Potassium benzoate

Potassium benzoate, the potassium salt of benzoic acid, is a food preservative that inhibits the growth of mold, yeast and some bacteria. It works best in low-pH products, below 4.5, where it exists as benzoic acid.

Acidic foods and beverages such as fruit juice (citric acid), sparkling drinks (carbonic acid), soft drinks (phosphoric acid), and pickles (vinegar) are preserved with potassium benzoate.

It is approved for use in most countries including Canada, the U.S., and the EU, where it is designated by the E number E212. In the EU, it is not recommended for consumption by children.

Mechanism of food preservation
The mechanism of food preservation begins with the absorption of benzoic acid into the cell. If the intracellular pH changes to 5 or lower, the anaerobic fermentation of glucose through phosphofructokinase is decreased by 95%.

Safety and health
In combination with ascorbic acid (vitamin C), sodium and potassium benzoate may form benzene, a known carcinogen. Heat, light and shelf life can affect the rate at which benzene is formed. The Food and Drug Administration was performing tests in 2006, but the Environmental Working Group is calling for the FDA to publicly release all tests and use their authority to force companies to reformulate to avoid the potential benzene forming combination.

Potassium Benzoate (or E212) was recently described by the Food Commission, who campaign for 'safer, healthier food in the UK', as "mildly irritant to the skin, eyes and mucous membranes".

Cats have a significantly lower tolerance to benzoic acid and its salts than rats and mice.