Low temperature methods Bacteria become dormant (don’t reproduce but are not dead). Bacteria are not destroyed by low temperatures and become active when the food warms up again.

Chilling and cook-chilling Chilling is used for foods like sandwiches and cream cakes. The food keeps for a short time and is stored between 1C and 5C. The low temperature slows down enzyme action and bacterial growth. Cook Chilling is used for ready meals. Food is cooked and cooled to 0C to 3C. Products have a shelf life of five days.

Freezing Freezing is used for prepared dishes, fruit and vegetables. It can be done commercially or at home. At home frozen foods should be kept at -18C. Some fruits and vegetables may need plunging into boiling water for a short time before freezing. This is called blanching. Quick freezing reduces the damage to the cells in the food. It forms small ice crystals, which reduces damage to cell walls.

Chillers and freezers To maintain the temperature of chillers and freezers Regularly monitor the temperature with a probe or by data logging Record the temperature and store for evidence. Use sensors and warning lights to warn of temperature rise Keep the door shut Check and maintain the seals Defrost regularly Do not over fill.

Consumer use Most food poisoning is caused by poor food transportation, storage and use at home. Frozen, chilled and cook chilled foods should be.... Transported home quickly Stored and cooked according to instructions Cook chilled dishes must be eaten within two hours of cooking Leftovers should not be reheated Frozen foods should not be refrozen.

Accelerated Freeze Drying Accelerated freeze drying is a combination of freezing and drying. Food is frozen quickly and then placed in a vacuum under reduced pressure. It is heated and the ice changes to vapour, leaving the food dry.AFD food is light and easily restored by adding water. There is little change to the flavour, colour and nutritive value. The foods can be kept at room temperature.