Using Rare Earth Elements to Determine the Authenticity and Geographic Origins of Moscato d’Asti Wines

Wine, unlike many other food and beverage products, is somewhat frequently more subject to fraudulent practices that result in significant financial losses for those unknowing victims purchasing what they thought was a high quality wine when in fact it is a fake. It is therefore important to develop ways to test the authenticity of the wine in order to be sure what you’re investing in is real. Similar to the authenticity of a wine is the traceability of wine: is the wine from the geographical location that is indicated on the bottle?

Previous studies have found that lanthanides, the “rare earth elements” on the periodic table between atomic numbers 57 and 71, may be good geochemical markers for determining authenticity and traceability of foods, and have been shown to determine origins of several foodstuffs, including hazelnuts. Many

studies have shown that there is good traceability using lanthanides up until the must stage, as the lanthanide profile remains fairly constant throughout the growing season and through harvest. However, since wine undergoes many chemical changes during the winemaking process, using lanthanides may actually be problematic for determining authenticity and traceability, as it’s been shown that using bentonite during the clarification process changes the lanthanide profile in wine, thereby making authenticity determinations a lot more difficult. To date, it has not been made clear how the winemaking process alters the lanthanide fraction of wine, and if this alteration results in problems with testing authenticity or traceability of those wines or not.

The study presented today aimed to add to the literature on using lanthanide signatures to determine authenticity and traceability using Moscato d’Asti wine, and to determine if the winemaking process results in the alteration of this lanthanide profile and whether or not this method is appropriate for catching fraudulent wines or determining authenticity and traceability in general for wine.

Methods

For determining the traceability from soil to must; soils, grapes, and musts were collected from the experimental vineyard of Centro Sperimentale Vitivinicolo Tenuta La Cannona in Carpeneto, AL, Italy. For determining authenticity of Moscato d’Asti musts and wines, samples were collected from various producers throughout the Piedmont region of Italy. All must samples were frozen prior to testing, and thawed 4 hours prior to analysis.

Elemental analysis was performed on soil, grape, and must samples, focusing primarily on the rare earth elements/lanthanides. These analyses were performed on a X5 Series inductively coupled plasma mass spectrometer.

Results

• The rare earth element profile including lanthanides was nearly identical from soil to grape to must for Moscato d’Asti.
• Cerium (140Ce) was found to be most abundant in all samples tested.
• Filtering the musts with amorphous silica diatomites (rectification step in winemaking) resulted in a marked change in the rare earth element profiles, as the profile in filtered samples were found to be drastically different than the profile of the original must samples.
o The most significant changes were noted for the elements 175Lu and 172Yb (Lutetium and Ytterbium, respectively).
• The clarification of the musts using Bentonite provided an even more drastic change in the rare earth element profile compared with the must sample after the filtering step and the original must.
o This may be attributed to the fact that Bentonite releases metal ions into the must during the clarification process, thus significantly altering the rare earth element profile of that must.
o Therefore, it is not possible to use the rare earth element profile of wine to determine the traceability of the wine, since this profile is so drastically altered during the bentonite treatment in the clarification step of winemaking. If an alternative to bentonite that did not release metal ions into the must was used, then perhaps this method of analyzing the rare earth element profile to measure traceability would be useful.
o Traceability is completely possible and very accurate from the soils to the musts, but not after the winemaking process using bentonite.
• Principal components analysis (PCA) showed a clear separation in rare earth elements of Italian wines between geographical locations, though some of the separations were narrow.
o This result indicates that it is possible to determine if a particular wine is from a particular geographic location or not.

Conclusions

I found it fascinating that one can trace a must back to the location where the grapes grew in the soil, simply by measuring the profile of rare earth elements in the must, grapes, and soil. Those rare earth elements that are in the soil of a particular area are taken up by the grapevine and transported via the xylem and phoelm into the grape berries without altering the profile from soil to grape. It makes me wonder if this is evidence of terroir—the rare earth element profile appears to be different for every geographical location, as evident in the PCA analysis during the authenticity portion of this study, so perhaps this is the sort of scientific evidence needed to “prove” the existence of terroir. That’s just a thought, but I think it’s a good starting point.

After the musts are chemically altered by the winemaking process, particularly after the clarification by bentonite stage, the rare earth element profile no longer represents the profile of the original must nor does it represent the profile of the grapes and soil from which the wine came. This makes sense to me,

as if you’re going to add any chemical you’re likely going to alter the chemical make-up of that wine due to chemical reactions that may take place. The authors suggested that wine that is not treated with bentonite may show similar rare earth element profiles to the original profiles, though I am not convinced. There are other chemicals added to wine during the winemaking process, and I’m not yet convinced that those chemicals might not interact and alter the rare earth element profile of the finished wine. I’d like to see a follow up study examining this issue.

Overall, I thought this was a really neat study, despite the fact that it was relatively short and was lacking some treatments that I would have liked to see (i.e. different stages during the winemaking process). I would love to see a follow up to this study perhaps taking it in the direction of scientifically showing the existence of terroir, and also perhaps a follow up looking at grapes in other parts of the world.

I’d love to hear what you all think of this topic! Please feel free to leave your comments!

Source: Aceto, M., Robotti, E., Oddone, M., Baldizzone, M., Bonifacino, G., Bezzo, G., Di Stefano, R., Gosetti, F., Mazzucco, E., Manfredi, M., Marengo, E. 2013. A traceability study on the Moscato wine chain. Food Chemistry 138: 1914-1922.