Cereal_grains_for_the_food_and_beverage_industries_2075944_z_lib

Cereal grains for the food
and beverage industries

© Woodhead Publishing Limited, 2013

Related titles:

Cereal grains: Assessing and managing quality (ISBN 978-1-84569-563-7)
Rice quality: A guide to rice properties and analysis (ISBN 978-1-84569-485-2)
Breadmaking: Improving quality (ISBN 978-0-85709-060-7)
Details of these books and a complete list of titles from Woodhead Publishing can
be obtained by:
• visiting our web site at www.woodheadpublishing.com
• contacting Customer Services (e-mail: [email protected]; fax:

+44 (0) 1223 832819; tel.: +44 (0) 1223 499140 ext. 130; address: Woodhead
Publishing Limited, 80 High Street, Sawston, Cambridge CB22 3HJ, UK)
• contacting our US office (e-mail: [email protected]; tel.:
(215) 928 9112; address: Woodhead Publishing, 1518 Walnut Street, Suite 1100,
Philadelphia, PA 19102-3406, USA)
If you would like e-versions of our content, please visit our online platform:
www.woodheadpublishingonline.com. Please recommend it to your librarian so
that everyone in your institution can benefit from the wealth of content on the site.
We are always happy to receive suggestions for new books from potential
editors. To enquire about contributing to our Food Science, Technology and
Nutrition series, please send your name, contact address and details of the topic/s
you are interested in to [email protected]. We look forward
to hearing from you.

The Woodhead team responsible for publishing this book:
Commissioning Editor: Sarah Hughes
Project Editor: Rachel Cox
Editorial and Production Manager: Mary Campbell
Production Editor: Adam Hooper
Copyeditor: Helen McFadyen
Proofreader: George Moore
Cover Designer: Terry Callanan

© Woodhead Publishing Limited, 2013

Woodhead Publishing Series in Food Science, Technology and Nutrition:
Number 248

Cereal grains for the food
and beverage industries

Elke K. Arendt and Emanuele Zannini

Oxford Cambridge Philadelphia New Delhi
© Woodhead Publishing Limited, 2013

Published by Woodhead Publishing Limited,
80 High Street, Sawston, Cambridge CB22 3HJ, UK
www.woodheadpublishing.com
www.woodheadpublishingonline.com

Woodhead Publishing, 1518 Walnut Street, Suite 1100, Philadelphia, PA 19102-3406, USA

Woodhead Publishing India Private Limited, G-2, Vardaan House, 7/28 Ansari Road,
Daryaganj, New Delhi – 110002, India
www.woodheadpublishingindia.com

First published 2013, Woodhead Publishing Limited
© Woodhead Publishing Limited, 2013. The publisher has made every effort to ensure that
permission for copyright material has been obtained by authors wishing to use such
material. The authors and the publisher will be glad to hear from any copyright holder it
has not been possible to contact.
The authors have asserted their moral rights.

This book contains information obtained from authentic and highly regarded sources.
Reprinted material is quoted with permission, and sources are indicated. Reasonable efforts
have been made to publish reliable data and information, but the authors and the publishers
cannot assume responsibility for the validity of all materials. Neither the authors nor the
publishers, nor anyone else associated with this publication, shall be liable for any loss,
damage or liability directly or indirectly caused or alleged to be caused by this book.

Neither this book nor any part may be reproduced or transmitted in any form or by any
means, electronic or mechanical, including photocopying, microfilming and recording, or by
any information storage or retrieval system, without permission in writing from Woodhead
Publishing Limited.

The consent of Woodhead Publishing Limited does not extend to copying for general
distribution, for promotion, for creating new works, or for resale. Specific permission must
be obtained in writing from Woodhead Publishing Limited for such copying.

Trademark notice: Product or corporate names may be trademarks or registered trademarks,
and are used only for identification and explanation, without intent to infringe.

British Library Cataloguing in Publication Data
A catalogue record for this book is available from the British Library.

Library of Congress Control Number: 2013930802

ISBN 978-0-85709-413-1 (print)
ISBN 978-0-85709-892-4 (online)
ISSN 2042-8049 Woodhead Publishing Series in Food Science, Technology and Nutrition (print)
ISSN 2042-8057 Woodhead Publishing Series in Food Science,Technology and Nutrition (online)

The publisher’s policy is to use permanent paper from mills that operate a sustainable
forestry policy, and which has been manufactured from pulp which is processed using
acid-free and elemental chlorine-free practices. Furthermore, the publisher ensures that
the text paper and cover board used have met acceptable environmental accreditation
standards.

Typeset by Toppan Best-set Premedia Limited
Printed by MPG Printgroup, UK

© Woodhead Publishing Limited, 2013

Contents

Author contact details................................................................................. ix
Woodhead Publishing Series in Food Science, Technology
and Nutrition .............................................................................................. xi
Foreword...................................................................................................... xxiii
Preface.......................................................................................................... xxv

1 Wheat and other Triticum grains..................................................... 1
1.1 Introduction............................................................................ 1
1.2 Structure of wheat grain....................................................... 5
1.3 Wheat carbohydrate composition and properties............. 9
1.4 Wheat protein composition and properties ....................... 15
1.5 Other constituents of wheat................................................. 20
1.6 Flour milling........................................................................... 23
1.7 Bakery products based on wheat ........................................ 32
1.8 Durum wheat products......................................................... 42
1.9 Products based on other types of wheat ............................ 47
1.10 Beverages based on wheat ................................................... 50
1.11 Conclusions ............................................................................ 56
1.12 Future trends.......................................................................... 56
1.13 References .............................................................................. 57

2 Maize ................................................................................................... 67
2.1 Introduction............................................................................ 67
2.2 Maize carbohydrate composition and properties ............. 77

© Woodhead Publishing Limited, 2013

vi Contents

2.3 Other constituents of the maize kernel.............................. 81
2.4 Maize processing ................................................................... 87
2.5 Applications of maize in foods............................................ 91
2.6 Applications of maize in beverages .................................... 101
2.7 Conclusions ............................................................................ 103
2.8 Future trends.......................................................................... 103
2.9 References .............................................................................. 104

3 Rice ..................................................................................................... 114
3.1 Introduction............................................................................ 114
3.2 Rice carbohydrate composition and properties ................ 122
3.3 Other constituents of the rice kernel.................................. 125
3.4 Rice processing ...................................................................... 132
3.5 Food and beverage applications of rice.............................. 137
3.6 Conclusions ............................................................................ 145
3.7 Future trends.......................................................................... 145
3.8 References .............................................................................. 146

4 Barley ................................................................................................... 155
4.1 Introduction............................................................................ 155
4.2 Barley carbohydrate composition and properties ............ 165
4.3 Other constituents of the barley kernel ............................. 170
4.4 Barley milling......................................................................... 174
4.5 Applications of barley in foods ........................................... 177
4.6 Applications of barley in beverages ................................... 184
4.7 Conclusions ............................................................................ 190
4.8 Future trends.......................................................................... 190
4.9 References .............................................................................. 191

5 Triticale ................................................................................................ 201
5.1 Introduction............................................................................ 201
5.2 Chemical composition of the triticale kernel .................... 205
5.3 Triticale milling and applications in foods and
beverages ................................................................................ 210
5.4 Conclusions ............................................................................ 215
5.5 Future trends.......................................................................... 215
5.6 References .............................................................................. 216

6 Rye ....................................................................................................... 220
6.1 Introduction............................................................................ 220
6.2 Chemical composition of the rye kernel ............................ 229
6.3 Rye milling and applications in foods and beverages ...... 234
6.4 Conclusions ............................................................................ 237
6.5 Future trends.......................................................................... 238
6.6 References .............................................................................. 238

© Woodhead Publishing Limited, 2013

Contents vii

7 Oats ...................................................................................................... 243
7.1 Introduction............................................................................ 243
7.2 Oat carbohydrate composition and properties ................. 253
7.3 Other constituents of the oat kernel .................................. 259
7.4 Oat milling.............................................................................. 266
7.5 Food and beverage applications of oats............................. 269
7.6 Conclusions ............................................................................ 273
7.7 Future trends.......................................................................... 273
7.8 References .............................................................................. 274

8 Sorghum............................................................................................... 283
8.1 Introduction............................................................................ 283
8.2 Chemical constituents of the sorghum kernel................... 292
8.3 Sorghum milling..................................................................... 299
8.4 Applications in foods and beverages.................................. 299
8.5 Conclusions ............................................................................ 304
8.6 Future trends.......................................................................... 305
8.7 References .............................................................................. 305

9 Millet ................................................................................................... 312
9.1 Introduction............................................................................ 312
9.2 Proso millet carbohydrate composition
and properties ........................................................................ 318
9.3 Proso millet protein composition and properties ............. 322
9.4 Other constituents of proso millet ...................................... 329
9.5 Processing of proso millet .................................................... 335
9.6 Food and beverage applications of proso millet ............... 339
9.7 Future trends.......................................................................... 342
9.8 References .............................................................................. 343

10 Teff........................................................................................................ 351
10.1 Introduction............................................................................ 351
10.2 Chemical composition of the teff kernel............................ 356
10.3 Teff milling and applications in foods
and beverages ....................................................................... 361
10.4 Conclusions ............................................................................ 365
10.5 Future trends.......................................................................... 365
10.6 References .............................................................................. 365

11 Buckwheat ........................................................................................... 369
11.1 Introduction............................................................................ 369
11.2 Buckwheat carbohydrate composition
and properties ........................................................................ 373
11.3 Buckwheat protein composition and properties ............... 379
11.4 Other constituents of buckwheat ....................................... 386

© Woodhead Publishing Limited, 2013

viii Contents
11.5 Food and beverage applications of buckwheat ................ 392
11.6 Conclusions ............................................................................ 400
11.7 Future trends.......................................................................... 401
11.8 References .............................................................................. 401

12 Quinoa ................................................................................................. 409
12.1 Introduction............................................................................ 409
12.2 Chemical composition of quinoa seed................................ 417
12.3 Quinoa milling and applications in foods
and beverages......................................................................... 425
12.4 Conclusions ............................................................................ 432
12.5 Future trends.......................................................................... 432
12.6 References .............................................................................. 433

13 Amaranth............................................................................................. 439
13.1 Introduction............................................................................ 439
13.2 Amaranth carbohydrate composition and properties ...... 444
13.3 Other constituents of amaranth ......................................... 450
13.4 Amaranth processing and applications in foods
and beverages ....................................................................... 460
13.5 Conclusions ............................................................................ 466
13.6 Future trends.......................................................................... 466
13.7 References .............................................................................. 466

Index............................................................................................................. 475

© Woodhead Publishing Limited, 2013

Author contact details

Professor Elke Arendt and Dr Emanuele Zannini
School of Food and Nutritional Sciences
University College Cork
Western Road
Ireland
E-mail: [email protected]; [email protected]

© Woodhead Publishing Limited, 2013



Woodhead Publishing Series in Food
Science, Technology and Nutrition

1 Chilled foods: a comprehensive guide Edited by C. Dennis and
M. Stringer

2 Yoghurt: science and technology A. Y. Tamime and R. K. Robinson
3 Food processing technology: principles and practice P. J. Fellows
4 Bender’s dictionary of nutrition and food technology Sixth edition

D. A. Bender
5 Determination of veterinary residues in food Edited by N. T. Crosby
6 Food contaminants: sources and surveillance Edited by C. Creaser

and R. Purchase
7 Nitrates and nitrites in food and water Edited by M. J. Hill
8 Pesticide chemistry and bioscience: the food-environment challenge

Edited by G. T. Brooks and T. Roberts
9 Pesticides: developments, impacts and controls Edited by G. A. Best

and A. D. Ruthven
10 Dietary fibre: chemical and biological aspects Edited by

D. A. T. Southgate, K. W. Waldron, I. T. Johnson and G. R. Fenwick
11 Vitamins and minerals in health and nutrition M. Tolonen
12 Technology of biscuits, crackers and cookies Second edition

D. Manley
13 Instrumentation and sensors for the food industry Edited by

E. Kress-Rogers
14 Food and cancer prevention: chemical and biological aspects Edited

by K. W. Waldron, I. T. Johnson and G. R. Fenwick
15 Food colloids: proteins, lipids and polysaccharides Edited by

E. Dickinson and B. Bergenstahl

© Woodhead Publishing Limited, 2013

xii Woodhead Publishing Series in Food Science, Technology and Nutrition

16 Food emulsions and foams Edited by E. Dickinson
17 Maillard reactions in chemistry, food and health Edited by

T. P. Labuza, V. Monnier, J. Baynes and J. O’Brien
18 The Maillard reaction in foods and medicine Edited by J. O’Brien,

H. E. Nursten, M. J. Crabbe and J. M. Ames
19 Encapsulation and controlled release Edited by D. R. Karsa and

R. A. Stephenson
20 Flavours and fragrances Edited by A. D. Swift
21 Feta and related cheeses Edited by A. Y. Tamime and R. K. Robinson
22 Biochemistry of milk products Edited by A. T. Andrews and

J. R. Varley
23 Physical properties of foods and food processing systems M. J. Lewis
24 Food irradiation: a reference guide V. M. Wilkinson and G. Gould
25 Kent’s technology of cereals: an introduction for students of food

science and agriculture Fourth edition N. L. Kent and A. D. Evers
26 Biosensors for food analysis Edited by A. O. Scott
27 Separation processes in the food and biotechnology industries:

principles and applications Edited by A. S. Grandison and
M. J. Lewis
28 Handbook of indices of food quality and authenticity R. S. Singhal,
P. K. Kulkarni and D. V. Rege
29 Principles and practices for the safe processing of foods
D. A. Shapton and N. F. Shapton
30 Biscuit, cookie and cracker manufacturing manuals Volume 1:
ingredients D. Manley
31 Biscuit, cookie and cracker manufacturing manuals Volume 2: biscuit
doughs D. Manley
32 Biscuit, cookie and cracker manufacturing manuals Volume 3: biscuit
dough piece forming D. Manley
33 Biscuit, cookie and cracker manufacturing manuals Volume 4:
baking and cooling of biscuits D. Manley
34 Biscuit, cookie and cracker manufacturing manuals Volume 5:
secondary processing in biscuit manufacturing D. Manley
35 Biscuit, cookie and cracker manufacturing manuals Volume 6: biscuit
packaging and storage D. Manley
36 Practical dehydration Second edition M. Greensmith
37 Lawrie’s meat science Sixth edition R. A. Lawrie
38 Yoghurt: science and technology Second edition A. Y. Tamime and
R. K. Robinson
39 New ingredients in food processing: biochemistry and agriculture
G. Linden and D. Lorient
40 Benders’ dictionary of nutrition and food technology Seventh
edition D. A. Bender and A. E. Bender
41 Technology of biscuits, crackers and cookies Third edition
D. Manley

© Woodhead Publishing Limited, 2013

Woodhead Publishing Series in Food Science, Technology and Nutrition xiii

42 Food processing technology: principles and practice Second edition
P. J. Fellows

43 Managing frozen foods Edited by C. J. Kennedy
44 Handbook of hydrocolloids Edited by G. O. Phillips and

P. A. Williams
45 Food labelling Edited by J. R. Blanchfield
46 Cereal biotechnology Edited by P. C. Morris and J. H. Bryce
47 Food intolerance and the food industry Edited by T. Dean
48 The stability and shelf-life of food Edited by D. Kilcast and

P. Subramaniam
49 Functional foods: concept to product Edited by G. R. Gibson and

C. M. Williams
50 Chilled foods: a comprehensive guide Second edition Edited by

M. Stringer and C. Dennis
51 HACCP in the meat industry Edited by M. Brown
52 Biscuit, cracker and cookie recipes for the food industry D. Manley
53 Cereals processing technology Edited by G. Owens
54 Baking problems solved S. P. Cauvain and L. S. Young
55 Thermal technologies in food processing Edited by P. Richardson
56 Frying: improving quality Edited by J. B. Rossell
57 Food chemical safety Volume 1: contaminants Edited by D. Watson
58 Making the most of HACCP: learning from others’ experience

Edited by T. Mayes and S. Mortimore
59 Food process modelling Edited by L. M. M. Tijskens,

M. L. A. T. M. Hertog and B. M. Nicolaï
60 EU food law: a practical guide Edited by K. Goodburn
61 Extrusion cooking: technologies and applications Edited by

R. Guy
62 Auditing in the food industry: from safety and quality to

environmental and other audits Edited by M. Dillon and C. Griffith
63 Handbook of herbs and spices Volume 1 Edited by K. V. Peter
64 Food product development: maximising success M. Earle, R. Earle

and A. Anderson
65 Instrumentation and sensors for the food industry Second edition

Edited by E. Kress-Rogers and C. J. B. Brimelow
66 Food chemical safety Volume 2: additives Edited by D. Watson
67 Fruit and vegetable biotechnology Edited by V. Valpuesta
68 Foodborne pathogens: hazards, risk analysis and control Edited by

C. de W. Blackburn and P. J. McClure
69 Meat refrigeration S. J. James and C. James
70 Lockhart and Wiseman’s crop husbandry Eighth edition

H. J. S. Finch, A. M. Samuel and G. P. F. Lane
71 Safety and quality issues in fish processing Edited by H. A. Bremner
72 Minimal processing technologies in the food industries Edited by

T. Ohlsson and N. Bengtsson

© Woodhead Publishing Limited, 2013

xiv Woodhead Publishing Series in Food Science, Technology and Nutrition

73 Fruit and vegetable processing: improving quality Edited by
W. Jongen

74 The nutrition handbook for food processors Edited by C. J. K. Henry
and C. Chapman

75 Colour in food: improving quality Edited by D. MacDougall
76 Meat processing: improving quality Edited by J. P. Kerry, J. F. Kerry

and D. A. Ledward
77 Microbiological risk assessment in food processing Edited by

M. Brown and M. Stringer
78 Performance functional foods Edited by D. Watson
79 Functional dairy products Volume 1 Edited by T. Mattila-Sandholm

and M. Saarela
80 Taints and off-flavours in foods Edited by B. Baigrie
81 Yeasts in food Edited by T. Boekhout and V. Robert
82 Phytochemical functional foods Edited by I. T. Johnson and

G. Williamson
83 Novel food packaging techniques Edited by R. Ahvenainen
84 Detecting pathogens in food Edited by T. A. McMeekin
85 Natural antimicrobials for the minimal processing of foods Edited by

S. Roller
86 Texture in food Volume 1: semi-solid foods Edited by

B. M. McKenna
87 Dairy processing: improving quality Edited by G. Smit
88 Hygiene in food processing: principles and practice Edited by

H. L. M. Lelieveld, M. A. Mostert, B. White and J. Holah
89 Rapid and on-line instrumentation for food quality assurance

Edited by I. Tothill
90 Sausage manufacture: principles and practice E. Essien
91 Environmentally-friendly food processing Edited by B. Mattsson and

U. Sonesson
92 Bread making: improving quality Edited by S. P. Cauvain
93 Food preservation techniques Edited by P. Zeuthen and

L. Bøgh-Sørensen
94 Food authenticity and traceability Edited by M. Lees
95 Analytical methods for food additives R. Wood, L. Foster, A. Damant

and P. Key
96 Handbook of herbs and spices Volume 2 Edited by K. V. Peter
97 Texture in food Volume 2: solid foods Edited by D. Kilcast
98 Proteins in food processing Edited by R. Yada
99 Detecting foreign bodies in food Edited by M. Edwards
100 Understanding and measuring the shelf-life of food Edited by

R. Steele
101 Poultry meat processing and quality Edited by G. Mead
102 Functional foods, ageing and degenerative disease Edited by

C. Remacle and B. Reusens

© Woodhead Publishing Limited, 2013

Woodhead Publishing Series in Food Science, Technology and Nutrition xv

103 Mycotoxins in food: detection and control Edited by N. Magan and
M. Olsen

104 Improving the thermal processing of foods Edited by P. Richardson
105 Pesticide, veterinary and other residues in food Edited by D. Watson
106 Starch in food: structure, functions and applications Edited by

A.-C. Eliasson
107 Functional foods, cardiovascular disease and diabetes Edited by

A. Arnoldi
108 Brewing: science and practice D. E. Briggs, P. A. Brookes, R. Stevens

and C. A. Boulton
109 Using cereal science and technology for the benefit of consumers:

proceedings of the 12th International ICC Cereal and Bread
Congress, 24 – 26th May, 2004, Harrogate, UK Edited by
S. P. Cauvain, L. S. Young and S. Salmon
110 Improving the safety of fresh meat Edited by J. Sofos
111 Understanding pathogen behaviour: virulence, stress response and
resistance Edited by M. Griffiths
112 The microwave processing of foods Edited by H. Schubert and
M. Regier
113 Food safety control in the poultry industry Edited by G. Mead
114 Improving the safety of fresh fruit and vegetables Edited by
W. Jongen
115 Food, diet and obesity Edited by D. Mela
116 Handbook of hygiene control in the food industry Edited by
H. L. M. Lelieveld, M. A. Mostert and J. Holah
117 Detecting allergens in food Edited by S. Koppelman and S. Hefle
118 Improving the fat content of foods Edited by C. Williams and
J. Buttriss
119 Improving traceability in food processing and distribution Edited by
I. Smith and A. Furness
120 Flavour in food Edited by A. Voilley and P. Etievant
121 The Chorleywood bread process S. P. Cauvain and L. S. Young
122 Food spoilage microorganisms Edited by C. de W. Blackburn
123 Emerging foodborne pathogens Edited by Y. Motarjemi and
M. Adams
124 Benders’ dictionary of nutrition and food technology Eighth edition
D. A. Bender
125 Optimising sweet taste in foods Edited by W. J. Spillane
126 Brewing: new technologies Edited by C. Bamforth
127 Handbook of herbs and spices Volume 3 Edited by K. V. Peter
128 Lawrie’s meat science Seventh edition R. A. Lawrie in collaboration
with D. A. Ledward
129 Modifying lipids for use in food Edited by F. Gunstone
130 Meat products handbook: practical science and technology
G. Feiner

© Woodhead Publishing Limited, 2013

xvi Woodhead Publishing Series in Food Science, Technology and Nutrition

131 Food consumption and disease risk: consumer-pathogen interactions
Edited by M. Potter

132 Acrylamide and other hazardous compounds in heat-treated foods
Edited by K. Skog and J. Alexander

133 Managing allergens in food Edited by C. Mills, H. Wichers and
K. Hoffman-Sommergruber

134 Microbiological analysis of red meat, poultry and eggs Edited by
G. Mead

135 Maximising the value of marine by-products Edited by F. Shahidi
136 Chemical migration and food contact materials Edited by K. Barnes,

R. Sinclair and D. Watson
137 Understanding consumers of food products Edited by L. Frewer and

H. van Trijp
138 Reducing salt in foods: practical strategies Edited by D. Kilcast and

F. Angus
139 Modelling microorganisms in food Edited by S. Brul, S. Van Gerwen

and M. Zwietering
140 Tamime and Robinson’s Yoghurt: science and technology Third

edition A. Y. Tamime and R. K. Robinson
141 Handbook of waste management and co-product recovery in food

processing Volume 1 Edited by K. W. Waldron
142 Improving the flavour of cheese Edited by B. Weimer
143 Novel food ingredients for weight control Edited by C. J. K. Henry
144 Consumer-led food product development Edited by H. MacFie
145 Functional dairy products Volume 2 Edited by M. Saarela
146 Modifying flavour in food Edited by A. J. Taylor and J. Hort
147 Cheese problems solved Edited by P. L. H. McSweeney
148 Handbook of organic food safety and quality Edited by J. Cooper,

C. Leifert and U. Niggli
149 Understanding and controlling the microstructure of complex foods

Edited by D. J. McClements
150 Novel enzyme technology for food applications Edited by R. Rastall
151 Food preservation by pulsed electric fields: from research to

application Edited by H. L. M. Lelieveld and S. W. H. de Haan
152 Technology of functional cereal products Edited by B. R. Hamaker
153 Case studies in food product development Edited by M. Earle and

R. Earle
154 Delivery and controlled release of bioactives in foods and

nutraceuticals Edited by N. Garti
155 Fruit and vegetable flavour: recent advances and future prospects

Edited by B. Brückner and S. G. Wyllie
156 Food fortification and supplementation: technological, safety and

regulatory aspects Edited by P. Berry Ottaway
157 Improving the health-promoting properties of fruit and vegetable

products Edited by F. A. Tomás-Barberán and M. I. Gil

© Woodhead Publishing Limited, 2013

Woodhead Publishing Series in Food Science, Technology and Nutrition xvii

158 Improving seafood products for the consumer Edited by T. Børresen
159 In-pack processed foods: improving quality Edited by P. Richardson
160 Handbook of water and energy management in food processing

Edited by J. Klemeš, R. Smith and J.-K. Kim
161 Environmentally compatible food packaging Edited by E. Chiellini
162 Improving farmed fish quality and safety Edited by Ø. Lie
163 Carbohydrate-active enzymes Edited by K.-H. Park
164 Chilled foods: a comprehensive guide Third edition Edited by

M. Brown
165 Food for the ageing population Edited by M. M. Raats,

C. P. G. M. de Groot and W. A. Van Staveren
166 Improving the sensory and nutritional quality of fresh meat

Edited by J. P. Kerry and D. A. Ledward
167 Shellfish safety and quality Edited by S. E. Shumway and

G. E. Rodrick
168 Functional and speciality beverage technology Edited by P. Paquin
169 Functional foods: principles and technology M. Guo
170 Endocrine-disrupting chemicals in food Edited by I. Shaw
171 Meals in science and practice: interdisciplinary research and business

applications Edited by H. L. Meiselman
172 Food constituents and oral health: current status and future

prospects Edited by M. Wilson
173 Handbook of hydrocolloids Second edition Edited by G. O. Phillips

and P. A. Williams
174 Food processing technology: principles and practice Third edition

P. J. Fellows
175 Science and technology of enrobed and filled chocolate,

confectionery and bakery products Edited by G. Talbot
176 Foodborne pathogens: hazards, risk analysis and control Second

edition Edited by C. de W. Blackburn and P. J. McClure
177 Designing functional foods: measuring and controlling food

structure breakdown and absorption Edited by D. J. McClements and
E. A. Decker
178 New technologies in aquaculture: improving production efficiency,
quality and environmental management Edited by G. Burnell and
G. Allan
179 More baking problems solved S. P. Cauvain and L. S. Young
180 Soft drink and fruit juice problems solved P. Ashurst and R. Hargitt
181 Biofilms in the food and beverage industries Edited by
P. M. Fratamico, B. A. Annous and N. W. Gunther
182 Dairy-derived ingredients: food and neutraceutical uses Edited by
M. Corredig
183 Handbook of waste management and co-product recovery in food
processing Volume 2 Edited by K. W. Waldron
184 Innovations in food labelling Edited by J. Albert

© Woodhead Publishing Limited, 2013

xviii Woodhead Publishing Series in Food Science, Technology and Nutrition

185 Delivering performance in food supply chains Edited by C. Mena
and G. Stevens

186 Chemical deterioration and physical instability of food and
beverages Edited by L. H. Skibsted, J. Risbo and M. L. Andersen

187 Managing wine quality Volume 1: viticulture and wine quality Edited
by A. G. Reynolds

188 Improving the safety and quality of milk Volume 1: milk production
and processing Edited by M. Griffiths

189 Improving the safety and quality of milk Volume 2: improving
quality in milk products Edited by M. Griffiths

190 Cereal grains: assessing and managing quality Edited by C. Wrigley
and I. Batey

191 Sensory analysis for food and beverage quality control: a practical
guide Edited by D. Kilcast

192 Managing wine quality Volume 2: oenology and wine quality Edited
by A. G. Reynolds

193 Winemaking problems solved Edited by C. E. Butzke
194 Environmental assessment and management in the food industry

Edited by U. Sonesson, J. Berlin and F. Ziegler
195 Consumer-driven innovation in food and personal care products

Edited by S. R. Jaeger and H. MacFie
196 Tracing pathogens in the food chain Edited by S. Brul,

P. M. Fratamico and T. A. McMeekin
197 Case studies in novel food processing technologies: innovations in

processing, packaging, and predictive modelling Edited by
C. J. Doona, K. Kustin and F. E. Feeherry
198 Freeze-drying of pharmaceutical and food products T.-C. Hua,
B.-L. Liu and H. Zhang
199 Oxidation in foods and beverages and antioxidant applications
Volume 1: understanding mechanisms of oxidation and
antioxidant activity Edited by E. A. Decker, R. J. Elias and
D. J. McClements
200 Oxidation in foods and beverages and antioxidant applications
Volume 2: management in different industry sectors Edited by
E. A. Decker, R. J. Elias and D. J. McClements
201 Protective cultures, antimicrobial metabolites and bacteriophages
for food and beverage biopreservation Edited by C. Lacroix
202 Separation, extraction and concentration processes in the food,
beverage and nutraceutical industries Edited by S. S. H. Rizvi
203 Determining mycotoxins and mycotoxigenic fungi in food and feed
Edited by S. De Saeger
204 Developing children’s food products Edited by D. Kilcast and
F. Angus
205 Functional foods: concept to product Second edition Edited by
M. Saarela

© Woodhead Publishing Limited, 2013

Woodhead Publishing Series in Food Science, Technology and Nutrition xix

206 Postharvest biology and technology of tropical and subtropical fruits
Volume 1: fundamental issues Edited by E. M. Yahia

207 Postharvest biology and technology of tropical and subtropical fruits
Volume 2: açai to citrus Edited by E. M. Yahia

208 Postharvest biology and technology of tropical and subtropical fruits
Volume 3: cocona to mango Edited by E. M. Yahia

209 Postharvest biology and technology of tropical and subtropical
fruits Volume 4: mangosteen to white sapote Edited by
E. M. Yahia

210 Food and beverage stability and shelf life Edited by D. Kilcast and
P. Subramaniam

211 Processed Meats: improving safety, nutrition and quality Edited by
J. P. Kerry and J. F. Kerry

212 Food chain integrity: a holistic approach to food traceability, safety,
quality and authenticity Edited by J. Hoorfar, K. Jordan, F. Butler
and R. Prugger

213 Improving the safety and quality of eggs and egg products Volume 1
Edited by Y. Nys, M. Bain and F. Van Immerseel

214 Improving the safety and quality of eggs and egg products Volume 2
Edited by F. Van Immerseel, Y. Nys and M. Bain

215 Animal feed contamination: effects on livestock and food safety
Edited by J. Fink-Gremmels

216 Hygienic design of food factories Edited by J. Holah and
H. L. M. Lelieveld

217 Manley’s technology of biscuits, crackers and cookies Fourth edition
Edited by D. Manley

218 Nanotechnology in the food, beverage and nutraceutical industries
Edited by Q. Huang

219 Rice quality: a guide to rice properties and analysis
K. R. Bhattacharya

220 Advances in meat, poultry and seafood packaging Edited by
J. P. Kerry

221 Reducing saturated fats in foods Edited by G. Talbot
222 Handbook of food proteins Edited by G. O. Phillips and

P. A. Williams
223 Lifetime nutritional influences on cognition, behaviour and

psychiatric illness Edited by D. Benton
224 Food machinery for the production of cereal foods, snack foods and

confectionery L.-M. Cheng
225 Alcoholic beverages: sensory evaluation and consumer research

Edited by J. Piggott
226 Extrusion problems solved: food, pet food and feed M. N. Riaz and

G. J. Rokey
227 Handbook of herbs and spices Second edition Volume 1 Edited by

K. V. Peter

© Woodhead Publishing Limited, 2013

xx Woodhead Publishing Series in Food Science, Technology and Nutrition

228 Handbook of herbs and spices Second edition Volume 2 Edited by
K. V. Peter

229 Breadmaking: improving quality Second edition Edited by
S. P. Cauvain

230 Emerging food packaging technologies: principles and practice
Edited by K. L. Yam and D. S. Lee

231 Infectious disease in aquaculture: prevention and control Edited by
B. Austin

232 Diet, immunity and inflammation Edited by P. C. Calder and
P. Yaqoob

233 Natural food additives, ingredients and flavourings Edited by
D. Baines and R. Seal

234 Microbial decontamination in the food industry: novel methods and
applications Edited by A. Demirci and M. O. Ngadi

235 Chemical contaminants and residues in foods Edited by D. Schrenk
236 Robotics and automation in the food industry: current and future

technologies Edited by D. G. Caldwell
237 Fibre-rich and wholegrain foods: improving quality Edited by

J. A. Delcour and K. Poutanen
238 Computer vision technology in the food and beverage industries

Edited by D.-W. Sun
239 Encapsulation technologies and delivery systems for food

ingredients and nutraceuticals Edited by N. Garti and
D. J. McClements
240 Case studies in food safety and authenticity Edited by J. Hoorfar
241 Heat treatment for insect control: developments and applications
D. Hammond
242 Advances in aquaculture hatchery technology Edited by G. Allan
and G. Burnell
243 Open innovation in the food and beverage industry Edited by
M. Garcia Martinez
244 Trends in packaging of food, beverages and other fast-moving
consumer goods (FMCG) Edited by Neil Farmer
245 New analytical approaches for verifying the origin of food Edited by
P. Brereton
246 Microbial production of food ingredients, enzymes and
nutraceuticals Edited by B. McNeil, D. Archer, I. Giavasis and
L. Harvey
247 Persistent organic pollutants and toxic metals in foods Edited by
M. Rose and A. Fernandes
248 Cereal grains for the food and beverage industries E. Arendt and
E. Zannini
249 Viruses in food and water: risks, surveillance and control Edited by
N. Cook
250 Improving the safety and quality of nuts Edited by L. J. Harris

© Woodhead Publishing Limited, 2013

Woodhead Publishing Series in Food Science, Technology and Nutrition xxi
251 Metabolomics in food and nutrition Edited by B. Weimer and
C. Slupsky
252 Food enrichment with omega-3 fatty acids Edited by C. Jacobsen,
N. Skall Nielsen, A. Frisenfeldt Horn and A.-D. Moltke Sørensen
253 Instrumental assessment of food sensory quality: a practical guide
Edited by D. Kilcast
254 Food microstructures: microscopy, measurement and modelling
Edited by V. J. Morris and K. Groves
255 Handbook of food powders: processes and properties Edited by
B. R. Bhandari, N. Bansal, M. Zhang and P. Schuck
256 Functional ingredients from algae for foods and nutraceuticals
Edited by H. Domínguez
257 Satiation, satiety and the control of food intake: theory and practice
Edited by J. E. Blundell and F. Bellisle
258 Hygiene in food processing: principles and practice Second edition
Edited by H. L. M. Lelieveld, J. Holah and D. Napper
259 Advances in microbial food safety Volume 1 Edited by J. Sofos
260 Global safety of fresh produce: a handbook of best practice,
innovative commercial solutions and case studies Edited by
Jeffrey Hoorfar

© Woodhead Publishing Limited, 2013



Foreword

I set my mind to wondering about how my life would be without cereals or
pseudo-cereals. And I concluded that it would be pretty nigh impossible,
either from a practical survival, functional or life-worth-living perspective.

The day was approaching its conclusion and I was mellowing in my
corner whilst sipping a Scotch. It had been a long one (day that is, not the
whisky), starting with a breakfast of porridge oats and a slice of wheat toast.
In the brewery, my assistant was experimenting with a beer recipe for folks
with coeliac disease, the principle grist components being buckwheat. We
had tasted some others, especially the most common ones founded on
sorghum and millet, but we thought we could do better.

All this cogitation certainly sparked an appetite, sated by a soup and
sandwich lunch with a visitor. Neat restaurant, very bohemian but charming
and the Creamy Cannellini Bean and Amaranth Soup with half Reuben
was delicious. As was the beer!

Somehow, though, at the working day’s end I had worked up sufficient
appetite to look forward to a hearty supper. My good lady has me on a
health kick – making for my projection outside to cook some corn on the
grill while she cobbled together something vegetarian including quinoa
and some flatbread that I hadn’t seen before. ‘Made with teff flour – it’s
Ethiopian,’ I was told. For pudding there was some portion-controlled
rice pudding, but strictly no jam. I confess that, being a carnivore, I missed
my meat.

It was a pleasant evening, so off for a stroll – and I admit to smuggling
one of those nutritious health-food bars with me. Packed with goodness –
and laden with who-knows-what fabulous fibre from cereals inclusive of
triticale.

© Woodhead Publishing Limited, 2013

xxiv Foreword
A little artistic license here? Of course there is. But I think the point is

made, that cereals and pseudo-cereals are at the heart of pretty much any
lifestyle. Civilization as we know it commenced in the Fertile Crescent 8000
years ago (or longer) when a nomadic lifestyle was exchanged for a static
existence involving the cultivation and processing of grain into breads and
beers. It would be somewhat impossible to conceive of a world in which
cereals and their derived products were not at the heart, either as source
of food, directly for the human or for the animals that we farm, or for other
purposes, notably the furnishing of fibre and fuel. In this book, my friend
Elke Arendt and her colleague Emanuele Zannini have delivered a timely
and compelling summary of the major cereals and pseudo-cereals, a volume
that will prove invaluable to scientists and technologists and users of this
diverse array of agricultural staples.

Charles W Bamforth, PhD, D.Sc
Professor

Department of Food Science and Technology
University of California, Davis

© Woodhead Publishing Limited, 2013

Preface

This book represents a comprehensive collection of material relating to
cereal grains, ranging from the economic impact of the grains to their food
and beverage products, whilst also providing an in-depth investigation of
grain morphology, grain constituents and food processing.

Through use of a comprehensive review process, every effort has been
made by the authors to ensure that the Cereal grains for the Food and
Beverages Industries book covers this wide array of topics and is accurate,
readable, and best represents currently known data. The work is also exten-
sively cross-referenced and indexed to ensure that the reader is easily able
to locate information as needed.

This book will be a useful resource for ingredient manufacturers, cereal
scientists, food technologists, marketing personnel, nutritionists, food chem-
ists, policy-makers and health care professionals, as well as those interested
in grain sciences and working in the food and beverage industries.This book
should also be relevant to Food Science departments in Research Institutes
and teaching Universities to aid with academic training and scientific explo-
ration of cereal science and technology.

We would like to thank our research team at the School of Food and
Nutritional Sciences, UCC, Cork for their support, in particular Dr Deborah
M. Waters, for her encouragement and helpful suggestions throughout the
preparation of the book and additionally for offering valuable criticism
during the proofing process. We wish to thank Dr Giulia Cinti who has sup-
plied hand drawn images, and also the authors, editors and publishers who
have allowed reproduction of some of the illustrations and tables included
in the book.

© Woodhead Publishing Limited, 2013

xxvi Preface
Finally, we would also like to thank the editorial and production team at

Woodhead Publishing for their time, effort, advice and expertise. We hope
that this book will be enjoyed, and that it will serve as a long-term source
of knowledge and enlightenment for the reader.

Elke K. Arendt
Emanuele Zannini

© Woodhead Publishing Limited, 2013

1

Wheat and other Triticum grains

DOI: 10.1533/9780857098924.1

Abstract: Wheat is an annual grass belonging to the Poaceae (Gramineae) family,
and represents one of the world’s most important field crops. In contrast to the
other cereal grains, wheat possess the unique gluten proteins capable of forming
the fully visco-elastic dough required to produce pasta, noodles and leavened
baked products, especially bread. Additionally, wheat and wheat derivatives such
as wheat malt, flour and starch are commonly used as adjuncts in the brewing
industry. Wheat also provides essential amino acids, vitamins, minerals, beneficial
phytochemicals and dietary fibre components to the human diet, particularly
when whole-grain products are consumed. Despite their important role in the
human diet, wheat-based foods present health problems for a minority of
people due in particular to wheat intolerance and allergy as coeliac disease and
baker’s asthma, respectively. To meet the predicted future demand for wheat,
improvements in wheat productivity through an efficient wheat breeding plan and
crop management innovations are required.

Key words: wheat, chemical composition, wheat utilization in food and
beverages.

1.1 Introduction

Wheat is one of the major grains in the diet of a vast proportion of the
world’s population. It has therefore a great impact on the nutritional quality
of the meals consumed by a large number of people and consequently on
their health. Although wheat’s ability to produce high yields under a wide
range of conditions is one reason for its popularity compared to other
cereals, the most important factor is the capability of wheat gluten proteins
to form a visco-elastic dough, which is required to bake leavened bread in
particular. These gluten proteins are necessary for the production of the
great variety of foods associated with wheat around the world. This unique
property is the reason why in 2009 the total world harvest was about 680
million tonnes (metric tons, t) with cultivation extending to all continents
except Antarctica and reaching about 217 million hectares (world harvest
area expressed in hectare) (FAO/UN, 2012). During the last 40 years, wheat

© Woodhead Publishing Limited, 2013

2 Cereal grains for the food and beverage industries

productivity has risen steadily, moving from 1.49 tonnes/ha in 1970 to
3 tonnes/ha in 2010, through the availability of better varieties, agriculture
practices and markets and management (Dixon, 2007).

The key characteristic which has given wheat an advantage over other
temperate crops is the unique properties of wheat dough that allow it to be
processed into a range of foodstuffs (Quail, 1996). These properties depend
on the structures and interactions of the grain storage proteins, which
together form the ‘gluten’ protein fraction. Items of confectionery and
snack bars can contain a high proportion of wheat, although its presence
may not be obvious to the consumer. Whole-wheat is also an important
ingredient in breakfast cereals in their many different forms (Fast and
Caldwell, 2000). Further forms of wheat-based foods are burghul (bulgur)
and couscous, for which complete milling of the grain is not required, as
pearled or kibbled wheat is used instead. In the case of burghul, fragmented
wheat is parboiled or steamed and is used in dishes likes tabbouleh, kofta
and kibbeh (Bayram, 2000).

1.1.1 History, production, price, yield and area
The genus Triticum (wheat) originated in the area that stretches from Syria
to Kashmir, and southwards to Ethiopia. In the very distant past, wheats
gradually evolved in this region from wild plants. Since the early 1900s, it
has been known that the wheat species and indeed all members of the
Triticeae tribe have a basic chromosome number of n = 7.

T. aestivum probably generated spontaneously somewhere in the Iranian
highlands or nearby areas. Archaeological finds indicate that this took place
some 6000 years BC (Belderok, 2000). The unique milling and baking prop-
erties of common bread wheat are not found among the diploid and tetra-
ploid wheats. The desirable quality characteristics of bread wheats have
been attributed preponderantly to the presence of the D genome compo-
nent (Belderok, 2000; Tonk et al., 2010). The first evidence for wheat utiliza-
tion comes from the Ohalo II site on the shore of the Sea of Galilee, Israel,
where barley (Hordeum vulgare) and brittle, wild tetraploid wild emmer
wheat (Triticum dicoccum), dated as 19 000 years old, were found, suggest-
ing the initial steps towards settled and cereal agriculture (Kislev et al.,
1992). Wheat and barley were among the earliest domesticated crop plants,
domestication taking place 10 000 years ago in the Pre-pottery Neolithic
Near East (Lev-Yadun et al., 2000). The accumulation of surplus food sup-
plies enabled large settlements to be established, resulting in the emergence
of Western civilization. The earliest cultivated forms of wheat were essen-
tially landraces selected by farmers from wild populations because of their
superior yield and other characteristics. However, domestication was also
associated with the selection of genetic traits that separated them from their
wild relatives. Two of the most important traits pursued during the domes-
tication were loss of shattering of the spike at maturity, which results in seed

© Woodhead Publishing Limited, 2013

Wheat and other Triticum grains 3

Table 1.1 Wheat and total cereal grain production and producer price in the world
from 2000–2010

Year Total wheat Total cereal Wheat Area Wheat Producer
production as % wheat yield price (US
(Mt) production of total harvested (t/ha) $/tonnes)
(Mt)a grains (Mha)

2000 585.7 2044 28.7 215.4 2.7 179.7
2001 589.8 2093 28.2 214.6 2.7 177.2
2002 574.7 2077 27.7 213.8 2.7 167.4
2003 560.1 2260 24.8 207.7 2.7 190.6
2004 632.7 2247 28.2 216.9 2.9 200.6
2005 626.9 2219 28.3 219.7 2.8 197.1
2006 602.9 2335 25.8 211.2 2.8 205.2
2007 612.6 2503 24.5 216.7 2.8 268.6
2008 683.2 2470 27.7 222.8 3.0 341.8
2009 689.6 2472 27.9 224.6 3.0 266.2
2010 653.7 2412 27.1 217.2 3.0 283.3
Average 619.3 2285 27.1 216.4 2.8 225.2

aTotal cereal production includes corn, rice, wheat, barley, sorghum, millet, oat, rye, mixed
grain.
Source: Data from FAO/UN (2012).

loss at harvesting, and presence of kernels in the free-threshing (naked)
form (Shewry, 2009). In 2010, the production of wheat approached that of
rice (Table 1.1) with 653.7 × 106 t (FAO/UN, 2012) produced worldwide.
Depending on the climate, soil condition, variety, agricultural practices and
other conditions, wheat yields can range from 2.7 to 3.0 tonnes/ha (FAO/
UN, 2012). Nowadays, wheat yields worldwide tend to be higher than
2.8 tonnes/ha on average (FAO/UN, 2012) (Table 1.1). Wheat is cultivated
in 123 countries and China is currently the world’s leading wheat producer.
Table 1.2 lists the top 10 wheat-producing countries, over the five-year
period 2006–2010.

Among the top 10 wheat-producing countries, China contributed, during
the period 2006–2010, 13.7 % of the world’s wheat production from 8.6 %
of the world’s wheat-growing area, while India contributed 9.8 % of the
production from 10.7 % of the area. China produces a larger amount of
wheat than India (89.0 compared to 63.6 million tonnes per year,
2006–2010) but from 4 % less wheat cultivation area (18.9 compared to
23.5 million hectares per year, 2006–2010). This is mainly due to the
high wheat yield registered in China (4.7 tonnes/ha), second only to
Germany and France with 6.7 and 7.0 tonnes/ha, respectively (FAO/UN,
2012) (Table 1.2).Throughout the last 10 years, wheat production has gradu-
ally increased by approximately 10 %, growing from 585.7 × 106 to 653.7 ×
106 tonnes, mainly due to an improved yield that has been increased by
≈10 % (Table 1.1).

© Woodhead Publishing Limited, 2013

4 Cereal grains for the food and beverage industries

Table 1.2 Wheat production estimates in the 10 leading producing countries;
five-year average 2006–2010

Rank Country Production Area harvested Wheat yield World
(Mt) (Mha) (t/ha) production
(%)

1 China 89.0 18.9 4.7 13.7
2 India 63.6 23.5 2.7 9.8
3 USA 47.0 16.4 2.9 7.3
4 Russian 40.0 18.7 2.1 6.2

5 Federation 29.6 4.4 6.7 4.6
6 France 24.1 5.1 4.7 3.7
7 Chile 19.7 6.4 3.1 3.0
8 Hungary 19.4 7.3 2.7 3.0
9 Canada 19.0 2.7 7.0 2.9
10 Germany 18.0 7.0 2.6 2.8
Total Pakistan 369.4 110.4 3.3a 57.0

aAverage of wheat yield among the 10 leading-producing countries.
Source: Data from FAO/UN (2012).

As reported in Table 1.1, the last 10 years have seen wheat producer
prices increase by 36.5 %, moving from 179.7 US $/tonnes to 283.3
US $/tonnes in 2010. Among the top 10 producer countries, Turkey and
Russian Federation showed the highest (328.4 US $/tonnes) and the lowest
(134.4 US $/tonnes) producer price, respectively. For the leading producing
country China, the producer price for 2009 was equal to 270.9 US $/tonnes
(FAO/UN, 2012).

1.1.2 Phytology, classification and cultivation
Wheat is an annual grass belonging to the Poaceae (Gramineae) family,
tribe Triticae (Zohary, 2000). The wheats currently cultivated are the diploid
T. monococcum (Einkorn wheat; 2n = 14, genetically described as AA
plants), the tetraploids T. dicoccum (emmer wheat) and T. durum (pasta
wheat or hard wheat) (2n = 28, genetically described as AABB plants),
and the hexaploids T. aestivum (soft wheat or bread wheat) and T. spelta
(spelt) (2n = 42, genetically described as AABBDD plants). Currently,
about 95 % of the wheat grown worldwide is bread wheat, with most of the
remaining 5 % being pasta wheat. The latter is more adapted to the dry
Mediterranean climate than bread wheat. Small amounts of other wheat
species (einkorn, emmer, spelt) are still grown in some regions including
Spain, Turkey, the Balkans and the Indian subcontinent. In Italy, these
hulled wheats are together called farro (Szabó and Hammer, 1995), while
spelt continues to be grown in Europe, particularly in Alpine areas (Fossati
and Ingold, 2001).

© Woodhead Publishing Limited, 2013

Wheat and other Triticum grains 5

Wheat for the purpose of trading is classified into distinct categories
according to grain hardness (soft, medium-hard and hard) and colour (red,
white and amber). It may be further subdivided into subclasses based on
growing habit (spring or winter). Each wheat subclass may also be grouped
into grades, which are generally used to adjust the basic price of a wheat
stock by applying premiums or penalties. Wheat grades are indicators of
the purity of a wheat class or subclass, the effects of external factors on
grain soundness (rain, heat, frost, insect and mould damage) and the cleanli-
ness (dockage and foreign material) of the wheat lot. Today, wheat is a
major component of most diets of the world because of its high agronomic
adaptability, nutritional quality, the fact that it can be stored effectively
indefinitely before consumption (provided the water content is below about
15 % dry weight and pests are controlled) and the ability of its flour to
produce a variety of satisfying, interesting and palatable foods.

1.2 Structure of wheat grain

The description that follows is based on bread wheat (T. aestivum). This
species shares many morphological and chemical characteristics with other
wheat species that are used commercially. This section, therefore, may be
considered a useful guide but not an exhaustive description of species other
than T. aestivum. Figure 1.1 shows a caryopsis, or kernel, of wheat in both
longitudinal and cross-sections. The wheat kernel averages ~2.5–3.0 mm in
thickness (or height as it stands on its base), 3.0–3.5 mm in width and
6.0–7.0 mm in length. Wheat kernels average ~30–40 mg in weight (Delcour
and Hoseney, 2010). Wheat grains contains 2–3 % germ, 13–17 % bran and
80–85 % mealy endosperm (all constituents converted to a dry matter basis)
(Anonymous, 2000).

The main morphological characteristics of the wheat kernel are its oval
shape, the embryo at one end and the tuft of hair constituting the brush at
the other. The wheat kernel has a longitudinal crease (an elongated
re-entrant region parallel to its long axis) on its ventral side (opposite the
embryo) and is rounded on the dorsal side (the same side as the embryo)
(Fig. 1.1). The two cheeks formed by the crease, not only form a hiding place
for insects, microorganisms and dust but also make it difficult for the miller
to separate the bran from the endosperm with a good yield. The colour of
the kernel varies from light buff or yellow to red brown according to the
presence or absence of red pigmentation in the seed coat. Purple and even
black seeds are known but are not common. The type and presence of pig-
ments are controlled by three separate genetic loci and thus can be manipu-
lated by the plant breeder (Freed et al., 1976).

The pericarp, which surrounds the whole seed, is composed of several
layers (Delcour and Hoseney, 2010a), including the outer epidermis (cuti-
cule), hypodermis, cross cells, tube cells, seed coat (testa) and nucellar tissue

© Woodhead Publishing Limited, 2013

Crease

© Woodhead Publishing Limited, 2013 Hairs Starch grains
Endosperm
Starch cells
Aleurone cells
Membrane
Testa

Endocarp Crease dirt Plumula
Epicarp sheath
Epidermis or
cuticle Rudimentary
leaves of
Germ plumula

Radicle

Root sheath

Fig. 1.1 Longitudinal and cross-sections of wheat kernel.

Wheat and other Triticum grains 7

(Delcour and Hoseney, 2010a; Khan and Shewry, 2009) (Fig. 1.1). The outer
pericarp is easily detached and, because of its pale membranous appear-
ance, is known to millers as ‘beeswing’. Its removal also aids movements of
water into the kernel. The outer epidermis of the pericarp is 15–20 μm thick
and is composed of long narrow cells (80–300 μm long and 25–48 μm wide
with walls 3–9.5 μm thick) (Bradbury et al., 1956b). The mature hypodermis
lies below the epidermis and forms, together with the epidermis and rem-
nants of the thin-walled parenchyma, the outer pericarp. The inner pericarp
is constituted of intermediate cells, cross cells and tube cells. Neither the
intermediate nor the tube cells completely cover the kernel. The cross cells
measure 100–150 μm long by 15–20 μm wide and 10–15 μm thick and have
their long axis perpendicular to the long axis of the kernel (Delcour and
Hoseney, 2010a). The tube cells (elongated and knobby in outline,
120–130 μm length, 12–15 μm wide, 5–10 μm thick) (Bradbury et al., 1956b)
which form an incomplete layer represent the inner epidermis of the peri-
carp and are confined to a narrow band on the dorsal side, spreading to
provide complete coverage over the embryo and brush ends. The long axis
of the tube cells runs parallel to the axis of the kernel. The tube cells are
not packed tightly and thus have many intercellular spaces. The total peri-
carp has been reported to comprise about 5 % of the kernel and consists of
approximately 6 % protein, 2.0 % ash, 20 % cellulose and 0.5 % fat, with the
remainder being non-starch polysaccharides.

The seed coat and the pigment strand are not the same tissue but,
together, they provide a complete covering around the seed. They control
the water relations between the enclosed seeds and its surroundings at the
maturity stage (Delcour and Hoseney, 2010a). The seed coat is composed
of cells which are 100–191 μm long, 9–20 μm wide and 5–8 μm thick (Brad-
bury et al., 1956b). The seed coat consists of three layers: a thick outer
cuticle, a layer that contains pigments and an inner thin cuticle. The seed
coat consists of two compressed cell layers of cellulose containing little or
no pigment. The nucellar epidermis is about 7 μm thick and tightly bound
to both the seed coat and the aleurone layer.

The endosperm consists of two tissues: the aleurone layer and the mass
of mealy or starchy endosperm within in. The aleurone cells, which enclose
the starchy endosperm and, in modified form, the embryo, occur in one or
more (according to species) continuous layers at maturity. The aleurone
cells are heavy-walled and essentially cube-shaped. They can vary in thick-
ness from 30 to 70 mm within a single kernel, have thick (6–8 mm), double-
layered cellulosic walls and are free of starch at maturity (Bradbury et al.,
1956a) (See Plate I in the colour section between pages 230 and 231). The
aleurone layer, which is generally one cell thick in wheat, completely sur-
rounds the kernel, covering both the starchy endosperm and the germ,
except for that adjacent to the scutellum. Although the aleurone layer is
anatomically a part of the endosperm, the miller regards the aleurone as
the innermost layer of the bran. Aleurone cells contain a large nucleus and

© Woodhead Publishing Limited, 2013

8 Cereal grains for the food and beverage industries

a large number of aleurone granules.They are relatively high in ash, protein,
total phosphor, phytate phosphorus, fat and niacin. In addition, concentra-
tions of thiamine and riboflavin are higher in the aleurone than in the other
parts of the bran. Furthermore, the aleurone layer is particularly rich in
enzymes, which play a vital role in the germination process (Anonymous,
2000). Over the embryo, the aleurone cells are modified, becoming thin-
walled cells, and may not contain aleurone granules (Delcour and Hoseney,
2010a). The aleurone cells are also common as a storage reserve for lipid
droplets. Most of the aleurone layer is removed as part of the bran during
roller milling (Dexter and Wood, 1996).

The wheat embryo, also called germ by millers, makes up 2.5–3.5 % of the
kernel and lies on the lower dorsal side of the caryopsis. At grain maturity, it
comprises an embryonic axis (shoot or epicotyls, mesocotyl and radical) and
a scutellum, which is considered to be homologous with a cotyledon (Khan
and Shewry, 2009).The scutellum lies between the embryonic axis and endo-
sperm, and its name derives from its shield-like shape. The germ is relatively
high in protein (25 %), sugar (18 %) mainly sucrose and raffinose, and ash
(5 %). It also has the highest concentration of lipids (16 %) and hence lipid-
soluble vitamins E of all the components of the wheat kernel, with levels of
up to 500 ppm (Delcour and Hoseney, 2010a). It also has the highest moisture
content among constituents of the mature grain (Song et al., 1998), but not all
water-soluble vitamins are found in their highest concentrations here
(Michael, 2009). Nevertheless, the use of wheat germ is still challenging
because of its poor stability and the presence of anti-nutritional factors such
as: (i) raffinose which is not digested by pancreatic enzymes but metabolized
by gas-producing bacteria of the large intestine, thus causing disorders such
as flatulence (Rizzello et al., 2010); (ii) phytic acid which markedly decreases
the mineral bioavailability (Febles et al., 2002); and (iii) wheat germ aggluti-
nin (WGA) which is responsible for the hyperplastic and hypertrophic
growth of the small bowel and pancreas (Matucci et al., 2004).

The starchy endosperm occurs as a solid mass occupying the centre of
the kernel and represents the largest morphological component in all
cereals, and it is also the component with the greatest value (Evers and
Millar, 2002). It is composed of three types of cells that vary in shape, size
and location in the kernel (Greer et al., 1951). Peripheral or subaleurone
cells are the first row of cells inside the aleurone layer, which they resemble
in size (60 μm in diameter). Next are several rows of prismatic starchy
endosperm cells (130–200 μm long, 40–60 μm wide). They extended inward
to about the centre of the cheeks. Central cells (2.6 μm thick, 72–144 μm
long, 70–120 μm wide) occur in the centre of the cheeks (Bradbury et al.,
1956b; Michael, 2009) and they are more irregular in shape and size than
the other cells. The endosperm cell walls comprise about 75 % polysaccha-
ride, the latter comprising about 70 % arabinoxylans, 20 % (1–3)(1–4)β-d-
glucans, 7 % β-glucomannan and 2 % cellulose (Bacic and Stone, 1980).
Proteins are also presents at a level of about 15 %. Starch and proteins, two

© Woodhead Publishing Limited, 2013

Wheat and other Triticum grains 9

major storage reserves, make up the bulk of the endosperm. In the starchy
endosperm, starch granules are surrounded by the matrix protein (Plate I).
The protein is mostly gluten, the storage protein of wheat. The latter, in
mature cells appears as a continuous matrix rather than specific individual
bodies in which form it develops. The concentration of starch and matrix
proteins also varies according to cell position.

The peripheral cells have the lowest starch content, while the protein
percentage is highest in these cells. The increasing starch content found
towards the centre of the cheeks causes progressive dilution of other com-
ponents as well as protein (Evers, 1970).

1.3 Wheat carbohydrate composition and properties

1.3.1 Wheat composition: an introduction
Wheat is one of the major grains in the diets of about a half of the world’s
population and therefore has an important impact on their nutritional
quality. Like other typical cereal grains, the wheat kernel contains three
main anatomical parts – the embryo, the endosperm and the pericarp, which
covers the endosperm.The outermost bran layers, representing the pericarp,
are fibre rich. Starch and proteins are concentrated in the endosperm, while
the germ is high in fat. The bran and germ fractions are also high in vitamins
and minerals. The nutritional role of wheat constituents needs particularly
to be taken into account when designing a process to transform wheat into
bakery products. Table 1.3 indicates fairly typical chemical constituent dis-
tributions in the wheat kernel. It must be realized, however, that these
values are indicative, and that the actual composition may vary above or
below these figures depending on the genotype (variety) (Hinton, 1953;
MacMasters et al., 1971; Morrison, 1978; Belitz et al., 2009), and the milling
process used, an evolution of which is illustrated in Fig. 1.4 with a further
description in Section 1.6.1 (Historical background).

At maturity, the wheat kernel consists of 85 % (w/w) carbohydrates (of
which about 80 % is starch) found only in the starchy endosperm. Wheat
also contains mono-, di- and oligosaccharides at a level of 7 %, mainly con-
centrated in the aleurone layer. Fructans are also presents in the starchy
endosperm and embryonic axis, while 12 % of the wheat kernel consists of
cell wall polysaccharides, which are found in all kernel tissues (Henry and
Saini, 1989; Knudsen, 1997; Bruce and Matthew, 2009). Wheat carbohy-
drates have been studied extensively over the years in terms of structure
and functionality as related to particular end-products like bread and
bread-type products.

1.3.2 Starch
Starch is formed out of carbon dioxide and water by the process of photo-
synthesis and is deposited in plant cells as microscopic particles of varying

© Woodhead Publishing Limited, 2013

Table 1.3 Chemical constituent distributions as % in kernel fractions of wheat

Distribution of chemical constituents in wheat ( %)

© Woodhead Publishing Limited, 2013 Fractions % of bCarbohydrates

kernel Pentosans and cProtein bMinerals dFat Vitamins
weighta hemicellulose

Cellulose Starch Sugar

Bran 3.8–4.2 43.1 35.2 14.1 7.6 – 7 5.1–5.8 15
Pericarp 5.0–8.9 – – 0.7–1.0 –
Testa (hyaline) 0.2–1.1 – – –– 2.5 – 0.2–0.5 –
Aleurone 4.6–8.9 – 61 6.0–9.9 –
Endosperm 74.9–86.5 2.4 – –– 1.5 20 0.75–2.2 83
Germ 2.0–3.9 12 2–3
1.0–1.6 15.3 – – – 14.2 – 11.3 –
Embryonic axis 1.1–2.0 – – 10.0–16.3 –
Scutellum – 0.3 95.8 1.5 74.5 12.6–32.1

16.8 31.5 36.4 3.0

– –– –

– –– 4.5

aData from MacMasters et al. (1971).
bData from Belitz et al. (2009).
cData from Hinton (1953) and MacMasters et al. (1971).
dData from Morrison (1978).

Wheat and other Triticum grains 11

A-type granule starch

B-type granule starch

50.0 μm
Fig. 1.2 Confocal laser scanning microscopy (CLSM) of wheat starch granules.

Large (A-type) and small (B-type) starch granules; magnification = 40x.

size and conformation. In wheat and other higher plants, starch is formed
in amyloplasts, each of which contains one starch granule. Wheat has two
types and sizes of starch granules. The large lenticular (lens-shaped) gran-
ules are 25–40 μm in the long dimension; the small, spherical granules are
5–10 μm in diameter. Figure 1.2 shows a confocal laser scanning electron
micrograph (CLSM) of starchy endosperm in which it is possible to observe
the two types of wheat starch granules. Wheat starch granules comprise
25 % amylose (Zeng et al., 1997) and 75 % amylopectin. In addition to
amylose and amylopectine, wheat starch granules usually contain small
amounts of proteins and lipids. Amylose is composed of a glucopyranose
unit linked through α-d-(1→4) glycosidic linkages and shows many of the
properties of a linear polymer. It has historically been considered to be a
linear polymer (average chain length of 270 units) (Takeda et al., 1987) with
a degree of polymerization of approximately 3000 or less (Fig. 1.3), however,
it is now known that amylose contains a limited amount of branching
involving α-d-(l-→6)-glucosidic linkages at the branch points (0.2–0.8 % of
linkages). The second component, amylopectin, is a branched polymer con-
taining about 4–6 % of α-d-(1→6)-glucosidic linkages as the branch points.
The average chain length is 20–25 units with an average degree of poly-
merization in the thousands, and molecular weight in the millions (Fig. 1.4).
Amylopectin molecules are radially orientated in the granules and are
constructed of unit chains containing 18–25 (1→4)-linked α-d-glucopyranosyl

© Woodhead Publishing Limited, 2013

12 Cereal grains for the food and beverage industries

(a) DP < 3000, CL 50–500

(b) DP > 5000, ACL 20–25

Fig. 1.3 Schematic representation of the structural elements of amylase (a) and
amylopectine (b). DP = degree of polymerization; CL = chain length; ACL = average

chain length.

Saddlestone

Slab mill

Push mill

3660–80 BC

Lever mill

19 BC

Hourglass mill

Millstones

Quern mill

Delian mill

Fig. 1.4 Possible lines of evolution from the hand-operated saddlestone to the
powered millstone.

unit per chain. Hundred of these units are linked together by α-(1→6)-
linkages to form amylopectin.

On the basis of X-ray diffraction experiments, starch granules are said
to have a semi-crystalline character, which indicates a high degree of ori-
entation of the glucan molecules.About 70 % of the mass of a starch granule
is regarded as amorphous and ca 30 % as crystalline.The amorphous regions

© Woodhead Publishing Limited, 2013

Wheat and other Triticum grains 13

contain the main amounts of amylose, but also a considerable part of the
amylopectin. The crystalline regions consist primarily of amylopectin.

Most of the functional attributes of starch can be related to the
temperature-dependent interactions of starch with water in the processes
known as gelatinization, pasting and gelation (retrogradation) (Stone and
Krasowski, 1981; Atwell et al., 1988). As starch is heated (53–65 ºC) in the
presence of water, the granules swell and imbibe water, and hydrogen bonds
are disrupted with eventual irreversible loss of crystallite structure (gelati-
nization). Pasting generally refers to changes in viscosity just before, during
and after gelatinization. Upon further heating (pasting or cooking), swelling
continues and the amylose and portions of the amylopectin leach from the
granule producing a viscous suspension. As a starch–water system cools,
starch polymer–water hydrogen bonds are replaced with polymer–polymer
hydrogen bonds, and a gel network is formed. At a molecular level, this
re-association process is more aptly termed retrogradation. Zeng et al.
(1997) showed how the variation in amylose can largely influence the gela-
tinization, pasting and gelation properties of wheat starch. Retrogradation
is most rapid with amylose and much slower and more incomplete with
amylopectin due to the short chain length of its branches. Nowadays, gela-
tinization temperature, paste viscosity and swelling power of starch have
proved to be useful diagnostics of starch properties, that can be used as
predictors of end-use functionality in industrial and food applications
(Crosbie et al., 1992; Zeng et al., 1997; McCormick et al., 1995). The damage
caused to starch during milling is also another important contributor to the
end-use functionality of wheat, with damaged granules absorbing more
water, the damage allowing more rapid water movement into the granule
remnants. Gelatinization thus proceeds more rapidly. With regard to this,
Dexter et al. (1994) showed how flours containing damaged starch per-
formed less well in the remix-to-peak baking test (long bulk fermentation),
a standard test used for evaluating the baking performance of bread wheat.
Loaf volume and crumb structure of the bread were negatively affected.

1.3.3 Dietary fibre
As defined by Gebruers et al. (2008) and Prosky (2001) ‘dietary fibre (DF)
is the edible parts of plants or analogous carbohydrates, that are resistant
to digestion and absorption in the human small intestine with complete or
partial fermentation in the large intestine.’ Dietary fibre can be divided into
soluble dietary fibre (SDF) and insoluble dietary fibre (IDF) where the
SDF forms a solution when mixed with water, whereas IDF does not form
solutions (Elleuch et al., 2011).

The most important wheat DF components are the non-starch polysac-
charides arabinoxylan (AX), mixed-linkage β-glucan (further referred to as
β-glucan) and cellulose, and the non-polysaccharide compound lignin, all
of which are cell wall components. The HEALTHGRAIN study, financially

© Woodhead Publishing Limited, 2013

14 Cereal grains for the food and beverage industries

supported by the European Commission in the Communities 6th Frame-
work Programme (FP6–514008), determined the levels of dietary fibre in
wheat. The dietary fibre mainly derives from cell wall polymers: AX
(approximately 70 % of the starchy endosperm cell wall dry matter (dm)
weight), smaller amounts of (1–3)(1–4)β-d-glucans (approximately 20 %)
and other components. AX makes up around 2 % of the starchy endosperm
dm, of which one-quarter to one-third is water extractable. The non-
extractable form of AX is particularly rich in bound phenolic acids which
form oxidative cross-links. These bound phenolic acids, predominantly
ferulic acid, represent about 77 % of the total phenolic acid fraction. The
most interesting property of cereal phenolic compounds is their antioxidant
activity (Vitaglione et al., 2008).

Vitaglione et al. (2008) report that free phenolic compounds, mainly
released from SDF by the action of intestinal and microbial esterases, can
be absorbed to various extents through the intestine and, passing in the
bloodstream, can exert their health benefits in the whole body.

The peripheral layers (aleurone and intermediate and outer pericarp
layers) and germ are richer in AX than the starchy endosperm, with the
highest levels occurring in the outer pericarp (ca 40 %) (Barron et al., 2007).
Apart from their functional relevance, AX are also important from a tech-
nological point of view because they strongly affect both wheat functional-
ity during cereal processing, for example in bread-making (Goesaert et al.,
2005), and gluten–starch separation (Frederix et al., 2004; Van Der Borght
et al., 2005).

Compared to other cereals such as barley, (1→3)(1→4) β-glucan is found
only in small quantities in wheat grain. Dependent on the variety, amounts
of β-glucan between 0.52 and 1.47 % (dwb) have been reported (Prentice
et al., 1980; Åman and Hesselman, 1985; Beresford and Stone, 1983;
Genç et al., 2001). Unlike the cereals which are rich in β-glucan, such as
oats and barley, the highest concentrations of β-glucan in wheat are found
in the inner aleurone cell walls and subaleurone endosperm cell walls
(Izydorczyk et al., 2000). β-Glucan is a linear homopolymer arranged in
blocks of consecutive β-(1→4)-linked d-glucose residues separated by
single β-(1→3)-linkages. The chain mainly consists of cellotriosyl (58−72 %)
and cellotetraosyl (20−34 %) units. Although the distribution of these tri-
saccharide units is random (Staudte et al., 1983), the repetition of the cel-
lotriosyl units gives wheat β-glucans a more highly ordered confirmation,
one which might even promote self-association. This would also explain
the greater gelling capacity and the poorer solubility of wheat β-glucans
compared to other cereal β-glucans (Li et al., 2006). The endosperm con-
tains ca 0.3 % of β-glucan (dm) (Henry, 1987). Most β-glucan is found in
the aleurone layer [ca 23 % of cell wall polysaccharide fresh weight (fw)]
(Barron et al., 2007).

Like β-glucan, cellulose is a homopolymer of glucose. However, all resi-
dues are linked by β-1,4-linkages only. Cellulose is found in walls of all cells

© Woodhead Publishing Limited, 2013

Wheat and other Triticum grains 15

of the grain tissues. The total content in grain is about 2 % (dw). In flour,
the cellulose content is as low as 0.3 % (Fraser and Holmes, 1956). Cellulose
is a very abundant cell wall polysaccharide in the outer pericarp and inter-
mediate layers, which contain ca 25 and 12.2 % of fresh weight of this
polysaccharide, respectively (Barron et al., 2007). Lignin is described as the
‘glue’ that holds together the bundles of cellulose and hemicellulose in
mature plant cell walls. It is an amorphous, aromatic hydrocarbon polymer,
formed by condensation of phenylpropane subunits. Lignin itself is structur-
ally complex and properly speaking is not one compound but rather a whole
class of plant cell wall materials. It contributes relatively little to the water-
binding capacity of fibres. On the other hand, lignin might bind bile acids
and cholesterol in the gut. Wheat wholemeal typically has a lignin concen-
tration of ca 2 % of dry matter (Knudsen, 1997).

1.4 Wheat protein composition and properties

Grain protein content (GPC) is one of the major characteristics used to
classify wheat since it can be related to aspects of end-use quality. Several
authors report a clear relationship between flour protein content and loaf
volume of bread (Schofield and Booth, 1983; Bushuk 1985; Bushuk and
Bekes, 2002). GPC also influences the stickiness of spaghetti (Del Nobile
et al., 2005) and the texture and cooking loss in noodles (Hu et al., 2007).
Growing conditions, environment and fertilizer use have a significant effect
on the protein content of wheat which varies from 7 to 20 % in a single
variety. Generally, the wheat protein content ranges from 6 % to more than
27 %, although most commercial samples show a protein content of between
8 and 16 % (Delcour and Hoseney, 2010a). Generally the protein content
is negatively correlated with grain yield; however, excellent yields and high
protein contents are combined in some varieties.

Several authors reported that the starch content of American wheat
varieties is in the range of 61.2–72 % (Pomeranz and MacMasters, 1968;
Cerning and Guilbot, 1974), and that the starch content appears to be
inversely related to the protein content (Hopkins and Graham, 1935). Gen-
erally, soft wheat varieties have higher starch contents (69 %) than hard
wheat varieties (64 %) (Miller, 1974). Low-protein wheat is high in starch
content, irrespective of whether it is soft or hard. On the other hand, Euro-
pean wheat varieties tend to have higher mean starch contents (62–75 %)
and lower protein contents than American varieties (Cerning and Guilbot,
1974). Agricultural conditions, such as the climate, level of fertilization and
soil properties, have an influence on the starch and protein contents (Delcour
and Hoseney, 2010). When 10 varieties of French wheat were grown at the
same time in three regions of France with different climates, for example,
the starch content was found to vary from 71.4 to 75.0 % for the same
variety (Cerning and Guilbot, 1974). In bread wheats, the endosperm varies

© Woodhead Publishing Limited, 2013

16 Cereal grains for the food and beverage industries

both in texture (hardness) and appearance (vitreousness). In general, high-
protein hard grains are vitreous, whereas low-protein soft grains tend to be
opaque.

1.4.1 Classification based on solubility
Osborne, in his classic studies of plant proteins carried out at the end of the
19th century and the start of the 20th century, introduced a solubility-based
classification of plant proteins using sequential extraction in the following
series of solvents: (i) water, (ii) dilute salt solution, (iii) aqueous alcohol and
(iv) dilute acid or alkali. Using this Osborne classification scheme, wheat
proteins were classified as albumins (water soluble), globulins (soluble in
dilute salt solution), gliadins (soluble in aqueous alcohol solution) and
glutenins (soluble in dilute acid or alkali solution), respectively. However,
a significant fraction of wheat proteins was excluded from the Osborne
fractions. Moreover, biochemical and genetic analysis gradually demon-
strated that Osborne fractionation does not provide a clear separation of
wheat proteins. Nevertheless, Osborne fractionation is still extensively used
in studies relating protein composition to functionality in bread-making.
Furthermore, due to its relative simplicity, this fractionation method is often
very useful as an initial separation step to obtain semi-pure protein frac-
tions (Goesaert et al., 2005).

1.4.2 Classification based on functionality
From a technological point of view, two distinct groups of wheat proteins
can be distinguished: the gluten proteins (80–85 % of total wheat protein),
which play a major role in bread-making, and the highly heterogeneous
group of non-gluten proteins (15–20 % of total wheat protein) which play
either no role or only have a minor role in bread-making. Gluten proteins
form the major class of wheat storage proteins and are initially deposited
in discrete protein bodies (Field et al., 1983) that later form the protein
matrix surrounding the starch granules in the wheat kernel starchy
endosperm.

Gluten proteins can be divided into two functionally distinct groups, the
monomeric gliadins (mainly contributing to dough viscosity and extensibil-
ity) and polymeric glutenins (mainly providing cohesiveness and elasticity
to dough) (Joye et al., 2009). The non-gluten proteins are distinct in water-
soluble albumins and water-insoluble globulins (Osborne, 1907). The latter
are traditionally considered to be soluble in dilute salt solutions even if
some hydrophobic lipid-binding proteins may require more hydrophobic
solvents (Singh et al., 1990) and some globulins (triticins) are only soluble
in salt solutions at higher temperatures (Singh and Shepherd, 1987).

The majority of the non-gluten proteins are monomeric with a molecular
weight (MW) that is lower than 25 000. Most of the non-gluten proteins are

© Woodhead Publishing Limited, 2013

Wheat and other Triticum grains 17

structural proteins or metabolic proteints (i.e. enzymes); however, one
group, polymeric globulins, make up a minor fraction (about 5 % of total
protein) of the wheat storage proteins (Singh et al., 1991). Even though
some endogenous enzymes, such as peptidases (EC 3.4) (Caballero et al.,
2007), amylases (EC 3.2.1.1) (Lagrain et al., 2008) and xylanases (EC 3.2.1.8)
(Courtin and Delcour, 2002; Dornez et al., 2007), and some inhibitors, such
as xylanase inhibitors (Debyser et al., 1997, 1999) and amylase inhibitors
(Zawistowska et al., 1988; Klockiewiczkaminska et al., 1995; Sorensen et al.,
2004) have the potential to influence final bread quality, their importance
in bread-making is largely unknown (Joye et al., 2009).

Gluten protein can be divided in two fractions: glutenin polymers, a
heterogeneous mixture, with MWs between 80 000 and several million
(Kasarda, 1989) and monomeric gliadins, with MWs ranging from 30 000 to
80 000 (MacRitchie et al., 1990). In contrast with the non-gluten proteins,
gluten proteins are poorly soluble in water or dilute salt solutions, mainly
due to the high levels of non-polar amino acids and glutamine they contain
and the low levels of amino acids with ionizable side chains. Mixing can
change the solubility of gluten protein, particularly the solubility of the
glutenin polymers, which are difficult to dissolve due to their large size. The
increase in extractability must be due to changes in the gluten network.

Glutenin proteins are able to form S–S cross-links and therefore form
oligomeric structures. Depending on the shear strain rate, mixing can cause
scission of such bonds, initiating changes in the structure of the polymer
(Macritchie, 1975; Weegels et al., 1996). This indicates the important role of
mixing in the formation of the gluten protein network in dough. When
kneading/mixing flour with water, gluten proteins enable the formation of a
cohesive, visco-elastic dough that is capable of holding gas produced during
fermentation and oven-rise, resulting in the typical open foam structure of
bread after baking. Finney and Barmore (1948) showed that wheat flour
bread-making performance is linearly correlated with flour protein content
and thus with gluten protein content because this protein fraction increases
much more than the non-gluten protein fraction with increasing grain protein
content (Delcour and Hoseney, 2010). Thus, a high quantity of gluten pro-
teins is important. However, the linear relationship between protein content
and bread-making performance depends on the wheat variety (Finney and
Barmore, 1948), suggesting that gluten protein quality is also relevant.

Proteins are not uniformly distributed in the kernel, with variation occur-
ring in both protein composition and content. The protein contents of
diverse morphological parts of the kernel are reported in Table 1.3. It is
clear that the starchy endosperm proteins alone represent three-quarters
of the total grain protein. The starchy endosperm proteins are characterized
by low levels of basic amino acids and high contents of proline and gluta-
mine, while the germ and aleurone layer are characterized by lower levels
of glutamine and proline and high levels of asparagine and arginine in the
germ and aleurone layer, respectively (Table 1.4) (Jensen and Martens,

© Woodhead Publishing Limited, 2013

Table 1.4 Amino acid composition of botanical component of wheat and recommended levels of essential amino acids for adult humans

Amino acid (g/100 g of Botanical components of wheata FAO/WHO/UNU
protein) adult recommendationb
Grain

Pericarp Testa Aleurone Endosperm Germ

© Woodhead Publishing Limited, 2013 Non-essential 6.6 5.9 5.9 3.5 7.7 3.8 1.5
Alanine 9.5 7.9 7.9 4.2 10.4 5.4 3.0
Aspartic acid 15.8 22.6 20.9 35.2 13.9 32.5 5.9
Glutamic acid 7.9 6.5 5.8 3.6 7.4 4.4 4.5
Glycine 6.6 7.6 6.3 12.9 4.8 10.8 2.2
Proline 3.9 4.0 2.9 2.7 3.0 3.5 1.6
Serine 5.1 6.5 11.1 3.6 8.7 4.8 0.6
Arginine 3.8
1.6 2.7 3.4 2.0 2.9 1.2 1.9
Essential 5.1 4.3 3.6 4.0 4.1 4.2
Histidine 8.4 8.8 6.5 7.3 7.5 7.6 2.3
Isoleucine 4.6 4.1 4.8 2.1 8.3 2.9 0.6
Leucine 3.9
Lysine 2.4 1.6 1.6 4.2
Methionine + cysteine 1.6 2 1.9
Methionine 5.4 5.5 3.8
Cysteine 3.7 3.6 3.3 2.3
Phenylalanine + tyrosine 4.0 3.5 2.9
Phenylalanine 4.0 0.7 4.0 5.3 4.1 5.3
tyrosine 5.5 4.3 5.3 3.7 3.2 3.3
Threonine 2.2 4.0 2.7
Tryptophan 2.0 1.7 1.1
Valine 4.2 6.5 4.5

a Adapted from Jensen and Martens (1983).
b FAO/WHO/UNU (2007).

Wheat and other Triticum grains 19

1983). Since the quality and content of proteins differ between the various
parts of the kernel, flour composition can be influenced greatly by the
milling extraction rate.

1.4.3 Nutritional quality
Despite the relatively low protein content of wheat (usually 8–15 %), it still
provides as much protein for human and livestock nutrition as the total
soybean crop, estimated at about 60 million tonnes per annum (Shewry,
2007). Therefore, the nutritional importance of wheat proteins should not
be under-estimated, particularly in less developed countries where bread,
noodles and other products (e.g. bulgur, couscous) may provide a substan-
tial proportion of the diet. Protein nutritional quality is determined by its
contents of essential amino acids, those which cannot be synthesized by
animals and hence must be provided in the diet. Ten amino acids are strictly
essential: lysine, isoleucine, leucine, phenylalanine, tyrosine, threonine, tryp-
tophan, valine, histidine and methionine. However, cysteine is often also
included as it can only be synthesized from methionine (which is itself
essential), with combined values for these sulphur-containing amino acids
being presented. Similarly, combined values for the biosynthetically related
aromatic amino acids phenylalanine and tyrosine are often presented.

A comparison of the amino acid composition of wheat flour with the
levels of essential amino acid recommended by the FAO/WHO/UNU for
adults shows that wheat is deficient in only lysine, and that some essential
amino acids are present in considerably higher amounts. However, the
lysine content of wheat also varies significantly with the values shown in
Table 1.4 being typical of grain with a high GPC and the proportion increas-
ing to over 3 g/100 g protein in low-GPC grain (Mosse and Huet, 1990).
The lower lysine content of high-protein grain results from proportional
increases in the lysine-poor gluten proteins when excess nitrogen is avail-
able (for example, when fertilizer is applied to increase grain yield and
protein content) and also accounts for the lower lysine content of white
flour (the gluten proteins being located in the starchy endosperm tissue).
Attempts have been made over the last 50 years to increase the content of
lysine in cereals, but these have met with little success due to the association
of the improved nutritional quality with low yield and poor agronomic
performance. However, nitrogen application also increases cereal yields and
the farmer must therefore balance the optimum nitrogen requirement for
yield with the commercial requirements for either high- or low-protein
grain.

1.4.4 Wheat allergy and coeliac disease
Despite their valuable contribution to our diet, wheat-based foods cause
health problems in a minority of the population, in particular due to coeliac

© Woodhead Publishing Limited, 2013

20 Cereal grains for the food and beverage industries

disease (CD) but also due to various other forms of allergy, such as baker’s
asthma, atopic dermatitis, urticaria and wheat-dependent exercise-induced
anaphylaxis (WDEIA) (Shewry, 2009). Both CD and wheat allergy are
characterized by a clinically abnormal response that is induced in suscep-
tible persons by wheat components, which are well tolerated by the vast
majority of the population. CD is the most common food-induced enter-
opathy in humans (Vader et al., 2003). It is caused by intolerance to wheat
gluten and similar proteins of barley and rye in genetically susceptible
individuals (Arendt et al., 2011). It is characterized by immune-mediated
enteropathy (villous flattening), resulting in maldigestion and malabsorp-
tion of nutrients. Regarding wheat allergy, the predominant wheat proteins
responsible for bakers’ asthma are a class of α-amylase inhibitors (also
called chloroform methanol soluble or CM proteins) (Salcedo et al., 2004),
while the major allergens in wheat associated with WDEIA are a group of
proteins called ω5-gliadins (part of the protein gluten fractions) (Matsuo
et al., 2004). However, other forms of wheat allergy have also been reported,
with the proteins responsible including gluten proteins, CM proteins and
non-specific lipid transfer proteins (Tatham and Shewry, 2008). In all cases,
at present the only successful and safe treatment is the complete avoidance
of foods containing the provocative proteins.

1.5 Other constituents of wheat

Wheat constituents like lipids and minerals are generally defined as ‘minor’
constituents. However, this definition does not indicate that they are of less
importance than any others, reflecting rather a quantitative relationship
only.

1.5.1 Lipids
In contrast to the starch and protein fractions, the lipid fraction is a minor
component of the wheat kernel, constituting about 3–4 % of the weight of
wholewheat. When the protein fraction is removed from wheat flour, dough
and bread-making properties are totally lost. In contrast, these are totally
retained when the lipid fraction is removed from the flour. However, lipids
do play an important role in dough mixing and baking processes, contribut-
ing to the stabilization of the gas-cell structure due to their interaction with
gluten proteins, thus having a role in loaf volume and final texture. Lipids
are distributed throughout the wheat kernel (Table 1.3) as structural com-
ponents of biomembranes and organelles and as spherosomes (oil droplets
< 5 μm in diameter) bounded by monolayer membranes, on oil-rich tissues
such as embryonic axis, scutellum and aleurone (Morrison, 1978). The
classes of wheat lipids are the same as those in other cereals (Corke, 2004).
The distribution of lipids within the wheat kernel varies widely (Table 1.3).

© Woodhead Publishing Limited, 2013

Wheat and other Triticum grains 21

One-third of the total lipid fraction is located in the germ, which accounts
for only about 4 % of the total grain by weight; therefore, the germ has the
highest lipid content.

Based on solubility in selective extraction conditions, lipids are classified
as starch lipids (SL) and free and bound non-starch lipids (NSL) (Delcour
and Hoseney, 2010). NSL, representing a large number of classes, comprise
approximately two-thirds to three-quarters of the total lipids of wheat flour
and consist predominantly of glycolipids (25 %), as well as other non-polar
lipids (60 %) and phospholipids (15 %). The non-polar lipids are mainly
present in the free NSL fraction, while the glyco- and phospholipids are
mainly associated with proteins and present in the bound NSL fraction
(Delcour and Hoseney, 2010; Every et al., 1998). The SL also represents a
large number of classes: 9 % non-polar lipids, 5 % glycolipids and 86 % phos-
pholipids, clearly the largest fraction. Lysophoshatidylcholine or lysolecithin
are the major constituents (85 %) of the phospholipids in starch.Apart from
them, other lipids in wheat include sterols and lipid-associated compounds
such as carotenoids and tocopherols. Although carotenoids are very minor
constituents, the colour contributed by carotenoids is an important factor in
the use of cereal grains in food production, particularly in the use of durum
wheat for pasta-making. Moreover, certain carotenoids, including α-, β- and
γ-carotene, are precursors of vitamin A (retinol) and are converted into
vitamin A in the intestinal mucosa, even though they have no intrinsic activ-
ity. Carotenoids, as scavengers of free radicals, protect important biomole-
cules in the human body, such as proteins, membrane lipids and DNA, from
oxidative damage, thus reducing the risk of suffering from several chronic
diseases (Yu et al., 2002).The non-polar lipids are mainly concentrated in the
outer layers of the kernel (bran and aleurone layers). The major fraction of
wheat grain, endosperm, has a significantly lower lipid content than the
other fractions. Hence, the lipid composition and content in the flour can
differ, depending on the milling process and the flour yield.

The fatty acids (FA), which are made up of carboxylic acids with long-
chain hydrocarbon side groups, are major components of various lipids.
Most of cereal grain lipids are rich in unsaturated FA and often polyunsatu-
rated fatty acid (PUFA). Some PUFA are essential fatty acids (EFA), for
example linoleic (C18 :2) and linolenic (C18 :3), which constitute 50–65 %
and 1.9–5.3 % of total FA, respectively (Bruce and Matthew, 2009). They
are called essential fatty acids since they cannot be synthesized by humans,
due to the lack of desaturase enzyme required for their production, and
because EFA are fundamental constituents for the formation and develop-
ment of healthy cell membranes and nervous system and their proper
functioning. Only 20–25 % of wheat lipids are saturated FA. The saturated
FA found in wheat are palmitic acid (C16 :0) (17–24 %) and stearic acid
(C18 :0) (1–2 %) (Eliasson and Larsson, 1993; Delcour and Hoseney, 2010).
Although the total amount of FA is relatively low in wheat, its composition
is excellent for human dietary needs (Delcour and Hoseney, 2010a). Wheat

© Woodhead Publishing Limited, 2013

22 Cereal grains for the food and beverage industries

Table 1.5 Mineral compositions of several cereal grains

Minerals Composition (mg/100 g)
Wheat Rye Barley Oats Rice Corn Sorghum

Manganese (Mn) 5.5 7.5 1.8 56 0.6 1.5
Copper (Cu) 0.8 0.9 0.9 0.5
Iron (Fe) 6 9 6 4 0.3 0.2 6
Magnesium (Mg) 180 130 140 150
Calcium (Ca) 60 70 90 72 20
Potassium (K) 580 520 630 400
Phosphorus (P) 410 380 470 140 90 140 405

95 68 30

460 340 330

340 285 310

Source: Adapted from Delcour and Hoseney (2010b).

lipids are minor constituents and yet play critical roles in determining wheat
quality. However, the definition of wheat quality has so many facets. In
general, polar lipids in wheat and/or flour free lipids are an excellent loaf
volume improver and mixing time and mixing-tolerance enhancer, while
non-polar lipids are essential for restoring the surface firmness of cooled
noodles, and polar lipids increase the breaking resistance of dry noodles to
a greater extent than non-polar lipids.

1.5.2 Minerals
Minerals form a small part of the wheat kernel, and an even smaller propor-
tion of the endosperm (about 1 %). Minerals from cereals are poorly uti-
lized by humans and other monogastric animals because some endogenous
and exogenous factors decrease the absorption of minerals from plant foods
(Erdman, 1981). Some fibre components and certain amino acids and pro-
teins chelate minerals (Erdman, 1981).The mineral contents of cereal grains
are affected by a number of factors, including soil, climate and cultural
practices (Dikeman et al., 1982). Table 1.5 lists the mineral composition of
wheat in comparison with other cereal grains. Major constituents of the
mineral fraction are the phosphates and sulphates of K, Mg and Ca. There
are also significant quantities of Fe, Mn, Zn and Cu, as well as trace amounts
of many other elements. The result of one extensive set of analyses is
reported in Table 1.6. In general, most of the minerals (61 % of the total)
(Table 1.3) are concentrated in the aleurone layer. Hemicellulose, cellulose,
lignin, found in wheat fibre as well as the fibres of other cereals, can influ-
ence binding of some minerals (Camire and Clydesdale, 1981). Lignin can
bind great quantities of Ca, Zn, Fe, and Mg, while cellulose binds only small
quantities (Camire and Clydesdale, 1981).

Idouraine et al. (1996) reported that dietary fibre can limit mineral bio-
availability by bonding, diluting and trapping minerals within dietary fibre

© Woodhead Publishing Limited, 2013

Wheat and other Triticum grains 23

Table 1.6 Mineral and phytate content of wheat kernel

Content in kernel or part

Minerals/compounds Whole
kernel
Germ Endosperm Aleurone Hull

Total phosphorus (P) (%) 0.42 1.66 0.11 1.39 0.08
Phytate P (%) 0.32 1.10 0.001 1.16 0
Zinc, (Zn) (ppm) 40.4 222 14.1 119 88.7
Iron (Fe) (ppm) 54.6 235 21.5 189 110
Manganese (Mn) (ppm) 56.4 402 8.80 130 182
Copper (Cu) (ppm) 4.25 18 2.80 12 22.6
Calcium (Ca) (ppm) 335 1760 173 730 2570
Magnesium (Mg) (%) 0.15 0.54 0.02 0.58 0.13
Potassium (K) (%) 0.37 0.91 0.12 1.10 0.24

Source: Adapted from O’Dell et al. (1972).
Note: The kernel was composed of 3.5 % of germ, 70.5 % endosperm, 23 % aleurone and 3 %
hull. All analyses reported on a dry weight base.

particles. Wheat bran binds significantly more Ca than rice bran and oat
fibre because wheat bran has more specific sites for Ca than the other fibre
sources (Idouraine et al., 1996). All four elements (Ca, Zn, Fe and Mg) are
bound to fibre to a greater extent alone than in combination. In other words,
the binding capacity of fibre sources is significantly affected by the presence
of other minerals (Anglani, 1998).

1.6 Flour milling

Wheat may be used whole in various ways for human food, but usually it
is ground and/or fractionated in preparation for further processing. The
main purpose of milling is to render the wheat grain more accessible as a
food, by increasing palatability. This is achieved through a series of size
reduction and separation processes. Separation ensures the removal of the
bran, which consists of large flakes comprising the outer layers of the kernel
and adhering aleurone, and oil-rich germ components from the starchy
endosperm. Thus this step minimizes the possibility of the flour becoming
rancid during storage and its shelf-life being dramatically reduced and also
improves the palatability and digestibility of the final food products made
from the flour, by removing the bran, which is indigestible. The size reduc-
tion process enables enzymatic and cooking processes to be carried out
more effectively. Flour production principally consists of grinding (milling)
and sifting (separation) of the grain. Milling to produce flour for human
consumption also includes the preliminary steps of wheat cleaning and
conditioning (tempering).

© Woodhead Publishing Limited, 2013