The souring of milk is a complex microbiological process. For lactic acid bacteria (trampeling, acidophilic, mesophilic and bifidobacteria) milk is an ideal medium. Therefore, in fresh milk at room temperature, bacteria begin to actively proliferate, digesting lactose into lactic acid. As a result, the milk goes sour.
Sometimes when boiling milk it curdled. This is due to the fact that lactic acid bacteria have time to work on glory and turned into lactic acid the lactose.
Perhaps the best way to keep fresh natural milk from souring is its pasteurization or sterilization. During pasteurization (heating to 63 — 750) most of the heat-sensitive lactic acid bacteria are killed, but remain more stable, so pasteurized milk may be stored in the fridge without losing its properties within 2-3 days.
If the milk to boil (sterilize), as a result of this heat treatment will die not only lactic acid bacteria and their spores, therefore, this milk preserves properties during the week.
If before boiling milk, dissolve in it the sugar, adding it 1 tablespoon per liter of milk, such milk will not curdle when boiled, and will be kept much longer.
Boiled milk should not be stored in bright light, especially direct sunlight, because the milk fat starts to turn yellow, and the milk loses vitamins B2 and C.
It is thanks to heat treatment not sour pasteurized or sterilized milk. Even if you leave an open bag of milk on the window, framing him as the sun's rays, instead of souring and curdling will occur peptonization. Instead of curdled milk in the package forms a white liquid, has a bitter taste and are unfit for food.
To prevent the souring of milk during the heat, enough to put in a jug of milk 3-4 normal piece of shit.
As a result, the milk will not sour and will keep their freshness for several days.
Glass jar with milk should be placed in a wide pot with cold water. The lid off the can be removed, and instead, cover the jar with a clean towel so that the edges were submerged in water in a saucepan.
Thanks to the water evaporated from the pan and the surface of the towel, the milk does not overheat and does not spoil even in hot summer day.
Our ancestors to ensure that the milk is not sour, threw it at the frog. Bactericidal substances secreted by her skin, suspended the process of converting milk protein in the acid and the milk was kept long enough.
Some contemporaries, selling milk in the markets, with the aim of slowing down the process of turning sour add antibiotics, soda, and even ammonia. Therefore, when buying in the market approach to the selection of milk responsibly and seriously.
Let the natural milk will always be fresh and rewarding! Bon appétit!