Q: Older baking recipes use cream of tartar. What is it and is there any substitute when using vintage recipes?
-- Meredith Booth, Wallkill, New York
A: No need to look for a substitute for cream of tartar, it is readily available for purchase in any grocery store. Look for it in the aisle where spices and other baking ingredients are sold.
Cream of tartar still is used widely in baking. You rarely find a recipe for snickerdoodle cookies that doesn't call for it. Cream of tartar acts as a stabilizer and adds volume to egg whites when beating them for meringue. It is often used in candy making because it prevents sugars from crystallizing and gives candy and other sugary confections such as frosting a creamier texture.
Cream of tartar is actually potassium bitartrate or potassium hydrogen tartrate, an acid salt derived from tartaric acid, which is a byproduct of winemaking. When wine is fermenting, the tartaric acid forms on the inside of wine caskets, leaving behind a white sediment that is removed and ground into a fine powder.
It is the acid ingredient in baking powder, along with baking soda and cornstarch, which is why baking powder, unlike baking soda, doesn't have to have another acid in its recipe to get it working as a leavener. It provides the acid kick needed in batters to get quick breads and cookies to rise.
Because it is an acid, should you need to find a substitute for it, look to other acids, such as white vinegar.
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