Meat refrigeration

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 vi Contents 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 viii Contents 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 x Contents 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