Oak Barrel Provenance Alters Wine Chemistry

A glass of wine's molecular profile is fine-tuned by variables as widespread as the weather during the grape growing season or the yeast strain that fermented the sugars into ethanol. Now, researchers report that the geographical provenance of oak trees used to make the barrels that hold the fermenting fluid can also leave a lasting imprint on wine's chemistry (Proc. Nat. Acad. Sci. USA, DOI: 10.1073/pnas.0901100106). A team led by physical chemist Régis D. Gougeon of the University of Burgundy, in Dijon, France, and mass spectrometrist Philippe Schmitt-Kopplin of the German Research Center for Environmental Health, in Munich, examined wines from four grape varietals that had been aged in barrels built from oak wood species from nine regions of France. By using mass spectrometry and advanced statistics, the team was able to discern chemical signatures of the different tree species in wines aged in barrels made of them. For instance, in wine aged in barrels made from trees in France's northeast Bitche forests, the scientists observed a signature composed of hundreds of compounds derived from both oak and lichen growing on trees in that region. Examples include metabolites of quercetin, a compound with possible anticancer qualities, and metabolites of the bitter lichen product atranorin.