Whey is a by-product of cheese production; it is one of the components which separates from milk after curdling, when rennet or an edible acidic substance is added. Remember the children's poem about Little Miss Muffet "eating her curds and whey"? That's what she had - a bowl of curdled milk. Today, with some processing, we know this product as "cottage cheese".
Milk is collected from dairy cows and taken to the dairy company for processing. The milk can be sold as milk or used to make cheese. The milk is pasteurised and a bacteriological starter is added to 'sour' and thicken the milk. A renneting agent is added to form curds. The curd is left to set. When the curds are cut, the whey is released. The curds are either 'cooked' or piled on top of each other to further expel the whey.This whey was considered a waste product and fed to pigs. Nowdays, this whey or sweet dairy whey is the raw material used to make protein powders. The sweet dairy whey is passed through ultra-fine filters. As it passes through, the filters remove fat and lactose and leave behind concentrated whey protein in a liquid form. The liquid is then dried.