EFFECT OF MICRO-OXYGENATION IN COLOR OF WINES MADE WITH TOASTED VINE-SHOOTS

Abstract

The use of toasted vine-shoots (SEGs) as an enological tool is a new practice that seeks to improve wines, differentiating them and encouraging sustainable wine production. The micro-oxygenation (MOX) technique is normally combined with alternative oak products with the aim to simulate the oxygen transmission rate that takes place during the traditional barrel aging. Such new use for SEGs implies a reduction in color due to the absorption by the wood of the responsible compounds, therefore, given the known effect that MOX has shown to have on the modification of wine color, its use together with the SEGs could result in an interesting implementation with the aim to obtain final wines with more stable color over time.

To achieve this, Tempranillo wines were in contact with their own SEGs and with those from Cabernet Sauvignon variety in two different doses (D1 and D2). SEGs were added at the end of malolactic fermentation and two fixed doses of micro-oxygenation (low, LMOX; and high, HMOX) were considered during the entire period of SEGs contact. At the end of the SEGs-MOX treatments, wines were bottled and stored at temperature and humidity-controlled conditions for 6 months. Wines were characterized in terms of visible spectra, CIELab and individual anthocyanin compounds (HPLC-DAD) to study the color evolution at bottling time and after 3 and 6 months in the bottle.

The results showed that at the end of the treatments, wines micro-oxygenated with the lower dosage (L-MOX) received 6.24 ± 0.87 mg/L per month while those from higher dosage (H-MOX) received 11.91 ± 0.71 mg/L per month. The spectral information showed that in general there was a decrease in the color of SEGs-MOX wines with respect to the control, being more pronounced at bottle time. This reduction was greater when the higher SEGs dose were used, but MOX doses considered did not seem to have a differentiating effect. Specific, only in wines with Cabernet Sauvignon SEGs and D1 the H-MOX produced less color loss; however, for Tempranillo SEGs, the highest dose (D2) combined with L-MOX showed the least color reduction. This reduction in color was observed during the bottle time, being less pronounced after 6 months. The greatest reductions were observed for the red tones (A520) and to a lesser extent for the blue ones (A620). The anthocyanin pormenorized analysis revealed the same behavior, being malvi-din-3-O-glucoside the one that presented the greatest decrease. These first results could indicate that MOX would have to establish it based on SEGs variety and dosage.