Effect of the vintage year on strontium isotopic ratio (<sup>87</sup>Sr/<sup>86</sup>Sr) of wines: a Portuguese case study.

Abstract

<h4>Background</h4>Currently, there is a growing need for wine authenticity tools to face the global wine market and deal with adulteration cases. Stable isotope analyses, recognized by the Organization of Vine and Wine as a tool for detecting authenticity fraud, form the basis of the European Wine Databank, which faces limitations concerning the geographical origin of wines. Several studies were developed on applying the ⁸⁷Sr/⁸⁶Sr isotopic ratio to evaluate wine geographical origin, involving wine-producing regions worldwide. The most important feature of Sr, evidencing its reliability as a provenance tracer, is its assimilation by the vine plant roots in the same isotopic proportions in which they occur. Although important aspects such as ⁸⁷Sr/⁸⁶Sr in relation to the vineyard substratum, analytical methodologies and the effect of technological processes have been addressed, relevant issues remain, such as the interpretation of soil data and the need for a better understanding of the impacts of anthropogenic factors. In this context, the strontium isotope ratio of Arinto (Vitis vinifera L.) wine samples from the same vineyard located in the Lisbon wine region, across 13 vintages, was assessed.<h4>Results</h4>Before ⁸⁷Sr/⁸⁶Sr determination by quadrupole inductively coupled plasma mass spectrometer, the samples underwent a pretreatment procedure: (i) sample digestion by high-pressure microwave digestion for the elimination of organic substances to prevent any interference during chromatographic separation, and (ii) chromatographic separation of ⁸⁷Sr and ⁸⁷Rb to avoid isobaric overlapping ⁸⁷Rb and ⁸⁷Sr. The values of ⁸⁷Sr/⁸⁶Sr found in the studied wines, ranging between 0.706 and 0.709, are consistent with those reported for soils developed on different basaltic rocks.<h4>Conclusion</h4>No significant differences were observed between the isotopic ratio values of the wines from different vintages, thus confirming the reliability of this isotopic ratio for traceability purposes. © 2025 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.