Potassium bitartrate (poe-TAS-ee-yum bye-TAR-trate) is a colorless crystalline or white powdery solid with a pleasant, slightly acidic taste. The compound is a by-product of the fermentation of grape juice and, as such, may have been known to humans for as long as seven thousand years. An article in the journal Nature reported some years ago that traces of the calcium salt of tartaric acid, a cousin of potassium bitartrate, was found in remnants of a pottery jar in northern Iran dating to about 7,000 bce. Potassium bitartrate was used by ancient people in a wide range of household uses, from cooking and baking to cleaning. The true chemical nature of the substance long known as cream of tartar was determined in 1770 by the Swedish chemist Karl Wilhelm Scheele (1742–1786).
Potassium hydrogen tartrate; potassium acid tartrate; cream of tartar
Potassium, hydrogen, carbon, oxygen
Salt (acid salt); inorganic
Somewhat soluble in cold water; very soluble in hot water; insoluble in alcohol
HOW IT IS MADE
Potassium bitartrate is made today by the process that has been used for centuries. Wine lees (the solid material left after grapes have been crushed to make wine) are treated with hot water, which dissolves the potassium bitartrate. The hot solution is then allowed to evaporate. As potassium bitartrate crystals form, they are removed and purified.
COMMON USES AND POTENTIAL HAZARDS
The primary use of potassium bitartrate is in commercial food production and household cooking and baking. The compound is added to foods to stabilize egg whites after they have been beaten, to add body to a product, and to produce creamier textures for sugar-based foods. A small amount of potassium bitartrate also adds a pleasantly acidic taste to foods. The compound is found most commonly in baked goods, candies, crackers, confections, gelatins, puddings, jams and jellies, soft drinks, margarines, and frostings. Some of the functions that potassium bitartrate performs in foods include:
- It acts as a leavening agent, causing a product to rise, in baked goods;
- It serves as an anticaking agent and stabilizer to thicken some food products;
- It prevents the crystallization of sugars when making candy and sugary syrups;
- It hides the harsh aftertaste and intensifies the flavors of some foods; and
- It improves the color of vegetables that have been boiled during preparation.
Potassium bitartrate also has a number of other uses. It can be used as a laxative for both humans and domestic animals. It is used in the processing of some metals, giving a colored tinge to the final product. The compound is also an ingredient in products used to clean brass, copper, aluminum, and other metals. And it is used in the chemical industry as a raw material for the preparation of other tartrate compounds.
There are no known health hazards for potassium bitartrate except for the general overall caution given in the Introduction that all chemicals in some concentrations can pose a hazard. Potassium bitartrate is thought to be one of the safest chemical compounds for general use.
FOR FURTHER INFORMATION
"Potassium Bitartrate." ChemicalLand21.com. http://www.chemicalland21.com/arokorhi/lifescience/foco/POTASSIUM%20BITARTRATE.htm (accessed on October 29, 2005).
"Potassium Bitartrate." J. T. Baker. http://www.jtbaker.com/msds/englishhtml/p5565.htm (accessed on October 29, 2005).