Flash freezing

The shock freezing or quick-freezing is used for gentle preservation of food in the production of frozen foods. Within a very short time (usually only minutes) lowered the temperature of the food to be frozen to the desired storage temperature ( -18 ° C). The procedure was developed in the early 20th century by Clarence Birdseye.

But only the subsequent compliance with the cold chain in accordance with frozen - regulation, avoidance of temperature fluctuations and a protection against dehydration ensures further quality preservation of frozen foods.

Benefits

Unlike the much slower freezing in home freezer, the cell liquid forms upon rapid cooling only very small ice crystals. Characterized the cell walls and membranes are not destroyed by organelles. Even when thawing, the cell structure is largely retained, the cells do not run out and certain ingredients (eg enzymes) remain separated in the organelles of the cell remaining liquid; Cell- water and nutrients are included, the inner pressure of the cell is maintained. Therefore, the food does not lose its consistency, is therefore not, for example muddy. Other properties such as the flavor development are also little deteriorated.

During slow freezing in a home freezer occur large ice crystals attributable problems especially in foods with high water content or thin cell walls (for example, when berries ).

Method

For shock freezing plate freezers, cold air freezer or cryogenic freezers are used depending on the type of food. All methods have in common that either the product has direct contact with the cold metal plate, or is surrounded with the corresponding cold air or other gases at high speed.

Contact freezing method ( plate freezers )

In this method, the packed food is placed between the metal plates, in which a refrigerant flows, which it is cooled to -40 ° C. This is extracted from the products very fast heat. Used this method for example, in fish fillets and spinach.

Cold air freezing method

The products that are frozen with this method is not withdrawn in a tunnel by moving air at -50 ° C the heat. Lighter products are thereby stirred up ( "Flow -freezing process"). This method is used for example in noodles.

Cryogenic process

In this method, the liquid refrigerant of carbon dioxide and nitrogen. The carbon dioxide ( -78 ° C) or nitrogen (-196 ° C) is in this case sprayed into a tunnel system in which on a tape which usually unpackaged foods are transported. For liquid carbon dioxide is formed at the moment of spraying in solid (dry ice) and gaseous carbon dioxide, which absorbs the heat from the refrigerated and is continuously extracted. The cryogenic process are especially suitable for meat and fish products and fruit and baked goods.