Potassium Metabisulfite E224
sulfite — Primarily synthetic.
Dipotassium disulfite
CAS: 16731-55-8
Factual Regulatory Reference
This database provides factual regulatory information compiled from official government sources. It does not constitute medical, nutritional, or safety advice. Regulatory status varies by country and is subject to change. Always refer to your local regulatory authority for the most current information.
? Did You Know?
Beyond food, Potassium Metabisulfite is also used in cosmetics, medicine, industrial applications, household products. Its versatility makes it one of the most multi-purpose chemical compounds in everyday life.
To reach the Acceptable Daily Intake limit, a 60kg adult would need to consume approximately ~0.1 tablet Campden tablets for wine (standard tablet ~440mg metabisulfite) in a single day. (This is a mathematical illustration, not a safety recommendation.)
Regulatory Analysis
The regulatory treatment of potassium metabisulfite highlights how dramatically sulfite labeling thresholds vary across jurisdictions, with the 10 mg/kg trigger in the EU contrasting with different cutoffs and exemptions elsewhere, creating a patchwork that leaves sulfite-sensitive travelers and consumers of imported goods particularly vulnerable. The preference for the potassium salt over the sodium form in winemaking -- driven by sodium reduction goals rather than safety differences -- illustrates how non-toxicological considerations influence additive selection within a chemically equivalent group. The EFSA/JECFA decision to maintain only a 'temporary' group ADI since 2016 signals ongoing discomfort with the sulfite safety database, particularly regarding the gap between population-level risk assessment and the outsized impact on the sensitive minority.
Detailed Regulatory Assessment
European Union (EFSA)
MANDATORY declaration 'contains sulfites' when total SO₂ ≥ 10 mg/kg or 10 mg/L. Temporary group ADI with safety concerns for high consumers. Maximum use levels: fresh/dried fruits/vegetables 10-2000 mg/kg.
United States (FDA)
MANDATORY 'contains sulfites' declaration when ≥10 ppm SO₂. Banned from fresh fruits and vegetables for raw consumption (1986).
Japan (MHLW)
Part of sulfite group; allergen labeling required
Acceptable Daily Intake (ADI)
International Standard (JECFA)
mg/kg body weight per day
European Standard (EFSA)
Everyday Perspective
For a 60kg adult, this limit is roughly equivalent to consuming:
Natural Occurrence
This additive is not known to occur naturally in significant quantities.
Manufacturing
Produced by passing sulfur dioxide (SO₂) through a solution of potassium carbonate or potassium hydroxide. The solution is concentrated and crystallized to yield potassium metabisulfite (K₂S₂O₅). Upon dissolution in water, it releases sulfur dioxide and forms potassium bisulfite. Preferred over sodium form in wine-making to avoid adding sodium.
Applications Beyond Food
Limited use in cosmetics
Used as an antioxidant in some pharmaceutical preparations
Used in photography, textile processing, and water treatment
Main ingredient in Campden tablets for home wine-making and brewing