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E525AcidulantLow concern
Potassium Hydroxide
In plain words
The short version
Caustic potash — sodium-free alkali for pretzel browning, olive curing, and Dutch cocoa.
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
ADI not specified — neutralized to harmless potassium salts during food processing. Pure material is highly corrosive (workplace hazard) but the consumer-product residual is trace.
The detail
Manufactured industrially by electrolysis of potassium chloride brine. Food-grade material meets strict heavy-metal purity criteria.
The sodium-free alternative to NaOH (E524) — used in low-sodium pretzel and bagel browning, lye-cured olives, Dutch-process cocoa, infant formula pH adjustment, and some Asian noodles. Functions as a pH adjuster at low residual levels.
White solid (pellets or flakes), strongly hygroscopic and deliquescent. Dissolves exothermically in water. Strong base (pH 14 in 1 M solution).
Permitted globally as a processing aid and pH regulator. Residual must be neutralized in the finished product.
Sources
- JECFA database — Potassium hydroxide (INS 525), evaluation 1965 (9th meeting) — WHO / Joint FAO/WHO Expert Committee on Food Additives, 1965. Safety: ADI not limited (older term equivalent to 'not specified')
- 21 CFR 184.1631 — Potassium hydroxide (affirmed GRAS) — eCFR / US FDA, 2026. US status: GRAS, no limitation other than GMP (pH control, processing aid, formulation aid, stabilizer)
- Regulation (EC) No 1333/2008 on food additives — consolidated text of 18.08.2026 (Annex II) — EUR-Lex / European Union, 2026. EU status: Group I additive at quantum satis; also pH adjustment in baby foods
Checked against these sources on .
Educational information only. Not medical, dietary or veterinary advice. Spotted an error? Tell us.