With fall of temperature biochemical and microbiological processes are slowed down. At temperatures below 0 of 0C water in fruit and vegetables freezes that very much reminds drying of the environment. The preserving action everywhere, however, the temporary. In cold some processes of decomposition are only slowed down.
Conservation as any reasonable intervention which is applied to raw materials when warehousing, does not destroy its natural properties. Thus it is necessary to pay attention and to other immediate tasks, such as, for example, preservation of a nutrition value, preservation of the major organoleptic properties - a look, a smell, taste and a consistence - and the greatest restrictions of losses of the major compound substances, first of all, of vitamins. Such effect can achieve in the different ways. Every way conservations has the merits and demerits, some have the specific features, others demand an obligatory set of products. For requirements of house conservation we will sort only those ways which can be realized from the point of view of the available preserving equipment.
Action of acetic bacteria leads to transformation of ethanol into acetic acid (CH3COOH). This circumstance is used by production of vinegar. About 10% ethanol solution with 1 - 2% acetic acid at continuous intensive blowing off by air at a temperature of 30 of 0C sbrazhivatsya in vinegar. The exit makes 90%.
For good passing of lactic fermentation it is required to follow some rules. Well peeled vegetables in the whole look (for example, cucumbers) or in cut (shredded stack in pure ware. Vegetables in ware well press that there was an air, thus cellular juice is released. If it is not enough juice, it is possible to add 1,5% solution of table salt. All surface is filled in with a brine (the content of salt of 1,7-2% for all volume of ware). Contents are required to be put so that everything constantly was lower than a level of a brine. The filled capacities under the influence of surrounding temperature in some days will be fermented under the influence of microflora which under normal conditions is present on vegetables. If vegetables before ferment subjected to thermal treatment (scalding, it is necessary to add lactic ferment. It is best of all to use pure culture of ferment according to the instruction of the manufacturer. If necessary it is possible will add also sour serum. Anyway ferment in fresh juice has to be applied. At a fermentation delete from a ware surface, as required, the arising mold and if necessary add a brine (1,5% of table salt) so that vegetables were constantly flooded. It eliminates access of air to contents and undesirable transition of lactic fermentation on oil, a softening of fruits and the subsequent putrefactive decomposition.
Action of lactic bacteria leads to transformation of some saccharites into lactic acid or into some other, less desirable substances (mainly, acids: acetic, oil, ethanol, CO. This way is classical at preservation of vegetables. Usually sour fruit does not subject to lactic or spirit fermentation because they contain a little sugary and the albumens necessary for fermentation.
Cooling it is possible to prolong storage of fruit and vegetables only for a short time. In practice it is used only at long warehousing of raw materials before processing. Temperatures of warehousing have to be minimum the most close located over a freezing point. From the point of view of suppression of all biochemical reactions, it is favorable to store at low temperatures and ready-made products. Better their natural and organoleptic properties remain.
Recently there was a tendency to reduce the content of sugar in products as undesirable power source. Therefore it is necessary to apply other ways of conservation, most often pasteurization or chemical conservation at low concentration of sugar.