'Keeping foods cool is one of the ways in which bacterial growth may be restricted. Storing foods rich in nutrients in fridges (operating below 5°C) or in freezers (at -18°C ) is considered to be an effective means of stopping pathogens from multiplying within them. *

It is, however, not practical to keep such foods under refrigeration all the time. Foods are not refrigerated, for example when:

• purchased and taken home from the shops;
• taken in packed lunches to school;
• cooled down after cooking;
• being prepared for eating;

On occasions, such as these, it is very important to control the time element, which is another requirement for bacterial growth. Foods which are likely to support bacterial growth and particularly those which are ready-to-eat (and will therefore not be cooked which would destroy any pathogens which might have grown) should not be kept in the growth zone for long periods of time.

* Note: The law, in England and Wales, imposes a general requirement for food businesses to keep chilled foods below 8°C because most pathogens do not grow at this temperature; those such as Listeria which may multiply in cooler conditions, will do so only very slowly. In practice, most food businesses aim to keep food at 5°C or cooler to allow for a margin of error below the legal standard.

Practical steps can be taken to try to keep foods at as low a temperature as possible and thus minimise the time during which they could be in the growth zone, particularly at mid-range temperatures where rapid bacterial growth may occur.

• Select and buy chilled and frozen food at the end of the shopping session.
• Pack chilled and frozen foods together if appropriate but make sure that raw and cooked/ready-to-eat foods are kept apart, e.g. icecream, yoghurts, cheese and butter in one bag; frozen lamb mince, chilled pork chops, bacon and sausages in another.
• Take chilled and frozen foods home as quickly as possible.

• Make sure that foods (e.g. sandwiches, salads, etc.) which are prepared in advance, are stored overnight in the fridge (or even freezer if appropriate).
• Keep items in the fridge until the latest possible time i.e. take out just before leaving for school.
• Pack foods, keeping the cold items together. (Items which may be successfully frozen e.g. some sandwiches, cartons of juice, etc. may assist in keeping other foods cool.)
• Do not include any warm items which may raise the temperature of other foods.

• Take food out of the hot tray/pan in which it has been cooked.
• Remove to the coldest part of the kitchen.
• Slice, if appropriate, to reduce the density for cooling.
• Place in a shallow container to expose a larger surface area.

• Place container on a bed of ice or in cold water.
• Stir liquids to dissipate the heat.
• Place food in fridge once cooled.

• Prepare foods as close to the time that they are to eaten as possible.
• Return foods which are not to be eaten or cooked immediately, to the fridge for storage until required.

Use insulated cool bags for maintaining foods at low temperatures. These are particularly useful for packed lunches, picnics, outdoor parties, etc. where foods may otherwise warm quickly.