It is used as a food additive, also known as E224. It is restricted in use and may cause allergic reactions in some sensitive persons.
Wine Potassium metabisulfite is a common
wine or
must additive, in which it forms sulfur dioxide (SO2). Sulfur dioxide is a disinfectant. It also acts as a potent
antioxidant, protecting both the color and delicate flavors of wine. A high dose would be 3 grams of potassium metabisulfite per six-gallon bucket of must or around 132 milligrams per liter (yielding roughly 75 ppm of SO2) prior to fermentation; then 6 grams per six-gallon bucket (150 ppm of SO2) at bottling. Some countries regulate the SO2 content of wines. Winemaking equipment is sanitized by spraying with a 1% SO2 (2 tsp potassium metabisulfite per L) solution.
Beer Potassium metabisulfite is sometimes used in the
brewing industry to inhibit the growth of wild
bacteria and
fungi. This step is called 'stabilizing'. It is also used to neutralize
monochloramine from tap water. It is used both by
homebrewers and commercial brewers alike. It is not used as much for brewing
beer, because the
wort is almost always boiled, which kills most microorganisms.
Other uses • Potassium metabisulfite is sometimes added to
lemon juice as a
preservative. • Potassium metabisulfite is used in the textile industry for dyeing and cotton printing. • Potassium metabisulfite is sometimes used to precipitate gold from solution in
aqua regia (as an alternative to
sodium sulfite). • It is a component of certain photographic developers and solutions used in photographic processing, keeping active developing species from contact with oxygen. • It is used as a bleaching agent in the production of coconut cream. • It is used in some pickles as a preservative. • It is used in tint etching iron-based metal samples for microstructural analysis. • It is used in
aam papad as a preservative. ==Chemical structure==