Glossary

Processing aid

A processing aid is used while food is made and is not itself an ingredient of the finished product — for example a release agent that is not meant to stay. If an allergen from that process is still present, allergen labelling can still apply. Do not assume “processing aid” means “leave it off”.

Reviewed 23 September 2026 against official guidance.SourcesNot legal advice.

In practice

The FSA technical guidance on allergen labelling explains when a substance used as a processing aid still triggers allergen information. The practical rule in a small kitchen is simpler: if you brush it, mix it or dust it on the food you sell, treat it as an ingredient until a specification shows it is not present.

Egg wash, oil sprays that contain soya lecithin, and wheat flour used to dust a bench and then left on a roll are the cases that cause wrong labels. They are not theoretical processing aids. They are on the product.

Questions

Is egg wash a processing aid?

No. Egg brushed onto pastry is an ingredient of the finished product and must be emphasised.

Can I ignore a release agent?

Only if it is truly not present in the food. If the spray contains soya lecithin and it stays on the traybake, soya is relevant. Check the product.

Official sources

Everything on this page traces back to these. Where they and we disagree, they are right — tell us and we'll fix it.

Introduction to allergen labelling for PPDS foodFood Standards Agency / GOV.UK
Labelling guidance for prepacked for direct sale (PPDS) food productsFood Standards Agency / GOV.UK