Development of a Real-Time PCR Approach for the Specific Detection of <i>Prunus mahaleb</i>

Abstract

In 2015 a number of cumin spice products were withdrawn from the international market because of the suspected presence of almond, a known allergen from the Prunus genus. However, immunoassay results were unable to provide unequivocal evidence of the Prunus species present, because of significant cross-reactivity with other species within the Prunus genus. A novel real-time PCR assay was developed for the specific detection of Prunus mahaleb DNA, a species known to be capable of causing false positives in almond immunoassays. The assay was developed based on available DNA sequence information from the Internal Transcribed Spacer (ITS) region, and tested against representative species within the Prunus genus to ensure no cross-reactivity. Results showed that mahaleb DNA was detected in a cumin spice product subject to the earlier international recalls, which could not be unequivocally identified using immunoassay approaches alone. This short report details preliminary results from the application of this assay, and will be of interest to analytical laboratories involved in trace detection of ingredients in support of relevant food labelling legislation.