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Potassium Metabisulfite — Hidden Processing Agent — Is It Vegan?

Also known as: Potassium pyrosulphite, E224, KMBS, Campden tablet (contains KMBS or SMBS)

Vegan

No animals or animal-derived substances are involved in producing this agent.

Not required on labels

Products containing sulphites above 10 ppm must declare 'contains sulphites' in EU and UK law. E224 may appear in the ingredient list of wines.

Source

Chemically synthesised from potassium hydroxide and sulphur dioxide. No animal products involved.

Used In

Wine production (antioxidant and antimicrobial), beer brewing (sterilising equipment, killing wild yeast), cider production, fruit juice preservation, winemaking.

How to Avoid

No need to avoid — KMBS is vegan. Sulphite sensitivity (distinct from vegan status) affects some people, particularly those with asthma.

Editorial Notes

Potassium metabisulfite is one of the most important preservatives in winemaking. Dissolved in water it forms sulphurous acid, which inhibits bacteria and oxidation. 'Campden tablets' used in home winemaking and brewing typically contain KMBS or SMBS. Low- and no-sulphite wines exist but may be less stable microbiologically.