What is the purpose of cream of tartar in whipping egg whites?

• A. Stabilizes the foam and increases volume; also helps with preventing sugar crystallization in meringues.
• B. Increases sweetness.
• C. Inhibits fermentation.
• D. Acts as a leavener.

Answer: (A)

Cream of tartar provides acidity that strengthens the egg white foam. Lowering the pH helps the proteins unfold and form a stable network around air bubbles, so the foam traps more air, grows in volume, and stays stable as it whips and bakes. It also helps prevent sugar from crystallizing too much, giving meringues a smoother texture. It isn’t added for sweetness, nor is it a fermentation inhibitor or a stand-alone leavener—the stabilizing, volume-boosting effect on the foam is what makes it useful in whipping egg whites.