Accelerated Freeze Drying (AFD) – A process whereby food is frozen quickly creating tiny ice crystals. The food is then dried in a chamber (sublimation) so the tiny ice crystals evaporate without turning to a liquid.
Air Blast Freezing – Food passes through a chamber on a conveyor belt and is blasted with cold air producing frozen food which is then packaged
Aseptic Canning – Food is sterilised and then placed into a sterilised can which is hermetically sealed, cooled and labelled.
Cold Smoking – Fish is salted and then heated to 30°C in the presence of creosote and formaldehyde which reduces the decay of fish. This fish must be cooked further.
Cook Chill Foods – A method of food processing whereby the food is produced, cooked, pasteurised and then chilled e.g. carton of vegetable soup.
Cryogenic Freezing – Method of preservation where food is sprayed with or immersed in liquid nitrogen. The food is frozen quickly and results in excellent quality preservation.
Curing – When meat is injected with brine (salt and water solution) the colour develops in pork and the shelf life of the meat is extended. Potassium nitrate is usually injected
Dehydration – A process of preservation which removes the moisture from a food. The removal of moisture means micro-organisms cannot survive.
Fluidised Bed Freezing – A method of preservation. Food is placed in a chamber where cold air is blown in under the food. The cold air currents lift the food and it freezes mid air. This is used for small pieces of food such as peas.
Hot Smoking – Where fish is salted and then heated to 80°C in the presence of creosote and formaldehyde which reduces the decay of fish.
Irradiation – A method of preservation by which radioactive rays are passed through the food this increases shelf life by the destruction of enzymes and micro-organisms thereby delaying the ripening and sprouting of fruit and vegetables. It is also used for spices.
Modified Atmosphere Packaging (MAP) – Foods are sealed in a container packaging
where the composition of the air (CO2, O2 or N2) has been altered. This helps increase shelf life and reduces enzymic browning.
Plate Freezing – A preservation method where food is placed between two cold plates. Suitable for thin pieces of food.
Quick Freezing – Freezing food at -25oC in the fast freeze section of the freezer. As the food is frozen quickly small ice crystals are formed which cause the least amount of damage to cells. When thawing, fewer vitamins are lost and more texture and colour is retained.
Slow Freezing – When food is frozen at temperatures above -18°C. This is quite a slow method so water moves while freezing, resulting in large ice crystals forming. During thawing, the large ice crystals dissolve breaking cell walls and releasing vitamins. Slow freezing increases the risk of vitamin loss and effects the texture of food.
Vacuum Packing – Food, usually meat, is sealed in polythene bags. Once opened it must be treated as fresh.
Bottling – A preservation process by which food is heated in containers to a temperature high enough to destroy micro-organisms and enzymes. A vacuum is created on cooling to prevent re-entry micro-organisms.
Dry Products – Products that do not ‘go off’ easily and do not support microbial growth. They are usually stored in a press/cupboard which should be clean and dry.
Freezing – Method of preservation where food temperature is reduced below 0oC. The food is maintained as close as possible to the original fresh food
Immersion Freezing – Method of preservation where food is immersed in freezing brine, useful for food that is an unusual shape.