The Extra Virgin Olive Oil (EVOO) is a primary and important component of our diet, therefore the provision of methods that testify its quality and authenticity represents an essential issue. The use of petrochemical parameters represents one the most promising approach to trace the geographical provenance of this precious product. Pelacani et al. (2017) and Techer et al. (2017) showed that the REEs and the 87Sr/86Sr signatures are transferred from the bioavailable soil fraction (BSF) to the olive pulp, and then to the oil, without any significant elemental and isotopic fractionation. In this work, we therefore present a geochemical and isotopic study dealing with the REEs content and 87Sr/86Sr ratio of EVOOs and related olives, with the aim to establish a method for EVOO traceability. Samples of bioavailable soil fraction, olive, and oil were collected from Tuscan olive groves from the Chianti area, High Tiberina Valley, and Maremma. The selected localities are characterized by different geological and geomorphological settings, with minimal differences in climate, topography, and cultivar. Contrary to BSFs and olives, oils are characterized by low REEs and Sr content, which represents the main challenge in determining their elemental and isotopic content. Therefore, 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 ultrasoundassisted 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 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 EVOOs (0.7085 to 0.7097). In addition, oils from different foreign countries were compared to verify any possible isotopic and compositional differences with Tuscan EVOO.
Sr isotopes and Rare Earth Elements as tracing tools: the Tuscan Extra Virgin Olive Oil case study / Ghiotto M., Ferrari M., Valeriani L., Bragagni A., Pucci C., Malpaganti A., Casalini M., Pelacani S., Conticelli S., Riccio R., Moretti S., Tommasini S.. - ELETTRONICO. - (2023), pp. 773-773. (Intervento presentato al convegno The Geoscience paradigm: resources, risks and future perspectives tenutosi a Potenza nel 19-21 settembre 2023).
Sr isotopes and Rare Earth Elements as tracing tools: the Tuscan Extra Virgin Olive Oil case study
Ghiotto M.;Ferrari M.;Casalini M.;Pelacani S.;Conticelli S.;Moretti S.;Tommasini S.
2023
Abstract
The Extra Virgin Olive Oil (EVOO) is a primary and important component of our diet, therefore the provision of methods that testify its quality and authenticity represents an essential issue. The use of petrochemical parameters represents one the most promising approach to trace the geographical provenance of this precious product. Pelacani et al. (2017) and Techer et al. (2017) showed that the REEs and the 87Sr/86Sr signatures are transferred from the bioavailable soil fraction (BSF) to the olive pulp, and then to the oil, without any significant elemental and isotopic fractionation. In this work, we therefore present a geochemical and isotopic study dealing with the REEs content and 87Sr/86Sr ratio of EVOOs and related olives, with the aim to establish a method for EVOO traceability. Samples of bioavailable soil fraction, olive, and oil were collected from Tuscan olive groves from the Chianti area, High Tiberina Valley, and Maremma. The selected localities are characterized by different geological and geomorphological settings, with minimal differences in climate, topography, and cultivar. Contrary to BSFs and olives, oils are characterized by low REEs and Sr content, which represents the main challenge in determining their elemental and isotopic content. Therefore, 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 ultrasoundassisted 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 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 EVOOs (0.7085 to 0.7097). In addition, oils from different foreign countries were compared to verify any possible isotopic and compositional differences with Tuscan EVOO.
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