Cork impact on red wine aging monitoring through ¹H NMR metabolomics: A comprehensive approach

Cork stoppers have a significant impact on aging as a place of gas exchange. This study investigates the effects of different cork closures on red wines using ¹H NMR metabolomics approach. The objective is to understand how different cork stoppers affect the chemical evolution of wine during aging. Six Syrah wines from the Côtes du Rhône and Languedoc-Roussillon regions, matured in either steel tanks or oak barrels, were bottled with four micro-agglomerated cork stoppers. Over 24 months, wines were analyzed using ¹H NMR spectroscopy. Data were processed using multivariate analyses: principal component analysis (PCA), hierarchical cluster analysis (HCA), and orthogonal projections to latent structures discriminant analysis (OPLS-DA). The analyses revealed significant changes along the wine aging process. Distinct chemical signatures were identified for wines at the initial and 24-month stages. At the initial stage, wine maturation conditions, stainless steel tank or oak barrel, seem to impact wine constituents, including methanol, ethyl lactate, acetic acid, myo-inositol, and isobutanol. Finally, corks with higher oxygen transfer rate (OTR) showed higher content in acetoin, suggesting its application as an oxygenation marker of wines. The findings highlight the complex role of cork permeability in red wine aging, suggesting that the choice of cork can be strategically used to steer the aging process and enhance wine quality.