FLAVANOL COMPOSITION OF VARIETAL AND BLEND WINES MADE BEFORE AND AFTER FERMENTATION FROM SYRAH, MARSELAN AND TANNAT

Abstract

Background: The Flavan-3-ol extraction from grape skin and seed during red-winemaking and their retention into wines depend on many factors, some of which are modified in the winemaking of blend wines. Recent research shows that Marselan, have grapes with high proportion of skins with high concentrations of flavanols, but produces red-wines with low proportion of skin derived flavanols, differently to the observed in Syrah or Tannat. But the factors explaining these differences are not yet understood. Thus, the aim of this work was to evaluate if factors cited to affect tannin extraction and solubility, like solid to liquid ratio, anthocyanin concentration, seed to skin proportion, are behind the differences found in the flavanol composition of Syrah, Marselan and Tannat wines. Material and Methods: Over two vintages, 2019 and 2020, wines were made by the blending of grape-must before-fermentation (BFB) or of wines, after-fermentation (AFB), in proportion of 1/2-1/2 of Tannat-Marselan, Tannat-Syrah, Syrah-Marselan, and 1/3-1/3-1/3 of Tannat-Syrah-Marselan. The varietal wines (VW) were elaborated as well. All treatments were vinified by triplicate at experimental scale. Grape samples were taken before each winemaking. Macerations along 8 days were made in all cases. Spectrophotometric analysis were performed together with HPLC-ESI-Q-ToF determinations of flavan-3-ols. The wine to skin prodelphinidins quotient was used to estimate skin contribution to the wine flavanols. Results: In all cases, the flavanol structural composition of the grapes and of the varietal wines corresponded to the one expected for cultivar it belongs to. Thus, the results confirmed that under traditional red-winemaking, the flavanol composition of Syrah and Tannat wines mainly depends on the Skins while in Marselan mainly on seeds. The blend wines had a flavanol content and structural composition that closely matched the one that could be expected considering the composition of the varietal wines and the proportion of each cultivar in the blend. Therefore, there was also no significant effect of the time of blend (BFB vs AFB) on the flavanol concentration or composition of the wines. Conclusion: None of the factors that were modified in the winemaking of blend wines were behind the differences observed in the flavanol composition of the varietal wines of Syrah, Marselan and Tannat. Ongoing studies in Marselan may help to better understand the flavanol composition of wines.

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