Combined use of 87Sr/86Sr and carbon isotopes with multielemental analysis for the geographical authentication of Tunisian and European olive oils.

The geographical authentication in the agrifood industry has become a major issue to guarantee the quality of food products. Olive oil (OO) is particularly a complex matrix and establishing a reliable approach for linking OO samples to their origin is an analytical challenge. In this study, the isotopic composition of carbon, strontium and the concentrations of seventeen elements were determined in OOs from Tunisia, Southern France and the South Basque country. The preliminary results overlapped and showed that, taken individually, the isotopic and elemental approaches were not discriminant. A linear discriminant analysis applied to δ13C, 87Sr/86Sr and to the concentrations of 4 selected trace elements (Fe, Mn, V and Cr) allowed to classify, with high resolution, olive oils into 3 groups according to their provenance. The combination of the plant growing environment, the geological background, the mineral composition of the soil and the production process lead to a novel approach to deal with fraudulent practices in OO sector.