*2.3.1.3 Casein*

Casein is a milk protein. It has coil-like structure [36] due to its structure, it can be processed easily. Casein is dissolved in water, but after being dipped in water, it gains about 50% weight [37]. By treating the aqueous solution of casein molecule, it forms films, which are flexible, tasteless and transparent [31, 33]. Casein film helps to retard migration of aroma, CO2 and O2, because casein contains more number of polar groups which have excellent adhering property [38]. By treating the casein film with buffer at its isoelectric point may enhance the mechanical property and reduce solubility of casein film [39]. Its drawback is its high price.
