Milk - a valuable product. Its consumption is useful for most of people. Unfortunately, as is fresher, and pasteurized milk quickly spoils. Knowing the answer to a question of why milk turns sour, it is possible to provide its more long-term storage.
The reasons which lead to damage of milk, namely to its souring - a little. The main reason for souring of milk at its storage – bacterial number. It is an indicator of quantity of the microorganisms falling on one cubic centimeter of volume of milk. Today the quantity of bacteria which are a part of milk is given to its damage, considerably above, than twenty years ago. Therefore bactericidal properties of milk because of such large number of fungi and bacteria it is considerably reduced. When the fresh milk arrives on processing enterprises, it passes through pasteurization, and because of this procedure it loses the natural property - ability of protection against souring. Milk contains mold fungi, bacteria and yeast which get to a fresh product from the external environment in the course of milking. Result of non-compliance with rules of storage and hygiene when processing milk on milk plants is increase in bacterial number. What in turn worsens gustatory qualities of dairy product, reduces its nutritional value and also leads to considerable decrease in its periods of storage. At a stage of processing high temperature in milk the lactic bacteria perish, and other butyrate bacteria and their sporous versions, harmful to a human body, safely survive. At observance of terms storage of milk, even at very low temperatures, the bacteria which remained in it and their sporous versions continue to develop. At the same time such bacteria also cause souring of milk. Souring of milk can be also promoted also by its pollution by different contaminants, for example, such as, nitrates, pesticides and antibiotics and also disinfecting and the detergents applied in processing of tanks where dairy products are stored.