《肉制品冷冻技术》（英文版） Part 6 TThe cold chain from carcass to consumer

Part 2 TThe cold chain from carcass to consumer

Part 2 The cold chain from carcass to consumer

Primary chilling of red meat 6.1 Introduction The increased application of temperature legislation in many countries. coupled with economic requirements to maximise throughput, minimise weight loss and operate refrigeration systems in the most efficient manner, has created a very large demand for process design data on all aspects of carcass chilling Concurrently there has been a growing realisation of the importance of chilling rate on meat saleability, in terms of drip potential (see Chapter 2), appearance(see Chapter 4), and eating quality, particu- larly texture(see Chapter 3). EU temperature legislation governs the chilling of beef, pork and lamb for the majority of abattoirs within the community. The only derogations are for very small abattoirs and for retail shops cutting meat for direct sale to the final consumer. The EC legislation does not define a chilling time, only a maximum final meat temperature of 7C before transport or Abattoir management and refrigeration contractors require reliable design data, relating processing variables to chilling time and weight loss, so that they can specify and design carcass cooling systems to meet differ ng requirements To optimise fully such systems, knowledge is also required of the product heat load, and its variation with time, so that the refrigera tion machinery can be sized to achieve the required throughput It is also important that the industry is made aware of a growing number of alternatives to conventional batch air chilling systems. Many of the alter native systems offer significant advantages in terms of increased through- put, lower costs and increased product quality

6 Primary chilling of red meat 6.1 Introduction The increased application of temperature legislation in many countries, coupled with economic requirements to maximise throughput, minimise weight loss and operate refrigeration systems in the most efficient manner, has created a very large demand for process design data on all aspects of carcass chilling. Concurrently there has been a growing realisation of the importance of chilling rate on meat saleability, in terms of drip potential (see Chapter 2), appearance (see Chapter 4), and eating quality, particu￾larly texture (see Chapter 3). EU temperature legislation governs the chilling of beef, pork and lamb for the majority of abattoirs within the community. The only derogations are for very small abattoirs and for retail shops cutting meat for direct sale to the final consumer. The EC legislation does not define a chilling time, only a maximum final meat temperature of 7 °C before transport or cutting. Abattoir management and refrigeration contractors require reliable design data, relating processing variables to chilling time and weight loss, so that they can specify and design carcass cooling systems to meet differ￾ing requirements.To optimise fully such systems, knowledge is also required of the product heat load, and its variation with time, so that the refrigera￾tion machinery can be sized to achieve the required throughput. It is also important that the industry is made aware of a growing number of alternatives to conventional batch air chilling systems. Many of the alter￾native systems offer significant advantages in terms of increased through￾put, lower costs and increased product quality

100 Meat refrigeration 6.2 Conventional chilling The majority of carcass meat is chilled in conventional chill rooms nomi nally operating at one or sometimes two conditions during the chilling cycle Most of the factors that control the chilling process are common to all species and are covered in the following section on beef. Specific consid- erations for sheepmeat, pork and offal are outlined in their respective sections. 6.2.1 Beef This section brings together design data on many aspects of the chilling of beef sides. Effects of environmental, carcass and operational variables on the rate of chilling and evaporative weight loss in single stage air chilling systems are described in detail. Data are also presented on the rate of heat release from sides that are encountered in these cooling operations Using conventional single stage chilling regimes it is evident that only relatively light(<105 kg), lean beef sides can be cooled to 7C in the deep leg during a 24 h operating cycle, whilst evaporative losses are of the order of 2% Despite the general absence of specific regulations for chilling time, the time required to cool a side to a specified maximum temperature is the most important commercial factor determining the cost and operation of a cooling system. If sides cannot be chilled within 18h, which is the time avail able in one day, making allowance for loading, unloading and cleaning, they will probably remain in chill for a further 24 h. Chilling facilities will then have to be twice as large, with considerably increased capital investment and running costs. Some investigations on the continuous chilling of beef (Drumm et al., 1992a, b) have been carried out but such systems are not widely used Increasing attention is now being paid to the reduction in energy con sumption, but it has been shown that in commercial chilling operations the cost of evaporative weight loss in beef sides(Collett and Gigiel, 1986)are at least an order of magnitude higher than the energy costs. Major investigations to provide such data have been carried out at Food Refrigeration and Process Engineering Research Centre(FRPERC) Langford(formerly the Meat Research Institute)(Bailey and Cox, 1976; Cox and Bailey, 1978)and at the National Mechanical Engineering Research Institute, Pretoria(Kerens and Visser, 1978; Kerens, 1981). Pub- lished information from these investigations and others has been brought together in this section together with some unpublished material 6.2.1.1 Effect of environmental and carcass variables on cooling rate Air temperature, air velocity, and to a limited extent, relative humidity, are the environmental factors that affect the cooling time of beef sides. Cooling rate will also be a function of the weight and fat cover of a given side

6.2 Conventional chilling The majority of carcass meat is chilled in conventional chill rooms nomi￾nally operating at one or sometimes two conditions during the chilling cycle. Most of the factors that control the chilling process are common to all species and are covered in the following section on beef. Specific consid￾erations for sheepmeat, pork and offal are outlined in their respective sections. 6.2.1 Beef This section brings together design data on many aspects of the chilling of beef sides. Effects of environmental, carcass and operational variables on the rate of chilling and evaporative weight loss in single stage air chilling systems are described in detail. Data are also presented on the rate of heat release from sides that are encountered in these cooling operations. Using conventional single stage chilling regimes it is evident that only relatively light (<105 kg), lean beef sides can be cooled to 7 °C in the deep leg during a 24 h operating cycle, whilst evaporative losses are of the order of 2%. Despite the general absence of specific regulations for chilling time, the time required to cool a side to a specified maximum temperature is the most important commercial factor determining the cost and operation of a cooling system. If sides cannot be chilled within 18h, which is the time avail￾able in one day, making allowance for loading, unloading and cleaning, they will probably remain in chill for a further 24h. Chilling facilities will then have to be twice as large, with considerably increased capital investment and running costs. Some investigations on the continuous chilling of beef (Drumm et al., 1992a,b) have been carried out but such systems are not widely used. Increasing attention is now being paid to the reduction in energy con￾sumption, but it has been shown that in commercial chilling operations the cost of evaporative weight loss in beef sides (Collett and Gigiel, 1986) are at least an order of magnitude higher than the energy costs. Major investigations to provide such data have been carried out at Food Refrigeration and Process Engineering Research Centre (FRPERC), Langford (formerly the Meat Research Institute) (Bailey and Cox, 1976; Cox and Bailey, 1978) and at the National Mechanical Engineering Research Institute, Pretoria (Kerens and Visser, 1978; Kerens, 1981). Pub￾lished information from these investigations and others has been brought together in this section together with some unpublished material. 6.2.1.1 Effect of environmental and carcass variables on cooling rate Air temperature, air velocity, and to a limited extent, relative humidity, are the environmental factors that affect the cooling time of beef sides. Cooling rate will also be a function of the weight and fat cover of a given side. 100 Meat refrigeration

Primary chilling of red meat 101 6.2.1.1.1 Air temperature The results of the programme on beef chilling carried out at Langford clearly show the importance of air temperature on cooling time( Bailey and Cox, 1976). For ease of use the results of the investigations have been pre- sented as four plots of the logarithm of temperature against time covering wide range of side weights(100-220kg)and air velocities(0.5-3.0ms") Data for the slowest cooling area of the side, which was located by insert ing a probe into the centre of the thickest section of the leg, are Fig 6.1 and can therefore be used to determine the environmental condi tions required to attain a desired cooling time when a maximum final tem- perature has been specified Potential surface freezing problems can then be evaluated from the surface temperature plots(Figs. 6.2 and 6.3). These conjunction with the deep M. longissimus dorsi data(Fig. 6. 4) also identify toughening problems and the possible requirement for electrical stimulatio Cooling in air at a constant 4C, compared with 0'C, at 3ms wil crease the time to reach 7C in the deep leg of a 100kg side from 20.3 to 277h(a 36%increase). At 0.5ms, the time for a 220kg side to reach 7C will increase from 45.9 to 683h(a 49% increase). In systems designed to produce fully chilled sides, with average meat temperatures of 2-4C, the requirement for low air temperatures becomes even more important because of the small meat/air temperature difference at the end of the process. + Approximate average for British abattoirs 十哪四32232230 05105002 Time post-mortem ig. 6.1 Relationship between deep longissimus dorsi temperature and cooling time for beef sides(source: Bailey and Cox, 1976)

6.2.1.1.1 Air temperature The results of the programme on beef chilling carried out at Langford clearly show the importance of air temperature on cooling time (Bailey and Cox, 1976). For ease of use the results of the investigations have been pre￾sented as four plots of the logarithm of temperature against time covering a wide range of side weights (100–220 kg) and air velocities (0.5–3.0 ms-1 ). Data for the slowest cooling area of the side, which was located by insert￾ing a probe into the centre of the thickest section of the leg, are shown in Fig. 6.1 and can therefore be used to determine the environmental condi￾tions required to attain a desired cooling time when a maximum final tem￾perature has been specified. Potential surface freezing problems can then be evaluated from the surface temperature plots (Figs. 6.2 and 6.3). These in conjunction with the deep M. longissimus dorsi data (Fig. 6.4) also identify toughening problems and the possible requirement for electrical stimulation. Cooling in air at a constant 4°C, compared with 0 °C, at 3m s-1 will increase the time to reach 7 °C in the deep leg of a 100kg side from 20.3 to 27.7 h (a 36% increase). At 0.5 ms-1 , the time for a 220 kg side to reach 7 °C will increase from 45.9 to 68.3 h (a 49% increase). In systems designed to produce fully chilled sides, with average meat temperatures of 2–4 °C, the requirement for low air temperatures becomes even more important because of the small meat/air temperature difference at the end of the process. Primary chilling of red meat 101 38·5 38·5 38·5 35 35 35 30 30 30 25 25 25 20 20 20 15 15 15 10 10 7 5 4 3 7 10 2 1 5 9 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 0·01 0·02 0·03 0·04 0·05 0·06 0·07 0·08 0·09 0·1 0·2 0·3 0·4 0·5 0·6 0·7 0·8 0·9 1·0 0·5 0·5 0·5 Y 1 1 3 2 2 1 0·5 3 21 3 Air speed (m s 3 2 –1) Time post-mortem (h) Deep long. dorsi temperature (°C) Chiller air temperature (°C) 840 Side weights 100 140 180 220 Approximate average for British abattoirs kg Fig. 6.1 Relationship between deep longissimus dorsi temperature and cooling time for beef sides (source: Bailey and Cox, 1976)

Side weights kg 40--Approximate average for British abattoirs e品a Air speed(m s-)→32 Time post-mortem(h) Fig. 6.2 Relationship between deep leg temperature and cooling time for beef sides(source: Bailey and Cox, 1976) Side weights 140--Approximate average for British abattoirs 18- g2巴E28o8E0 Air speed(m.)→3232 0.02 Time post-mortem(h) Fig 6.3 Relationship between surface longissimus dorsi temperature and cooling time for beef sides(source: Bailey and Cox, 1976)

38·5 35 30 25 20 15 10 7 5 4 3 2 1 38·5 35 30 25 20 15 10 7 5 38·5 35 30 25 20 15 10 9 0 8 16 24 32 40 48 56 64 72 80 88 96 104 0·01 0·02 0·03 0·04 0·05 0·06 0·07 0·08 0·09 0·1 0·2 0·3 0·4 0·5 0·6 0·7 0·8 0·9 1·0 0·5 0·5 0·5 Y 1 1 3 2 2 0·5 1 3 2 1 3 2 3 Air speed (m s–1) Time post-mortem (h) Deep leg temperature (°C) Chiller air temperature (°C) 8 4 0 Side weights kg 100 140 180 220 Approximate average for British abattoirs Fig. 6.2 Relationship between deep leg temperature and cooling time for beef sides (source: Bailey and Cox, 1976). 38·5 38·5 38·5 35 35 30 30 25 25 20 20 15 15 10 7 10 35 30 25 20 15 10 7 5 4 3 2 1 5 9 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 0·01 0·02 0·03 0·04 0·05 0·06 0·07 0·08 0·09 0·1 0·2 0·3 0·4 0·5 0·6 0·7 0·8 0·9 1·0 0·5 0·5 0·5 Y 1 2 2 1 1 0·5 3 2 1 3 3 Air speed (m s 3 2 –1) Time post-mortem (h) Surface long. dorsi temperature (°C) Chiller air temperature (°C) 840 Side weights kg 100 140 180 220 Approximate average for British abattoirs Fig. 6.3 Relationship between surface longissimus dorsi temperature and cooling time for beef sides (source: Bailey and Cox, 1976)