The geographical traceability of extra virgin olive oils (EVOO) represents an important issue to guarantee the quality and authenticity of this product, which is mainly produced in the Mediterranean area and exported worldwide. For this purpose, we present a geochemical and isotopic study based on the analysis of the REEs content and the 87Sr/86Sr ratio of olives and oils. The REEs content and the 87Sr/86Sr ratio are transferred from the bioavailable soil fraction to the olive pulp, and then to the oil, without any significant elemental and isotopic fractionation, making this method promising for olive oil traceability. The study sites are located in Tuscany, in the Chianti area, High Tiberina Valley, and Maremma with different geological bedrocks and geomorphological settings. Particular attention was paid to minimize local differences in climate, topography, and cultivar. Samples of soils, olives and EVOO were analysed from each olive grove. The main challenges are represented by the low REEs and Sr content in EVOO and by the complex fatty nature of the matrix, so efficient pre-concentration is required to obtain reliable and precise results. To overcome these difficulties, we set up a procedure to extract REEs and Sr from olive oil and olives involving mechanical stirring and ultrasound assisted extraction (Turk et al., 2019), followed by Sr purification using standard chromatographic techniques. 87Sr/86Sr measurements in soil, olives and olive oil were performed by TIMS, while the REEs content was determined by ICP-MS. Preliminary results highlight that the adopted analytical procedure is able to concentrate Sr and REEs from EVOO, allowing precise measurements. Preliminary data on the whole (i.e., independent of the geological bedrocks) dataset show an appreciable variability of the 87Sr/86Sr values among the bioavailable soil portion (0.7079 to 0.7117), olives (0.7081 to 0.7118) and EVOO (0.7085 to 0.7097). The results on the isotope compositions of soil, olives and olive oil will be finally compared with that of the local geology and used to corroborate the traceability method.
Tracing the provenance of Tuscan Extra Virgin Olive Oil using Sr isotopes and Rare Earth Elements.
Ferrari M.;Valeriani L.;Conticelli S.;
2022-01-01
Abstract
The geographical traceability of extra virgin olive oils (EVOO) represents an important issue to guarantee the quality and authenticity of this product, which is mainly produced in the Mediterranean area and exported worldwide. For this purpose, we present a geochemical and isotopic study based on the analysis of the REEs content and the 87Sr/86Sr ratio of olives and oils. The REEs content and the 87Sr/86Sr ratio are transferred from the bioavailable soil fraction to the olive pulp, and then to the oil, without any significant elemental and isotopic fractionation, making this method promising for olive oil traceability. The study sites are located in Tuscany, in the Chianti area, High Tiberina Valley, and Maremma with different geological bedrocks and geomorphological settings. Particular attention was paid to minimize local differences in climate, topography, and cultivar. Samples of soils, olives and EVOO were analysed from each olive grove. The main challenges are represented by the low REEs and Sr content in EVOO and by the complex fatty nature of the matrix, so efficient pre-concentration is required to obtain reliable and precise results. To overcome these difficulties, we set up a procedure to extract REEs and Sr from olive oil and olives involving mechanical stirring and ultrasound assisted extraction (Turk et al., 2019), followed by Sr purification using standard chromatographic techniques. 87Sr/86Sr measurements in soil, olives and olive oil were performed by TIMS, while the REEs content was determined by ICP-MS. Preliminary results highlight that the adopted analytical procedure is able to concentrate Sr and REEs from EVOO, allowing precise measurements. Preliminary data on the whole (i.e., independent of the geological bedrocks) dataset show an appreciable variability of the 87Sr/86Sr values among the bioavailable soil portion (0.7079 to 0.7117), olives (0.7081 to 0.7118) and EVOO (0.7085 to 0.7097). The results on the isotope compositions of soil, olives and olive oil will be finally compared with that of the local geology and used to corroborate the traceability method.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
