Cow's milk, a favorite drink of many children and adults, sometimes tastes bitter. Most of the bitterness is caused by the feed received by the cow; however, the quality and composition of the feed are not the only factors affecting the taste of the drink. Both boiled and raw milk can turn rancid.
The taste of cow's milk depends primarily on what the animal is fed with. The bitter taste and smell of radish can appear in the white drink in the spring, when grazing herds in meadows where a large amount of field mustard, wild radish, and rape grows. Milk is bitter and gets a garlic (onion) smell if the cow has only a few stalks of wild garlic or onions in the fresh grass or in the hay. And if the hay contains dill, caraway seeds, odorous chamomile, fennel, the milk becomes not bitter, but unpleasant when consumed - these pungent plants convey their specific smell and taste to it. When feeding a cow with moldy products (silage, straw, hay), the product of her lactation acquires a musty smell and a bitter taste. The organoleptic properties of milk (taste and smell) change for the worse when the animal is kept in unsanitary conditions: in a dirty, unventilated stall, when the udder cows do not wash before milking. Old milk tastes bitter at the end of lactation (9-10 months), when the cow has already nursed the calf and is ready to start (for a new conception). Bitterness in this case is explained by the breakdown of milk fat already in the udder under the influence of the lipase enzyme, which is excreted intensively during this period. Milk fat, decomposing, forms acids with a bitter taste and unpleasant odor. The process of splitting milk fat can be caused not only by the action of lipase, but also by strong agitation of milk in a can, cistern or other container. Therefore, care must be taken when transporting dairy products over long distances. Sour boiled milk can also turn rancid, unlike unboiled milk (yogurt is obtained from it when souring). This is explained by the fact that two types of bacteria are involved in the souring process: lactic acid and butyric acid. During heat treatment, lactic acid bacteria die, and butyric acid bacteria survive. As a result of their activity, milk becomes sour and becomes bitter. Another cause of milk bitterness is the disease of the cow and its treatment with medications. If the animal received medications, milk from it can be eaten no earlier than 3-4 days after the end of treatment.
