The liquid byproduct of producing cheese. Because whey contains significant proteins, lactose and minerals, it is increasingly being used as an ingredient in producing other foods. Whey is often used to make Ricotta.

The California Milk Advisory Board

When milk is renneted and sets, it becomes curds, the solids; and whey becomes the liquid. This liquid contains a percentage of the albuminous proteins that were in the milk from the start but which the rennet didn't capture in the curd. The method of capturing this leftover protein is with high heat and an acid, like vinegar. The protein coagulates at about 175F with the addition of acid (vinegar or other), into a very light mass creating the great fresh cheese, ricotta.