DNA analysis is rarely used for the verification of edible oil species, because of the low amount of intact DNA in the refined oil and the genetic similarities between different oil varieties. In this study (open access pre-print, not yet peer-reviewed) the authors compared different DNA extraction kits and PCR protocols and new genetic markers to try and resolve the issue. They reported that DNA extraction kits such as NucleoSpin Food, DNeasy mericon Food, and Olive Oil DNA Isolation as well as modified CTAB method were found to be able to isolate amplifiable genomic DNA from highly processed oils. Novel uniplex, double, and nested PCR systems targeting the sunflower-specific helianthinin gene were developed for efficient identification of sunflower. New sunflower DNA markers were revealed by uniplex PCRs.
They concluded that a combination of modified CTAB and nested PCR gave the best performance, and was demonstrated as a reliable, rapid, and cost-effective technology for detecting traces of sunflower in highly processed oil, including refined and used cooking oil.
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