Refrigeration of foods. Cold storage practice

The edibility of foodstuffs is prolonged by lowering the temperature, since this slows chemical reactions and breakdown by bacteria. Some products can be frozen, and when they are in the solid state all movement in the individual cells will cease, inhibiting further reactions. 

The decision whether to just chill or to freeze solid depends on the type of product and the length of time it must be stored. Freezing results in some structural change, since ice crystals are formed inside the cells, and the final foodstuff may be of different texture when thawed out. 

As a general rule, foods which are not to be frozen are handled and stored at a temperature just above their freezing point, providing this does no damage (exceptions are fruits such as bananas and lemons). Produce which is to be frozen must be taken down below the freezing point of the constituents. Since foodstuffs contain salts and sugars, the freezing process will continue down to -18°C and lower. 

A distinction must be drawn between the cooling process and subsequent storage. Careful control of temperature and humidity is 

Cooling and freezing cannot improve a product, and the hest that can he achieved is to keep it near to the condition in which it entered the cooling process. This means that only the hest produce should he used, and this should he as fresh as possible. (This general principle must, of course, be interpreted in the light of local conditions and needs. In some countries of the world, preservation in cold stores is essential to prevent wastage, regardless of the quality of the crop.) 

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