McCormick Gourmet Collection Cream of Tartar is a derivative of tartaric acid, a natural byproduct of winemaking. It's used to stabilize beaten egg whites when preparing angel food cake, meringues, macarons, and frostings, resulting in light and fluffy desserts. A pinch of cream of tartar helps to stabilize homemade whipped cream, too. Cream of tartar also stops sugar syrup from crystallizing — so you can achieve soft, chewy snickerdoodles.