Is Sodium Metabisulfite (E223) Vegan?

Three jobs explain most sulfite use. Sulfites kill or suppress bacteria, yeast, and mold, which is why winemakers and juice producers rely on them. They block enzymatic browning, keeping dried apricots orange and cut potatoes pale instead of gray. They also mop up oxygen, protecting color and flavor over a long shelf life. The orange dried apricot is the clearest illustration.

Unsulfited apricots turn deep brown within weeks, and the two products sit side by side in health food shops at different prices. One use involves animals directly. Shrimp and prawns are dipped in metabisulfite solution on the boat to stop melanosis, the black spotting that forms at the head and joints. The additive itself stays mineral there, and the shellfish is what makes the product non-vegan.

EU rules list sulfur dioxide and sulfites among the fourteen declarable allergens, triggered once the product contains more than 10 mg per kilogram or liter expressed as sulfur dioxide. That threshold is why nearly every bottle of wine says "contains sulfites" while a packet of biscuits usually does not. Reactions concentrate in people with asthma, where a subset experience wheezing, chest tightness, or flushing.

True sulfite allergy in the immunological sense is rare, and most reactions are better described as intolerance. People with the enzyme disorder sulfite oxidase deficiency must avoid sulfites strictly. One point of confusion trips up wine drinkers. Sulfites in wine are vegan, and every fermentation produces some naturally even without addition. The vegan question in wine turns on fining agents, which are isinglass, gelatin, casein, or egg white, and those never appear on the label.