Why is milk sour?
People have long noticed that in a thunderstorm milk becomes sour, but that's why milk sours milk faster in bad weather, scientists do not yet know. It is believed that electromagnetic waves affect the fermentation process, but this has not been proven.
The process of fermentation or layering of milk is familiar to everyone since childhood. But many people mistakenly believe that the milk turns sour from the heat. It is not, or rather not quite. The fermentation process is accelerated from the heat, but even in the fridge the milk will sour sooner or later.
Causes of milk souring
It's all about streptococci, which are very numerous in milk. They react with milk sugar, which provokes the release of lactic acid. Since such bacteria resemble a bacillus in shape, they are called “milk” or “Bulgarian” bacilli. Bulgarian - because they were first investigated by Ivan Mechnikov, who studied Bulgarian fermented milk products and their effects on the body.
He was not the only one who wondered why sour milk.The French chemist Louis Pasteur, back in 1857, proved in his research that fermentation is caused by the bacteria that are present in the product. His early studies are related to wine (this is not surprising, because France is a world wine producer). Pasteur proved that yeast microorganisms are the main reason why wine turns into vinegar. A good way to prolong the freshness of products is to heat them up to a temperature of 50-60 degrees and hold them for a while. Today, this method is mainly used for juices, milk and beer, and we call it "pasteurization".
Dairy products are very good for the body, but there is one condition - it should be sour milk in "natural" conditions, that is, at room temperature. But sour milk from the refrigerator is harmful to the body and can cause poisoning.