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 bisulfite belongs to the sulfite group of preservatives. Sulfites are characterized by containing sulfur and oxygen. Potassium bisulfite is also referred to as potassium metabisulphite or potassium metabisulphite powder. This preservative is found naturally in wine. Known as an antioxidant preservative, potassium bisulfite has some antioxidant capabilities,meaning it can fight inflammation causing free radicals in the body.