Sulphur Dioxide (Wine Preservative) — Hidden Processing Agent — Is It Vegan?

Vegan status: Vegan

Also known as: SO₂, E220, Sulfites, Sulphites, Metabisulfite breakdown product

Source

Produced by burning elemental sulphur or as a byproduct of various industrial processes. Also produced naturally by yeast during fermentation. Entirely inorganic.

Used in

Wine production (most important preservative — antioxidant and antimicrobial), cider, dried fruit (prevents browning), some fruit juices, seafood processing.

Appears on label: No. Products containing sulphites above 10 ppm must declare 'contains sulphites' or 'contains sulfites' in EU, UK, and US law. A mandatory allergen declaration that appears on wine labels.

How to avoid

No need to avoid from a vegan perspective — sulphur dioxide is vegan. Low-SO₂ and zero-added-sulphite wines are available for those with sulphite sensitivity.

Notes

Sulphites are the most important preservative in the wine industry. All wine contains some sulphites from natural yeast fermentation — even 'sulphite-free' wines contain trace amounts. The 'contains sulphites' label is mandatory and is one of the few processing agent declarations required on wine. Some consumers confuse the sulphite warning with an indication of non-vegan content — the two are unrelated.