Fresh whole milk is skimmed and pasteurized before undergoing an acidification at pH 4.6 (isoelectric point of casein). Then the caseins aggregate to form an acid coagulum of casein, commonly called curd. It is separated by a centrifugation of the whey and then washed to obtain a casein containing less than 1% fat, less than 1% minerals and about 0.1% lactose. This curd, insoluble in water, is then ground and dried in dryer. Then the acid casein is obtained.