Cream of tartar is an all-natural ingredient essential to holiday baking. It adds texture, volume and lift to beaten egg whites in angel food cake, meringue shells, meringue for pies and 7-minute frostings, resulting in light and fluffy holiday desserts. Cream of tartar, also known as tartaric acid, is a byproduct left after the fermentation of grapes into wine. This tasteless baking necessity stabilizes beaten egg whites in desserts and egg dishes. A pinch of cream of tartar also helps prevent homemade whipped cream from deflating. To make your own baking powder, simply mix 1/2 tsp.