Wine aging : a bottleneck Story ?

Abstract

The sporadic oxidation of white wines remains an open question, making wine shelf life a subjective debate. Through a multidisciplinary synoptic approach performed as a remarkable case study on aged bottles of white wine, this work unraveled a yet unexplored route for uncontrolled oxidation.

The objective was to characterize the contribution of stoppers on bottle aging of white wines in real condition, with particular emphasis on the bottleneck/stopper interface. Oxidation was observed in a few bottles of white wine coming from the same vintage and production lot, i.e., visual examination showed obvious color evolution. To investigate this phenomenon, a multidisciplinary approach was designed combining sensory evaluation, targeted and non-targeted chemical analyses, and physical investigation with both the wine and the system composed of the stopper and the bottleneck.

First, both the sensory evaluation and the chemical analyses of classical enological parameters unambiguously revealed the different oxidative states of the four bottles, with, for each vintage, one bottle being oxidized compared to the other. Further, a metabolomics analysis was performed by FT-ICR-MS. A total of 532 masses were significantly more intense in Ox or NoOx wines, of which 175 m/z values were distinct for Ox wines and 357m/z values for NoOx wines. Lastly, the oxygen transfer rate was first determined through the whole system composed of the glass bottleneck containing the cork stopper, then on the cork stopper alone with the interface glued (after uncorking). The diffusion coefficient of oxygen through the cork stopper alone was similar for all stoppers. However, the transfer of oxygen through the cork/glass bottleneck system was higher than through the cork alone, and much higher for bottles containing the Ox wines. It shows unambiguously that the transfer of oxygen at the interface between the cork stopper and the glass bottleneck must be considered a potentially significant contributor to oxidation state during the bottle aging, leading to a notable modification of a wine’s chemical signature.