Calcium sulfate
Calcium sulfate suppliers and sourcing guide
Calcium sulfate is a calcium salt that occurs naturally as gypsum and anhydrite. In food it is used as a tofu coagulant, a dough conditioner and yeast food, a calcium source, a firming agent for canned vegetables, and to adjust brewing water. Food grades are made from purified mined gypsum or by precipitation, and the anhydrous form is made by dehydrating gypsum. Brands buy it as a fine white powder in dihydrate or anhydrous form.
- Also known as
- Gypsum · Calcium sulfate dihydrate · Anhydrite · E516
- Facts checked
- November 2026
Forms and grades of calcium sulfate
Suppliers sell different products under the same name. Specify the one you need.
Dihydrate
CaSO4·2H2O, the common form for tofu, brewing and baking.
Anhydrous
Water-free calcium sulfate with a higher calcium content per kilogram.
Mined
Food grade made from purified natural gypsum; this is the form allowed in organic products.
Precipitated
Calcium sulfate made by chemical reaction, often with tighter impurity limits.
What to check on the COA
Compare each result with your own specification when the lot arrives.
- Assay (complexometric titration)
- CaSO4 content on a dried or ignited basis, per FCC.
- Loss on ignition or drying
- Confirms whether the lot is dihydrate or anhydrous.
- Fluoride
- Fluoride against the FCC limit, relevant for mined material.
- Lead, arsenic and selenium
- Trace elements by ICP-MS, which can vary with the mine source.
- Particle size
- Sieve or laser analysis, which affects suspension in soy milk and dough.
Storage, lots and expiry
Storage and shelf life
Store sealed in a dry area; the powder is stable but cakes when damp, and the anhydrous form slowly picks up water. Shelf life follows the supplier specification, with a retest of moisture and appearance for older stock.
Lots and expiry dates
Record hydrate form, source (mined or precipitated) and particle size for each lot, since each affects dose and texture, and note mined origin for organic use. Rotate stock FEFO.
Regulatory status
Facts from regulators and standards bodies, each linked to its source.
21 CFR 184.1230 describes calcium sulfate, also known as plaster of Paris, anhydrite and gypsum, and affirms it as GRAS with maximum levels by food category.
Source: ecfr.gov (opens in a new tab)The GRAS affirmation sets a good manufacturing practice maximum of 1.3 percent as served for baked goods.
Source: ecfr.gov (opens in a new tab)7 CFR 205.605(a) allows mined calcium sulfate as a nonsynthetic substance in organic products.
Source: ecfr.gov (opens in a new tab)Health Canada's List of Permitted Firming Agents includes calcium sulphate.
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.
Calcium sulfate suppliers
Manufacturers and distributors whose own websites say they sell it.
We are checking calcium sulfate 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 calcium sulfate? Request a listingFrequently asked questions
What forms of calcium sulfate can brands buy?
Common forms include dihydrate, anhydrous, mined and precipitated. Ask each supplier for the specification sheet of the exact grade they quote.
What should the COA for calcium sulfate include?
Expect assay (complexometric titration), loss on ignition or drying, fluoride, lead, arsenic and selenium and particle size, each with its method, specification and result for that lot.
How should calcium sulfate be stored?
Store sealed in a dry area; the powder is stable but cakes when damp, and the anhydrous form slowly picks up water. Shelf life follows the supplier specification, with a retest of moisture and appearance for older stock.
What is the regulatory status of calcium sulfate?
21 CFR 184.1230 describes calcium sulfate, also known as plaster of Paris, anhydrite and gypsum, and affirms it as GRAS with maximum levels by food category. The GRAS affirmation sets a good manufacturing practice maximum of 1.3 percent as served for baked goods. 7 CFR 205.605(a) allows mined calcium sulfate as a nonsynthetic substance in organic products. Health Canada's List of Permitted Firming Agents includes calcium sulphate.
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