Cream of Tartar
Cream of tartar is is the common name for potassium hydrogen tartrate, an acid salt that has a number of uses in cooking. Now, before you get all jittery about the thought of cooking with an acid, it’s worth noting that milk, brown sugar, steak, plums, and just about every other food we eat is acidic. In fact, egg whites, baking soda, and milk are the only non-acidic (alkaline) foods we have.
Cream of tartar is obtained when tartaric acid is half neutralized with potassium hydroxide, transforming it into a salt. Grapes are the only significant natural source of tartaric acid, and cream of tartar is a obtained from sediment produced in the process of making wine. (The journal Nature reported some years ago that traces of calcium tartrate found in a pottery jar in the ruins of a village in northern Iran are evidence that wine was being made more than 7,000 years ago.)
Cream of tartar is best known in our kitchens for helping stabilize and give more volume to beaten egg whites. It is the acidic ingredient in some brands of baking powder. It is also used to produce a creamier texture in sugary desserts such as candy and frosting. It is used commercially in some soft drinks, candies, bakery products, gelatin desserts, and photography products. Cream of tartar can also be used to clean brass and copper cookware