Potassium metabisulphite is a white to off-white crystalline powder with a characteristic sulphur dioxide (SO₂) odor. It is widely used as a preservative, antioxidant, disinfectant, and reducing agent in food and beverage processing, pharmaceuticals, water treatment, textiles, photography, and chemical industries. In aqueous solution, it releases sulphur dioxide, which provides antimicrobial and antioxidant pro