Consumer handling Since the mid-1980s there has been a considerable increase in legislation defining maximum temperatures during the production, distribution and retailing of chilled food. However, as soon as the food is purchased by the consumer, it is outside of any of these legislative requirements. Increasingly food poisoning incidents have been found to be due to mishandling of food in the home with insufficient refrigeration or cooling being the most fre uent factor causing disease(WHO, 1992). Of the 1562 cases of food poi- soning reported during 1986-1988, 970(62%)were caused in the home. Consumer handling of products may not be as intended or envisaged by the manufacturer. Many chilled products are purchased on the basis of the "fresh image, but then frozen at home(Brown, 1992) After a chilled or frozen product is removed from a retail display cabinet it is outside a refrigerated environment whilst it is carried around the store and then transported home for further storage. In the home it may be left in ambient conditions or stored in the refrigerator/freezer until required. There are few published data on consumers'attitudes to chilled food and their handling procedures in the home. The majority of the data quoted here have been obtained from a survey of 252 households which was funded by the Ministry of Agriculture Fisheries and Food(MAFF)in the UK(Evans et aL., 1991). As part of the survey, participants were asked questions to ssess their attitude to food poisoning, shopping habits and the length of ime they stored chilled foods in the home Monitoring was then carried out to determine the length of time and temperature foods were stored at in the home. These data were augmented with experimental data from labo- ratory studies on the performance of refrigerators and temperature changes during transportation to the home
12 Consumer handling Since the mid-1980s there has been a considerable increase in legislation defining maximum temperatures during the production, distribution and retailing of chilled food. However, as soon as the food is purchased by the consumer, it is outside of any of these legislative requirements. Increasingly food poisoning incidents have been found to be due to mishandling of food in the home with insufficient refrigeration or cooling being the most frequent factor causing disease (WHO, 1992). Of the 1562 cases of food poisoning reported during 1986–1988, 970 (62%) were caused in the home. Consumer handling of products may not be as intended or envisaged by the manufacturer. Many chilled products are purchased on the basis of the ‘fresh image’, but then frozen at home (Brown, 1992). After a chilled or frozen product is removed from a retail display cabinet it is outside a refrigerated environment whilst it is carried around the store and then transported home for further storage. In the home it may be left in ambient conditions or stored in the refrigerator/freezer until required. There are few published data on consumers’ attitudes to chilled food and their handling procedures in the home.The majority of the data quoted here have been obtained from a survey of 252 households which was funded by the Ministry of Agriculture Fisheries and Food (MAFF) in the UK (Evans et al., 1991). As part of the survey, participants were asked questions to assess their attitude to food poisoning, shopping habits and the length of time they stored chilled foods in the home. Monitoring was then carried out to determine the length of time and temperature foods were stored at in the home. These data were augmented with experimental data from laboratory studies on the performance of refrigerators and temperature changes during transportation to the home
252 Meat refrigeration Bacon Sausages Cook-chill foods Me Pouitry-raw 0102030405060708090100110 Number of occurrences Fig 12.1 Meat products considered a food poisoning risk(source: Evans et al. 1991) 12.1 Consumer attitudes to food poisoning In the survey consumers were initially asked about their concern about food poisoning. The greatest number of participants (56.7%) were either only slightly concerned or not at all concerned about food poisoning. However, 31.7% of participants were concerned or very concerned about food poi soning(answers were restricted to concern about food from shops and did not include concern about food poisoning due to restaurant or fast food type meals or food) When asked to name foods that they considered might constitute a food poisoning risk most of the respondents(73%)considered poultry to be a problem. Raw poultry was considered to be a greater risk than cooked poultry Meat was also considered likely to cause food poisoning with 66.7% of participants mentioning either raw or cooked meat as a potential problem(Fig. 12.1) 12.2 Shopping habits and transport from retail store to e nte The frequency of shopping governs the length of time chilled food is stored n the home. Most consumers, 99. 2% of the survey population, shopped on at least one day a week and few(16.3%)less than twice a week for chilled food. The greatest number(33.7%) shopped for food 3-4 days per week, closely followed by 26.2% who shopped 5-7 days per week and 23.8% who shopped on two days. Generally shopping was divided into trips for large quantities(defined as greater than one bag)and small amounts of food (less than one bag). The majority of households(84.5%)shopped for small quan tities of chilled food on a variable basis as required
12.1 Consumer attitudes to food poisoning In the survey consumers were initially asked about their concern about food poisoning. The greatest number of participants (56.7%) were either only slightly concerned or not at all concerned about food poisoning. However, 31.7% of participants were concerned or very concerned about food poisoning (answers were restricted to concern about food from shops and did not include concern about food poisoning due to restaurant or fast foodtype meals or food). When asked to name foods that they considered might constitute a food poisoning risk most of the respondents (73%) considered poultry to be a problem. Raw poultry was considered to be a greater risk than cooked poultry. Meat was also considered likely to cause food poisoning with 66.7% of participants mentioning either raw or cooked meat as a potential problem (Fig. 12.1). 12.2 Shopping habits and transport from retail store to the home The frequency of shopping governs the length of time chilled food is stored in the home. Most consumers, 99.2% of the survey population, shopped on at least one day a week and few (16.3%) less than twice a week for chilled food. The greatest number (33.7%) shopped for food 3–4 days per week, closely followed by 26.2% who shopped 5–7 days per week and 23.8% who shopped on two days. Generally shopping was divided into trips for large quantities (defined as greater than one bag) and small amounts of food (less than one bag).The majority of households (84.5%) shopped for small quantities of chilled food on a variable basis, as required. 252 Meat refrigeration Bacon Sausages Pies Cook-chill foods Pâté Meat – raw Poultry – cooked Meat – cooked Poultry– raw 0 10 20 30 40 50 60 70 80 90 100 110 Number of occurrences Fig. 12.1 Meat products considered a food poisoning risk (source: Evans et al., 1991)
Consumer handling 253 Most participants in the survey carried out their main shopping between 1 and 5 miles from their homes and few householders travelled more than 5 miles to shop. Most people(85.3%)used a car to transport their main hopping home. Small quantities of food were generally bought close to the home, reflecting the availability of shops in the towns surveyed. Most house holders(87.6%)who bought small quantities of food transported it home either on foot or by car. Unprotected chilled food will warm up during transportation. Survey results showed that consumers took on average 43 min to bring meat, fish or dairy items home from the shops and place them in a refrigerator. The greatest number of items were transported home and placed in a refriger ator within 13 min. Although most people bought food home well within 60min there were a number of items which took far longer to be bought home(up to 2 days )and placed in a refrigerator. Although insulated bags and boxes are widely sold, only a small per centage of consumers(12.7%)used them to transport some of their food home. The vast majority(87.3%)of people did not use any means of pro- tecting food from temperature gain during transportation Increases in product temperatures during transportation can be consid erable. In investigations, the temperatures of 19 different types of chilled product (including a variety of meat products) were monitored during a simulated journey from the supermarket to home (James and Evans, 1992a). One sample of each product was placed in a precooled insulated box containing eutectic ice packs and the second left loose in the boot of he car. The car was then driven home and the product removed and placed a domestic refrigerator after a total journey time of 1h. Additional investigations looked at 9 types of frozen product, including frozen chicken, meat pie, lasagne and pizza(Evans, 1994). Products were purchased and transported to the research Centre where the products were tempered and temperature sensors inserted into the geometric centre of each food and where possible a second sensor inserted just below the surface of the sample. The products were then refrozen to a temperature of ca.-25C and then transferred to a car where the above procedure was repeated. After a journey time of l h the products were placed in the freezer ection of a domestic refrigerator. The ambient temperature during both urneys ranged from 23 to 270 Initial product temperatures of the chilled meats measured when the food reached the car ranged from 4C to over 20'C(Table 12.1). Some of the meat product temperatures in samples placed in the boot rose to around 30C during the 1 h car journey whilst most of the samples placed in the insulated box cooled during the car journey except for a few at the top of the box which remained at their initial temperature. Product temperatures in the frozen foods were close to -25C when placed in the car. Temperatures of products placed in both the cold box and at ambient temperature rose during the l h journey. Temperatures of
Most participants in the survey carried out their main shopping between 1 and 5 miles from their homes and few householders travelled more than 5 miles to shop. Most people (85.3%) used a car to transport their main shopping home. Small quantities of food were generally bought close to the home, reflecting the availability of shops in the towns surveyed. Most householders (87.6%) who bought small quantities of food transported it home either on foot or by car. Unprotected chilled food will warm up during transportation. Survey results showed that consumers took on average 43 min to bring meat, fish or dairy items home from the shops and place them in a refrigerator. The greatest number of items were transported home and placed in a refrigerator within 13 min. Although most people bought food home well within 60 min there were a number of items which took far longer to be bought home (up to 2 days) and placed in a refrigerator. Although insulated bags and boxes are widely sold, only a small percentage of consumers (12.7%) used them to transport some of their food home. The vast majority (87.3%) of people did not use any means of protecting food from temperature gain during transportation. Increases in product temperatures during transportation can be considerable. In investigations, the temperatures of 19 different types of chilled product (including a variety of meat products) were monitored during a simulated journey from the supermarket to home (James and Evans, 1992a). One sample of each product was placed in a precooled insulated box containing eutectic ice packs and the second left loose in the boot of the car. The car was then driven home and the product removed and placed in a domestic refrigerator after a total journey time of 1 h. Additional investigations looked at 9 types of frozen product, including frozen chicken, meat pie, lasagne and pizza (Evans, 1994). Products were purchased and transported to the Research Centre where the products were tempered and temperature sensors inserted into the geometric centre of each food and where possible a second sensor inserted just below the surface of the sample. The products were then refrozen to a temperature of ca. -25 °C and then transferred to a car where the above procedure was repeated.After a journey time of 1 h the products were placed in the freezer section of a domestic refrigerator. The ambient temperature during both journeys ranged from 23 to 27 °C. Initial product temperatures of the chilled meats measured when the food reached the car ranged from 4 °C to over 20 °C (Table 12.1). Some of the meat product temperatures in samples placed in the boot rose to around 30 °C during the 1 h car journey whilst most of the samples placed in the insulated box cooled during the car journey except for a few at the top of the box which remained at their initial temperature. Product temperatures in the frozen foods were close to -25 °C when placed in the car. Temperatures of products placed in both the cold box and at ambient temperature rose during the 1 h journey. Temperatures of Consumer handling 253
254 Meat refrigeration Table 12.1 Maximum temperatures(C)measured in meat products after being transported for I h in the boot of a car without protection or within a cooled insulated container Product Unprotected Smoked ham Beef pie 954726 Lasagne Source: Evans et al. 1991 te centre Cool box pate surface Fig. 12.2 Temperature chasse prans te during domestic transportation(source chickens and meat pies placed at ambient temperature reached tempera- tures approaching 10C. Frozen meat products in the cold box kept below 10C for the period of the journey Thin sliced chilled products showed the highest temperature char luring transport, whereas temperature gains in thicker products such hicken and pate(Fig. 12.2)were smaller. A similar trend was seen with the frozen products. After being placed in the domestic refrigerator, warm hilled products required ca 5h before the temperature at the surface was educed below 7C.Warm' frozen products placed in a domestic freezer required at least 5 h to reduce centre product temperatures to below -15C Predictions made using a mathematical model that calculated bacterial growth from temperature/time relationships indicated that increases of up to 1.8 generations in bacterial numbers(Table 12.2) could occur in the chilled foods during this transport and domestic cooling phase. The model assumed that bacteria required a time to acclimatise to the change in tem perature(the lag phase)and that no acclimatisation had occurred during
chickens and meat pies placed at ambient temperature reached temperatures approaching 10°C. Frozen meat products in the cold box kept below -10 °C for the period of the journey. Thin sliced chilled products showed the highest temperature changes during transport, whereas temperature gains in thicker products such as chicken and pâté (Fig. 12.2) were smaller. A similar trend was seen with the frozen products. After being placed in the domestic refrigerator, ‘warm’ chilled products required ca. 5 h before the temperature at the surface was reduced below 7 °C. ‘Warm’ frozen products placed in a domestic freezer required at least 5 h to reduce centre product temperatures to below -15 °C. Predictions made using a mathematical model that calculated bacterial growth from temperature/time relationships indicated that increases of up to 1.8 generations in bacterial numbers (Table 12.2) could occur in the chilled foods during this transport and domestic cooling phase. The model assumed that bacteria required a time to acclimatise to the change in temperature (the lag phase) and that no acclimatisation had occurred during 254 Meat refrigeration Table 12.1 Maximum temperatures (°C) measured in meat products after being transported for 1 h in the boot of a car without protection or within a cooled insulated container Product Unprotected Cool box Minced beef 18 9 Sausage (raw) 28 15 Smoked ham 30 14 Beef pie 24 7 Sausage roll 28 12 Lasagne 21 6 Source: Evans et al., 1991. 0 60 120 180 240 300 360 Time (min) 0 5 10 15 20 25 30 Temperature (°C) Ambient pate centre Ambient pate surface Cool box pate centre Cool box pate surface ˆ ˆ ˆ ˆ ´ ´ ´ ´ Fig. 12.2 Temperature changes in paté during domestic transportation (source: Evans et al., 1991)
Consumer handling Table 12.2 Maximum temperature measured and increase in bacterial numbe in chilled foods during 1 h in car followed by 5h in a domestic refrigerator Product Conditions Maximun Pseudomonas temperature (generations) (generations) C Pate Ambient. car Cool box car <04 Chicken-raw Ambient. car 1.6 Cool box car Ambient. car 1.8 cooked Cool box car 344827 Prawns Ambient car 13 Cool box car 0.0 Source: Evans et al.. 1991 display. If this rather optimistic assumption was not made then up to 4.2 doublings of pseudomonas and growth of both salmonella and listeria were predicted. Only very small increases in bacterial numbers(<0. 4 genera- tions)were predicted in products transported in the insulated box, owing to the maintenance of lower product temperatures. Although it was unable to prevent bacterial growth, the cold box did ensure that bacterial growth was minimal and was substantially less than if transported in ambient conditions 12.3 Refrigerated storage in the home The length of time consumers store chilled foods after purchase will affect their safety. In the survey consumers thought that the majority of meat and meat products (raw meat, cooked meat, raw poultry, cooked poultry, pre pared meals, pizza/quiche, cold pies and sausages) would store well for 2 days. However, a number of people considered that these foods could be stored for more than 7 days and sometimes as long as 30 days. Most par ticipants thought that products such as bacon and pate could be stored for up to a week, although a few people considered that storage of up to 30 days was acceptable. Fresh fish was generally considered to store less well, ith most participants stating that they would only store fish for 1 day or less o The range in anticipated storage life for different food types varied con- derably Opinions on the storage lives of individual foods ranged from 0.5 o 7 days(range 6.5 days)for cold pies and sausages to between 0.5 to 30 days(range 29.5 days) for pate and bacon. The minimum storage life for all meats and meat products was either a quarter or half a day. A small number of householders thought that they could store chilled foods for periods of up to 30 days. Bacon and pate were both thought to be acceptable after this
display. If this rather optimistic assumption was not made then up to 4.2 doublings of pseudomonas and growth of both salmonella and listeria were predicted. Only very small increases in bacterial numbers (<0.4 generations) were predicted in products transported in the insulated box, owing to the maintenance of lower product temperatures. Although it was unable to prevent bacterial growth, the cold box did ensure that bacterial growth was minimal and was substantially less than if transported in ambient conditions. 12.3 Refrigerated storage in the home The length of time consumers store chilled foods after purchase will affect their safety. In the survey consumers thought that the majority of meat and meat products (raw meat, cooked meat, raw poultry, cooked poultry, prepared meals, pizza/quiche, cold pies and sausages) would store well for 2 days. However, a number of people considered that these foods could be stored for more than 7 days and sometimes as long as 30 days. Most participants thought that products such as bacon and pâté could be stored for up to a week, although a few people considered that storage of up to 30 days was acceptable. Fresh fish was generally considered to store less well, with most participants stating that they would only store fish for 1 day or less. The range in anticipated storage life for different food types varied considerably. Opinions on the storage lives of individual foods ranged from 0.5 to 7 days (range 6.5 days) for cold pies and sausages to between 0.5 to 30 days (range 29.5 days) for pâté and bacon. The minimum storage life for all meats and meat products was either a quarter or half a day.A small number of householders thought that they could store chilled foods for periods of up to 30 days. Bacon and pâté were both thought to be acceptable after this Consumer handling 255 Table 12.2 Maximum temperature measured and increase in bacterial numbers in chilled foods during 1 h in car followed by 5 h in a domestic refrigerator Product Conditions Maximum Pseudomonas Clostridium temperature (generations) (generations) (°C) Pâté Ambient, car 25 1.5 0.4 Cool box, car 13 <0.4 0.0 Chicken – raw Ambient, car 24 1.6 0.2 Cool box, car 4 0.0 0.0 Chicken – Ambient, car 28 1.8 0.7 cooked Cool box, car 12 0.0 0.0 Prawns Ambient, car 37 1.3 1.6 Cool box, car 14 0.0 0.0 Source: Evans et al., 1991