Development of a sensitive and user-friendly allele-specific PCR assay for adulteration detection of spices

Spice adulteration not only seriously interferes with their flavoring functions but also leads to life-threatening poisoning for consumers. To overcome the limitations of traditional methods in spice adulteration detection, a multiplex allele-specific PCR system was developed for molecular discrimination of four commonly used spices, Foeniculum vulgare Mill., Zanthoxylum bungeanum Maxim., Illicium verum Hook.f., and Syzygium aromaticum (L.) Merr. & L.M.Perry, from their corresponding adulterants based on chloroplast SNP markers. The developed assay, eliminating the obstacles of DNA sequencing and false negative results, can detect 0.1% of spice adulteration down to 0.01 ng level of genomic DNA with absolute allelic specificity and favorable efficiency. Based on the results, a standard operating procedure for using multiplex allele-specific PCR for spice adulteration detection was established. Therefore, the present study provided a simple, reliable, and sensitive molecular method for adulteration detection of spices.