Cream of Tartar

Cream of tartar is a fine white powder made from the crystals that are deposited in wine barrels. The crystals are purified and ground to form cream of tartar, which is used to stabilise the egg whites beaten into cakes such as sponge and angel food cakes, and to stop the sugar in candy from crystallising. Cream of tartar is the acidic ingredient in baking powder, which activates the bicarbonate of soda.