The question of why milk most often does not sour into curdled milk is difficult to answer unequivocally. There are several reasons why the product does not sour, but simply deteriorates. Neither curd nor whey can be made from rancid milk. The problem needs to be solved comprehensively. Store-bought milk is radically different from what you can taste at your grandmother’s in the village. And the processes occurring in such dairy products vary greatly.
How long should the product sour into yogurt?
It takes a really long time for milk to sour if it is pasteurized.In such a product, not only all harmful bacteria are killed, but also most of the beneficial microorganisms. The processes in this case proceed slowly.
On a note! Pasteurized milk product in an open package can stay in the refrigerator for a week without turning sour. Fermentation processes will gradually take place in it, but they will be beneficial or harmful - it depends on what bacteria accidentally got inside the bag.
Why doesn't homemade milk sour?
Dairy products from the farm do not curdle in heat for the following reasons:
- Poor nutrition of the cow. Overfeeding with protein foods, a lot of acidic foods in the animal’s diet.
- High fat content. In such a product a thick layer of cream is formed, and there is not enough air for fermentation.
- Antibiotics included. If a farmer treats cows with heavy doses of antibiotics, this will certainly affect the taste and properties of raw milk.
- The raw materials are diluted with water. Here the milk mass does not have enough fat content to curdle or sour.
Farm goods are not fermented into yogurt if sanitary standards were violated during its production. For example, the container for it was dirty, or the conditions in which the cows are kept are not optimal.
Methods for solving the problem
If your usual dairy product does not regularly turn sour in the air, you should change the brand of milk. Raw milk purchased from a trusted farmer will definitely form a layer of sour cream when warm.
A special starter will help solve the problem with the product from the store. It is worth knowing that milk marked with ultra-pasteurization does not contain lactic acid bacteria at all.
It is not worth purchasing it for home preparations. Pasteurized milk has every chance of turning into cottage cheese or curdled milk in skillful hands. Some of the beneficial microflora remains there.
Sterilized raw materials are also not suitable for preparing fermented milk products. A crust of bread added to a glass container with milk will help it sour more actively. Even before fermenting, the container for preparation must be rinsed with hot water. The lid of the jar should not be screwed tightly. You can even replace it with clean gauze. Contact with air and heat will help the growth of lactic acid bacteria.
Good milk from a cow can turn sour overnight, but for this to happen, the cow must graze in an alpine meadow, far from roads and industrial zones. In all other cases, milk raw materials are fermented much longer.
