Reducing food waste through the chill chain

Part 1: Insights around the domestic refrigerator

Reducing food waste through the chill chain

An extensive study of consumer refrigerated food practices in the home and experimental measurements of refrigerated food temperatures during their transit from the retail store to the domestic fridge.

Project code: RSC007-003 Research date: April-November 2009 Date: August 2010

WRAP helps individuals, businesses and local authorities to reduce waste and recycle more, making better use of resources and helping to tackle climate change.

Written by: R. M. George, P. J. Burgess and R. D. Thorn (Campden BRI)

Front cover photography: Consumer fridge, taken as part of this research WRAP and (Campden BRI) believe the content of this report to be correct as at the date of writing. However, factors such as prices, levels of recycled content and regulatory requirements are subject to change and users of the report should check with their suppliers to confirm the current situation. In addition, care should be taken in using any of the cost information provided as it is based upon numerous project-specific assumptions (such as scale, location, tender context, etc.). The report does not claim to be exhaustive, nor does it claim to cover all relevant products and specifications available on the market. While steps have been taken to ensure accuracy, WRAP cannot accept responsibility or be held liable to any person for any loss or damage arising out of or in connection with this information being inaccurate, incomplete or misleading. It is the responsibility of the potential user of a material or product to consult with the supplier or manufacturer and ascertain whether a particular product will satisfy their specific requirements. The listing or featuring of a particular product or company does not constitute an endorsement by WRAP and WRAP cannot guarantee the performance of individual products or materials. This material is copyrighted. It may be reproduced free of charge subject to the material being accurate and not used in a misleading context. The source of the material must be identified and the copyright status acknowledged. This material must not be used to endorse or used to suggest WRAP’s endorsement of a commercial product or service. For more detail, please refer to WRAP’s Terms & Conditions on its web site: www.WRAP.org.uk

Reducing food waste through the chill chain 3

Executive summary Keeping refrigerated food1 cold (typically between 0oC and 5oC) is important to ensure the safety and quality of the food up to the end of its stated shelf life. From the point of manufacture, through distribution and in the display cabinets in-store, there are strict guidelines for the control of temperature. It is important that consumers take similar care from the point of purchase, through transportation home and in the domestic refrigerator. It is this latter part of the chill chain that is the focus of this study (Figure E1).

Figure E1 Summary of the domestic chill chain

Helping consumers to better understand the importance of storing food correctly could make a significant contribution to reducing the 2.9 million tonnes of food and drink that is thrown away before ever being cooked or served ("not used in time"). WRAP research2 has shown that 255,000 tonnes of food is thrown away before it has even reached its ‘use by’ or ‘best before’ date, and much of this could have been avoided if the food had been stored correctly, including at the right temperature. This project has sought to understand domestic refrigerated food storage and is comprised of four elements: Store to home assessment. Consumer survey and in-home fridge temperature experiment. Controlled domestic fridge temperature study. Domestic fridge thermometer evaluation.

The main aims of the study are: To generate consumer insights that will inform a behavioural change campaign, for example, through Love

Food Hate Waste (www.lovefoodhatewaste.com), focusing on increasing consumer understanding of the importance of good temperature control through the domestic chill chain and how consumers can ensure they are keeping food at the right temperature e.g. using a fridge thermometer effectively. For maximum impact the messages would need to be reinforced by partners in the grocery and white goods sector.

To provide evidence to the refrigerator manufacturing industry that will enable them to consider new design features to make their temperature control features more evident to their consumers and easy for them to use.

Fridge air temperatures, rather than product temperatures, were recorded throughout this research. This reflects how consumers would measure fridge temperatures using most domestic thermometers. The key insights from this work are summarised below. Store to home assessment The 'store to home' assessment was conducted to quantify the changes in temperature within a range of refrigerated foods, that might occur after they had been purchased by the consumer from the retailer and during the transit home to the consumer’s own fridge. The temperature change in six different food products was monitored through three controlled tests and in three different bag types (an insulated bag (cool bag), woven bag and standard bag).

1 ‘Refrigerated food’ is used in this report to refer to all foods that are designed to be kept refrigerated for reasons related to safety or quality, plus any foods that benefit from being kept refrigerated (for example, fresh fruit that retains its quality for longer if kept refrigerated). 2 Household Food and Drink Waste in the UK, WRAP, 2009


The results from this work suggest that using insulated bags to bring refrigerated food home from the shops, particularly during warmer months, will help reduce the degree to which product temperatures may increase. The number of consumers now using ‘bags for life’ would suggest that this might not be a particularly difficult behaviour to adopt. In addition, consumers should be alerted to the magnitude of the food temperature rises that can occur during shopping and transport. Given the particularly good results for all bag types during the test designed to simulate shopping during colder months (when the period at the higher temperature was the shortest), it may be beneficial to remind all consumers, when in-store, to pack refrigerated and frozen items together where possible and transport chilled and frozen foods as quickly as possible to minimise the risk of food spoilage. Depending on the type of food, the bag used and the temperature regime employed to mimic different ‘store to home’ journeys, temperature rises of up to 11°C were observed. Following the temperature change phase of the test, the products were returned to the controlled temperature room and removed from the carrier bag, to simulate being stored in a domestic refrigerator. Data was logged during this cooling period, and it showed that some of the products took up to 15 hours to return to below 5°C with the chiller operating at 4.3°C. It is likely that this ‘recovery’ time would be longer in a domestic refrigerator due to the lower airflow and space limitations that mean that products are often stacked up or pushed close together. This finding underlines the importance of not allowing products to warm up significantly during shopping and transport. Consumer survey and in-home fridge experiment Several key insights were gained through the research which may contribute to food waste: A substantial number of respondents stated that they did not check the contents of the refrigerator before a

major shop (either thoroughly (32%) or briefly (39%)) with the implication that this may lead to unnecessary food purchases.

Only 13% of all respondents used a cool bag/box to bring refrigerated foods home. Overall, 45% of respondents stated that the usual time between completing the main grocery shop and unpacking was up to 30 minutes, with a further 23% stating this was between 30 minutes to one hour.

Many people are not storing foods in the fridge that will last much longer there, for example 78% do not store apples in the fridge and 36% don’t store carrots in the fridge. WRAP research3 has shown that storing apples and carrots in the fridge can maintain their quality and extend their in-home life, making it easier for consumers to eat the whole pack and avoid wasting any. In addition 29% don’t store eggs in the fridge, as recommended.

The storage of opened cheese was variable with just over a third of buyers (34%) storing the product in its original packaging in the fridge, and a further 40% in the fridge but in an alternative wrapping. Nearly a fifth (19%) stated that they decanted this item into an airtight container. The storage of cooked meats was similar to that of cheese in that 42% of buyers stored the product in its original packaging in the fridge, and a further 37% in the fridge but in an alternative wrapping. Just over 11% decanted opened/cooked meat into an airtight container.

42% disposed of unopened cooked meats occasionally while 38% occasionally disposed of unopened chilled ready meals. When it came to opened and partly consumed food the figures were unsurprisingly higher; cooked meats rose to 59% and cheese, chilled ready meals, apples and carrots were all disposed of occasionally by 40% of the survey population. A lack of knowledge about shelf life of certain foods or their optimum storage conditions may well be contributing to this (in addition to pack size for example).

It is encouraging that, unprompted, 79% of respondents correctly stated that the fridge should be run at between 0oC to 5oC4, although just over 10% of respondents did not provide a response, 4% said either -2oC or -1oC and 5% said 6oC. However, just a fifth had some way of measuring their fridge temperature (e.g. an integral temperature display or fridge thermometer).

Notably a significant proportion of the survey population (16%) agreed with the comment that fridge temperatures do not make much difference to how long food lasts.

The in-home temperature survey completed as part of this research shows that the majority of domestic refrigerators operate at a mean air temperature of around 7°C. It was apparent that a proportion of the fridges tested (14 fridges, 29% of the sample) were operating at mean air temperatures of 9°C or above. Only 14 of the 48 fridges (29% of the sample) were found to be at mean air temperatures of 5°C or less. With 34 fridges (70%) operating below 8°C.

3 Helping consumers reduce fruit and vegetable waste, WRAP, April 2008 4 http://www.eatwell.gov.uk/keepingfoodsafe/storing/#cat301168. Advice relates to air temperature.


The average air temperature reading across the whole survey population, as recorded by the interviewers, using the thermometers provided was 5.9oC. This would suggest that the majority of fridges in the UK are operating in a manner which should allow food to be stored at a safe temperature (assuming particularly sensitive foods are stored in the coldest part of the fridges). However, up to 30% of households may improve their fridge performance by reducing their fridge temperatures. Controlled domestic fridge temperature study The air temperature and humidity levels within six fridges were tested under laboratory controlled conditions (e.g. air temperature and humidity measurements, fridge loading, door opening and environmental conditions)5. The six fridges chosen for this test encompassed, as far as practicable, a range of makes, models and designs. 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’. During the experiment, the six fridges were set to provide a nominal fridge air temperature of 5°C and maintained an average (across a range of locations within each fridge) temperature distribution below 5oC. A wide variation of air temperatures were measured at different points in the cabinet. The fridges with glass shelves were better able to maintain a more consistent air temperature within the fridge and to minimise any rapid rise in air temperature than those with wire shelves. 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 assumed that, at equilibrium, the temperature of the food cannot be lower than the air temperature. For all but one of the models tested the temperature dial was not designed to correlate with the actual temperature nor was it clear whether turning the dial up would raise temperatures or visa versa. Ideally, given that temperatures are not consistent within fridges and the temperature fluctuations, consumers should monitor their fridge temperatures, using a fridge thermometer, on a regular basis and at a range of locations within the fridge. This will enable them to keep temperature sensitive foods in the coldest part of the fridge. In addition, awareness of such temperature variations, and advice on where to store specific foods (for maximum quality and safety) should be graphically represented inside the fridge cabinet. Fridges that clearly indicate their temperature to the consumer, for example, through an integral thermometer (where the reading is visible without opening the door) and alert them when the temperature rises beyond an acceptable level e.g. 8oC would help consumers ensure their fridge is operating at the right temperature. The humidity levels measured within the fridges showed that in general the interior of a fridge is quite a dry environment. In a fridge, humidity levels are generally lower than the surrounding environment as the moisture in the air condenses on the cooled surfaces within the fridge and then is drained away. These results re-emphasise the importance of wrapping food such as cheese and sliced meats in an air-tight container to prevent them drying out. Domestic fridge thermometer evaluation A separate study (undertaken for WRAP by Campden BRI) evaluated a wide range of domestic fridge thermometers available to the UK consumer. The results of this work are presented in a separate report6 with an overview of the results included in this report given the recommendation from this work to use a fridge thermometer in the home.

5 The experiments were not designed to align with ISO standards, which set out test methods for household refrigerating appliances, but to simulate a real life environment. Hence, the controlled domestic fridge study tests air temperature rather than product temperature as this is what the consumer will measure using most domestic thermometers. 6 A performance assessment of domestic fridge thermometers, WRAP, 2009.


The 18 different fridge thermometers tested were generally accurate, even the cheapest variants, though the development of a design specifically for fridge use (where the scale is at a suitable range) would minimise reader error. In conclusion, it would seem that there is scope to improve temperature control in the domestic chill chain. Key is improving consumer understanding of the importance of good temperature control and ensuring tools such as fridge thermometers are used effectively. Regularly monitoring fridge temperature in a range of locations and storing the most temperature sensitive foods in the coldest part of the fridge could deliver significant benefits. Recommendations

This study has generated a number of key observations regarding the consumer use of fridges and a series of recommendations across the supply chain that could be explored to help consumers keep what they buy at its best in the fridge and prevent food waste. These are summarised below: Food manufacturers Simplify the labelling of products with respect to storage conditions on-pack aiming for a common approach

whereby manufacturers should choose to label with a choice of two phrases relating to temperature, i.e. either “Keep Refrigerated”7 or “Store at 5°C maximum”. This is in line with CFA guidance8 and would help reiterate the correct fridge temperature (of below 5°C) and highlight which are temperature sensitive products.

Extend the use of reclosable packaging, particularly for products like cheese and cooked meat and, where possible, make it clear that the packaging is helping to keep the food fresh because the fridge is a dry environment.

Food retailers Increase the availability and visibility of tools such as fridge thermometers and ‘cool-bags’ in-store, for

example, by selling them in the refrigerated food aisles. Include tips and guidance, for example, at point of sale or incorporated into recipe card materials, highlighting

the importance of good temperature control. Increase consumers’ knowledge of the link between optimal storage, particularly in regard to keeping refrigerated food at the right temperature, and keeping food fresh. Such materials could also make consumers aware of humidity levels within the fridge and the importance of wrapping/reclosing opened packs or storing them in air-tight containers.

White goods manufacturers Investigate developing an industry standard for whether turning the dial up or down reduces or raises the

temperature or as a minimum make it clearer for any given fridge which direction produces a cooler or warmer temperature. It would be helpful if the industry could take steps to start producing fridges where the numbers on the dial reflect the temperature. In moving towards this objective it is recommended that higher numbers reflect higher temperatures.

Reinforce the importance of keeping the fridge at the right temperature, with tips on using a fridge thermometer and regularly measuring the temperature, for example, graphically within the fridge or within the manufacturer’s handbook.

Include illustrations, for example, graphically within the fridge or within the manufacturer’s handbook, of where the coldest part is likely to be together with guidance on which temperature sensitive foods should be stored there. Continue to increase the proportion of manufacturer handbooks available online and include a simple “one page” summary \ pull-out on-line and in hard copy of the relevant use and storage advice.

Develop point of sale material to highlight the importance of good temperature control, fridge humidity and using a fridge thermometer.

Increase the number of new fridges (even basic designs) that have an integral thermometer. The temperature indicator should ideally be visible to the consumer even when the door is closed. The suitability of integral alarms, that sound when the temperature rises above a certain level, could also be investigated.

7 From a manufacturing perspective, chilled food labelling of ‘keep refrigerated’ is taken to mean an 8°C maximum, targeting 5°C. In reality, most commercial chill chains will operate well towards the lower end of this regime. The larger temperature range reflects the fact that residency time in the supply chain is relatively short. Consumer facing messages should, however, only refer to a temperature range of 0-5°C. 8 Labelling of storage requirements on pack, CFA, 1996 (http://www.chilledfood.org/MEDIA/POSITION+STATEMENTS/temperature)


Fridge thermometer manufacturers Ensure all thermometers are sold with clear instructions for use e.g. what temperature the fridge should be

run at, good practice on how regularly the temperature should be measured and at how many locations in the fridge.

Develop thermometers that are specifically for fridge use and have a scale that is appropriate to the temperature range likely to be found in a domestic fridge; and is therefore easy to read.

White goods retailers Stock tools such as fridge thermometers and fridge door alarms alongside fridges. Include tips and guidance, for example, at point of sale, highlighting the importance of good temperature

control.

WRAP / FSA Update the survey of domestic refrigerator temperatures in the UK (e.g. as proposed under the FSA’s

‘Forward Evidence Plan’9. Use the Love Food Hate Waste (www.lovefoodhatewaste.com) campaign and Eatwell (www.eatwell.gov.uk) to

reinforce messages about: The importance of good temperature control in-home and between leaving the supermarket and home for

refrigerated foods e.g. minimising the time the food is outside a refrigerated environment and the fridge door is kept open etc.

The fact that fridges are not designed to have a consistent temperature throughout, providing good practice guidance for measuring fridge temperatures (how often and at what locations).

The likely humidity levels within refrigerators and the effect on food products e.g. the importance to wrap/seal food after opening, using packaging in the right way.

What should be kept in the fridge and which are temperature sensitive and should be stored in the coldest part of the fridge.

WRAP will work with the food and white goods sectors through the Courtauld Commitment10 and Home Improvement Sector Commitment11 to take forward these recommendations. Success would help both improve food safety in the home and could reduce food spoilage associated with poor storage that could lead to waste.

9 http://www.food.gov.uk/multimedia/pdfs/evidenceplan10.pdf 10 http://www.wrap.org.uk/retail/courtauld_commitment/index.html 11 http://www.wrap.org.uk/retail/home_improvement/index.html


Contents 1.0 Introduction ........................................................................................................................... 10

1.1 Background and context to the research ...............................................................................10 1.2 Overview of the refrigerated food supply chain......................................................................11 1.3 The domestic fridge market .................................................................................................11 1.4 Project team .......................................................................................................................12

2.0 Method ................................................................................................................................... 13 2.1 Store to home assessment ...................................................................................................13 2.2 Consumer research..............................................................................................................15

2.2.1 Consumer survey design and method.......................................................................15 2.2.2 Data analysis ..........................................................................................................15 2.2.3 In-home fridge experiment......................................................................................15

2.3 Experimental programme at Campden BRI............................................................................16 2.3.1 Controlled domestic fridge temperature study...........................................................16 2.3.2 Domestic fridge thermometer evaluation ..................................................................17

3.0 Store to home assessment ..................................................................................................... 18 3.1 Method summary ................................................................................................................18 3.2 Results................................................................................................................................19 3.3 Limitations of the study .......................................................................................................23

4.0 Consumer research ................................................................................................................ 24 4.1 Consumer survey.................................................................................................................24

4.1.1 Method summary....................................................................................................24 4.1.2 Discussion of the survey results ...............................................................................24 4.1.3 Limitations of the study...........................................................................................34 4.1.4 The changing customer – a comparison with previous research .................................34

4.2 In-home fridge experiment ..................................................................................................36 4.2.1 Method summary....................................................................................................36 4.2.2 Results ...................................................................................................................36 4.2.3 Limitations of the study...........................................................................................39 4.2.4 Comparison with other studies.................................................................................39

5.0 Experimental programme at Campden BRI ........................................................................... 41 5.1 Controlled domestic fridge temperature study .......................................................................41

5.1.1 Method summary....................................................................................................41 5.1.2 Results – temperature distribution ...........................................................................42 5.1.3 Results – fridge shelf construction............................................................................50 5.1.4 Results – humidity ..................................................................................................51 5.1.5 Limitations of the study...........................................................................................53

5.2 Domestic fridge thermometer evaluation...............................................................................54 6.0 Innovative domestic refrigerator design to improve food temperature control.................... 58

6.1 Current fridge design ...........................................................................................................58 6.2 Ideas to improve refrigerated food storage ...........................................................................58

6.2.1 Improvements in temperature control ......................................................................58 6.2.2 Improvements in accessibility of fridge items............................................................60 6.2.3 Innovations launched by manufactures to improve food storage life...........................61

6.3 ‘Blue sky’ ideas for improving the storage of refrigerated foods. .............................................62 6.3.1 Intelligent monitoring of shelf life.............................................................................62 6.3.2 Product identification ..............................................................................................62 6.3.3 Air curtains.............................................................................................................62

7.0 Recommendations.................................................................................................................. 63 Appendix 1 Quotas set for the Consumer Survey............................................................................... 65 Appendix 2 Analysis of Consumer Survey Population........................................................................ 67 Appendix 3 Detailed Results from the Consumer Survey .................................................................. 69 Appendix 4 Specifications of fridges used for consumer fridge temperature study .......................... 93


Glossary Avoidable waste: a classification used in the report relating to food and drink thrown away that was, at

some point prior to disposal, edible, e.g. milk, lettuce, fruit juice, meat (excluding bones, skin, etc.); c.f. possibly avoidable and unavoidable waste (source: WRAP).

Chill chain: Continuous steps of the food chain during which food needs to be maintained at the relevant specified chill temperature for reasons of safety and/or quality (source: CFA Definitions WG).

Chilled food: A prepared food that for reasons of safety and/or quality is designed to be stored at refrigeration temperatures (at or below 8°C, but not frozen) throughout its entire life (source: CFA Definitions WG).

Food safety: assurance that food will not cause harm to the consumer when it is prepared and/or eaten according to its intended use (source: Codex Recommended International Code of Practice - General Principles of Food Hygiene, CAC/RCP 1-1969, Rev. 3 (1997), Amd. (1999))

Possibly avoidable waste: a classification used in the report relating to food and drink that some people eat and others do not, e.g. bread crusts, or that can be eaten when a food is prepared in one way but not in another, e.g. potato skins; c.f. avoidable and unavoidable waste (source: WRAP).

Refrigerated food: The term used in this report to refer to all foods that are designed to be kept refrigerated for reasons related to safety or quality, plus any foods that benefit from being kept refrigerated (for example fresh fruit that retains its quality for longer if kept refrigerated).

Shelf life: Either the period corresponding to the period preceding the “use by” or the minimum durability date”. In practice it comprises the manufacturing shelf life plus the product shelf life.

Supply chain: all stages of production, processing and distribution further defined as any stage, including import, from and including the primary production of a food, up to and including its storage, transport, sale or supply to the final consumer (source: Regulation (EC) 852/2004 on the hygiene of foodstuffs).

Unavoidable waste: a classification used in the report relating to waste arising from food and drink preparation that is not, and has not been, edible under normal circumstances, e.g. meat bones, egg shells, pineapple skin, tea bags; c.f. avoidable and possibly avoidable waste (source: WRAP).

Acknowledgements Campden BRI gratefully acknowledges the technical guidance provided by WRAP and the Chilled Food Association.


1.0 Introduction 1.1 Background and context to the research Figures produced by WRAP on household food and drink waste show that UK householders are throwing away 8.3 million tonnes of food and drink per year in the UK, most of which (5.3 million tonnes) could have been consumed equating to £12 billion worth of food. We throw food out for two main reasons: we cook or prepare too much, costing us around £4.8 billion per year or we let food go off, either completely untouched or opened/started but not finished, costing £6.7 billion per year. WRAP research has shown there are many factors contributing to household food waste, such as: a lack of planning when food shopping - buying more than is needed; poor food storage in the home, including poor temperature control; a lack of confidence around cooking (especially making meals from the food available in the house, using

leftovers, and portion control); and confusion over food date labels (such as the difference between 'use by' and 'best before') and confidence to

cook or freeze foods that are close to their date. The amount of food we throw away is a major contributor to the production of greenhouse gases in the UK; equivalent to at least 20 million tonnes of carbon dioxide. Therefore, to help reduce the amount of food that is thrown away, WRAP and its partners are running the 'Love Food Hate Waste' (www.lovefoodhatewaste.com) consumer facing campaign to encourage behavioural change. WRAP are working with the UK grocery sector, food industry, Government and organisations such as the Food Standards Agency to develop practical solutions and improved communications to make it easier for consumers to get the most from the food they buy and waste less. WRAP's target is to reduce consumer food waste by 250,000 tonnes by March 2011. One of the largest contributions to food waste is from products that require or benefit from refrigerated storage, including fresh/raw meat and fish, ready meals, dairy products, fruit and vegetables and pre-prepared foods. A detailed breakdown of all avoidable food waste is given in Figure 1.

Figure 1 Weight of food and drink waste by food group, split by avoidability

million tonnes per year0.0 0.5 1.0 1.5 2.0

Fresh vegetables and salads

Drink

Fresh fruit

Bakery

Meals (home-made and pre-prepared)

Meat and fish

Dairy and eggs

Processed vegetables and salad

Condiments, sauces, herbs & spices

Staple foods

Cake and desserts

Oil and fat

Confectionery and snacks

Processed fruit

Other

Avoidable Possibly Avoidable Unavoidable

Source: Household Food and Drink Waste in the UK, WRAP, 2009


In order to prolong product shelf life through minimising microbial and chemical spoilage yet retaining food accessibility, fridges should be maintained at a temperature between 0°C and 5°C. If the air temperature in the fridge is lower than 0°C for prolonged periods, there is a risk that foods such as salad would be rendered unpalatable, for example, if they became partially frozen. If the converse is the case, and food product temperatures rise above 5°C, they are likely to spoil more quickly through the growth of microbes and the development of rancid flavours. In response to an open tender, published by WRAP in 2008, Campden BRI proposed a partnership approach to develop waste reduction strategies for the whole refrigerated food chain, from factory gate to the consumer comprising two key elements: 1. A survey and practical measurements of domestic refrigerator air temperatures and consumer behaviour

including: A controlled domestic fridge air temperature study; establishing links between air temperature data and

refrigerator age and design. A store to home assessment; experimental trials at Campden BRI to simulate consumer shopping habits. A domestic fridge thermometer evaluation. A consumer research survey; to understand refrigerated food practices in the home. An in-home fridge experiment; to ascertain the actual air temperatures at which domestic fridges are

operating. A desk top survey of novel refrigerator design concepts that might help improve refrigerator temperature

performance.

2. The identification of typical temperatures throughout each stage of the chill chain, e.g. on dispatch from the factory, during distribution (including handovers of product to the next link in the chill chain) and retail display.

This will identify the 'weak links' in the chill chain and provide a quantitative assessment of the likely food waste associated with poor chill chain temperature control.

The work will lead to a desk-top study of the availability and effectiveness of innovative packaging concepts such as temperature control/insulated packages (primary and secondary) on food temperature control in the chill chain. It will also make use of the results of another industry funded project at Campden BRI on the effectiveness of active and intelligent packaging for indication of temperature and quality of foods during storage, distribution and supply.

This project report details the results and conclusions from the first element of the project. 1.2 Overview of the refrigerated food supply chain The refrigerated food supply chain is often complex and involves several stages: food manufacturing and the transfer of chilled product into distribution; transportation of product to an intermediate or regional distribution centre for storage; distribution of refrigerated food to the retail store; retail display on the supermarket/store shelf; and consumer transport of the refrigerated food home to the domestic fridge.

Of course, if temperature control in any part of this refrigerated food chain is not maintained, then the integrity of the refrigerated food may be compromised. This might manifest as a food safety problem or result in food spoiling before the food date (i.e. becoming unsightly or unpalatable). It is likely that if the consumer is unsure, particularly for certain product categories such as fresh meat, fresh fish and dairy products, then the food will be disposed of. Conversely, if improvements can be made in the chilled supply chain and operation of domestic refrigerators, then there may be potential to increase the shelf-life of foods that depend on refrigeration. 1.3 The domestic fridge market According to the Market Transformation Programme, 2009, UK domestic fridge appliance sales in 2009 totalled 2,047,278, a fall of 2.3% since 2005. Sixty-one percent of these were combined fridge-freezer units with the remaining 39% as standalone fridges. These sales brought the estimated number of domestic fridge appliances in UK homes at the end of 2009 to 27,859,755, with 65% of those as combined fridge-freezer units. Data12 would suggest that the majority of UK fridges have glass shelves (approximately 90%).

12 Beijing Inforce Consulting Ltd, July 2009


Based on data from the consumer survey part of the project, the ages of fridges were modelled using a Weibull distribution, a statistical distribution that can be used to look at survival rates. This showed that the mean age of a fridge was 4.3 years and the median 3.78 years (Figure 2). The distribution suggests that there is a long tail of fridge age, with a number of fridges that are older than 10 years.

Figure 2 Distribution of fridge age

However, the distribution indicates that 75% of domestic fridges will be replaced after 5.8 years. Data from Mintel 200913 indicates that most white goods are replaced on a seven year cycle. 1.4 Project team The project team for this work included the Departments of Consumer & Sensory Science and Food Manufacturing Technologies at Campden BRI working with WRAP. Campden BRI is an independent membership-based organisation carrying out research and development for the food and drinks industry worldwide, with a well-established reputation for providing industry with the research, technical and advisory services to ensure product safety and quality, process efficiency and product and process innovation.

13 Mintel 2009; White Goods, Retail Intelligence, June 2009. Mintel International Group Ltd


2.0 Method This section, describing the methodology used in this evaluation, is split into three sections, experimental work to mimic the store to home journey, the consumer research programme conducted at household locations throughout Great Britain, and the controlled laboratory measurements on fridges and fridge thermometers conducted at Campden BRI. Fridge air temperatures, rather than product temperatures, were recorded throughout this research. This reflects how consumers would measure fridge temperatures using most domestic thermometers. 2.1 Store to home assessment The 'store to home' assessment was intended to quantify the likely changes in temperature within a range of refrigerated foods, after they had been purchased by the consumer from the retailer and during the transit home to the consumers' own fridge. In order to remove any uncontrolled, extraneous factors from influencing the results of this test, the 'store to home’ assessment was conducted under controlled temperature conditions at Campden BRI in August 2009. These conditions were chosen to replicate the likely temperatures to which refrigerated foods could be subjected once they had been removed from the supermarket chilled display cabinet. A typical shopping load was chosen for this test and the selected products were subjected to a series of simulated store to home journeys, with multi-point temperature measuring devices monitoring food, packaging and environment temperature in the shopping bags. Following discussions with WRAP, the refrigerated foods selected for the test encompassed a range of food types, size, packaging formats and physical properties (e.g. product density, thermal conductivity and heat capacity). The following six products were chosen: Iceberg lettuce. This represents a low density product, with a large exposed surface area. The product is

wrapped in a cellophane package. It is often placed in the salad/vegetable compartment of fridge, which had been shown in previous work to be one of the warmer areas within the consumer fridge.

Margarine (500g tub). This provided a homogeneous food type, with relatively high density and low heat capacity. It also represented a regular block shape with close fitting plastic package around the food.

Milk (2 pint). This represented a liquid food product with good thermal conduction/convection heat transfer. The plastic package provides a large surface area to the product and it is often placed in the door compartment of the consumer fridge (also shown in previous work to be one of the warmer areas of the fridge).

A chilled lasagne ready meal (350g). This provided a high density product, with regular shape. It also represents a multilayered type of food and the plastic package with film lid is further contained within a cardboard outer.

Sliced ham (200g). This is a flat packed product, giving a large surface area to volume ratio. The plastic package is close fitting to the product and the low water/high fat content of the ham gives a relatively low heat capacity.

Fresh cream cake. This is a relatively low density food product, with multiple components (sponge, cream, jam layers). The product is contained in a loose fitting plastic carton.

Each of the food products was packed in three types of carrier bag during the store to home trial. A standard polyethylene carrier bag (typically free of charge at the supermarket checkout), a woven cloth carrier bag (typically 30-40 pence each at the supermarket checkout) and a thermally insulated carrier bag (typically £1-£2 each at the supermarket checkout) were used. Figure 3 shows the three carrier bags used in the store to home assessment test.

Figure 3 Carrier bags used: polyethylene (left), woven (centre) and insulated (right).


To develop a representative testing protocol, reference was made to the Campden BRI Guideline Document No.46 'Evaluation of produce shelf-life for refrigerated foods' (2004). This document had been developed by Campden BRI, in conjunction with an industry working party, specifically to develop representative test methods to evaluate the shelf life of refrigerated foods. The document concluded the following points which are relevant to this project: The temperature of refrigerated food products rises rapidly during the time that it is transported from the

shop to the consumer's home. The product temperature can rise relatively quickly, especially during the warmer months, even if ice-packs and cold-boxes are used.

In addition to the time taken to transport shopping to the home, there is also the time in-store where refrigerated foods may sit in a shopping trolley whilst the remainder of the shopping is done.

A survey conducted by the working party showed that 95% of shoppers took less than 50 minutes to complete their shopping, whether it was a main shopping trip or a top-up shop. The average time spent driving back from the store was 15 minutes with a maximum of 30 minutes.

Conditions representative of a consumer's shopping habits would be one hour spent in the store and a further 1 hour spent loading the shopping into the car, driving home and unloading shopping.

For the purpose of this test, three different temperature regimes were used to reflect the different conditions likely to be experienced by refrigerated foods as they are purchased and returned to the home. The temperature of 4°C was chosen to comply with chilled food industry guidance to store chilled foods below 5°C in a retail food business14. 1. Storage at 4°C followed by two hours at 20°C before return to the fridge at 4°C. These conditions could

reflect retail display, time spent in store, and time spent in a car/transport home during warmer months. 2. Storage at 4°C followed by one hour at 20°C and one hour at 10°C before return to the fridge at 4°C. These

conditions would reflect retail display, time spent in store, and time spent in a car/transport home during colder months (best case).

3. Storage at 4°C followed by one hour at 20°C and one hour at 30°C before return to the fridge at 4°C. These conditions would reflect retail display, time spend in store and time spent in car/transport home during warmer months (worst case).

The foods were allowed to equilibrate to the required chilled start temperature (nominally 3-4°C) in a chill room at Campden BRI prior to each test. This simulated temperatures within the foods at the retail display stage. Following the temperature change phase of the test, the products were returned to the controlled temperature room at 4°C and removed from the carrier bag, to simulate being stored in a domestic refrigerator. Two examples of each of the six food products in each of the three carrier bag types were used and provided replicate measurements for each product. Thin wire thermocouples, connected to a temperature datalogger, were used to measure and record product temperature during the three simulated store to home tests. Temperature measurements were taken at 10 second intervals to a resolution of better than 0.1°C. Probes were placed at the centre and at the edge of each product. For the milk, a thermocouple probe gland was used to locate the temperature sensing tip at the centre. Thermocouple probes were also used to measure the ambient temperature in the shopping bag and the external environment. The above series of tests were repeated three times to assess any variability in the results obtained.

14 http://www.chilledfood.org/MEDIA/POSITION+STATEMENTS/temperature.htm


2.2 Consumer research 2.2.1 Consumer survey design and method The consumer survey was designed to examine: consumer shopping patterns and practices; food storage practices and expectations; refrigerator practices and implications for food waste; and observations of refrigerator characteristics and measurement of refrigerator temperatures at a single

timepoint (among all survey respondents), with temperature measurements over time among a subset of survey respondents (refer to relevant report/section for further detail in this area).

The survey was, in part, based on the 1991 survey undertaken for MAFF15. A comparison of the results is included in the later discussion. The survey consisted of a quota sample of 329 households drawn from the GB population. Quotas were set on socio economic status, lifestage and region (TV area) with these quotas being regarded by the research team as potentially important influences on attitudes and behaviours in relation to this research. The quotas set reflected the GB population profile as published by the Mintel International Group Ltd (a commercial market research company). Detailed information is given in Appendix 1 and 2. If participants satisfied the pre-screening requirements (whether they were wholly or mainly responsible for carrying out and unpacking the main grocery shop and whether they had a working domestic fridge), an interview was scheduled as close as possible to when the participants’ main shop had been completed. All participants were interviewed in their homes between the 8th – 23rd July 2009. Each interview consisted of an interviewer-led questionnaire capturing participants’ self-reported attitudes in relation to food purchases, transportation, storage and refrigerator practices followed by observations made by the interviewer recording refrigerator temperature, location and other characteristics. Photographic images of the exterior and interior of the refrigerator were also captured. 2.2.2 Data analysis The data were analysed by a number of methods which are described below. For a number of questions, selected categorical variables were cross-tabulated, for example, lifestage and their associations were analyzed using Pearson’s Chi-Square Test. A chi-square test tests for association between variables of the frequency counts. The null hypothesis states that no association exists between variables. A one sample t-test was performed on attitude statements to establish if there was a significant difference from the null hypothesis score of three (neither agree nor disagree with the statement) where a score of one represents strongly disagree and a score of five represents strongly agree. For a number of questions, the Pearson correlation coefficient r and associated P value were calculated to establish the significance level of the correlation coefficient. Full results are given in Appendix 3. The definition of the lifestage groups and the proportion each represents of the survey population is shown below (the quota was intended to reflect the population as a whole): Pre-family/no family: aged under 45 who are not parents (16%) Family: any age with at least one child aged under 16 still at home (26%) Third Age: aged 45-64 with no children aged under 16 (28%) Retired: aged over 65 with no children aged under 16 (30%) 2.2.3 In-home fridge experiment Following the survey of 329 households on their use of refrigerated foods and data on the fridges in the home, a selection of 50 households were chosen to provide more detailed air temperature information from within the domestic fridge. The 50 households were chosen to represent a range of demographics, fridge types, fridge age, fridge make/model and geographical area. These details are given in Appendix 4. The experiment took place in August and September 2009.

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


Air temperatures were measured in each of the 50 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 ambient temperature in the vicinity of the fridge was also recorded. Participants were asked to continue using their fridges in the usual manner, and were not asked to keep a detailed diary of fridge use (for fear of this prompting them to change from their normal use and potentially affect the validity of the results). In order to maintain consistency in the placement of the temperature dataloggers, they were put in place by an experienced researcher and retrieved at the end of the measurement period and returned to Campden BRI for data analysis. 2.3 Experimental programme at Campden BRI Two series of controlled laboratory tests were conducted in this part of the project; namely a controlled domestic fridge air temperature study, and an evaluation of domestic fridge thermometers. 2.3.1 Controlled domestic fridge temperature study In a series of experimental tests in July 2009, six fridges at Campden BRI were used, allowing greater control over conditions (e.g. temperature and humidity measurements, fridge loading, door opening and environmental conditions) than could be practiced in consumers' homes. The six fridges chosen for this test encompassed, as far as practicable, a range of makes, models and designs. This included 'under-worktop' larder fridges, fridge compartments of upright fridge-freezers, large 'American-style' fridges and fridges with integrated freezer compartments. As the objectives of these tests were to ascertain the typical air temperature/humidity distributions within domestic fridges, the fridges were filled with a 'model food load' for the duration of these tests (Figure 4). These were 'freezer gel packs', which would not themselves contribute to humidity variations in the fridge (as real food loads would). The model food was loaded into each fridge to cover 50% of the useable fridge shelf area, in a reproducible pattern to ensure that airflow distributions were the same for each fridge tested.

Figure 4 Fridge with representative load of gel packs

Prior to starting each test, the model food loads were allowed to equilibrate to chilled temperatures (ca. 4°C). The purpose of these tests was not to determine food temperatures, but the change (rise and recovery) in fridge air temperature and humidity distributions as the fridge door was opened and closed during a 'typical' day. The experiments were not designed to align with ISO standards, which set out test methods for household refrigerating appliances, but to simulate a real life environment. Hence, the controlled domestic fridge study tests air temperature rather than product temperature as this is what the consumer will measure using most domestic thermometers.


Temperature data loggers were used for this study and placed in key areas throughout the fridge to record fridge air temperatures. Temperature probes were placed in the top shelf (centre and edge), middle shelf (centre and edge), bottom shelf (centre and edge), 'salad crisper compartment', and fridge door (top and bottom). A minimum of nine probes were used in each fridge. Fridge humidity was measured using loggers similar to those used for temperature measurement. Temperature and humidity measurements were recorded at 30 second intervals for a period of 24 hours for each fridge, to a minimum resolution of 0.1°C. Ambient temperature was also recorded during the tests. To reflect actual use, the fridge door was opened every hour (minimum six times) and remained open for two minutes each time during the six hours of fridge operation during a typical working day. This fridge opening time was chosen to represent typical use of the fridge. It was realised that on some occasions a consumer would open the fridge door for a much shorter time; however, short openings were likely to produce very erratic data that would be difficult to compare and other variables could become more significant e.g. speed of door opening/closing. The information gained from this part of the study included: detailed mapping of spatial variation in fridge air temperatures; detailed mapping of spatial variation in fridge humidity; information on maximum, minimum and average temperature (only average temperatures are reported in this

study); indication of potential cold-spots or hot-spots in domestic fridges; and indication of hysteresis (time taken for fridges to warm-up on door opening and subsequently recover a

chilled air temperature). It is important to note that depending on the temperature of food going into the fridge, its density and its packaging the fridge air temperature will not directly correlate to product temperature. Nor will product temperature fluctuate at the same speed or range as air temperature.

2.3.2 Domestic fridge thermometer evaluation A separate study undertaken for WRAP by Campden BRI evaluated a wide range of domestic fridge thermometers available to the UK consumer. The results of this work are presented in a separate report16 but would be of interest to those reading this report. The assessment of the fridge thermometers was done in three stages: 1. A survey of the range and types of fridge thermometers available to UK consumers was conducted and

examples were purchased for the evaluation phase of the study. The assessment encompassed fridge thermometers from across the range available to consumers, including replicate samples of one device to assess the repeatability of the device.

2. An assessment programme was undertaken to measure fridge thermometer performance, including: accuracy of temperature measurement; resolution, readability and clarity of each fridge thermometer; response times of each thermometer to a change in fridge temperature; and consistency of fridge thermometer performance. 3. An assessment was made of the guidance given to the consumer on the packaging, on how to use the fridge

thermometer. Key factors included assessing the presence and accuracy of: advice on reading the temperature display, e.g. how to read the thermometer accurately and consistently; advice on interpreting the reading given on the fridge thermometer, e.g. what does the temperature mean? advice on where to place the thermometer in the fridge; advice on what temperature the fridge should be set to; advice on what the consumer should do if the thermometer indicates that the fridge temperature is outside

the recommended temperature range; and the clarity of the advice given to the consumer.

16 A performance assessment of domestic fridge thermometers, WRAP, 2009.


3.0 Store to home assessment The 'store to home' assessment was conducted to quantify the changes in temperature within a range of refrigerated foods, after they had been purchased by the consumer from the retailer and during the transit home to the consumer’s own fridge. This test was conducted under controlled temperature conditions at Campden BRI. These conditions were chosen to replicate the likely temperatures to which refrigerated foods could be subjected once they had been removed from the supermarket chilled display cabinet, which are recommended to operate below 5°C17. 3.1 Method summary For this test, six different food products (a two pint milk container, a 350g lasagne ready meal, a 500g container of margarine, an iceberg lettuce, a 200g pack of sliced ham and a cream cake) were monitored for temperature changes in three simulated chill chain situations (indicated below), in each of three different carrier bag types (standard, woven and insulated, shown in Figure 3 above).

1. Storage at 4°C followed by two hours at 20°C before return to the fridge at 4°C. 2. Storage at 4°C followed by one hour at 20°C and one hour at 10°C before return to the fridge at 4°C. 3. Storage at 4°C followed by one hour at 20°C and one hour at 30°C before return to the fridge at 4°C

The rationale for these temperature ranges is discussed in Section 2.1.2 above. Temperature data was collected at the centre and surface of the foods during each test. The selected products were subjected to a series of simulated store-to-home journeys, with multi-point temperature measuring devices monitoring food, packaging and environment temperature in the shopping bags. Once the two hour monitoring period had elapsed, the food products were returned to a chiller at 4°C. As the start temperatures and first hour of the trial is the same for each test (starting from the same chiller followed by one hour at 20°C) it is only in the second hour that there is a temperature variation. Therefore, the tables below only show the end temperatures. Figure 5 shows the loading arrangement for the products in the carrier bags. The products were arranged as might be expected from a typical consumer, with the ready meals, margarine and ham near the bottom of the bag, the milk containers standing upright at the sides of the bag and the cream cakes sitting on top. This arrangement was consistent for each of the bags and for each of the three simulated chill chain situations.

Figure 5 Loading arrangement for each carrier bag.

17 http://www.chilledfood.org/MEDIA/POSITION+STATEMENTS/temperature.htm


3.2 Results Tables 1-3 show, for each of the three different carrier bags, when taken out of the fridge and subjected to the three test temperature conditions: the average temperature after two hours; the average temperature after five hours (which is when data collection stopped); and the average peak temperature (at any point during the five hour experiment).

These data points have been selected to show the temperature change after the simulated journey of two hours. They also reveal that the products may be above the desirable storage temperature range (0-5ºC) for a long period of time, over and above the journey time. Some products hadn't reached the desired temperature even after a period of three hours of being in the fridge. In fact, some of the products took up to 15 hours to return to below 5°C with the chiller operating at 4.3°C. It is likely that this ‘recovery’ time would be longer in a domestic refrigerator due to the lower airflow and space limitations that mean that products are often stacked up or pushed close together. This finding underlines the importance of not allowing products to warm up significantly during shopping and transport. The temperatures shown are absolute, rather than a temperature rise. However, it should be noted that there was some variation in starting temperatures from run to run. The speed at which the temperature changes for each product will depend on its properties, the temperature around it and how fast heat can be supplied; this will be influenced by the properties of the bag and the product’s position, packaging or how close it is to the side of the bag. Generally, as low density products - such as cream cakes - have a low heat capacity they are likely to be more affected by external temperature changes. Denser products have a higher heat capacity and therefore change temperature more slowly. Therefore, the lasagne was the slowest to heat after removal from the fridge and the lettuce and sliced ham were the quickest to rise in temperature. The results of this test indicate the following: The insulated bag kept all the foods at lower temperatures than the other two bags in all three test conditions

and especially at the warmest temperatures (Test 3)18. The edge of the lasagne, cream cake and margarine were most likely to rise in temperature in all tests,

including the insulated bag. The woven bag also performed well; the results for this bag type are largely comparable to the insulated bag

for Tests 1 and 2. At lower temperatures (Test 2) all bags performed well; maintaining temperatures of below 5°C for all

products. The results for the standard bag seem to indicate that although it doesn’t have very good insulating properties

(with product temperatures being significantly higher in Test 2 than Test 1) the non-insulating effect doesn’t seem to be amplified at higher temperatures; with the results for Test 3 being largely comparable to those for Test 2.

The conclusions that can be derived from this work are that using insulated bags for refrigerated food, particularly during warmer months, will help reduce the degree to which product temperatures may increase. The number of consumers now using the ‘bags for life’ would suggest that this might not be a particularly difficult behaviour to adopt. More importantly, however, consumers should be alerted to the magnitude of the food temperature rises that can occur during shopping and transport. Given the particularly good results for all bag types of Test 2, it may be beneficial to remind all consumers, when in-store, to pack refrigerated and frozen items together where possible and transport chilled and frozen foods as quickly as possible to minimise the risk of food spoilage.

18 There was some variation within the results and this is likely to be due to small variations in product placing that were an unavoidable part of the tests.


Table 1 Test 1 - Storage at 4°C followed by two hours at 20°C. Bag type

Standard bag Woven bag Insulated bag Temperature (ºC) Food product Measurement

Centre (1)

Centre (2)

EdgeCentre (1)

Centre (2)

EdgeCentre (1)

Centre (2)

Edge

Temperature at 2 hrs 12.3 11.9 7.7 8.2 7.3 7.8 Temperature at 5* hrs 5.7 5.7 5.4 5.7 5.9 6.0 Milk Peak temperature 11.8 11.6 10.3 8.8 8.1 8.3 Temperature at 2 hrs 11.1 7.6 9.8 9.8 8.7 9.0 5.9 6.2 7.7Temperature at 5* hrs 5.5 5.5 5.1 5.3 5.2 5.0 5.7 6.1 5.7Lasagne Peak temperature 10.1 7.2 10.1 10.0 7.2 7.3 7.6 7.3 7.3Temperature at 2 hrs 11.0 12.7 16.4 6.8 10.0 13.2 7.9 9.2 11.7Temperature at 5* hrs 5.8 6.4 5.7 5.8 6.6 5.6 6.3 6.8 5.8Cream cake Peak temperature 9.2 11.0 14.8 7.1 10.5 12.8 11.2 12.3 13.8Temperature at 2 hrs 10.7 12.2 13.5 9.3 7.7 8.2 7.9 7.8 10.0Temperature at 5* hrs 6.0 5.8 5.4 5.3 5.5 5.4 6.1 6.5 5.3Margarine Peak temperature 11.0 12.2 12.3 10.2 8.3 8.8 7.8 7.8 8.4Temperature at 2 hrs 9.8 9.0 8.9 7.8 11.9 7.6 Temperature at 5* hrs 7.5 8.8 6.6 6.8 8.3 8.7 Lettuce Peak temperature 12.0 10.5 7.9 8.9 18.3 8.2 Temperature at 2 hrs 13.1 15.7 6.9 7.1 7.5 9.8 Temperature at 5* hrs 5.8 5.4 5.7 5.5 6.3 5.7 Sliced ham Peak temperature 14.2 16.2 7.2 7.7 8.4 9.8 Temperature at 2 hrs 13.1 13.1 19.9 Ambient'

(temperature probe in the bag) Temperature at 5* hrs 5.4 5.5 4.9

*Note - the standard bag experiment ended after 4 hours, rather than 5


Table 2 Test 2 - Storage at 4°C followed by one hour at 20°C and one hour at 10°C. Bag type


Centre (1)

Centre (2)

EdgeCentre (1)

Centre (2)

EdgeCentre (1)

Centre (2)

Edge

Temperature at 2 hrs 7.1 7.2 6.8 6.7 6.6 6.3 Temperature at 5* hrs 5.2 5.2 4.4 4.6 4.6 4.6 Milk Peak temperature 7.6 7.7 7.6 7.6 6.9 7.1 Temperature at 2 hrs 7.4 5.6 6.2 6.8 5.7 6.2 5.4 6.5 7.4Temperature at 5* hrs 5.2 5.4 4.9 4.5 5.0 4.5 5.0 4.4 3.6Lasagne Peak temperature 7.7 6.1 6.4 7.7 5.9 6.3 6.1 6.7 7.1Temperature at 2 hrs 9.5 7.6 9.6 8.1 6.6 6.6 5.8 7.1 8.2Temperature at 5* hrs 6.1 5.4 5.3 4.8 5.1 4.2 4.8 5.1 3.6Cream cake Peak temperature 9.7 8.3 11.0 8.7 7.4 11.5 6.6 7.7 NA Temperature at 2 hrs 7.6 6.7 7.9 6.3 6.5 7.2 6.1 6.7 7.6Temperature at 5* hrs 5.6 5.3 4.9 4.6 4.5 4.5 4.4 4.8 3.8Margarine Peak temperature 7.8 7.1 8.1 7.6 7.1 7.7 7.3 7.4 9.1Temperature at 2 hrs 8.9 7.4 8.5 7.6 8.1 7.5 Temperature at 5* hrs 7.2 7.6 5.4 5.6 6.5 6.5 Lettuce Peak temperature 9.6 8.3 8.1 7.6 9.2 8.4 Temperature at 2 hrs 8.4 7.6 6.2 6.6 6.2 5.6 Temperature at 5* hrs 5.6 5.9 4.7 4.7 4.7 4.7 Sliced ham Peak temperature 8.7 8.1 6.3 6.7 6.6 6.2 Temperature at 2 hrs 10.7 7.7 9.4 Ambient'




Table 3 Test 3 - Storage at 4°C followed by one hour at 20°C and one hour at 30°C. Bag type


Centre (1)

Centre (2)

EdgeCentre (1)

Centre (2)

EdgeCentre (1)

Centre (2)

Edge

Temperature at 2 hrs 10.7 9.8 10.9 11.9 9.1 9.8 Temperature at 5* hrs 10.1 9.5 5.1 5.4 5.2 5.4 Milk Peak temperature 11.6 11.1 10.3 11.8 8.7 9.8 Temperature at 2 hrs 7.3 7.3 11.5 8.0 10.3 12.7 11.1 6.4 16.0Temperature at 5* hrs 8.3 8.1 7.8 6.2 5.7 4.9 5.7 6.3 5.6Lasagne Peak temperature 7.9 10.0 15.4 8.2 8.9 11.5 12.6 7.2 7.4Temperature at 2 hrs 11.4 8.3 13.4 13.9 10.6 13.9 8.5 9.0 13.3Temperature at 5* hrs 10.2 9.2 8.6 5.9 6.7 5.3 5.5 5.8 5.2Cream cake Peak temperature 12.3 9.2 13.0 14.3 11.2 14.0 8.1 8.8 13.1Temperature at 2 hrs 9.3 7.6 11.2 8.5 10.2 10.4 7.3 9.3 12.8Temperature at 5* hrs 9.1 9.4 9.0 6.1 5.4 5.4 5.6 6.1 5.2Margarine Peak temperature 10.2 10.5 13.5 7.9 9.5 9.5 7.2 9.7 9.8Temperature at 2 hrs 19.1 10.6 11.8 9.5 10.0 10.1 Temperature at 5* hrs 8.7 11.8 6.5 7.2 8.2 7.2 Lettuce Peak temperature 14.1 14.2 10.3 11.0 10.2 10.2 Temperature at 2 hrs 18.6 10.1 14.7 8.5 6.9 6.3 Temperature at 5* hrs 8.5 10.5 5.1 5.5 5.7 6.1 Sliced ham Peak temperature 14.8 11.8 14.3 8.3 7.7 6.8 Temperature at 2 hrs 20.8 18.7 22.5 Ambient'




3.3 Limitations of the study This study of the temperature rise as foods are transported simulates the effects of purchase and transportation of a representative shopping bag of refrigerated foods from the store to home. Consumer behaviour could vary markedly from this study, for example: Rearranging the products in the trolley or bag (e.g. during the checkout operation) could cause some food

items to warm more quickly. The placement of refrigerated food items next to warmer items (e.g. cooked chickens, bread) may contribute

to larger temperature rises than recorded in this study. Conversely, placing a chilled product adjacent to a frozen item may help maintain low chilled temperatures.


4.0 Consumer research 4.1 Consumer survey A key part of this project was an extensive survey of refrigerated food practices in the home, the results of which provide an insight into consumer food purchasing, food storage, fridge ownership and management of food items. 4.1.1 Method summary The survey consisted of a quota sample of 329 households drawn from the GB population. For a number of questions posed by an experienced interviewer to the consumer, the data was analysed by a number of methods as described in Section 2.2.2 of this report. The responses to the questions are given below. Participants were asked about their practices around some specific food products. These were: milk; cheese; chilled prepared meals; fresh meat; fresh fish; cooked meats; bacon; apples; carrots; and eggs. The quotas set during the study, analysis of survey population and detailed results for the consumer study are given in the Appendix. 4.1.2 Discussion of the survey results Food purchasing In terms of food purchasing, overall, 88% of participants stated that they generally carried out a regular major food shop and most of these (70%) carried out this shop once a week. A further 15% usually conducted a main food shop a couple of times a month. The most frequently cited shopping days were Saturday (18%), Friday (17%) and Thursday (11%) however, 32% of respondents stated that their main shopping day varied. For 90% of respondents the car was the mode of transport usually used for the main shopping trip. Nearly 15% of all respondents stated that they shopped daily to carry out top up shopping with a further 56% visiting every 2-3 days. Among working respondents undertaking top up shopping, 67% stated that this day was usually variable. Among buyers of each of the ten selected food items included in the research, a major supermarket was the ‘usual’ outlet used for all the food items. However, in respect of those buying fresh/raw meat (96% of the survey population), 15% cited that they usually used a specialist shop. Of those buying milk (all respondents bar one), around 8% usually used a milkman and a further 8% a small grocer/local shop. Among those buying eggs (98% of respondents), just over 8% cited that they used a farm shop. Fresh/raw fish was the item that recorded the most non-purchasers (22%) although again, among buyers, the main supermarket was the primary outlet used, with just over 7% of buyers using a specialist shop. A substantial number of respondents stated that they did not check the contents of the refrigerator before a major shop (either thoroughly (32%) or briefly (39%)) with the implication that this may lead to unnecessary food purchases. The store to home journey Overall, 45% of respondents stated that the usual time between completing the main grocery shop and unpacking was up to 30 minutes, with a further 23% stating this was between 30 minutes to one hour. Around a quarter of the survey population stated that the duration between shopping and unpacking was between one to two hours, with the remaining respondents taking two hours or more. The usual duration between shopping and unpacking for top-up shopping, was shorter than the main shop with 63% stating that their journey time was up to 30 minutes (the equivalent result among for the main shop was 45%). A further 27% of respondents stated that the usual journey time was between 30 minutes to one hour.


While 69% used the car for top up shopping, a much higher proportion (25%) made the journey by foot compared to the equivalent result in respect of the main shop (4%). Only 13% of all respondents used a cool bag/box to bring refrigerated foods home. This varied markedly between lifestage groups with only 6% of the pre-family group using one, 9% of the family group, 15% of the third age group and 22% of the retired group. The use of a cool bag/box had a limited corresponding relationship with the time taken between completing and unpacking the main shop as 25% of the pre-family group took more than one hour, among the family group this was 33%, 37% of the third age group but only 31% of the retired group. Food storage at home In terms of food storage in the home (Figure 6), almost all milk, cheese and cooked meat buyers, 90% of chilled ready meal buyers and 88% of bacon buyers stored these in the refrigerator (the remainder stored them in the freezer, which was also true for three out of ten fresh meat and fish buyers). Eggs, if not kept in the fridge, were stored on a kitchen work top by 19% of buyers. Apples, if not in the fridge, were stored by 38% of buyers on a kitchen work top or vegetable basket in the light (27%). Carrots if not stored in the fridge were stored in vegetable baskets, some in the light (13%), or in the dark (11%). WRAP research19 has shown that storing apples and carrots in the fridge can maintain their quality and extend their in-home life, making it easier for consumers to eat the whole pack and avoid wasting any.

Figure 6 Those storing selected food items in the fridge (Base: buyers).

99.1 99.7

89.7

72.8 71.1

98.7

87.9

22.1

64.270.9

0

20

40

60

80

100

Mi lk CheeseChi l led Ready

Meals

Fresh Meat

Fresh Fish

Cooked meats

Bacon ApplesCarrots Eggs

Pe

rce

nta

ge

sto

rin

g in

fri

dg

e

Food types

Just over eight out of ten apple buyers (85%) stored this item loose (i.e. removed from packaging); this was true for 56% of carrot buyers. How items were stored once opened and partly consumed varied across the nine food items. Not surprisingly milk is usually stored by almost all respondents (96%) in its original packaging in the fridge. In terms of apples, the majority (63%) stored this item out of the fridge with 19% in the fridge, while 56% stored carrots in the fridge. The storage of opened cheese was more variable with just over a third of buyers (34%) storing the product in its original packaging in the fridge, and a further 40% in the fridge but in an alternative wrapping. Nearly a fifth (19%) stated that they decanted this item into an airtight container. The storage of cooked meats was similar to that of cheese in that 42% of buyers stored the product in its original packaging in the fridge, and a further 37% in the fridge but in an alternative wrapping. Just over 11% decanted opened/cooked meat into an airtight container. In terms of chilled ready meals, most respondents either kept the product in the fridge in its original packaging (41%) or disposed of the product if not completely finished (42%). Fresh meat was fairly equally stored in the fridge (30%) either in original packaging or in an alternative wrapping although nearly a fifth (19%) would 19 Helping consumers reduce fruit and vegetable waste, WRAP, April 2008


dispose of the item if not completely finished. In respect of fresh fish just over two fifths (42%) would dispose of the item if not finished. Around six in ten (60%) of all respondents stated that they always followed storage advice on packaged foods (e.g. keep refrigerated) with a further 34% following them some of the time. Nearly six in ten of all respondents (58%) found current guidance on when to eat food (e.g. best before dates) extremely or very helpful. Use of the fridge to defrost food Around 35% of the survey population stated that they defrosted food in the fridge. Just over a further quarter of the survey population (26%) stated that they sometimes defrosted food in the fridge. No statistical differences were recorded between lifestages. Shelf life expectations Among buyers who provided a response, cheese, followed by eggs, were cited as having the longest expected shelf-life from the time of purchase (Figure 7). Shelf-life expectations for chilled ready meals were 3.6 days on average, 2.8 days for fresh meat and 1.8 days for fresh fish. The storage expectations for apples at 7.5 days and carrots at 7.2 days seemed relatively short (however, it’s not clear whether this is because they would likely have been eaten in this time, or whether the respondents felt they would have gone off). Not surprisingly across all the food items, expectations of how long the food items would last fell once opened and partly eaten compared to when unopened. The most significant difference was recorded for chilled ready meals where storage expectations fell by more than half and may explain the relatively high proportion of buyers who disposed of the product if not completely finished (42%). A decline in storage expectations was also noticeable in respect of fresh meat, bacon and fresh fish.

Figure 7 Average (in days) food storage expectations from time of purchase (unopened and opened) Base = buyers of each item.

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Fridge ownership and condition In terms of fridge ownership, around 87% of respondents had one fridge, 12% had two and just over 1% had three fridges. Not surprisingly the proportion with two or more fridges (4%) was markedly lower among the pre-family group compared to the other lifestages. Thirty-one per cent of all respondents stated that their main fridge was more than 5 years old (Figure 8), meaning that 70% had replaced their fridge in the last 5 years.


Figure 8 Age of main refrigerator (Base = 329).

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Across the survey population the majority of fridges were fridge/freezer combinations (58%) - with most having a fridge at the top and the freezer below. These fridge types were particularly evident among the pre-family and family lifestages. Among the retired lifestage group, the proportion of standalone fridges was significantly higher compared to the family lifestage group. Just over 82% of the interviewers rated the fridge door seals as 'Excellent' or 'Good' (NB this was a subjective assessment on the part of the interviewers and has not been validated). Poorly fitting or damaged door seals allow outside air into the fridge and can affect the unit’s efficiency and ability to maintain the correct temperature. Interviewers were instructed to take digital photographs of the exterior and interior of respondents' fridges. A full set of images for each household was captured. A selected number are shown in Figures 9-12 grouped by lifestage. Across the survey population, in 20% of the households, the fridges were rated as completely full, with a further 33% rated as three quarters full.


Figure 9 Pre-family lifestage group - examples from image database.


Figure 10 Family lifestage group - examples from image database.


Figure 11 Third age lifestage group - examples from image database.


Figure 12 Retired lifestage group - examples from image database.


Fridge temperatures It is encouraging that, unprompted, 79% of respondents correctly stated that the fridge should be run at between 0oC to 5oC, although just over 10% of respondents did not provide a response, 4% said either -2oC or -1oC and 5% said 6oC20. When asked how they would know if their fridge is running at the right temperature, nearly 6 in 10 respondents stated they relied on personal judgement i.e. 'if the food felt cold'. Nineteen per cent of respondents stated that they would not know if the fridge is at the right temperature - this was particularly true among the older lifestages (24% among the retired group compared to 11% among the pre-family group). Just over half of households adjusted their fridge dial, around a further third said that they left their setting unchanged. Responses to several of the attitude statements indicated that there are a number of fridge practices that have implications for food waste. Notably a significant proportion of the survey population (16%) agreed with the comment that fridge temperatures do not make much difference to how long food lasts. Interviewers were asked to note whether the fridge had an integral temperature display or a fridge thermometer present. Fourteen per cent of the survey population had an integral temperature display and from this group, for 38 respondents (12% of the survey population21), the temperature reading was captured. Those fridges with an integral display recorded an average temperature of 3.4oC. Just over 9% had a fridge thermometer and these thermometers recorded an average temperature of 4.5oC22. Almost all of those with an integral temperature display or a thermometer present in their fridge correctly stated that the temperature of a fridge should be between 0oC to 5oC. Only two gave no response to this question. The survey also aimed to ascertain an approximate air temperature of the participant’s fridge. Therefore, before starting the interview, interviewers placed a thermometer flat on the middle shelf of the respondent's main fridge towards the back of the shelf. The fridge door then remained closed for the duration of the interview (25-30 minutes). The average air temperature reading recorded by the interviews using the thermometers provided was 5.9oC. (It should be noted that the thermometer used by interviewers (Figure 13) was a ‘domestic’ one, which would not have been as accurate as the datalogger used in the more detailed study described below in Section 4.2).

Figure 13 Example image of thermometer placement in respondent refrigerator.

20 The survey design was such that a specific figure was requested rather than a range. 21 In eight cases the temperatures recorded by the interviewers were not legibly noted and were therefore excluded from the analysis. 22 Given differences in styles of thermometer along with associated variability in accuracy and type of gauge, these results should be treated with caution.


Food waste While most respondents stated that they did not throw any of the specific food items away unopened on a frequent basis, a significant number across all the items did so occasionally (Figure 14).

Figure 14 Disposal of food items unopened (Base: Buyers of food items).

Disposal of cooked meats was relatively high (42%) as was the disposal of chilled ready meals (38%). Responses across all the items indicate that there is a significant opportunity to address food waste at a domestic level e.g. by improving storage, encouraging freezing and better planning. Again, across all the items there were a significant number of respondents who stated that they sometimes disposed of these items after they’d partly consumed but not finished them (Figure 15).

Figure 15 Disposal of food items opened & partly eaten/drunk (Base: Buyers of food items).

The data indicates that the proportion of respondents disposing of cooked meats once opened is relatively high at 59% however it is possible that respondents will have included not only pre cooked meats e.g. sliced ham but also meat bought fresh and cooked at home.


4.1.3 Limitations of the study The survey design used a quota sampling approach. While this approach is frequently used in research of this type there are greater risks associated with bias and sampling error compared to random sampling methods. The limited number of households included in the survey also means that the sample should be regarded as a “typical” cross-section rather than a statistically representative sample of the GB population. Thus generalisations to the wider population cannot be made with confidence. The behaviours recorded in the survey are self-reported. This may have led to some of the reported behaviours being modified to some degree through the influence of having an interviewer present during completion of the survey. As already noted the thermometers provided by Campden BRI to the interviewers for use during the survey (Figure 21) was a ‘domestic’ one, which would not have been as accurate as the datalogger used in the more detailed study described below in Section 4.2. 4.1.4 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


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

6.7

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69

29.4

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39.3

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84.9

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Fresh Meat Fresh Fish Cooked Meats Bacon Chilled Ready Meals

% o

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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.


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).

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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.


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).

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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).


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). 4.2.4 Comparison with other studies A review of survey work carried out to determine domestic fridge temperatures has been undertaken (Campden BRI, 2004. Evaluation of product shelf life for refrigerated foods, Guideline No. 46). This showed that five domestic fridge air temperature surveys had been carried out, all of them between 1990 and 1992.


A survey of 75 households recorded that mean operating temperatures were <5°C (Rose, S.A., Steadman, S. and Brunskill, R. (1990). A temperature survey of domestic refrigerators. CCFRA Technical Memorandum No. 577. Campden BRI).

A MAFF survey of 252 households recorded mean operating temperatures of 6°C, with 22% of fridges at temperatures >8°C (James, S.J. and Evans, J. (1992). Consumer handling of refrigerated foods: temperature performance. International Journal of Refrigeration, 15 (5), 299-306).

A survey of 150 domestic fridges recorded average operating temperatures of 6.5°C. It was also noted that 26% of larder fridges and 29% of freezer-box fridges operated at average temperatures above 8°C (Flynn, O.M.J., Blair, I. and McDowell, D. (1992). The efficiency and consumer operation of domestic refrigerators. International Journal of Refrigeration, 15 (5), 307-312).

Temperature distributions were measured in empty and loaded fridges by James and Evans (1992) 'The temperature performance of domestic refrigerators'. International Journal of refrigeration, 15 (5), 313-319. When loaded with foods at 5°C, mean temperatures ranged from 0.3-8°C on the top shelf and 2-3.7°C in the fridge door. Average temperatures of two fridges loaded with food at 20°C for 4 hours showed that mean temperatures ranged from 10.8-12°C.

The in-home temperature survey completed as part of this research shows that the majority of domestic refrigerators operate at a mean temperature of around 7°C. It was apparent 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. The average temperature reading across the whole survey population, as recorded by the interviewers, using the thermometers provided was 5.9oC. As part of the FSA’s ‘Forward Evidence Plan’27 a larger scale survey of domestic refrigerator temperatures in the UK is being considered, which would build on the current research. This new survey will provide evidence to support the Agency’s food hygiene messaging, assess whether refrigerator temperatures have changed since the last survey, inform risk assessments for microbiological hazards in the domestic kitchen and provide information for manufacturers on consumer practices and conditions for storage of chilled foods.

27 http://www.food.gov.uk/multimedia/pdfs/evidenceplan10.pdf


5.0 Experimental programme at Campden BRI 5.1 Controlled domestic fridge temperature study For these tests, six fridges were used under laboratory controlled conditions (e.g. temperature and humidity measurements, fridge loading, door opening and environmental conditions) and the factors affecting temperature distributions were determined. 5.1.1 Method summary The six fridges chosen for this test encompassed, as far as practicable, a range of makes, models and designs. This included two identical larder fridges, two fridges within integrated fridge-freezers, an 'American-style' fridge and a fridge with integrated icebox. The objectives of these tests were to measure the typical temperature /humidity distributions within domestic fridges, when filled with a model food load and subjected to a series of controlled door opening/closing actions. Table 4 indicates the fridges used for this test along with their main design features and technical specifications. The volumes quoted represent the volume of the fridge and are taken from the rating plate found on the fridge. None of the fridges had circulation fans - all relied on natural circulation of air in the fridge.

Table 4 Fridges used in the controlled laboratory tests.

Fridge no. Shelf Energy rating

Refrigerant Setting* Volume Fridge type***

1 Glass 100 W 55g R600a

3 152 litres Fridge freezer (The fridge

compartment was on top)

2 Wire 85 W 120g R134a

4 135 litres Fridge freezer (The fridge

compartment was on top)

3** Wire 55 W 17g R600a

4½ 135 litres Larder

4** Wire 55 W 17g R600a

4 135 litres Larder

5 Wire 70 W 20g R600a

3 132 litres Icebox

6 Glass 140 W 88g R600a

5°C 352 litres American

* The setting used on the fridge for these tests was set to provide a nominal fridge temperature of 5°C. The temperature was marked directly on the display for fridge 6. ** Two identical models of larder fridge were chosen to give an idea of not just inter-model variability, but also variability between identical appliances. Note the fact that to get a nominal fridge temperature of 5°C the two fridges required a different setting, suggesting variability in the operation of the thermostats. *** The makes/models have been anonymised.


5.1.2 Results – temperature distribution Figure 23 shows the fridge air temperature distributions within Fridge 1 (fridge freezer). During the night-time operation (no door opening), the average temperatures ranged from 1.8°C (middle shelf, back) to 9.3°C (top shelf, front). During daytime operation (door opened for two minutes each hour for six hours), average temperatures for these periods ranged from 2.3°C (middle shelf, back) to 10.6°C (top shelf, front).

Figure 23a Temperature distributions within Fridge 1 (fridge freezer) (night).

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Figure 23b Temperature distributions within Fridge 1 (fridge freezer) (day).

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Figure 24 shows the fridge air temperature distributions within Fridge 2 (fridge freezer). During the night time operation (no door opening), average values of the temperature ranged from 5°C (middle shelf, back) to 8.7°C (top shelf, front). During daytime operation (door opened for two minutes each hour for six hours), average temperatures for these periods ranged from 6.7°C (middle shelf, back) to 9.7°C (top shelf, front).

Figure 24a Temperature distributions within Fridge 2 (fridge freezer) (night).

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Figure 24b Temperature distributions within Fridge 2 (fridge freezer) (day).

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Figure 25 shows the fridge air temperature distributions within Fridge 3 (larder fridge). During the night time operation (no door opening), average values of the temperature ranged from 1.4°C (middle shelf, back) to 9.1°C (top of door). During daytime operation (door opened for two minutes each hour for six hours), average temperatures for these periods ranged from 1.8°C (middle shelf, back) to 5.5°C (top of door).

Figure 25a Temperature distributions within Fridge 3 (larder fridge) (night).

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Figure 25b Temperature distributions within Fridge 3 (larder fridge) (day).

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Bottom Sheld (Salad Crisper)

Bottom of door shelf

Top of door shelf


Figure 26 shows the fridge air temperature distributions within Fridge 4 (larder fridge). During the night time operation (no door opening), average values of the temperature ranged from 4.8°C (middle shelf, back) to 8.4°C (base of door). During daytime operation (door opened for two minutes each hour for six hours), average temperatures for these periods ranged from 4.9°C (middle shelf, back) to 9.8°C (base of door).

Figure 26a Temperature distributions within Fridge 4 (larder fridge) (night).

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Figure 26b Temperature distributions within Fridge 4 (larder fridge) (day).

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Figure 27 shows the fridge air temperature distributions within Fridge 5 (icebox fridge). During the night time operation (no door opening), average values of the temperature ranged from 5.2°C (top shelf, centre) to 10.5°C (salad crisper). During daytime operation (door opened for two minutes each hour for six hours), average temperatures for these periods ranged from 6.3°C (top shelf, back) to 11°C (top shelf, front).

Figure 27a Temperature distributions within Fridge 5 (icebox fridge) (night).

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Figure 27b Temperature distributions within Fridge 5 (icebox fridge) (day).

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Base of Door

Top of Door


Figure 28 shows the fridge air temperature distributions within Fridge 6 (‘American’ style fridge). During the night time operation (no door opening), average values of the temperature ranged from 4.6°C (middle shelf) to 6°C (top shelf). During daytime operation (door opened for two minutes each hour for six hours), average temperatures for these periods ranged from 4.6°C (middle shelf) to 6.5°C (top shelf).

Figure 28a Temperature distributions within Fridge 6 (‘American’ style fridge) (night).

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Time (mins)

Temperature (°C) Top Shelf Front Left

Second Shelf Back Right

Third Shelf Front Right

Third shelf Back Centre

Forth Shelf Middle Left

Fifth Shelf Left Middle

Middle of Door

Salad Crisper

Figure 28b Temperature distributions within Fridge 6 (‘American’ style fridge) (day).

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Temperature (°C)

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Second Shelf Back Right

Third Shelf Front Right

Third shelf Back Centre

Forth Shelf Middle Left

Fifth Shelf Left Middle

Middle of Door

Salad Crisper


The increased air temperature in fridges during the daytime is a result of both the higher ambient air temperature during the day and the increased frequency with which the door is opened. This highlights the importance of locating the fridge in a suitable place within the kitchen - away from radiators or other sources of heat e.g. ovens, hobs, grills or the ventilation outlet of microwave ovens. The fridge should also have access to an appropriate airflow to assist in dissipation of the heat removed from the food by the fridge; the rear of the fridge often has coils mounted externally to assist with airflow. Fridges which are built into kitchen units should be installed so as to allow adequate airflow around the fridge. The booklet produced by MAFF (Ministry of Agriculture, Fisheries and Food) in 1984 'Keeping food cool and safe' (extract shown in Figure 29) highlights a number of useful pointers in relation to keeping food cool. This includes advice on where the coldest part of the fridge might be, which foods should be kept in which locations within the fridge and keeping the coldest part of the fridge cold enough for safe food storage. The results of this research were consistent with the results of the earlier work. The conclusions that can be derived from this work are: Consumers should check their fridge temperatures with a fridge thermometer and not assume the fridge

temperature dial correlates to fridge temperature. Temperature dials traditionally carry numbers relating to the degree of cooling, but not actual temperature, and there is often confusion whether increasing the number increases or decreases the fridge temperature.

As air temperature is not consistent across the whole cabinet, a single point temperature measurement in the fridge may not provide adequate information for the consumer. It is recommended that two or three temperature points are used - top, middle and bottom of fridge and then the consumer can ensure temperature sensitive products (such as uncooked meats and pre-prepared foods) are placed in the coldest part of the fridge.

The central areas of the fridges tested were generally the coldest. Current advice to consumers to load the fridge with uncooked meats, fish and ready meals in these areas of the fridge should be re-emphasised.

Quantifying actual temperature ranges within the fridge and mapping this (along the lines of the 'Keeping food cool and safe' booklet) would help consumers minimise food safety risks, improve food quality and reduce waste of refrigerated foods. A simple illustration could be produced graphically within the fridge or included as part of the fridge manufacturers hand book.

Modern fridges are increasingly designed to be more energy efficient, as a response to environmental legislation and consumer demands. This increase in energy efficiency is largely gained through the use of better insulation, which should have the additional benefit of maintaining a more stable temperature.


Figure 29 Extract from 1984 'Keeping food cool and safe' booklet showing where the coldest part of a domestic fridge is likely to be.


5.1.3 Results – fridge shelf construction The effects of different fridge shelf constructions were also investigated, using the two fridge-freezers (Fridges 1 and 2). Figure 30 shows the temperature fluctuations at the centre of two fridge freezers, one having a wire shelf and one a solid glass shelf. With the wire shelf, temperature within the fridge rose from 5°C to over 12°C on opening the door, taking some 35 minutes after door closure to recover a fridge temperature of less than 5°C. With the solid glass shelf, temperature within the fridge rose less, by just a couple of degrees, but also took around 40 minutes to recover to a fridge temperature of less than 5°C.

Figure 30a Temperature fluctuations with different fridge shelves (wire shelves).

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90 100 110 120 130 140 150 160

Time (mins)

Temperature (°C)

Middle Shel f Left Front Middle Shel f Center

Figure 30b Temperature fluctuations with different fridge shelves (glass shelves).

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The large gap between the two dataloggers in the glass shelf test (Figure 30b) showed that the glass (solid) shelf had an effect that 'stratified' the temperature throughout the fridge (i.e. could create different temperatures at different levels). Whereas the wire shelves (open) enabled air to flow freely between the top and bottom of the fridge, the solid shelves sometimes created layers of different temperatures. It is expected that this could have advantages and disadvantages - an open shelf would allow temperature to equalise more uniformly throughout the entire fridge but any changes e.g. door opening or placing a warmer food in the fridge etc. would help raise the temperature of the entire fridge. Conversely, a solid shelf would perhaps create very different temperature layers in different parts of the fridge. However, for any changes due to door opening, warm food etc. glass shelves would isolate the effect from some areas within the fridge.


These results suggest that glass shelves may help maintain a more consistent temperature over time within the fridge and can be used to minimise rapid temperature rises. This aspect of work will be considered more fully under the ‘fridge design’ part of this report (Section 6). Data28 would suggest that the majority of UK fridges have glass shelves (approximately 90%). 5.1.4 Results – humidity Humidity was also measured using the two fridge-freezers (Fridges 1 and 2). Figure 31 shows the humidity profiles measured in these two fridge freezers. Both profiles show a cyclic pattern. The cycling of humidity (peaks and troughs) relate to the frequency of the thermostatic temperature control used in the fridge (the temperature results also showed that one of the test fridges operated within a narrower temperature range than the other; Figures 4 and 5). During night time operation, the average mean dew point temperature29 in both fridges dropped (Figure 31a). Fridge 1 dropped to around -7°C and Fridge 2 to around -1°C. Both of these levels represent quite a dry environment. During day time operation (Figure 31b), when the door was opened each hour, humidity levels were higher as warm, moist air was let into the fridge.

28 Beijing Inforce Consulting Ltd, July 2009 29 The Dew Point Temperature is the temperature at which condensation will start to occur.


Figure 31a Humidity profiles within two models of Fridge freezer (night)

Figure 31b Humidity profiles within two models of Fridge freezer (day)

NB. It is not clear why the spike occurred (Figure 12b - between 100 and 150 minutes). From the results of humidity measurement (and also temperature measurement) it appears that spikes in temperature or humidity do occur from time to time and for no apparent reason – it is suspected that sometimes the thermostat doesn’t kick in to regulate temperature (which would have the effect of producing the humidity spike). It is possible that the thermostat used to control the fridge temperature is located in a place where it doesn't pick up the fridge temperature as quickly as the temperature dataloggers used in these experiments. In a fridge, humidity levels are generally lower than the surrounding environment as the moisture in the air condenses on the cooled surfaces within the fridge and then is drained away. From the results, although differences in humidity were found between the two fridges, they are not thought to be significant. It is likely, however, that a greater number of fridges would show a wider range of humidity conditions. During the course of the experiments, Campden BRI determined that the humidity levels within the fridge will indeed have an effect on the likely quality of the refrigerated food stored in the fridge. This will be more pronounced with foods that are unwrapped. Generally, fridges with low humidity levels (drier environments) will


tend to dry out the surface layers of some foods, particularly high moisture food (e.g. leftover meal components) and also foods higher in fats (e.g. cheese, hams, meats). The result is often that the food looks spoiled. In all circumstances, it is preferable to wrap the food - either in its original packaging (re-closing the packaging) or in an air-tight container. This would also have the effect of helping to mitigate any changes in temperature that might occur when the fridge door is opened. In contrast to this, it is well understood that high humidity can encourage mould growth so wrapping some foods can cause them to spoil prematurely. Foods which are respiring and giving off water, such as fruit and vegetables, need to be stored carefully as sealed wrappings can lead to moisture building up around the foods. Such items need to be stored in packaging with vent holes; the original packaging will be designed to meet this need. 5.1.5 Limitations of the study The experiments were not designed to align with ISO standards, which set out test methods for household refrigerating appliances, but to simulate a real life environment. Hence, the controlled domestic fridge study tests air temperature rather than product temperature as this is what the consumer will measure using most domestic thermometers. 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. This study has provided a snapshot of domestic fridge air temperatures and humidity under controlled conditions of measurement. Although six disparate fridges have been used for these tests, it is likely that a wider study, encompassing more models and types of fridge, would be useful to further reinforce the conclusions from this work.


5.2 Domestic fridge thermometer evaluation A separate study undertaken for WRAP by Campden BRI evaluated a wide range of domestic fridge thermometers available to the UK consumer. The results of this work are presented in a separate report30 with an overview of the results given below and summary table repeated in full (Table 5). A wide range of domestic fridge thermometers are available. The majority are liquid-in-glass, electronic, liquid crystal or bimetallic thermometers. These are widely available in most hardware stores, online and in larger supermarkets. The retail price of thermometers ranges from under £2 for the simple liquid crystal or liquid-in-glass types to over £25 for some electronic types. Given the low price options, fridge thermometers are a very affordable tool for consumers to ensure their fridge is operating at the correct temperature and to map temperature ranges so temperature sensitive foods can be stored in the right place. From a desk-based review of literature and web-based sources, a total of 18 different domestic fridge thermometers were purchased for this study, representing the range currently available to UK consumers. They were purchased from a variety of sources, including mail order catalogues, internet suppliers, magazine advertisements and in-store. These included eight versions of liquid-in-glass fridge thermometers, three versions of bimetallic fridge thermometers, five versions of electronic fridge thermometers, one version of a liquid crystal fridge thermometer and one version of an infrared fridge thermometer. The accuracy of the fridge thermometers tested was generally good, with the majority of devices measuring fridge air temperatures to within ±0.5°C of the actual fridge temperature31. Some of the fridge thermometers tested were not designed to directly measure fridge air temperature. One type had a standard liquid-in-glass thermometer embedded into a clear liquid gel; this was designed to slow down the rate of temperature change of the thermometer and be more representative of the temperature change actually experienced by the food products within the fridge. Another type used an infrared sensor to directly measure the food product/packaging temperature within the fridge and responded much more quickly than the other thermometers. All of the thermometers had scales that spanned a much wider range than was necessary for domestic refrigerator use, this made the proportion of the scale that was of interest to the consumer (typically 0-10°C) small as a proportion of the entire range, which consequently made the thermometers more difficult to read and less precise than the ideal. This is something for consideration by fridge thermometer manufacturers. The readability and usability of the thermometers varied considerably. While the electronic thermometers could be read easily and accurately (and in most cases they could be read without opening the fridge door) the liquid in glass thermometers were generally considered to be the most difficult to read as the design meant they often had to be looked at closely to determine the reading. This may lead to inaccuracies as a consumer may have to remove the thermometer from the fridge to read it, which in turn may affect the displayed reading. The instructions provided to consumers alongside the fridge thermometers were limited and quite variable. Many fridge thermometers were supplied with no instructions. Although some had an indication of recommended fridge temperatures and some provided advice on how to position the thermometer in the fridge the instructions for all the thermometers could be vastly improved to ensure that they are used by consumers in the right way and give accurate readings. Given the importance of good temperature control, the fact that fridges will not be a consistent temperature throughout and that the dial doesn’t correlate to temperature, fridge thermometers are an important and cost effective tool to support good refrigerated food storage. The recommendations from this work are for: Retailers (grocery and white goods retailers) to stock fridge thermometers either in the refrigerated food aisle

or signposted from the refrigerated food aisle. The food industry and government to use their communication channels to highlight the importance of good

temperature control in-home i.e. setting the fridge at the right temperature by using a fridge thermometer to check two or three temperature points and reiterate the importance of storing temperature sensitive foods in the coldest part of the fridge.

Thermometer manufacturers to improve the design to ensure that they span an appropriate range, limit reader error and contain clear instructions for optimal use.

Fridge manufacturers to design new fridges with a means of indicating the temperature as standard including linking the actual temperature to the fridge dial.

30 A performance assessment of domestic fridge thermometers, WRAP, 2009. 31 For this test, each of the fridge thermometers were placed in a controlled-temperature cold room environment at a nominal 'chilled' temperature of between +2 and +5°C. The air temperature immediately surrounding each of the thermometers was monitored using thin bare-wire thermocouples (type K, nickel-chromium) attached to a temperature datalogger (Squirrel datalogger, Grant Instruments Ltd).


Table 5 Summary of the results of the domestic fridge thermometer testing programme. Therm. number

Image Operating principle

(manufacturer)

Therm. price

Accuracy (based on testing programme)

Scale Readability Comments

1

Liquid in glass (Brannan)

£2.50 Measured temperature to within ±0.5°C of the

reference temperature

-40 to +30°C 1°C divisions 70 divisions in

total

1°C error possible if scale is not viewed straight

(parallax error)

2

Liquid in glass (Brannan)

£2.50 Measured temperature to within ±1°C of the



total


(parallax error)

3

Liquid in glass (ETI)




total


(parallax error)

On-pack guidance suggests fridge

should be set to 3-5°C

4

Liquid in glass (Unbranded)




total

0.5°C error possible if scale is not viewed

straight (parallax error)

No instructions were supplied

5

Liquid in glass (Endotherm)


reference temperature. Large thermal lag,

took appreciably longer than the others to reflect changes in temperature (heating and cooling)


total


(parallax error)

Large potential error in reading

6

Liquid in glass (Food Safety Direct)



-30 to +50°C 10°C divisions 8 division in

total

2-3°C error (parallax error and estimation of scale)



7

Liquid in glass (Foodsafe)


reference temperature. Large thermal lag, took appreciably longer than

the others to reflect changes in temperature (heating and cooling)


total


(parallax error)


8

Liquid in glass (Chef Aid)




total


(parallax error)

9

Bimetallic £3.50 Measured temperature to within ±1°C of the



total

0.5°C error possible if scale is not viewed

straight (parallax error)

No instructions were supplied

10

Bimetallic (Food safety Direct)




total

3-4°C error (parallax error and estimation of scale)


11

Bimetallic (ETI) £1.80 Measured temperature to within ±0.5°C of the



total


(parallax error)

12

Electronic (Multi Thermo)



-50 to +150°C 0.1°C resolution

0.1°C (possible error when temperature is rounded to 1 decimal

place).

13

Electronic (Digitron)



-30 to +40°C 1°C resolution

1°C (possible error when temperature is rounded to

0 decimal place).


14

Electronic (ETI) £6.80 Unable to measure temperature to within ±1°C of the reference

temperature

-9.9 to +49.9°C 0.1°C resolution


place).

Unable to measure temperature to

within ±1°C of the reference

temperature

15

Electronic (ETI) £14.00 Measured temperature to within ±0.5°C of the


-39.9 to +69.9°C

0.1°C resolution


place).

16

Electronic (ETI) £7.50 Measured temperature to within ±0.5°C of the


-39.9 to +69.9°C

0.1°C resolution


place).

17

Infrared surface (Fluke)

£57.00 Unable to measure temperature to within ±1°C of the reference

temperature

-30 to +200°C 0.1°C

resolution. LED highlights above 60°C and below

4°C


place).

Unable to measure temperature to

within ±1°C of the reference

temperature

18

Liquid crystal (Coldzone)

£1.58 Coldzone indicators changed from showing

‘OK’ when the environment temperature was in the range 1°C to 2°C to a blank indication when the environment temperature was above

3°C to 4°C

NA Specification says that "OK" is displayed at

temperatures less than +5°C

Risk of fridge being set at too low a

temperature


6.0 Innovative domestic refrigerator design to improve food temperature control

Having quantified domestic fridge temperature data and the common practices of consumers in the use of fridges for refrigerated foods, this section will highlight the current and future opportunities in fridge manufacture and technology that may improve food temperature control. Many of these are promoted as a means of improving food safety and quality, helping to reduce waste in refrigerated foods. 6.1 Current fridge design Almost all fridges work on a vapour compression cycle where a volatile liquid is compressed and then cooled by passing it through an external arrangement of tubing, the liquid is then passed through a restriction valve and it expands and cools before being compressed again. The compressor, and hence 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. The thermostat is generally located inside the refrigerator cabinet, on the inside wall close to the door. For most fridges the temperature can be adjusted simply using a dial which gives indicative numbers. Consumers should consult their fridge manual to determine whether a higher number on the dial means the fridge temperature will become colder after being adjusted or visa versa. More modern fridges sometimes have a temperature display showing the running temperature within the cabinet but it is often not clear at which point in the fridge this temperature is measured. 6.2 Ideas to improve refrigerated food storage 6.2.1 Improvements in temperature control Most fridges are controlled using simple on-off thermostats that regulate the temperature. These work well but are normally set up with a large degree of hysteresis i.e. a wide band between when they turn on and turn off. This results in a distinct cycling of temperature as seen in Figure 32 though, as earlier data shows, when the fridge is operated correctly the average temperature will still fall between 0-5°C.

Figure 32 Typical temperature cycling of domestic refrigerator.

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Top Shelf Back LeftTop Shelf Centre

Top shelf Front RightMiddle Shelf Front LeftMiddle shelf centre

Middle Shelf Rear RightBottom Sheld (Salad Crisper)Bottom of door shelf

Top of door shelf

Source: Results from larder fridge, data collected as part of earlier experiment.


Traditional European static fridges that have a cold wall construction are set up to eliminate the need for the customer to initiate the defrosting of the fresh food storage compartment. Thus by allowing the temperature in the cabinet to rise to a value of about 7°C it ensures the melting of the frost on the cold wall before the thermostat re energises the compressor. In a frost free construction product where the compartments are cooled by forced air circulation from a remote evaporator (typical US type) it is possible to have a narrower band of temperature fluctuation since the defrosting of the evaporator is not carried out in a food storage compartment. An alternative way of controlling the fridge temperature has been introduced on some premium products, the so-called ‘inverter’ control. Instead of the controller only being able to switch the compressor on and off, this system can regulate the speed of the compressor. This enables a much finer control of the fridge temperature and should eliminate temperature fluctuations. As the temperature approaches the set-point, the amount of cooling provided by the system can be reduced and the compressor will be run at a rate that matches the heat gain of the refrigerator and will never be switched off, leading to a more stable temperature. The temperature probes used in refrigerators could also be improved to react faster to temperature changes such as when the door is opened. The design of fridges with a vertically hinged door mean that as soon as it is opened, the cold air within the fridge is allowed to ‘fall’ out and is rapidly replaced by warm air from the top. The warm air then has to be cooled when the door is shut. During the period of controlled door opening (Section 3.1.2) the fridge temperatures rose significantly from the ‘stable’ temperature and took between 30-60 minutes to recover. Alarms to indicate if the door has been left open are a feature of some fridges currently on the market. They are also available as stand alone devices that can be fitted to any type of free-standing appliance (Figure 33). Given the low cost of such devices and the potential benefits (energy saving and improved temperature stability) this is something that could be made universal.

Figure 33 FA-DUAL; a fridge or freezer door alarm with a built-in time-delay with a digital display LCD thermometer.

Some new fridges have been designed with alternative door designs that help to minimise the effect of door opening such as the ‘American’ style fridge (Figure 34), which has a small door that can be opened to allow access to frequently needed items, keeping the rest of the fridge sealed. The use of drawers on some refrigerator models (see next section, Figure 35) can also help to improve temperature control as the cold air will be trapped around the products by the drawer. This should have the effect of reducing cold air loss and warm air entry and this should minimise temperature fluctuations. Some high end products use auto door closers when the door is left open a few degrees which might not be discernible to the user.


Figure 34 'American' style fridge.

On a newly launched premium fridge (Fisher and Paykel Cool drawer) the user can specify the temperature of up to five separate zones within the fridge, to ensure that specific products are kept at the optimum temperature. This is currently retailing at around $2200, making it out of reach for most consumers, but could become more accessible over time. 6.2.2 Improvements in accessibility of fridge items One of the challenges to the consumer is to store all the food they have purchased in a way that reduces the possibility of cross contamination (e.g. raw meat next to cooked products) yet allows each product to be accessed or seen so that a duplicate item is not purchased or the existing one forgotten about. The design of most fridges is very similar, with a space to store tall items in the door and a combination of shelves and drawers in the main body of the fridge to store the rest of the items. Most fridges have shelves that can be seen through, to allow consumers to see and find items when they have been pushed to the back. Older and budget fridges generally have wire mesh shelves and newer or premium models tend to have glass shelves. However, shelf depth and height may mean some parts of the fridge are not very accessible, particularly when it’s full. New designs of fridges that have been launched have attempted to improve the accessibility of the food using different combinations of doors or drawers (Figure 35). This should make it easy for the user to see all of the items in the fridge, hopefully improving ‘stock’ rotation and management. Drawer use is common in Japan where they store fresh fish and need compartments with distinctive temperature profiles.


Figure 35 Fridge design with drawers

6.2.3 Innovations launched by manufactures to improve food storage life Panasonic have introduced a ‘vitamin-safe’ compartment for the storage of fresh fruit and vegetables32. This is a clear drawer that is illuminated when the fridge door is closed. Blue and green LEDs are used to imitate sunlight and prolong the life of fresh fruit and vegetables. In this drawer, the humidity can be controlled to protect produce from drying out. Panasonic have also introduced the ‘Hygiene Active System’ to clean the air in fridges and minimise the transfer of odours from one item to another. This is a combination of filters and UV light that is used to clean the air as it is distributed around the fridge. NEFF have developed an innovative preservation system ‘VitaFresh’33. It is a 0°C compartment independent from the fridge temperature setting comprising two humidity zones. The dry section maintains 50% humidity to preserve meat and fish whilst the moist zone at 90% humidity extends the life of vegetables, salads and fruit. In these conditions nutrients and vitamins of food are preserved for longer. Storage of separate foods within these zones also prevents intermingling of smells.

32 http://www.panasonic.co.uk/html/en_GB/Products/Fridge-Freezers/NR-B30FG1/Overview/2134089/index.html 33 http://www.neff.co.uk/VitaFresh.html


6.3 ‘Blue sky’ ideas for improving the storage of refrigerated foods. Technology is currently available that could improve the use of fridges and minimise waste; however, it is likely to be some time before it is implemented or adopted. This section of the report highlights existing design solutions to help maintain food temperature control. 6.3.1 Intelligent monitoring of shelf life Radio Frequency Identification Data (RFID) tags are small electronic tags that can be incorporated onto the surface of the product. They can be interrogated by close contact with a suitable aerial coil. Simple tags can provide identification information (this could be used to scan a whole basket of shopping at once). More advanced ‘active’ tags can monitor the condition of a food and give information about transport temperatures or vibration. If active tags were set up to monitor product temperature throughout the product life, they could be used to calculate the shelf life for an individual product. This would take into account temperature abuse in the chill chain or from the retailer to the consumer and the effect of storage temperature on produce quality. In this way the shelf life for each individual product could be calculated and could indicate when the product is no longer fit to consume. 6.3.2 Product identification RFID tags could also be used to manage the fridge contents via a computer system. The fridge computer would register each item as it was placed into the cabinet. This would allow the fridge contents to be monitored which could enable a variety of new developments such as: Stock control - a user could be alerted when a certain item had been used and needed to be re-ordered. It

could also give a record of how long certain items had been in the fridge for and which one should be used first.

Shopping list generation - if a fridge system managed the items within it, it could be used to suggest shopping lists, working on the basis of ‘this item is no longer in the fridge, so more needs to be ordered’.

Recipe suggestion - if a system knew the contents of the fridge, it could be linked to a database of recipes and could be set to suggest ideas for meals that you have all the ingredients for.

Intelligent temperature control - a fridge could be set to control temperature and humidity to prolong the shelf life of its contents. This would enable the most efficient use of energy (it wouldn’t cool areas that were empty) and choose the conditions that maximised product shelf life.

6.3.3 Air curtains Air curtains could be used to generate a ‘wall’ of air that reduced the entry of warm air when the fridge door was opened. They are currently used on most retail display cabinets so that the products are accessible yet stay at the correct temperature.


7.0 Recommendations This project has surveyed the consumer handling of refrigerated foods, in particular the effects on temperature of transporting the refrigerated food from the supermarket to the home and storage in the domestic fridge. It has also surveyed and quantified actual temperatures in a range of domestic fridges and conducted a series of controlled laboratory tests to ascertain the control of temperature achieved in a range of different fridge types and an evaluation of domestic fridge thermometers. A key part of this project was an extensive survey of refrigerated food practices in the home, the results of which provide an insight into consumer food purchasing, food storage, fridge ownership and management of food items. This study has generated a number of key observations regarding the consumer use of fridges and a series of recommendations across the supply chain that could be explored to help consumers keep what they buy at its best in the fridge and prevent food waste. These are summarised below: Food manufacturers Simplify the labelling of products with respect to storage conditions on-pack aiming for a common approach

whereby manufacturers should choose to label with a choice of two phrases relating to temperature, i.e. either “Keep Refrigerated”34 or “Store at 5°C maximum”. This is in line with CFA guidance35 and would help reiterate the correct fridge temperature (of below 5°C) and highlight which are temperature sensitive products.

Extend the use of reclosable packaging, particularly for products like cheese and cooked meat and, where possible, make it clear that the packaging is helping to keep the food fresh because the fridge is a dry environment.

Food retailers Increase the availability and visibility of tools such as fridge thermometers and ‘cool-bags’ in-store, for

example, by selling them in the refrigerated food aisles. Include tips and guidance, for example, at point of sale or incorporated into recipe card materials, highlighting

the importance of good temperature control. Increase consumers’ knowledge of the link between optimal storage, particularly in regard to keeping refrigerated food at the right temperature, and keeping food fresh. Such materials could also make consumers aware of humidity levels within the fridge and the importance of wrapping/reclosing opened packs or storing them in air-tight containers.

White goods manufacturers Investigate developing an industry standard for whether turning the dial up or down reduces or raises the

temperature or as a minimum make it clearer for any given fridge which direction produces a cooler or warmer temperature. It would be helpful if the industry could take steps to start producing fridges where the numbers on the dial reflect the temperature. In moving towards this objective it is recommended that higher numbers reflect higher temperatures.

Reinforce the importance of keeping the fridge at the right temperature, with tips on using a fridge thermometer and regularly measuring the temperature, for example, graphically within the fridge or within the manufacturer’s handbook.

Include illustrations, for example, graphically within the fridge or within the manufacturer’s handbook, of where the coldest part is likely to be together with guidance on which temperature sensitive foods should be stored there. Continue to increase the proportion of manufacturer handbooks available online, and include a simple “one page” summary \ pull-out on-line and in hard copy of the relevant use and storage advice.

Develop point of sale material to highlight the importance of good temperature control, fridge humidity and using a fridge thermometer.

Increase the number of new fridges (even basic designs) that have an integral thermometer. The temperature indicator should ideally be visible to the consumer even when the door is closed. The suitability of integral alarms, that sound when the temperature rises above a certain level, could also be investigated.

Fridge thermometer manufacturers Ensure all thermometers are sold with clear instructions for use e.g. what temperature the fridge should be

run at, good practice on how regularly the temperature should be measured and at how many locations in the fridge.

34 From a manufacturing perspective, chilled food labelling of ‘keep refrigerated’ is taken to mean an 8°C maximum, targeting 5°C. In reality, most commercial chill chains will operate well towards the lower end of this regime. The larger temperature range reflects the fact that residency time in the supply chain is relatively short. Consumer facing messages should, however, only refer to a temperature range of 0-5°C. 35 Labelling of storage requirements on pack, CFA, 1996 (http://www.chilledfood.org/MEDIA/POSITION+STATEMENTS/temperature)


Develop thermometers that are specifically for fridge use and have a scale that is appropriate to the temperature range likely to be found in a domestic fridge; and is therefore easy to read.

White goods retailers Stock tools such as fridge thermometers and fridge door alarms alongside fridges. Include tips and guidance, for example, at point of sale, highlighting the importance of good temperature

control.

WRAP / FSA Update the survey of domestic refrigerator temperatures in the UK (e.g. as proposed under the FSA’s

‘Forward Evidence Plan’36. Use the Love Food Hate Waste (www.lovefoodhatewaste.com) campaign and Eatwell (www.eatwell.gov.uk) to

reinforce messages about: The importance of good temperature control in-home and between leaving the supermarket and home for

refrigerated foods e.g. setting the right fridge temperature and using a cool bag etc. The fact that fridges do not have a consistent temperature throughout, providing good practice guidance

for measuring fridge temperatures (how often and at what locations). The likely humidity levels within refrigerators and the effect on food products e.g. the importance to

wrap/seal food after opening, using packaging in the right way. What should be kept in the fridge and which are temperature sensitive and should be stored in the coldest

part of the fridge.

WRAP will work with the food and white goods sector through the Courtauld Commitment37 and Home Improvement Sector Commitment38 to take forward these recommendations. Success would help both improve food safety in the home and could reduce food spoilage associated with poor storage that could lead to waste.

36 http://www.food.gov.uk/multimedia/pdfs/evidenceplan10.pdf 37 http://www.wrap.org.uk/retail/courtauld_commitment/index.html 38 http://www.wrap.org.uk/retail/home_improvement/index.html


Appendix 1 Quotas set for the Consumer Survey

Table 1 Socio-economic status.

Socio economic status

Quota %

AB 24 C1 28 C2 21 DE 28

Socio-economic groups are based on the head of the household or chief income earner and are defined as follows: A: Higher managerial, administrative or professional B: Intermediate managerial, administrative or professional C1: Supervisory or clerical, and junior managerial, administrative or professional C2: Skilled manual workers D: Semi and unskilled manual workers E: All those entirely dependent on the state long term, through sickness, unemployment, old age or other reasons. Table 2 Lifestage.

Lifestage

Group Quota

% Pre-family/no family 28

Family 27 Third Age 26 Retired 20

The lifestage groups are defined as follows: Pre-family/no family: aged under 45 who are not parents Family: any age with at least one child aged under 16 still at home Third Age: aged 45-64 with no children aged under 16 Retired: aged over 65 with no children aged under 16

Table 3 Region.

Region (TV Area)

Quota %

London 20 South 9

Anglia/Midlands 24 South West/Wales 11

Yorkshire/ North East 16 North West 12 Scotland 9

Interviews were carried out in 28 locations distributed across the above regions as follows: Farnborough, Hants; Farnham/Guildford, Surrey; Camberley/Frimley, Surrey; Southampton, Hants; Staines, Mddx; Lewisham, London; N. Petherton, Somerset; Keynsham, Bristol; Cardiff; Chepstow ; Market Deeping, Lincs; S. Pickenham, Norfolk; Hucknall, Notts; Long Eaton, Notts; Mansfield, Notts; Langley Mill, Notts; Lutterworth, Leics; Blackpool, Lancs; Rochdale, Lancs; Oldham, Lancs; Shotts, Scotland;


Whitburn, Scotland; Carluke, Scotland; Newcastle-on-Tyne; Washington, Tyne & Wear; Bridlington, Yorks; Leeds, Yorks; Sheffield, Yorks. Participants were selected at random in each of these interview points and pre screened to ensure that certain criteria were met notably that they were either individually or jointly responsible for household main grocery shopping; that they most often purchased the household main grocery shopping from a supermarket; that they had a working electric refrigerator at home and that they purchased and stored chilled prepared foods in a refrigerator.


Appendix 2 Analysis of Consumer Survey Population Just under half (49%) of the survey population were aged 18-44 years and 87% of all those interviewed were female. In line with the quota requirements, 53% of the survey population were social grade ABC1. Just over four in ten participants (42%) were working full time, with 21% working part time and 20% non working. The survey population by lifestage reflected the quota requirements. Two thirds of participants lived in households with two adults permanently living in the household, 18% were single adult households.

Figure 1 Respondent Age Profile (Base n= 329).

7.3

18.5

23.4

18.5

14

18.2

0

10

20

30

40

50

18‐24 25‐34 35‐44 45‐54 55‐64 65+

Per

cen

tag

e

Age

Figure 2 Respondent Lifestage Profile (Base n= 329).

24.6

29.527.7

18.2

28 27 26

20

0

10

20

30

40

50

Pre fam Family Third Age Retired

Pe

rce

nta

ge

Lifestage

Actual Quota


The survey population in terms regional profile reflected the quota requirements. Just under three quarters of participants (74%) were themselves responsible for undertaking the household main grocery shopping and just over eight out of ten respondents (82%) were themselves responsible for deciding where to store food items on returning home from the main shop.

Figure 3 Respondent Region Profile (Base n= 329).

19.5

8.5

24.3

10.6

15.812.2

9.1

20

9

24

11

1612

9

0

10

20

30

40

50

Lond South Ang/Mids S W/Wal Yorks/N E N West Scot

Pe

rce

nta

ge

Region

Actual Quota


Appendix 3 Detailed Results from the Consumer Survey Food Purchase Practices Q1a Do you generally carryout a regular major food shop? Overall, nearly nine out of ten (88%) participants stated that the generally carried out a regular major food shop. Q1b How often do you usually carry out your main food shopping for your household? Of those undertaking a regular major shop, most (70%) usually carried out this shop once a week with a further 15% usually conducting a main food shop a couple of times a month. The results indicate that a higher proportion of the pre family and family groups conduct their main shopping once a month compared to the other two lifestage groups.

Figure 1 Usual Frequency of main food shopping trip (Base n= 289).


Table 1 Usual frequency of main food shopping trip.

All

respondents Pre family Family Third Age Retired

N= 289 %

69 %

90 %

79 %

51 %

Every 2 -3 days

7.6 7.2 7.8

7.6

7.8

About once a week

70.6 63.8 70.0

79.7

64.7

A couple of times a month

15.2 20.3 11.1

11.4

21.6

Once a month

6.2 7.2 11.1

1.3

3.9

Less often

0.7 1.4 0

0

2.0

Q2a On which day do you usually carry out your main food shopping trip? The most frequently cited shopping days were Saturday (18%), Friday (17%) and Thursday (11%) respectively however just over three in ten respondents (32%) stated that their main shopping day varied. This latter finding was lower among the retired lifestage group.

Table 2 Day usually carry out main food shopping trip.

All


N= 289 %

69 %

90 %

79 %

51 %

Monday 7.6 10.1 5.6 7.6 8.0 Tuesday 4.5 1.4 3.3 5.1 10.0

Wednesday 6.6 1.4 10.0 7.6 6.0

Thursday 11.1 2.9 10.0 12.7 22.0

Friday 17.4 17.4 16.7 15.2 22.0

Saturday 18.1 24.6 16.7 19.0 10.0

Sunday 4.2 5.8 5.6 3.8 0

Variable 31.9 36.2 33.3 31.6 24.0 Q2b And is this day usually one of the following? Among those respondents working and undertaking a main shop, nearly 24% conducted their main food shop on a working day, 40% on a day off work and 36% either on a working or non working day. Table 3 Type of day usually carry out main food shopping trip.

All respondents

N= 202 %

A working day 23.8

A day off work 40.0

Variable 36.0


Q2c And what time of day do you usually carry out your main food shopping trip? The most frequently cited time for conducting the main shop was in the morning (36%) followed by afternoon (24%) and evening (14%) but for nearly a fifth of respondents (18%) the time of day for conducting a main shop varied. Table 4 Time of day usually carry out main food shopping trip.

All respondents N= 289

% Early morning 0.7

Morning 35.6 Mid day 8.0

Afternoon 23.5 Evening 13.8

Late evening after 10pm 0 Variable 18.3

Q3 How do you usually make the journey to carryout your main food shopping trip? For 90% of respondents the car was the mode of transport usually used for the main shopping trip. Table 5 Type of transport usually used to carry out main food shopping trip.


% Car 90.3 Bus 3.5

Train 0 Bicycle 0 Foot 4.2 Taxi 1.7

Motorbike 0.3 Q4 Approximately how long is it usually between completing the shop and unpacking your shopping for main food shopping trip? Across all respondents, over four out of ten (45%) of respondents stated that their usual journey time took between shopping and unpacking was up to 30 minutes, with a further 23% stating this was between 30 minutes to one hour. Around a quarter of the survey population stated that the duration between shopping and unpacking was between 1 -2 hours (with potential significant implications for the temperature of chilled foods as just over 12% used a cool bag/box to bring home chilled foods – see Q17), with the remaining respondents taking two hours or more.


Figure 2 Duration of shopping to unpacking main food shopping (Base n= 289).

Table 6 Duration of shopping to unpacking main food shopping.


% Up to half an hour 45.3

Half to hour 22.8 1 to 2 hours 25.3 2 to 4 hours 6.2

More than 4 hours 0.3 Q5 How often do you find that your journey home/unpacking your shopping is delayed by visits to relations, friends, sport or any other engagements? Most respondents (63%) stated that they usually journeyed straight home after the main shop although 33% stated that their journey was delayed from time to time by engagements etc. Table 7 Any delays between completion of main food shopping trip and unpacking.


% Always 0.7

Very frequently 3.1 Sometimes 10.0

Rarely 23.2 Never 63.0


Q6 When did you last do your main food shopping trip? Nearly 6% of the survey population had completed their main shop on the day of the interview, 13% on the previous day and a further 13% two days previously. Around a third had completed their main shop 3-4 days prior to the interview and 35% 5-6 days prior to the interview.(Note that interviewers were instructed to complete the interview as close as possible to the day of the respondent's main shop). Table 8 When carried out last main food shopping trip.


% Today 5.5

Yesterday 13.1 Two days ago 12.8 3-4 days ago 33.2 5-6 days ago 35.3

Q7 How often do you visit the shops (other than your main shop) to pick up small quantities of food (top up shopping) for your household? Nearly 15% of all respondents stated that they visited the shops daily to carry out top up shopping with a further 56% visiting every 2 - 3 days. The pre family group appeared less likely to conduct top up shopping daily, whereas the retired group appeared less likely to conduct top up shopping. A Pearson chi-square test confirmed that the frequency variation by lifestage was statistically significant at the 5% level of significance (P value = 0.018). Figure 3 Frequency of top up food shopping (Base n= 329).

14.6

55.9

19.5

2.7 0.90

10

20

30

40

50

60

70

80

90

100

Every day Every 2‐3 days

Once a week Twice a month

Once a month

Per

cen

tag

e

Frequency


Table 9 Usual frequency of top up shopping.

All


N= 329 %

81 %

97 %

91 %

60 %

Everyday 14.6 8.6 19.6 16.5 11.7 Every 2 - 3 days 55.9 59.3 62.9 51.6 46.7

About once a week 19.5 25.9 14.4 18.7 20.0 A couple of times a

month 2.7 2.5

0 3.3 6.7

Once a month 0.9 0 1.0 1.1 1.7

Less often 1.2 2.5 0 2.2 0

Never 5.2 1.2 2.1 6.6 13.3 Q8 When doing top up shopping is this usually on one of the following days? Among working respondents undertaking top up shopping, around two thirds (67%) stated that this day was usually variable. Perhaps not surprisingly given the often unplanned nature of top up shopping that this was almost twice the equivalent result recorded in respect of the main shop (36%). Table 10 Type of day usually carry out top up food shopping.

All respondents

N= 236 %

A working day 29.2

A day off work 4.0

Variable 66.5

Q9 And what time of day do you usually carryout your top up shopping? Again not surprisingly the most frequently cited time of day for conducting top up shops was that it varied (37%), twice that of the equivalent result recorded for the main shop (18%). Just over a fifth of respondents (23%) stated that they usually conducted top up shopping in the morning, 18% in the afternoon and 16% in the evening.

Table 11 Time of day usually carry out top up food shopping.


% Early morning 0.3

Morning 22.8 Mid day 6.4

Afternoon 17.6 Evening 15.7

Late evening after 10pm 0 Variable 37.2


Q10 How do you usually make the journey to the shops to carryout the top up shopping? While the car was the mode of transport usually used for top up shopping (69%), a much higher proportion (25%) made the journey by foot compared to the equivalent result in respect of the main shop (4%). Table 12 Transport usually used for top up food shopping.


% Car 69.2 Bus 3.8

Train 0 Bicycle 1.3 Foot 25.0 Taxi 0.3

Motorbike 0.3 Q11 Thinking of your top up shopping approximately how long is it usually between completing the shop and unpacking your shopping? The usual duration time between shopping and unpacking was shorter than the main shop with just over six in ten (63%) of those conducting top up shopping stated that their usual journey time was up to 30 minutes (the equivalent result among for the main shop was 45%). A further quarter (27%) of respondents stated that the usual journey time was between 30 minutes to one hour. (A Pearson chi-square test confirmed that the frequency variation between the main shop and top up shop was statistically significant at the 5% level of significance (P value = 0.000)). Figure 4 Duration between shopping to unpacking top up food shopping (Base n= 312).


Table 13 Duration of shopping to unpacking top up shopping.


% Up to half an hour 62.5

Half to hour 27.2 1 to 2 hours 7.4 2 to 4 hours 1.6

More than 4 hours 1.3 Q12 And thinking of your top up shopping, how often do you find that your journey home/unpacking your shopping is delayed by visits to relations, friends, sports or any other engagements? Similar to the main shop pattern of responses, most respondents (63%) stated that they usually journeyed straight home after the top up shop although 33% stated that their journey was delayed from time to time by engagements etc.

Table 14 Any delays between completion of top up shopping trip and unpacking.


% Always 0.6

Very frequently 3.2 Sometimes 11.5

Rarely 21.2 Never 63.5

Q13 Where do you usually shop for the following foods? (This does not include any frozen foods) Respondents were asked which type of shop (main supermarket, small grocer, specialist shop ie butcher, farm shop, milkman, cash & carry) they usually purchased from in respect of a number of food items. Among buyers of each of the food items, a main supermarket was the primary usual outlet used across all the food items. However, in respect of fresh meat buyers (96% of the survey population), 15% cited that they usually used a specialist shop. In respect of milk buyers (all respondents bar one), around 8% usually used a milkman and a further 8% a small grocer/local shop. Among egg buyers (98% of respondents), just over 8% cited that they used a farm shop. Fresh fish was the item that recorded the most non purchasers (22%) although again among buyers the main supermarket was the primarily outlet used, although just over 7% of buyers used a specialist shop. Across the lifestages, although supermarkets were still the primary outlet, there was a relatively lower occurrence of the use of supermarkets among the retired group for these food items compared to the other lifestage groups.


Figure 5 Those using the supermarket for selected food items (Base: 329).

Table 15 Where usually shop for following foods.

Base n=329

Not purchased

Main supermarket

Small grocer/local

shop

Specialist shop

Farm shop

Milkman

Cash & Carry

Other

Milk % 0.3 83.8 7.0 0.3 7.9 0 0.6

Cheese % 1.5 97.0 0.3 0.3 0.6 0 0 0.3

Chilled Ready Meals % 2.4 95.7 0.9 0 0 0 0.9

Fresh meat % 4.0 77.5 1.2 14.6 0.9 0 0.3 1.5

Fresh fish % 21.6 70.1 0 6.1 0 0 0.3 1.8

Cooked meats % 3.3 91.8 0.6 3.6 0.6 0 0 0

Bacon % 7.3 87.2 1.2 2.1 1.2 0 0 0.9

Apples % 3.6 87.2 3.6 3.0 1.5 0 0 0.9

Carrots % 3.0 89.4 2.1 2.7 1.8 0 0.3 0.6

Eggs % 2.4 80.2 1.8 2.7 7.9 0.9 0.3 3.6 Q14 Do you buy any of the following items with the intention of freezing them? Around eight to nine out of ten buyers of milk, cheese and cooked meats stated that they never purchased these items with the intention of freezing them. Whereas fresh meat and fresh fish were the items most cited by buyers of these items as regularly purchased to freeze (37% and 29% respectively), and at lower levels, 17% of bacon buyers and 14% of chilled ready meal buyers. However, half of chilled ready meal buyers (51%) stated they occasionally bought this food item with the intention to freeze, 44% of fresh meat buyers, 41% of fresh fish buyers and 38% of bacon buyers.


Table 16 Items bought with the intention of freezing them.

Base n= 329 Regularly Occasionally Never Not

purchased

Milk % 3.0 4.9 91.8 0.3

Cheese % 1.8 7.3 89.4 1.5

Chilled Ready Meals % 12.8 49.5 35.3 2.4

Fresh meat % 35.3 42.6 18.2 4.0

Fresh fish % 22.2 31.9 23.7 21.6

Cooked meat % 3.3 11.6 81.8 3.3

Bacon % 15.8 35.3 41.6 7.3


Food Storage Practices Q15 Where do you store the following foods when you get then home? Almost all milk, cheese and cooked meat buyers and nearly nine out of ten chilled ready meal buyers (90%) and bacon buyers (88%) stored these items in the refrigerator (the remaining respondents in respect of these two items stored them in the freezer, which was also true for three out of ten fresh meat and fish buyers). Apples, if not stored in the fridge, were stored by 38% of buyers on a kitchen work top or vegetable basket in the light (27%). Carrots if not stored in the fridge were stored in vegetable baskets, some in the light (13%), or in the dark (11%), whereas eggs if not kept in the fridge were stored on a kitchen work top by 19% of buyers. Figure 6 Those storing selected food items in the fridge (Base: buyers).

99.1 99.7

89.7

72.8 71.1

98.7

87.9

22.1

64.270.9

0

20

40

60

80

100

Mi lk CheeseChi l led

Ready

Meals

Fresh

Meat

Fresh

Fish

Cooked

meats

Bacon ApplesCarrots Eggs

Pe

rce

nta

ge

sto

rin

g in

fri

dg

e

Food types

Table 17 Where food items stored.

Base n = 329

Not purchased

Refrigerator

Food cupboard in the kitchen

Larder/garage or room

outside the kitchen

Kitchen work top

Vegetable basket/rack in

the light

Vegetable basket/rack in

the dark

Freezer

Other

Milk % 0.3 98.8 0.6 0 0 0 0 0.3 0

Cheese % 1.5 98.2 0 0 0.3 0 0 0 0 Chilled ready meals

% 2.4 87.5 0 0 0 0 0.3 9.8 0

Fresh Meat % 4.0 69.9 0 0 0 0 0.3 25.8 0

Fresh Fish % 21.6 55.5 0 0 0 0 0 22.6 0

Cooked Meat % 3.3 95.4 0 0 0 0 0 1.2 0

Bacon % 7.3 81.5 0 0 0 0 0 11.2 0

Apples % 3.6 21.3 1.8 2.1 36.5 25.8 4.0 0.3 4.6

Carrots % 3.0 62.2 3.4 3.7 4.0 12.2 11.0 0 0.6

Eggs % 2.4 69.2 5.2 1.2 18.6 0.6 1.2 0 1.5


Q16 And how do you usually store the following foods when you get them home? Just over eight out of ten apple buyers (85%) stored this item loose (ie removed from packaging); this was true for 56% of carrot buyers, although not surprisingly egg buyers were more likely to store this food item in the original packaging (57%).

Table 18 How food items stored.

Base: Buyers

In original packaging/bag if

bought loose

Loose (removed from packaging)

Apples (317) - % 15.5 84.5

Carrots (320) - % 44.4 55.6

Eggs (321) - % 57.1 42.9

Q17 Do you use a cool bag/box to bring chilled foods home? As noted earlier only 13% of all respondents used a cool bag/box to bring chilled foods home. This varied markedly between lifestage groups with only 6% of the pre family group using this item, 9% of the family group, 15% of the third age group and 22% of the retired group. A Pearson chi-square test confirmed that the frequency variation by lifestage was statistically significant at the 5% level of significance (P value = 0.027). The use of a cool bag/box had a limited corresponding relationship with the time taken between completing and unpacking the main shop as 25% of the pre family group took more than 1 hour, among the family group this was 33%, 37% of the third age group but only 31% of the retired group.

Table 19 Use of cool bag/box.

All


N= 329 %

81 %

97 %

91 %

60 %

Yes 12.5 6.2 9.3 15.4 21.7 No 87.5 93.8 90.7 84.6 78.3

Q18 Which food items do you put into a cool bag/box to bring home? Of the ten selected food items apples, carrots and eggs at 5%, 7% and 10% respectively were the least likely items to be placed into a cool bag/box. The other items ranged from 63% (fresh fish) to 88% (cheese).

Table 20 Items placed into cool bag/box.

Base = 41

%

Milk 78.0

Cheese 87.8

Chilled ready meals 61.0

Fresh meat 78.0

Fresh fish 63.4

Cooked ready meals 73.2

Bacon 70.7

Apples 4.9

Carrots 7.3

Eggs 9.8


Q19 When you’ve bought the following foods how long do you usually expect to be able to keep them (without freezing them)? Among buyers who provided a response, cheese followed by eggs were cited as having the longest expected storage from the time of purchase. Storage expectations for chilled ready meals were 3.6 days on average, 2.8 days for fresh meat and 1.8 days for fresh fish. Storage expectations for apples at 7.5 days and carrots at 7.2 days seemed relatively short. Looking at the relationship between how items are stored (Q15) and (Q19), apples and carrots had the most varied storage conditions. The mean storage time among those storing apples in the fridge was slightly higher (around a day) than under other conditions; the same was recorded for carrots when compared to storage in a vegetable basket in the light. Figure 7 Average (in days) food storage expectations from time of purchase? Base = buyers of each item.

Table 21 Storage expectations for selected food items – Base 329.

Up to 1 day

Up to 2 days

Up to 3 days

Up to 4 days

Up to 5 days

Up to 6 days

Up to 7 days

Up to 8 days

Up to 9 days

Up to 10 days

Up to 11 days

Up to 12 days

Up to 13-14 days

Up to 21 days

Up to 30 days

Milk % 0 4.3 17.9 17.3 15.8 4.6 27.4 0.9 1.2 4.6 0.3 0 2.7 0.6 1.2

Cheese % 0 0 1.2 3.0 3.6 1.5 23.7 1.5 1.2 7.9 0.9 1.5 24.0 11.6 16.4 Chilled Ready

Meals% 5.2 23.1 23.1 12.2 10.0 1.2 18.2 0 0 0.9 0 0 2.1 0 0

Fresh Meat % 6.7 30.4 26.7 13.4 7.6 0.9 9.4 0.3 0 0.3 0 0 0 0 0

Fresh Fish% 24.8 28.5 13.8 4.9 1.8 0.3 3.7 0 0 0 0 0 0 0 0 Cooked Meats% 0.3 9.4 16.7 14.0 12.2 5.2 29.5 1.8 0.6 2.4 0 0 3.6 0 0

Bacon% 0.6 4.0 6.1 7.0 7.9 2.4 29.3 2.7 0.6 7.6 0 0.3 14.3 4.6 4.3

Apples% 0 0.6 3.6 6.4 9.7 4.9 42.9 3.6 1.5 6.1 1.5 1.2 9.4 1.5 2.1

Carrots% 0 1.8 4.0 9.5 9.1 3.7 41.5 3.0 2.4 7.3 1.8 0.6 7.9 1.5 1.5

Eggs% 0.3 0 0.6 1.5 2.4 1.2 31.3 2.1 2.7 12.5 4.0 2.4 24.6 6.1 4.3


Q20 And once opened and partly eaten how do you store these items? How items were stored once opened varied across the nine food items. Not surprisingly milk is usually stored by almost all respondents (96%) in its original packaging in the fridge. The storage of opened cheese was more variable with just over a third of buyers (34%) storing the product in its original packaging in the fridge, and a further 40% in the fridge but in an alternative wrapping. Nearly a fifth (19%) stated that they decanted this item into an airtight container. In terms of chilled ready meals, most respondents either kept the product in the fridge in its original packaging (41% - rising to 51% of the retired age group) or disposed of the product if not completely finished (42%). Fresh meat was fairly equally stored in the fridge either in original packaging or in an alternative wrapping although nearly a fifth (19%) would dispose of the item if not completely finished (11% among the pre family lifestage where almost twice as many than the survey average said that they would store the item decanted into an airtight container). In respect of fresh fish just over two fifths (42%) would dispose of the item if not finished. The storage of cooked meats was similar to that of cheese in that 42% of buyers stored the product in its original packaging in the fridge, and a further 37% in the fridge but in an alternative wrapping. Just over 11% decanted the food item into an airtight container In terms of apples, the majority (63%) stored this item out of the fridge with 19% in the fridge in some format, while 56% stored carrots in the fridge in the some format.

Table 22 How food items stored once opened.

Food Item (Buyers)

In fridge in original

packaging

In fridge out of original

packaging

In fridge out of original packaging but

in alternative wrapping

In fridge decanted into airtight container

Out of Fridge

Wouldn't keep/store it if I didn't finish it all

Milk (n=327) %

96.0 3.1 0.3 0 0.6 0

Cheese (n=323) %

34.1 7.1 40.0 18.9 0 0

Chilled Ready Meals (n=320) %

41.9 3.8 8.4 3.8 0 42.2

Fresh Meat (n=315) %

30.5 8.3 32.4 9.5 0.6 18.7

Fresh Fish (n=256) %

24.6 6.3 22.3 5.1 0 41.8

Cooked meats (n=318) %

41.8 8.8 36.8 11.3 0 1.3

Bacon (n=304) %

39.5 6.9 33.9 17.8 0 2.0

Apples (n=316) %

5.4 12.3 1.0 0.3 63.3 17.7

Carrots (n=318) %

20.4 32.1 2.8 0.9 31.1 12.6

Q21 And once opened and partly eaten how long would you usually expect to be able to keep the following foods? Not surprisingly across all the food items, expectations of average storage duration fell once opened and partly eaten compared to when unopened. The most significant difference was recorded for chilled ready meals where storage expectations fell by more than half and may explain the relatively high proportion of buyers who disposed of the product if not completely finished (42% - Q20). A decline in storage expectations was also noticeable in respect of fresh meat, bacon and fresh fish. There was evidence that storage expectations once opened varied by how respondents stored the items. For example respondents storing the cheese and fresh meat items in a fridge in an alternative wrapping had longer storage expectations than those storing them in a fridge in the original packaging.


Figure 8 Average (in days) food storage expectations from purchase unopened (Q19) and once opened and partly eaten (Q21) (Base = buyers of each item)

5.3

12.8

3.62.8

1.8

4.9

8.4

7.5 7.2

10.4

4.2

9.2

1.4 1.61.1

3.4

4.8

6.5 6.2

0

10

20

Milk Cheese Chilled

Ready Meals

Fresh Meat Fresh Fish Cooked

meats

Bacon Apples Carrots Eggs

Me

an

Nu

mb

er

of

Da

ys

Food types

Mean Mean - Open

Table 23 Storage expectations for selected food items once opened and partly eaten – Base 329 (non buyers/and don’t knows not shown).

Up to 1 day

Up to 2 days

Up to 3 days

Up to 4 days

Up to 5 days

Up to 6 days

Up to 7 days

Up to 8 days

Up to 9 days

Up to 10 days

Up to 11 days

Up to 12 days

Up to 13-14 days

Up to 21 days

Up to 30 days

Milk % 1.2 11.2 29.2 18.5 11.6 4.9 15.8 1.2 0.3 3.0 0 0.6 1.5 0 0.3

Cheese % 0.3 1.5 4.0 4.0 9.7 2.4 35.6 1.2 1.2 7.0 0.9 3.0 16.7 4.6 6.1 Chilled Ready

Meals% 49.8 22.0 7.6 4.9 0 0.3 2.8 0.6 0 0 0 0 0.3 0 0

Fresh Meat % 33.5 34.8 14.9 4.6 2.7 0.9 0.9 0 0 0 0 0 0 0 0

Fresh Fish% 45.3 21.7 4.6 1.2 0.9 0.3 0.6 0 0 0 0 0 0 0 0 Cooked Meats% 3.3 20.4 25.2 19.1 12.5 3.6 8.8 0.9 0.6 0.9 0 0.3 0.6 0.3 0

Bacon% 2.4 11.9 13.4 13.1 13.7 5.5 20.4 2.4 1.8 2.7 0.6 0 2.4 0.3 0.6

Apples% 10.9 0.9 3.0 5.5 6.7 4.0 36.2 1.8 1.5 4.9 2.7 1.8 7.0 0.6 1.2

Carrots% 7.3 4.6 6.7 7.3 7.6 4.3 32.3 2.1 1.8 5.5 1.5 1.2 8.2 0.6 0.3

Q22 Do you defrost food in the fridge? Around 35% of the survey population stated that they defrosted food in the fridge. Just over a further quarter of the survey population (26%) stated that they sometimes defrosted food in the fridge. No statistically significant differences were recorded between lifestages.

Table 24 Defrost food in the fridge.

All

respondents N=

329 %

Yes 34.7

No 39.8

Sometimes 25.5


Q23 Do you follow the storage advice eg' Keep refrigerated 'given on packaged foods? Around six in ten (60%) of all respondents stated that they always followed storage advice on packaged foods with a further 34% some of the time. No statistically significant differences were recorded between lifestages.

Table 25 Follow storage information.

All

respondents N=

329 %

All of the time 60.2

Some of the time 34.0

Never 5.8

Q24 How helpful do you personally find the current methods eg best before dates of providing people with advice on when to eat food? Nearly six in ten of all respondents (58%) found current advice methods on when to eat food extremely or very helpful. No statistically significant differences were recorded between lifestages

Table 26 Helpfulness of current advice methods on when to eat food.

All

respondents

N= 329 %

Extremely helpful 20.1

Very helpful 37.7

Moderately helpful 27.4

Slightly helpful 8.5

Not helpful 6.4

Q25 Is there any additional advice or information regarding home storage you would like to see included on food packaging? 65 respondents (19.8%) offered comments in terms of additional information that could be provided in relation to home storage. A list of the verbatim comments is shown in Appendix 1.


Refrigerator ownership & management of food items Q26 How many refrigerators do you have? Across the survey around 87% of respondents had one fridge, 12% two and just over 1% three fridges. Not surprisingly the proportion with two or more fridges (4%) was markedly lower among the pre family lifestage group compared to the other lifestages. A Pearson chi-square test confirmed that the frequency variation by lifestage was near statistically significant at the 5% level of significance (P value = 0.054).

Table 27 Number of refrigerators.

All


N= 329 %

81 %

97 %

91 %

60 %

One 86.6 96.3 82.5 84.6 83.3 Two 11.9 1.2 16.5 14.3 15.3

Three or more 1.5 2.5 1.0 1.1 1.7 Q27a And where is your (main) refrigerator located? In terms of location, 92.7% of main fridges were located in the kitchen with a further 4.6% in a utility room, 0.9% in the garage, and 0.9% elsewhere. Q27b If applicable where is your second refrigerator located? 51.2% of second fridges were in the main located in the garage, 23.2% elsewhere, 14.0% in the kitchen and 11.6% in a utility room. Q28 Approximately how old is your main refrigerator? Nearly a third of all respondents (31%) stated that their fridge was more than five years old.

Figure 9 Age of main refrigerator (Base = 329).

8.212.8

15.5 14.316.4

30.7

0

10

20

30

40

50

Under a year 1‐2 years 2‐3 years 3‐4 years 4‐5 years 5+ years

Pe

rce

nta

ge

Years


Q29 What temperature do you think your refrigerator should be run at? It is encouraging that unprompted 79% of respondents correctly stated that the fridge should be run at between 0 to 5 0C, although just over 10% of respondents did not provide a response to this question.

Figure 10 What temperature should fridge be run at? (Base = 329).

2.1 2.7 2.14.9

15.8

27.4

17.6

11.2

4.9

11.2

0

10

20

30

40

50

‐2 ‐1 0 1 2 3 4 5 6+ NR

Per

cen

tag

e

Temperature

Q30 How do you know if your fridge is at the right temperature/cold enough? While encouraging that unprompted 79% of respondents correctly stated that the fridge should be run at between 0 to 5 0 C, when asked how they would know if their fridge is running at the right temperature, nearly six in ten respondents (unprompted) stated they relied on personal judgement ie 'if the food felt cold' . 19% of respondents stated that they would not know if the fridge is at the right temperature - this was particularly true among the older lifestages (24% among the retired group compared to 11% among the pre family group).

Table 28 How do you know if your fridge is at the right temperature/cold enough?

All

respondents N=

329 %

Food feels cold

59.9

Don’t know

18.5

Other

11.4

Manufacturers recommendation

5.9

I take a thermometer reading

5.6

Q31 Do you know how to change your fridge settings/temperature? Across the survey population, 90.6% stated that they knew how to change the fridge settings/temperature.


Q32 Do you change your fridge settings/temperature? Of respondents who knew how to change the fridge settings, 4.3% stated that they frequently changed the settings; 51.1% said that they sometimes changed the settings, while 34.3% said that they left the settings unchanged. (10.3% did not provide a response). Q33 Why do you change your fridge settings/temperature? Changing external temperatures were most often cited as the reason for changing the fridge temperature setting - 61% cited if the weather gets hotter and 34% if the weather gets colder. 23% said they would change the setting if the food doesn't feel cold and 14% depending on how full the fridge is.

Table 29 Why change refrigerator settings.

Base n= 182 those frequently/sometimes changing settings (Q32)

%

Weather gets hotter 60.9

Weather gets colder 34.1

Food doesn’t feel cold 23.1

Food going off too quickly 2.2

Thermometer reading 2.7

After cleaning the fridge 4.9

Depending on how full the fridge is 14.3

If its new to get setting correct 1.1

Other 7.7 Q34 The following statements are comments made by other people in respect of how they look after their refrigerator and its contents. Please select the level of agreement you feel best represents your view in relation to each statement. (Strongly disagree, Disagree, Neither agree/disagree, Agree, Strongly agree) Responses to the statements indicated that there are a number of fridge practices that have implications for food waste. Notably a significant proportion of the survey population (16%) agreed with the comment that fridge temperatures do not make much difference to how long food lasts. In addition a substantial number of respondents stated that they did not check the contents of the refrigerator before a major shop (either thoroughly or briefly) with the implication this may have on unnecessary food purchases.

Table 30 Agreement with attitude statements (Base n= 329).

Disagree Neither

agree/disagree Agree

Before a major food shop I usually thoroughly check the contents of the refrigerator

% 31.9 10.0 58.1 Before a major food shop I usually briefly check the

contents of the refrigerator% 39.3 11.6 49.1

I regularly (at least once a month) clean the inside of my fridge

% 19.1 10.0 70.8 I only clean the inside of the fridge if there is

something spilt% 67.8 8.2 24.0

I regularly (every few days) examine the contents of the fridge to check what needs to be eaten up

% 24.0 10.3 65.7 The fridge temperature doesn't make much difference

to how long the food lasts% 71.1 12.8 16.1


A one sample two tailed t-test was performed on the statements, to establish if there was a significant difference from the null hypothesis score of 3 (neither agree or disagree with the statement) where a score of 1 represents strongly disagree and a score of 5 represents strongly agree. All statements were significant at the 5% significance level apart from the statement 'Before a major food shop I usually briefly check the contents of the refrigerator'. (P value of 0.105) Q35 Thinking generally about the food you buy how often would you say that you throw these foods away without having eaten/drunk any of it? While few respondents stated that they threw any of the selected food items away on a frequent basis, a significant number across all the items did so occasionally. Disposal of cooked meats was relatively high (42%) as was the disposal of chilled ready meals (38%). Response across all the items indicates that there is a significant opportunity to address food waste at a domestic level. The Pearson correlation coefficient r and associated P value were calculated to establish the significance level of the correlation coefficient between food disposal (Q35 – ‘sometimes’) and storage expectations unopened in terms of mean days (Q19). No statistical significant correlation was identified.

Table 31 Disposal of food items unopened.

Food Item (Buyers)

Never Sometimes Frequently

Milk (n=328) %

78.7 18.9 2.44

Cheese (n=324) %

67.9 31.2 0.93

Chilled Ready Meals

(n=321) %

61.4 37.7 0.93


74.9 24.1 0.95


81.2 17.6 1.18


55.6 41.9 2.54

Bacon (n=303) %

78.5 20.8 0.66

Apples (n=316) %

66.5 32.0 1.58

Carrots (n=318) %

64.2 34.0 1.89

Eggs (n=320) %

73.1 26.3 0.63


Q36 And how often would you say that you throw these foods away when you've only eaten/drunk some of it/part of pack? Again across all the items there are a significant number of respondents who state that they sometimes dispose of these items when only partly consumed. In this format the proportion of respondents disposing of cooked meats is relatively high at 59% (however it is possible that respondents will have included in this item not only pre cooked meats but also meat bought fresh and cooked at home). The Pearson correlation coefficient r and associated P value were calculated to establish the significance level of the correlation coefficient between food disposal (Q36 – ‘sometimes’) and storage expectations opened in terms of mean days (Q21). No statistical significant correlation was identified although the correlation was stronger than that between Q35 & Q19. Table 32 Disposal of food items opened & partly eaten/drunk.

Food Item (Buyers)

Never Sometimes Frequently

Milk (n=328) %

63.9 33.3 2.8

Cheese (n=324) %

55.7 42.7 1.6

Chilled Ready Meals

(n=321) %

58.1 40.0 1.9


66.6 31.2 2.2


73.5 24.1 2.3


38.5 59.0 2.5

Bacon (n=303) %

62.5 36.2 1.3

Apples (n=316) %

53.3 42.9 3.8

Carrots (n=318) %

48.4 47.8 3.8

Eggs (n=320) %

66.7 32.1 1.3


Observational results, data recorded by interviewer Q38 Which of the following best describes the refrigerator? Across the survey population the majority of fridges were fridge/freezer combinations (58%) - with most having a fridge at the top with the freezer below. These fridge types were particularly evident among the pre family and family lifestages. Among the retired lifestage group, the proportion of stand alone fridges was significantly higher compared to the family lifestage group.

Table 33 Which of the following best describes the refrigerator?

All


N=

329 %

81 %

97 %

91 %

60 %

Fridge at top with freezer below

50.5 56.8

55.9

53.4

35.6

Fridge at bottom with

freezer at top

7.9 8.6

8.6

6.8

8.5

Stand alone fridge

38.6 33.3

34.4

39.8

55.9

Q39 Does the refrigerator have an external/internal digital temperature display? Interviewers were asked to note whether the fridge had an integral temperature display.14% of the survey population had an integral temperature display and from this group for 38 respondents (12% of the survey population), the temperature reading was captured. Those fridges with an integral display recorded an average temperature of 3.40 C, with a minimum of 1.00 C, a maximum of 7.00 C, and a standard deviation of 1.40 C. Q40 If thermometer present, what temperature is it reading? Interviewers were also asked to note whether the fridge had a thermometer present. Just over 9% had a fridge thermometer and from this group for 24 households, the temperature reading was captured. These thermometers recorded an average temperature of 4.50 C, with a minimum of 1.00 C, a maximum of 12.00

C, and a standard deviation of 3.20 C. (However, given differences in styles of thermometer along with associated variability in accuracy and type of gauge, these results should be treated with caution). Q41 If thermometer present, in which part of the refrigerator is the thermometer kept? Most of these thermometers (12) were located in the top part of the fridge with the remaining equally spread in either the middle, bottom or fridge door.


Q42 Please record the condition of the refrigerator seals around the door? In just over eight out of ten households (82%) the interviewers rated the fridge door seals as 'Excellent' or 'Good'.

Table 34 Condition of the seals around the refrigerator door?

All


N=

329 %

81 %

97 %

91 %

60 %

Excellent

43.5 44.6

45.7

52.3

38.3

Good

38.6 37.8

46.7

31.4

48.3

Average

12.2 17.6

7.6

14.0

13.3

Poor

0.6 0

0

0

0

Q43 Please record the refrigerator setting (% of the full setting) In 285 households data were captured on the temperature setting of the fridge. Among these households the average setting was recorded at 60% of the full setting. (However, given differences in styles of control settings along with associated variability in setting indicators - some were more difficult to read than others - these results should be treated with caution).

Figure 11 Example images of refrigerator control settings.


Q47 How full does the refrigerator appear to you? Across the survey population, in nearly one in five households (20%), the interviewers rated the fridge as completely full with a further 33% rated as three quarters full. There was little variation between the lifestage groups.

Table 35 Fullness of fridge

All


N=

329 %

81 %

97 %

91 %

60 %

Completely full

19.8 19.7

18.8

23.0

19.0

Three quarters full

33.4 33.3

33.3

34.5

36.2

Half full

29.2 23.5

31.3

32.2

32.8

Quarter full

11.6 17.3

13.5

6.9

8.6

Nearly empty

4.0 6.2

3.1

3.4

3.4

Q48 Using the thermometer provided and following the instructions provided please take the temperature inside the fridge? Before starting the interview, interviewers were instructed to place the thermometer provided flat on the middle shelf of the respondent's main fridge towards the back of the shelf. The fridge door then remained closed for 25-30 minutes, equating to the duration of the interview. The average temperature reading recorded by the interviews using the thermometers provided was 5.9 0C, the minimum was 1.0 0C, maximum 15.0 0C and standard deviation 3.1 0C. Q49/Q50/Q51/Q52 Interviewers were instructed to take digital photographs of the exterior and interior of respondents' fridges. A full set of images for each household was captured. A selected number are shown in the full report by lifestage to illustrate the nature of these images.


Appendix 4 Specifications of fridges used for consumer fridge temperature study

Household

code Age of appliance Type Supplier

Model number

Volume (litres)

1 Between two and up

to three years old Stand alone fridge BENKO LA 620 136

6 More than five years Stand alone fridge HYGENE - 159

15 More than five years Fridge at bottom

with freezer at top ZANNUSSI

FREEZONE ZFC 66/14

66

19 Between four and

five years Stand alone fridge HOTPOINT

ICED DIAMOND RLA V21

150

21 More than five years Stand alone fridge ZANNUSSI ZFT 57 RM 153 30 More than five years Stand alone fridge LG GR L207TQ 352


to three years old Fridge at top with

freezer below ELECTRA - -

32 More than five years Stand alone fridge PHILLIPS CRU 0.16

ECO 148

36 Between three and up to four years old

Stand alone fridge SCHREIBER 20063101604 233

38 Between four and

five years Fridge at top with

freezer below SERVIS IN 7055-65 264


Stand alone fridge BEKO TLS5480S 268


with freezer at top JMB 1801 160

62 Between one and up

to two years old Fridge at top with

freezer below ELECTRA E7316C 316

73 More than five years Fridge at top with

freezer below ARISTON - 155


freezer below SAMSUNG RL39WBSW 241


to three years old Fridge at bottom

with freezer at top DAEWOO

FR -143 WH /BL

140

86 Between four and

five years Fridge at bottom

with freezer at top ELECTROLUX RA515 127


to two years old Stand alone fridge BOSCH FD8605 289

93 Less than one year

old Fridge at bottom

with freezer at top HOTPOINT

ICEDD DIAMOND

RTA42 283



freezer below INCUSINE

XCP 05 10005852 APW63 IFF

113



KELVINATER KC1 371 DELUXE 3400030

50


freezer below DAEWOO

NO FROST MULTI

FLOW ERF 340A

248

121 More than five years Stand alone fridge PROLINE PLFZ56A 288



HOTPOINT ICED

DIAMOND 173



freezer below SAMSUNG

FROST FREE COOL

N COOL SRL3616B

104



freezer below INDESIT BAN 134NF 288



freezer below INDESIT BAN 127NF 260


freezer below NEFF FD7606 166

167 Between four and


freezer below HOOVER HFA29K 160


to two years old Stand alone fridge INDESIT MF03 108

176 Fridge at top with

freezer below WHIRLPOOL

COMPACT COMBI

135

177 Fridge at top with

freezer below BOSCH SUPER 169


with freezer at top HOTPOINT MISTRAL + 200


to two years old Fridge at bottom

with freezer at top HOTPOINT

ICE DIAMOND

259


to two years old Fridge at bottom

with freezer at top BEKO - 135


freezer below BEKO

NC751 CLASS N TYPE 1

140


Stand alone fridge NEFF GMBH 142


freezer below HOTPOINT

MISTRAL FF72

204


freezer below DAEWOO ERF334M 201


to three years old Stand alone fridge HOTPOINT

RLA54 MICROBAN

70



freezer below ICEPOINT ICE17855 116



freezer below HOTPOINT RFA52 152



freezer below DAEWOO

NO FROST MULTI FLOW

198

282 More than five years Stand alone fridge LEC - 254


to three years old Stand alone fridge DEDIETRICH BZ996UI 283


with freezer at top ZANUSSI - 113


freezer below HOTPOINT

ICE DIAMOND

RF68P -


freezer below INDESIT CS1180 89

This data is an extract of the data collected from the consumer surveys. All of the volumes have been converted to litres to allow comparison.

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Reducing food waste through the chill chain

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