Yoghurt : science and technology

EEn......Page 0
Yoghurt: Science and Technology......Page 1
Back Cover......Page 2
Copyright Info......Page 6
TOC......Page 7
Preface to second edition......Page 16
Preface to first edition......Page 17
1.2 Evolution of the process......Page 18
1.3 Diversity of fermented milks......Page 20
1.4 Patterns of consumption......Page 22
1.5 Methods of production and classification......Page 24
1.6 References......Page 26
2.1 Introduction......Page 28
2.2.1 Milk as a raw material......Page 31
2.2.2 Separation of cellular matter and other contaminants......Page 33
2.3 Standardisation of fat content in milk......Page 34
2.2 Preliminary treatment of the milk base......Page 30
2.4 Standardisation of the solids-not-fat content in milk......Page 36
2.4.1 Traditional process......Page 38
2.4.2 Addition of milk powder......Page 39
2.4.3 Addition of buttermilk powder......Page 40
2.4.4 Addition of whey powder and/or whey protein concentrates......Page 41
2.4.5 Addition of casein powder......Page 42
2.4.7 Concentration by membrane filtration......Page 44
2.4.8 Addition of non-milk proteins......Page 48
2.5.1 General background......Page 52
2.5.2.2 Optimum concentration......Page 54
2.5.2.4 Legal aspects......Page 56
2.5.2.7 Processing conditions......Page 57
2.6.1 General introduction......Page 58
2.6.2.2 Invert sugar......Page 61
2.6.2.6 Miscellaneous sweeteners......Page 62
2.7.1 Penicillinase......Page 65
2.7.2 Preservatives......Page 67
2.7.3.4 Low sodium......Page 70
2.8.1 Effects on milk constituents......Page 71
2.8.2 Aspects of processing......Page 74
2.9 Heat treatment......Page 78
2.9.2 Production of stimulatory/inhibitory factors......Page 81
2.9.3.1 Effect on the proteins......Page 83
2.9.3.3 Effect on protein/fat interactions......Page 86
2.9.3.4 Effects on other milk constituents......Page 87
2.9.4 Processing effects on the physical properties of the gel......Page 88
2.10.2 Starter organisms......Page 93
2.10.3 Gel formation......Page 96
2.11.2 Two-phase cooling......Page 99
2.12 Addition of fruit/flavouring/colouring ingredients......Page 100
2.12.1 Fruits......Page 102
2.12.2 Flavouring agents......Page 104
2.13.1 Introduction......Page 107
2.13.2.1 Provide protection......Page 108
2.13.2.4 Miscellaneous functions......Page 109
2.13.3.1 Rigid unit containers......Page 110
2.13.3.2 Semi-rigid unit containers......Page 111
2.13.3.3 Flexible unit containers......Page 113
2.13.4 Comparative studies on the permeability of different yoghurt packages......Page 115
2.13.5 Migration of monomers and other compounds......Page 116
2.13.6 Tamper-evident packaging......Page 117
2.13.7 Aluminium foil lids......Page 118
2.13.8 Sterilisation of packaging materials......Page 119
2.13.9 Outer or shipping container......Page 120
2.14 Refrigerated cold storage, transport and distribution......Page 122
2.14.1 The cold store......Page 123
2.14.3 The retail shop and the consumer......Page 124
2.16 References......Page 125
3.1 Home or small-scale production......Page 146
3.1.1 Miscellaneous systems......Page 147
3.1.2 Packaging system......Page 148
3.2.2 Multipurpose vat......Page 151
3.2.3 Mini dairy......Page 152
3.2.4 Small-scale packaging machines......Page 153
3.3 Large-scale production......Page 158
3.3.2 Standardisation of fat content in milk......Page 160
3.3.3.1 Traditional process......Page 164
3.3.3.2 Addition of milk powder......Page 165
3.3.3.4 Membrane concentration of milk......Page 177
3.3.4 Homogenisation......Page 179
3.3.5 Heat treatment......Page 182
3.3.5.1 Batch or multipurpose tanks......Page 183
3.3.5.2 Continuous process......Page 184
3.3.6 Fermentation/incubation of the milk......Page 190
3.3.6.1 Equipment for the production of set yoghurt......Page 193
3.3.6.2 Equipment for the production of stirred yoghurt......Page 197
3.3.7.1 Chilled air......Page 199
3.3.7.2 In-tank cooling......Page 200
3.3.7.3 Continuous coolers......Page 202
3.3.8.1 Centrifugal pump......Page 203
3.3.8.3 Positive displacement pumps......Page 204
3.3.8.5 Diaphragm pump......Page 208
3.3.8.6 Peristaltic pump......Page 209
3.3.9.2 Fittings......Page 213
3.3.9.3 Screens, strainers or structurisers......Page 214
3.3.9.4 Ytron®-Z machine......Page 215
3.3.10.1 Equipment for fruit handling......Page 216
3.3.10.2 Equipment for fruit/yoghurt blending......Page 218
3.3.11 Filling machines......Page 222
3.3.11.1 Machines for filling yoghurt into preformed plastic containers......Page 224
3.3.11.2 Machines for filling form-fill-seal plastic containers......Page 229
3.3.11.3 Machines for filling yoghurt into cartons/paper containers......Page 233
3.4 Mechanisation of yoghurt production and plant design......Page 237
3.5.1 Background......Page 242
3.5.2 The NIZO process......Page 243
3.5.3 Recent developments......Page 245
3.6.1 Levels of automation......Page 246
3.6.2 Area/department 1......Page 248
3.6.3 Area/department 2......Page 249
3.6.5 Area/department 4......Page 250
3.6.6.1 Extended product range......Page 251
3.6.6.5 Batch scheduling software......Page 252
3.6.7 Area/department 6......Page 253
3.6.9 System architecture......Page 254
3.6.10 System security......Page 255
3.7.2 Location of a dairy plant......Page 257
3.7.4 Design and construction of dairy buildings......Page 259
3.7.4.4 Ceilings......Page 260
3.8 Conclusion......Page 261
3.9 References......Page 262
4.1 Primary objectives......Page 266
4.2 Principles of the cleaning process......Page 269
4.3.2 Type of soiling matter......Page 274
4.3.3 Water hardness and quality......Page 275
4.4 Cleaning methods......Page 277
4.4.2 Cleaning-in-place......Page 278
4.4.2.2 Re-use system......Page 280
4.4.3.4 Enzyme-based treatment......Page 281
4.5.4 Concentration of detergent solution......Page 284
4.5.6 Flow rate or velocity......Page 285
4.5.7 Acid wash......Page 286
4.5.8 Plant design......Page 287
4.5.9 Chemical composition of a detergent......Page 288
4.6 Specific cleaning and sterilisation operations of yoghurt processing equipment and utensils......Page 290
4.7 Fundamentals of the sterilisation process......Page 303
4.8.1 Heat......Page 304
4.8.2 Chemical agents......Page 305
4.8.2.2 Quaternary ammonium compounds (QACs)......Page 306
4.8.2.4 Miscellaneous sterilising agents......Page 307
4.8.5 Spraying, fogging or fumigation......Page 308
4.9 Kinetics and mechanisms of microbial destruction......Page 309
4.10.1 Physical examination......Page 313
4.10.3 Bacteriological examination......Page 314
4.12 Nature of pollution......Page 315
4.13 Methods of effluent treatment......Page 316
4.14 References......Page 319
5.1 Introduction......Page 323
5.2 Standard commercial yoghurt......Page 324
5.3 Yoghurt made from different mammalian milks......Page 326
5.3.1 Goat's milk yoghurt......Page 327
5.3.2 SheepÌs milk yoghurt......Page 329
5.3.3 BuffaloÌs milk yoghurt......Page 330
5.4 Pasteurised/UHT/long life/heat shock yoghurt......Page 333
5.4.1 Technology of manufacture......Page 334
5.4.2 Processing effects on properties of product......Page 335
5.5.1 Background......Page 336
5.5.2 Processing aspects......Page 337
5.5.4 Carbonated yoghurt......Page 340
5.6 Lactose hydrolysed yoghurt (LHY)......Page 341
5.7.1 Introduction and nomenclature......Page 343
5.7.2.2 Mechanical separator......Page 346
5.7.2.3 Ultrafiltration (UF)......Page 347
5.7.5 Related products......Page 357
5.7.5.2 Shankleesh or shankalish......Page 360
5.7.2.1 Cloth bag or Berge system......Page 344
5.7.3 Miscellaneous properties......Page 350
5.7.4 Microstructure......Page 352
5.8.1 Background, standards and marketing......Page 361
5.8.2 Technology of manufacture......Page 362
5.8.3 Related products......Page 365
5.9.1 Introduction......Page 366
5.9.2 Processing methods......Page 367
5.9.3 Kishk and related products......Page 370
5.10 Bio-yoghurt......Page 375
5.11 Fat-substitutes yoghurt......Page 376
5.12 Vegetable oil yoghurt......Page 381
5.14 Soy-milk yoghurt......Page 383
5.15 Miscellaneous yoghurt products......Page 386
5.16 Future developments and conclusion......Page 387
5.17 References......Page 388
6.1 Introduction......Page 406
6.1.1 Historical background and classification......Page 407
6.1.2 Modification of starter cultures......Page 413
6.1.3 Potential genetic modifications......Page 414
6.2.1 Milk as a medium for microbial growth......Page 415
6.2.2 Associative growth......Page 416
6.3.1 Compounds that are naturally present in milk......Page 420
6.3.2 Effect of incubation temperature and inoculation rate......Page 421
6.3.4 Hydrogen perxoide (H2O2)......Page 422
6.3.5 Antibiotic residues......Page 423
6.3.6 Detergent and disinfectant residues......Page 425
6.3.8 Bacteriophages......Page 428
6.3.10.1 UF milk......Page 435
6.3.10.3 Lysozyme......Page 437
6.3.10.8 Sweetening agents......Page 438
6.4 Conclusion......Page 439
6.5 References......Page 440
7.2 Carbohydrate metabolism......Page 449
7.2.1 Homolactic fermentation......Page 450
7.2.3 Lactase activity......Page 452
7.2.4 Production of lactic acid......Page 454
7.2.5 Production of exopolysaccharide (EPS)......Page 456
7.2.6 Production of flavour compounds......Page 460
7.2.6.1 Embden–Meyerhof–Parnas pathway......Page 464
7.2.6.2 Threonine aldolase......Page 465
7.3 Protein metabolism......Page 467
7.3.2 Proteolytic enzymes......Page 468
7.3.3 Proteolysis by the yoghurt and bio organisms......Page 470
7.3.4 Products of proteolysis......Page 477
7.4.1.2 Homogenisation......Page 480
7.4.2 Changes in the level of free and esterified fatty acids......Page 482
7.4.3 Changes in the level of volatile fatty acids......Page 483
7.5.1.1 Decrease......Page 484
7.5.1.2 Increase......Page 486
7.5.2 Biosynthesis of folic acid......Page 487
7.5.3 Biosynthesis of niacin......Page 488
7.5.4 Biosynthesis of vitamin B6......Page 489
7.6 Miscellaneous changes......Page 490
7.7 References......Page 492
8.1 Introduction......Page 503
8.2 Methods of starter culture preservation......Page 504
8.2.1 Liquid starters......Page 505
8.2.2 Dried starters......Page 506
8.2.2.1 Growth medium......Page 509
8.2.2.4 Reactivation......Page 511
8.2.3.1 Growth medium plus cryogenic compounds......Page 512
8.2.3.5 Miscellaneous factors......Page 513
8.3 Technology of cell biomass production......Page 515
8.3.2 Concentration of the cell biomass......Page 516
8.3.2.1 Mechanical means......Page 517
8.3.2.3 Diffusion culture......Page 518
8.3.2.4 Cell immobilisation in gels......Page 519
8.4.1 Introductory remarks......Page 520
8.4.3 Mechanically protected systems......Page 521
8.4.3.1 The Lewis system......Page 522
8.4.3.3 Sterile and filtered air systems......Page 523
8.4.3.4 The Tetra Pak system......Page 524
8.4.5 Bacteriophage resistant/inhibitory medium (BRM/BIM)......Page 527
8.6 References......Page 528
9.1 Introduction......Page 532
9.2.1 Available carbohydrates......Page 533
9.2.2 Unavailable carbohydrates......Page 535
9.3 Protein......Page 536
9.4 Lipids......Page 537
9.5 Vitamins and minerals......Page 538
9.6 Yoghurt and health......Page 540
9.6.1 Therapeutic properties of yoghurt......Page 541
9.6.2 Therapeutic properties of bio-yoghurt......Page 545
9.7 Conclusion......Page 547
9.8 References......Page 548
10.1 Introduction......Page 552
10.2.1 Brief introduction......Page 553
10.2.2 Implementation of a HACCP system......Page 555
10.3 Monitoring of process plant......Page 558
10.4.1 Liquid milk......Page 560
10.4.2 Milk powder......Page 562
10.4.3.1 Microbiological examination......Page 564
10.4.3.2 Activity tests......Page 566
10.4.3.3 Absence of contamination......Page 567
10.4.4 Starter cultures for bio-yoghurts......Page 568
10.5.1 Analysis of chemical composition......Page 569
10.5.2.1 Set yoghurt......Page 573
10.5.2.2 Stirred and fluid yoghurt......Page 575
10.5.3.1 Standard yoghurt......Page 582
10.5.3.2 Bio-yoghurts......Page 586
10.5.4 Assessment of organoleptic characteristics......Page 589
10.7 References......Page 595
Different ways in which titratable acidity is expressed and their relative values to % lactic acid......Page 605
Temperature conversion*......Page 607
Volume units......Page 610
Weight/mass units......Page 612
Miscellaneous units......Page 613
Work/energy and other related units......Page 614
Force and pressure units......Page 616
Length and area units......Page 617
Pearsons square method......Page 618
Reference......Page 622