Calcium hydrogen sulphite

Calcium hydrogen sulphite is a sulphiting compound used as a preservative in beer and other beverages, where it prevents oxidative deterioration and microbial spoilage by releasing sulphur dioxide. It was historically used more broadly in food processing before the regulatory consolidation of sulphite additives, and remains listed as a permitted preservative in certain applications under EU food additive regulations. Its mechanism of action is the same as all sulphite preservatives: SO₂ release inhibits enzymatic browning enzymes and suppresses microbial growth.

JECFA evaluated calcium hydrogen sulphite as part of the broader sulphite group assessment in 1967, applying the group ADI of 0.7 mg/kg body weight per day expressed as SO₂. This shared limit manages total exposure from all sulphite sources in the diet. The same allergen concern applicable to all sulphite additives applies to E227: sulphites are among the recognised major food allergens under EU law, and sensitive individuals — particularly those with asthma — can react severely to sulphite exposure.

Calcium hydrogen sulphite is approved in the EU as E227 for specific beverage and food applications at regulated levels. The EU's mandatory allergen labelling requirements ensure that sulphites above threshold concentrations are declared on packaging. Like other less commonly encountered sulphite salts, E227 is functionally equivalent to more common forms such as sodium metabisulphite (E223) in terms of SO₂ release and allergy risk. Brewers and beverage manufacturers historically used calcium hydrogen sulphite for its combined preservative and mineral-correcting properties in fermented beverages, though it has been largely superseded by other sulphite forms in modern applications.