Chances are you have eaten a lot of potassium sorbate in your life. Potassium sorbate inhibits the formation of mold, yeast and fungi in food products ranging from cheese to wine to baked goods. It is also used as a preservative in cosmetics and pharmaceutical products to increase shelf-life. Potassium sorbate is five to 10 times more effective at preserving foods than sodium benzoate, another popular preservative. While usually synthetically made, it does occur naturally in some fruits.
Chemistry
Potassium sorbate is the potassium salt of sorbic acid. Sorbic acid, known chemically as 2,4-Hexadienoic acid has the molecular formula of C6H7KO2. This means one molecule has six carbon atoms, seven hydrogen atoms, one potassium atom, and two oxygen atoms. It has a molecular weight of 150.21688 g per mole.
Physical Properties
Purified potassium sorbate appears as a white to slightly yellow crystalline powder and is water soluble. When dissolved in water, potassium sorbate converts to sorbic acid. Potassium sorbate's effectiveness as a preservative is directly related to pH levels of the product. In acidic products, having a pH of 6.5 or less, potassium sorbate is highly effective. The lower the pH, the less potassium sorbate is needed to produce the same amount of preservation.
Dosing
The amount of potassium sorbate required for product preservation depends upon the product, the local legislation and the actual shelf-life requirements. For example, the Food and Drug Administration has indicated that potassium sorbate is permitted as an optional ingredient in foods in amounts of less than 0.1 percent by weight, or 0.2 percent in total combination with other preservatives.
Toxicity
Potassium sorbate might have some potential toxic and cancer-causing effects. As reported by the Cosmetic Database, reports from 1977 and 1984 show positive tests for mutations caused by potassium sorbate in laboratory studies using human tissue culture cells. At high doses, potassium sorbate can cause kidney or renal system problems, and brain, nervous system or behavioral effects as well. Potassium sorbate does not appear to be an environmental toxin, however.
Allergies
Potassium sorbate does cause allergic reactions in some people. When used in shampoos and toothpaste, it can elicit a skin or respiratory allergic reaction. At high concentrations, it can irritate eyes, nose, throat and skin. Common reactions include contact dermatitis, resulting in raised itchy patches of skin called wheals, redness, hives, rashes and swelling.
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