Soufflé has a reputation for being difficult and prone to collapsing. Its signature height is created by beaten egg whites, which firm up in the oven's heat, trapping air bubbles in the finished soufflé. Cream of tartar coagulates the protein in the egg whites, strengthening them. This helps prevent the dreaded collapse when you remove the soufflé from the oven. If you do not have cream of tartar on hand, substitute another acidic ingredient.
What Cream of Tartar Is
Cream of tartar is a white, powdery substance derived from tartaric acid during the winemaking process. It has several culinary uses. The most common is as a key component in baking powder, where it reacts with baking soda to produce carbon dioxide in chemically leavened baked goods.
How Cream of Tartar Works
Cream of tartar is an acid. When the proteins in egg whites come into contact with an acid, they coagulate. This is useful in a soufflé because the coagulated egg proteins are more tightly woven together than noncoagulated proteins. They are less likely to fall apart, letting air escape. Just 1/4 teaspoon of cream of tartar is sufficient to coagulate six egg whites.
If you do not have cream of tartar in your pantry, your soufflé will not be ruined. You can make soufflé without adding any acid to your egg whites, as long as you beat them to very stiff peaks. You can also substitute another acid. If you happen to have tartaric or citric acid, you can use either instead of cream of tartar. Alternatively, use lemon juice or vinegar in an equal amount: If your recipe calls for 1/4 teaspoon of cream of tartar, use 1/4 teaspoon of lemon juice or vinegar.
Don't Overdo It
Soufflé gets its rise from the air trapped by coagulated egg proteins. Don't be tempted to add extra acid to the egg whites to get even more lift. Your soufflé will pick up a sour flavor from the acid, and that extra lift may actually cause your soufflé to fall. As the air bubbles rise, the overcoagulated proteins will break instead of stretch, letting the air escape. Follow your recipe and substitute carefully if necessary to ensure a delicious soufflé.