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E526 Calcium hydroxide (Slaked lime)

E526Acidity regulatorsOrigin: Mineral
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The short answer
Calcium hydroxide (E526) is food-grade slaked lime used to adjust pH and to treat corn for masa and tortillas. It is vegan, gluten-free and kosher, and it adds a little calcium.
Generally safe

Fine for most people at normal amounts.

E-numberE526
Comes fromMineral
What it doesAcidity regulators
Glycemic index—
Daily limitNot set
Also calledE526, Slaked lime

Rules by country

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

Permitted in the US, EU and Canada as a processing aid and pH control agent. Traditional corn treatment with lime is an established food practice.

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

What is it?

Calcium hydroxide is a mineral base. In traditional nixtamalization it loosens corn skins, and it also raises pH in some processing steps. The calcium it leaves behind is a small nutritional bonus.

Where it comes from: Made by heating limestone into quicklime and then adding water. Lime water is used in corn treatment, such as nixtamalization for tortillas.

Why it’s in food

  • Treats corn for masa and tortillas
  • Adds calcium
  • Adjusts pH in processing

Often found in

Corn tortillas and masaSome canned vegetablesSugar refining aids

Also listed as: E526, Slaked lime, Lime water

Health & gut impact

Calcium intakeBenefit

The calcium from food-grade lime is a small but real addition to the diet. It does not replace dairy or leafy greens, but it counts toward daily calcium.

JECFA evaluation of calcium hydroxide

What can I use instead?

Calcium carbonate (E170)

Ratio: A milder base with a similar calcium supply

Best for: Calcium fortification and baking

Sodium hydroxide (E524)

Ratio: A stronger alkali that adds no calcium

Best for: Industrial processing

Related

More acidity regulators:

Acetic acid E260Acetic acid (E260) is the acid that makes vinegar sour. Diluted in food it is considered safe. The hazard is the concentrated factory form, not a splash of vinegar.Generally safeAmmonium carbonate E503Ammonium carbonate (E503) is a traditional leavening agent that makes thin cookies and crackers crisp. It breaks down into gas in the oven, so little of it stays in the finished food.Generally safeCalcium acetate E263Calcium acetate (E263) is a calcium salt of acetic acid that steadies acidity and adds a mild tang in processed foods. It is vegan and gluten-free, and it is also a prescription phosphate binder at much higher doses.Generally safeCalcium carbonate E170Calcium carbonate (E170) is ground limestone, the same calcium found in antacids. It adds calcium to plant milks and flour and is very safe.Generally safe

Common questions

Is calcium hydroxide the same as baking soda?

No. Baking soda is sodium bicarbonate, a mild base for baking. Calcium hydroxide is a stronger mineral base used in corn treatment and processing.

Why is lime used when making tortillas?

It loosens the corn skins and makes niacin and calcium easier to absorb, which is why traditional tortillas are nutritious.

Is Calcium hydroxide safe?

Generally safe (90/100). Permitted in the US, EU and Canada as a processing aid and pH control agent. Traditional corn treatment with lime is an established food practice.

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Scientific sources & regulatory citations
  • EFSA OpenFoodTox: E526
  • JECFA evaluation of calcium hydroxide

INS 526 · CAS 1305-62-0