E224: Potassium Metabisulfite (Campden Salt)

Direct Answer

E224 (Potassium Metabisulfite / K2S2O5) is a white crystalline powder releasing 57.6% sulfur dioxide by weight when dissolved in acidic liquids. INS 224, ADI is 0.7 mg/kg bw/day, the premier sanitizing and stabilizing agent in commercial winemaking.

Source: OIV / EFSA · Last reviewed Aug 28, 2026

Specs

E-Number Code	E224
INS / Codex Number	INS 224
Functional Class	Preservative, Antioxidant, Sanitizer
Acceptable Daily Intake (ADI)	0.7 mg / kg body weight per day (as SO2 equivalent)
Chemical Formula	K2S2O5
Primary Mechanism	Releases free SO2 and potassium ions, neutralizing wild yeasts and preventing enzymatic must oxidation
Common Target Foods	Grape must, commercial wines, ciders, lemon juice concentrates, dried fruit processing
Dietary Compliance	Vegan, Halal, Kosher (Allergen labeling required)
Safety Approval	EFSA Authorized / FDA GRAS (21 CFR 182.3637)

Precision Dosing in Winemaking (Campden Tablets)

Adding 100mg of K2S2O5 per liter of grape juice yields approximately 50 mg/L (PPM) of total SO2, eliminating wild bacteria before pitching cultured Saccharomyces cerevisiae.