Sodium Metabisulphite

Sodium metabisulfite is a white or slightly yellowish crystalline powder. It is a salt of sulfurous acid, formed by combining sulfur dioxide with sodium carbonate or sodium hydroxide. It is often produced industrially through chemical synthesis.

Sodium metabisulfite is primarily used as a preservative and antioxidant in foods. It helps prevent spoilage by inhibiting the growth of bacteria and fungi, and it can also prevent browning in fruits and vegetables. It is commonly found in baked goods, dried fruits, and some beverages.

In the U.S., sodium metabisulfite is Generally Recognized As Safe (GRAS) by the FDA for use as an antimicrobial agent and antioxidant. It can cause allergic reactions in some individuals, particularly those with asthma, and may trigger sensitivity in people with sulfite allergies. The Joint FAO/WHO Expert Committee on Food Additives (JECFA) and the European Food Safety Authority (EFSA) have evaluated sulfites, including sodium metabisulfite, and established acceptable daily intakes. Evidence regarding the link between sulfites and asthma exacerbation is mixed, with some studies showing a correlation and others not.