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Absolute quantification of olive oil DNA by droplet digital-PCR (ddPCR): Comparison of isolation and amplification methodologies

Scollo, Francesco, Egea, Leticia A., Gentile, Alessandra, La Malfa, Stefano, Dorado, Gabriel, Hernandez, Pilar
Food chemistry 2016 v.213 pp. 388-394
DNA, cetyltrimethylammonium bromide, nutritive value, olive oil, quantitative polymerase chain reaction, reverse transcriptase polymerase chain reaction, traceability
Olive oil is considered a premium product for its nutritional value and health benefits, and the ability to define its origin and varietal composition is a key step towards ensuring the traceability of the product. However, isolating the DNA from such a matrix is a difficult task. In this study, the quality and quantity of olive oil DNA, isolated using four different DNA isolation protocols, was evaluated using the qRT-PCR and ddPCR techniques. The results indicate that CTAB-based extraction methods were the best for unfiltered oil, while Nucleo Spin-based extraction protocols showed greater overall reproducibility. The use of both qRT-PCR and ddPCR led to the absolute quantification of the DNA copy number. The results clearly demonstrate the importance of the choice of DNA-isolation protocol, which should take into consideration the qualitative aspects of DNA and the evaluation of the amplified DNA copy number.