Sodium metabisulfite
Sodium metabisulfite suppliers and sourcing guide
Sodium metabisulfite is an inorganic sulfite salt that releases sulfur dioxide in water and acid. It is used to limit browning and microbial growth in dried fruit, wine, juices, shrimp and doughs, and as a dough conditioner in crackers and biscuits. It is made by reacting sulfur dioxide with sodium carbonate or sodium hydroxide solution and crystallizing the product. Brands buy it as a white crystalline powder in food, pharmaceutical or technical grades.
- Also known as
- Sodium pyrosulfite · Sodium disulfite · E223 · Na2S2O5
- Facts checked
- November 2026
Forms and grades of sodium metabisulfite
Suppliers sell different products under the same name. Specify the one you need.
Food grade powder
Fine white powder tested to Food Chemicals Codex specifications.
Granular
Coarser crystals with less dust, used in wineries and larger batching systems.
Pharmaceutical grade
USP/NF grade for drugs, supplements and some cosmetic products.
Technical grade
Grades for water treatment and industrial use, which should not be used in food.
What to check on the COA
Compare each result with your own specification when the lot arrives.
- Assay (iodometric titration)
- Na2S2O5 content, often also expressed as available sulfur dioxide, which falls as the product oxidizes.
- Iron
- Iron content, which affects color in finished products.
- Selenium, arsenic and lead
- Trace elements by ICP-MS against FCC limits.
- Thiosulfate
- A process impurity tested in the FCC monograph.
- Water-insoluble matter
- A check on insoluble residue that can cloud solutions.
Storage, lots and expiry
Storage and shelf life
Keep tightly sealed in a cool, dry, well-ventilated area away from acids and oxidizers; moisture and air convert it to sulfate and it gives off sulfur dioxide. Reseal opened bags promptly. Shelf life follows the supplier specification, and the sulfur dioxide assay of older stock should be rechecked before use.
Lots and expiry dates
Record the assay or available SO2 for each lot and dose by it, since strength drops with age and exposure. Track sulfite levels in finished products for labeling, and rotate stock FEFO.
Regulatory status
Facts from regulators and standards bodies, each linked to its source.
21 CFR 182.3766 lists sodium metabisulfite as GRAS when used in accordance with good manufacturing practice.
Source: ecfr.gov (opens in a new tab)The same section says it is not used in meats, in foods recognized as a source of vitamin B1, or on fruits or vegetables served or sold raw or presented as fresh.
Source: ecfr.gov (opens in a new tab)21 CFR 101.100(a)(4) considers added sulfiting agents, including sodium metabisulfite, as present in an insignificant amount only if none is detectable in the finished food, and defines a detectable amount as 10 ppm or more of sulfite.
Source: ecfr.gov (opens in a new tab)Health Canada's List of Permitted Preservatives includes sodium metabisulphite.
Source: canada.ca (opens in a new tab)
This is general information, not regulatory advice. Status differs by country and by how the ingredient is used, so check the rules for your product and market.
Sodium metabisulfite suppliers
Manufacturers and distributors whose own websites say they sell it.
We are checking sodium metabisulfite suppliers now
Every listing is checked against the supplier’s own website before it goes live, so this list fills in over the coming weeks. The specs and COA checklist above are ready today.
Sell sodium metabisulfite? Request a listingFrequently asked questions
What forms of sodium metabisulfite can brands buy?
Common forms include food grade powder, granular, pharmaceutical grade and technical grade. Ask each supplier for the specification sheet of the exact grade they quote.
What should the COA for sodium metabisulfite include?
Expect assay (iodometric titration), iron, selenium, arsenic and lead, thiosulfate and water-insoluble matter, each with its method, specification and result for that lot.
How should sodium metabisulfite be stored?
Keep tightly sealed in a cool, dry, well-ventilated area away from acids and oxidizers; moisture and air convert it to sulfate and it gives off sulfur dioxide. Reseal opened bags promptly. Shelf life follows the supplier specification, and the sulfur dioxide assay of older stock should be rechecked before use.
What is the regulatory status of sodium metabisulfite?
21 CFR 182.3766 lists sodium metabisulfite as GRAS when used in accordance with good manufacturing practice. The same section says it is not used in meats, in foods recognized as a source of vitamin B1, or on fruits or vegetables served or sold raw or presented as fresh. 21 CFR 101.100(a)(4) considers added sulfiting agents, including sodium metabisulfite, as present in an insignificant amount only if none is detectable in the finished food, and defines a detectable amount as 10 ppm or more of sulfite. Health Canada's List of Permitted Preservatives includes sodium metabisulphite.
More acids, preservatives and leavening
- Citric acid2-hydroxy-1,2,3-propanetricarboxylic acid · E330
- Malic acidDL-malic acid · L-malic acid
- Lactic acid2-hydroxypropanoic acid · L(+)-lactic acid
- Tartaric acidL-(+)-tartaric acid · 2,3-dihydroxybutanedioic acid
- Fumaric acidtrans-butenedioic acid · E297
- Acetic acidethanoic acid · glacial acetic acid
- Phosphoric acidorthophosphoric acid · E338
- Glucono-delta-lactoneGDL · glucono delta-lactone
- Adipic acidhexanedioic acid · 1,4-butanedicarboxylic acid
- Sodium citratetrisodium citrate · trisodium citrate dihydrate
- Sodium lactatesodium 2-hydroxypropanoate · E325
- Sodium acetatesodium ethanoate · E262
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