EEn......Page 1
Yoghurt: Science and Technology......Page 2
Back Cover......Page 3
Copyright Info......Page 7
TOC......Page 8
Preface to second edition......Page 17
Preface to first edition......Page 18
1.2 Evolution of the process......Page 19
1.3 Diversity of fermented milks......Page 21
1.4 Patterns of consumption......Page 23
1.5 Methods of production and classification......Page 25
1.6 References......Page 27
2.1 Introduction......Page 29
2.2.1 Milk as a raw material......Page 32
2.2.2 Separation of cellular matter and other contaminants......Page 34
2.3 Standardisation of fat content in milk......Page 35
2.2 Preliminary treatment of the milk base......Page 31
2.4 Standardisation of the solids-not-fat content in milk......Page 37
2.4.1 Traditional process......Page 39
2.4.2 Addition of milk powder......Page 40
2.4.3 Addition of buttermilk powder......Page 41
2.4.4 Addition of whey powder and/or whey protein concentrates......Page 42
2.4.5 Addition of casein powder......Page 43
2.4.7 Concentration by membrane filtration......Page 45
2.4.8 Addition of non-milk proteins......Page 49
2.5.1 General background......Page 53
2.5.2.2 Optimum concentration......Page 55
2.5.2.4 Legal aspects......Page 57
2.5.2.7 Processing conditions......Page 58
2.6.1 General introduction......Page 59
2.6.2.2 Invert sugar......Page 62
2.6.2.6 Miscellaneous sweeteners......Page 63
2.7.1 Penicillinase......Page 66
2.7.2 Preservatives......Page 68
2.7.3.4 Low sodium......Page 71
2.8.1 Effects on milk constituents......Page 72
2.8.2 Aspects of processing......Page 75
2.9 Heat treatment......Page 79
2.9.2 Production of stimulatory/inhibitory factors......Page 82
2.9.3.1 Effect on the proteins......Page 84
2.9.3.3 Effect on protein/fat interactions......Page 87
2.9.3.4 Effects on other milk constituents......Page 88
2.9.4 Processing effects on the physical properties of the gel......Page 89
2.10.2 Starter organisms......Page 94
2.10.3 Gel formation......Page 97
2.11.2 Two-phase cooling......Page 100
2.12 Addition of fruit/flavouring/colouring ingredients......Page 101
2.12.1 Fruits......Page 103
2.12.2 Flavouring agents......Page 105
2.13.1 Introduction......Page 108
2.13.2.1 Provide protection......Page 109
2.13.2.4 Miscellaneous functions......Page 110
2.13.3.1 Rigid unit containers......Page 111
2.13.3.2 Semi-rigid unit containers......Page 112
2.13.3.3 Flexible unit containers......Page 114
2.13.4 Comparative studies on the permeability of different yoghurt packages......Page 116
2.13.5 Migration of monomers and other compounds......Page 117
2.13.6 Tamper-evident packaging......Page 118
2.13.7 Aluminium foil lids......Page 119
2.13.8 Sterilisation of packaging materials......Page 120
2.13.9 Outer or shipping container......Page 121
2.14 Refrigerated cold storage, transport and distribution......Page 123
2.14.1 The cold store......Page 124
2.14.3 The retail shop and the consumer......Page 125
2.16 References......Page 126
3.1 Home or small-scale production......Page 147
3.1.1 Miscellaneous systems......Page 148
3.1.2 Packaging system......Page 149
3.2.2 Multipurpose vat......Page 152
3.2.3 Mini dairy......Page 153
3.2.4 Small-scale packaging machines......Page 154
3.3 Large-scale production......Page 159
3.3.2 Standardisation of fat content in milk......Page 161
3.3.3.1 Traditional process......Page 165
3.3.3.2 Addition of milk powder......Page 166
3.3.3.4 Membrane concentration of milk......Page 178
3.3.4 Homogenisation......Page 180
3.3.5 Heat treatment......Page 183
3.3.5.1 Batch or multipurpose tanks......Page 184
3.3.5.2 Continuous process......Page 185
3.3.6 Fermentation/incubation of the milk......Page 191
3.3.6.1 Equipment for the production of set yoghurt......Page 194
3.3.6.2 Equipment for the production of stirred yoghurt......Page 198
3.3.7.1 Chilled air......Page 200
3.3.7.2 In-tank cooling......Page 201
3.3.7.3 Continuous coolers......Page 203
3.3.8.1 Centrifugal pump......Page 204
3.3.8.3 Positive displacement pumps......Page 205
3.3.8.5 Diaphragm pump......Page 209
3.3.8.6 Peristaltic pump......Page 210
3.3.9.2 Fittings......Page 214
3.3.9.3 Screens, strainers or structurisers......Page 215
3.3.9.4 Ytronยฎ-Z machine......Page 216
3.3.10.1 Equipment for fruit handling......Page 217
3.3.10.2 Equipment for fruit/yoghurt blending......Page 219
3.3.11 Filling machines......Page 223
3.3.11.1 Machines for filling yoghurt into preformed plastic containers......Page 225
3.3.11.2 Machines for filling form-fill-seal plastic containers......Page 230
3.3.11.3 Machines for filling yoghurt into cartons/paper containers......Page 234
3.4 Mechanisation of yoghurt production and plant design......Page 238
3.5.1 Background......Page 243
3.5.2 The NIZO process......Page 244
3.5.3 Recent developments......Page 246
3.6.1 Levels of automation......Page 247
3.6.2 Area/department 1......Page 249
3.6.3 Area/department 2......Page 250
3.6.5 Area/department 4......Page 251
3.6.6.1 Extended product range......Page 252
3.6.6.5 Batch scheduling software......Page 253
3.6.7 Area/department 6......Page 254
3.6.9 System architecture......Page 255
3.6.10 System security......Page 256
3.7.2 Location of a dairy plant......Page 258
3.7.4 Design and construction of dairy buildings......Page 260
3.7.4.4 Ceilings......Page 261
3.8 Conclusion......Page 262
3.9 References......Page 263
4.1 Primary objectives......Page 267
4.2 Principles of the cleaning process......Page 270
4.3.2 Type of soiling matter......Page 275
4.3.3 Water hardness and quality......Page 276
4.4 Cleaning methods......Page 278
4.4.2 Cleaning-in-place......Page 279
4.4.2.2 Re-use system......Page 281
4.4.3.4 Enzyme-based treatment......Page 282
4.5.4 Concentration of detergent solution......Page 285
4.5.6 Flow rate or velocity......Page 286
4.5.7 Acid wash......Page 287
4.5.8 Plant design......Page 288
4.5.9 Chemical composition of a detergent......Page 289
4.6 Specific cleaning and sterilisation operations of yoghurt processing equipment and utensils......Page 291
4.7 Fundamentals of the sterilisation process......Page 304
4.8.1 Heat......Page 305
4.8.2 Chemical agents......Page 306
4.8.2.2 Quaternary ammonium compounds (QACs)......Page 307
4.8.2.4 Miscellaneous sterilising agents......Page 308
4.8.5 Spraying, fogging or fumigation......Page 309
4.9 Kinetics and mechanisms of microbial destruction......Page 310
4.10.1 Physical examination......Page 314
4.10.3 Bacteriological examination......Page 315
4.12 Nature of pollution......Page 316
4.13 Methods of effluent treatment......Page 317
4.14 References......Page 320
5.1 Introduction......Page 324
5.2 Standard commercial yoghurt......Page 325
5.3 Yoghurt made from different mammalian milks......Page 327
5.3.1 Goat's milk yoghurt......Page 328
5.3.2 Sheepรs milk yoghurt......Page 330
5.3.3 Buffaloรs milk yoghurt......Page 331
5.4 Pasteurised/UHT/long life/heat shock yoghurt......Page 334
5.4.1 Technology of manufacture......Page 335
5.4.2 Processing effects on properties of product......Page 336
5.5.1 Background......Page 337
5.5.2 Processing aspects......Page 338
5.5.4 Carbonated yoghurt......Page 341
5.6 Lactose hydrolysed yoghurt (LHY)......Page 342
5.7.1 Introduction and nomenclature......Page 344
5.7.2.2 Mechanical separator......Page 347
5.7.2.3 Ultrafiltration (UF)......Page 348
5.7.5 Related products......Page 358
5.7.5.2 Shankleesh or shankalish......Page 361
5.7.2.1 Cloth bag or Berge system......Page 345
5.7.3 Miscellaneous properties......Page 351
5.7.4 Microstructure......Page 353
5.8.1 Background, standards and marketing......Page 362
5.8.2 Technology of manufacture......Page 363
5.8.3 Related products......Page 366
5.9.1 Introduction......Page 367
5.9.2 Processing methods......Page 368
5.9.3 Kishk and related products......Page 371
5.10 Bio-yoghurt......Page 376
5.11 Fat-substitutes yoghurt......Page 377
5.12 Vegetable oil yoghurt......Page 382
5.14 Soy-milk yoghurt......Page 384
5.15 Miscellaneous yoghurt products......Page 387
5.16 Future developments and conclusion......Page 388
5.17 References......Page 389
6.1 Introduction......Page 407
6.1.1 Historical background and classification......Page 408
6.1.2 Modification of starter cultures......Page 414
6.1.3 Potential genetic modifications......Page 415
6.2.1 Milk as a medium for microbial growth......Page 416
6.2.2 Associative growth......Page 417
6.3.1 Compounds that are naturally present in milk......Page 421
6.3.2 Effect of incubation temperature and inoculation rate......Page 422
6.3.4 Hydrogen perxoide (H2O2)......Page 423
6.3.5 Antibiotic residues......Page 424
6.3.6 Detergent and disinfectant residues......Page 426
6.3.8 Bacteriophages......Page 429
6.3.10.1 UF milk......Page 436
6.3.10.3 Lysozyme......Page 438
6.3.10.8 Sweetening agents......Page 439
6.4 Conclusion......Page 440
6.5 References......Page 441
7.2 Carbohydrate metabolism......Page 450
7.2.1 Homolactic fermentation......Page 451
7.2.3 Lactase activity......Page 453
7.2.4 Production of lactic acid......Page 455
7.2.5 Production of exopolysaccharide (EPS)......Page 457
7.2.6 Production of flavour compounds......Page 461
7.2.6.1 EmbdenโMeyerhofโParnas pathway......Page 465
7.2.6.2 Threonine aldolase......Page 466
7.3 Protein metabolism......Page 468
7.3.2 Proteolytic enzymes......Page 469
7.3.3 Proteolysis by the yoghurt and bio organisms......Page 471
7.3.4 Products of proteolysis......Page 478
7.4.1.2 Homogenisation......Page 481
7.4.2 Changes in the level of free and esterified fatty acids......Page 483
7.4.3 Changes in the level of volatile fatty acids......Page 484
7.5.1.1 Decrease......Page 485
7.5.1.2 Increase......Page 487
7.5.2 Biosynthesis of folic acid......Page 488
7.5.3 Biosynthesis of niacin......Page 489
7.5.4 Biosynthesis of vitamin B6......Page 490
7.6 Miscellaneous changes......Page 491
7.7 References......Page 493
8.1 Introduction......Page 504
8.2 Methods of starter culture preservation......Page 505
8.2.1 Liquid starters......Page 506
8.2.2 Dried starters......Page 507
8.2.2.1 Growth medium......Page 510
8.2.2.4 Reactivation......Page 512
8.2.3.1 Growth medium plus cryogenic compounds......Page 513
8.2.3.5 Miscellaneous factors......Page 514
8.3 Technology of cell biomass production......Page 516
8.3.2 Concentration of the cell biomass......Page 517
8.3.2.1 Mechanical means......Page 518
8.3.2.3 Diffusion culture......Page 519
8.3.2.4 Cell immobilisation in gels......Page 520
8.4.1 Introductory remarks......Page 521
8.4.3 Mechanically protected systems......Page 522
8.4.3.1 The Lewis system......Page 523
8.4.3.3 Sterile and filtered air systems......Page 524
8.4.3.4 The Tetra Pak system......Page 525
8.4.5 Bacteriophage resistant/inhibitory medium (BRM/BIM)......Page 528
8.6 References......Page 529
9.1 Introduction......Page 533
9.2.1 Available carbohydrates......Page 534
9.2.2 Unavailable carbohydrates......Page 536
9.3 Protein......Page 537
9.4 Lipids......Page 538
9.5 Vitamins and minerals......Page 539
9.6 Yoghurt and health......Page 541
9.6.1 Therapeutic properties of yoghurt......Page 542
9.6.2 Therapeutic properties of bio-yoghurt......Page 546
9.7 Conclusion......Page 548
9.8 References......Page 549
10.1 Introduction......Page 553
10.2.1 Brief introduction......Page 554
10.2.2 Implementation of a HACCP system......Page 556
10.3 Monitoring of process plant......Page 559
10.4.1 Liquid milk......Page 561
10.4.2 Milk powder......Page 563
10.4.3.1 Microbiological examination......Page 565
10.4.3.2 Activity tests......Page 567
10.4.3.3 Absence of contamination......Page 568
10.4.4 Starter cultures for bio-yoghurts......Page 569
10.5.1 Analysis of chemical composition......Page 570
10.5.2.1 Set yoghurt......Page 574
10.5.2.2 Stirred and fluid yoghurt......Page 576
10.5.3.1 Standard yoghurt......Page 583
10.5.3.2 Bio-yoghurts......Page 587
10.5.4 Assessment of organoleptic characteristics......Page 590
10.7 References......Page 596
Different ways in which titratable acidity is expressed and their relative values to % lactic acid......Page 606
Temperature conversion*......Page 608
Volume units......Page 611
Weight/mass units......Page 613
Miscellaneous units......Page 614
Work/energy and other related units......Page 615
Force and pressure units......Page 617
Length and area units......Page 618
Pearsons square method......Page 619
Reference......Page 623