Applicability of quantitative polymerase chain reaction (qPCR) assays for common bean authentication in processed food

Food authentication by quantitative polymerase chain reaction (qPCR) methods assures food quality. The aim was to evaluate three qPCR assays for DNA quantification after heat processing of common bean grains, genus-specific FAS assay for Phaseolus, species-specific LEC assay for common bean (Phaseolus vulgaris) and genetically modified (GM) event-specific FGM assay for Embrapa 5.1 event GM common bean. FAS assay showed high stability among Phaseolus genus samples. Common bean grains were heat-treated in autoclave (at 120 degrees C for 15-60 min) and target DNA copy number decreased as processing time increased. Even with DNA degradation, qPCR assays were capable to detect low DNA quantity, and the limit of detection was 100 copy number. Mean efficiency value of FGM assay was 92% in the presence of background DNA. Background DNA did not cause any interference, and 0.39% of GM material can be detected. These qPCR assays are able to quantify common bean in processed food.