Potassium Metabisulphite
Also known as: E224, Potassium metabisulfite
Sulfites including potassium metabisulfite (E224) trigger asthma attacks, hives, and rare anaphylaxis in sensitive individuals (~1% of population, ~5% of asthmatics). FDA banned sulfite use on fresh fruits/vegetables in 1986 after deaths linked to salad-bar sulfites.
What it is
Potassium metabisulfite (K2S2O5) — a sulfite salt that releases sulfur dioxide.
Preservative, antioxidant, antimicrobial; primarily used in winemaking and dried fruits.
Why it's flagged
- asthma triggers (severe and life-threatening)
- FDA banned on fresh produce
- destroys vitamin B1
- mandatory allergen-style declaration
What regulators actually say
"Sulfiting agents... are generally recognized as safe... except that they may not be used on fruits and vegetables intended to be served raw to consumers or to be presented to consumers as fresh."
"If a sulfiting agent has been added to a standardized food and is present at a level of 10 ppm or higher in the finished food, the presence of the sulfiting agent must be declared on the label."
Regulatory status
United States — FDA
GRAS for specified uses under 21 CFR 182.3766; banned on raw fresh fruits/vegetables (excluding fresh-cut potatoes); ≥10 ppm SO2 must be declared.
European Union — EFSA
Permitted as E224 with restrictions; EFSA group ADI 0.7 mg SO2/kg bw/day; allergen-style declaration required.
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