PCR-CE-SSCP used to authenticate edible oils

A useful procedure for the qualitative determination of edible vegetable oils adulteration has been developed. A CE-SSCP (Capillary Electrophoresis-Single Strand Conformation Polymorphism) method based on PCR (Polymerase-Chain-Reaction) technology was established to distinguish olive, soybean, sunflower, peanut, sesame, maize and corresponding edible oils, which are the most common edible oils in China. Two rbcL (ribulose 1,5-bisphosphate carboxylase large subunit) gene fragments were amplified from these 6 oil plants by 2 pairs of universal primers (uni4 and rbcl1) respectively and the amplicons were identified by CE-SSCP on ABI 3100 automatic sequence analyzer. Six oil plants were successfully differentiated by combined pattern of uni4 and rbcl1. Sensitivity of the method detecting DNA and oil mixture at different ratio was at level as low as 10% (V/V). The method developed was very suitable for the determination of modeled adulterants but it may also reveal an adulteration even if it does not derive from the adulterants employed in this study.

► Two rbcL gene fragments were amplified from 6 oil plants.
► Six oil plants were differentiated by combined pattern of primers.
► Profiles of DNA extracted from oils were consistent with oil plants.
► Sensitivity detecting DNA and oil mixture was as low as 10%.
► Study of commercial edible oil samples showed that most oils were mislabeled.