Abstract
The evolution of polyphenols in Syrah red wines during bottle ageing involves numerous oxidative and non-oxidative reactions. It can be modulated by the choice of oxygen permeability of the cork closure used. Predicting, characterizing, and controlling this evolution through this avenue is a significant challenge for the winemaking industry, particularly for adapting closures based on the wine ageing potential. During this thesis, two types of analytical approaches for monitoring the chemical transformations in the evolution of Syrah red wines were used: a non-targeted approach and atargeted approach.In the non-targeted approach, predictive models for three accelerated aging tests of red wines (chemical, enzymatic, and thermal) were established. They proved to be accurate and powerful (R² > 0.89 for all models). These models highlighted the importance of polyphenols in the wines' ability to resist oxidation during aging. Non-targeted metabolomic studies of Syrah red wines during aging were able to identify molecular markers of aging and cork permeability. Thus, we demonstrated the significance of CHO-type molecules (polyphenols) and CHON-type molecules (peptides) in young wines and an increase in CHO compounds (pyranoanthocyanins), CHNOS, and CHOS compounds (sulfonation reactions) during aging.As for the targeted approach, the study of the impact of acetaldehyde and phenolic composition on the sensory perception of Syrah red wines was initially examined. The polyphenol concentration will affect the combination of acetaldehyde. Furthermore, depending on the acetaldehyde concentration, descriptors such as "vegetal," "red berries," or "pastries" were overexpressed. These observations suggest that acetaldehyde can interact with volatile or non-volatile compounds, creating antagonistic or synergistic effects. In a second step, the synthesis of three aging markers (vitisin B, malvidin-ethyl-catechin, epicatechin sulfonate), followed by the development of a quantification method using UHPLC-QqQ-MS, was carried out. The kinetics of evolution showed a decrease in native polyphenols and an increase in targeted markers during aging. Additionally, an effect of cork permeability on these compounds (native polyphenols or markers) was demonstrated, except for the formation of flavanol sulfonates.