Authentication and traceability of Italian extra-virgin olive oils by means of stable isotopes techniques

Authentication of food origin is relevant to avoid food fraud. This work aimed to explore the variation of isotopic compositions (δ13C, δ18O) of extra-virgin olive oils from Italy growing in different environmental conditions. A total of 387 oil samples from nine different regions (from North to South), produced on 2009, 2010 and 2011, were analysed. Statistical analysis showed correlations among oil isotope compositions and latitude, mean annual temperature, mean annual precipitation and xerothermic index. No correlation was found comparing isotope compositions with elevation and longitude. An observed shift of the oil δ18O per centigrade degree of the mean annual temperature is congruent with literature. The year effect was significant for both δ18O and δ13C. Samples from Sicilia and Sardegna were higher in 13C and 18O than oils from northern regions.