Conservative Behavior of ⁸⁷Sr/⁸⁶Sr Isotope Ratios from Soil to Olive Oil in Tunisia: A Tool for Geographical Traceability

The measurement of ⁸⁷Sr/⁸⁶Sr isotope ratios is a powerful tool for determining the geographical origin of food products, helping to fight against food fraud. This study evaluates the potential of Sr isotopic ratios for tracing the provenance of Tunisian olive oil. Soil, roots, leaves, olive oil, and pomace were analyzed from multiple orchards across Tunisia. A strong correlation (<i>r</i> = 0.99, <i>p</i> < 0.001) between the ⁸⁷Sr/⁸⁶Sr isotope ratio of olive oil and the paired soil confirms the geological influence. Statistical analysis (ANOVA, <i>p</i> > 0.05) demonstrated that extraction methods for the production of olive oil do not significantly alter the Sr isotopic signature. These findings establish Sr isotope analysis as a robust, processing-independent geographical tracer. By developing a Sr isotope database for Tunisian olive oil, this study provides a scientific framework for authentication, supporting regulatory efforts to prevent mislabeling and protect product integrity in global markets.