Well, business! Just yesterday, you bought a bottle of homemade milk, put it in the refrigerator, and this evening, wanting to enjoy a warm drink with chocolate cookies, you came across the fact that the purchase has brazenly soured. Why did this happen, what to do about it and how to avoid it in the future?
Why does milk spoil quickly?
Milk contains a certain amount of bacteria. They are classified as normal microflora, and they are the main reason why milk sours. However, here everything is a little more complicated than “just sour”, because bacteria.
Lactic acid fermentation
It is also called “useful”. Its main difference and condition of usefulness is the type of bacteria. Lactic acid fermentation is caused by:
- lactic acid bacteria;
- propionic acid bacteria;
- kefir mushrooms;
- lactic yeast.
It is thanks to them that milk sours normally and from it, then you can naturally make sour cream, kefir, cheese or cottage cheese. Some types of bacteria are specially added to milk to obtain delicious fermented milk products.
Butyric acid and undesirable fermentation
But there is unwanted fermentation, tasteless. It occurs due to butyric acid bacteria, which also cause fermentation, but the milk acquires not a sour, but a bitter taste, the smell is unpleasant. This usually happens with pasteurized and sterilized milk, with cheeses: they tolerate the boiling temperature, and therefore, when lactic acid bacteria die in the process of heat treatment, butyric acids remain and begin their work.
Also, milk can turn sour due to putrefactive bacteria that get into it due to insufficiently good conditions of the contents, as well as due to pollution. They cannot die in the process of pasteurization, and therefore quite often the milk from the package spoils and starts to stink intolerably.
From which the conclusion follows: if the packaged milk is sour, everything is over with it and all that remains is to pour it into the toilet.
How quickly does milk sour?
Homemade milk, unpasteurized and unsterilized, sours at room temperature 12-24 hours after it has been milked. But it happens that homemade milk does not sour. This is due to the fact that the cow has developed ketosis. Such milk is very harmful, it almost does not ferment, and the cream has a very pronounced bitter taste.
How to prolong the life of milk?
If you don’t want to drink all the milk at once, but you want to enjoy it a little more, try these excellent methods.
The cold way
Putting milk in the refrigerator is, of course, not bad, but you can also pour milk into clean plastic bottles of 0.5 liters, and then put it in the freezer. Frozen milk will last much longer than just sitting in the fridge. Before starting, you can boil it if you plan to store it longer.
You can also make small portions of milk for drinks. To do this, arm yourself with an ice cube tray, pour milk into the cells and put it in the freezer. When it freezes, put the milk lollipops in a bag, and then put them back in the freezer. You can add it to tea and coffee in the morning, it will be delicious in the summer – just the same.
But it is important to know! Re-freezing milk is unacceptable, otherwise it will spoil!
Frozen milk can be stored for up to 6 months.
The hot way
The best way to extend the life of homemade milk is to boil it. This is a simple and quick method called pasteurization. Pasteurized milk will be stored for 3 to 7 days in the refrigerator. But it is important not to expose it to direct sunlight and not to forget it on the table.
Another great way to boil milk and prevent it from curdling is to add a tablespoon of sugar for every liter. So it will be stored for a long time and will not curdle when boiling.
However, you cannot make yogurt from boiled milk.
Do you have your own methods? Tell us about it in the comments!
The opinion of the editors may not coincide with the opinion of the author of the article.