E529

Calcium oxide

No known risk

Quicklime, processing aid.

Vegan: Yes
Vegetarian: Yes

What it is

A strong alkaline base used to rapidly raise pH, peel fruits, or alter the surface texture of baked goods.

How it is used in food

Used as a dough conditioner and acidity regulator, often converting to calcium hydroxide (E526) upon contact with water.

Commonly found in

Pretzels
Bagels
Canned olives
Cocoa processing

Health and safety

None in the finished food. It reacts with water almost immediately to become calcium hydroxide, and is neutralised from there.

Permitted as a processing aid; it does not persist as quicklime in food.

Regulatory status

Region	Status	Notes
Australia & New Zealand FSANZ	Permitted	Permitted under the FSANZ Food Standards Code.
European Union EFSA / European Commission	Permitted	Authorised for food use under EU regulations (Annex II).
United States FDA (Food and Drug Administration)	Permitted	Authorised for food use by the FDA (often GRAS for standard additives).

Identification on labels

E-number: E529

How it is made

Synthesized industrially from basic mineral and chemical feedstocks.

Calcination — Limestone (calcium carbonate) is heated to very high temperatures (around 900°C) to drive off carbon dioxide, leaving behind calcium oxide.

Worth knowing

Commonly known as 'quicklime', it reacts violently with water to produce extreme heat.

Conclusion

There is no reason to avoid calcium oxide in your food. It converts almost instantly upon contact with water into calcium hydroxide before being fully neutralised during dough conditioning or food preparation. EFSA permits it as a safe processing aid that does not remain as quicklime in the finished product.

References

INCHEM JECFA Evaluation

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Entry last reviewed 2026-07-28.

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