Cream of tartar is one of those ingredients you might have seen in your grandma’s pantry without knowing what it’s used for. After all, its name doesn’t give you a clue—not like baking powder or baking soda. Yet just a touch of it makes a big difference in your baking.
What is cream of tartar?
First of all, it’s not creamy. It’s a dry, powdery, acidic byproduct of fermenting grapes into wine. Its science name is potassium bitartrate, potassium hydrogen tartrate or tartaric acid. But you can find it in the spice aisle labeled as cream of tartar.
What is cream of tartar used for?
Adding a small amount of cream of tartar when you’re beating egg whites—usually 1/8 teaspoon per egg white—speeds up the creation of foam and helps stabilize the structure of those air bubbles you’re whipping up. In baking, this means mile-high meringue pies.