temperature Action on fibers
Heat Action (60 °s and above) causes coagulation of fibers in cytoplasm of cages of microorganisms. As this process is irreversible, as a result the microorganism becomes impractical. Vegetative forms of microorganisms instantly react to a heat. Are steadier against a heat sporoobrazujushchie microorganisms as water in their cages is in the connected condition and there is no coagulation of fibers. However viability dispute under the influence of a heat decreases.
The Most widespread methods of conservation with heat use are sterilisation and pasteurisation.
At sterilisation of foodstuff hermetically corked product (meat, fish, vegetables) heats up in an autoclave at temperature 112-120°С. Enzymes Thus collapse, and microorganisms and their disputes perish.
Pasteurization of products (juice, marinades, wines) spend at temperature 63-85 °s therefore vegetative forms of microorganisms are destroyed. Pasteurisation when a product heat up at temperature 63-65 °s during 30 mines, and short-term, or high, pasteurisation is applied long, or low. Thus a product heat up to 80 With With and above within several minutes. Instant pasteurisation can be applied at the same temperature, but within several seconds.
A sterilisation Version is the method offered in GDR uperizatsii, applied to milk conservation at its heating to 150°С during 3 D with then milk cool. At such processing many vitamins remain.
Dehydration of products, or drying, is based that from a product the moisture leaves. Removal of a moisture to 8 15% promotes suppression of ability to live and reproduction of microorganisms. The metabolism between a cage of a microorganism and foodstuff - sources of nutrients thus stops. Dehydration is applied to conservation of milk and dairy products (dried milk, cream), vegetables, fruit, fish and half-finished products (soups and porridges-concentrates).
Sublimation combines in itself freezing and dehydration. It is a special method of drying of the frozen product in vacuum. In sublimatore the vacuum to 0,67 kpa (5 mm hg) is created. In the beginning a product freeze to-18 (-20) °s, and then heat up till 30-40 °s. Thus ice passes in steam, passing a liquid condition. After sublimatsionnoj drying in a product 5% of a moisture contain. Products sublimatsionnoj drying have wide application in a diet of cosmonauts.
Action of the raised osmotic pressure. This method consists in conservation of products by chloride of sodium or the sugar promoting bakteriostatiches effect. At addition to foodstuff of 10 15% of chloride of sodium round cages of microorganisms the hypertensive environment is created. In usual conditions of a cage of microorganisms are in a hypertensive condition in relation to a product that causes receipt ditatelnyh substances from a product in cages. At a pickles of a product at the expense of the raised osmotic pressure round cages there is a cytoplasm dehydration, a food and reproduction of microorganisms stops. But microorganisms thus do not perish. Conservation by chloride of sodium from the hygienic point of view is considered the most ineffective method as thus in a brine valuable nutrients leave: fibers, mineral elements, vitamins.
At action of solutions of sugar of the big concentration (60-65%) high osmotic pressure also is created.
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