An analytical approach to Sr isotope ratio determination in Lambrusco wines for geographical traceability purposes

Abstract

Geographical origin and authenticity of food are topics of interest for both consumers and producers. Among the different indicators used for traceability studies, 87Sr/86Sr isotopic ratio has provided excellent results. In this study, two analytical approaches for wine sample pre-treatment, microwave and low temperature mineralisation, were investigated to develop accurate and precise analytical method for 87Sr/86Sr determination. The two procedures led to comparable results (paired t-test, with t<tcrit). Furthermore, the precision of the whole analytical procedure was evaluated by using a control sample (wine sample), processed during each sample batch (calculated Relative Standard Deviation, RSD%, equal to 0.002%. Lambrusco PDO (Protected Designation of Origin) wines coming from four different vintages (2009, 2010, 2011 and 2012) were pre-treated according to the best procedure and their isotopic values were compared with isotopic data coming from (i) soils of their territory of origin and (ii) wines obtained by same grape varieties cultivated in different districts. The obtained results have shown no significant variability among the different vintages of wines and a perfect agreement between the isotopic range of the soils and wines has been observed. Nevertheless, the investigated indicator was not enough powerful to discriminate between similar products. To this regard, it is worth to note that more soil samples as well as wines coming from different districts will be considered to obtain more trustworthy results.