Number 229 Breadmaking Improving quality Second edition Edited by Stanley P... Woodhead Publishing Series in Food Science, Technology and Nutrition 1 Chilled foods: a comprehensive g
Trang 3Cereal grains
(ISBN 978-1-84569-563-7)
The quality of cereal products is dependent to a large extent on the suitability of the cereal grains processed Therefore it is essential that cereals producers and handlers understand grain quality requirements for different end uses Grain suppliers and users must also be able to rapidly and accurately assess grain end-use quality and use this information to direct their grain quality management activities This book provides a convenient and comprehensive overview of academic research and industry best practice in these areas Chapters review quality aspects of different cereals and also specifi c aspects of grain quality analysis and management
Technology of functional cereal products
different health-promoting properties and more acceptable sensory quality
Introductory chapters summarise the health effects of whole grains and cereal components such as resistant starch The second part of the book focuses on
technologies to improve the quality of a wide range of cereal products, such as fortifi ed breads, pasta and products made from non-wheat grains such as oats and rye Details of these books and a complete list of Woodhead’s titles can be obtained by:
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Trang 4Number 229
Breadmaking
Improving quality Second edition Edited by Stanley P Cauvain
Trang 580 High Street, Sawston, Cambridge CB22 3HJ, UK
www.woodheadpublishing.com
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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
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Library of Congress Control Number: 2012931170
ISBN 978-0-85709-060-7 (print)
ISBN 978-0-85709-569-5 (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
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Trang 6Contents
Contributor contact details xv
Woodhead Publishing Series in Food Science, Technology and Nutrition xxi
1 Introduction to breadmaking 1
S Cauvain, BakeTran, UK 1.1 Introduction 1
1.2 Wheat and its special properties 2
1.3 Converting wheat to fl our 3
1.4 Food safety and nutrition 4
1.5 Making bread 5
1.6 Functional ingredients 6
1.7 Bread in the future 7
1.8 References 8
2 Breadmaking: an overview 9
S Cauvain, BakeTran, UK 2.1 Introduction 9
2.2 Bread dough development 11
2.3 Breadmaking processes 12
2.4 What determines bread quality? 15
2.5 Dough mixing and processing 19
2.6 Cell creation during mixing 21
2.7 Dough processing 22
2.8 Gas bubble control during dough processing 25
2.9 Proving and baking 26
2.10 Future trends 28
2.11 Sources of further information and advice 29
2.12 References 29
Trang 7Part I Wheat and fl our quality 33
3 The chemistry and biochemistry of wheat 35
H J Cornell, RMIT University, Australia 3.1 The structure and composition of the wheat kernel 35
3.2 Wheat carbohydrates 42
3.3 Wheat proteins 51
3.4 Wheat lipids 64
3.5 Wheat enzymes and their roles 66
3.6 Pigments and their structures 68
3.7 Recent developments in wheat utilisation 68
3.8 Future trends 70
3.9 Sources of further information and advice 70
3.10 References 72
4 Techniques for analysing wheat proteins 77
A M Gil, University of Aveiro, Portugal 4.1 Introduction 77
4.2 Separation methods 78
4.3 Analysing molecular properties 80
4.4 Rheological measurements 81
4.5 Infrared spectroscopy 83
4.6 NMR spectroscopy 85
4.7 Electron spin resonance spectroscopy 91
4.8 Future trends 93
4.9 Acknowledgements 95
4.10 References 95
5 Wheat proteins and bread quality 100
E N Clare Mills, N Wellner, L A Salt, J Robertson and J A Jenkins, Institute of Food Research, UK 5.1 Introduction: cereal protein classifi cation 100
5.2 Cereal proteins and breadmaking quality 107
5.3 Prolamin structure and bread quality 108
5.4 Soluble proteins, xylanase inhibitors and bread quality 111
5.5 Detergent-solubilised proteins and bread quality 113
5.6 Genomics and the wheat grain proteome 115
5.7 Conclusion and future trends 117
5.8 Acknowledgements 118
5.9 References 118
6 Wheat starch structure and bread quality 123
A.-C Eliasson, Lund University, Sweden 6.1 Introduction: the importance of starch structure to bread quality 123
Trang 86.2 Starch properties and baking performance 124
6.3 Physico-chemical properties of starch in relation to the baking process 131
6.4 Starch structure and chemical composition 134
6.5 Future trends 140
6.6 Sources of further information and advice 141
6.7 References 141
7 Assessing grain quality 149
C W Wrigley, Wrigley Consulting, Sydney, Australia and I L Batey, Sunset Consulting, Sydney, Australia 7.1 Introduction 149
7.2 The importance of quality assessment at harvest 151
7.3 The grain chain 154
7.4 Analysis during breeding to achieve quality targets 156
7.5 Analysis on-farm to achieve quality targets 158
7.6 Sampling aims and methods 161
7.7 Analysis at grain receival to achieve quality targets 165
7.8 Analysis during storage and transport to achieve quality targets 177
7.9 Analysis in buying and blending to achieve fl our-quality targets 178
7.10 Future trends 179
7.11 Sources of further information and advice 181
7.12 References 181
8 Milling and fl our quality 188
G M Campbell, C Webb and G W Owens, Satake Centre for Grain Process Engineering, University of Manchester, UK and M G Scanlon, University of Manitoba, Canada 8.1 Introduction 188
8.2 Flour milling 189
8.3 Recent developments in fl our milling 196
8.4 Flour milling and fl our quality 201
8.5 Milling research 206
8.6 The future of fl our milling 212
8.7 Conclusion 213
8.8 Acknowledgements 213
8.9 References 214
9 Wheat breeding and quality evaluation in the US 216
M Tilley and Y R Chen, Center for Grain and Animal Health Research, USA and R A Miller, Kansas State University, USA 9.1 Introduction 216
9.2 Wheat classifi cation 218
Trang 99.3 Selection of wheat varieties with desired characteristics 221
9.4 Future trends 233
9.5 Sources of further information and advice 234
9.6 References 235
10 Improving wheat protein quality for breadmaking: the role of biotechnology 237
P R Shewry and H D Jones, Rothamsted Research, UK 10.1 Introduction 237
10.2 Wheat gluten proteins and dough strength 238
10.3 High molecular weight (HMW) subunits and bread quality 240
10.4 The genetic transformation of wheat 244
10.5 Manipulating HMW subunit composition and dough properties 246
10.6 Prospects for using genetic modifi cation (GM) to improve wheat processing quality 251
10.7 Sources of further information and advice 252
10.8 Acknowledgements 252
10.9 References 253
11 Novel approaches to modifying wheat fl our processing characteristics and health attributes: from genetics to food technology 259
S Islam, W Ma, G Yan, F Bekes and R Appels, CSIRO Plant Industry, Australia 11.1 Introduction 259
11.2 Exploiting natural variation in gluten proteins to modify wheat quality 261
11.3 The genetic modifi cation of wheat 266
11.4 Use of non-wheat fl ours to modify bread quality attributes 268
11.5 Modifi cations to reduce wheat allergy and intolerance 274
11.6 Conclusions 282
11.7 References 284
Part II Dough development and particular bread ingredients 297
12 Bread aeration and dough rheology: an introduction 299
G M Campbell and P J Martin, Satake Centre for Grain Process Engineering, University of Manchester, UK 12.1 Introduction: the appeal of raised bread and the unique rheology of wheat fl our doughs 299
12.2 The history of bread aeration studies 301
12.3 The history of dough rheology studies 303
12.4 Methods for studying bread aeration and dough rheology 308
Trang 1012.5 Breadmaking – a series of aeration/rheology interactions 314
12.6 The future of bread aeration and rheology research 325
12.7 Conclusions 325
12.8 Acknowledgements 327
12.9 Further reading 328
12.10 References 329
13 The molecular basis of bread dough rheology 337
P S Belton, University of East Anglia, UK 13.1 Introduction 337
13.2 Factors affecting dough rheology 338
13.3 Polymer networks in doughs 341
13.4 The molecular mechanism of energy storage in dough 344
13.5 How much dough rheology can we explain? 347
13.6 Future trends 348
13.7 Sources of further information and advice 349
13.8 References 349
14 The role of water in dough formation and bread quality 352
A Schiraldi and D Fessas, University of Milan, Italy 14.1 Introduction 352
14.2 Dough as a dispersed system 354
14.3 Water displacements and time-dependent properties of the dough 359
14.4 Future trends 365
14.5 Sources of further information and advice 366
14.6 References 366
15 Foam formation in dough and bread quality 370
P Wilde, Institute of Food Research, Norwich, UK 15.1 Introduction 370
15.2 Principles of foam formation and stability 371
15.3 Surface-active dough components 377
15.4 The role of the aqueous phase of dough 379
15.5 Analytical techniques 389
15.6 Future trends 393
15.7 Sources of further information and advice 394
15.8 References 394
16 Controlling bread dough development 400
S Millar and G Tucker, Campden BRI, UK 16.1 Introduction 400
16.2 Dough rheology during mixing 401
16.3 Dough development 403
16.4 Oxidising and reducing agents 407
Trang 1116.5 The effects of mixer type 408
16.6 The Radical Bread Process 411
16.7 Controlling dough development 414
16.8 Emerging methods for controlling dough development 419
16.9 Future trends 424
16.10 Sources of further information and advice 425
16.11 References 426
17 Molecular mobility in dough and bread quality 430
Y H Roos, University College Cork, Ireland 17.1 Introduction 430
17.2 Molecular mobility in dough 431
17.3 Dough properties in baking 437
17.4 Controlling molecular mobility to improve bread quality 439
17.5 Future trends 442
17.6 Sources of further information and advice 443
17.7 References 443
18 The use of redox agents in breadmaking 447
H Wieser, German Research Centre of Food Chemistry, Germany 18.1 Introduction 447
18.2 The redox state in fl our 448
18.3 Redox reactions during processing 454
18.4 Redox agents: oxidants and reductants 458
18.5 Future trends 465
18.6 Sources of further information and advice 466
18.7 References 466
19 Applications of enzymes in breadmaking 470
B A Kornbrust, Novozymes Switzerland AG, Switzerland, T Forman, Novozymes North America Inc., USA and I Matveeva, Novozymes A/S Russia, Russian Federation 19.1 Introduction 470
19.2 The nature of enzymes 471
19.3 The commercial production of enzymes 474
19.4 Genetically modifi ed organism (GMO) 476
19.5 Applications in breadmaking 476
19.6 Baking examples 488
19.7 Future trends 493
19.8 Sources of further information and advice 493
19.9 Acknowledgements 494
19.10 References 494
20 Water control in breadmaking 499
S P Cauvain and L S Young, BakeTran, UK 20.1 Introduction: water composition and properties 499
Trang 1220.2 Water in breadmaking 502
20.3 Dough formation 505
20.4 Proving and baking 510
20.5 Water activity after baking 514
20.6 Future trends 518
20.7 Sources of further information and advice 518
20.8 References 518
Part III Bread sensory quality, shelf life and safety 521
21 Bread aroma 523
C Prost, P Poinot, C Rannou and G Arvisenet, LUNAM Université, Oniris, France 21.1 Introduction 523
21.2 The formation of volatile compounds during breadmaking 524
21.3 Extraction and analysis of bread volatile compounds 532
21.4 Volatile composition of bread 538
21.5 How can bread aroma be improved? 552
21.6 Conclusion 555
21.7 Acknowledgements 555
21.8 References 555
22 Applications of texture analysis to dough and bread 562
L S Young, BakeTran, UK 22.1 Introduction 562
22.2 Principles and types of instrumental analysis as applied to dough 564
22.3 Principles and types of instrumental analysis as applied to bread 571
22.4 Future trends 578
22.5 Sources of further information and advice 578
22.6 References 578
23 Bread staling 580
P Rayas-Duarte, Oklahoma State University, USA and S Mulvaney, Cornell University, USA 23.1 Introduction 580
23.2 Breadcrumb structure 581
23.3 Bread stability 581
23.4 Anti-staling agents 591
23.5 Future trends 592
23.6 References 594
Trang 1324 Mould prevention in bread 597
N Magan, D Aldred and M Arroyo, Cranfi eld University, UK 24.1 Introduction: the problem of moulds in bread 597
24.2 Current techniques for mould control and their limitations 599
24.3 Developing new methods for mould control 604
24.4 Future trends 610
24.5 Sources of further information and advice 611
24.6 References 611
25 Mycotoxin contamination of wheat, fl our and bread 614
W J de Koe, Life- and Food-Science Consultant, The Netherlands and G Juodeikiene, Kaunas University of Technology, Lithuania 25.1 Introduction: mycotoxin contamination of foods 614
25.2 Some persistent problems associated with the presence of mycotoxins in the food chain 618
25.3 Parent mycotoxins in cereals occurring in bread and bakery products 621
25.4 Legislation 631
25.5 Developments in analytical techniques 637
25.6 The development of non-invasive and rapid (screening) techniques 644
25.7 Future trends 646
25.8 Sources of further information and advice 650
25.9 References 650
Part IV Particular bread products 659
26 Improving the quality of bread made from partially baked, refrigerated and frozen dough 661
A Le-Bail, LUNAM Université, Oniris, France and D Gabric, Zagreb University, Croatia 26.1 Introduction 661
26.2 Frozen part-baked technology 664
26.3 Non-fermented frozen dough technology 671
26.4 Pre-fermented frozen dough technology 676
26.5 Energy demand for the bake-off technologies 679
26.6 Conclusions 680
26.7 References 681
27 Nutritionally enhanced wheat fl ours and breads 687
C M Rosell, Institute of Agrochemistry and Food Technology (IATA-CSIC), Spain 27.1 Introduction 687
Trang 1427.2 The nutritional value of wheat 689
27.3 The effect of processing on the nutritrional value of wheat 690
27.4 Different approaches to increase the nutritional value of wheat fl our 692
27.5 Nutritional improvement of wheat fl ours during breadmaking 698
27.6 Ingredients for enriching wheat-baked goods 700
27.7 Conclusions 705
27.8 Sources of further information and advice 706
27.9 References 706
28 Formulating breads for specifi c dietary requirements 711
A.-S Hager, E Zannini and E K Arendt, University College Cork, Ireland 28.1 Introduction 711
28.2 Wheat allergy and coeliac disease 712
28.3 Glycaemic index and glyacemic load 721
28.4 Bread high in dietary fi bre 723
28.5 Future trends 727
28.6 Sources of further information and advice 728
28.7 References 728
29 Improving the quality of high-fi bre breads 736
K Hartikainen and K Katina, VTT, Finland 29.1 Introduction 736
29.2 Sources of fi bre 737
29.3 Challenges in high-fi bre baking 741
29.4 Improving the quality of fi bre-enriched foods 744
29.5 Future trends 749
29.6 References 750
30 The quality of breads made with non-wheat fl ours 754
K G Duodu and J R N Taylor, University of Pretoria, South Africa 30.1 Introduction 754
30.2 Non-wheat pan breads 755
30.3 Traditional non-wheat bread products 761
30.4 Quality issues 769
30.5 Future trends 776
30.6 References 778
Index 783
Trang 16Contributor contact details
E-mail: agil@ua.pt
Chapter 5
E N Clare Mills*, N Wellner,
L A Salt, J Robertson and J A Jenkins
Institute of Food Research Norwich Research Centre Colney
Norwich NR4 7UA
UK E-mail: clare.mills@bbsrc.ac.uk
Chapter 6
A.-C Eliasson Department of Food Technology, Engineering and Nutrition Lund University
P.O Box 124 S-221 00 Lund Sweden E-mail: Ann-Charlotte.Eliasson@food.lth.se
Trang 17School of Chemical Engineering
and Analytical Science
1515 College Avenue Manhattan
KS 66502 USA E-mail: michael.tilley@ars.usda.gov
R A Miller Wheat Quality Laboratory Department of Grain Science and Industry
Kansas State University Manhattan
KS USA
Chapter 10
P R Shewry* and H D Jones Rothamsted Research
Harpenden AL5 2JQ
UK E-mail: peter.shewry@rothamsted.ac.uk ; huw.jones@rothamsted.ac.uk
Chapter 11
S Islam, W Ma, G Yan, F Bekes and
R Appels*
Department of Agriculture Centre for Comparative Genomics Murdoch University
Bentley Delivery Centre WA6983
Australia E-mail: rappels@ccg.murdoch.edu.au
Trang 18
Chapter 12
G M Campbell* and P J Martin
Satake Centre for Grain Process
A Schiraldi* and D Fessas
DISTAM, sez Chimica
Institute of Food Research
Norwich Research Park
Colney
Norwich
NR4 7UA
UK E-mail: peter.wilde@ifr.ac.uk
Chapter 16
S Millar and G Tucker*
Campden BRI Chipping CampdenGloucester
GL55 6LD
UK E-mail: s.millar@campden.co.uk ; g.tucker@campden.co.uk
Chapter 17
Y H Roos University College Cork Cork
Ireland E-mail: yrjo.roos@ucc.ie
Chapter 18
H Wieser German Research Centre of Food Chemistry
Garching Germany E-mail: H.Wieser@lrz.tu-muenchen.de
Chapter 19
B A Kornbrust*
Novozymes Switzerland AG Neumatt
4243 Dittingen Switzerland E-mail: bkor@novozymes.com
Trang 19Novozymes A/S Russia
Moscow Representative Offi ce
L S Young BakeTran
UK E-mail: spc@baketran.demon.co.uk
Chapter 23
S Mulvaney Department of Food Science Cornell University
Ithaca
NY 14853 USA E-mail: sjm7@cornell.edu
Chapter 24
N Magan*, D Aldred and M Arroyo Applied Mycology Group
Cranfi eld Health Cranfi eld University MK43 0AL
UK E-mail: n.magan@cranfi eld.ac.uk
Chapter 25
W J de Koe*
Prof Van Uvenweg 161
Trang 206708 AH Wageningen
The Netherlands
E-mail: wjdekoe@super.lt
G Juodeikiene
Department of Food Technology
Faculty of Chemical Technology
Kaunas University of Technology
Department of Food Science
Institute of Agrochemistry and Food
Technology (IATA-CSIC) Avda Catedrático Agustín Escardino, 7 Paterna – 46980
Spain E-mail: crosell@iata.csic.es
Chapter 29
K Hartikainen and K Katina* VTT
Tietotie 2 Espoo P.O Box 1000 FIN 02044 VTT Finland
E-mail: kati.katina@vtt.fi
Chapter 30
K G Duodu* and J R N Taylor Department of Food Science University of Pretoria Pretoria 0002
South Africa E-mail: gyebi.duodu@up.ac.za
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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
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
Trang 26133 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 fl avour 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 fl avour 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 fi elds: 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 fl avour: recent advances and future prospects Edited by
B Brückner and S G Wyllie
156 Food fortifi cation 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
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 fi sh 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
Trang 27167 Shellfi sh 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 fi lled 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 effi ciency, 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 Biofi lms 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
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 Griffi ths
189 Improving the safety and quality of milk Volume 2: improving quality in milk
products Edited by M Griffi ths
190 Cereal grains: assessing and managing quality Edited by C Wrigley and
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
Trang 28197 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
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
Trang 29223 Lifetime nutritional infl uences on cognition, behaviour and psychiatric illness
226 Extrusion problems solved: food, pet food and feed M N Riaz and G J Rokey
227 Handbook of herbs and spices Volume 1 Second edition Edited by K V Peter
228 Handbook of herbs and spices Volume 2 Second edition 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 infl ammation Edited by P C Calder and P Yaqoob
233 Natural food additives, ingredients and fl avourings Edited by D Baines and
R Seal
234 Food decontamination: novel methods and applications Edited by A Demirci and
M Ngadi
235 Chemical contaminants and residues in foods Edited by D Schrenk
236 Robotics and automation in the food industry: current and future technologies
239 Encapsulation technologies and delivery systems for food ingredients and
nutraceuticals Edited by N Garti and D J McClements
Trang 301
Introduction to breadmaking
S Cauvain, BakeTran, UK
Abstract: The nature of bread quality is discussed and the relevance of the various
chapters that follow to improving bread quality introduced The essential nature of gluten and its development in breadmaking is considered along with aspects of food safety and nutrition The underpinning processes that contribute to current and future bread qualities are highlighted
Key words: quality, food safety, nutrition, processing
1.1 Introduction
Mention the word ‘quality’ and on a good day my eyes normally glaze over as pictures of detailed and often meaningless ‘procedures’ apparently designed to ensure the quality of a process or a product spring to mind On a bad day I might run screaming from the room The big problem with most ‘quality systems’ is that they fail to take suffi cient account of the ‘real’ purpose of the procedure or product concerned This is especially the case in breadmaking where the perception of product quality is very personal We all have our selection of criteria that classify bread as ‘good’ or ‘bad’, ‘correct’ or ‘wrong’ and while there are some common characteristics on which many of us would agree (for example, the bread should not be mouldy at the time of consumption) the fi nal judgement of what is the right quality will always be highly personal I am known for answering the question from bakers as to what is the ‘right’ quality along the lines of ‘Whatever product quality you can make consistently that brings customers back time after time, and which you can make money producing’
In the fi nal analysis if we defi ne quality as being ‘fi tness for purpose’ then for each of us the bread quality may be described as being the sum of those quality traits that confer the sensory pleasures associated with smell, taste and texture In summary, when we taste and eat the product we experience pleasure Our
Trang 31individual perception will then depend on the combination of those parameters that characterise the mix of product appearance, texture, smell and fl avour which best suits each of us and have become part of our subconscious perception of bread quality We must also recognise that our perception of quality will change with the passage of time and personal circumstances, not least our individual health
While there are many factors which characterise the quality of bread products that can be easily defi ned and measured, e.g loaf height and volume, there are many others which are ephemeral in nature and therefore more diffi cult to defi ne, e.g smell and fl avour In defi ning quality, the term ‘consistency’ is often used as frequently as fi tness for purpose Consistency is indeed a desirable quality trait with most products but for the highly individual perception of bread quality even this ‘simple’ quality trait is diffi cult to apply with absolute certainty If you are a sandwich maker then you certainly want consistency of volume, shape and cell structure but in a craft bakery context, customers may still want to choose between light and dark crust coloured products The variability in bread qualities sought by consumers demands that bakers be able to meet all of the quality requirements concerned All in all, breadmaking requires a deep understanding of the many complex raw material and process interactions that collectively contribute to fi nal product quality and it is the skills of bakers which ensure that the required qualities are delivered to consumers
1.2 Wheat and its special properties
Almost every discussion of bread and its quality will start with a reference to the special nature of wheat, and given that wheat fl our is the largest ingredient in dough and bread formulations, this is hardly surprising In the contributions that follow, much will be made of the special properties of wheat fl our proteins to form gluten after hydration and during mixing, whether that mixing is delivered mechanically or by hand Dough mixing is the process that starts dough aeration
as the gluten forms a network which traps and retains bubbles of air for infl ation
by carbon dioxide gas from yeast fermentation or in more ‘natural’ processes from lactic acid and other types of bacteria It is because of the special properties of wheat proteins that much research has been devoted to them Chapter 3 provides
a comprehensive insight to the many different aspects of wheat chemistry and biochemistry and this theme is continued in Chapters 5 , 6 and 4 Improvements in wheat quality to make it better suited to its end uses are considered in Chapters 9 and 10 , along with opportunities for future development The key role of gluten-forming proteins rightly receives considerable attention in several chapters but to address the balance, the role of wheat starch is considered in Chapter 6
Fundamental to achieving a given bread quality is the ability to measure wheat quality and predict the likely breadmaking performance of any given wheat sample (Cauvain and Young, 2009) This has been the ‘holy grail’ for farmers, millers and bakers for centuries Cereal science has developed many techniques
Trang 32and tools to help, but the complexity of those little wheat grains and the impact of farming practices on grain quality means that the goal still remains largely unattained Much progress has been made and is considered in several of the chapters that follow However, if you read on expecting to encounter a single test for making the perfect prediction you will be disappointed It remains unlikely that there will be a single test (other than baking) that will predict bread quality with certainty The many different types of bread and breadmaking processes, each requiring a degree of variation in the ‘quality’ predictors, reduce the likelihood of achieving a single quality test For the moment we will have to content ourselves with using a range of analytical techniques and a number of these are addressed in the chapters of this book, which may help you decide which combination best suits your particular needs
1.3 Converting wheat to fl our
In order to make an aerated bread structure it is necessary to process the wheat grains into another, more suitable form Over the centuries techniques have evolved that permit the separation of the white endosperm from the darker-coloured bran skins and germ The progression towards greater availability of white fl our has spawned the large number of bread products that we see in bakeries today A number of factors have driven the move to white fl ours, not least the greater gluten forming potential of the wheat proteins in the starchy endosperm
As discussed in Chapter 8 the fl our milling process has evolved into a sophisticated process but its effi ciency and economic viability still depend on the quality of the raw material entering the fl our mill Because of this fl our millers remain acutely aware of the need to assess wheat quality and link its qualities with the fi nal product for which it is destined Flour millers therefore continue to use a range of tests to assess both the reliability and consistency of their own operations (Cauvain and Young, 2009)
It is perhaps worth a comment on the subject of fl our specifi cations Too often the baker has diffi culty in relating fl our specifi cations to fl our performance in bread baking The key requirement is that the fl our which bakers use should make the product that bakers (and their customers) require The fl our specifi cation may well be the basis for confi dence that the fl our will deliver the required end product, however, it should be noted that since there is no defi nitive means of predicting the performance of a given fl our in a given baking process, then the main purpose
of measuring fl our characteristics on a regular basis is to assess whether the fl our meets the original specifi cation In other words the specifi cation is about whether the fl our is the same as delivered on previous occasions and as such is only an indication that it will make the end product required Flour quality checks should only be seen as ‘ticking the required quality boxes’ It is essential that when bakers
choose fl ours for production then they specify what they need : this is not always
an easy task but the risks associated with inappropriate choices can be very costly
in production terms
Trang 331.4 Food safety and nutrition
Cereals and cereal-based products are amongst the safest of foods that we have available However, growing and processing grain is not without its hazards Some of the most deadly toxins are those which occur naturally In cereals such unwanted materials may come in the form of mycotoxins With the widespread transport and longer-term storage of cereal products, issues of food safety have become increasingly important and for these reasons the detection and control of mycotoxins materials are the subject of Chapter 25
Bread and other fermented products have remained a staple food for thousands
of years In the past the key role for bread was the simple provision of energy, but
in more recent years the role that wheat-based products play in delivering additional nutritional benefi ts has become more prominent Such benefi ts include the provision of fi bre and essential nutrients beyond the simple value of protein and carbohydrate Wheat-based products have been and are still seen as potential vehicles for delivering addition nutritional value through fortifi cation because of the signifi cant contribution that wheat-based products make to many diets around the world Fortifi cation has commonly been practised using calcium, iron and some vitamins but to this list in recent times we should add folic acid Food fortifi cation is not without its critics and is not universally practised, nevertheless the ubiquitous nature of wheat-based products does offer a ready vehicle for delivering improved nutrition to many parts of the world
Since nutritional properties are not homogeneously distributed throughout the wheat grain, separating the endosperm from the other components to yield white
fl our is not without its penalties In those circumstances where nutrition is at a premium the fortifi cation of fl our- and wheat-based products has become a political and humanitarian issue The role of fortifi cation and the means by which
it may be achieved are discussed in Chapter 27 , and they provide an insight to another important aspect of bread quality
The nutritional–quality link is also covered in Chapter 29 where the role of increasing fi bre levels in bread is discussed In many parts of the world previous approaches to breadmaking had become dominated by white fl our-based products but now there is a greater use of higher extraction fl ours and combinations of wheat fl ours with other grains and seeds The conversion of all wheat grains to
fl our has always been with us but the quality attributes of wholemeal or wholewheat bread have not had suffi cient appeal for the mass market In the UK when the technology developed for making wholemeal and similar breads as large and similar in softness to white breads sales rose from 2 to 20% of breads sold In recent years there has been a small decrease in non-white bread production and consumption but levels remain higher than 25 years ago The increase in sales was truly product quality-driven, since the fi bre hypothesis had been around for quite some years with little impact on the dietary habits of the average UK consumer
As special as wheat and wheat-based products may be there are some communities which cannot tolerate the proteins that are present in wheat and some other grains The prevalence of coeliac disease and wheat intolerances are
Trang 34the subject of much new research and the need to develop suitable products is highlighted in Chapter 28
1.5 Making bread
Breadmaking is a centuries-old traditional craft, practised in any country capable
of growing or importing wheat This has meant the evolution of a diverse range of breadmaking processes designed to achieve a wide range of bread products There are a number of central themes that are common to all bread products and breadmaking processes They are: the mixing of wheat fl our, water, yeast and other functional ingredients and the expansion of the dough mass through the generation of carbon dioxide gas
In Technology of Breadmaking (Cauvain and Young, 2002, 2007) it has been
stated of no-time dough-making processes that ‘About 90% of fi nal bread quality
is decided by what bakers chose to do in the mixer’ This aspect of quality embraces the choice of raw materials and formulation as well as decisions on how
to mix and develop the gluten structure in the dough The relationship between mixing and dough development is still not fully understood This theme is visited
in many of the chapters in this book It is well known that simply blending the bread recipe ingredients is not enough to initiate the development of the gluten structure The technological aspects associated with gluten development and their place in the different breadmaking processes are discussed in Chapters 2 and 12
If you want convincing of the relative importance of mixing and dough development, try mixing your own bread dough by hand The harder you work the dough (that is the more energy you put into the mixing/development process), the greater will be the gas retention in the dough, the larger the loaf and the softer its crumb However, the mixing times concerned may last for 30 minutes so be prepared for some hard work and a signifi cant rise in your personal temperature which confi rms the fundamental relationship between work (energy) and heat! In-depth considerations of the molecular changes during dough mixing will be encountered in several chapters The molecular interactions involved depend very signifi cantly on the key quality traits of the proteins in wheat, and as discussed in Chapters 13 and 15 we can see how the genetic puzzle that is wheat protein is slowly being solved The role of water in gluten development is commonly taken for granted with water being seen simply as an ingredient that varies in level of addition with fl our properties so that bakers can achieve a given consistency It is true that the quantity of water added to bread fl our is critical in providing a dough rheology which is suitable for subsequent processing but as discussed in Chapters 14 and 16
it is also part of the underpinning essential molecular changes which occur during the mixing/development process Experiments with powdered ice or pre-hydrated
fl ours reveal the complex relationship between hydration and development Water plays a key role all through the breadmaking process starting with mixing and ending with contributions to end product eating and keeping quality These pivotal roles are described in Chapter 20 Critical reference to dough rheology, its control
Trang 35and contribution to fi nal product quality is made in many chapters Techniques for assessing dough rheology have changed (Cauvain and Young, 2009), and some of the latest developments are described in discussions that follow
There was a time when many bakers considered water to be a ‘free’ ingredient
or at least a cheap one Those days have gone and the only truly cheap ingredient left for the baker is air It is ironic that a plentiful, cheap ingredient plays such a key role in the breadmaking processes The role of air assumes equal importance with that of wheat fl our, water and yeast It has been said that gases are the neglected ingredients in breadmaking but after reading Chapter 12 you would be forgiven for thinking that this is far from true The study of the contribution of gases goes back over 70 years and the latest research is providing a fascinating insight into the role of gas bubbles in bread doughs and how they change during breadmaking Gases may well have been taken for granted and overlooked by the baker but that is certainly not the case for the cereal scientist
The concept of bread fl avour is perhaps the most contentious of all the quality issues associated with bread The formation of bread fl avour arises in part from fermentation processes and in part from the complex interactions between the heat of the oven and the recipe ingredients Factors that infl uence bread aroma are discussed in Chapter 21 , and readers are left to form their own opinions on this highly individual subject
1.6 Functional ingredients
An alternative term for functional ingredients in common usage is ‘improvers’ Every ingredient used in breadmaking has a function and in the alternative sense
‘improves’ bread quality An ‘improving’ effect could be put forward for the use
of yeast added to fl our and water to produce leavened rather than unleavened bread On the one hand an ‘improving’ effect can be claimed for salt additions (sodium chloride) which contribute to control of gluten rheology and yeast fermentation, but a counter argument would certainly be put by advocates for lower salt levels in bread and the diet as a whole for medical reasons
The foregoing comments show the ambiguous position that functional ingredients (improvers) hold in the psychology of breadmaking While purists may argue for ‘no artifi cial additives’ and ‘clean label’ (whatever these descriptors mean), the demands of the modern consumer for consistent quality and safe food continue to make a strong case for additions of functional ingredients Loss of bread quality is commonly associated with microbial spoilage as discussed in Chapter 24 Consumer shopping patterns in many parts of the world have changed such that the daily trip to the bakery is not the norm and such consumers expect that bread products remain spoilage free for signifi cant periods since they have no desire to throw away uneaten product Given these constraints it is not surprising that bakers have turned to the use of preservatives to limit microbial growth
‘Natural’ anti-microbial agents may become more readily available as scientifi c studies continue
Trang 36From the moment that bread leaves the oven its qualities begin to change This
is the ‘staling’ process Bread staling is most commonly associated with the progressive fi rming of the crumb, with or without moisture loss This is the process discussed in Chapter 23 Again consumer expectations are high and they see fi rming of the crumb as unacceptable in quality terms Bakers have evolved strategies to limit the changes through the additions of functional ingredients such
as emulsifi ers and enzymes The purists may see this view as supporting unacceptable practices Changes in crust characteristics may also be seen as part
of the staling process and loss of quality The use of par-baked products has increased (see Chapter 26 ) and limiting staling plays a key role in delivering acceptable products of this kind
Modern no-time dough making processes of the type described in Chapter 2 make use of mechanical development of gluten structures in the presence of oxidising agents As concerns over food safely increase (rightly so) the list of permitted oxidants has shrunk in many parts of the world to ascorbic acid only Nevertheless there are countries (e.g the USA) which permit a wider range of oxidising agent additions and their roles are discussed in Chapter 18 While one may argue that such ingredients are unacceptable, the baker is faced with the demand for consistent quality and so ingredients like ascorbic acid continue to
fi nd a place in modern breadmaking
1.7 Bread in the future
Bread has a long history and undoubtedly has a long future It is hard to imagine
a world evolving in which bread in some form does not play a part as a food source However, this does not mean that bread products themselves will not change The history of breadmaking is one of continuous product development and process innovation For many years the pace of development was slow but in the twentieth century improved communication and wider travel opportunities have exposed the majority of consumers to a wider range of food experiences than those of the previous centuries would have enjoyed
A wider variety of breads will continue to be available for the ‘average’ consumer Whether this will arise because of consumer demands or marketers’ push would be an interesting debate Bread ‘price wars’ are all too common in some parts of the world and they devalue the standing of this noble product but at the same time we must recognise that they also provide the drive for product and process innovation Consumers may want different products for their table but consistent quality remains a pre-requisite This is not to argue that all breads must
be based on modern processes Quite the reverse, ‘traditional’ products will remain in demand because they add to the range of available bread varieties Today even the word ‘traditional’ when applied to bread has begun to take on
a new meaning, especially in the UK When I joined the UK cereals industry the Chorleywood Bread Process (CBP) was relatively new and facing the hostility of
‘traditional’ craft (artisan) bakers Ironically the CBP was originally developed for
Trang 37the craft baker but the economic and consistent quality arguments for its use were quickly identifi ed by the larger plant bakeries It is with plant-produced bread that CBP has mostly been associated Like them or not, the innovations in breadmaking which occurred during the 1960s were a watershed for the cereals industry, the legacy of which we continue to employ today It is over 50 years since the launch
of the CBP (Cauvain and Young, 2006) and in the UK the Food Standards Agency has come to the (perhaps unpalatable for some) conclusion that the term
‘traditional’ may be applied to bread made by the CBP Surely that conclusion is only fair, given that we now have whole generations of bakers who have grown up knowing little other than no-time dough-making processes like the CBP
So where will breadmaking go in the future? The future of breadmaking remains essentially sound, wheat-based products will certainly remain part of diets around the world Whether we are discussing no-time dough or long fermentation-based processes, there will be challenges Key ones will continue to deliver nutritious and palatable products as pressure on food, energy and water resources grows against a background of potential climate change
The answers to future breadmaking problems will come from two sources The
fi rst is from the authors of the different chapters in this book, who have identifi ed their own views of the past, present and future prospects for their own specialist area I wish to personally thank each of them for their time and efforts, whether in writing new or revising earlier chapters Writing a book chapter is seldom easy and trying to second-guess where the cereals industry will go in the future needs
a very special type of crystal ball
The second source of inspiration for future developments and innovation in breadmaking is from you, the reader Hopefully each chapter of this book will provide you with inspiration and encouragement to make your own personal contribution to making bread of the ‘right’ quality for consumers of the future
I hope that you enjoy reading the book
CAUVAIN , S P and YOUNG , L S ( 2007 ) Technology of Breadmaking , 2nd edn , Springer
Science & Business Media, LLC , NY
CAUVAIN , S P and YOUNG , L S ( 2009 ) The ICC Handbook of Cereals, Flour, Dough and
Product Testing: Methods and Applications DES tech Publications, Inc , Lancaster, PA
Trang 382
Breadmaking: an overview
S Cauvain, BakeTran, UK
Abstract: The nature of bread quality and the contribution of the key ingredients are
discussed The principles of the main bread making processes and their relationship with
fi nal bread quality are described The processing of the bulk dough from the mixer through to baked loaf and the contribution that the individual stages make to fi nal product quality are considered
Key words: mixing, dough development, CBP, sponge and dough, no-time dough, dough
processing, proving, baking, foam to sponge conversion
2.1 Introduction
Bread is a staple foodstuff, which is made and eaten in most countries around the world Bread products have evolved to take many forms, each based on quite different and distinctive characteristics Over the centuries craft bakers have developed our traditional bread varieties using their accumulated knowledge as to how to make best use of their available raw materials (particularly the wheat) to achieve the desired bread quality In some countries the nature of breadmaking has retained its traditional form while in others it has changed dramatically In many cases the changes have occurred when access has been gained to new, often imported, wheat varieties The globalisation of wheat trading was probably the
fi rst step in the globalisation of baking
The proliferation of bread varieties derives from the unique properties of wheat proteins to form gluten and from the bakers’ ingenuity in manipulating the gluten structures formed within the dough The rubbery mass of gluten with its ability to deform, stretch, recover shape and trap gases is very important in the production
of bread and all fermented products Of all the cereals, wheat is almost unique in this respect The term ‘bread’ is used to describe such a wide range of products with different shapes, sizes, textures, crusts, colours, softness, eating qualities and
Trang 39fl avours that the terms ‘good’ or ‘bad’ quality tend to have no real meaning, except
to the individual making the assessment A baguette is not a baguette without a crisp crust, while the same crust formation would be unacceptable on north American pan bread and the fi ne cell structure of sandwich bread in the UK has
no relevance to the fl at breads of the Middle East
The character of bread and other fermented products depends heavily on the formation of a gluten network (the foam) which traps gas from yeast fermentation and makes a direct contribution to the formation of a cellular crumb structure (the sponge) which, after baking, confers texture and eating qualities quite different from other baked products Look closely at the crumb structures of most baked breads and you will see that the common linking theme is that they are formed of holes of differing shapes, sizes and distributions Each hole is embraced by a network of connected strands, coagulated gluten, in which starch granules and bran particles are fi rmly embedded When this crumb is subjected to pressure with the fi ngers it deforms, and when the force is removed it springs back to assume more or less its original shape, at least when the product is fresh This combination
of a cellular crumb with the ability to recover after being compressed largely distinguishes breads from other baked products: these are the very characteristics that bakers seek to achieve in most bread products While there are many different breadmaking processes, they have the common aim of converting wheat fl our and other ingredients into a light, aerated and palatable food
The move to improve the digestibility of the wild grass seed forerunners of early wheat types through fermentation and baking represents a major step in the development of human food production The unique properties of the proteins in wheat with their ability to form a cohesive mass of dough once the fl our has been hydrated and subjected to the energy of mixing, even by hand, provides the basis
of the transition from fl our to bread The discovery that dough left for long periods of time would increase in volume without being subjected to the high temperatures of baking identifi ed the basis of fermentation The combined effect
of these rheological changes is for the baked mass to increase in volume and give
a product with an even softer, more digestible character and different fl avour After baking, loss of product freshness has as much to do with the characteristics
we expect of the product as it has to do with its age since original manufacture and the conditions under which it is stored Whatever the criteria we use to judge bread staleness it becomes clear that the single most common requirement of fermented products is that they should ideally retain all of the attributes that they had when they left the oven; above all else we expect our bread to be ‘fresh’ When we collect our bread from the baker and it is still warm to the touch we have
no doubt as to its freshness which is reinforced by its aroma, but when we purchase
it cold and wrapped from the store shelf we need convincing as to its freshness The nature of the raw materials and processes used to make bread changes with the passage of time To be able to make our particular bread type we must have an understanding of the complex interactions between our raw materials and the methods we will use in the conversion processes from ingredients to baked product
Trang 40There are a few basic steps that form the basis of all breadmaking They can be listed as follows:
• The continued ‘development’ of the gluten structure initially created in order
to modify the rheological properties of the dough and to improve its ability to expand when gas pressures increase during fermentation
• Cooling and storage of the fi nal product before consumption
2.2 Bread dough development
Dough development is a relatively undefi ned term that covers a number of complex changes that begin when the ingredients fi rst become mixed These changes are associated with the formation of gluten, which requires both the hydration of the proteins in the fl our and the application of energy through the process of kneading The role of energy in the formation of gluten is not always fully appreciated but it is a signifi cant contributor to the breadmaking process There is more to dough development than a simple kneading process The process
of developing bread dough brings about changes in the physical properties of the dough and in particular improvement in its ability to retain the carbon dioxide gas which will later be generated by yeast fermentation This improvement in gas retention ability is particularly important when the dough pieces reach the oven
In the early stages of baking before the dough has set, yeast activity is at its greatest and large quantities of carbon dioxide gas are being generated and released from solution in the aqueous phase of the dough If the dough pieces are
to continue to expand at this time then the dough must be able to retain a large quantity of that gas being generated and it can do this only if we have created a gluten structure with the appropriate physical properties
It is important to distinguish between gas production and gas retention in fermented dough Gas production refers to the generation of carbon dioxide gas as