INFLUENCE OF GRAPE RIPENESS ON MACROMOLECULES EXTRACTABILITY FROM GRAPE SKIN TISSUES AND GRAPE SEEDS DURING WINEMAKING
A consequence of climate change is the modification of grape harvest quality and physico-chemical parameters of the obtained wine: increase in alcoholic degree, decrease in pH, and modification of the extractability of macromolecules, which leads to problems of microbiological, tartaric, colour and colloidal stability. In order to respond to these problems, the winemaking processes must be anticipated and adapted with a better knowledge of macromolecule extractability in grapes and their evolution, according to the grape variety, vintage and winemaking process. The purpose of this study was to understand 1) how the harvest date can influence the extractability of macromolecules, polysaccharides and phenolic compounds, which are responsible for wine stability 2) how to adapt the winemaking process to the harvest date in order to optimise wine quality.
In this study, the extraction of grape seeds and grape skins macromolecules in wine has been investigated during the 2020 and the 2021 vintage at different grape maturity stages. At each maturity stage, three winemaking modalities have been produced: (i) a control modality (whole berry), (ii) a grape seeds modality made of exclusively with seed and (iii) a grape skins modality made of exclusively with skins. The evolution of skin, seed and wine macromolecules content (such as polysaccharides and phenolic compounds) has been followed during the winemaking, from alcoholic fermentation to post-fermentative maceration.
The findings have shown that grape berry ripeness influences the extractability levels, types and kinetics of macromolecules.
Issue: OENO Macrowine 2023
1. Université Bordeaux, Bordeaux INP, INRAE, OENO, UMR 1366, ISVV, 33140 Villenave d’Ornon, France
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ripeness, grape, extractability, wine, stability