Calcium bisulphite

Calcium bisulphite is a calcium-containing sulphiting agent that releases sulphur dioxide under acidic conditions, functioning as a preservative and antioxidant in food. It inhibits enzymatic browning reactions, suppresses microbial activity, and prevents oxidative deterioration in a range of food products including beverages, fruit products, and certain processed vegetables. The calcium component is nutritionally inert at the trace levels present after SO₂ release.

JECFA assessed calcium bisulphite within the sulphite additive group in 1967, establishing a group ADI of 0.7 mg/kg body weight per day expressed as SO₂ for all sulphite compounds collectively (E220–E228). The conservative ADI reflects both general toxicological findings and the well-documented sensitivity reactions in susceptible individuals. Sulphite-sensitive asthmatic consumers can experience significant bronchoconstriction and other respiratory symptoms upon SO₂ exposure at levels below the ADI.

Calcium bisulphite is approved in the EU as E226 for specific food applications. Like all sulphite additives, its presence in food above 10 mg/kg SO₂ requires mandatory allergen labelling under EU food law, ensuring that sulphite-sensitive consumers can identify products to avoid. Calcium bisulphite is not as widely encountered in retail products as sodium metabisulphite (E223) or potassium metabisulphite (E224), which dominate the wine and dried fruit preservation markets, but carries identical allergen advisory obligations. Consumers with sulphite sensitivity should treat all E220–E228 additives with equal caution.