The colourless (white) sulphur-smelling powder (also potassium metabisulphite, potassium disulphite or KPS for short) is the potassium salt of sulphurous acid. Under acidic conditions, the compound sulphur dioxide is split off (there is no effect in pure water). It is mainly used as an antioxidant, preservative and colour stabiliser in the food industry (declared by the code E 224) such as in fruit juices. KPS is also used in winemaking to sulphurise mash, grape must or wine. The potassium introduced promotes the precipitation of tartar. Furthermore, it is also used together with tartaric acid dissolved in water for the wet preservation of barrels or containers. See also under potassium and agents used in winemaking.
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