The importance of post-bottling oxygen to wine aroma development has been demonstrated. However, from a practical point of view, the degrees of oxygen exposures needed to induce significant aroma modification remain to be established. In addition, certain styles of wine are more responsive to oxygen than others, possibly reflecting the key role of specific aroma compounds with lower/higher oxygen sensitivity in their sensory profile. In this study, 36 wines from different grape varieties were submitted to sensory descriptive analyses.  The wines were in an age bracket of 9-19 months (whites), 5-11 months (ros�), 12-48 months (reds). Each wine had received at least two different oxygen exposure levels by means of different closures, with some wines tasted at different time points. In total, 96 wines were tasted. When considering only the contribution of closure-derived oxygen, significant differences in fruity attributes where observes when wines were exposed to levels oxygen between approx 1-3 mg O2 (white wines), 0.4-1.6 mg O2 (ros�), and 2-5.5 mg O2 (reds). On the contrary, complex aroma descriptors such as mineral and empyreumatic show rather narrow range of variability (approx 1-1.5 mg O2 in whites and 2-3.5 mg O2 in reds), indicating that expression of these attributes requires precise oxygen exposure levels. Oxygen levels inducing differences in reduction were strongly wine-dependent.Analyses conducted on selected wines indicated that esters, largely associated with wine fruity aromas were not affected by oxygen. Conversely, the fruit-enhancer damascenone increased with higher oxygen exposure, while fruity thiols such as 3SH decreased. A number of compounds potentially linked to the empyreumatic attribute varied with oxygen exposure, including benzyl mercaptan, acetyl pyrazine, and 2-methyl-3-(methyldithio)-furane. H2S and methyl mercaptan were mostly implicated with reduction attribute, and they might negatively affect expression of fruity attributes.

Critical oxygen levels affecting wine aroma: Relevant sensory attributes, related aroma compounds, and possible mechanisms

248th National Meeting (2014)

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