Potassium metabisulfite (K₂S₂O₅) is a white crystalline powder with strong reducing and preservative properties. It releases **sulfur dioxide (SO₂)** when dissolved in water, making it useful in various industries. Here are its key applications:
1. Food & Beverage Industry
- Preservative & Antioxidant
- Prevents microbial growth and oxidation in **wine, beer, cider, fruit juices, and dried fruits**.
- Extends shelf life by inhibiting bacteria, yeast, and mold.
- Anti-Browning Agent
- Used in processed fruits, vegetables, and seafood to prevent discoloration.
- Disinfectant in Brewing
- Sanitizes winemaking equipment (barrels, tanks) to avoid contamination.
2. Pharmaceutical & Cosmetics
- Antiseptic & Preservative
- Added to medicinal syrups, injectables, and eye drops to prevent microbial growth.
- Used in shampoos, creams, and lotions as a mild preservative.
3. Water Treatment
- Dechlorination Agent
- Removes excess chlorine from drinking water and wastewater.
- Disinfectant
- Controls algae and bacteria in swimming pools and industrial water systems.
4. Industrial & Chemical Uses
- Reducing Agent
- Used in textile dyeing, photography (film development), and gold extraction.
- Bleaching Agent
- Helps bleach sugar, starch, and paper pulp.
- Chemical Synthesis
- Used to produce thiosulfates and other sulfur-containing compounds.
5. Other Applications
- Agriculture: Post-harvest treatment to prevent spoilage of fruits and vegetables.
- Laboratory Reagent: Used in analytical chemistry (e.g., iodometric titrations).
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