E522: Aluminium Potassium Sulphate
Main role: firming specified foods
Also listed as: potassium alum, potash alum, aluminum potassium sulfate
What is E522 (Aluminium Potassium Sulphate)?
E522 is potassium alum, a double sulphate salt containing aluminium and potassium. Food-grade material has a specified identity and restricted applications, separate from alum products marketed for other purposes.
What does it do in food?
Its main role is firming specified foods. Mineral ingredients can adjust acidity, firm a food, or keep powders flowing. A technical mineral ingredient does not establish a nutritional dose; use the nutrition declaration to assess amounts per serving.
Food and formulation examples
- Specified fruit preparations
- Limited food firming applications
These examples describe formulation roles, not a list of unrestricted legal uses. Availability and permitted applications differ by country and food category.
Label names and ingredient questions
Look for E522, E 522, or the ingredient name. Related names and label terms include potassium alum, potash alum, aluminum potassium sulfate. A family code can cover more than one specified form; check the full declaration when the distinction matters.
An alum product sold for cosmetics or crafts is not automatically food grade. Confirm the exact ingredient specification and application instead of relying on the common name alum.
Is E522 safe?
EFSA’s 2018 review assessed aluminium sulphates and acidic sodium aluminium phosphate specifically. This is a different assessment from the 2019 review of other phosphate additives. EFSA aluminium-containing additives review (2018).
A label identifies the ingredient but usually not its concentration. Calculating daily intake requires the amount in the food and the quantities eaten.
Authorization and conditions of use
The Great Britain food additive register lists E522 as Aluminium potassium sulphate. This is an entry subject to its stated conditions, not unrestricted permission for every food. The record links to the applicable authorization terms. For an EU product, use the European Commission food additive database to check the relevant food category and limits. Other countries may use different names or rules.