The main use for the chemical is as an antioxidant or chemical sterilant. It is a disulfite and is chemically very similar to sodium metabisulfite, with which it is sometimes used interchangeably. Potassium metabisulfite is generally preferred out of the two as it does not contribute sodium to the diet. It is used as a food additive, also known as E224. It is restricted in use and may cause allergic reactions in some sensitive persons.Potassium metabisulfite is an inhibitor of the polyphenol oxidase enzyme. Potassium metabisulfite is a white granular or powdery solid with a sharp odor of sulfur dioxide. Decomposes at 150 to 190°C. Density 2.3 g/cm3. Contact severely irritates skin, eyes, and mucous membranes. Low toxicity. Used as a food preservative and an antioxidant.