LFDs and swab tests are highly specific and based upon antibodies that bind to protein(s) from the allergenic food. These test methods are qualitative but capable of detecting very low residual levels of allergens on equipment surfaces. These methods can also be used for detection of residues in clean-in-place (CIP) final rinse water samples. Some companies use these qualitative methods on ingredients or processed food samples, but their use for such purposes is not recommended unless careful evaluations have been done to ensure that the food matrix does not interfere with the detection of residues using LFDs.
Because food allergens are proteins, allergen-specific swabs and LFDs are the most relevant approach to determine if allergen residues remain on equipment surfaces. However, other swab approaches are available, including general protein tests (e.g., 3M Clean-Trace) and ATP tests (e.g., Charm AllerGiene). General protein tests detect protein residues from any source, allergen or not. ATP is a molecule found in all biological organisms, so ATP testing will detect soil residues on equipment surfaces from many sources. In our experience, general protein and ATP swab methods are slightly less sensitive than allergen-specific LFD methods. Due to their specificity, allergen-specific swabs with LFDs are more suitable for validation of SSOP effectiveness.
Deciding on a Testing System
Careful thought should be given to selection of the optimal commercial kit. The following are some tips on choosing the correct test to help ensure allergen SSOPs are as effective as possible.