Development and validation of a real-time PCR method for the simultaneous detection of black mustard (Brassica nigra) and brown mustard (Brassica juncea) in food.

The paper presents a real-time PCR method allowing the simultaneous detection of traces of black mustard (Brassica nigra) and brown mustard (Brassica juncea) in food. The primers and the probe target the B. nigra partial RT gene for reverse transcriptase from gypsy-like retroelement 13G42-26. The real-time PCR method does not show any cross-reactivity with other Brassicaceae species with the exception of white mustard. Low cross-reactivities with cinnamon, cumin, fenugreek, ginger, rye and turmeric can be ignored because in common mustard containing foodstuffs these biological species are present in very low amounts. By analysing serially diluted DNA extracts from black and brown mustard, the DNA of both mustard species could be detected down to 0.1 pg. With 10 ng DNA per PCR tube the real-time PCR method allows the detection of 5 ppm black and brown mustard in brewed sausages.