Abstract
Changes in phenolic compounds, chromatic characteristics, acetaldehyde, and protein-reactive tannins associated with oxidative aging were studied in Sangiovese wines with varied tannin T/anthocyanin A ratios. For this purpose, three Sangiovese vineyards located in Tuscany were considered in the 2016 vintage. To obtain wines with different T/A ratios, two red wines were produced from each vinification batch: a free run juice with a lower T/A ratio and a marc pressed wine with a higher T/A ratio. An overall of six wines with T/A ratios ranging between 5 and 23 were produced. An oxidation treatment (four saturation cycles) was applied to each wine. Average and initial oxygen consumption rates (OCR) were positively correlated to VRF/mA (vanilline reactive flavans/monomeric anthocyanins) and T/A ratios while OCRs were negatively related to the wine content in monomeric and total anthocyanins. The higher the A content was, the greater the loss of total and free anthocyanins. A significant lower production of polymeric pigments was detected in all pressed wines with respect to the correspondant free run one. A gradual decrease of tannin reactivity toward saliva proteins after the application of oxygen saturation cycles was detected. The results obtained in this experiment indicate that VRF/mA and T/A ratios are among the fundamental parameters to evaluate before choosing the antioxidant protection to be used and the right oxidation level to apply for a longer shelf-life of red wine.
Highlights
During red wine aging the exposure to low amounts of oxygen, as occurs during oak-barrel aging and/or micro-oxygenation, can produce several improvements
The accumulated oxygen consumption was plotted vs. time, and the initial and average oxygen consumption rate of that wine for saturations 2–4 was determined as previously reported by Ferreira et al (2015)
Initial and average consumption rates are instead negatively related to the wine content in monomeric and total anthocyanins; for all these analytes the negative correlation is stronger with average oxygen consumption rates (OCR) (Table 2)
Summary
During red wine aging the exposure to low amounts of oxygen, as occurs during oak-barrel aging and/or micro-oxygenation, can produce several improvements Among those most studied are: the increase of pigment stability (Atanasova et al, 2002; Cano-López et al, 2008), the decrease of astringency, and bitterness due to reactions of sensory active tannins (Cejudo-Bastante et al, 2011a; Gambuti et al, 2012), and the decrease of vegetative and reduction aroma (Cejudo-Bastante et al, 2011b; Gambuti et al, 2017). Today finding simple useful models able to predict how the wine is going to respond to oxygen exposure is one of the most challenging goals These models and knowledge of the wine’s key compounds affecting wine evolution in contact with oxygen are fundamental for a proper management of wine aging in both the winery and on the market.
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