Spice Island Cream of Tartar 3 oz jar is a single ingredient thatâs created as grape juice turns to wine. It is one of the main ingredients in baking powder and is used to stabilize beaten egg whites. Add 1/8 tsp. per egg white when making souffles, meringues, angel food, chiffon cakes, and candy. Tartaric acid, or cream of tartar, is the natural by-product of fermented grapes, collected from the wall of the casks used to age fine wines. Naturally reddish-brown in color, itâs carefully refined...