The changing customer – a comparison with previous research

In 1991 the Ministry for Agriculture, Fisheries and Food (MAFF) conducted a survey entitled “Consumer Handling of Refrigerated foods: A survey of time and temperature conditions”²³ which aimed to provide data on the way consumers handle refrigerated foods. The survey focused on:

 shopping patterns and habits of consumers;

 the perceived and actual storage lives of food once bought into the home;

 consumer awareness of food poisoning;

 how consumers stored foods in the home and at what temperatures food was being stored in domestic refrigerators; and

 the effects of refrigerator characteristics upon temperature performance of refrigerators.

This survey formed the basis for some of the questions within the recent WRAP research and where relevant a comparison has been made between the responses from the two surveys.

Which day do you usually carry out your main food shopping trip?

Comparison of the WRAP study against the 1991 MAFF study reveals that today’s consumers are less regimented about their shopping routine with 32% of people saying that their main shopping day varied vs. just 8% making this claim in 1991. Forty-six per cent of people today carry out their main shopping trip on a Thursday, Friday or Saturday, a drop of 13% since 1991; this is no doubt fuelled by longer store opening hours, Sunday trading and the availability of online shopping.

Approximately how long is it usually between completing the shop and unpacking your shopping for main food shopping trip/top up shopping?

Forty-five per cent of today’s consumers say it usually takes half an hour to get their main shopping home and unpacked vs. 96% of people making this claim in 1991. A further 48% of people spend between half an hour and two hours to get their main shopping home and unpacked vs. just 4% in 1991. For top up shopping, a higher number of people will spend between half an hour and an hour between completing the shopping and unpacking it, with 27% of people taking this long vs. just 5% in 1991.

How do you make the journey for large amounts of food and for small amounts of food/top up shopping?

Results from the WRAP survey reveal a slightly higher reliance on the car as the method of transport for carrying out the main shop with 90% of people using the car in 2009 vs. 83% in 1991. The significant difference is seen for the top up shopping with 33% more of today’s consumers using the car for this; a direct switch from using a bike or going on foot.

23 MAFF (1991) Consumer handling of refrigerated foods. A survey of time and temperature conditions. PBO 682, MAFF Publications

Reducing food waste through the chill chain 35

Where do you usually shop for … ?

Consumers today focus much more of their shop on the supermarket, and for the four products asked about in both studies showed a preference towards purchasing at the supermarket, namely eggs (+33%), fresh meat (+34%), cooked meat (+25%) and bacon (+18%).

Do you use a cool bag/box to bring refrigerated foods home?

The usage of a cool bag/box to bring food home from store has not increased with 13% claiming to do this both in 1991 and 2009.

When you’ve bought the following foods how long do you usually expect to be able to keep them (without freezing them)?

Opinion around expected storage life has altered significantly for some foods between 1991 and 2009. Across five comparable categories the expected shelf life has increased²⁴. Also of particular significance is the number of people who don’t know what they expect shelf life to be; the probable result of not knowing how long something will last for, is to err on the side of caution and throw it away. Comparison by category is made below (and charted in Figure 16):

 In 1991, 6.7% of people expected to store fresh meat for more than 4 days; in 2009 this has risen to 18.5%.

Those not knowing how long fresh meat should last have risen from 0.4% to 4.3%.

 For fresh fish, in 1991, 2.8% of people expected a shelf life of more than 4 days; in 2009 this has risen to 5.8%. A more significant change is that 22.6% in 2009 do not know what they expect the shelf life of fresh fish to be compared to 1.6% in 1991.

 In 1991, 29.4% of people expected to store cooked meats for more than 4 days, while in 2009 this number has risen to 55.3%. Those who don’t know what they expect shelf life to be have risen from 1.6% to 4.3%²⁵.

 Bacon was given an expected storage life of above 4 days by 59.5% of people in 1991, whereas in 2009 this number has risen to 74%. Those not knowing how long bacon should last have risen from 1.2% to 8.3%.

 In 1991, 7.5% of people expected to store chilled ready meals for more than 4 days, while in 2009 this number has risen to 32.4%. The chilled ready meal category is the only one where the percentage of people that don’t know what they expect shelf life to be has fallen from 7.5% to 4%.

Figure 16 Storage expectations for refrigerated foods: MAFF 1991 study compared to the WRAP 2009 study.

Comparison of Expectation of Storage Life of Selected Products: 1991 vs 2009 92.9

Fresh Meat Fresh Fish Cooked Meats Bacon Chilled Ready Meals

% of people

1991 2009

24 The increased use of MAP, for example, in the packing of fresh meat and fish and cooked meats together with greater shopping frequency could, in part, explain why expected storage life has increased for these products.

25 It should be noted that the MAFF survey in 1991 did not specifically distinguish between unopened and opened food. The comparison made here is therefore subject to a degree of subjectivity as the WRAP responses are for unopened food only. In addition, the 1991 survey examined cooked meat and cooked poultry as separate categories whereas the WRAP study examines only cooked meat (e.g. pre-packed sliced ham). It is unknown how respondents to the 1991 survey interpreted the term

‘cooked poultry’, we assume it’s likely to be as a home-made leftover than a pre-packed product and this has therefore been excluded from our analysis.

Reducing food waste through the chill chain 36

4.2 In-home fridge experiment

As an extension to the consumer survey, Campden BRI measured the temperatures of a selection of participants’

fridges over a period of time to establish at what actual temperatures domestic fridges are operating and how well the fridge is doing at keeping the food inside it cold²⁶.

4.2.1 Method summary

A representative selection of 50 consumer fridges were chosen during the survey work and temperatures were measured in each of these fridges in three locations, top, middle and bottom shelf. Temperatures were recorded at one minute intervals for a minimum of four days, which included two weekend days and two weekdays. The 50 households were chosen to represent a range of demographics, fridge types, fridge age, fridge make/model and geographical area (detail is given in Appendix 4). The temperatures were measured using miniature data loggers with an accuracy of better than 0.5°C (Logtag TREX 8).

4.2.2 Results

Figure 17 shows the range of domestic fridge air temperatures measured, suggesting that the majority of domestic refrigerators operate at a mean temperature of around 7°C. The data shows that a proportion of the fridges tested (14 fridges, 29% of the sample) were operating at mean fridge temperatures of 9°C or above.

Only 14 of the 48 fridges (29% of the sample) were found to be at mean temperatures of 5°C or less. With 34 fridges (70%) operating below 8°C. Higher temperatures may be the result of poor door seals, factors such as incorrect settings, overloading or congestion with ice. It may be beneficial to educate consumers regarding good practice, such as checking seals, regular cleaning, defrosting and not overloading.

Figure 17 Frequency distribution of mean domestic fridge temperatures (50 fridges, 3 temperature loggers per fridge).

0 1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 More

Mean Fridge Temperature (°C)

Frequency of Households

26 Unfortunately it was not thought practical to ask respondents to keep a diary of fridge use in order, for example, to determine the impact of loading the main shop in to the fridge, or of door opening.

Reducing food waste through the chill chain 37 Figure 18 shows the mean air temperatures measured in each part of the fridges over the entire duration of the trial. The warmest location was consistently the bottom 'salad crisper' compartment, with a mean temperature of 9.6°C. The mean temperature on the top shelf of the fridges was 5.9°C and the mean temperature at the central shelf was 4.7°C.

Figure 18 Mean temperatures in different parts of the fridge (50 fridges, 3 temperature loggers per fridge).

The centre (middle shelf) of the fridge was consistently found to be the coldest area. Figure 19 shows the range of fridge air temperatures measured at the centre, suggesting that the majority of domestic refrigerators (35%) operate at a mean temperature of around 5°C at their coldest point. However, it was also apparent that a significant proportion of the fridges tested (22 fridges, 45% of the sample) were operating at coldest mean fridge temperatures of 7°C or above.

Figure 19 Frequency distribution of mean domestic fridge temperatures at the middle in the fridge (50 fridges).

0 1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 More Mean temperature:Middle of fridge (°C)

Number of fridges 

Reducing food waste through the chill chain 38 Figure 20 shows how the mean temperature of the fridges tested varied with the age of the fridge. The results suggest a general trend that older fridges have higher mean air temperature than newer models; fridges between one and two years old showed mean fridge temperatures of 3.7°C compared with mean fridge temperatures of 6.4°C within fridges of 5+ years old. (NB, 70% of respondents to the consumer survey had fridges that were less than 5 years old). However, there does not appear to be a clear correlation between fridge performance and its age though an older fridge may have a poor distribution of temperature if it is not working correctly or if the door seals were damaged.

Figure 20 Variation of mean domestic fridge temperatures with age of fridge (50 fridges, 3 temperature loggers per fridge).

Figure 21 shows how mean fridge temperature was affected by fridge type. Fridge compartments at the bottom of the fridge-freezer combination showed slightly higher mean fridge air temperatures than both stand alone (larder) fridges and fridge freezers with the fridge compartment on top.

Figure 21 Variation of mean domestic fridge temperatures with fridge type (50 fridges, 3 temperature loggers per fridge).

Reducing food waste through the chill chain 39 Figure 22 shows how mean fridge air temperature was affected by fridge volume (size). No clear correlations are apparent between the size of the fridge and the mean temperatures measured during these tests.

Figure 22 Variation of mean domestic fridge temperatures with fridge volume (50 fridges, 3 temperature loggers per fridge).

4.2.3 Limitations of the study

Almost all fridges work on a vapour compression cycle. The cooling effect is generally controlled by a simple ‘on-off’ thermostat that switches on the compressor when the temperature is too high and then off when the temperature has reached a pre-determined level. As such, fridge air temperatures fluctuate and ‘cycle’.

It is important to note that depending on the temperature of food going into the fridge, its residency time, its density and its packaging the fridge air temperature will not necessarily directly correlate to product temperature.

Nor will product temperature fluctuate at the same speed or to the same extent as air temperature. This study was not designed to quantify product temperature changes and cannot suggest the extent to which product temperatures are affected by air temperatures and cycles. However it is obvious that at equilibrium the temperature of the food cannot be lower than the air temperature.

For this study, air temperature was measured in three locations within the fridge (top, middle and bottom). Also, although the measurements were conducted over a minimum of four days, it is possible that this four-day window may not have been a truly representative indication of actual fridge use.

Although not measured, through this experiment, food product temperatures are known to be dependent on many factors e.g. position of product within the fridge, external temperature, how full the fridge is and the temperature of the food when it is placed in the fridge.

If repeated, it would be useful to ask participants to keep a basic diary to record fridge usage during the time when the data loggers are in the fridge. This wouldn’t entail tracking every time the fridge door is opened but would record if, for example, the door is open for a longer period of time than usual (e.g. to clean the fridge or to unpack the shopping).