Identification of Small Berry Species in Food and Juice Using TaqMan-Based Real-Time PCR

Background: Public interest is growing for small berries in recent years because they are very delicious, low in energy, and full of bioactive compounds with potential health benefits. Similar to other food products, adulteration of small berry fruit products poses economic and safety problems to consumers. Objective: To protect consumers and regulate the small berry fruit products market, it is necessary to establish a robust method for detecting the authenticity. Methods: In this study, TaqMan-based real-time PCR assay was established for species identification of cranberry, raspberry, and blueberry to ensure authenticity of commercial small berry food products (pulp, dried fruit, fruit juice, jam, and puree). Results: Absolute detection limit was 0.1 pg/μL DNA for raspberries, 1 pg/μL DNA for blueberries, and 10 pg/μL DNA for cranberries. Practical LOD was 0.1% (v/v) for fresh juice. For processed juice, practical LOD was 1% for blueberry and red raspberries, 0.1% for black and yellow raspberries, and 5% for cranberry. Conclusions: The method was shown to be functional and effective to detect the raw material composition of cranberry, raspberry, and blueberry for commercial products. Highlights: TaqMan probe-based real-time PCR methods were designed to identify three small berries (blueberry, raspberry, and cranberry) in berry products. Efficient DNA recovery methods and detection strategy were established to ensure correct and sensitive testing of fresh small berries exhibited a detection limit of 0.1 to 10 pg/μL. The practical minimum detection levels were 0.1 to 5% in fresh and processed juice, including pasteurization and HTHP.