My diet:

E516 Calcium sulfate

E516Flour treatment agentsOrigin: Mineral
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The short answer
Calcium sulfate (E516) is purified gypsum. It sets many Chinese-style tofus, feeds yeast and carries other ingredients. It is a mineral considered safe in food.
Generally safe

Fine for most people at normal amounts.

E-numberE516
Comes fromMineral
What it doesFlour treatment agents
Glycemic index—
Daily limitNot set
Also calledCalcium sulfate, Gypsum

Rules by country

🇺🇸 US FDAApproved
🇪🇺 European UnionApproved
🇨🇦 Health CanadaApproved
CaliforniaNo extra rules

Calcium sulfate is GRAS in the US and approved in the EU and Canada as a firming agent, flour treatment, yeast food and carrier. The dose in tofu or bread is a calcium source, not a bleach.

Daily limit: Experts haven’t set a number because normal food amounts are far below any level of concern.

What is it?

Added to hot soy milk, calcium sulfate makes proteins clump into a tender curd. Bakeries use a little in dough as a calcium source and yeast nutrient. It is not the plaster on a wall; food grade is refined and dosed.

Where it comes from: Food-grade calcium sulfate is purified gypsum, the same mineral as plaster, cleaned until it meets food specifications. Tofu makers know it as a coagulant.

Why it’s in food

  • Sets tofu curds
  • Adds calcium to bread
  • Feeds yeast
  • Carries powders

Often found in

Firm tofuBreadCanned vegetablesBaking powderShredded cheeseBeer

Also listed as: Calcium sulfate, Gypsum, Food-grade gypsum, Terra alba

Health & gut impact

CalciumBenefit

Calcium sulfate contributes calcium. Traditional gypsum tofu is one food source of it.

NIH Office of Dietary Supplements, Calcium

Not plaster dustConcern

Food-grade calcium sulfate is purified. Construction plaster can contain additives that do not belong in soy milk.

21 CFR 184.1230

For tofu at home

For your pantry
Pantry staple

Food-grade gypsum

Calcium sulfate sold for tofu.

Shop food-grade gypsum Opens your country’s Amazon store
Pantry staple

Nigari flakes

Magnesium chloride, if you want the other classic coagulant.

Shop nigari Opens your country’s Amazon store
Pantry staple

Dry soybeans

The other half of a tofu recipe.

Shop dry soybeans Opens your country’s Amazon store

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What can I use instead?

Calcium chloride

Ratio: A firmer, saltier set

Best for: Cheese and pickles

Nigari (magnesium chloride)

Ratio: Tofu recipes differ

Best for: A different tofu texture

Related

More flour treatment agents:

Azodicarbonamide (ADA) E927aAzodicarbonamide (ADA, E927a) is a dough conditioner that's banned in the EU but still legal in US bread. Baking turns some of it into semicarbazide, a possible carcinogen, so it's one to avoid.Best to avoidBenzoyl peroxide E928Benzoyl peroxide (E928) bleaches flour white overnight. It's legal in the US and Canada but banned in the EU, and it destroys some of the vitamin E in flour. It's not on the label in most cases.Use in moderationEnriched flourEnriched flour is white wheat flour with B vitamins and iron added back after milling. It contains gluten, it raises blood sugar, and it is a staple food rather than a controversial chemical.Use in moderationL-Cysteine E920L-cysteine (E920) softens dough in bagels and pizza crust. It's often made from duck feathers or pig hair, so it's only reliably vegan or halal when certified.Use in moderation

Common questions

Can I use wall plaster to make tofu?

No. Use food-grade calcium sulfate. Building plaster can contain additives that are not food.

Is Calcium sulfate safe?

Generally safe (94/100). Calcium sulfate is GRAS in the US and approved in the EU and Canada as a firming agent, flour treatment, yeast food and carrier. The dose in tofu or bread is a calcium source, not a bleach.

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Scientific sources & regulatory citations
  • 21 CFR 184.1230 (US FDA)
  • EFSA OpenFoodTox: E516
  • NIH Office of Dietary Supplements, Calcium
  • 21 CFR 184.1230

INS 516 · CAS 7778-18-9