Casein from bovine milk is a phosphoprotein. It make up approximately 80% of the total protein in bovine milk. It is proposed to be the main protective constituent in milk.

It has a wide variety of uses, from being a major component of cheese, to use as a food additive, to a binder for safety matches. As a food source, casein supplies amino acids; carbohydrates; and two inorganic elements, calcium and phosphorus.

It is produced by controlled acidification of pure, pasteurized skim milk, resulting in precipitation of casein curd. The curd is then washed, dried, and ground to a consistent particle size.