BERT POPPING*, CARMEN DIAZ-AMIGO
Corresponding author*
Eurofins CTC GmbH, Stenzelring 14b, 21107 Hamburg, Germany

Abstract

With most countries having implemented regulations on labelling of allergens in food products, allergen analysis has become a lucrative venture for many laboratories globally. And after all, undeclared allergens are the number one recall reason for food products in the USA, and play a major role in the European Rapid Alert System (RASFF). Laboratories often use commercially available ELISA and PCR assays for convenience. A closer look reveals that not all assays are equal and performance varies significantly depending on matrix and assay used, which ultimately impacts on the reliability of the result. Mass spectrometry, a technology that has already been used for years in pesticide and mycotoxin analysis, has recently also been adopted for allergen analysis and generally shows better sensitivity and higher specificity over existing assays, in particular in processed matrices containing egg, milk or soy, thereby improving the reliability and robustness of results. Assays are, however, only one aspect of the complete method and the way sampling at the factory site is done has a significant impact on how representative a sample and therefore the result obtained by the laboratory is. The manuscript reviews all these aspects and gives examples where methods have shortcomings and how the trueness of the result can be improved.

ANTIBODY BASED TECHNOLOGIES

Antibody-based analysis has been an established technology for many years. Already in the 60s, people used Ouchterlony and Western Blot for the detection of antigens of interest (1, 2). These tools were mainly used in universities rather than contract or enforcement laboratories. While these technologies worked in many cases, they were cumbersome and not very useful for routine applications or high throughput analysis - like it is often demanded these days.
To facilitate easy handling and high volume analyses, many research facilities working with antibodies as diagnostic tools, switched to 96-well microtitre plates. When allergen detection and quantification moved from research facilities into routine food and feed laboratories in the 90ies, commercial ELISA kits (based on the microtitre plates) were produced for convenient handling in the routine laboratory.
The main component of ELISA kits are antibodies and are tested more or less extensively for their specificity, sensitivity and robustness. The assays typically come in one of two formats: plates are coated either with the antibodies (sandwich assay) or ...