How closure oxygen permeability impacts tannin evolution in long-term aged red wines: breaking analytical barriers using UHPLC–UHRMS metabolomics and MS/MS-based molecular networking

Abstract

The significant role played by condensed tannins (CTs) in oenology has encouraged extensive research on these compounds. Indeed, this class of polyphenolic compounds, composed of flavan-3-ol polymers, contributes to the modulation of colour, astringency and bitterness perception of red wine, key sensory attributes that shape wine quality and consumer acceptance. CTs are highly reactive compounds, and during bottle aging, oxygen is a key factor governing their molecular reactivity. In this closed system, oxygen transfer mainly occurs through the closure, and promotes molecular reactions, including oxidation, driving CT structural rearrangement that ultimately affects wine quality. However, despite their importance, understanding the structural evolution of CTs during bottle aging remains a significant analytical challenge, and the impact of closure oxygen permeability on CT structural evolution has yet to be explored. This study explores how closure oxygen permeability influences CT structural evolution over 17 years of bottle aging and which molecular markers define and differentiate these changes according to closure type. For the first time, thioglycolysis1 of isolated tannins from wines was combined with powerful analytical approaches including untargeted UHPLC–UHRMS Orbitrap metabolomics, which compares CT evolution profiles, and MS/MS-based molecular networking2 (MN) to characterize discriminant markers. Wines (70% Cabernet Sauvignon, 30% Merlot) were produced under identical winemaking conditions, aged in oak barrels, and stored under the same conditions, differing only in closures type, which varied in oxygen permeability. Statistical analyses revealed a clear separation of tannin profiles according to closure type (45.5% of the variance), highlighting groups of discriminant variables significantly related to closure permeability. Molecular networks identified 136 oxidative and non-oxidative markers, including 69 previously unreported. MS/MS analyses revealed dimers and trimers, indicating linkage between tannins and other compounds, including anthocyanins and pyranoanthocyanins. Furthermore, MN revealed closure-dependent quantitative differences in marker distributions. Overall, this work improves characterization of CT evolution in complex wines, provides scientific validation of the importance of closure choice, and supports high-throughput tools for understanding complex enological processes.

References

1. Mouls, L. and Fulcrand, H. (2015). Identification of new oxidation markers of grape-condensed tannins by UPLC–MS analysis after chemical depolymerization. Tetrahedron, 71(20), 3012–3019.

2. Razafindrabenja, L. E.; Suc, L.; Véran, F.; Verbaere, A.; de Sousa Dias, A. L.; Meudec, E.; Galy, N.; Tixador, D.; Loisel, C.; Mouls, L. and Sommerer, N. (2025). Combining AcquireX™ data acquisition and Feature-Based Molecular Networking approach to deeply explore oxidation markers of condensed tannins after depolymerization. Food Chemistry, 483, 144207.