Development of DNA-based species-specific real-time PCR markers for four berry fruits and their application in commercial berry fruit foods

Berry fruits have attracted attention because of their purported benefits for aging, cardiovascular disease, and cancer. Therefore, highly priced berry fruits might be targets for food adulteration and fraud. In this study, eight species-specific primer sets based on the single nucleotide polymorphism of the chloroplast genomes of four berry fruits (aronia, blackberry, cranberry, and strawberry) were developed for quantitative real-time PCR (qPCR) analysis by SYBR Green staining with the aim of preventing berry fruit food fraud. The developed primer pairs exhibited high efficiencies ranging from 88 to 110% with strong correlation coefficients (R-2>0.99) for the amplification of each target species. However, no clear correlation coefficients were evident for non-target species. To evaluate the practicality of the developed primers, 18 commercial berry fruit products were verified by qPCR analysis. The developed primer pairs were amplified to a low C-t value (range 16.1-23.3) for the target species and proved capable of detecting target species in berry fruit commercial foods. Therefore, the developed qPCR-based species-specific markers could be suitable for the prevention of berry fruit food fraud and to verify marker reliability.