Cream of tartar, technically known as potassium hydrogen tartrate, is primarily used in cooking and other household tasks. This acid is one of the main ingredients in baking powder, and aids in stabilizing eggs when making a meringue. The uses for cream of tartar also include making candy or cooked frostings, as it helps to encourage sugar to melt rather than crystalize when heated. Around the home, uses for cream of tartar include cleaning brass and copper, as well as porcelain and a variety of fabrics.
Baking powder, a leavening agent used to help baked goods such as cookies and cakes rise, is often made from a mix of baking powder and cream of tartar. The acidic properties of the tartar help to activate the leavening properties of the baking powder, helping to create air pockets inside dough. When baking powder is not available, straight baking soda can be mixed with cream of tartar at a rate of one tablespoon of baking soda to half a teaspoon of tartar. This is one of the primary uses for cream of tartar.
Other common uses for cream of tartar are helping to stabilize other ingredients when cooking, allowing them to increase in volume without breaking down. This is most common in making meringue, a popular topping for pie or a light dessert on its own. Cream of tartar is added to egg whites, typically 1/8 of a teaspoon per egg, before the whites are beaten, enabling them to increase dramatically in volume as air is whisked in. The resulting product can be baked, folded into other ingredients, or used to top a variety of pies and cakes.
Another of the most common uses for cream of tartar is in making candy and frosting. Sugar, when exposed to heat, tends to form tiny crystals. While this is desirable when making hard candy, it can add a grainy texture to chewy varieties. The acidic properties of tartar prevent the sugar from crystalizing, allowing it to melt completely into the other ingredients, resulting in a silky smooth texture. Frostings that require cooking, such as coconut pecan and several white and chocolate recipes, also often call for cream of tartar, as it helps the sugar incorporate fully into the other ingredients. Cooked frosting made without tartar can often turn out grainy or even lumpy.
Outside of cooking, cleaning brass and copper are common uses for cream of tartar. When mixed with lemon juice can help to remove discoloration and spots from any number of items made from these materials. On its own, this product can also remove stains from porcelain, and, when mixed with glycerin, it is a highly effective stain remover for fabric.