Potassium Metabisulphite K2S2O5, is a white crystalline powder or white granules with a pungent sulfur odour. The main use for the chemical is as an antioxidant or chemical sterilant. Potassium bisulphite belongs to the sulfite group of preservatives. Sulfites are characterized by containing sulfur and oxygen. Potassium bisulphite is also referred to as potassium metabisulphite or potassium metabisulphite powder. This preservative is found naturally. Known as an antioxidant preservative, potassium bisulfite has some antioxidant capabilities,meaning it can fight inflammation causing free radicals in the body.