E223: Sodium metabisulphite

What is E223?

Sodium metabisulphite is a white crystalline salt that releases sulphur dioxide when it dissolves in water or comes into contact with acid. Labelled E223, it belongs to the sulphite group of additives.

Origin and production

It is manufactured by reacting sulphur dioxide with sodium hydroxide or sodium carbonate solutions and crystallising the product.

Why is it used?

Sodium metabisulphite is a preservative and antioxidant. It prevents black spot discolouration on prawns and shrimps, softens dough in some biscuits and crackers, and protects the colour of fruit and vegetable products, frozen foods and some snacks.

Vegan, vegetarian and halal

It is a synthetic mineral-based compound suitable for vegans and vegetarians, and is not normally a concern for halal or kosher diets.

Safety and regulation

Sodium metabisulphite is authorised in the EU, and sulphites above 10 mg/kg or 10 mg/litre must be declared as allergens because they can trigger reactions in sensitive people, particularly some asthmatics. In its re-evaluation of sulphites, EFSA identified a risk of exceeding the acceptable daily intake for some population groups.

Common in