Potassium Metabisulphite
K₂S₂O₅ | CAS: 16731-55-8 | HS: 28321000
Product Description
Potassium Metabisulphite (Potassium Pyrosulphite, E224) is the potassium counterpart of sodium metabisulphite, widely preferred in winemaking and brewing because it adds potassium rather than sodium to the finished product. Upon dissolution, it releases sulphur dioxide (SO₂) which protects wine and beer from oxidation and microbial spoilage — preventing browning, off-flavour development, and secondary fermentation. It is a critical tool for winemakers to control yeast activity, inhibit bacteria, and extend shelf life. Beyond beverages, it is used as an antioxidant preservative in dried fruits and vegetables (E224), as a reducing agent in gold precipitation (Merrill-Crowe process), in photographic developer solutions, and as a dechlorinating agent in water treatment. MITCHEM supplies food and technical grades.
Applications by Industry
Primary SO₂ source for winemaking — added to must, wine, and equipment rinse solutions to prevent oxidation, inhibit spoilage organisms, and stabilise colour; typical addition 50–200 mg/L.
Prevents enzymatic browning and microbial growth in dried fruits (apricots, raisins), fruit juices, shrimp, and seafood products; approved by FDA/EFSA as E224.
Reducing agent in the Merrill-Crowe process for precipitating gold from cyanide leach solutions; reduces Au(CN)₂⁻ to metallic gold for recovery in mining operations.
Reducing agent in photographic developer solutions to prevent aerial oxidation; used in analytical chemistry as a titrimetric reducing standard.