Potassium benzoate (E212), 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. Potassium benzoate is stable at room temperature under normal storage conditions. Due to its slight hygroscopicity, it should be placed in a sealed container and should avoid exposure to high humidity and high temperature.