Development and validation of a triplex real-time PCR assay for the simultaneous detection of three mustard species and three celery varieties in food.

The paper presents a triplex real-time PCR assay allowing the simultaneous detection of three mustard species (white, black and brown mustard) and three celery varieties (celery roots, celery stalks and leaf celery) in foodstuffs. The triplex assay does not show cross-reactivity with other Brassicaceae. Low cross-reactivities were observed with fenugreek, cumin, ginger, caraway, turmeric, lovage and rye, the ΔCt values were, however, ⩾ 12 compared to positive controls. The triplex assay allows the detection of traces of DNA of the allergenic components in spite of an excess of the other DNA templates. Analysis of extracts from model sausages containing defined concentrations of mustard and celery showed that the triplex assay is applicable to both raw and processed foods. It was found to allow the detection of 1 ppm black/brown mustard and 50 ppm white mustard and celery in raw and brewed sausages with a probability ⩾ 95%.