Contents
Part 1 Refrigeration and meat quality
1 Microbiology of refrigerated meat 3
1.1 Factors affecting the refrigerated shelf-life of meat 4
1.1.1 Initial microbial levels 4
1.1.2 Temperature 6
1.1.3 Relative humidity 11
1.2 Other considerations 12
1.2.1 Bone taint 13
1.2.2 Cold deboning 14
1.2.3 Hot deboning 15
1.3 Conclusions 16
1.4 References 16
2 Drip production in meat refrigeration 21
2.1 Biochemistry of meat 22
2.1.1 Structure of muscle 22
2.1.2 Changes after slaughter 25
2.1.3 Water relationships in meat 27
2.1.4 Ice formation in muscle tissues 29
2.2 Measurement of drip 30
2.3 Factors affecting the amount of drip 30
2.3.1 Animal factors 30
2.3.2 Refrigeration factors 33
2.3.3 Chilled storage 36
2.4 Conclusions 40
2.5 References 41
3 Effect of refrigeration on texture of meat 43
3.1 Muscle shortening 44
3.1.1 Mechanism of shortening 45
3.1.2 Preventing shortening 49
3.2 Development of conditioning (ageing) 50
3.2.1 Mechanism of ageing 51
3.2.2 Prediction of tenderness 52
3.2.3 Consumer appreciation of ageing 52
3.2.4 Preslaughter factors 53
3.2.5 Pre-rigor factors 54
3.2.6 At chill temperatures 56
3.2.7 At frozen temperatures 57
3.2.8 At higher temperatures 58
3.3 Influence of chilling on texture 59
3.3.1 Lamb 59
3.3.2 Pork 59
3.3.3 Beef 61
3.4 Influence of freezing on texture 61
3.4.1 Lamb 62
3.4.2 Pork 63
3.4.3 Beef 63
3.5 Influence of thawing on texture 64
3.6 Conclusions 64
3.7 References 66
4 Colour changes in chilling, freezing and storage of meat 71
4.1 Meat colour 71
4.2 Factors affecting the colour of meat 73
4.2.1 Live animal 73
4.2.2 Chilling 73
4.2.3 Conditioning 74
4.2.4 Chilled storage 75
4.2.5 Freezing 76
4.2.6 Frozen storage 76
4.2.7 Thawing 78
4.2.8 Retail display 79
4.3 Conclusions 81
4.4 References 82
5 Influence of refrigeration on evaporative weight loss from
meat 85
5.1 Theoretical considerations 86
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5.2 Weight loss in practice 87
5.2.1 Chilling 88
5.2.2 Chilled storage 90
5.2.3 Freezing and frozen storage 91
5.2.4 Retail display 92
5.3 Overall 93
5.4 Conclusions 94
5.5 References 95
Part 2 The cold chain from carcass to consumer
6 Primary chilling of red meat 99
6.1 Introduction 99
6.2 Conventional chilling 100
6.2.1 Beef 100
6.2.2 Lamb, mutton and goat chilling 110
6.2.3 Pork 115
6.2.4 Chilling of offal 118
6.3 Novel systems with future potential 119
6.3.1 Accelerated chilling systems 119
6.3.2 Spray chilling 123
6.3.3 Immersion chilling 125
6.3.4 Ice bank chilling 127
6.3.5 Combined systems 128
6.3.6 Protective coatings 129
6.3.7 Hot boning 129
6.4 Conclusions 132
6.5 References 132
7 Freezing of meat 137
7.1 Freezing rate 137
7.2 Freezing systems 140
7.2.1 Air 140
7.3 Contact freezers 142
7.4 Cryogenic freezing 144
7.5 Freezing of specific products 145
7.5.1 Meat blocks 145
7.5.2 Beef quarters 145
7.5.3 Mutton carcasses 146
7.5.4 Offal 146
7.5.5 Small products 147
7.6 Tempering and crust freezing 149
7.6.1 Pork loin chopping 149
7.6.2 High speed ham slicing 150
Contents vii
7.6.3 High speed bacon slicing 150
7.7 Conclusions 155
7.8 References 155
8 Thawing and tempering 159
8.1 Considerations 160
8.2 Quality and microbiological considerations 161
8.3 Thawing systems 163
8.3.1 Conduction 166
8.3.2 Electrical methods 166
8.3.3 Published thawing data for different meat cuts 168
8.3.4 Commercial practice 176
8.4 Tempering 178
8.4.1 Requirements for cutting and processing
equipment 178
8.4.2 Requirements for prebreaking 179
8.4.3 Microwave tempering 182
8.4.4 Commercial practice 185
8.5 Conclusions 186
8.6 References 187
9 Transportation 191
9.1 Sea transport 191
9.2 Air transport 193
9.3 Overland transport 193
9.3.1 Types of refrigeration system 194
9.3.2 Observations of transport 195
9.3.3 Problems particular to local delivery vehicles 197
9.3.4 Design and operation of local distribution
vehicles 198
9.4 Changes during transportation 202
9.5 Conclusions 204
9.6 References 204
10 Chilled and frozen storage 207
10.1 Storage life terms 207
10.2 Chilled storage 208
10.2.1 Unwrapped meat 209
10.2.2 Wrapped meat 211
10.2.3 Cooked products 214
10.3 Frozen storage 216
10.3.1 Oxidative rancidity 216
10.3.2 Prefreezing treatment 218
10.3.3 Freezing process 220
10.3.4 During frozen storage 221
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10.4 Types of storage room 224
10.4.1 Bulk storage rooms 224
10.4.2 Controlled atmosphere storage rooms 225
10.4.3 Jacketed cold stores 225
10.5 Conclusions 225
10.6 References 226
11 Chilled and frozen retail display 231
11.1 Chilled display of wrapped meat and meat products 231
11.1.1 Factors affecting display life 232
11.1.2 Layout of chilled cabinet 233
11.1.3 Air curtain 234
11.1.4 Cabinet development 235
11.1.5 Computer modelling 236
11.1.6 Store conditions 236
11.2 Retail display of unwrapped meat and delicatessen
products 237
11.2.1 Types of cabinet 238
11.2.2 Appearance changes 238
11.2.3 Effects of environmental conditions 239
11.3 Retail display of frozen wrapped meat 241
11.3.1 Factors controlling display life 241
11.4 Overall cabinet design 244
11.4.1 Air circulation and temperatures 245
11.4.2 Effect of doors and lids 246
11.4.3 Effect of radiant heat 247
11.4.4 Measurement methods 247
11.5 Conclusions 248
11.6 References 249
12 Consumer handling 251
12.1 Consumer attitudes to food poisoning 252
12.2 Shopping habits and transport from retail store to
the home 252
12.3 Refrigerated storage in the home 255
12.4 Temperatures in domestic food storage 256
12.5 Performance testing of domestic refrigerators 262
12.5.1 Performance of empty appliances 263
12.5.2 Performance of loaded appliances 263
12.5.3 Effect of loading with warm (20°C) food
products 264
12.5.4 Effect of door openings 264
12.6 Performance testing of domestic freezers 265
12.7 Conclusions 267
12.8 References 269
Contents ix
Part 3 Process control
13 Thermophysical properties of meat 273
13.1 Chilling 274
13.1.1 Thermal conductivity 274
13.1.2 Specific heat 274
13.1.3 Enthalpies 276
13.2 Freezing, thawing and tempering 277
13.2.1 Ice content 277
13.2.2 Heat extraction 277
13.2.3 Thermal conductivity 278
13.2.4 Density 280
13.3 Mathematical models 280
13.4 Conclusions 280
13.5 References 281
14 Temperature measurement 283
14.1 Instrumentation 284
14.1.1 Hand-held digital thermometers 284
14.1.2 Temperature recorders 285
14.1.3 Time–temperature indicators 288
14.2 Calibration 289
14.3 Measuring temperature data 289
14.3.1 Contact non-destructive methods 290
14.3.2 Non-contact non-destructive methods 290
14.3.3 Contact destructive methods 292
14.3.4 Storage 294
14.3.5 Distribution 295
14.3.6 Retail 296
14.4 Interpreting temperature data 298
14.4.1 Example 1 298
14.4.2 Example 2 299
14.5 Conclusions 301
14.6 References 302
15 Specifying, designing and optimising refrigeration systems 303
15.1 Process specification 303
15.1.1 Throughput 304
15.1.2 Temperature requirements 304
15.1.3 Weight loss 304
15.1.4 Future use 305
15.1.5 Plant layout 305
15.2 Engineering specification 306
15.2.1 Environmental conditions 307
15.2.2 Room size 308
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15.2.3 Refrigeration loads 308
15.2.4 Refrigeration plant capacity 311
15.2.5 Relative humidity 312
15.2.6 Ambient design conditions 313
15.2.7 Defrosts 313
15.2.8 Engineering design summary 313
15.3 Procurement 314
15.3.1 Plant design 314
15.4 Optimisation 317
15.4.1 Process definition 317
15.5 Conclusions 320
16 Secondary chilling of meat and meat products 321
16.1 Cooked meat 322
16.1.1 Legislation 322
16.1.2 Practical 323
16.1.3 Experimental studies 324
16.2 Pastry products 328
16.2.1 Commerical operations 328
16.2.2 Experimental studies 329
16.3 Solid/liquid mixtures 330
16.4 Process cooling 332
16.5 Cook–chill 332
16.5.1 Cook–chill guidelines 333
16.5.2 Practical cooling time data 334
16.5.3 Refrigeration problems in practice 336
16.6 Conclusions 338
16.7 References 338
Index 341
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