gao et al., 2009). 6.5 Granular Morphology

Te morphological characteristics of cereal starches are examined using a scanning electron microscope (SEM), light microscope, transmission electron microscope, polarized light microscope, and confocal laser scanning microscope. Te morphological characteristics of starches from diferent plant sources vary with the genotype and depending on the biological origin. Common cereals such as wheat, barley, and rye contain two types of starch granules: (1) A‑type, which is lenticular‑shaped and large‑sized, and (2) B‑type, which is spherical‑shaped and small‑sized (Vamadevan and Bertoft, 2015). Bimodal distribution, large lenticular granules (disk shaped, 10–30 µm), and smaller irregularly shaped (spherical, ≤6 µm) granules (Vasanthan and Hoover, 2009) were also reported in barley starch. Te shapes and sizes of barley starch granules are reported in Table 6.2 and Figure 6.1. Large granules constitute 10–20% of the total number of starch granules and 85–90% of the weight of the total starch mass; small granules constitute 80–90% by number and

Oval shape Smooth; however, some grooves when observed under ×4000 magnifcation Large (A-type), small (B-type) granules; large granules = fat ovoid shape and uneven surface, small granules = a spherical shape Small- and large-sized granules with lenticular and irregular shapes Elliptical, oval, disks to irregular shapes Small pores

Normal Normal

–

Large pores were present on the surface of spherical and lenticular granules of the waxy starches Small pores –

Waxy

Waxy

High-amylose High-amylose

A-type: disk-shaped, B-type: lenticular

Normal Normal Normal Wild type

Normal

Normal

SHAPE OF STARCH GRANULES

Morphology of Starch Granules

TYPE

Table 6.2

– A-type: 15–32 B-type: 2–3

10–30 – 2–30 A-type: 10–25 B-type: 5 A-type: 10–25 B- type: 5 –

–

–

17.18–18.56 6.96–25.1

SIZE (βM)

A+B –

A

–

A A+B – –

A

A

A –

X-RAY PATTERN

– –

–

–

10.72–43.21 – – –

26.67

25.3

22.30–24.85

RELATIVE CRYSTALLINITY (%)

Waduge et al. (2006) Ellis et al. (1998)

Waduge et al. (2006)

Ellis et al. (1998)

Li et al. (2014) Waduge et al. (2006) Li et al. (2004) Ellis et al. (1998)

El Halal et al. (2015)

Liu et al. (2019); Yangcheng et al. (2016)

Fan et al. (2019) Mehfooz et al. (2019)

REFERENCES

S T RU C T URE , P R O P ER TIE S, A N D A P P LI C ATI O NS

10 3

10 4

Figure 6.1

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Scanning electron micrograph of barley starch.

10–15% by weight (MacGregor and Fincher, 1993). SEM shows the presence of pin holes on the granular surface of high‑amylose (up to 0.9 µm in diameter) and normal (≤0.9 µm) barley starches (Li et al., 2001). Li et al. (2001) reported granule sizes of 2–30 μm, whereas Li et al. (2014) reported values that ranged from 10 to 30 μm. Li et al. (2014) and Li et al. (2004) reported that the surface of barley granules appeared to be smooth, and the shapes varied from elliptical, oval, disk, to irregular. Li et al. (2014) used confocal scanning microscopy for analyzing the granular morphology and reported the appearance of a growth ring and internal cavities (hilum) in barley starch granules. Transmission electron microscopy shows the presence of internal channels in both waxy and normal starch granules (Li et al., 2004). Waduge et al. (2006) examined the morphology of hull‑less barley starch granules using SEM and reported a mixture of large (spherical, disk, and lenticular shaped) granules for the waxy type and small (irregularly shaped) granules for the normal and high‑amylose types, and most of these granules were present as clusters. Te anisotropic structure, including crystalline regions and amorphous regions in the starch granules, results in a Maltese cross in starch granules when exposed to polarized light (Zhang et al., 2014). Sivak and Preiss (1998) studied the birefringence patterns of starch granules under polarized light and reported that within the starch granules amylopectin crystallites are arranged radially at right angles to the surface with their single reducing end group arranged toward the hilum. Li et

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10 5

al. (2014) reported that all starches exhibited a typical “Maltese cross” under polarized light. Tey reported both strong and weak birefringence patterns in barley starches, and the weak birefringence patterns of barley starch granules indicate that the arrangements of the amylopectin double helices within the crystalline lamella are relatively loose or not fairly recognized. Liu et al. (2019) reported that barley starch showed a bright birefringence cross in the centre of granules. 6.6 Swelling Power and Solubility

One of the most important structural characteristics of starch is that it passes through several diferent stages from water absorption to granule disintegration. Water absorption and consequent swelling of the starch granule contribute to amylopectin‑amylose phase separation and crystallinity loss, which in turn promotes the leaching of amylose to the intergranular space (Conde‑Petit et al., 2001). At the molecular level, the swelling power (SP) and the solubility of the starch granule is infuenced by the amylose to amylopectin ratio, the molecular mass of each fraction, the degree of branching, the conformation length of the outer branch of amylopectin, and the presence of other components such as lipids and proteins (Mauro, 1996). Te swelling factor and swelling power (SP) represent the swelling property, whereas the leaching of amylose, solubility, and the water solubility index (WSI) represent the solubility (Pycia et al., 2015; Kong et al., 2016). Te SP and solubility increased considerably in the temperature ranges of 50–60°C and 80–90°C, respectively. During the heating process, the starch granules swell, the crystalline structures in starches are disrupted, and the water molecules are linked to the hydroxyl group of amylose and amylopectin by hydrogen bonding, resulting in an increase in solubility (Li et al., 2014). Kong et al. (2016) reported an SP and WSI of 12.8–19.9 g/g and 12.7–23.7% at 95°C for 14 genotypes of barley. Gupta et al. (2009) reported an SP and solubility of 10.43 g/g and 18.40 for native barley starch. Ratnayake et al. (2002) explained that the solubility is primarily infuenced by the amylose content, while amylopectin infuences the SP. Waxy starch exhibited the highest degree of swelling, supporting the idea that reduced amylose content relates to greater swelling. Because the swelling behaviour of cereals has

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been related to amylopectin (Tester and Morrison, 1990), the high SP suggested a less rigid granular structure of waxy starch compared with that of nonwaxy starches. 6.7 Starch Crystallinity

X‑ray difraction (XRD) is used to study the presence and characteristics of the crystalline structure of the starch granules. Starch granules possess a semicrystalline structure corresponding to diferent polymorphic forms, and based on this starch can be classifed into three types, namely A, B, and C (Buléon et al., 1998). Te arrangement of the amylopectin helices is supposed to be responsible for starch crystallinity, whereas amylose is associated with amorphous regions (Singh et al., 2006; Zobel, 1988a). Te crystalline parts of starch always show sharp peaks, whereas the amorphous parts of starch have dispersive peaks (Gernat et al., 1990). On the basis of these peaks, starch is diferentiated into A, B, and C types. Te diferences in the difraction patterns may be due to diferent growth conditions and the maturity of the parent plant at the time of harvest, biological origin, and the amylose and amylopectin content (Zhou et al., 2010). Te XRD pattern of barley starch is reported in Figure 6.2. Li et al. (2014) reported that barley starches exhibited typical A‑type crystalline packing arrangements with strong refections at 2 of about 15°, 17°, 18°, 20°, and 23°, corresponding to d‑spacings of about 5.70, 5.10, 4.90, 4.40, and 3.80 Å, respectively. As reported by Fan et al. (2019) and El‑Halal et al. (2015), barley starches exhibited typical A‑type crystalline packing arrangements and presented strong refections at 2 of about 15°, 17°, 18°, 20°, and 23°. 6.8 Pasting Properties

Te functionality and quality of starchy cereal‑based products mainly depend on the starch properties and characteristics (Delcour et al., 2010). Te pasting attributes are useful in the choice of the product depending on its use in the industry as a binder, thickener, or for any other purpose. Te selection process is also related to the viscosity of the gel formed during and after heating (Kaur et al., 2018). Te pasting properties of starch are afected by the amylose and lipid content and by the branch

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Figure 6.2

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X‑ray diffraction spectra of barley starch.

chain length distribution of amylopectin (Gujral et al., 2013). Te pasting characteristics of starches may be measured using an amylograph, such as the Brabender Amylograph and the Rapid Visco Analyzer (RVA) (Sandhu and Singh, 2005), or a dynamic rheometer (Punia et al., 2019a,68 2019b). Of these, RVA is the most commonly used method in the viscosity measurement, primarily because of its advantages of fast determination and the smaller sample sizes required (Cozzolino, 2016). Te studies on the pasting properties listed in Table 6.3 used diferent experimental conditions, diferent instruments, and diferent starch concentrations. Pasting is a complex phenomenon which specifcally refers to the changes in starch after post‑gelatinization heating (Wani et al., 2016). Peak viscosity (PV) indicates the maximum swelling of the starch granule prior to disintegration (Liu et al., 2006). Te breakdown viscosity (BV) is a measurement of the degree of disintegration of the granules; when the swollen granules are disrupted, amylose molecules leach out into the solution during the breakdown process (Kaur et al., 2007). It is measured as the diference between the PV and the trough viscosity (TV). Te fnal viscosity (FV) determines the cooked paste’s stability, and FV increases due to the aggregation of the amylose molecules upon cooling. Li et al. (2014) examined the pasting profles of

Pasting Properties of Starches

RVA (RVA-3D, Newport Scientifc, Narrabeen, Australia) Modular Compact Rheometer (MCR302, Anton Paar GmbH, Austria) Rapid Visco Analyzer (Newport Scientifc, Sydney, Australia) Rapid Visco Analyzer (RVA-4, Newport Scientifc, Australia) Rapid Visco Analyzer (TecMaster, Perten Instruments AB, Sweden) RVA model Super-4 (Newport Scientifc, Pty Ltd, Australia) Rapid Visco Analyzer (RVA-4, Newport Scientifc, Warriewood, Australia) Rapid Visco Analyzer (RVA) (model 3D; Newport Scientifc Ltd, Sydney, Australia)

INSTRUMENT USED

Table 6.3

2801–4478 238.4 138.9–153.9 267.8 133–230 2971–3641 1913–2622 324.33

6% 2% 3g 5g 3g 3g 6–8%

PV

3g

STARCH (%/G)

252.75

1065–1600

2253–2844

101–145

215.1

–

60.4

2274–3467

TV

71.58

652–1139

474–876

32–85

52.7

–

178

527–1512

BD

422.33

1955–2854

3094–4320

224–411

295.8

–

476.0

2735–5140

FV

RVU

cP

cP

mPa.s

RVU

RVU

cP

cP

UNIT

77.75

75.8–84.6

50.25–84.35

86.5–90.9

85.6

92.5–93.2

67.0

71.6–89.8

PT (°C)

Gujral et al. (2013) Gupta et al. (2009)

Li et al. (2014)

Yangcheng et al. (2016) El-Halal et al. (2015) Pycia et al. (2015)

Liu et al. (2019)

Fan et al. (2019)

REFERENCES

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seven naked barley starches and reported PV, TV, BV, and FV of 2977– 3641, 2253–2844, 474–876, and 3094–4320 cP, respectively. Signifcant variations were found for the pasting profles of barley starches (Table 6.3 and Figure 6.3). A study conducted by Fan et al. (2019) compared the pasting properties of starches from four barley varieties and reported PV, TV, BV, and FV in the range of 2801–4478, 274–3467, 527–1512, 2735–5140 cP, respectively. Te diferences in the pasting properties of barley starches may be due to starch purity, amylose and amylopectin content, their ratio, granule size, the interactions between the double helices, and their stability during the heating and shearing processes (Li et al., 2014). 6.9 Flow and Dynamic Oscillatory Analysis

Te increase in the viscosity of the starch system, which is observed during starch pasting, results from the many structural changes of

Figure 6.3

Pasting graph of barley starch.

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starch, such as nonreversible starch granule swelling and amylose leaching from starch granules. Typical starch paste exhibits properties of a non‑Newtonian, shear thinning fuid (Pycia et al., 2015). Signifcant (p < 0.05) diferences in the rheological properties of barley starch suspensions were observed. Te most common method of studying the viscoelastic properties of starch is by a dynamic rheometer. All starches studied showed the values for G′′ less than G′. tan δ (G′′/G′) for all the starches studies was less than 1, indicating their elastic behaviour. Pycia et al. (2015) studied the fow behaviour of barley starches. In order to describe the variations in the rheological properties of the samples under steady shear, the experimental curves were described by the power law equation: t = K × gn

where τ – shear stress [Pa], K – consistency coefcient [Pa·sn], γ˙ – shear rate [s−1], and n – fow behaviour index. n values of starch pastes were less than 1 (0.29–0.38), indicating the shear thinning behaviour of starch pastes. To characterize fuids and semifuids, the n value is mostly used; the behaviour of the pastes with an n value of 1 indicates a Newtonian fuid, n value of less than 1 shows shear thinning, and n value of greater than 1 indicates shear thinning fuid behaviour (Lee and Chang, 2015). Bhandari et al. (2002) attributed shear thinning behaviour to a higher amount of breakage of the intra‑ and intermolecular associative bonding system in starch network micelles due to shearing at high rates. Te frequency dependencies of the storage modulus (Gʹ) and loss modulus (G″) provide signifcantly valuable information about the gel structure (Kaur et al., 2008). In addition to Gʹ and G″, the loss tangent (G″/Gʹ) was observed to refect the dynamic elastic nature of the gels, indicating the relative measure of the associated energy loss versus the energy stored per deformation cycle (Toker et al., 2013). Pycia et al. (2015) analyzed the starch gel mechanical spectra and reported that values of G′ were greater than those of G″, which depicts the domination of elastic properties over viscous properties.

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6.10 Termal Properties

Te thermal properties of starch are afected by many factors, such as the size and shape of the starch granules, the phosphorus content, the degree of starch crystallinity, and the length of the amylopectin chains (Singh et al., 2007). Starch, when heated in the presence of excess water, undergoes an order‑disorder phase transition called gelatinization over a temperature range characteristic of the starch source (Hoover et al., 2010). Te endothermic peak recorded by differential scanning calorimetry (DSC) is linked with the gelatinization of starch, which refects the loss of the double‑helical structure of the starch granules (Cooke and Gidley, 1992). Te thermal properties of barley starches are shown in Table 6.4. Te starch gelatinization temperature is a measure of the cooking quality of starch and an important parameter in food processing; starches with low gelatinization temperatures have good cooking quality (Waters et al., 2006). Te diferences in gelatinization temperatures may be attributed to the diferences in amylose content, size, form, and distribution of starch granules and to the internal arrangement of starch fractions within the granule (Singh et al., 2004). Bao et al. (2009) reported that the thermal properties of starch are correlated with the chain length distribution and the average chain length of the amylopectin molecules. Te lower ΔHgel suggests a lower percentage of organized arrangements or a lower stability of the crystals (Chiotelli and Meste, 2002). According to Jenkins (1994), gelatinization in excess water is primarily a swelling‑driven process. Tis swelling acts to destabilize the amylopectin crystallites within the crystalline lamellae, which are ripped apart (smaller crystallites are destroyed frst) during the process (Ratnayake et al., 2002). Krueger et al. (1987) reported that the higher the amylopectin content of the starch, the narrower was the temperature range of gelatinization. Te ΔHgel refected primarily the loss of a molecular double‑helical order (Cooke and Gidley, 1992). Tp gives the measure of the crystallite quality (double helix length). Te enthalpy of gelatinization (ΔHgel) gives an overall measure of the crystallinity (quality and quantity) and is an indicator of the loss of the molecular order within the granule (Cooke and Gidley, 1992; Tester and Morrison, 1990). Te gelatinization transition

DSC

INSTRUMENT

Table 6.4

10°C/min – 10°C/min 10°C/min 10°C/min

HEATING RATE (°C/MIN) 63.96 – 61.2–63 63.28 66.1–73.7 63 61.66 65.1 59.48 59.4–71.9 62.2–72.7 64.6–85

TP (°C) 72.02 63.1–65.4 67.1–68.7 67.43 71.9–73.7 69.8 65.42 70.2 77.20 63.5–76.7 67.7–79.2 73.7– 104.6

TC (°C)

GELATINIZATION PARAMETERS 59.48 54.1–56.1 56.5–58.5 59.49 61.1–62.6 59.4 58.33 60.1 55.52 53.9–66.9 57.2–69.2 54.1–69.2

TO (°C)

Thermal Properties of Barley Starches

10.26 10.1–10.9 6.49–9.61 8.92 6.7–9 5.4 7.46 4.9 7.65 11.43–13.21 12.86–14.29 10.59–23

ΔHgel (J/G)

Mehfooz et al. (2019) Yangcheng et al. (2016) Pycia et al. (2015) El Halal et al. (2015) Kim et al. (2015) Regina et al. (2010) Li et al. (2014) Gujral et al. (2013) García et al. (2012) Normal type, Gao et al. (2009) Waxy type, Gao et al. (2009) High amylose type, Gao et al. (2009)

REFERENCES

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temperatures To, Tp, Tc, and ΔHgel have been known to be infuenced by the molecular architecture of the crystalline region (Wani et al., 2016). Te starch to water ratio and the scanning rate of temperature infuence the gelatinization parameters recorded by DSC (Zhu, 2014). Pycia et al. (2015) reported that the transition temperatures (To, Tp, and Tc) of barley starches from diferent cultivars varied in the range of 56.5–58.5°C, 61.2–63°C, and 67.1–68.7°C, respectively. Gujral et al. (2013) reported To, Tp, and (Tc) in the range of 59.08–62.0°C, 63.56–68.3°C, and 68.65–74.71°C, respectively, for barley starches. Tey observed that the enthalpy of gelatinization ranged from 3.69 to 4.87 J/g. Cooke and Gidley (1992) reported that the enthalpy of gelatinization refects the loss of the molecular order. Regina et al. (2010) also reported the gelatinization properties, To, Tp, Tc, and ΔHgel, of barley millet starch to be 59.4°C, 63°C, 69.8°C, and 5.4 J/g, respectively. Li et al. (2001) reported that the gelatinization enthalpy of waxy barley starch decreased with a decrease in the granule size of starch. Moreover, Yasui et al. (2002) reported that starch from waxy barley was characterized by higher gelatinization temperatures and higher gelatinization enthalpy as compared to normal barley starch. 6.11 In Vitro Digestibility

Te glycaemic index (GI) concept is a tool for ranking foods with respect to their blood glucose raising potential (Kaur and Sandhu, 2010). GI is most appropriately used to compare foods within a category of foods. In general, digestible starches are hydrolyzed by the enzymes in the small intestine to yield free glucose, which is then absorbed. Starch digestibility in the human digestive system can vary from rapid digestion to indigestibility (Lehmann and Robin, 2007). Starch digestion is an important metabolic response, and the rate and extent of digestibility in the small intestine determines the eventual glucose level in the blood (Jenkins et al., 1982). On the basis of the rate of release of glucose in the bloodstream and its gastrointestinal absorption, starches have been categorized into rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS). RDS is defned as the starch fraction hydrolyzed digested in vitro within 20 minutes, SDS is digested between 20 and 120 minutes,

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and RS is the starch not hydrolyzed after 120 minutes of incubation (Englyst et al., 1992). After ingestion, a sudden rise in blood glucose is caused by the RDS fraction, and SDS is that fraction of starch which is completely digested in the small intestine at a slower rate when compared with RDS. SDS prolongs the release of glucose, thus preventing hyperglycaemia‑related diseases (Mei et al., 2015). RS is the sum of starch and its derivatives that are not digested in the small intestine of healthy individuals (Asp, 1992). Depending on the nature of inaccessibility, there are fve classes of RS: RS1, RS2, RS3, RS4, and RS5 (Birt et al., 2013). RS1 is found in whole or coarsely ground grain where starch may be encased inside cells or in a strong protein matrix; RS2 consists of raw starch granules that resist amylase digestion, and RS3 is retrograded or recrystallized starch. RS4 is chemically modifed starch with nonnative chemical bonds formed, and RS5 is amylose complexed with lipid, usually a fatty acid (Zhao et al., 2011). Asare et al. (2011) reported that the enzymatic hydrolysis rate in the starch samples followed the order waxy > normal > increased amylose, and they concluded that the RDS increased with a decrease in amylose concentration. Liu et al. (2019) reported that the RDS, SDS, and RS contents of native highland barley starch were 96.19%, 1.54%, and 2.27%, respectively. 6.12 Applications

Barley starch is of consistent quality and is ideal for various industrial uses. Te large variations reported in the composition, structures, and physicochemical properties of both native and modifed barley starches provide a basis for understanding the variations in the quality of barley‑based products as well as for their diverse uses in food and nonfood industries. Tey may have the potential to be used as feed ingredients and adhesives in paperboard; for clay removal in potash mining; for sizing and coating in paper production; for the production of alcohol, dextrins, sweeteners, and lactic acid; and for encapsulation of functional food ingredients (Vasanthan and Hoover, 2009). Te recently reported uses of barley starch notably include the production of thermoplastics and flms using amylose‑only genotypes and modifed starches, decreasing the glycaemic indexes of foods

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by high‑amylose barley genotypes and retarding the staling process of bread using waxy and heated barley four (Sagnelli et al., 2016; Purhagen et al., 2011; King et al., 2008). Terefore, it seems that barley starch has great potential to complement or compete with other commercially important starches in some applications. However, the wide diversity in the starch properties of barley genotypes should be better exploited for various uses. 6.13 Conclusions

Tis chapter represents the diversity in the physicochemical, structural, morphological, pasting, and thermal properties of barley starches. Barley starches showed signifcant diferences in characteristic behaviour, suggesting their applications for broader use. Te wide range of chemical compositions, structures, and functionalities of barley starch, as summarized in this chapter, provides a strong basis for its innovative applications in the food and other industries.

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7 S TARCH M O D IFICATIONS Physical, Chemical, and Enzymatic

7.1 Introduction

Te attractiveness of starch usage in food and nonfood industries may be due to its cheapness, abundance, biodegradability, and nontoxic nature (Ashogbon and Akintayo, 2014). Te use of starch is common in soups, confectionary, dairy, bakery items, sauces, dips, gravies, snacks, batters, coatings, and meat products (Kaur et al., 2012). Starch plays a pivotal role in texture, viscosity, gel formation, adhesion, binding, moisture retention, flm formation, and homogeneity of food products. However, native starches have some limitations for industrial uses as starches in their native form do not have physical and chemical properties suitable for certain types of processing. Most native starches are limited in their direct application because they are unstable with respect to changes in temperature, pH, and shear forces. Additionally, some starch granules are inert, insoluble in water at room temperature, highly resistant to enzymatic hydrolysis, and consequently lack functional properties. Native starches are insoluble in water, easily retrograde with associated syneresis, and most signifcantly gels and pastes produced by native starch are unstable at high temperature, pH, and mechanical stress and show a strong tendency for decomposition and retrogradation (Berski et al., 2011). Due to these inherent native starch inadequacies, there is a need for modifcation to improve the functional and physicochemical properties to suit industrial applications. Native starches are often modifed to develop specifc properties such as solubility, texture, adhesion, and tolerance to the heating temperatures used in industrial processes (Sweedman et al., 2013). Modifcation of starches can be broadly divided into physical, chemical, and enzymatic, or their combinations can be called dual 12 3

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modifcation (Deka and Sit, 2016; El Halal et al., 2015; Majzoobi et al., 2015; Ashogbon and Akintayo, 2014) (Figure 7.1). Physical methods involve the use of heat and moisture; chemical modifcations introduce functional groups into the starch molecule using derivatization reactions (e.g., etherifcation, esterifcation, cross‑linking) or involve breakdown reactions (e.g., hydrolysis and oxidation) (Singh et al., 2007); and enzymatic modifcation involves enzymes (Tables 7.1 and 7.2). 7.2 Physical Modifcation

Food industries have started showing interest in the production of more natural food components, and so there is an increasing interest to improve the properties of native starches without using chemical modifcations (Ortega‑Ojeda and Eliasson, 2001). Physical modifcation is taken into consideration as it is simple, cheap, and safe and requires no chemicals or biological agents that can be harmful for human use. Tese modifcations treat native starch granules under diferent temperature/moisture combinations, pressure, shear, and irradiation as well as include mechanical attrition to change the physical size of starch granules (Ashogbon and Akintayo, 2014). Physical modifcation is generally classifed into thermal and nonthermal modifcation. Termal modifcation consists of pregelatinization and the hydrothermal processes – annealing (ANN) and heat‑moisture treatment (HMT). In pregelatinization, the granular structure of starch is totally destroyed as a result of heating; there is depolymerization and fragmentation and so the molecular integrity of the starch is not preserved. In disparity, ANN and HMT involve heating starch in water at a temperature below the gelatinization temperature (GT) and above the glass transition temperature (Tg). Consequently, the granular structure of starch is preserved. Nonthermal modifcation includes high‑pressure processing (HPP), micronization, ultrasonication, pulse electric feld (PEF), etc. 7.2.1 Termal Physical Modifcation

Pregelatinized starches (PGSs) may be considered or not to be physically modifed starches (BeMiller and Huber,

7.2.1.1 Pregelatinized

Annealing High moisture treatment

Pre-gelatanized

Figure 7.1 Overview of modifcations.

Hydro-thermal

Thermal

Physical

High pressure processing Micronization Ultrasonication

Non-thermal

Cross-linking

Acid hydrolysis

Octenyl succinic anhydride

Oxidation

Acetylation

Chemical

Modifications Enzymatic

S TA R C H M O D IFI C ATI O NS

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Description of Physical and Chemical Modifcations

MODIFICATION Physical modifcation Thermal physical modifcation Pregelatinized

Hydrothermal Annealing

Heat moisture treatment

Nonthermal physical modifcation High-pressure processing Micronization

High-pressure processing Ultrasonication

REFERENCES

Pregelatinization may be brought about by drum drying, spray drying, and extrusion cooking. Basically PFS is cooked starch which is prepared by complete gelatinization and drying of native starches. Pregelatinization may be brought about by drum drying, spray drying, and extrusion cooking.

Majzoobi et al. (2011); Mounsey and O’Riordan (2008)

Annealing is a process in which a material is held at a temperature lower than its melting temperature, which permits modest molecular reorganization to occur and a more organized structure of lower free energy to form. HMT is one of the hydrothermal modifcation methods at low moisture contents and exposure at a temperature above the glass transition temperature but below the onset temperature of gelatinization for a certain period of time.

Blanshard (1987)

HPP is a nonthermal emerging technology that subjects a product to high pressures (up to 1000 MPa) for a controlled time and temperature. Gamma irradiation of starch, being a physical process, has recently gained increasing interest among researchers as a safer, faster, and more environmentally friendly starch modifcation method over conventional chemical modifcation. HPP is a nonthermal emerging technology that subjects a product to high pressures (up to 1000 MPa) for a controlled time and temperature. Ultrasonication is a green technology and is dependent on the duration of ultrasonication, type and structure of starch, frequency, intensity, water, and temperature of the starch–water system and used to increase the water solubility and decrease the gelatinization/ pasting viscosity/swelling parameters/retrogradation.

Jacobs and Delcour (1998)

Leite et al. (2017) Bhat and Karim (2009)

Leite et al. (2017) Zhu (2015)

(Continued )

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Table 7.1 (Continued) Description of Physical and Chemical Modifcations REFERENCES

MODIFICATION Chemical modifcation Acetylation

Oxidation

Octenyl succinic anhydride

Acid hydrolysis

Cross-linking

Succinylation

Starch acetylation is a common chemical modifcation method during which part of the hydroxyl groups of glucose molecule is replaced by the acetyl group resulting in a modifed molecular structure of the starch. These starches are produced by using acetic anhydride and an alkaline catalyst such as sodium hydroxide. Starch oxidation is chemical modifcation in which starch is reacted with an oxidizing agent (i.e. sodium hypochlorite) under specifc reaction time, controlled pH, and temperature. Modifcation of starch with octenyl succinic anhydride (OSA) is permitted at 3% level on the dry weight basis. OSA starches stabilize the oil-water interface of an emulsion. Acid hydrolysis exposes starch to mineral acids such as H2SO4, HCl, HNO3, and H3PO4 at temperatures below the gelatinization temperature. Cross-linking is a chemical modifcation method during which the native starches are chemically modifed using different cross-linking agents like sodium trimetaphosphate (STMP), sodium tripolyphosphate (STPP), epichlorohydrin (ECH), and phosphoryl chloride (POCl3). Succinylation is a method that chemically modifes starch. It is an esterifcation reaction of a hydroxyl group in the starch molecule with succinic anhydride.

Bello-Perez et al. (2010)

El Halal et al. (2015)

CFR (2001) Murphy (2000)

Dundar et al. (2013) BeMiller (2011)

Lawal (2012)

2015). Basically, PGSs are cooked starches which are prepared by complete gelatinization and drying of native starches. Pregelatinization may be brought about by drum drying, spray drying, and extrusion cooking. Of these, drum drying is the most widely used technique at the industrial scale for pregelatinization of starches (Majzoobi et al., 2011; Mounsey and Riordan, 2008). Destruction of the granular structure, complete fragmentation, and absence of optical birefringence are the characteristics of pregelatinization (Ashogbon and Akintayo, 2014). Tese starches are cooked and dried under those conditions which allow little or no molecular reassociation. Because

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Table 7.2 Findings of Modifcations MODIFICATION Physical Pregelatinized

Annealing Heat moisture treatment

High-pressure processing Micronization

Chemical Acetylation

Oxidation

Octenyl succinic anhydride Acid hydrolysis

Cross-linking

RESULTS Pre-gelatinized starches hydrate rapidly and are cold water soluble due to which they can be used without cooking. Annealing increased the gelatinization transition temperatures and decreased the GTR in all starches. HMT is reported to cause changes in both the crystalline and amorphous regions to different extents and decreases starch solubility, swelling power, amylose leaching, and peak viscosity but increases the pasting temperature. It provides the possibility to produce foods with high nutritional and sensory qualities and a novel texture. Micronized starch is commonly used as an additive, a modifying agent and a fat substitute in food industries because of its unique surface area and reaction activity. Acetylation reduces relative crystallinity, enthalpy, swelling power, pasting temperature, and viscosity of barley starches and is more stable to heating and shearing than native starch. This modifcation increases the clarity and stability of the gels and reduces the retrogradation. Oxidation reduces relative crystallinity, enthalpy, swelling power, pasting temperature, and viscosity of barley starches and causes an increase in solubility when compared to native starch. Oxidation of barley starch improves paste clarity and adhesiveness making it suitable for use as batters and breadings for coating purposes and in confectionary. OSA starches have hydrophobic and hydrophilic nature, so applicated as fat replacement component in bakery goods and in emulsion and encapsulation applications. Acid hydrolysis can increase the amount of short linear chains such as amylose to favour retrogradation as a mechanism of resistant starch formation. Cross-linked barley starch showed resistance against swelling, higher temperature tolerance, and high viscosity, which makes it suitable for use in soups, gravies, sauces, etc.

REFERENCES BeMiller (2018)

Waduge et al. (2006) Hoover and Manuel (1996); Chung et al. (2009); Pinto et al. (2012) Michel and Autio (2000) Ren et al. (2010)

El Halal et al. (2015) Garcia et al. (2012)

El Halal et al. (2015) Mehfooz et al. (2019)

Balic et al. (2017)

Dundar et al. (2013) Mehfooz et al. (2019)

(Continued )

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Table 7.2 (Continued) Findings of Modifcations MODIFICATION

RESULTS

Succinylation

Succinylation favoured lower gelatinization temperature and retrogradation and lower tendency to form gels. This type of starch is suitable for use in refrigerated and frozen products. It results in higher viscosity, greater thickening power, and a lower retrogradation rate of starch. Chemical substitution of side chains with succinate group results in the inhibition of ordered structure of starch paste, thus retarding retrogradation and resulting in more fuid paste with improved clarity. Succinylated barley starch shows higher swelling power, solubility, water retention, viscosity, and lower tendency to form gels. As compared to transition temperatures of native barley starch, succinylation shows reduced To, Tp, and Tc values. Dual-modifed barley starches exhibited delayed retrogradation during storage and higher stability toward thermal degradation making it appropriate for use in canned, refrigerated, and frozen foods, salad dressings, puddings, and gravies. Enzymes have been used traditionally to modify native starches and to create products with altered solubility, viscosity, and/or gelation properties that fnd broad applications in food, paper, textile, and other industries.

Dual modifcations

Enzymatic

REFERENCES Mehfooz et al. (2019) Olayinka et al. (2011) Craig et al. (1989)

Mehfooz et al. (2019)

You and Izydorczyk (2007); Wang and Wang (2001); Virtanen et al. (1993)

they hydrate rapidly and are cold water soluble, they can be used without cooking (BeMiller, 2018). In drum drying, pregelatinization of starches occurs in a one‑ or two‑step process. In the one‑step process, gelatinization and dehydration of the starch paste are done by feeding the slurry of starch onto the drums. For the two‑step process, frst the slurry is cooked in a heat exchanger and then dehydrated by drum drying (Loisel et al., 2004). Spray drying is presently the most commonly utilized microencapsulation method for ingredients (Reineccius, 2006; Shefer and Shefer, 2003), which provides a high degree of solubility, good emulsifying and drying properties, nonhygroscopic character, bland taste, inertness or nonreactivity, and low cost (Murúa‑Pagola et al., 2009).

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Extrusion technology is a high‑temperature short‑time (HTST) process with the advantage of high versatility and the absence of efuents and is used to overcome pollution by using reduced amounts of reagents (Ashogbon and Akintayo, 2014). Koa et al. (2017) investigated the efects of extruder responses and extrudate properties and concluded that the increased frictional heat with the screw speed enhanced the transverse expansion as well as the browning, rate of starch digestion, and rapidly digestible property of the starch extrudates. Hydrothermal treatment is a physical modifcation method that involves the modifcation of physicochemical properties of starch without destroying its granular structure (Olu‑ Owolabi et al. 2011) and takes place when the starch polymers in the amorphous phase are in the mobile rubbery state of the semicrystalline region (Ashogbon and Akintayo, 2014). Annealing and high moisture treatment (HMT) are the two most commonly used hydrothermal treatments used to modify the starches without losing the integrity of the granules. Hydrothermal treatment of starches occurs below the gelatinization temperature of granules, which helps in preserving the granular structure, and the starches remain in the mobile rubbery state during these modifcations (Zia‑ud‑Din, et al., 2017). HMT refers to the treatment of starch at low moisture content (less 35%), whereas during annealing starch is treated in excess or intermediate water (Ashogbon and Akintayo, 2014). 7.2.1.2 Hydrothermal Treatment

It is the physical modifcation of starch granules in which the parameters of moisture, temperature, and heating time determine the results obtained (Tester and Debon, 2000). Te ANN process requires an excess of water (76% w/w) or an intermediate containing water (40% w/w) (Jacobs and Delcour, 1998) and is an efective method used for the reorganization of the molecular chains. Tis process has the advantage of increasing the crystallinity of the materials, weakening structural relaxation (Zia‑ud‑Din et al., 2017) and improving the thermal stability and mechanical properties of the material (Shanshan et al., 2015). Te annealing process is used to approach the glass transition temperature (Tq) in the presence of 7.2.1.2.1 Annealing

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solvents such as water or glycerol, resulting in increased molecular mobility and preventing the initiation of the gelatinization process at the same time (Zia‑ud‑Din et al., 2017). Waduge et al. (2006) performed annealing (50°C for 72 hours, moisture content [m.c.] 75%) on normal, waxy, and high‑amylose hull‑less barley cultivars and concluded that annealing increased the gelatinization transition temperatures and decreased the gelatinization temperature range, had little efect, or decreased the ∆H in barley starches. Further, this modifcation of barley starch changed the B‑ to A‑type polymorph without afecting the crystal size of the granules. 7.2.1.2.2 Heat-Moisture Treatment HMT is a hydrothermal technique which involves agitation of starch granules at low moisture levels but at high temperatures (80–140°C) and low gelatinization temperatures (Hoover, 2010). HMT is reported to bring about changes in both the crystalline and amorphous regions at diferent extents (Hoover and Manuel, 1996) and afects the digestion and pasting properties of starches. HMT decreases starch solubility, swelling power, amylose leaching, and peak viscosity, whereas it increases the pasting temperature of starch (Chung et al., 2009; Pinto et al., 2012). Liu et al. (2019) modifed barley starches with HMT and reported that this hydrothermal modifcation may transform part of the rapidly digestible starch into slowly digestible and/or resistant forms, with reduced paste viscosity and setback viscosity. Interestingly, HMT may change rapidly digestible and resistant starch fractions into slowly digestible forms (Tan et al., 2017). Due to the diversity in the botanical source, moisture content, temperature, heating, cooling, and treatment length, it is very difcult to defne the properties of HMT‑treated starches in a consistent way. Among these conditions, moisture and temperature are the most extensively studied HMT parameters (Ambigaipalan et al., 2014). 7.2.2 Nonthermal Physical Modifcation

When food and food products are subjected to high temperatures for preservation, essential nutrients, vitamins, and favours are lost. To overcome these disadvantages, nonthermal technology is applied to

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food to destroy the pathogenic and spoilage‑causing organisms. As reported by many researchers (Li et al., 2008; Marselles‑Fontanet and Martin‑Bellose, 2007), nonthermal treatments are used to preserve colour, texture, taste, nutrients, and other components of food as compared to the traditional thermal processes. 7.2.2.1 High-Pressure Processing HHP involves the treatment of food material using a pressure of 100–1000 MPa at room temperature to acquire the modifcation and sterilization of the food material. When heating a starch suspension subjected to a pressure higher than 200 MPa, gelatinization takes place at a lower temperature range than when heating at ambient pressure. If the pressure is high enough, gelatinization can occur even at room temperature (Tevelein et al., 1981, Muhr et al., 1982). Tis treatment destroys the noncovalent bonds which resulted in serious structural damages such as protein naturalization and starch gelatinization (Hu et al., 2011). It provides the possibility to produce foods with high nutritional and sensory qualities and a novel texture (Michel and Autio, 2000). Stolt et al. (2000) subjected 10% and 25% barley starch to 400, 450, and 500 MPa pressure for 75 minutes processing and reported that starch gelatinization using high pressure depends on the amount of pressure and the process time. Further, they showed that structural changes at low pressures occurred more slowly, and at 400 MPa pressure, gelatinization was incomplete.

Gamma irradiation of starch, being a physical process, has recently gained increasing interest among researchers as a safer, faster, and more environmentally friendly starch modifcation method over conventional chemical modifcation methods (Bhat and Karim, 2009). Bhatty and Macgregor (1988) studied the infuence of gamma irradiation (10 Mrad) on hull‑less barley and when compared with nonirradiated barley starch they found that irradiated barley starch had completely lost viscoamylogram properties and contained lower‑molecular‑weight amylose and amylopectin. Teir results on scanning and light microscopy revealed no signifcant changes in the external structure of the starch granule. However, internally, the granules were observed to be broken, which was evident during the 7.2.2.2 Micronization

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later stages of gelatinization. Yin and Stark (1988) subjected barley starch to physical damage resulting in the extraction of relatively more amylose. Micronized starch is commonly used as an additive, a modifying agent, and a fat substitute in food industries because of its unique surface area and reaction activity (Ren et al., 2010). Ultrasound treatment is as an efective method of nonthermal physical starch modifcation, with some advantages in terms of quality and higher selectivity, limited application of chemicals, and less processing time. Ultrasound is acoustic energy above the frequency audible to humans, 18–20 kHz, and may be applied on native starch granules suspended in solution or on gelatinized starch (Zuo et al., 2009). It is a green technology and dependent on the duration of ultrasonication, type and structure of starch frequency, intensity, water, and temperature of the starch–water system and is used to increase the water solubility and decrease the gelatinization/pasting viscosity/swelling parameters/retrogradation (Zhu, 2015). As reported by Sujka and Jamroz (2013), this modifcation disrupts the amorphous region of the starch granules, as their shape and size remain unchanged, but their surface becomes porous with an enhancement in swelling power, solubility, and pasting properties. Kaur and Gill (2019) applied two ultrasonication treatment times of 15 and 30 minutes on barley starch and concluded that ultrasonication increased the swelling power, solubility, RDS, and RS content of barley starch. SEM revealed that ultrasonication caused only surface and microstructural changes in the physical geometry of starch granules with minimum efect on their overall integrity. Te rheological properties showed an increase in G′ and G′′ for 15‑minute ultrasonication and decreased with 30‑minute ultrasonication. Tis technique is very important in the following areas of food processing: deforming, extrusion, separation, viscosity alteration, crystallization, extraction, emulsifcation, and homogenization (Iida et al., 2008).

7.2.2.3 Ultrasonication

PEF technology is a nonthermal food preservation method which involves the preservation of food by killing and inactivating the pathogenic microorganisms and enzymes resulting in minimum loss of original taste, colour, nutrients, texture, and

7.2.2.4 Pulse Electric Field

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heat‑liable functional components of the food (Knorr and Angersbach, 1998). PEF technology treats the pumpable liquid material with high‑ intensity electric pulses (over 10 kV cm−1) at short duration (less than 40 μs) in a processing chamber (Zia‑ud‑Din et al., 2017). 7.3 Chemical Modifcations

Starch exhibits thermoplastic properties when disintegrated by the action of heat and shear in the presence of plasticizers. However, the thermoplastic starch has some disadvantages, i.e. poor mechanical strength and high water intensity, which limit its potential applications. To overcome these drawbacks, further chemical modifcation is usually necessary (Wang et al., 2017). Chemical modifcations bring about the structural changes and incorporate new functional groups; these afect the physicochemical properties of the starches and make them ft for various industrial applications. Starch succinate ofers a number of desirable properties such as high viscosity, better thickening power, low gelatinization, and retrogradation (Bhandari and Singhal, 2002). At the present time, modifcation of starch with octenyl succinic anhydride (OSA) is permitted at the 3% level on a dry weight basis for use in food products in many countries (CFR, 2001). Chemical modifcation involves the introduction of functional groups on the starch molecule without afecting the morphology or size distribution of the granules. Chemical modifcations generate signifcant changes in starch behaviour, gelatinization capacity, retrogradation, and paste properties (López et al., 2010). Food and nonfood industries expand starch properties and improve them through chemical modifcations. 7.3.1 Acetylation

Starch acetylation is a common chemical modifcation method during which part of the hydroxyl groups of the glucose molecule is replaced by the acetyl group, resulting in the modifed molecular structure of the starch. Tese starches are produced by using acetic anhydride and an alkaline catalyst such as sodium hydroxide (Bello‑Perez et al., 2010). Acetylation of starch with or above 17% shows a less smooth surface and with 23% catalyst solution, starch granules are partially

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disintegrated (El‑Halal et al., 2015). Sha et al. (2012) reported the same results upon acetylation of rice starch. During acetylation, starch granules are disrupted due to the damage of intermolecular hydrogen bonds. Acetylation reduces relative crystallinity, enthalpy, swelling power, pasting temperature, viscosity, and retrogradation of barley starches while increasing the water solubility (Bello‑Perez et al., 2010; El Halal et al., 2015), and acetylated starches are more stable to heating and shearing than native starch. Acetylated starches perform diferent functions depending on the degree of substitution (DS). Te acetylated barley starches show DS ranging between 0.08 and 0.31 (El‑Halal et al. 2015). Te starches with low DS of about 0.01–0.2 may act as adhesion, thickening, texturizing, flm‑forming, stabilizing, and binding agents. In the food industry, acetylated starch is incorporated in baked goods, sauces, frozen foods, canned pie fllings, baby foods, snack foods, and salad dressings (Zia‑ud‑Din et al., 2017). Nonfood applications of acetylated starches include wrap‑sizing for textiles, biodegradable flms, and surface‑sizing for papers and gummed tape adhesives (El Halal et al., 2015). 7.3.2 Oxidation

Starch oxidation is chemical modifcation in which starch is reacted with an oxidizing agent (i.e. sodium hypochlorite) under a specifc reaction time, controlled pH, and temperature. Generally, during this modifcation, carbonyl and carboxyl groups are introduced into the starch, which alters the physicochemical and structural properties of starches. Te oxidation process with diferent concentrations of active chlorine promotes the formation of carbonyl and carboxyl groups, and the carbonyl content of the barley starch increases as the concentration of active chlorine is increased. Oxidation decreases the ∆H of gelatinization, SP, and viscosity during the pasting event, while increasing the melting temperature of retrograded starch. Oxidation degrades both amylopectin and amylose as revealed by chromatographic analysis (El Halal et al., 2015). Oxidized starches may be used in batters and bread d as food coating, in confectionary as binders, as dairy texturizers, as well as in the paper, textile, and laundry industries (Vanier et al., 2012).

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7.3.3 Octenyl Succinic Anhydride

Starch succinate ofers a number of desirable properties such as high viscosity, better thickening power, low gelatinization, and retrogradation (Bhandari and Singhal, 2002). At the present time, modifcation of starch with OSA is permitted at the 3% level on a dry weight basis for use in food products in many countries (CFR, 2001). OSA starches stabilize the oil‑water interface of an emulsion. Te glucose part of the starch binds the water and lipophilic, the octenyl part binds oil, and the separation of the oil and water phases is prevented (Murphy, 2000). OSA‑modifed starch has a signifcantly higher viscosity than native starch and as OSA content increases, the paste viscosity increases (Song et al., 2006). Nilsson and Bergenståhl (2006) prepared OSA‑modifed barley starches with diferent degrees of substitution (0.0104–0.0224) and studied the oil–water (O/W) interfaces. As reported by Balic et al. (2017), OSA starches have a hydrophobic and hydrophilic nature and thus are used as a fat replacement component in bakery goods and in emulsion and encapsulation applications. 7.3.4 Acid Hydrolysis

Acid hydrolysis is applied to starches to increase the amount of short linear chains such as amylose to favour retrogradation as a mechanism of resistant starch formation. Acid hydrolysis exposes starch to mineral acids such as H 2SO4, HCl, HNO3, and H3PO4 at temperatures below the gelatinization temperature (Dundar et al., 2013). In acid hydrolysis, the hydroxonium ion attacks the oxygen in the glycosidic bond and later hydrolyzes the linkage. An acid works on the starch granule surface prior to entering the inner region of starch. Acid modifcations can alter the physicochemical properties but keep the granule structure intact (Bentacur et al., 1997). Dundar et al. (2013) exposed waxy, regular, and high‑amylose hull‑less barley to partial acid hydrolysis (1.0 and 2.2 N HCl for 30–240 minutes) and reported that this study would beneft the starch industry, since the amount of the phosphorylating reagent required for increasing thermal stability and/or freeze‑thaw stability may be decreased substantially.

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7.3.5 Cross-Linking

Cross‑linking is a chemical modifcation method during which the native starches are chemically modifed using diferent cross‑linking agents like sodium trimetaphosphate (STMP), sodium tripolyphosphate (STPP), epichlorohydrin (ECH), and phosphoryl chloride (POCl3) (Kim et al., 2010; Sajilata et al., 2006). Tis technique is believed to play an important role in improving the functional properties as well as the freeze‑thaw and the cold storage stabilities of the starch molecule (BeMiller, 2011). Among the cross‑linking agents, POCl3 has the ability to impart greater viscosity than STMP and EPI‑treated granules (Hirsch and Kokini, 2002). As far as cross‑linking is concerned, it does not substitute starch molecules but rather stabilizes and strengthens starch granules. Te strengthening of starch chain linkages through cross‑linking results in the lower probability of the polymer to breakdown under high‑temperature, low‑acidity, and high‑shear processing conditions (Jyothi et al. 2006). Mehfooz et al. (2019) cross‑linked barley with STMP and STPP in the ratio of 99:1 and reported that cross‑linking showed higher values of To, Tp, and Tc as compared to the transition temperatures of native barley starch (Mehfooz et al., 2019). Te morphological characteristics of cross‑linked starches have been studied by scanning electron microscopy (SEM), and the results reported rough surface and some dents of starch granules under ×4000 magnifcation. Cross‑linking altered the pasting profle of the barley starches with peak viscosity and increased pasting temperature, as compared to their native counterparts (Mehfooz et al., 2019). 7.3.6 Succinylation

Te most common starch chemical modifcation in the food industry is done by esterifying native starch with succinic anhydride to produce succinylated starches Succinyl groups are formed by esterifying the available hydroxyl groups on C2, C3, and C6 carbons of the anhydroglucose units in the starch molecules so that theoretically, the highest DS is 3. However, the Food and Drug Administration (FDA) allows an average of 0.05 for succinylated starches, for food and pharmaceutical applications (Calderón‑Castro et al., 2019). Chemical substitution

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of side chains with the succinate group results in the inhibition of the ordered structure of starch paste, thus retarding retrogradation and resulting in more fuid paste with improved clarity (Craig et al.,1989). Succinylated barley starch showed higher swelling power, solubility, water retention, viscosity, and lower tendency to form gels. Tis chemical modifcation reduced the pasting temperature of barley starch, indicating weakening of granules. As compared to the transition temperatures of native barley starch, succinylation showed reduced To, Tp, and Tc values (Mehfooz et al., 2019). Tis could be possibly due to the hydrophilic nature of succinic groups that ease penetration of water. Tis reduces the thermal energy and the transition temperature owing to changes in the crystalline structure required for gelatinization by changing the coupling forces between the amorphous and crystalline regions of starch granules. Indentations and some roughness were also observed for oxidized and succinylated starches. 7.3.7 Dual Modifcation

In order to further improve the functional properties and utilization of starches in various kinds of applications, chemical dual and other types of dual modifcation methods have been introduced in diferent kinds of starches. Dual modifcation of starches involves the combination of either chemical and physical modifcation methods or chemical and enzymatic modifcation methods. But the most commonly used is the dual chemical modifcation method that is widely used to modify the starches, which involves a combination of two chemical modifcation methods such as acetylation/oxidation, cross‑ linking/acetylation, or cross‑linking/hydroxypropylation (Huang et al., 2007; Raina et al., 2006; Lui and Corke, 1999; Adebowale et al., 2006; Zamudio‑Flores et al., 2010). Mehfooz et al. (2019) performed dual modifcation: (a) oxidation + cross‑linking and (b) succinylation + cross‑linking. For cross‑linking, STMP and STPP were added in the same quantity. Reduced swelling power, solubility and water retention ability, and delayed retrogradation were observed in cases of oxidized cross‑linked and succinylated cross‑linked barley starches. Dual‑modifed barley starches showed a clear distortion in the granular structure for oxidized cross‑linked surface roughness, whereas for

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succinylated cross‑linked barley starch signs of depression on their surface were shown (Mehfooz et al., 2019). Succinylated cross‑linked barley starches showed an increment in peak viscosity and pasting temperature as compared to native barley starch and increase in peak viscosity may be due to the attachment of hydrophilic succinyl moieties in the starch chains (Shaikh et al., 2015). 7.4 Enzymatic Modifcations

Various enzymatic modifcations have been applied to increase the RS content (Kim et al., 2013, 2015; Harder et al., 2015; Sorndech et al., 2016), to produce malt (Patindol et al., 2012; Chu et al., 2014), and to study the infuence of starch structure/type on starch degradation (You and Izydorczyk, 2007; Naguleswaran et al., 2013, 2014). Enzymics have been used traditionally to modify native starches and to create products with altered solubility, viscosity, and/or gelation properties that fnd broad applications in food, paper, textile, and other industries (You and Izydorczyk, 2007; Wang and Wang, 2001; Virtanen et al. 1993). Amylases can hydrolyze both the soluble starch polymers as well as the intact starch granules (Planchot et al. 1995). Generally, amylases source, starch botanical source, and the ultrastructural features of granule organization (interchain associations, type and degree of crystallinity, and amylose–lipid interactions) infuence the hydrolysis kinetics (Gerard et al., 2001; Planchot et al. 1995; Lauro et al., 1993). You and Izydorczyk (2007) used α‑amylase (Bacillus licheniformis) for normal, high‑amylose, and zero‑amylose barley starch hydrolysis and reported that the greatest yield of α‑amylase‑treated starches was obtained for the high‑amylose (79.9– 86.6% w/w) followed by normal (61.1–76.1% w/w), and zero‑amylose waxy starch (44.2–64.5% w/w). Te solubilization of granules and degradation of starch polymers during enzymic hydrolysis of barley starches were afected by the amount of amylose in starch granules. As an alternative approach to preparing RS products, a few studies attempted to treat 65 partially and/or completely gelatinized starches with amylosucrase (NpAS) from Neisseria 66 polysaccharea (Kim et al., 2013; Ryu et al., 2010). Tus, NpAS treatment of starch molecules resulted in the extension of α‑glucan chains at their nonreducing ends

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(Kim et al., 2013; Ryu et al., 2010), thus lengthening the starch branch chains and increasing the weight‑average molecular weights and gyration radii of the overall molecules (Shin et al., 2010). Kim et al. (2015) found that, compared with the native starch, NpAS‑treated starches exhibited lower solubility and swelling power, lower pasting viscosity, and a large increase in the melting peak temperature. Consequently, NpAS treatment of pregelatinized starches in this study would be a potential way of replacing commercial RS production. 7.5 Conclusions

Various chemical, enzymatic, and physical modifcations have been applied to alter the structure and physicochemical properties of starch. All the modifcation processes have the tendency to produce starches with altered physicochemical properties and modifed structural attributes for various food and nonfood applications and imparting diferent novel processing characteristics. Te most important application of PGSs starches is in puddings, pie fllings, and baby foods as a thickening agent because of their ability to hydrate instantly and swell in water at ambient temperature. Progress in understanding the high value of chemically modifed starches has encouraged the starch industry to produce modifed starches using diferent modifcation reagents and starch sources. Enzymics have been used traditionally to modify native starches and to create products with altered solubility, viscosity, and/or gelation properties that fnd broad applications in food, paper, textile, and other industries. Terefore, it seems that barley starch has great potential to complement or compete with other commercially important starches in some applications. However, the wide diversity in the starch properties of barley genotypes should be better exploited for various uses.

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Liu, K., Zhang, B., Chen, L., Li, X., and Zheng, B. 2019. Hierarchical structure and physicochemical properties of highland barley starch following heat moisture treatment. Food Chemistry 271:102–108. Loisel, C., Maache‑Rezzong, Z., and Doublier, J. P. 2004. In: Tomasik, P., Yuryev, V. P., and Bertoft, E. (eds.), Starch: Progress in Structural Studies, Modifcations and Applications. Poland: Polish Society of Food Technologist’s, Małopolska Branch. López, O. V., Zaritzky, N. E., and García, M. A. 2010. Physicochemical characterization of chemically modifed corn starches related to rheological behavior, retrogradation and flm forming capacity. Journal of Food Engineering 100(1):160–168. Lui, H., and Corke, H. 1999. Physical properties of cross‑linked and acetylated normal and waxy rice starch. Starch – Stärke 51(7):249–252. Majzoobi, M., Kaveh, Z., Blanchard, C. L., and Farahnaky, A. 2015. Physical properties of pregelatinized and granular cold water swelling maize starches in presence of acetic acid. Food Hydrocolloids 51:375–382. Majzoobi, M., Radi, M., Farahnaky, A., Jamalian, J., Tongdang, T., and Mesbahi, G. 2011. Physicochemical properties of pre‑gelatinized wheat starch produced by a twin drum drier. Journal of Agricultural Science and Technology 13(2):193–202. Marselles‑Fontanet, A. R., and Martin‑Belloso, O. 2007. Optimization and validation of PEF processing conditions to inactivate oxidative enzymes of grape juice. Journal of Food Engineering 83(3):452–462. Mehfooz, T., Ali, T. M., and Hasnain, A. 2019. Efect of cross‑linking on characteristics of succinylated and oxidized barley starch. Journal of Food Measurement and Characterization 13(2):1058–1069. Michel, M., and Autio, K. 2000. High pressure—A tool for food structure engineering. In: M. E. G. Hendrickx, D. Knorr, Ultra High Pressure Treatments of Foods. US: Springer, Aspen Publishers. Mounsey, J. S., and O’Riordan, E. D. 2008. Infuence of pre‑gelatinised maize starch on the rheology, microstructure and processing of imitation cheese. Journal of Food Engineering 84(1):57–64. Muhr, A. H., and Blanshard, J. M. V. 1982. Efect of hydrostatic pressure on starch gelatinisation. Carbohydrate Polymers 2(1):61–74. Murphy, P. 2000. Starch. In: Phillips, G. O., and Williams, P. A. (eds.), Handbook of Hydrocolloids. Boca Raton, FL: CRC Press, 41–65. Murúa‑Pagola, B., Beristain‑Guevara, C. I., and Martínez‑Bustos, F. 2009. Preparation of starch derivatives using reactive extrusion and evaluation of modifed starches as shell materials for encapsulation of favoring agents by spray drying. Journal of Food Engineering 91(3):380–386. Naguleswaran, S., Vasanthan, T., Hoover, R., and Bressler, D. 2013. Te susceptibility of large and small granules of waxy, normal and high‑amylose genotypes of barley and corn starches toward amylolysis at sub‑gelatinization temperatures. Food Research International 51(2):771–782.

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Naguleswaran, S., Vasanthan, T., Hoover, R., and Bressler, D. 2014. Amylolysis of amylopectin and amylose isolated from wheat, triticale, corn and barley starches. Food Hydrocolloids 35:686–693. Nilsson, L., and Bergenståhl, B. 2006. Adsorption of hydrophobically modifed starch at oil/water interfaces during emulsifcation. Langmuir 22(21):8770–8776. Olayinka, O. O., Olu‑Owolabi, B. I., and Adebowale, K. O. 2011. Efect of succinylation on the physicochemical, rheological, thermal and retrogradation properties of red and white sorghum starches. Food Hydrocolloids 25(3):515–520. Olu‑Owolabi, B. I., Afolabi, T. A., and Adebowale, K. O. 2011. Pasting, thermal, hydration, and functional properties of annealed and heat‑moisture treated starch of sword bean (Canavalia gladiata). International Journal of Food Properties 14(1):157–174.Ortega‐Ojeda, F. E. and Eliasson, A. C. 2001. Gelatinisation and retrogradation behaviour of some starch mixtures. Starch‐Stärke 53(10):520–529. Patindol, J., Mendez‑Montealvo, G., and Wang, Y. J. 2012. Starch properties of malted barley in relation to real degree of fermentation. Starch – Stärke 64(7):517–523. Pinto, V. Z., Vanier, N. L., Klein, B., Zavareze, E. D. R., Elias, M. C., Gutkoski, L. C., et al. 2012. Physicochemical, crystallinity, pasting and thermal properties of heat–moisture‑treated pinhao starch. Starch – Stärke 64(11):855–863. Planchot, V., Colonna, P., Gallant, D. J., and Bouchet, B. 1995. Extensive degradation of native starch granules by alpha‑amylase from Aspergillus fumigatus. Journal of Cereal Science 21(2):163–171. Raina, C. S., Singh, S., Bawa, A. S., and Saxena, D. C. 2006. Some characteristics of acetylated, cross‑linked and dual modifed Indian rice starches. European Food Research and Technology 223(4):561–570. Reineccius, G. 2006. Flavor technology. In: G. Reineccius, Flavor Chemistry and Technology. Boca Raton, FL: CRC Press. Ren, G. Y., Li, D., Wang, L. J., Özkan, N., and Mao, Z. H. 2010. Morphological properties and thermoanalysis of micronized cassava starch. Carbohydrate Polymers 79(1):101–105. Ryu, J. H., Lee, B. H., Seo, D. H., Baik, M. Y., Park, C. S., Wang, R., and Yoo, S. H. 2010. Production and characterization of digestion‑resistant starch by the reaction of Neisseria polysaccharea amylosucrase. Starch – Starke 62(5):221–228. Sajilata, M. G., Singhal, R. S., and Kulkarni, P. R. 2006. Resistant starch–A review. Comprehensive Reviews in Food Science and Food Safety 5(1):1–17. Sha, X. S., Xiang, Z. J., Bin, L., Jing, L., Bin, Z., Jiao, Y. J., and Kun, S. R. 2012. Preparation and physical characteristics of resistant starch (type 4) in acetylated indica rice. Food Chemistry 134(1):149–154. Shaikh, M., Ali, T. M., and Hasnain, A. 2015. Post succinylation efects on morphological, functional and textural characteristics of acid‑thinned pearl millet starches. Journal of Cereal Science 63:57–63.

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Shanshan, L., Jiyou, G., Jun, C., Haiyan, T., and Yanhua, Z. 2015. Efect of annealing on the thermal properties of poly (lactic acid)/starch blends. International Journal of Biological Macromolecules 74:297–303. Shefer, A., and Shefer, S. 2003. Novel encapsulation system provides controlled release of ingredients. Food Technology 57:40–42. Shin, H. J., Choi, S. J., Park, C. S., and Moon, T. W. 2010. Preparation of starches with low glycaemic response using amylosucrase and their physicochemical properties. Carbohydrate Polymers 82(2):489–497. Singh, J., Kaur, L., and McCarthy, O. J. 2007. Factors infuencing the physico‑chemical, morphological, thermal and rheological properties of some chemically modifed starches for food applications – A review. Food Hydrocolloids 21(1):1–22. Song, X. Y., He, G. Q., Ruan, H., and Chen, Q. H. 2006. Preparation and properties of octenyl succinic anhydride modifed early indica rice starch. Starch – Stärke 58(2):109–117. Sorndech, W., Sagnelli, D., Meier, S., Jansson, A. M., Lee, B. H., Hamaker, B. R., and Blennow, A. 2016. Structure of branching enzyme‑ and amylomaltase modifed starch produced from well‑defned amylose to amylopectin substrates. Carbohydrate Polymers 152:51–61. Stolt, M., Oinonen, S., and Autio, K. 2000. Efect of high pressure on the physical properties of barley starch. Innovative Food Science and Emerging Technologies 1(3):167–175. Sujka, M., and Jamroz, J. 2013. Ultrasound‑treated starch: SEM and TEM imaging, and functional behaviour. Food Hydrocolloids 31(2):413–419. Sweedman, M. C., Tizzotti, M. J., Schäfer, C., and Gilbert, R. G. 2013. Structure and physicochemical properties of octenyl succinic anhydride modifed starches: A review. Carbohydrate Polymers 92(1):905–920. Tan, X. Y., Li, X. X., Chen, L., Xie, F. W., Li, L., and Huang, J. D. 2017. Efect of heat‑moisture treatment on multi‑scale structures and physicochemical properties of breadfruit starch. Carbohydrate Polymers 161:286–294. Tester, R. F., and Debon, S. J. J. 2000. Annealing of starch – A review. International Journal of Biological Macromolecules 27(1):1–12. Tevelein, J. M., Van Assche, J. A., Heremans, K., and Gerlsma, S. Y. Ž. 1981. Gelatinisation temperature of starch, as infuenced by high pressure. Carbohydrate Research 93(2):304307. Vanier, N. L., Zavareze, E. R., Pinto, V. Z., Klein, B., Botelho, F. T., Dias, A. R. G., and Elias, M. C. 2012. Physicochemical, crystallinity, pasting and morphological properties of bean starch oxidised by diferent concentrations of sodium hypochlorite. Food Chemistry 131(4):1255–1262. Virtanen, T., Autio, K., Suortti, T., and Poutanen, K. 1993. Heat‑induced changes in native and acid‑modifed oat starch pastes. Journal of Cereal Science 17(2):137–145. Waduge, R. N., Hoover, R., Vasanthan, T., Gao, J., and Li, J. 2006. Efect of annealing on the structure and physicochemical properties of barley starches of varying amylose content. Food Research International 39(1):59–77.

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Wang, D. W., Kuo, M. C., Yang, L., Huang, C. Y., Wei, W., Huang, C. M., and Yeh, J. T. 2017. Strength retention and moisture resistant properties of citric acid modifed thermoplastic starch resins. Journal of Polymer Research 24(12):234. Wang, L., and Wang, Y. J. 2001. Structures and physicochemical properties of acid‑thinned corn, potato, and rice starches. Starch – Stärke 53(11):570–576. Yin, X. S., and Stark, J. R. 1988. Molecular modifcation of barley starch granules by diferent types of physical treatment. Journal of Cereal Science 8(1):17–28. You, S., and Izydorczyk, M. S. 2007. Comparison of the physicochemical properties of barley starches after partial α‑amylolysis and acid/alcohol hydrolysis. Carbohydrate Polymers 69(3):489–502. Zamudio‑Flores, P. B., Torres, A. V., Salgado‑Delgado, R., and Bello‑Perez, L. A. 2010. Infuence of the oxidation and acetylation of banana starch on the mechanical and water barrier properties of modifed starch and modifed starch/chitosan blend flms. Journal of Applied Polymer Science 115(2):991–998. Zhu, F. 2015. Impact of ultrasound on structure, physicochemical properties, modifcations, and applications of starch. Trends in Food Science and Technology 43(1):1–17. Zia‑ud‑Din, Xiong, H., and Fei, P. 2017. Physical and chemical modifcation of starches: A review. Critical Reviews in Food Science and Nutrition 57(12):2691–2705. Zuo, J. Y., Knoerzer, K., Mawson, R., Kentish, S., and Ashokkumar, M. 2009. Te pasting properties of sonicated waxy rice starch suspensions. Ultrasonics Sonochemistry 16(4):462–468.

8 M ALT

AND

M ALT P RODUCTS

8.1 Introduction

Barley is a primary cereal processed into malt and mainly used for brewing and distilling, in which the malting quality is an important factor in determining the quality of the manufactured products (Kochevenko et al., 2018). About 30% of the barley produced globally is used for malting, and thus breeding barley varieties with high‑quality malt for processing is an important goal (Bond et al., 2015; Walker and Panozzo, 2016; Kochevenko et al., 2018). Two types of barley are frequently used for the malting process: six‑row barley and two‑ row barley. Two‑row barley produces malt with a large extract, lighter colour, and less enzyme content than the six‑row type (Broderick et al., 1977). 8.2 Malting Process

Malting is a controlled germination process of cereals to ensure a specifc physical and biochemical change within the grain, which is then stabilized by grain drying. It involves three steps – steeping, germination, and kilning. 8.2.1 Steeping/Soaking

During steeping, the grain imbibes water till the moisture content reaches 42–45% and hydrates the embryo and endosperm to start the metabolic process of germination. It generates grain softening and increases water availability (Baranwal, 2017). Cleaned and sized barley is placed in cylindrical steep tanks equipped with conical bottoms; each steep tank has water and inlet and outlet pipes, and compressed air is fed from the tank bottom for vigorous aeration and mixing 14 9

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of barley at 50–60°F. When the moisture content of 43–45% (for uniform germination) in the barley is reached, steeping is stopped. During steeping as the moisture level of barley increases, respiration in the barley also increases, requiring frequent water changes and vigorous aeration to maintain a good, uniform germination rate. 8.2.2 Germination

Te germination process results in structural modifcation and synthesis of new compounds and improves the nutritional value and stability of grains (Ha et al., 2016). Tis phase begins after the kernels have absorbed enough water to start enzyme production and starch hydrolysis. Conditions that are necessary during the germination phase are moisture content, temperature, length of the germination time, and oxygen availability. Germination takes about 2–6 days and occurs rapidly between 20°C and 30°C with an optimum temperature of 25–28°C. Te most important physiological processes associated with the germination phase are the synthesis of amylases, proteases, and other endogenous hydrolytic enzymes (Baranwal, 2017). Te steeped barley is transferred to the germinating foors or rooms and 45% kernel moisture, 60–70°F temperature, and adequate supply of O2 must be maintained. Te low temperature helps to reduce the loss of dry material through respiration. Depending on the barley type and requirements of the individual malt house, three basic variations are used in the germination process. First, the temperature is allowed to rise during the early germination stages due to the heat of respiration and is then cooled, and the temperature is kept low until the desired germination level is reached. Tis process results in well‑modifed malts and also reduces malting losses, particularly with vigorously germinated barleys. For the second stage of germination the lower temperature range is maintained for the frst few days, then it is raised during the latter germination stages. Tis method is good for slow‑growing barley and minimizes the danger of overgermination. In the third process, a regular increase and decrease in temperature throughout the germination period is used. Te changes are gradual and kept in the optimum 60–70°F range. All aspects of germination (moisture content, temperature, aeration, and type of barley) must be kept in constant balance to ensure proper kernel modifcation and economical yield. Te chemical

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changes in the kernel are basically brought about by enzymatic activity, using the energy supplied by the kernel with a resulting loss of dry material. Te total dry material lost in malting is about 8–10%. During seed germination, gibberellic acid (GA) is released by the embryo, which induces a large number of hydrolases in the aleurone layer and begins to degrade the endosperm cell wall (Kok et al., 2019; Bamforth, 2017; Zentella et al., 2002). Ten, many hydrolases enter into the endosperm cells and start to degrade proteins, starches, and lipids. Tese are then transported into the germ where they are further metabolized by the growing seedling (Leder, 2004). In the process, the conversion of nutrients continues, and low‑molecular‑weight sugars, amino acids, fatty acids, and enzymes are formed, which provide substances for subsequent fermentation. Among them, the amount and quality of the converted substances determine the malting quality (Autio et al., 2001; Georg‑Kraemer et al., 2001; Bamforth, 2009). Enzymes, i.e. α‑amylase, β‑amylase, limitdextrinases, β‑glucanase, xylanase, endo‑ and exo‑proteinases, and lipases (Bamforth, 2009; Sammartino, 2015), are activated during germination. α‑ and β‑Amylases and limit dextrinases are involved in the breakdown of starch into fermentable sugars and together contribute to the diastatic power of barley malt. Te amylases and carbohydrase work together to split the barley starch into fermentable sugars, although only about 10% of starch is converted, and the rest is carried through the malting process and is modifed later. Optimum germination produces balanced enzyme production combined with favourable action of such enzymes to modify the starch systems. As a result of the malting process, there is an increase in the enzyme activity, soluble protein, and breakdown of starch into simple sugars, along with the development of the typical colour and favour (Hoseney, 1994). 8.3 Drying

Drying is the fnal stage of the malting process and is required for stopping further growth of the kernels, reducing the moisture content and water activity, hence producing a shelf‑stable product with active enzymes. Drying stops the germination at the peak of enzyme development and starch modifcation. Te heat catalyzes additional reactions, notably favour and colour development.

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Te germination malt is also known as green malt and is fed to the kiln and dried rapidly with high air fow and temperature of 110– 130°F. Te usual practice is to dry to about 6–12% of moisture. Tis is followed by a second drying stage using low temperature for maximum enzyme recovery or higher temperatures for favour development at the expense of enzyme content. In the second stage, reactions take place between the simple sugars, amino acids, and peptides to develop the characteristic colour, favour, and aroma of malt. A temperature of 120–130°F is generally used when making malts in which the presence of enzymes is desired. Selective use of drying times, temperatures, and methods is necessary to achieve a well‑balanced malt having optimum favour, colour, and enzyme activity. When drying has been completed, the sprouts and other extraneous materials are removed, and the kernels are then ready for further processing. Other drying techniques crush the green malt before drying to speed up this phase of the process. Te fnished product has the enzymatic activities of 20o and 60° Lintner levels. Te dry malted grain thus produced can then be coarsely ground, water extracted, and concentrated to reach the fnal basic product “liquid malt extract”; many variations of malt extracts are possible in terms of favour, colour, solids, enzymatic activity, etc., and there are also a variety of syrups available made by mashing. 8.4 Malt Extracts and Syrups

Malt designed for the baking industry is available in many types and varieties, allowing a wide choice of diferent malt products. Wet liquid or dry extracts or syrups, diastatic or nondiastatic, dark brown to light brown colours, are the major characteristics that are considered when choosing the best type of malt for use in a given bakery product. 8.4.1 Extracts

Contain only barley, and liquid extracts are available at various levels of natural diastatic activity (0–200° Lintner), whereas dry extracts are found in nondiastatic forms.

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8.4.2 Syrups

Syrups are made up of barley and other cereals, usually corn, which is added during the mash stage in the form of corn grits. Te corn grits serve as an added fermentable carbohydrate which the barley enzymes modify along with the barley starch. Te fnished syrups generally are sweeter and have a smoother favour. Syrups less expensive than the extracts with similar favour and colours are also available. Liquid syrups are available in various levels of diastatic activity (0–60° Lintner), with various ratios of barley to corn, and various degrees of brown colour. In these products, the enzymes can come from the natural malting process or from added fungal amylase. Dry syrups are available in various ratios of barley to corn and in diferent shades of brown colour and are available only as the nondiastatic type. 8.4.3 Dry diastatic malts

Dry diastatic malt products are made by blending malted barley, wheat four, and dextrose in ratios designed to produce a fnished product with enzymatic activity of 20° and 60° Lintner levels. 8.4.4 Special malts

Special malts, made by heating until the starch has been gelatinized and partially dextrinized without excessive colour and favour development, are used in various baked foods. Examples include dextrin salt, caramel malt, or black malt. Malt extracts are high in calcium, iron, thiamine, niacin, and ascorbic acid. Malt extract is a fairly nutritionally valuable food product with its minerals and low‑molecular‑weight nitrogenous compounds especially useful as yeast nutrients. 8.5 Malt Types 8.5.1 Pale Lager Malt

Pale lager malts are the most common and major ingredient in light lager beers. Light lager beers require a malt with maximum extract

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and good enzyme potential but with limited development of colour and favour. Pale lager malts are generally made from two‑rowed barley with a protein content of 10.5% (Edney and Izydorczyk, 2003). 8.5.2 Pale Ale Malt

Pale ale malts are used to produce top‑fermented ales. Tey possess darker colours and stronger favours than lager malts, which is achieved by using modifed malt and higher fnal kilning temperatures (90°C). Te higher temperatures favour the favour and colour but reduce the enzymes resulting in more unfermentable dextrins and thus greater body in the fnal beer (Edney and Izydorczyk, 2003). 8.5.3 Vienna Malt

Vienna malt forms the basis for the famous Märzen and Oktoberfest beers, whose characteristics are a golden colour and full malt favour. Te malt is produced by completing the kilning of a typical pale lager malt at a raised temperature (90°C) (Edney and Izydorczyk, 2003). 8.5.4 Munich Malt

Munich malt is characterized by a rich aroma and dark colour and is used to make the dark, aromatic, full‑bodied lager beers of Bavaria. Tis malt is produced from two‑rowed barley with 11.8% protein (Edney and Izydorczyk, 2003). 8.4.5 Caramel Malt

Tese malts are fully modifed green malts, roasted at 65–70°C in a roaster before the drying process, resulting in degradation of starches into sugars at the early stage of kilning. After roasting, these malts are dried at a higher temperature (150–180°C) for developing characteristics of colours and favours. Tese malts give a sweet, caramel‑favoured and golden‑coloured beer with increased fullness and good foam retention. Tey possess no enzymatic activity (Edney and Izydorczyk, 2003).

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8.5.6 Brown and Amber Malts

Tese dark‑coloured malts have little or no enzyme activity and made by roasting low‑moisture green malts. Tey are partially dried (to prevent starch degradation at low temperatures) with good air fows before roasting at temperatures of 130°C. Amber malts begin with a pale ale‑type malt that has been previously kilned. Te kilned malt is roasted at temperatures of 100–150°C, depending on the colour desired (Edney and Izydorczyk, 2003). 8.5.7 Chocolate and Black Malts

Tey are customarily used in stouts where they bring a favour described as dry, burnt, and astringent but with the hint of a rich, sweet taste. Te malts start with an undermodifed malt that has been kilned at low temperatures to a moisture of 4–6%. Te dried malt is transferred to a roaster where temperatures are raised to 215°C or 220°C for chocolate and black malts, respectively. Te major diference between the two malts is the length of roasting with the darker‑coloured black malts requiring longer times (Edney and Izydorczyk, 2003). 8.6 Food Applications 8.6.1 Bakery Goods

Diastatic malt, either liquid or dry, supplements the amylase in the wheat four to provide sugar for fermentation, to improve pan fow, and to improve crumb colour, and break and shed in bread‑type products. In crackers, diastatic malts improve fermentation, and the dough conditioning improves sheeting and laminating and also improves crust colour and favour. Nondiastatic malt contributes to crust colour and favour in crackers and cookies. In nonfermented bakery foods, nondiastatic malts are used, and they contribute all the qualities to the fnished product except those related to enzymatic activity. In soda crackers, 1% diastatic malts help to maintain the sugar balance lost during the long sponge period. Crackers with addition of 0.5% of 20° Lintner malt syrup are used to correct the tough, finty, or cupped crackers. Improved pan fow, gas retention, and better volume

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in buns and rolls may be achieved by the addition of malt. For preparing pizza doughs, English mufns, Kaiser rolls, and bread sticks, diastatic and nondiastatic malts are used for favour, colour, easier dough making, faster proof, and better baking and crust characteristics. All dark variety breads, rye, sour rye, and whole wheat require darker malts for better processing and enhanced characteristics of the fnished product. 8.6.2 Malted Milk Powder

It is a complex blend of malted barley, wheat extract, milk, salt, and baking soda. It is widely used in confectionary to make candy centres, in dairy desserts to favour ice cream, and in milkshakes. It contains approximately 10–25% milk solids and may be used in baked goods to provide sweetness, favour, and milk solids. Malted milk powder provides a sweet, pleasing favour to sweet goods and works well in icings and fllings (Hansen and Wasdovitch, 2005). 8.6.3 Beer

Beer is one of the most widespread and largely consumed alcoholic drinks in the world. Te main constituents of beer are water (92%), ethanol (4%), carbohydrates (2.8%), proteins (0.5%), and carbon dioxide (0.5%) (Verhagen, 1994). Beer is produced in two steps – malting and brewing. Te malting process consists of three steps: steeping, germination, and kilning. Brewing is a complex fermentation process comprising of several steps with the objective to produce wort and converting the wort into beer through fermentation by adding yeast and subsequent maturation of the end product (Harrison, 2009; Pires and Brányik, 2015). Te steps involved in the brewing process are milling, mashing, hop addition, and kettle boiling (Figure 8.1). Te composition of typical beer is shown in Table 8.1. During milling, the malt is subjected either to dry or wet milling. Barley malt is milled using a roller mill, which provides coarse grist and husks that remain intact, and the hammer mill provides comparatively fner grist and breaks up the outer husk. Wort

8.6.3.1 Milling

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Barley Cleaning and grading Steeping in water (temperature 15-20 oC, moisture content 15 to 45%) Germination (3-6 days, 15-20 oC) Kilning Malt Milling Mashing Filtration Wort

Hops

Fermentation Maturation Carbonation and bottling

Figure 8.1

Production of beer.

obtained from roller‑milled malt powder is usually fltered by lautering because of the presence of intact husk, whereas wort from hammer‑ milled malt powder is fltered using mash flters (Kok et al., 2019). Some adjuncts are added to malt to give its characteristic favours and the desired properties to the products. Brewing adjuncts are prepared from unmalted cereals, mainly corn and rice, and are relatively pure carbohydrates without a signifcant amount of lipid, enzymes, or proteins. Grits and fakes adjuncts are added during mashing, and syrups are added during kettle boiling. Grits and fakes are prepared by milling decorticated and degermed corn or rice. Syrups are prepared from corn starch by acid hydrolysis. Te use of micronized and extruded cereals as adjuncts has been studied, but the current application is

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Table 8.1

Composition of Beer

PARAMETERS Specifc gravity Alcohol by wt. Alcohol by vol. Reducing sugars pH Nitrogen Oxygen Oxygen/air CO2 by wt. Acidity Dextrins Iron Tannins Ash Diacetyl FRACTIONAL CARBOHYDRATES Glucose Fructose Sucrose Maltose Maltotriose Higher saccharides Total saccharides Total protein Calories

VALUES 1.0121 3.63% 4.60% 1.160 4.35 1.01 cm3 0.19 cm3 15.80% 0.460% 0.135 2.73% 0.175 ppm 55.40 ppm 0.148% 0.210 ppm 0.001% Trace Trace 0.10% 0.20% 3.04% 3.83% 0.299% 168.30 kcal/400 ml

Source: Ohlmeyer and Matz (1970)

limited due to poor wort and beer fltration performance (Briggs et al., 1986; Delcour et al., 1989). Brewing from raw grains needs to be pretreated by cooking to pregelatinize their starches, which can be achieved by simple faking (Lewis and Young, 2001) or micronization and extrusion (Iserentant, 2003; Kokić et al., 2013). Te main objective of mashing is to extract the starch and proteins/peptides from grains and subject them to fermentation through enzymatic hydrolysis to sugars and small peptides/amino acids (Stewart, 2013) and involves the manipulation of

8.6.3.2 Mashing

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the temperature profle and appropriate duration to provide optimal enzyme catalysis conditions for the extraction. Te gelatinization temperature of starch and accessibility of enzymes to that temperature are considered during the mashing process, and starch gelatinization (disruption of the multiscale structure of the starch granules) (Wang et al., 2016) of barley malt is completed at the saccharifcation rest temperature. Raw and malted barley both have similar low‑starch gelatinization temperatures and may be milled and added directly to barley malt grist (Kok et al., 2019). During mashing, malt powder is mixed with water at a temperature of 38–50°C. To this mash, cooked starch adjuncts are added, which are at about 100°C. Tis results in increasing the temperature of malt around 75°C. At this temperature, saccharifcation is favoured and starches are converted into simple sugars. After that, the temperature is increased to 80°C for inactivation of enzymes. At the end of this operation, all the insoluble materials settle at the bottom of the container. Te mashing tub serves as a flter so that liquid which is obtained is clear and known as wort, containing 12–14% sugars. Te major fermentable sugars from the hydrolysis of starch in a typical malt wort are glucose (10–15%), maltose (50–60%), and maltotriose (15–20%) (Stewart, 2013). Te presence of β‑glucans increases the viscosity of wort and decreases its flterability (Bamforth and Martin, 1981; Scott, 1972). Barley malt has a lower β‑glucan content compared to raw barley due to degradation by endo‑β‑glucanase, an enzyme whose expression level increases signifcantly during malting (Bamforth and Martin, 1981). Te pistillate fowers of the hop plant Humulus lupulus, which are cone‑like in appearance are used and is commonly referred to as hops. Hops contain essential oils (1%) and resins (15%). Te essential oils are a mixture of numerous compounds, and most of them are hydrocarbons, and the monoterpene myrcene (Coghe et al., 2006) the sesquiterpenes caryophyllene (Guido et al., 2007), and humulene (Sovrano et al., 2006) are the most dominant hydrocarbons, while others are oxygenated esters, alcohols, and carbonyl compounds and provide the characteristic aroma. Resins are classifed as soft and hard resins and are responsible for the pleasant

8.6.3.3 Addition of hops

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bitterness that hops impart to beer. Te soft resin fraction contains two related series of compounds, called α‑acids and β‑acids. Te hard resin fraction consists of a mainly undefned mixture of oxidation products of the soft resins (Verhagen, 1994). Main components of α‑acids are cohumulone (Wackerbauer et al., 2003), humulone (Arts et al., 2007), and adhumulone (Hirota et al., 2006), while pre‑ and posthumulone are only present as minor components. Typically, aroma hops are relatively low in α‑acids (3–6%) while bitter hops have a high content of α‑acids (up to 18%) (Verhagen, 1994). β‑acids consist of fve diferent homologues: colupulone (Guido et al., 2005), lupulone (Kühbeck et al., 2006a), adlupulone (Kühbeck et al., 2006b), and minor quantities of prelupulone and postlupulone. For the brewers, the acids are of prime importance because they are the precursors of the bitter compounds in beer, the so‑called iso‑acids. Tey are formed during the boiling of wort with hop where the hop α‑acids thermally isomerize into the intense bitter‑tasting iso‑acids. Te iso‑acids also stabilize beer foam (Bamforth, 1985, 2004) and are antibacterial agents (Simpson and Smith, 1992; Blanco et al., 2007). Te wort after addition of hops is pumped into a brew kettle where boiling occurs. Tis operation is carried out for 2.5 hours. Te purpose of boiling is to concentrate the wort, to sterilize, inactivate the enzymes, coagulate and precipitate proteins, caramelize sugar, and to provide resins (humulone and cohumulone) which are active against gram +ve bacteria. 8.6.3.4 Fermentation/pitching For bottom‑fermented/lager‑beer Sacch-

aromyces uvarun and for top‑fermented/ale Saccharomyces cerevisiae is generally used for inoculation of cooled sweet wort. Typically, lager‑beer strains are bottom fermented at temperatures of 5–8°C, while ale beers are top fermented at 10–25°C (Verhagen, 1994). Te fermentation is completed in 8–14 days during which yeast converts the sugar of wort into alcohol, a small amount of glycerol, and acetic acid, and also some higher alcohols due to protein and fat derivatives. At the end of the fermentation, a high amount of CO2 is produced, the amount of foam is increased, and the yeast settles down at the bottom (for bottom fermented), and this indicates the end of the fermentation.

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Te green or young beer is stored in vats at 0°C for several weeks to several months. During aging, precipitation of proteins, yeast, resin, and other undesirable substances takes place, and the beer becomes clear and mature. At the end of aging, several ester compounds are formed, which increase the favour and taste, and the beer body changes from harsh to smooth.

8.6.3.5 Maturation

After maturation, the beer is carbonated to CO2, and this is done with the CO2 collected during fermentation. Beer is then cooled, clarifed (bentonite), or fltered (cellulose acetate) and packed in bottles/cans/barrels. 8.6.3.6 Finishing, carbonation and bottling

8.6.4 Malt Vinegar

Malt vinegar is produced without intermediate distillation from the two‑stage fermentation of malted barley with or without the addition of other cereals. First, yeast converts sugar into ethanol anaerobically and then ethanol is oxidized to acetic acid aerobically. It involves three steps: mashing, fermentation, and acetifcation. After the mashing and fermentation process, the alcoholic liquid is inoculated with Acetobacter cultures. Malt vinegar is straw‑coloured and contains 4% w/v of acetic acid. Distilled malt vinegar is prepared by distilling malt vinegar. Tis product contains only the volatile constituents of the original vinegar and is colourless; it is generally used for the preparation of pickled silver skin onions (Plessi and Papotti, 2003). 8.7 Conclusions

Te demand for natural and health‑promoting food and food products made with cereal grains continues to grow. Barley malt, or “malt” as it is commonly known, is used in production as brewing malt, and additionally in distilling, vinegar production, and commercially as a food ingredient to enhance colour, enzyme activity, favour, and sweetness and for nutritional amelioration. In bakery products, diastatic malts are used as dough conditioners, whereas nondiastatic malts are used to provide a colour and strong favours.

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Arts, M. J., Grun, C., de Jong, R. L., Voss, H. P., Bast, A., Mueller, M. J., and Haenen, G. R. 2007. Oxidative degradation of lipids during mashing. Journal of Agricultural and Food Chemistry 55(17):7010–7014. Autio, K., Simoinen, T., Suortti, T., Salmenkallio‑Marttila, M., Lassila, K., and Wilhelmson, A. 2001. Structural and enzymic changes in germinated barley and rye. Journal of the Institute of Brewing 107(1):19–25. Bamforth, C. W. 1985. Te foaming properties of beer. Journal of the Institute of Brewing 91(6):370–383. Bamforth, C. W. 2004. Te relative signifcance of physics and chemistry for beer foam excellence: Teory and practice. Journal of the Institute of Brewing 110(4):259–266. Bamforth, C. W. 2009. Current perspectives on the role of enzymes in brewing. Journal of Cereal Science 50(3):353–357. Bamforth, C. W. 2017. Progress in brewing science and beer production. Annual Review of Chemical and Biomolecular Engineering 8:161–176. Bamforth, C. W., and Martin, H. L. 1981. Β‑glucan and β‑glucan solubilase in malting and mashing. Journal of the Institute of Brewing 87(6):365–371. Baranwal, D. 2017. Malting: An indigenous technology used for improving the nutritional quality of grains – A review. Asian Journal of Diary and Food Research 36:179–183. Blanco, C. A., Rojas, A., and Nimubona, D. 2007. Efects of acidity and molecular size on bacteriostatic properties of beer hop derivates. Trends in Food Science and Technology 18(3):144–149. Bond, J., Capehart, T., Allen, E., and Kim, G. 2015. Boutique Brews, Barley, and the Balance Sheet: Changes in Malt Barley Industrial Use Require an Updated Forecasting Approach. Washington, DC: Economic Research Division, United States Department of Agriculture, 18–23. Briggs, D. E., Wadeson, A., Statham, R., and Taylor, J. F. 1986. Te use of extruded barley, wheat and maize as adjuncts in mashing. Journal of the Institute of Brewing 92(5):468–474. Broderick, H. M., Canales, A. M., and Coors, J. H. 1977. El cervecero en la práctica: un manual para la industria cervecera. 2nd ed. USA: Asociación de Maestros Cerveceros de las América. Coghe, S., Gheeraert, B., Michiels, A., and Delvaux, F. R. 2006. Development of Maillard reaction related characteristics during malt roasting. Journal of the Institute of Brewing 112(2):148–156. Delcour, J. A., Hennebert, M. M., Vancraenenbroeck, R., and Moerman, E. 1989. Unmalted cereal products for beer brewing. Part I. Te use of high percentages of extruded or regular corn starch and sorghum. Journal of the Institute of Brewing 95(4):271–276. Edney, M. J., and Izydorczyk, M. S. 2003. Malt | Malt types and products. In: B. Caballero, P. Finglas, F. Toldra, Encyclopedia of Food Sciences and Nutrition. US: Academic Press, 3671–3677.

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Georg‑Kraemer, J. E., Mundstock, E. C., and Cavalli‑Molina, S. 2001. Developmental expression of amylases during barley malting. Journal of Cereal Science 33(3):279–288. Guido, L. F., Boivin, P., Benismail, N., Gonçalves, C. R., and Barros, A. A. 2005. An early development of the nonenal potential in the malting process. European Food Research and Technology 220(2):200–206. Guido, L. F., Curto, A. F., Boivin, P., Benismail, N., Gonçalves, C. R., and Barros, A. A. 2007. Correlation of malt quality parameters and beer favor stability: Multivariate analysis. Journal of Agricultural and Food Chemistry 55(3):728–733. Ha, K. S., Jo, S. H., Mannam, V., Kwon, Y. I., and Apostolidis, E. 2016. Stimulation of phenolics, antioxidant and α‑glucosidase inhibitory activities during barley (Hordeum vulgare L.) seed germination. Plant Foods for Human Nutrition 71(2):211–217. Hansen, B., and Wasdovitch, B. 2005. Malt ingredients in baked goods. Cereal Foods World 50(1):18. Harrison, M. A. 2009. Beer/brewing. In: Schaechter, M. (ed.), Encyclopedia of Microbiology. 3rd ed. Oxford: Academic Press, 23–33. Hirota, N., Kuroda, H., Takoi, K., Kaneko, T., Kaneda, H., Yoshida, I., Takashio, M., Ito, K., and Takeda, K. 2006. Brewing performance of malted lipoxygenase‑1 null barley and efect on the favor stability of beer. Cereal Chemistry 83(3):250–254. Hoseney, R. C. 1994. Principles of Cereal Science and Technology. 2nd ed. USA: American Association of Cereal Chemists, Inc., pp. 179–182. Iren, Leder. 2004. Sorghum and millets. In: Füleky, G. (ed.), Cultivated Plants, Primarily as Food Sources. Oxford, UK: Encyclopedia of Life Support Systems (EOLSS), Developed under the Auspices of the UNESCO Eolss Publishers. Iserentant, D. 2003. Beers: Technological innovations in brewing. In: Lea, A. G. H., and Piggott, J. (eds.), Fermented Beverage Production. 2nd ed. New York: Springer, 41–58. Kochevenko, A., Jiang, Y., Seiler, C., Surdonja, K., Kollers, S., Reif, J. C., Korzun, V., and Graner, A. 2018. Identifcation of QTL hot spots for malting quality in two elite breeding lines with distinct tolerance to abiotic stress. BMC Plant Biology 18(1):106. Kok, Y. J., Ye, L., Muller, J., Ow, D. S. W., and Bi, X. 2019. Brewing with malted barley or raw barley: What makes the diference in the processes? Applied Microbiology and Biotechnology 103(3):1059–1067. Kokić, B., Lević, J., Chrenková, M., Formelová, Z., Poláčiková, M., Rajský, M., and Jovanović, R. 2013. Infuence of thermal treatments on starch gelatinization and in vitro organic matter digestibility of corn. Food and Feed Research 40(2):93–99. Kühbeck, F., Back, W., and Krottenthaler, M. 2006a. Infuence of lauter turbidity on wort composition, fermentation performance and beer quality—A review. Journal of the Institute of Brewing 112(3):215–221.

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Kühbeck, F., Back, W., and Krottenthaler, M. 2006b. Infuence of lauter turbidity on wort composition, fermentation performance and beer quality in large‑scale trials. Journal of the Institute of Brewing 112(3):222–231. Lewis, M. J., and Young, T. W. 2001. Malting technology: Malt, specialized malts and nonmalt adjuncts. In: M. J. Lewis, T. W. Young, Brewings. 2nd ed. New York: Springer, 163–190. Ohlmeyer, D. W., and Matz, S. A. 1970. In: Matz, S. A. (ed.), Cereal Technology. Westport, CT: Avi, 173–220. Pires, E., and Brányik, T. 2015. An overview of the brewing process. In: E. Pires, T. Brányik, Biochemistry of Beer Fermentation. Springerbriefs in Biochemistry and Molecular Biology. 1st ed. Springer International Publishing. USA: Springer, 1–9. Plessi, M., and Papotti, G. 2003. Vinegar. In: C. W. Bamforth, R. E. Ward, Te Oxford Handbook of Food Fermentations. New York: Oxford University Press. Sammartino, M. 2015. Enzymes in brewing. MBAATQ 52(3):156–164. Scott, R. W. 1972. Te viscosity of worts in relation to their content of β‑glucan. Journal of the Institute of Brewing 78(2):179–186. Simpson, W. J., and Smith, A. R. W. 1992. Factors afecting antibacterial activity of hop compounds and their derivatives. Te Journal of Applied Bacteriology 72(4):327–334. Sovrano, S., Buiatti, S., and Anese, M. 2006. Infuence of malt browning degree on lipoxygenase activity. Food Chemistry 99(4):711–717. Stewart, G. G. 2013. Biochemistry of brewing. In: Eskin, N. A. M., and Shahidi, F. (eds.), Biochemistry of Foods. 3rd ed. San Diego, CA: Academic Press, 291–318. Verhagen, L. C. 1994. Beer favour. In: J. R. Piggott, A. Paterson, Understanding Natural Flavors. Boston, MA: Springer, 211–227. Wackerbauer, K., Meyna, S., and Marre, S. 2003. Hydroxy fatty acids as indicators for ageing and the infuence of oxygen in the brewhouse on the favour stability of beer. Monatsschrift fur Brauwissenschaft 56(9/10):174–178. Walker, C. K., and Panozzo, J. F. 2016. Genetic characterization, expression and association of quality traits and grain texture in barley (Hordeum vulgare L.). Euphytica 212:1–15. Wang, S., Zhang, X., Wang, S., and Copeland, L. 2016. Changes of multi‑ scale structure during mimicked DSC heating reveal the nature of starch gelatinization. Scientifc Reports 6:28271. Zentella, R., Yamauchi, D., and Ho, T.‑H. D. 2002. Molecular dissection of the gibberellin/abscisic acid signaling pathways by transiently expressed RNA interference in barley aleurone cells. Te Plant Cell 14(9):2289–2301.

9 P RO DUCT F ORMUL ATION

9.1 Introduction

Te bakery industry is one of the largest organized food industries all over the world, and in particular biscuits, crackers, and cakes are one of the most popular products because of their convenience, ready‑ to‑eat form, and long shelf life (Yaqoob et al., 2018). Wheat is the most important cereal crop used for the preparation of bakery products because of its better baking performances as compared to other cereals. However, wheat is low in lysine, methionine, and threonine, and the protein quality is inferior when compared with other cereal grains. Terefore, wheat‑based products may be fortifed with proteins, fbres, vitamins, and minerals to meet the specifc needs of the target groups and vulnerable sections of the population that are malnourished. Apart from extending the availability of wheat products by fortifying with other cereal grains, baked products may act as nutrition carriers (Shaif et al., 2016, 2017). Te food industry is therefore faced with the challenge of producing novel barley‑based foods that are not only healthy but also that will satisfy the consumer’s needs. Barley is one of the most genetically diverse cereal grains (Baik and Ullrich, 2008). Being a rich source of dietary fbres, β‑glucan, phenolic compounds, etc., barley has the potential to be used in a number of bakery goods as a functional component. Barley β‑glucan has shown a link between its regular consumption and a number of health benefts. High‑fbre, high‑complex carbohydrate diets have been useful in regulating blood lipids, blood glucose, and insulin response factors that are signifcant in the prevention and treatment of coronary heart disease and diabetes (Knuckles et al., 1997). Barley may be processed and consumed as ingredients in diversifed foods. Terefore, there is an interesting opportunity to incorporate a combination of wheat–barley four blends into bakery or other 16 5

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food products to improve their nutritional properties. Barley products have been successfully incorporated into many food products, i.e. breads (Collar and Angioloni, 2014), chapattis (Sidhu et al., 1990), Turkish bazlama bread (Basman and Köksel, 1999), wheat breads (Collar and Angioloni, 2014; Sullivan et al., 2011; Dhingra and Jood, 2001), sponge cake (Gupta et al., 2009; Yakoob et al., 2018), pastas (Macroni et al., 2001; Izydorczyk and Dexter, 2016), biscuits (Drakos et al., 2019), etc. (Table 9.1). Sensory characteristics (e.g., appearance, colour, textures, favour), loaf volume and weight, mixing time, water absorption, gluten content, rheological properties, and instrumental texture profle analysis are the measured characteristics for bakery products. Te addition of barley to wheat caused physical, chemical, and rheological changes in the dough and bread characteristics. Before consumption, the colour and appearance of food and food products are the frst factors that are considered. Te discolouration of bread (dark grey colour) by barley is one of the obstacles that prevent the use of barley in food products. Enzymatic and nonenzymatic browning reactions are responsible for barley discolouration in food products. Barley grains have a higher phenolic compound content of 0.2–0.4% than other cereal grains (Bendelow and LaBerge, 1979). In other cereal grains, the phenolic compounds are mainly found in the hull, testa, and aleurone (Nordviskt et al., 1984), whereas in the barley kernel they are dispersed throughout (Jerumanis et al., 1976) due to which barley four contains appreciable amount of phenolic compound. Enzymatic discolouration is a consequence of oxidation of phenolic compounds, by polyphenol oxidase (PPO), which are converted into o‑quinones (Mcevily et al., 1992; Sapers, 1993), and this triggers the generation of dark pigments. In nonenzymatic reactions, the polymerization of endogenous phenolic compounds is the cause of barley four discolouration. 9.2 Breads

Breads are characterized by a light, golden brown “crust,” a dry thin layer which encloses a soft, sponge‑like cellular structure (Cauvain and Young, 2010). Compared with wheat four, barley four is less able to form a gluten complex upon hydration and mixing, owing to the

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Table 9.1 Utilization of Barley in Product Formulation PRODUCTS

INGREDIENTS

Biscuits

Barley + wheat

Biscuits

Barley + buckwheat + wheat four Raw and sprouted barley + wheat four

Cakes

Bread

Barley + wheat

Bread

Barley + wheat

Chapatti

Barley + wheat

Bread

Barley middling + wheat

Spaghetti

Barley four + semolina

Sponge cake

Barley + wheat

RESULTS The substitution of barley four resulted in softer and darker biscuits, with greater total phenolics content and antioxidant activity.

REFERENCES Drakos et al. (2019)

Hussain and Kaul (2018) Cakes prepared from sprouted barley four were nutritionally superior, softer, and frmer than both control and raw barley four-based cakes. As the concentration of barley four (0–25%) was increased in wheat bread, protein, gluten contents, and crumb density decreased whereas the ash content, enzyme activity, and porosity were increased. Blending wheat with 40% of high β-glucan barley resulted in bread with a high level of dietary fbre as compared to commercial barley and regular wheat bread. Increasing the level of barley four increased total phenolic content, antioxidant activity, and reducing power and total favonoid content in the four blends. Upon baking, an increase in antioxidant and metal chelating activity and decrease in phenolic and favonoids content were observed. Addition of barley middling up to 30% in wheat bread increased dietary fbres, but quality factors such as loaf volume and textural properties were not signifcantly affected. Better sensorial characteristics, i.e. higher frmness and lower bulkiness were also observed for barley spaghetti. Incorporation of barley four (20%) into wheat four for preparing cake was found to be optimum, containing a high amount of β-glucan, iron, calcium, and zinc, and the highest sensory scores.

Yakoob et al. (2018)

Al-Attabi et al. (2017)

Collar and Angioloni (2014)

Sharma and Gujral (2014)

Sullivan et al. (2011)

Lamacchia et al. (2011) Gupta et al. (2009)

(Continued )

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Table 9.1 (Continued)

Utilization of Barley in Product Formulation

PRODUCTS

INGREDIENTS

RESULTS

Flatbread

Barley fbre-rich fraction + wheat

Tortillas

Whole barley four (237-µm, 131-µm, and 68-µm particle size) + wheat four Hull-less barley four + wheat

Incorporation up to 20% barley fbre-rich fraction provides health benefts by increasing dietary fbres and by decreasing starch digestibility with overall acceptability of fat bread. Tortillas made with the largest particle size were the most similar in protein content, texture, and favour when compared with tortillas made with refned bread four.

Noodles

Bread

Barley + wheat

Tarhana

Hulled and hull-less barley + yeast + yogurt + spices

Bread

Barley β-glucanenriched fractions + wheat four

Bread

Barley + wheat

Incorporating up to 40% four from hull-less barley genotypes with normal-amylose, waxy, zero-amylose waxy, and high-amylose starch into a 60% extraction Canada Prairie Spring White wheat four had a negative impact on white salted noodles colour and appearance, as evident from decreased brightness, increased redness, and more visible specking. Incorporation of 30–45% barley four into Jordanian wheat bread did not affect consumer acceptability, but further addition of barley four content resulted in harder and darker bread loaves. The results showed that barley four may be used alone or together with wheat four in tarhana production with a relatively high β-glucan content. Barley may be used as a source of a high-value fbre for reducing the glycemic index of traditional wheat-based foods such as bread, without negatively affecting their sensory characteristics. Incorporation of barley four to wheat signifcantly increased the dietary fbre and β-glucan and maintained acceptable organoleptic characteristics also.

REFERENCES Izydorczyk et al. (2008)

Prasopsunwattana et al. (2009)

Lagassé et al. (2006)

Ereifej et al. (2006)

Erkan et al. (2006)

Cavallero et al. (2002)

Dhingra and Jood (2001)

(Continued )

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Table 9.1 (Continued) PRODUCTS

Utilization of Barley in Product Formulation

INGREDIENTS

Pastas

Barley pearling by-products + semolina + gluten

Pasta

β-Glucan-rich barley four + semolina Barley + wheat

Chapatti

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RESULTS Although pastas were darker in colour, they possessed higher dietary content and β-glucan with good cooking qualities with regard to stickiness, bulkiness, frmness, etc. Acceptable sensorial score.

Similar farinograph dough characteristics for wheat four (100%) and barley four (10%) added to wheat four were observed and further addition of barley four to wheat decreased mixing time, dough stability, and chapatti quality.

REFERENCES Marconi et al. (2000)

Knuckles et al. (1997) Anjum et al. (1991)

substitution of gliadins with hordeins (Arendt and Zannini, 2013). Many studies reported that addition of barley negatively afected dough characteristics, loaf volume, and the crumb colour of breads, which may be due to the absence of gluten protein and the high content of phenolic compounds and fbre content. Not only dilution of wheat gluten but insoluble fbres present in barley also interfere in the formation of the gluten network during dough formation (Gill et al., 2002; Salmenkallio‑Marttila et al., 2001) due to which gas cell rupture (Courtin and Delcour, 2002) and bread volume is reduced (Anjum et al., 1991). Nifenegger (1964) reported that incorporation of barley up to 75% decreased the loaf volume and provides poor favour and texture. Incorporation of barley four up to 15% increased dietary fbres and β‑glucan content and maintained the organoleptic and nutritional characteristics of wheat breads (Dhingra and Jood, 2001). Several investigations have focused on the proportion of barley four that can be blended with wheat four to produce acceptable breads (Holtekjølen et al., 2008). Cavallero et al. (2002) used barley four and two (1→3,1→4)‑β‑glucan‑enriched fractions, a sieved fraction, and a water‑extracted fraction, for bread making. Tey reported that barley may be used as a source of a high‑value fbre for reducing the glycemic index of traditional wheat‑based foods such as bread,

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without negatively afecting their sensory characteristics. Ereifej et al. (2006) reported that the incorporation of 30–45% barley four into Jordanian wheat bread did not afect consumer acceptability, but further addition of barley four results in harder and darker bread loaves. Sullivan et al. (2011) incorporated barley middling in wheat bread to increase dietary fbres and reported that quality factors such as loaf volume and textural properties were not signifcantly afected by the addition of up to 30% barley middling while the fbre and β‑glucan contents of the barley‑containing breads were increased. Collar and Angioloni (2014) found that blending wheat with 40% of high β‑glucan barley resulted in bread with a high level of dietary fbre as compared to commercial barley and regular wheat bread. Al‑Attabi et al. (2017) incorporated barley four (0–25%) in wheat fours bread and stated that as the concentration of barley four was increased in wheat bread, protein, gluten contents, and crumb density decreased, whereas the ash content, enzyme activity, and porosity were increased. 9.3 Flatbreads

Flatbreads are the frst baked cereal products and the oldest of all bread products and are usually made from wheat four, but mixtures with corn, rye, millet, and barley are common (Miskelly, 2017). Chapattis, roti, poori, and parathas are common single‑layered fat breads of the Indian subcontinent. Tey are produced with or without dough fermentation, and formation of bubble during mixing is of less concern (Baik, 2016). In the production of Turkish fat bread, Basman and Köksel (1999) observed a negative infuence in sensory properties, including the colour, texture, taste, and aroma, when barley four was added up to 40% in the bread formulation. To increase the dietary fbre content, Izydorczyk et al. (2008) supplemented a barley fbre‑rich fraction in two‑layer fat bread and reported that incorporation up to 20% barley fbre‑rich fraction provides health benefts by increasing dietary fbres and by decreasing starch digestibility with overall acceptability of fat bread. Chapattis are another type of fat bread and a good option for utilizing barley in baked foods. A healthy person consumes fve to six chapattis in a day, and this quantity can deliver the required (3 g)

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daily requirement of β‑glucan and antioxidants if part of the wheat four is replaced with barley four (Sharma and Gujral, 2014). Tey replaced wheat four with barley at diferent levels, i.e. 28, 56, and 84 g/100 g to prepare chapattis and concluded that increasing the level of barley four increased the total phenolic content, antioxidant activity, reducing power and total favonoid content in the four blends. Upon baking, an increase in antioxidant and metal chelating activity and decrease in phenolic and favonoids content were observed. Anjum et al. (1991) observed a farinograph dough characteristic of wheat four (100%) and barley four (10%), when added to wheat four, and reported that further addition of barley four to wheat decreased mixing time, dough stability, and chapatti quality. Chapatti prepared with up to 20% barley addition showed higher extensibility (Gujral and Pathak, 2002). Tortilla is a fat, round, unfermented bread produced from wheat four. Tey are used as wraps for carrying vegetable and meat fllings and may be fortifed with whole grains without impairing their quality as sponge crumb structure and volume are not signifcant concerns for tortilla quality (Baik, 2016). Prasopsunwattana et al. (2009) enriched wheat tortillas with whole barley four of diferent particle sizes of 237 µm, 131 µm, and 68 µm and reported that tortillas made with the largest particle size were the most similar in protein content, texture, and favour when compared with tortillas made with refned bread four. 9.4 Noodles and Pastas

Whole and fbre‑rich cereal grains have generated interest in the formulation of novel pasta products containing whole wheat and supplemented with barley four or barley milling fractions. Because of the high dietary fbre (15.2–16.1%) and β‑glucan (4.3–5.0%) content, barley may be incorporated in pasta and considered as a healthy food product (Izydorczyk and Dexter, 2016). Barley fractions have also been incorporated into pasta and noodles (Lagassé et al., 2006; Izydorczyk et al., 2005). Despite the numerous health benefts of eating barley and its great potential for use in various food products, food use of barley is extremely low compared with other cereal grains. Te

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limited food use of barley is probably due to cultural eating practices as well as the undesirable colour and unfamiliar favour of barley‑based food products (Quinde et al., 2004). Bright yellow colour, absence of dark specks, smooth and nonsticky surface, structural integrity, and high degree of frmness and elasticity are the characteristics of noodles (Delcour and Hoseney, 2010; Pomeranz, 1987; Antognelli, 1980). Because of the absence of gluten, dark colour, reduced frmness and elasticity, and increased cooking loss are the major concerns in the production of barley pastas. In the 1970s, the Korean government took initiatives to expand the use of barley as food, and many research eforts were made to formulate barley noodles (Chang and Lee, 1974; Cheigh et al., 1976; Kim et al., 1973; Ryu et al., 1977). Glyceryl monostearate and sodium polyacrylate may be used for preparing barley noodles (Chang and Lee, 1974; Kim et al., 1973). Chang and Lee (1974) suggested that for sheet and dried noodle formations, barley four may be substituted 100%, and their textural characteristics may be improved by the addition of glyceryl monostearate and sodium polyacrylate. A study conducted by Kim et al. (1973) concluded that substitution of barley (50%), wheat (40%), and soy four (10%) may be used for maintaining the acceptable characteristics of soft bite noodles. Ryu et al. (1977) reported that substitution of barley up to 20% exhibited acceptable sensory characteristics of instant noodles, and addition up to 40% may be achieved by using xanthan gum (Cheigh et al., 1976). Te colour of yellow alkaline noodles deteriorated with more visible specks present when enriched with up to 40% hull‑less four (Hatcher et al., 2005). Lagassé et al. (2006) prepared fresh and dried white salted noodles by incorporating up to 40% four from hull‑less barley genotypes with normal amylose, waxy, zero‑amylose waxy, and high‑amylose starch into 60% extraction Canada Prairie Spring White wheat four and claimed that the addition of hull‑less barley four (enriched with β‑glucans to satisfy the FDA (2005) health claim requirement) had a negative impact on the colour and appearance of white salted noodles, as evident from decreased brightness, increased redness, and more visible specking. Te quality characteristics of pasta depend on the ability of the pasta to soak up moisture during cooking (Brennan and Newton,

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2004). Knuckles et al. (1997) prepared pasta with 20% β‑glucan‑rich barley four with an acceptable sensorial score. Marconi et al. (2000) formulated pasta by the addition of barley pearling by‑products, semolina, and wheat gluten and concluded that pastas were darker in colour but possessed higher dietary content and β‑glucan with good cooking qualities with regard to stickiness, bulkiness, frmness, etc. Dexter et al. (2005) substituted four hull‑less barley genotypes with zero, normal, and high‑amylose starch into semolina at up to 40%. When hull‑less barley replaced semolina at 40%, colour was adversely afected, but when subjected to pearling (15%) before milling, colour of hull‑less barley four‑semolina blends was reasonably acceptable. Replacement of semolina with zero‑amylose starch barley four made spaghetti less frm. Addition of fbre‑rich fraction from pearled barley made spaghetti of a darker colour but did not impact frmness. When fbre‑rich fractions derived from milling of pearled barley were introduced in sufcient quantities to raise the content of β‑glucan in the pasta to 2%, colour was reasonably acceptable and might meet the expectations of health‑conscious consumers. Dexter et al. (2005) found that pasta colour deteriorated when durum wheat semolina was enriched with hull‑less barley roller milling fractions. Lamacchia et al. (2011) prepared spaghetti from barley four and semolina and observed a decrease of both S–S bonds and –SH free groups and the development of protein‑based polymers of high molecular weight during pasta making. Te substitution of semolina with barley four increased cooking time due to β‑glucan hydrophilicity and its competition with starch for water. Better sensorial characteristics, i.e. higher frmness and lower bulkiness, were also observed for barley spaghetti. 9.5 Biscuits and Cookies

Te popularity of baked foods, such as biscuits and cookies, to deliver functional dietary fbre has been increasing. Te replacement of traditional food ingredients like wheat with high‑fbre alternatives, such as barley four in cookie and biscuit manufacturing, may be nutritious and benefcial and contribute to increasing the daily dietary intake. Incorporation of barley four into wheat four dilutes the gluten protein of wheat but high gluten content is not required for making cookies

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and biscuits, but being a rich source of phenolic compounds, β‑glucan, dietary fbres etc., barley may be added as a functional ingredient to enhance the nutritional characteristics in bakery products. Frost et al. (2011) explored the possibility of using barley four as an ingredient to incorporate soluble fbre (β‑glucan) in chocolate‑chip cookies. Tey concluded that as the level of barley four was increased, an enhancement in baked‑barley aroma and favour, thickness, colour intensity, dryness, and graininess was observed. Te results revealed that cookies made with 30% (0.5 g β‑glucan/serving) and 50% (0.8 g β‑glucan/ serving) barley four substitution were comparable in liking to the control (0% substitution) cookie and a commercial cookie. Rasco et al. (1990) reported that the crust colour of breads made with barley distillers’ grain was darker and redder. Te increased substitution level led to darker bakery goods when wheat four was combined with other cereals. Gupta et al. (2011) replaced wheat four partially with barley four and observed that as the concentration of barley four was increased, the colour of biscuit changed from pale cream to golden brown. Ikuomola et al. (2017) replaced wheat with malted barley bran to produce cookies with high protein, ash, and fbre contents as this could make a signifcant contribution to the nutrient intake by consumers who are likely to be children. Alka et al. (2017) developed cookies from barley four, which were subjected to soaking, popping, and malting. Te highest score of overall acceptability was observed for wheat four cookies, and malted four cookies were found to have the highest contents of crude protein, crude fbre, dietary fbre, and soluble fbre. Te biscuit‑making performance of four depends on both its botanical source and particle size. Because of changing lifestyles and the demand for convenience and healthy food, multigrain bakery products are also gaining interest. Multigrain blends help to mix diferent whole grains to maximize their nutritional, functional, and sensory characteristics. A blend of wheat, barley (20%), and buckwheat increases iron, calcium, and zinc content (Hussain et al., 2018) and fbre, fat, ash, and carbohydrate content of biscuits (Hussain and Kaul, 2018). Lalit and Kochhar (2018) developed barley‑based bakery products and recommended them for nutritional and health benefts because they are cost‑efective, nutritious, and help to manage diferent diseases. Drakos et al. (2019) produced wheat and barley four by

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jet milling commercially and replaced wheat four with barley at 0, 10, 20, 30, and 40%, and this substitution resulted in softer and darker biscuits, with greater total phenolics content and antioxidant activity compared to biscuits with 100% wheat. 9.6 Cakes

Cakes are one of the most popular products because of their convenience, ready‑to‑eat form, and long shelf life. Incorporation of barley improves the nutritional properties and colour of cakes; therefore, it may be a good option for production of fortifed cakes (Yakoob et al., 2018). To determine the efect of blending raw and sprouted barley four on cake production from refned wheat four, Yakoob et al. (2018) added raw and sprouted barley four in wheat four and reported that cakes prepared from sprouted barley four were nutritionally superior, softer, and frmer than both control and raw barley four‑based cakes, but sprouting drastically decreased the sensory characteristics. All cakes were microbiologically safe for human consumption. Tey further reported that sprouting of cereals may be an alternative to improve the nutritional and physical characteristics of cakes. Incorporation of barley four (10, 20, 30, and 40%) in wheat four sponge had a signifcant anti‑staling efect on cakes with an enhancement in mineral content and frm and softer texture than control wheat cakes (Gupta et al., 2009). 9.7 Tarhana

Fermented cereal and yogurt mixtures play an important role in the diets of many people in the Middle East, Asia, Africa, and some parts of Europe (Ibanoglu and Ibanoglu, 1999). Tarhana is a popular traditional fermented food product in Turkey and prepared by mixing yogurt, wheat four, yeast, and a variety of vegetables and spices followed by fermentation for 1–7 days. Lactic acid bacteria and yeast are responsible for the acid formation during fermentation. After fermentation, the mixture is sun dried and ground (Erkan et al., 2006). Tarhana has an acidic and sour taste with a yeasty favour and is used for soup making (Ibanoglu and Ibanoglu, 1997). Tarhana

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supplemented with barley four is reported to be a good source of minerals, phenolics, as well as antioxidant activity and considered as a functional food. Erkan et al. (2006) utilized hulled and hull‑less barley in tarhana formulations in order to produce a new food product with a relatively high β‑glucan content. Te results showed that barley four used alone or together with wheat four in tarhana production resulted in acceptable soup properties in terms of most of the sensory properties. Karademir and Yalçın (2019) prepared cornelian cherry tarhana using whole grain hull‑less barley four and reported an increase in ash, protein, fat, and total dietary fbre contents. 9.8 Tortillas

A tortilla is a fat, round, unfermented bread produced from wheat four or lime‑cooked maize. Sorghum is used alone or in mixtures with maize for tortillas in parts of Central America (Rooney et al., 2004). Ames et al. (2006) used barley four fractions to make tortillas and reported that barley tortillas maintained their texture and nutritional content for at least 29 days of frozen storage, and 90% of the consumer panelists scored the barley tortillas highly in terms of texture and taste, when compared with their wheat counterpart. Incorporation of whole barley four into tortillas is an approach to delivering whole grains and soluble fbre (Toma et al., 2008). 9.9 Barley Tea

Tea is a widely consumed beverage, and for a number of third‑world countries tea is a major plantation crop that earns foreign exchange by way of exports. Tea is now in its high‑impact specialization, in all its forms. Te constant innovations are making this beverage more popular than ever (Rao and Ramalakshmi, 2011). A patent assigned to Hatsuzawa (1973) describes the fortifcation of tea with a combination of roasted barley and caramel from roasted sugar. A barley tea of improved favour is obtained. Another patent assigned to Horie Food Co. (1973) describes barley tea production in which roasted barley grains are leached to obtain their vitamins, which are added to barley tea in bottles and heat sterilized.

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9.10 Conclusions

Barley and barley products are receiving interest from food manufacturers, food consumers, food technologists, nutritionists, researchers, etc., because of the numerous health benefts which are associated with the consumption of barley. With increasing global concerns over food‑ related health issues, the demand for food which provides not only energy and nutrients but also health benefts is growing day by day. Being a rich source of dietary fbres, β‑glucan, phenolic compounds, minerals, and tocols, barley may be considered as an ideal ingredient for formulated functional foods with proven health benefts.

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Index A

B

Acetates, 69 Acetylation method, 127, 134–135 Acid hydrolysis, 127, 128, 136 Albumin, 10 Aleurone, 8, 10 Alkylresorcinols, 35, 49, 52 α-acids, 160 Amber malt, 155 Amylopectin, 8, 99 Amylose, 8, 99, 100 Annealing process, 124, 126–128, 130–131 Anthocyanins, 46 Arabinoxylans, 8, 9, 10 Arithmetic mean diameter (Da), 22 Aspergillus awamorinakazawa, 85 A-type starch granule, 102 a* value, 28 Avenanthramides, 35

Barley; see also individual entries antioxidants, 42–44 characteristics, 24–25 cultivation, 2 grain structure, 2–6 history, 1–2 production, 2–4 uses, 13 Barley tea, 176 Beer brewing process, 156, 157 bottling, 161 carbonation, 161 fermentation/pitching, 160 fnishing, 161 hops addition, 159–160 mashing, 158–159 maturation, 161 milling, 156–158 composition, 156, 158

18 3

18 4

IN D E X

malting process, 156 Benzoic acid, 40 β-acids, 160 β-D-glucan, 83 β-glucans, 10, 39, 49, 53 action mechanism, 68–69 extraction of, 66, 67 health benefts anti-carcinogenic behaviour, 71–72 blood glucose/diabetes reduction, 70–71 body weight management and obesity, 72 cholesterol reduction, 69–70 hypertension, 71 immunity, 72–73 mechanism of, 69, 70 Bioactive compounds, 35 classifcation favonoids, 38, 42–50 phenolic acids, 38, 39–42 tocopherols and tocotrienols, 38 Biscuits, 173–175 Black malt, 155 Breads, 166, 169–170 Breakdown viscosity (BV), 30, 107 Brown malt, 155 B-type starch granule, 102 Bulk density, 23 Butyrates, 69 BV, see Breakdown viscosity b* value, 28 C Cakes, 175 Caramel malt, 154 Carbohydrates composition, 8, 9 Carotenoids, 47, 50–51 Cellulose, 8–10

Cereal, 2, 11, 35, 53 carotenoids, 50–51 phenolic compounds in, 40, 41 Chemical composition, 5–8 dietary fbre, 8–10 lipids, 11 minerals, 12 phenolic compounds, 12–13 protein, 10–11 starch, 8, 9, 100–102 vitamins, 11–12 Chemical modifcations, starch acetylation, 134–135 acid hydrolysis, 136 cross-linking, 137 dual modifcation, 138–139 octenyl succinic anhydride, 136 oxidation, 135 succinylation, 137–138 Chocolate malt, 155 Cinnamic acid, 40, 42 Condensed tannins, 51 Confocal scanning microscopy, 104 Cookies, 173–175 Corn, 36 Cross-linking method, 127, 128, 137 Cultivation, 2 D Degree of substitution (DS), 135 Dehulling, 80–81 Delphinidin 3-glucoside, 47 Dg, see Geometric mean dimension Diastatic malt, 155 Dietary fbres, 8–10, 35, 68, 71 insoluble dietary fbre, 9 soluble dietary fbre, 9, 65, 66, 83, 88 Diferential scanning calorimetry (DSC), 30, 111, 113

IN D E X

DS, see Degree of substitution DSC, see Diferential scanning calorimetry Dual modifcation method, 123–124, 138–139 E EC, see Emulsion capacity Elavane, 45 Emulsion capacity (EC), 29 Emulsion stability (ES), 29 Endosperm, 5, 8, 11, 12 Enzymatic discolouration, 166 Enzymatic modifcations, 139–140 ES, see Emulsion stability Extrusion, 87–88 F FC, see Foaming capacity FDA, see Food and Drug Administration Fermentation, 68, 69, 84–86 Ferulic acid, 42 FFAR2, see Free fatty acid receptor 2 Filamentous fungi, 85 Final viscosity (FV), 30, 107 Flatbreads, 170–171 Flavanols, 45 Flavones, 45 Flavonoids, 35, 38, 42–50 Flavonol, 45 Foaming capacity (FC), 29 Foaming stability (FS), 29 Food and Drug Administration (FDA), 65, 137 Free fatty acid receptor 2 (FFAR2), 72 FS, see Foaming stability

18 5

Functional components action mechanism, 36–38 alkyleresorsinols, 52 β-glucan, 53 bioactive compounds classifcation, 38 in whole-grain cereals, 39 carotenoids, 50–51 favonoids, 42–50 lignans, 51–52 phenolic acids, 39–42 phytosterol, 52–53 tannins, 51 tocopherols, 49–50 whole-grain cereals bioactive compounds, 39 health benefts of, 36 Functional properties, 28–29 FV, see Final viscosity G GA, see Gibberellic acid γ-oryzanol, 39 Gelatinization, 111, 159 Gel-permeation chromatography (GPC), 100 Geometric mean dimension (Dg), 22 Germination, 82–84, 150–151 GI, see Glycaemic index Gibberellic acid (GA), 151 Globulin, 10, 11 Glucagon-like-peptide-1 (GLP-1), 72 Glutelin, 10 Glycaemic index (GI), 113 GPC, see Gel-permeation chromatography Grain structure, 2–6 Green malt, 152

18 6

IN D E X

H

K

Heat-moisture treatment (HMT), 124, 126, 128, 130, 131 HHP, see High-pressure processing High-performance size-exclusion refractive index (HPSEC-RI), 99 High-pressure processing (HHP), 132 High-temperature short-time (HTST) process, 87, 130 HMT, see Heat-moisture treatment Hordein, 10, 11 Hordeum spp. H. distichon, 1 H. hexastichon, 1 H. vulgare, 1 (see also Barley) H. zeocriton, 1 HPSEC-RI, see High-performance size-exclusion refractive index HTST, see High-temperature short-time process Hunter color characteristics, 27–28 Hydrolysable tannins, 51 Hydrothermal treatment annealing, 130–131 heat-moisture treatment, 131 Hydroxybenzoic acids, 39 Hydroxybenzoic derivatives, 38 Hydroxycinnamic acids, 39, 40 Hydroxycinnamic derivatives, 38 Hypercholesterolemia, 69 Hypertension, 71

Kilned malt, 155

I Insoluble dietary fbre, 9 Iso-acids, 160 Isofavone, 44, 47

L Lignans, 49, 51–52 Lignin, 6, 84 Lipids, 11 Loss modulus (G″), 110 Loss tangent, 110 L* value, 27–28 M Macrophages, 72, 73 Malt and malt products amber malt, 154 bakery goods, 155–156 beer, 156–161 black malt, 155 brown malt, 155 caramel malt, 154 chocolate malt, 155 drying process, 151–152 extracts and syrups, 152–153 malted milk powder, 156 malting process, 149–151 malt vinegar, 161 Munich malt, 154 pale ale malt, 154 pale lager malt, 154 Vienna malt, 154 Malted milk powder, 156 Malting process, 149–151 Malt vinegar, 161 Mammalian lignans, 52 Micronization, 126, 128, 132–133 Milling, 23–27, 82 Minerals, 12 Munich malt, 154

IN D E X

N Nondiastatic malt, 155, 156 Non-starch polysaccharide (NSPs), 9 Nonthermal physical modifcation, 131–132 high-pressure processing (HHP), 132 micronization, 132–133 pulse electric feld (PEF), 133–134 ultrasonication, 133 Noodles, 171–173 NSPs, see Non-starch polysaccharide O OAC, see Oil absorption capacity Oats, 35, 39, 53 Octenyl succinic anhydride (OSA), 127, 128, 136 Oil absorption capacity (OAC), 28, 29 OSA, see Octenyl succinic anhydride Oxidation, 37, 127, 128, 135 P Pale ale malt, 154 Pale lager malt, 153–154 Pastas, 171–173 Pasting properties, 30 Pasting temperature (PT), 30 Peak viscosity (PV), 30, 107 Pearling, 26, 80–81 PEF, see Pulse electric feld technology Peptide tyrosine (PYY), 72 Pericarp, 8 PGSs, see Pregelatinized starches Phenolic acids, 35, 38–44

18 7

Phenolic compounds, 12–13, 27, 39, 42 Phosphorus, 12 Phosphoryl chloride (POCl3), 137 Physical modifcation, starch, 124–129 nonthermal physical modifcation, 131–134 thermal physical modifcation, 124–131 Physical properties, 21–23 Phytates, 83 Phytosterols, 52–53 Plant lignans, 51 Polyphenol oxidase, 81 Porosity, 23 Power law equation, 110 Pregelatinized starches (PGSs), 124, 127, 129–130 Proanthocyanidin, 46 Processing efect, nutrition and antioxidant properties cooking, 89 dehulling/pearling, 80–81 fermentation, 84–86 germination, 82–84 heat treatment efects, 79–80 methods, 78, 79 milling, 81 roasting, 88–89 thermal treatment, 86–87 Product formulation, 165–169 barley tea, 176 biscuits, 173–175 breads, 166, 169–170 cakes, 175 cookies, 173–175 fatbreads, 170–171 noodles, 171–173 pastas, 171–173 tarhana, 175–176 tortilla, 176

18 8

IN D E X

Propionate, 69 Protein, 10–11 PT, see Pasting temperature Pulse electric feld (PEF) technology, 133–134 Purple barley, 48 PV, see Peak viscosity PYY, see Peptide tyrosine R Rapidly digestible starch (RDS), 113, 114 Rapid visco analyser (RVA), 30, 107 RDS, see Rapidly digestible starch Reactive nitrogen species (RNS), 37 Reactive oxygen species (ROS), 36, 37 RNS, see Reactive nitrogen species ROS, see Reactive oxygen species RVA, see Rapid visco analyser S Scanning electron microscope (SEM), 102, 104, 133, 137 SCFAs, see Short-chain fatty acids SDF, see Soluble dietary fbre SDS, see Slowly digestible starch Seed density, 23 Seed volume, 22 SEM, see Scanning electron microscope Short-chain fatty acids (SCFAs), 69, 71, 72 Slowly digestible starch (SDS), 113, 114 Sodium trimetaphosphate (STMP), 137 Sodium tripolyphosphate (STPP), 137, 138

Soluble dietary fbre (SDF), 9, 65, 66, 83, 88 Sorghum, 176 SP, see Swelling power Sphericity, 22 Spray drying, 129 Starch, 8, 13 applications, 114–115 chemical composition, 100–102 chemical modifcations, 124–129 acetylation, 134–135 acid hydrolysis, 136 cross-linking, 137 dual modifcation, 138–139 octenyl succinic anhydride, 136 oxidation, 135 succinylation, 137–138 chemical structure, 99–100 crystallinity, 106, 107 digestion, 113 enzymatic modifcations, 139–140 fow and dynamic oscillatory analysis, 109–110 granular morphology, 102–105 in vitro digestibility, 113–114 isolation, 97–98 pasting properties, 106–109 physical modifcation, 124–129 nonthermal physical modifcation, 131–134 thermal physical modifcation, 124–131 purifcation, 97–98 solubility, 105–106 swelling power (SP), 105–106 thermal properties, 111–113 Steeping process, 79, 149–150 STMP, see Sodium trimetaphosphate

IN D E X

Storage modulus (Gʹ), 110 STPP, see Sodium tripolyphosphate Succinylation, 127, 129, 137–138 Surface area, 22–23 T Tannins, 48, 51 Tarhana, 168, 175–176 TFC, see Total favonoid content Termal physical modifcation, 124–129 hydrothermal treatment, 130–131 annealing, 130–131 heat-moisture treatment, 131 pregelatinized starches (PGSs), 124, 127, 129–130 Termogram, 30 Tousand kernel weight, 21 Tocopherols, 44, 49–50 Tocotrienols, 45, 50 Tortilla, 171, 176 Total favonoid content (TFC), 46 Total phenolic compound, 87 Transmission electron microscopy, 104 Trough viscosity (TV), 30, 107 True density, 23 TV, see Trough viscosity

18 9

U Ultrasonication, 126, 133 V Vienna malt, 154 Vitamins, 11–12 B1, 12 B2, 12 W Water absorption capacity, 28, 29 Water solubility index (WSI), 105 Wet-milling methods, 97 Wheat, 3, 35, 53 WHO, see World Health Organization Whole-grain cereal bioactive compounds, 39 health benefts of, 36 World Health Organization (WHO), 69 WSI, see Water solubility index X X-ray difraction (XRD), 106, 107