Potassium metabisulfite

Potassium metabisulfite is a chemical compound with the formula K2S2O5. It is a white crystalline powder with a strong sulfur odor. It is often used as a food preservative, sterilizing agent, and antioxidant.

Chemical Properties

Potassium metabisulfite is a salt of sulfurous acid. It is a strong reducing agent and can be easily oxidized. It is soluble in water and its aqueous solution is acidic. When heated, it decomposes to release sulfur dioxide, which is a toxic gas.

Uses

Potassium metabisulfite has a wide range of uses in various industries.

Food Industry

In the food industry, it is used as a preservative and antioxidant. It prevents the growth of bacteria, yeast, and molds in food products. It is also used in the production of wine, beer, and cider to prevent oxidation and preserve flavor.

Photography

In photography, potassium metabisulfite is used as a photographic fixer. It helps to remove unexposed silver halide from photographic film, thus preventing further development.

Water Treatment

Potassium metabisulfite is also used in water treatment processes. It is used to remove chlorine from water, which can interfere with other treatment processes.

Health Effects

Exposure to potassium metabisulfite can cause irritation to the eyes, skin, and respiratory tract. Ingestion can cause gastrointestinal disturbances. People with asthma or sulfite sensitivity should avoid exposure to this compound.

Regulation

In the United States, the Food and Drug Administration (FDA) has classified potassium metabisulfite as a "generally recognized as safe" (GRAS) substance when used in accordance with good manufacturing practices.

See Also

• Sodium metabisulfite
• Sulfur dioxide
• Food preservation