E522 · Firming agents

Aluminium potassium sulphate

High risk

Best avoided due to neurotoxicity concerns associated with high aluminum intake.

Category: Firming agents
Vegan: Yes
Vegetarian: Yes

What it is

Aluminium potassium sulphate — potash alum — is a light-metal salt used as a firming agent and stabiliser.

How it is used in food

Firms pickled vegetables and stabilises colour.

Commonly found in

Pickled vegetables (historical)
Candied fruits

Health and safety

As with the other aluminium salts, the issue is cumulative exposure rather than acute toxicity: aluminium builds up in bone and tissue and is cleared slowly, against an EFSA tolerable weekly intake of 1 mg per kg of body weight that some diets already meet.

Can contribute to excessive dietary aluminum load if consumed frequently.

Aluminium Accumulation

General population · evidence: suspected

Aluminium from food additives can accumulate in the body over time, which has been controversially linked to neurological conditions.

Authorised in the EU, with permitted uses cut back in 2012 to reduce total dietary aluminium. EFSA's tolerable weekly intake is 1 mg/kg body weight.

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: E522

Also printed asAluminium potassium sulfate · aluminum potassium sulfate · aluminum potassium sulphate

Worth knowing

Potash alum is the classic alum of the pickle crock, used to keep cucumbers crisp long before its aluminium content was a talking point.

Conclusion

Best avoided due to neurotoxicity concerns associated with high aluminum intake.

References

EFSA Safety Assessment

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Entry last reviewed 2026-07-28.

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