RED WINE FROM BRS VIOLETA WITH MALOLACTIC FERMENTATION: BEHAVIOR OF THE PHENOLIC COMPOUNDS AFTER TREATMENT WITH GRANULATED FRENCH OAK DURING STORAGE AT DIFFERENT TEMPERATURES

Unlike traditional wine producing countries, the basis of wine production in Brazil is from cultivars of american origin (Vitis labrusca e Vitis bourquina) and interspecific hybrids (crossing of varieties viniferas and americans). The hybrid grape BRS Violeta (BRS Rúbea x IAC 1398-21), specially, has been highlighted because of the high content of phenolic compounds (CPC) and potential for the elaboration of young and aged wines. The evolution of phenolic compounds of wine of the BRS Violeta, produced with malolactic fermentation, after the treatment with unroasted granulated oak French (F) origin (Quercus petraea) and storage at three temperatures for 60 days was evaluated. Samples of young red wines, without oak treatment, were used as controls (C), and subjected to the same storage conditions. Therefore, the newly elaborated wines were treated with oak (Exclusivas Arraez Bravo, Cuidad Real, Spain) in the dosage of 3 g/L at 15 °C for 30 days (free of oxygen and light). Subsequently, all wines were transferred to amber glass bottles (80 mL) and stored in greenhouses, type B.O.D., at 16 °C, 25 °C e 50 °C. Periodic analysis (0, 5, 15, 30 and 60 days) of CPC were performed, according to the spectrophotometric method of Folin-Ciocalteu, with the results expressed in mg equivalent to gallic acid per liter of wine. All experiments were performed in duplicate. After the evaluation of the phenolic compounds evolution in wines with and without treatment with oak, it was verified that at the first 5 days of storage at 16 °C there were further increases next to 20% in the total contents while at 25 °C and 50 °C there were further increases next to 10% and 15% in relation to control wines and the ones treated with oak, in that order. Between the 15 and the 60 days, all the wines submitted to 16 °C and 25 °C showed a stabilization behavior in the phenolic compounds, while at the temperature of 50 °C, after 15 days, all the wines showed a decrease in phenolic compounds. The wine treated with oak, however, showed a numerically lower reduction. This better stability of phenolic compounds in treated wines can be the result of a transfer of ellagitannins with antioxidant activity present in the French oak composition, improving its protection against oxidation.