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E526AcidulantLow concern
Calcium Hydroxide
In plain words
The short version
Slaked lime — the alkali of corn nixtamalization, tofu coagulation, and traditional pickling.
Why it's green
It's widely considered safe at the amounts used in food, so we mark it green. The Safety section below has the details.
Safety profile
JECFA ADI 'not limited' (1965) — considered safe at the levels used in food. The active material is corrosive in pure form, but is fully neutralized during processing.
The detail
Produced by hydration of calcium oxide (quicklime), itself from thermal decomposition of limestone. Among the oldest deliberately used chemicals — Mesoamerican civilizations used it for corn nixtamalization for at least 3500 years.
The alkali of nixtamalization — soaking corn in calcium-hydroxide-treated water before grinding releases bound niacin, transforms aromatics, and produces the distinctive tortilla/masa flavor and aroma. Also coagulates soft tofu, firms pickled vegetables (cucumber and watermelon-rind pickles), and clarifies sugar in cane-juice processing.
White powder, sparingly soluble in water (limewater). Strongly alkaline solution. Reacts exothermically with acids.
Permitted globally without restrictive limits as a processing aid and acidity regulator.
Sources
- WHO JECFA database: Calcium hydroxide (INS 526), ADI not limited (9th meeting, 1965) — WHO / FAO Joint Expert Committee on Food Additives, 1965. JECFA safety evaluation (ADI category)
- US eCFR: 21 CFR 184.1205 Calcium hydroxide (GRAS) — US Office of the Federal Register / FDA, 2026. US status: no limitation other than GMP
- EU: Commission Regulation (EU) No 1129/2011 establishing the Union list of food additives (Annex II to Reg. 1333/2008), as adopted — European Union (Publications Office), 2011. EU authorisation at quantum satis
Checked against these sources on .
Educational information only. Not medical, dietary or veterinary advice. Spotted an error? Tell us.