Acid casein

Casein protein precipitated from skim milk by acidifying to its isoelectric point around pH 4.6, then washed and dried into a powder. Acidification may use direct acid addition or lactic cultures. Unlike rennet casein it dissolves readily in alkali, which made it historically prized for adhesives, paper coatings and paints; food uses include coffee whiteners, nutrition bars and processed cheese analogues. Its manufacture is a major outlet for surplus skim milk in dairy regions, converting a perishable liquid into a stable, shippable protein ingredient with both food and industrial markets.