What is cream of tartar?
Cream of tartar is the dry, powdery version of tartaric acid. This acid occurs organically in many fruits, grapes in particular. In fact, cream of tartar is the byproduct of fermented grapes from winemaking.
What does it do?
You may not use cream of tartar often in your recipes, but it is imperative for the likes of meringues, soufflés and some cakes because it stabilizes the proteins in whipped egg whites to ensure meringues are voluminous and that cakes are light and airy.
How to replace it and why it works?
A suitable replacement to try is 1 tsp of vinegar or lemon juice for every ½ tsp of cream of tartar. This works because cream of tartar is acidic, just like vinegar and lemon. These substitutes function particularly well when whipping egg whites for a meringue.
Looking for ways to substitute other ingredients in the kitchen? Read these articles.