Wine without added SO₂: Oxygen impact and color evolution during red wine aging

SO₂ play a major role in wine stability and evolution during its aging and storage. Winemaking without SO₂ is a big challenge for the winemakers since the lack of SO₂ affects directly the wine chemical evolution such as the aromas compounds as well as the phenolic compounds. During the red wine aging, phenolic compounds such as anthocyanin, responsible of the red wine colour, and tannins, responsible of the mouthfeel organoleptic properties of wine, evolved quickly from the winemaking process to aging ^[1]. A lot of new interaction and molecules occurred lead by oxygen^[2] thus the lack of SO₂ will induce wine properties changes. Nowadays, the phenolic composition of the wine without added SO₂ have not been clearly reported. The aims of this study is to characterise the impact of oxygen on the phenolic composition of the wine without added SO₂ during ageing. A comparison between wines with and without SO₂ have been performed. For the experiment, an identical wine without added SO₂ during the vinification step have been divided in different steel tank and an increase amount of oxygen have been introduce. Oxygen consumption have been followed and after complete consumption of oxygen, wine samples have been collected for chemical and sensory analyses, and the same amount of oxygen have been introduce again. Different phenolic analysis have been performed. Anthocyanin’s evolution have been followed from the monomeric anthocyanin to the polymerized pigments. Condensed tannins evolution have also be carry out as well as the crown procyanidins. A correlation between the oxygen amount and anthocyanin’s evolution have been determined as well as the tannin’s evolution.

References:

1. Drinkine J. et al. (2007) Ethylidene-bridged flavan-3-ols in red wine and correlation with wine age. Journal of Agricultural and Food Chemistry, 55: 6292–6299, https://doi.org/10.1021/jf070038w
2. Zeng L. et al. (2016) Structures of polymeric pigments in red wine and their derived quantification markers revealed by high-resolution quadrupole time-of-flight mass spectrometry: Identification of polymeric pigments and their quantification markers. Rapid Communications in Mass Spectrometry, 30: 81–88, https://doi.org/10.1002/rcm.7416