Potassium metabisulfite
Potassium metabisulfite suppliers and sourcing guide
Potassium metabisulfite is an inorganic sulfite salt that releases sulfur dioxide in water and acid, used mainly in winemaking, cider, beer and juice to control unwanted microbes and oxidation, and to sanitize equipment. It is made by reacting sulfur dioxide with potassium hydroxide or potassium carbonate solution and crystallizing the product. Brands buy it as a white crystalline powder or granules, and home and craft producers often use it as pressed tablets.
- Also known as
- Potassium pyrosulfite · Potassium disulfite · E224 · K2S2O5
- Facts checked
- November 2026
Forms and grades of potassium metabisulfite
Suppliers sell different products under the same name. Specify the one you need.
Food grade powder
Fine crystalline powder tested to Food Chemicals Codex specifications.
Granular or crystal
Coarser grades with less dust, common in wineries.
Effervescent tablets
Pre-measured tablets for dosing small batches of wine, cider and must.
Technical grade
Industrial grades for photography and water treatment, not for food use.
What to check on the COA
Compare each result with your own specification when the lot arrives.
- Assay (iodometric titration)
- K2S2O5 content or available sulfur dioxide, the figure used to calculate doses.
- Iron
- Iron content, which can affect color and stability in wine and juice.
- Selenium, arsenic and lead
- Trace elements by ICP-MS against FCC limits.
- Thiosulfate
- A process impurity tested in the FCC monograph.
- Appearance
- White crystals without yellowing or strong caking, which signal moisture exposure.
Storage, lots and expiry
Storage and shelf life
Store sealed in a cool, dry, ventilated area away from acids; exposure to air and moisture oxidizes it and releases sulfur dioxide, so strength falls once a container is opened. Keep tablets in their sealed packaging until use. Shelf life follows the supplier specification, with a retest of available SO2 for aged stock.
Lots and expiry dates
Record available SO2 for each lot and adjust additions to it. Note sulfite levels in finished drinks for labeling, and rotate stock FEFO.
Regulatory status
Facts from regulators and standards bodies, each linked to its source.
21 CFR 182.3637 lists potassium 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 and vegetables served or sold raw or presented as fresh.
Source: ecfr.gov (opens in a new tab)21 CFR 101.100(a)(4) names potassium metabisulfite among the sulfiting agents and defines a detectable amount as 10 ppm or more of sulfite in the finished food.
Source: ecfr.gov (opens in a new tab)Health Canada's List of Permitted Preservatives includes potassium 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.
Potassium metabisulfite suppliers
Manufacturers and distributors whose own websites say they sell it.
We are checking potassium 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 potassium metabisulfite? Request a listingFrequently asked questions
What forms of potassium metabisulfite can brands buy?
Common forms include food grade powder, granular or crystal, effervescent tablets and technical grade. Ask each supplier for the specification sheet of the exact grade they quote.
What should the COA for potassium metabisulfite include?
Expect assay (iodometric titration), iron, selenium, arsenic and lead, thiosulfate and appearance, each with its method, specification and result for that lot.
How should potassium metabisulfite be stored?
Store sealed in a cool, dry, ventilated area away from acids; exposure to air and moisture oxidizes it and releases sulfur dioxide, so strength falls once a container is opened. Keep tablets in their sealed packaging until use. Shelf life follows the supplier specification, with a retest of available SO2 for aged stock.
What is the regulatory status of potassium metabisulfite?
21 CFR 182.3637 lists potassium 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 and vegetables served or sold raw or presented as fresh. 21 CFR 101.100(a)(4) names potassium metabisulfite among the sulfiting agents and defines a detectable amount as 10 ppm or more of sulfite in the finished food. Health Canada's List of Permitted Preservatives includes potassium 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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