Whey protein is a mixture of proteins, consisting of α-lactalbumin, β-lactoglobulin, serum albumin, immunoglobulins and various other proteins. Whey protein can be obtained from milk by acid precipitation of the caseins, by making cheese or by membrane filtration.
Whey protein is commonly marketed as a dietary supplement, for muscle growth and development. It is sold as a powder, so it can be mixed with water or other liquids. Whey protein is also quite commonly used as a thickener to improve texture and decrease syneresis in many types of yogurts and other products. In infant formula and many types of medical food products it is an essential ingredient.