What Is Cream of Tartar or Potassium Bitartrate?

Cream of tartar is used in both baking and cleaning
Cream of tartar is used in both baking and cleaning. skhoward / Getty Images

Cream of tartar or potassium bitartrate is a common household chemical and cooking ingredient. Here's a look at what cream of tartar is, where it comes from, and how the cream of tartar is used.

Basic Cream of Tartar Facts

Cream of Tartar is potassium bitartrate, also known as potassium hydrogen tartrate, which has a chemical formula of KC4H5O6. Cream of tartar is an odorless white crystalline powder.

Where Does Cream of Tartar Come From?

Cream of tartar or potassium bitartrate crystallizes out of solution when grapes are fermented during winemaking. Crystals of cream of tartar may precipitate out of grape juice after it has been chilled or left to stand or the crystals may be found on the corks of wine bottles where the wine has been stored under cool conditions. The crude crystals, called beeswing, may be collected by filtering the grape juice or wine through cheesecloth.

Cream of Tartar Uses

Cream of tartar is used primarily in cooking, though it is also used as a cleaning agent by mixing it together with white vinegar and rubbing the paste onto hard water deposits and soap scum. Here are some of the culinary uses of cream of tartar:

  • Added to whipped cream after it has been whipped to stabilize it.
  • Added to egg whites when whipping them to increase their volume and help them maintain peaks at higher temperatures.
  • Added when boiling vegetables to reduce discoloration.
  • One of the key ingredients in some formulations of baking powder, where it reacts with baking soda and an acid to produce carbon dioxide to promote rising of baked goods.
  • Found with potassium chloride in sodium-free salt substitutes.
  • Used to make icing for gingerbread houses and for other frosting, where it acts to prevent sugar from re-bonding and crystallizing.
  • Used to clean brass and copper cookware and fixtures.
  • Added to soft drinks, gelatin, photography chemicals, baked goods, and many other products.

Shelf Life and Cream of Tartar Substitution

As long as it is kept in a sealed container away from heat and direct light, cream of tartar maintains its effectiveness indefinitely.

If cream of tartar is used in a cookie recipe, it's used with baking soda to form a type of double-acting baking powder. For this type of recipe, omit both the cream of tartar and the baking soda and use baking powder instead. The substitution is to use 1 teaspoon of baking powder for each 5/8 teaspoons cream of tartar and 1/4 teaspoon baking soda. After you do the math for your recipe, you may find it calls for additional baking soda. If this is the case, you can add the extra baking soda to the batter.

While it's best to use cream of tartar if it's called for in a recipe, if you must substitute, you can add vinegar or lemon juice instead. In baking recipes, it takes a bit more of the liquid ingredient to get the same acidity, so add 1 teaspoon of vinegar or lemon juice for every 1/2 teaspoon of cream of tartar. The flavor will be affected (not necessarily in a bad way), but the biggest potential problem is there will be more liquid in the recipe.

For whipping egg whites, you can use 1/2 teaspoon lemon juice per egg white.