Buttermilk

Buttermilk is the tangy flavoured residue remaining after separation of butter grains during buttermaking. It is low in fat but rich in phospholipids and proteins, resulting from breakdown of the milk fat globule membranes during churning of cream, which releases membrane material into the liquid. Buttermilk remaining after manufacture of sweet cream butter differs slightly in composition from that resulting from cultured cream buttermaking, being less acidic. A commercial product called cultured buttermilk is made by adding lactic cultures to milk, giving a thicker, tangier drink widely used in baking for its tenderizing acidity.