Potassium benzoate, the potassium salt of benzoic acid, is typically used by food manufacturers as a chemical preservative. It's sometimes used in place of a related preservative -- sodium benzoate -- to reduce the food's sodium content. Potassium benzoate helps fight food spoilage, and it can contribute to food's flavor, but like any food additive, it can cause allergic reactions in some people.

How It's Used

According to the U.S. Food and Drug Administration, potassium benzoate is "generally recognized as safe" and approved for use as a preservative as well as a flavoring agent. Adding just a small amount can help prevent the growth of mold, yeast and certain bacteria in foods. Because the compound imparts a tang to certain foods, it can also be used as a flavoring agent.

Where It's Found

Potassium benzoate is typically added to packaged foods, so look to the more processed aspects of your diet to find it. It's used to preserve carbonated soft drinks, cider, juices, jams, syrups and pickled foods. Potassium benzoate also occurs naturally in cranberries, so you'll also find it in cranberry juice, cranberry cocktail and cranberry sauce.

Past Controversy

When combined with ascorbic acid, or vitamin C, and sodium, potassium benzoate may form benzene, a known carcinogen. In 2007, results from a Center for Food Safety and Applied Nutrition sampling of soft drinks tested for benzene showed that some contained higher than acceptable levels of the compound. New standards are now in place, and according to the American Beverage Association, affected products have been reviewed and reformulated. With excessive exposure to heat and light or extended shelf life, products may still form small amounts of benzene, although it's likely not a safety concern.

Important to Note