Methods for PDO olive oils traceability: state of art and discussion about the possible contribution of strontium isotopic tool

Olive oil represents an important ingredient in the Mediterranean diet and is appreciated both for nutritional and sensory properties, often related to geographical origin and cultivar of olive fruits employed. Fraudsters trying to seek financial gain can adulterate the product causing economic repercussions and, sometimes sanitary risks. The “protected designation of origin” (PDO) label insures a relative protection of both consumers and honest producers, since it prescribes production techniques and specific geographical origin, but one of the main problems is to set down objective tools to control these specifications. We reviewed numerous studies using various analytical tools to discriminate PDO olive oils’ geographical origin depending on (1) volatiles compounds, (2) fatty acid and triacylglycerol composition, (3) trace elements, and/or (4) stable isotope ratios, but we highlighted that, despite their efficiency, none of them could provide an irrefutable identification. However, ⁸⁷Sr/⁸⁶Sr signature revealed to be an optimal geographical fingerprint in the same purpose for other food products like cereals, orange juice, coffee or alcoholic beverages. Such ⁸⁷Sr/⁸⁶Sr studies do not exist on olive oils, probably because of analytical issues, but we propose that developing complementary ⁸⁷Sr/⁸⁶Sr studies could be a promising tool to re-enforce the characterization of PDO olive oils.