IDENTIFYING POTENTIAL CHEMICAL MARKERS RESPONSIBLE FOR THE PERMISSIVENESS OF BORDEAUX RED WINES AGAINST BRETTANOMYCES BRUXELLENSIS USING UNTARGETED METABOLOMICS
All along the red winemaking process, many microorganisms develop in wine, some being beneficial and essential, others being feared spoilers. One of the most feared microbial enemy of wine all around the world is Brettanomyces bruxellensis. Indeed, in red wines, this yeast produces volatile phenols, molecules associated with a flavor described as “horse sweat”, “burnt plastic” or “leather”. To produce significant and detectable concentrations of these undesired molecules, the yeasts should first grow and become numerous enough. Even if the genetic group of the strain present and the cellar temperature may modulate the yeast growth rate¹ and thus the risk of spoilage, the main factor seems to be the wines themselves, some being much more permissive to B. bruxellensis development than others. However, common parameters such as pH, alcohol or sugars composition² cannot fully explain the permissiveness differences observed between the wines studied.
The present study aims at identifying (if any) the chemical markers specifically present in permissive wines and absent from resistant ones or conversely. To achieve this goal, the metabolite profiles of red wines coming from different châteaux in Bordeaux area and displaying different permissiveness was examined. The chemical composition was studied using targeted and untargeted metabolic profiling by UHPLC-UV-HRMS and ¹H-NMR. Meanwhile, the wines were inoculated with selected Brettanomyces strains; the microbial growth kinetics were studied and used to classify the wines into distinct groups. With the help of unsupervised statistical analyses, these results were combined in order to draw correlations between the chemical markers and the wine permissiveness.
The nature and the origin of the chemical markers identified is discussed and additional assays are currently performed to confirm the incidence of each marker on the risk of Brettanomyces development.
Issue: OENO Macrowine 2023
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Untargeted metabolomics, Brettanomyces bruxellensis, UHPLC-UV-HRMS, Wine