Casein, a milk protein and as the colour suggests, is found only in milk. Milk is white only because of Casein present in it, which emits in the form of collidal suspension. Casein is obtained commercially from milk by precipitation under acidic conditions followed by filtration, washing and drying. It is an integral constituent of milk which helps in building immunity. It is highly nutritious, having all the essential amino acids and is widely used in different food preparations. Beside edible use, it also has various industrial applications.