Casein is a family of related phosphoproteins (αS1, αS2, β, κ). They are found in mammalian milk comprising about 80% of the proteins in cow’s milk and between 20% and 60% of the proteins in human milk. Caseins play an important in role in stabilizing food structures such as emulsions as well as in dairy-based products as cheese, yoghurt, infant formula and medical food.

Furthermore, casein is used for powders requiring rapid dispersion into water, ranging from coffee creamers to instant cream soups. Another application of casein is the use in protein supplements, as casein molecules form a cloth in the stomach which provides a sustained slow release of amino acids in the blood stream.