80 % of milk protein consists of caseins. They are the most concentrated form of milk protein, when dried to powder during the manufacturing process. Caseins are insoluble in water. They are generally defined according to the Precipitation Process.

Acid Casein: Precipitation by acidification of the milk at the isoelectric point pH 4.6.

Rennet Casein: Precipitation with use of microbial rennet at neutral pH-level.