What is Cream of Tartar? Cream of Tartar is a natural leavening agent, used in cooking and baking as a substitute for chemical yeast, which is widely used for the increased fluffiness and lightness it gives to food. rnIt is excellent for people who are intolerant to yeast. But its uses are not limited to this, cream of tartar helps increase the volume and stability of stiffly beaten egg whites in meringues and soufflés, it can help vegetables retain their colour and prevent syrups from crystallising, and finally you can use it to make modelling dough for children!