A comparative 87Sr/86Sr study in Red and White wines to validate its use as geochemical tracer for the geographical origin of wine

Recently high precision 87Sr/86Sr analyses have shown that Red wines keep the isotopic values of the vineyard substratum. Indeed, neither biological nor winemaking and aging processes are able to change the 87Sr/86Sr values through the oenological food chain from grapes to Red wine. In addition, 87Sr/86Sr of Red wines and those of rocks from the geological substratum of their vineyards correlate directly. The same holds not true for White wines, apparently. To investigate this discrepancy, 87Sr/86Sr has been determined for the entire production chain, from terroir to final product, of Red and White wines from the same vineyard. Sr-isotope data have been also determined for the young pyroclastic rocks of the geological substratum, and the soil of the vineyard to disambiguate the original contribution to the 87Sr/86Sr values of wines. Further Sr-isotope data have been determined on additives used for fining the White wine. The analytical results do not show significant differences between oenological food chains of Red and White wines. Preliminary data indicate that 87Sr/86Sr does not change passing from grape juices to wine in all cases under consideration. As a corollary neither yeast nor bentonite added during vinification of both Red and White wines do affect their Sr-isotopic values. On the other hand, 87Sr/86Sr of Red and White wines appears to be significantly lower than values observed in rocks of their substrata. Further experiments performed on this pilot winery would be useful to shed some lights on this issue.