If the amount of food allergen present as a contaminant is potentially greater than 1 ppm an ELISA test may be useful. Depending on the production facility and the type of equipment used, testing can be done on environmental swabs or the first product produced after the cleaning has been carried out.

It is recommended that swabbing is carried out on the hang-up areas of the production facility where routine cleaning may not have been completely effective. Where the initial product contains the food allergen in trace amounts i.e. below 1ppm there will be little point in validating the cleaning procedure by testing for the food allergen.

Visual assessment of cleaning will need to be carried out to demonstrate that all reasonable care has been taken to prevent cross-contamination with food allergen containing material.