The potential of plastid trnL (UAA) intron polymorphisms for the identification of the botanical origin of plant oils

This work describes a methodology for the identification of the botanical origin of plant oils emphasising on the detection of adulteration of olive oil with sesame oil. This methodology comprises a PCR-based assay that exploits the polymorphisms found in the plastid genome combined with a capillary electrophoresis system to discriminate a range of 11 plant species commonly used for oil extraction on the basis of differential length of their corresponding PCR amplicons. The assay takes advantage of universal primers that amplify a region from the trnL (UAA) intron of every plant species. The results showed that amplicons from all species can be accurately discriminated apart from olive and avocado. Single-base primer extension was then proposed as an additional methodology to discriminate the two species and to confirm the results of the former approach. These assays were successfully applied on olive and sesame oils, thus confirming the validity of this approach.