Characterisation and attempted differentiation of European and extra-European olive oils using stable isotope ratio analysis.

European law requires a designation of origin for virgin and extra virgin olive oils (at least in terms of EU/non-EU provenance). Stable isotope ratios have been successfully applied to determine the geographical origin of olive oils, but never to distinguish EU and non-EU oils. In this study 2H/1H, 13C/12C and 18O/16O ratios were analysed in bulk olive oils using Isotope Ratio Mass Spectrometry (IRMS) as well as 13C/12C and 2H/1H in the four main fatty acids (linoleic, oleic, palmitic and stearic acids) using IRMS coupled with GC. The isotopic composition of olive oils was successfully used to distinguish samples originating in the two areas. Specifically, when bulk data were combined with fatty acid isotopic data the differentiation power of the method improved clearly. This separation is due to the specific isotopic fingerprint of the individual countries making up the EU and non-EU samples.