Potassium Metabisulfite

Other Trading Names:

  • Potassium Metabisulfite
  • Potassium Pyrosulfite
  • KMS

CAS Number: 16731-55-8

HS Code: 2832200000

Types of Packaging:

  • 25kg/Bag
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Potassium Metabisulfite

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Chemical Name

Potassium Metabisulfite



Molecular Formula


CAS Number



White to slightly yellow Powder/Solid

Grade Standard

Food Grade, Industrial Grade, Technical Grade


H2O: 0.1 M at 20 °C, clear, colorless

Melting Point



2.34 g/cm³

Chemical Description 

  • Potassium Metabisulfite (KMS) is a chemical compound with the formula K2S2O5. It is commonly used as a preservative and antioxidant in the food and beverage industry, notably in wine and beer making, to prevent oxidation and preserve flavor.
  • KMS is a white or yellowish crystalline powder that readily dissolves in water, releasing sulfur dioxide gas, which contributes to its preservative properties.
  • In the wine industry, KMS is used to inhibit the growth of bacteria and wild yeast during fermentation, ensuring the production of high-quality wines. It also serves as a powerful antioxidant, protecting the color and flavor of wines during storage.
  • In beer brewing, Potassium Metabisulfite is utilized to sterilize equipment and as a stabilizing agent to extend shelf life.
  • Beyond its applications in food and beverage preservation, KMS is used in the textile industry for bleaching and neutralizing chlorinated water. In the paper industry, it acts as a bleaching agent to whiten paper pulp.
  • It also plays a critical role in water treatment processes, where it is used to remove excess chlorine and as a reagent in the detoxification of wastewater.
  • Potassium Metabisulfite finds use in photography as a photographic fixer, helping to dissolve undeveloped silver halides from exposed negatives or prints.
  • Additionally, it is employed in various industrial applications as a source of sulfur dioxide, useful in the synthesis of chemicals and as a reducing agent.
  • Due to its strong antioxidant and preservative capabilities, KMS is essential in food processing, particularly in preserving dried fruits and preventing browning. It is also applied in the cosmetic industry as a preservative in some products.
  • Potassium Metabisulfite is recognized for its effectiveness in various applications, owing to its antioxidant, antibacterial, and preservative properties. Despite its widespread use, it is important to handle KMS with care due to its potential to release sulfur dioxide gas, which can be irritating to the respiratory tract.
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Potassium Metabisulfite