Methods of conservation of foodstuff
Conservation - processing of the foodstuff intended for storage, for the purpose of the prevention of the damage caused by microorganisms. At the heart of various methods of conservation of foodstuff the factors which influence results or in destruction of microorganisms, or to the time termination of their ability to live, or to suppression of activity of enzymes lay. Thus in one cases action low or a heat, in others ultra-violet and an ionising radiation, ultrasound, in the third - the raised osmotic pressure and concentration of hydrogen ions, dehydration, bactericidal substances is used.
Action of low temperature is a basis of such methods of conservation, as freezing and cooling. Freezing of foodstuff is based that the majority of microorganisms sensitively to action of low temperatures, and at-18 °s and more low development of microorganisms activity of enzymes and the physical and chemical processes connected with it in fabrics stops, decrease also. The great value thus has speed of freezing. At slow freezing water from cages gradually passes in intercellular space, forming large crystals of ice and damaging cages. If product freezing occurs quickly, water has not time to leave in intercellular space, ice crystals turn out small and product fabrics are not damaged. Therefore it is recommended to make freezing quickly, placing a product in special chambers with temperature more low-18 °s, and defrosting - slowly. Thus the liquid released during thawing of ice, back is absorbed in cages of fabrics, keeping nutrients: fibers, mineral salts, vitamins.
Freezing from the hygienic point of view is the best method of conservation. Frozen продук* you can be stored within several years. Freezing preserve such foodstuff as meat, fish, melange and so forth the Products which are subject to freezing, should be good-quality, without damage signs.
As cooling understand storage of products at the temperature close to About °s. Cooling is applied to storage of the products containing a considerable quantity of a moisture: fruit, vegetables, milk. The cooled product keeps the initial properties within several days.
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