Abstract

Detection of Food Allergens in Processed Foods – An Overview and Comparison of Current Methods

Martin Roder, Food Chemist, Head of Food Allergens, Institute For Product Quality

In contrast to other analytical methods the analysis of food allergens is currently linked with quite high measurement uncertainties, especially in unknown samples. Decisive is that the analysis is not based on the detection of a single or few stable molecules, like e.g. pesticide analysis, but on natural organic macromolecules: proteins and deoxyribonucleic acid (DNA). The amount and/or structure of both molecules may vary between species and both are prone to degradation during food processing and /or may be affected by the matrix itself. Therefore, each method that is based on the analysis of either DNA or protein will be more or less affected by these issues. The first methods that have been developed for food allergen detection were based on antibodies. The Enzyme-Linked Immuno-Sorbent Assay (ELISA) was firstly introduced in the 1990s and is still the most common format. Allergen specific antibodies detect the target allergen protein by binding to certain structures (epitopes).The visualization of the binding is based on a colorimetric change caused by enzyme-linked conjugates that can be measured photometrically. For most of the allergenic foods, ELISA test kits are commercially available. The common use of ELISA is due to the easy handling, rapidness, and sensitivity. Lateral flow devices (LFD) are another antibody based possibility to detect allergenic foods in food. These rapid tests give results within minutes. The format is especially applied in food industry, e.g. for cleaning verification, since it can be done without any further equipment.  The sensitivity is approximately in the same range as the ELISA and gives results in the low mg/kg range. One major drawback of antibody based methods is that these tests may have a limited specificity. This means, antibodies may also bind to proteins from other foods, especially if structures (epitopes) are detected that are present in conserved protein families. False negative results may occur if the used