Exploring the impact of different closures on tannin evolutions by combining metabolomic approach and feature-based molecular networking

Abstract

Condensed tannins (CTs), polymers of flavan-3-ols, are a class of polyphenolic compounds that play a significant role in the organoleptic qualities of red wines, particularly influencing color, astringency and bitterness. These properties are highly dependent on size and structure of these compounds. Moreover, from grape harvest to wine consumption, exposure to oxygen induces diverse molecular reactions such as oxidation, increasing molecular diversity and complexity of wine composition, ultimately affecting wine quality. Particularly during aging process, wine undergoes many compositional changes, making its evolution in the bottle a subject of great interest to ensure consistent quality over time. While wine closures are known to regulate oxygen levels¹, the impact of their oxygen permeability on the structural evolution of CTs during bottle aging has yet to be explored.

In this work, a comprehensive analysis of the profile of red wines over 15 years was conducted. The aim was to study the impact of closure type on the evolution of tannin structures and to identify oxidation markers associated with wine aging. Wines were produced under same winemaking conditions but sealed with closures characterized by different oxygen permeability (screw cap, synthetic, traditional and agglomerated corks). To conduct this study, due to the difficulty in precisely characterizing tannins, biological triplicates of wine samples were first fractionated² to isolate tannins from the matrix. Chemical depolymerization of tannin fractions was then performed using a thioglycolysis reaction³. From these depolymerized tannin fractions, two combined analytical approaches has been developed. The first approach involved untargeted UHPLC-Q-Orbitrap metabolomics analysis, which compared the wine profiles to discover specific discriminating markers linked to closure permeability. The second approach employed targeted method, using an intelligent MS/MS data acquisition with AcquireX™ Deep Scan workflow, followed by Feature-Based Molecular Networking⁴.

The obtained results showed that closure oxygen permeability has a significant influence on the evolution of tannin structures during bottle aging, indicating that the selection of wine closures should be considered in preserving wine profile over time. Several aging-related oxidation markers were identified, including several that were previously unreported. Furthermore, this study showcased the strong potential of advanced analytical tools in characterizing complex metabolites and open new perspectives for research into wine quality.

References

[1] Ugliano, M. (2013). Oxygen contribution to wine aroma evolution during bottle aging. J. Agric. Food Chem. 61, 6125–6136.

[2] Deshaies, S., Garcia, F., Suc, L., Saucier, C., and Mouls, L. (2022). Study of the oxidative evolution of tannins during Syrah red wines ageing by tandem mass spectrometry. Food Chemistry 385, 132538.

[3] Mouls, L., and Fulcrand, H. (2012). UPLC‐ESI‐MS study of the oxidation markers released from tannin depolymerization: toward a better characterization of the tannin evolution over food and beverage processing. J. Mass. Spectrom. 47, 1450–1457.

[4] Zhang, M., Otsuki, K., and Li, W. (2023). Molecular networking as a natural products discovery strategy. Acta Materia Medica 2, 126–141.