Applicability of Qualitative Real-Time PCR Methods for Detecting Wheat, Buckwheat, and Peanut in Processed Food

Abstract

In Japan, it is mandatory that processed foods containing specific allergenic ingredients be clearly labeled as such. Previously, we developed qualitative real-time PCR methods that enable sensitive and specific detection of wheat, buckwheat, and peanut in foods. The results of interlaboratory validation showed that the performance of these methods meets the criteria of the official Japanese government guidelines. In this study, we evaluated the applicability of qualitative real-time PCR as a confirmation test after an ELISA screening test using 60 samples of commercially available processed foods. The results indicated that the qualitative real-time PCR could detect wheat, buckwheat, and peanut in various foods containing allergens with ELISA values of 10 ppm or higher. Next, we evaluated whether the qualitative real-time PCR could be applied as a primary qualitative test that is faster and less likely to miss the target allergens. To do so, we combined it with a simple DNA extraction kit to utilize this method in a different workflow from the official method. As a result, the identical samples that were positive in the workflow from the official method were judged to be positive for the target allergen. In addition, since it was possible to detect samples with an ELISA value of less than 10 ppm, this study suggests that the qualitative real-time PCR has sufficient sensitivity to be used as a primary qualitative test.