Why does vinegar curdle milk?

Question

Why does adding vinegar cause the protein in milk to curdle? Please explain in detail.

Answer 1

Vinegar is a dilute acetic acid.
ACID CURDLING
In normal conditions milk has a ph of about 6.5-6.7 and at this ph value the casein is without protons, it has a negative charge and therefore the casein micelles are relatively soluble, because they repel each others. In an acid ambient milk coagulates, because casein has its isoelectric point at 4.6 ph, that is at this ph value it has a quantity of positive charges equal to the quantity of negative charges and the positive part of each "micelle" is attracted by the negative part of the others, causing the formation of ionic bonds among the "micelle" working against the dipole-dipole bonds with water, so that the protein precipitates in the form of demineralized casein and in the solution remain soluble calcium salts.
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Answer 2

Vinegar In Milk

Answer 3

Vinegar is an acid. Acids cause proteins in milk to breakdown and curdle. This is the first stage of digestion.

By the way, it is not true that a baby vomits because the milk soured in its stomach. Again, that is the normal start of digestion.

Cottage cheese and spoiled milk curdle because of acids from bacteria.

Answer 4

Curd is a dairy product obtained by curdling (coagulating) milk with rennet or an edible acidic substance such as lemon juice or vinegar and then draining off the liquid portion (called whey). Milk that has been left to sour (raw milk alone or pasteurized milk with added lactic acid bacteria) will also naturally produce curds, and sour milk cheese is produced this way. The increased acidity causes the milk proteins (casein) to tangle into solid masses, or "curds". The rest, which contains only whey proteins, is the whey. In cow's milk, 80% of the proteins are caseins. Curd products vary by region and include cottage cheese, quark (both curdled by bacteria and sometimes also rennet) and paneer (curdled with lemon juice). The word can also refer to a non-dairy substance of similar appearance or consistency, though in these cases a modifier or the word curdled is generally used (e.g. bean curd, lemon curd, or curdled eggs).

Answer 5

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RE:
Why does vinegar curdle milk?
Why does adding vinegar cause the protein in milk to curdle? Please explain in detail.

Answer 6

Vinegar is an acetic acid solution. The acid lowers the pH of the milk to the isoelectric points of the milk proteins. Proteins exhibit their minimum solubility at the isoelectric point and, as a result, the precipitate forming soft curds. If the curds are heated they before firm (losing more of the trapped fluid). Casein is the main protein that precipitates.

Answer 7

Not an expert here, but it might be related to some alcohol in the vinegar intreracting with the bacteria in the milk. The milk curds when it gets old, and today's milk is usually pasteurised, plus put in a freezer to prevent the growth of bacteria from happening. So vinegar with its sweetness and its acid is probably a perfect fuel for bacteria, and it warms them up like alcohol warms the thorat of a drunkard when ingested. The vinegar would then simply quicken the curdling of milk.