Performance of ELISA and PCR methods for the determination of allergens in food: an evaluation of six years of proficiency testing for soy (Glycine max L.) and wheat gluten (Triticum aestivum L.).

For the routine detection of allergens in foods, PCR and/or ELISA methods are employed. To assess the suitability of these methods, proficiency tests (PTs) could be used as a valuable instrument. It is a common practice to evaluate the results with respect to the experimentally obtained robust mean without considering the actual allergen content. In the present study, an overview is given of the results of allergen PTs for the determination of soy and gluten conducted by Dienstleistung Lebensmittel Analytik GbR (DLA). A total of 16 PTs were evaluated with respect to the comparison of PCR and ELISA performances and a new focus on the actually spiked values. The analytes were added in the ranges of 7.8-6264 mg/kg (gluten) and 184-5500 mg/kg (soy protein) in differently composed matrices such as pastry, infant food, and sausage meat. The evaluation of the PTs showed a widely reliable qualitative detection of both allergens by PCR methods. ELISA performances differed for soy and gluten. Although a high number of false-negative results occurred for the detection of soy, the qualitative detection of gluten was appropriate. Quantitative results showed obvious test kit-specific differences for the ELISA methods, but the limits of quantification were suitable for gluten determination. Both ELISA and PCR methods demonstrated their valuable contribution in food allergen determination.