Skim Milk Casein and Caseinates

Skim milk is the byproduct of the cream, butter and ghee industry. It is rich in solidsnot- fat content and has high nutritional value. In dairy plants it is mostly utilized either in standardization for the manufacture of the main dairy products or preserved by removing moisture in spray dried form to obtain skim milk powder. The skim milk when utilized in either of these two forms or consumed, as a liquid is not considered as a byproduct. It is regarded as a byproduct only when it is either not economically utilized or utilized for derived byproducts like casein and related products,coprecipitates, protein hydrolysates, etc.

Casein is the major protein in milk and constitutes about 80% of the total protein content and about 20%, is the whey or serum proteins. Commercial-casein is made from skim milk by one of the two general methods – precipitation by acid to make acid casein or coagulation with rennet to make rennet casein. In addition to these two main types there are other commercially available casein products of importance,viz.: (1) Coprecipitate, made by heating skim milk to a high temperature and then precipitating the casein/whey protein complex, usually with calcium chloride. The coprecipitate also contains whey proteins and calcium and (2) Caseinates, commonly sodium caseinate which is obtained from acid casein dissolved in sodium hydroxide