Meat refrigeration S J James and C James Cambridge England Published by Woodhead Publishing Limited, Abington Hall, Abington Cambridge CB1 6AH, England www.woodhead-publishing.com Published in North America by CRC Press LLC, 2000 Corporate Blvd, NW Boca Raton FL 33431, USA First published 2002, Woodhead Publishing Ltd and CRC Press LLC © The University of Bristol 2002 The authors have asserted their moral rights This book contains information obtained from authentic and highly regarded sources Reprinted material is quoted with permission, and sources are indicated Reasonable efforts have been made to publish reliable data and information, but the authors and the publishers cannot assume responsibility for the validity of all materials Neither the authors nor the publishers, nor anyone else associated with this publication, shall be liable for any loss, damage or liability directly or indirectly caused or alleged to be caused by this book Neither this book nor any part may be reproduced 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design by The ColourStudio Typeset by SNP Best-set Typesetter Ltd., Hong Kong Printed by TJ International, Padstow, Cornwall, England Related titles from Woodhead’s food science, technology and nutrition list: Meat processing (ISBN 85573 583 0) This major new collection summarises key developments in research, from improving raw meat quality and safety issues to developments in meat processing and specific aspects of meat product quality such as colour, flavour and texture HACCP in the meat industry (ISBN 85573 448 6) Following the crises involving BSE and E coli the meat industry has been left with an enormous consumer confidence problem In order to regain the trust of the general public the industry must establish and adhere to strict hygiene and hazard control systems HACCP is a systematic approach to the identification, evaluation and control of food safety hazards It is being applied across the world, with countries such as the USA, Australia, New Zealand and the UK leading the way However, effective implementation in the meat industry remains difficult and controversial This book is a survey of key principles and best practice, providing an authoritative guide to making HACCP systems work successfully in the meat industry Lawrie’s meat science (ISBN 85573 395 1) This book remains a standard for both students and professionals in the meat industry It provides a systematic account of meat science from the conception of the animal until human consumption, presenting the fundamentals of meat science This sixth edition incorporates the significant advances in meat science which have taken place during the past decade including our increasingly precise understanding of the structure of the muscle, as well as the identification of the aberrations in DNA which lead to the development of BSE syndrome in meat Details of these books and a complete list of Woodhead titles can be obtained by: visiting our web site at: www.woodhead-publishing.com contacting Customer Services (e-mail: sales@woodheadpublishing.com; tel: +44 (0)1223 891358 ext 30; fax: +44 (0)1223 893694; address: Woodhead Publishing Ltd, Abington Hall, Abington, Cambridge CB1 6AH, England) Contents Part Refrigeration and meat quality Microbiology of refrigerated meat 1.1 Factors affecting the refrigerated shelf-life of meat 1.1.1 Initial microbial levels 1.1.2 Temperature 1.1.3 Relative humidity 1.2 Other considerations 1.2.1 Bone taint 1.2.2 Cold deboning 1.2.3 Hot deboning 1.3 Conclusions 1.4 References 4 11 12 13 14 15 16 16 Drip production in meat refrigeration 2.1 Biochemistry of meat 2.1.1 Structure of muscle 2.1.2 Changes after slaughter 2.1.3 Water relationships in meat 2.1.4 Ice formation in muscle tissues 2.2 Measurement of drip 2.3 Factors affecting the amount of drip 2.3.1 Animal factors 2.3.2 Refrigeration factors 2.3.3 Chilled storage 21 22 22 25 27 29 30 30 30 33 36 vi Contents 2.4 2.5 Conclusions References 40 41 Effect of refrigeration on texture of meat 3.1 Muscle shortening 3.1.1 Mechanism of shortening 3.1.2 Preventing shortening 3.2 Development of conditioning (ageing) 3.2.1 Mechanism of ageing 3.2.2 Prediction of tenderness 3.2.3 Consumer appreciation of ageing 3.2.4 Preslaughter factors 3.2.5 Pre-rigor factors 3.2.6 At chill temperatures 3.2.7 At frozen temperatures 3.2.8 At higher temperatures 3.3 Influence of chilling on texture 3.3.1 Lamb 3.3.2 Pork 3.3.3 Beef 3.4 Influence of freezing on texture 3.4.1 Lamb 3.4.2 Pork 3.4.3 Beef 3.5 Influence of thawing on texture 3.6 Conclusions 3.7 References 43 44 45 49 50 51 52 52 53 54 56 57 58 59 59 59 61 61 62 63 63 64 64 66 Colour changes in chilling, freezing and storage of meat 4.1 Meat colour 4.2 Factors affecting the colour of meat 4.2.1 Live animal 4.2.2 Chilling 4.2.3 Conditioning 4.2.4 Chilled storage 4.2.5 Freezing 4.2.6 Frozen storage 4.2.7 Thawing 4.2.8 Retail display 4.3 Conclusions 4.4 References 71 71 73 73 73 74 75 76 76 78 79 81 82 Influence of refrigeration on evaporative weight loss from meat 5.1 Theoretical considerations 85 86 Contents 5.2 5.3 5.4 5.5 Weight loss in practice 5.2.1 Chilling 5.2.2 Chilled storage 5.2.3 Freezing and frozen storage 5.2.4 Retail display Overall Conclusions References vii 87 88 90 91 92 93 94 95 Part The cold chain from carcass to consumer Primary chilling of red meat 6.1 Introduction 6.2 Conventional chilling 6.2.1 Beef 6.2.2 Lamb, mutton and goat chilling 6.2.3 Pork 6.2.4 Chilling of offal 6.3 Novel systems with future potential 6.3.1 Accelerated chilling systems 6.3.2 Spray chilling 6.3.3 Immersion chilling 6.3.4 Ice bank chilling 6.3.5 Combined systems 6.3.6 Protective coatings 6.3.7 Hot boning 6.4 Conclusions 6.5 References 99 99 100 100 110 115 118 119 119 123 125 127 128 129 129 132 132 Freezing of meat 7.1 Freezing rate 7.2 Freezing systems 7.2.1 Air 7.3 Contact freezers 7.4 Cryogenic freezing 7.5 Freezing of specific products 7.5.1 Meat blocks 7.5.2 Beef quarters 7.5.3 Mutton carcasses 7.5.4 Offal 7.5.5 Small products 7.6 Tempering and crust freezing 7.6.1 Pork loin chopping 7.6.2 High speed ham slicing 137 137 140 140 142 144 145 145 145 146 146 147 149 149 150 viii Contents 7.7 7.8 10 7.6.3 High speed bacon slicing Conclusions References Thawing and tempering 8.1 Considerations 8.2 Quality and microbiological considerations 8.3 Thawing systems 8.3.1 Conduction 8.3.2 Electrical methods 8.3.3 Published thawing data for different meat cuts 8.3.4 Commercial practice 8.4 Tempering 8.4.1 Requirements for cutting and processing equipment 8.4.2 Requirements for prebreaking 8.4.3 Microwave tempering 8.4.4 Commercial practice 8.5 Conclusions 8.6 References 150 155 155 159 160 161 163 166 166 168 176 178 178 179 182 185 186 187 Transportation 9.1 Sea transport 9.2 Air transport 9.3 Overland transport 9.3.1 Types of refrigeration system 9.3.2 Observations of transport 9.3.3 Problems particular to local delivery vehicles 9.3.4 Design and operation of local distribution vehicles 9.4 Changes during transportation 9.5 Conclusions 9.6 References 191 191 193 193 194 195 197 Chilled and frozen storage 10.1 Storage life terms 10.2 Chilled storage 10.2.1 Unwrapped meat 10.2.2 Wrapped meat 10.2.3 Cooked products 10.3 Frozen storage 10.3.1 Oxidative rancidity 10.3.2 Prefreezing treatment 10.3.3 Freezing process 10.3.4 During frozen storage 207 207 208 209 211 214 216 216 218 220 221 198 202 204 204 Contents 10.4 Types of storage room 10.4.1 Bulk storage rooms 10.4.2 Controlled atmosphere storage rooms 10.4.3 Jacketed cold stores Conclusions References 224 224 225 225 225 226 Chilled and frozen retail display 11.1 Chilled display of wrapped meat and meat products 11.1.1 Factors affecting display life 11.1.2 Layout of chilled cabinet 11.1.3 Air curtain 11.1.4 Cabinet development 11.1.5 Computer modelling 11.1.6 Store conditions 11.2 Retail display of unwrapped meat and delicatessen products 11.2.1 Types of cabinet 11.2.2 Appearance changes 11.2.3 Effects of environmental conditions 11.3 Retail display of frozen wrapped meat 11.3.1 Factors controlling display life 11.4 Overall cabinet design 11.4.1 Air circulation and temperatures 11.4.2 Effect of doors and lids 11.4.3 Effect of radiant heat 11.4.4 Measurement methods 11.5 Conclusions 11.6 References 231 231 232 233 234 235 236 236 10.5 10.6 11 12 ix Consumer handling 12.1 Consumer attitudes to food poisoning 12.2 Shopping habits and transport from retail store to the home 12.3 Refrigerated storage in the home 12.4 Temperatures in domestic food storage 12.5 Performance testing of domestic refrigerators 12.5.1 Performance of empty appliances 12.5.2 Performance of loaded appliances 12.5.3 Effect of loading with warm (20 °C) food products 12.5.4 Effect of door openings 12.6 Performance testing of domestic freezers 12.7 Conclusions 12.8 References 237 238 238 239 241 241 244 245 246 247 247 248 249 251 252 252 255 256 262 263 263 264 264 265 267 269 x Contents Part Process control 13 Thermophysical properties of meat 13.1 Chilling 13.1.1 Thermal conductivity 13.1.2 Specific heat 13.1.3 Enthalpies 13.2 Freezing, thawing and tempering 13.2.1 Ice content 13.2.2 Heat extraction 13.2.3 Thermal conductivity 13.2.4 Density 13.3 Mathematical models 13.4 Conclusions 13.5 References 273 274 274 274 276 277 277 277 278 280 280 280 281 14 Temperature measurement 14.1 Instrumentation 14.1.1 Hand-held digital thermometers 14.1.2 Temperature recorders 14.1.3 Time–temperature indicators 14.2 Calibration 14.3 Measuring temperature data 14.3.1 Contact non-destructive methods 14.3.2 Non-contact non-destructive methods 14.3.3 Contact destructive methods 14.3.4 Storage 14.3.5 Distribution 14.3.6 Retail 14.4 Interpreting temperature data 14.4.1 Example 14.4.2 Example 14.5 Conclusions 14.6 References 283 284 284 285 288 289 289 290 290 292 294 295 296 298 298 299 301 302 15 Specifying, designing and optimising refrigeration systems 15.1 Process specification 15.1.1 Throughput 15.1.2 Temperature requirements 15.1.3 Weight loss 15.1.4 Future use 15.1.5 Plant layout 15.2 Engineering specification 15.2.1 Environmental conditions 15.2.2 Room size 303 303 304 304 304 305 305 306 307 308 332 Meat refrigeration Table 16.11 Examples of commercial cooling of meat slurries and soups in the UK Cooling method In ambient at 23 °C in 0.6 m3 vats In 0.6 m3 vats with cold water jacket then ambient at 21 °C In 38 cm diameter pans in chill room at to °C In 35 cm deep bucket at 20 °C for h then °C Depth of slurry (cm) Cooling time Temperature (°C) To 20 °C (h) Total (h) Initial Final 50 – 16 99 64 50 – 14 99 38 17 9.8 16 93 12 30 17.5 18 55 18 Source: James, 1990c 1100 kg batches of meat sauce could be cooled from 85 to 10 °C in less than 30 using a vacuum cooling system When a conventional blast air system was used the cooling time achieved was related to the product depth and even when the depth had been reduced to 70 mm the cooling time was in excess of 6.5 h 16.4 Process cooling Traditionally, ice has been added to meat mixtures during mixing and grinding to maintain their temperature Liquid nitrogen (LN2) can also be used to maintain the temperature of meat during mixing thus increasing the extraction of soluble muscle proteins LN2 or CO2 can also be used to chill restructured meat during mixing and cutting to -3 °C in approximately 10 to 15 Jowls and bacon fat in 1400 kg batches can be mixed and cooled from 7.3 to °C within 12 The system uses a cycle of 50 s LN2 and mixing then 15 s mixing only to allow temperature equalisation Cryogenic systems are also available to maintain temperatures during tumbling In cooked ham manufacture the use of liquid nitrogen was claimed to reduce meat dust during tumbling, substantially shorten the process time and improve hygiene 16.5 Cook–chill The term ‘cook–chill’ usually refers to a catering system where food is prepared, cooked and cooled in a central facility before being distributed to Secondary chilling of meat and meat products 333 the place where it will be reheated and consumed The term is equally applicable to the system of producing chilled ready meals for retail sale Sales of chilled ready meals reached £973m in the UK in 2001 (www.chilledfood.org) and continue to rise Within this market growth there is a strong move towards greater variety, with ethnic meals showing the fastest increase This has meant that more meals than ever before are being produced by manufacturing facilities operating cook–chill systems, using a wide range of production methods and equipment 16.5.1 Cook–chill guidelines Cook–chill systems are normally used to supply food in institutional (hospitals, schools, canteens, etc.) catering operations Normally the food is cooked and cooled under near industrial conditions It is stored and transported to the institution under refrigeration and reheated (not cooked) before serving One of the key elements to a successful cook–chill operation is the strict monitoring and control of temperature throughout Cooking rarely eliminates all food poisoning organisms and a number survive as spores that will germinate and grow if cooling rates are slow In the UK the Department of Health Cook–chill Guidelines published in 1989 recommend maximum cooling regimes and the use of special equipment to rapidly reduce product temperatures after cooking Many other countries in Europe have similar guidelines or recommendations for the cooling of cooked products (Table 16.12) The UK Guidelines recommend that joints of meat or packs of food should not exceed 2.5 kg or 100 mm in thickness or height It is also advised that containers have lids to help prevent contamination and to minimise dehydration during cooling The Guidelines also state that the actual chilling process should commence as soon as possible after completion of cooking and certainly within 30 of leaving the cooking process (this is to allow for portioning of meals) Smaller portions (less than 50 mm deep) should be chilled to between and °C within 90 and larger portions Table 16.12 Chilling time requirements for cooked foods in different countries Country Chilling times Chilling rate (°C/min) Storage temperature (°C) Denmark France Germany from 65 °C to 10 °C in hours from 70 °C to 10 °C in hours from 80 °C to 15 °C in hours (from 15 °C to °C in 24 hours) from 80 °C to °C in hours from 70 °C to °C in 1.5 hours 0.31 0.50 0.54 [...]... Meat Conference, American Meat Science Association 33 47–53 gill c o (1982), Microbial interaction with meats, in Brown MH, Meat Microbiology, London, Applied Science 225–264 gill c o (1983), Meat spoilage and evaluation of the potential storage life of fresh meat, J Food Protection, 46(5) 444–452 gill c o (1984), Prevention of early spoilage of livers, Proceedings of the 30th European Meeting of Meat. .. 341 15.3 15.4 15.5 16 xi Part 1 Refrigeration and meat quality 1 Microbiology of refrigerated meat There are many pertinent texts on the microbiology of meats The purpose of this chapter is to examine briefly the types of micro-organisms and conditions that are of interest in relation to the refrigeration of meat and meat products In a perfect world, meat would be completely free of pathogenic (food... production in meat refrigeration The quality of fresh meat exposed for retail sale is initially judged on its appearance The presence of exudate or ‘drip’, which accumulates in the container of prepackaged meat or in trays or dishes of unwrapped meat, substantially reduces its sales appeal (Malton and James, 1983) Drip can be referred to by a number of different names including ‘purge loss’, press loss’... spoilage organisms limit the shelf-life of meat The spoilage bacteria of meats stored in air under chill conditions include species of Pseudomonas, Brochothrix and Acinetobacter/Moraxella In general, there is little difference in the microbial spoilage of beef, lamb, pork and other meat derived from mammals (Varnam and Sutherland, 1995) 4 Meat refrigeration Meat is considered spoiled by bacteria when... on the microbiology of meat, in Cutting CL, Meat Chilling: Why and How? Meat Research Institute Symposium No 2, 2.1–2.6 leistner l and rödel w (1976), Inhibition of microorganisms in food by water activity, in Skinner FA and Hugo WB, Inhibition and Inactivation of Vegetative 18 Meat refrigeration Microbes, Society for Applied Bacteriology, Symposium Series No 5, London, Academic Press, 219–237 lepovetsky... chilled beef II Cooling and storage in the meatworks, Austral Council Sci Industr Res Bull, 129 68 shaw b g (1972), The effect of temperature and relative humidity on the microbiological quality of carcass meat, in Cutting CL, Meat Chilling: Why and How? Meat Research Institute Symp No 2, 7.1–7.10 shaw b g, mackey b m and roberts t a (1986), Microbiological aspects of meat chilling – an update, Recent advances... Measurement in Meat, Poultry and Fish Products, Advances in Meat Research Series, Volume 9, UK, Blackie Academic & Professional, Chapter 14, 359–403 taylor a a, shaw b g and macdougall d b (1980), Hot deboning beef with and without electrical stimulation, Meat Sci, 5 109–123 thornton h (1951), The aetiology of bone-taint, Brit Vet J, 107 371 varnam a h and sutherland j p (1995), Meat and Meat Products,... producing meat with less lactic acid and a relatively high ultimate pH, this gives the meat a dark, firm, dry (DFD) appearance Alternative terms are ‘dark cutting’ and ‘high-pH meat The condition occurs in pork, beef and mutton, but is of little economic importance in the latter (Newton and Gill, 1981) DFD meat provides conditions that are more favourable for microbial growth than in normal meat The... effects to the meat Animals subjected to severe exhaustion shortly before slaughter use up their glycogen reserves thus less lactic acid is formed producing high pH (6.0–6.5) dark meat, often described as dark, firm and dry (DFD) meat DFD problems can occur in pork, mutton, veal and beef By convention all pork above pH 6.0/6.2 is classified as DFD meat (Honikel, 1990) Drip losses from DFD meat are less... recommendation to operate meat chillers between 85–95% The actual RH used will depend, of course, upon the air speed, the type of meat, the length of storage required and the temperature of storage 1.2 Other considerations Legislation and recommendations for cooling of meat are believed to be based on clear microbiological criteria However, there are a lack of data Microbiology of refrigerated meat 13 to support