Sodium sulfite is an inorganic reducing agent and preservative, also spelled sodium sulphite. It is used as an oxygen scavenger in boiler water treatment, a preservative (E 221) in food and beverage applications, and a bleaching agent in textiles. Other uses include photographic development, dye manufacture and silvering glass. It is a white crystalline powder. The catalogue lists food and technical grades in 25 kg bags or drums and 500 kg or 1000 kg big bags. Food use as E 221 is subject to the applicable food-additive specification and permitted-use conditions.