Exploitation of the Chloroplast trnL (UAA) Intron Polymorphisms for the Authentication of Plant Oils by Means of a Lab-on-a-Chip Capillary Electrophoresis System

Abstract

Methods to discriminate plant oils facilitate the detection of either deliberate or accidental adulteration. To this direction, the variability in length among plant species of the chloroplast trnL intron was exploited for the authentication of edible and cosmetic plant oils, with an extra emphasis on olive oil. The methodology was based on the combinatorial use of a PCR assay with a capillary electrophoresis system such as the lab-on-a-chip technology. Application of the assay on DNA extracted from different oil producing plant species, including olive oil and sesame oil, indicated the ability of the trnL intron to be used as an analytical target. Furthermore, this assay could be used for the detection of adulteration of olive oil with various other plant oils, with the exception of avocado and sesame oil.

Barcode DNA length polymorphisms vs fatty acid profiling for adulteration detection in olive oil

“…Moreover, barcode size did not vary among the five olive cultivars, providing proof of the species specificity of trnL (UAA) intron length polymorphisms. Our results were in agreement with Spaniolas, Bazakos, Awad, et al (2008), Spaniolas, Bazakos, Spano, et al (2010), who demonstrated length polymorphisms of the barcode amplicon among olive, soybean, sunflower, sesame, cotton, corn and hazelnut. Barcode fragment length polymorphisms among olive and the remaining four oil seed species (palm, rapeseed, peanut and safflower) are shown for the first time in the present research.…”

“…Interspecific length polymorphisms in the plastid trnL (UAA) intron were previously proposed for botanical origin authentication in plant oils (Spaniolas, Bazakos, Awad, et al, 2008;Spaniolas, Bazakos, Spano, et al, 2010). However, the applicability of a barcode amplicon size separation assay to discriminate species-specific fragments in oil blends was not investigated.…”

“…The plastid genome is predominantly used as an analytical target in such work (Ganopoulos, Bazakos, Madesis, Kalaitzis, & Tsaftaris, 2013;Kumar, Kahlon, & Chaudhary, 2011;Li et al, 2012;Spaniolas, Bazakos, Awad, & Kalaitzis, 2008;Spaniolas, Bazakos, Spano, Zoghby, & Kalaitzis, 2010;Vietina et al, 2013;Wu et al, 2011;Zhang et al, 2012), as its high copy number in plant cells enables the recovery of a sufficient quality and quantity of DNA. Moreover, target amplification from a diverse range of taxa is achieved due to the conserved gene order and content of the plastid genome, which allow the design of universal primers (Uncu, Uncu, Celik, Doganlar, & Frary, 2015).…”

“…Moreover, the high rate of insertions/deletions (Gielly & Taberlet, 1994) in the noncoding region can be translated into discriminative amplicon size separation assays that allow the identification of species composition in food products. Spaniolas, Bazakos, Awad, et al (2008), Spaniolas, Bazakos, Spano, et al (2010) were first to describe the potential of the trnL (UAA) intron to authenticate the botanical origin of plant oils. The authors demonstrated the presence of discriminative length polymorphisms in the barcode amplicon among oil crop species.…”

Traceability of Origin and Authenticity of Olive Oil

“…(Consolandi et al, 2008) DNA recovery methods from olive oil have been developed by many authors (Busconi et al 2003;Doveri et al 2006;Pasqualone et al 2007;Consolandi et al 2008). Several commercial kits, providing adapted protocols, were used in different works (Martins-Lopes et al 2008;Spaniolas et al 2008a;Ayed et al 2009;Pafundo et al 2010). All of these studies confirmed that the DNA of the cultivars is recoverable from extra virgin olive oil, but it has low quantity and quality.…”