An indispensable ingredient in baking, cream of tartar when combined with baking soda and water acts as a leavening agent in cakes, quick breads and souffles. To aid in stiffening egg whites, add a pinch when beating. Cream of tartar powder is widely distributed by nature in many fruits, but is usually obtained as a natural, pure ingredient left behind after grape juice has fermented to wine. During the fermentation of the grapes, tartar crystallizes in the wine casks. The crystals are collected and purified to produce the white, odorless, acidic powder used for culinary and other household purposes. Cream of Tartar is. Cool and store in a plastic bag until ready to use. Use 1/8 teaspoon per egg white to make souffles, meringues, angel food, chiffon cakes, and candy.