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.

Stability of bovine allergens during food processing.

OBJECTIVE: The primary objective of this review was to summarize reported findings about the influence of various food manufacturing processes on the potential alteration of bovine allergens in cow's milk, beef, and related food products. DATA SOURCES: This review was based on literature research in two German databases. STUDY SELECTION: The expert opinion of the authors was used to select the relevant data for the review. RESULTS: Changes in allergenic activity during food processing are attributable to inactivation or destruction of epitope structures, formation of new epitopes, or improved access of previously hidden epitopes. The allergenic potency of food could be altered by several food manufacturing procedures--such as mechanical, purification, thermal, biochemical, and chemical processes. The main processing steps studied by investigators were heating (dry heating, boiling, or cooking) and enzymatic digestion. A review of the available literature on the alteration of bovine allergens in cow's milk, meat, and related food products revealed reduction (but not elimination) of allergenicity by heating of cow's milk for 10 minutes. Although homogenization did not change the allergenic potency of cow's milk, it decreased the allergenicity of beef, as did freeze-drying. Digestion studies showed varied results. CONCLUSIONS: The allergenicity of some food products decreased during certain processing steps, but the results of other investigations differed. Therefore, more systematic research on the influence of food processing on allergenicity should be undertaken.