Description
The most commercially important sulfite preservative globally, generating sulfur dioxide in solution to deliver antimicrobial, antioxidant, and enzymatic-browning-prevention functions in a single ingredient. The standard sulfiting agent in winemaking, dried fruit, and seafood processing.
White crystalline powder with characteristic sulfur dioxide odor. Highly water-soluble (approximately 540 g/L at 20 °C). One gram releases approximately 0.67 grams of sulfur dioxide on dissolution.
We supply food-grade, pharmaceutical-grade, and industrial-grade Sodium Metabisulfite from manufacturers in China holding ISO, Halal, Kosher and other certifications relevant to the product and production.
Common market grades include Standard Food Grade (FCC compliant) for winemaking, dried fruit, and seafood, Pharmaceutical Grade meeting BP/USP/EP specifications, Photographic Grade for film and print processing, and Industrial Grade for water treatment and ore processing.
Bulk and reduced-MOQ shipments. Batch-level COA covering assay, iron, heavy metals, and microbiology.
Introduction
Sulfite preservation predates the modern food industry. Wine sulfiting was practiced in Roman times by burning sulfur in wine amphorae, the technique that generated sulfur dioxide in the wine and prevented spoilage. Modern Sodium Metabisulfite delivers the same chemistry through controlled solid handling.
Industrial production proceeds by reaction of sodium carbonate or sodium hydroxide with sulfur dioxide gas, followed by controlled crystallization. The disodium pyrosulfite (Na2S2O5) structure releases two molecules of sulfur dioxide and one of sodium sulfite per molecule in aqueous solution.
Regulated as E223 in the EU within the broader sulfite family (E220 through E228), classified as Generally Recognized as Safe by the U.S. FDA with the exception of use on fresh fruits and vegetables intended to be sold raw, and approved by JECFA with an Acceptable Daily Intake of 0.7 mg per kg body weight expressed as sulfur dioxide.
The molecule delivers three simultaneous functions: antimicrobial activity (active against bacteria, yeasts, and molds at low pH), antioxidant activity (oxygen scavenging and free-radical quenching), and enzymatic-browning inhibition (suppression of polyphenol oxidase). This multifunctionality is the principal reason sulfites remain irreplaceable in winemaking and dried fruit despite ongoing reformulation pressure.
Regulatory positioning is constrained by sulfite-allergy concerns. U.S. and EU regulations require declared labeling when residual sulfite exceeds 10 mg per kg, and sulfite-free or reduced-sulfite positioning is increasingly visible in premium wine and dried fruit categories. Use in lettuce and fresh produce at retail is prohibited in the US.
Where it is used
- Winemaking: the global standard sulfiting agent for must treatment, fermentation control, and finished-wine preservation
- Dried fruit preservation: apricots, raisins, prunes, and dried apple slices; prevents enzymatic browning
- Seafood processing: shrimp, lobster, and prawn black-spot prevention
- Beer brewing: yeast handling, oxygen scavenging, and finished-beer stability
- Sugar production and refining: clarification and decolorization
- Soft drink and juice antioxidant
- Pharmaceutical antioxidant in injectable and oral formulations
- Water treatment: dechlorination of process water and effluent
- Photographic developer and fixer preservation
- Ore flotation and gold processing in mining applications
Technical data
| Item | Specification |
|---|---|
| Appearance | White crystalline powder |
| Assay (as Na2S2O5) | ≥ 97.0% |
| Sulfur dioxide content | ≥ 65.0% |
| Iron | ≤ 30 mg/kg |
| Selenium | ≤ 10 mg/kg |
| Heavy metals (as Pb) | ≤ 5 mg/kg |
| Arsenic | ≤ 3 mg/kg |
| Thiosulfate | ≤ 0.1% |
| Particle size | Per customer specification |
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