Malts and Malting

787 Pages·2016·12.8 MB·English

by  Briggs D.E.

Malts and Malting
Dennis E. Briggs
Department of Biochemistry
University of Birmingham
Birmingham
UK
BLACKIE ACADEMIC & PROFESSIONAL
An Imprint of Chapman & Hall
London • Weinheim • New York • Tokyo • Melbourne - Madras
Published by Blackie Academic & Professional, an imprint of
Thomson Science, 2-6 Boundary Row, London SE18HN, UK
Thomson Science, 2-6 Boundary Row, London SE1 8HN, UK
Thomson Science, 115 Fifth Avenue, New York, NY 10003, USA
Thomson Science, Suite 750,400 Market Street, Philadelphia, PA
19106, USA
Thomson Science, Pappelallee 3, 69469 Weinheim, Germany
First edition 1998
© 1998 Dennis E. Briggs
Thomson Science is a division of International Thomson Publishing l(T)P
Typeset in 10/12pt Times by Type Study, Scarborough
Printed in Great Britain by T. J. International Ltd, Padstow, Cornwall
ISBN 0 412 29800 7
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regard to the accuracy of the information contained in this book and
cannot accept any legal responsibility or liability for any errors or
omissions that may be made.
A catalogue record for this book is available from the British Library
Library of Congress Catalog Card Number 97-73406
Printed on permanent acid-free text paper, manufactured in
@
accordance with ANSI/NISO Z39.48-1992 and ANSI/NISO
Z39.48-1984 (Permanence of Paper).
Contents
Preface xv
Abbreviations xvii
1 An introduction to malts and their uses 1
1.1 Introduction 4
1.2 Malting in outline 8
1.3 Coffee substitutes 9
1.4 Malt flours and malted wheat used in baking 10
1.5 Ancient Middle Eastern methods of brewing 11
1.6 Bouza, merissa and busaa 13
1.7 Other opaque beers, fermented gruels and porridges 16
1.8 Clear beers and stouts 23
1.9 Malt extracts 23
1.10 Diastase 27
1.11 Breakfast cereals and pre-digested foods 27
1.12 Distilled products 28
1.13 Malt vinegar 31
1.14 Other uses of malt 33
2 Grains and pulses 35
2.1 The cereal grains, peas and beans 35
2.2 The barley plant 35
2.3 The quiescent barley grain 41
2.4 Barley classification and varietal identification 50
2.5 Other cereal grains 54
2.5.1 Wheats 54
2.5.2 Rye 55
2.5.3 Triticale 55
2.5.4 Oats 56
2.5.5 Rice 56
2.5.6 Maize 56
2.5.7 Sorghum 57
2.5.8 The millets 57
2.6 Pulses or legumes 58
VI MALTS AND MALTING
2.7 Physical changes occurring in malting barley 59
2.8 Germination and modification in other species 66
2.9 Barley cultivation 66
2.10 The improvement of the barley crop 73
3 Grain physiology 79
3.1 Some general considerations 79
3.2 The functions of different tissues of barley and other grains 80
3.3 The statistics of grain testing 86
3.4 Water uptake by grains 88
3.5 The permeability of grains to solutes 96
3.6 Assessments of husk content and some aspects of grain
quality 98
3.7 Viability, germinability and dormancy 99
3.7.1 Germination 100
3.7.2 Viability 100
3.7.3 Dormancy 101
3.7.4 Tests for germinative capacity 102
3.7.5 Tests for germinative energy 104
3.7.6 Factors influencing germination 108
3.7.7 Overcoming dormancy 113
3.8 The respiratory metabolism of grain 117
3.9 Microbes and malting 128
4 The biochemistry of malting 133
4.1 Introduction 133
4.2 The composition of grains 134
4.2.1 Quiescent grain 134
4.2.2 Changes occurring during malting 134
4.2.3 The husk and pericarp 136
4.2.4 The testa 138
4.2.5 The embryo 139
4.2.6 The aleurone layer and nucellar tissue 140
4.2.7 The starchy endosperm 141
4.3 The chemical changes occurring during malting 143
4.4 The carbohydrates of quiescent and malting grains 148
4.5 Starch and its breakdown 150
4.5.1 The enzymes that degrade starch 154
4.6 Non-starch polysaccharides 159
4.6.1 Breakdown of non-starch polysaccharides 165
4.7 Regularities in the carbohydrate composition of barley 168
4.8 Proteins and amino acids in barley 169
4.9 Nucleic acids and related substances 184
4.10 Other nitrogenous grain components 186
CONTENTS Vll
4.11 Lipids 187
4.12 Phosphates and inorganic constituents 190
4.13 Vitamins and yeast growth factors 193
4.14 Miscellaneous substances 194
4.15 Phenols and related substances 197
4.16 The regulation of modification in malting 205
4.16.1 The influence of the barley sample and moisture
content 206
4.16.2 Temperature, germination and malting 207
4.16.3 Grain metabolism, enzyme development and
modification 209
4.17 Some chemical and biochemical aspects of roasting and
kilning 218
5 The principles of mashing 229
5.1 Introduction 229
5.2 Commercial mashing processes 230
5.2.1 Liquor 230
5.2.2 Grist 230
5.2.3 Infusion mashing 231
5.2.4 Temperature-programmed mashing 232
5.2.5 Decoction mashing 233
5.2.6 Double-mashing 235
5.2.7 Other mashing methods 235
5.3 Some aspects of mashing biochemistry 237
5.4 Wort separation and sparging 242
6 The selection and purchase of grain 245
6.1 Introduction 245
6.2 Sampling 248
6.3 Hand evaluation and some laboratory tests 251
6.4 Moisture content 256
6.5 Water uptake by grains and distribution in the starchy
endosperm 258
6.6 Grain size 259
6.7 The bulk density of grain 260
6.8 The specific gravity of grains 260
6.9 The nitrogen or protein content of barley 261
6.10 Determinations of germinative capacity 263
6.11 Tests of germinative energy 265
6.12 Grain composition 267
6.13 Microbes, mycotoxins and chemical residues 269
Vlll MALTS AND MALTING
7 Grain in store 271
7.1 Introduction 271
7.2 The microbes associated with grains 273
7.3 Insects and mite pests stored in grain 275
7.3.1 The control of insects and mites 280
7.4 Other pests of stored grain 283
7.5 Grain heating 284
7.6 Moisture distribution in stored grain 286
7.6.1 Adjusting grain moisture content 287
7.7 Germinability, viability and grain characteristics 289
7.8 Hazards in grain stores 291
7.9 Grain aeration and ventilation 291
7.10 Operating grain stores: good housekeeping 292
8 Handling and storing grains and malts 294
8.1 Introduction 294
8.2 Grain intake 295
8.3 Moving grain 298
8.3.1 Introduction 298
8.3.2 Screw or worm conveyors 299
8.3.3 Chain-and-flight, cord-and-flight and en masse
conveyors 300
8.3.4 Flexible-belt conveyors 303
8.3.5 Jog conveyors 304
8.3.6 Grain elevators 304
8.3.7 Grain throwers 306
8.3.8 Sampling devices 306
8.3.9 Pneumatic grain conveying systems 307
8.4 Mixing and blending 308
8.5 Weighing 309
8.6 Grain pre-cleaning, cleaning and grading 310
8.6.1 General considerations 310
8.6.2 Magnetic separators 311
8.6.3 De-awners and polishers 311
8.6.4 Aspirators 314
8.6.5 Pre-cleaning machinery 314
8.7 Cleaning and grading 316
8.7.1 Screening 316
8.7.2 Cylinder and disc separators 319
8.7.3 Pneumatic cleaners 322
8.7.4 Destoning 322
8.7.5 Spiral separators 324
8.7.6 Dust and light impurities 324
8.8 Grain drying 327
CONTENTS IX
8.9 Applications of insecticides and fumigants 332
8.10 Grain storage facilities 333
8.11 Handling malts 338
8.11.1 Green malt 338
8.11.2 Dry malt 338
8.11.3 Malt storage 339
8.12 Changes in grain weight and volume during processing 339
8.13 Malt delivery 339
8.14 Organization 340
9 Malting technology 341
9.1 Introduction 341
9.2 Floor-malting 343
9.3 Abraders 352
9.4 Grain washing and destoning 354
9.5 Weights, volumes and capacities 357
9.6 Water for steeping 359
9.7 Makings' effluent 360
9.8 Steeping 369
9.8.1 Early steeping systems 369
9.8.2 Novel steep designs 372
9.8.3 Hopper bottomed steeps 373
9.8.4 Modern flat-bed steeps 384
9.8.5 Air conditioning for steeps 387
9.8.6 Spray-steeping 387
9.8.7 Applications of additives 389
9.8.8 Squeeze malting 389
9.8.9 The regulation of steeping 390
9.9 Malting systems 391
9.9.1 Pneumatic malting systems: an introduction 391
9.9.2 Pneumatic malting systems: general considerations 397
9.9.3 Drum malting plant 404
9.9.4 Compartment maltings 408
9.9.5 Kropff malting boxes 415
9.9.6 Popp malting boxes 416
9.10 Multi-function systems 417
9.10.1 Germination and kilning boxes 417
9.10.2 Multi-function vessels: SGVs and SGKVs 418
9.10.3 Semicontinuous malting plants 426
9.10.4 Continuous malting plants 434
9.11 Kilning 439
9.11.1 Introduction 439
9.11.2 More recent, shallow-loaded kilns 441
9.11.3 Deep-loading kilns 452
X MALTS AND MALTING
9.11.4 Less common types of kiln 457
9.11.5 Linked kilns and modern double-decked kilns 461
9.11.6 Kiln automation 463
9.12 Cooling and deculming 464
9.13 Malt storage 466
9.14 By-products: culms and malt dust 468
9.15 Roasting plant 469
9.16 Malt blending and dispatch 471
9.17 The organization of maltings 472
10 Energy used in malting 475
10.1 Introduction 475
10.2 Sources of heat for barley drying and malt kilning 477
10.3 The physics of water removal from grain 481
10.4 Barley drying 488
10.5 Conditions during germination 490
10.6 Kilning malt 490
10.7 The removal of moisture from green malt or barley 497
10.7.1 Mollier drying diagram 498
10.8 Drying on kiln 501
10.8.1 Minimizing kilning costs 502
10.8.2 The comparative themal efficiencies of kilns 512
11 Experimental malting 513
11.1 Introduction 513
11.2 General considerations 514
11.3 Types of small-scale malting equipment 518
11.4 The assessment of'micromalts' 530
12 Competitors for malt 533
12.1 Introduction 533
12.2 The common cereal grains 536
12.3 Analyses of adjuncts 538
12.4 Whole cereal grains 541
12.4.1 Raw cereal grains 541
12.4.2 Cooked, intact cereal grains 546
12.5 Grain preparations 548
12.5.1 Grits 548
12.5.2 Flaked cereals 549
12.5.3 Extruded cereals 551
12.5.4 Flours 552
12.6 Refined starches 555
12.7 Sugars 557
12.7.1 Sucrose and invert sugars 557
CONTENTS XI
12.7.2 Sugars and syrups from purified starch 560
12.8 Malt extracts and wort replacement syrups 564
12.9 Caramels 569
12.10 Industrial enzymes 570
12.11 The future 577
13 Malt analysis 579
13.1 Introduction 579
13.2 Sampling malts 581
13.3 Statistics of analyses 581
13.4 The sensory evaluation of malts 582
13.5 Corn size 586
13.6 Grain density 587
13.7 Permeability, porosity and compressibility 589
13.8 Malt germinability 589
13.9 Patterns of modification 589
13.10 Mechanical assessments of malt modification 591
13.11 Half-grain mashing 595
13.12 Moisture content 595
13.13 Cold water extract 596
13.14 Hot water extract 596
13.15 Some determinations made on laboratory worts 604
13.15.1 Colour 605
13.15.2 Wort fermentability and attenuation limits 605
13.16 Mash viscosity 606
13.17 Nitrogen fractions of malt 607
13.18 Enzymes in malt 610
13.19 Gums and hemicelluloses 611
13.20 Phenolic materials 612
13.21 Some other analyses 613
13.22 Microbes and microbial metabolites 614
14 Malting conditions and their influences in malting 615
14.1 Introduction 615
14.2 Floor-malting 616
14.3 Pneumatic malting 620
14.4 Malting losses 622
14.5 Changes that occur during malting 624
14.6 Barley characteristics and malting 631
14.7 Correlation between barley analyses and malt quality 636
14.8 Steeping 642
14.8.1 Steep liquor 642
14.8.2 Steeping: some general considerations 645
14.8.3 Commercial steeping schedules 649