Experience of Cold Maceration on ‘Touriga Nacional’ Wine Varieties in the Campanha Gaúcha Region, Brazil

Aims: The objective of this work was to evaluate the use of cold pre-fermentative maceration in wines elaborated with the Touriga Nacional cultivar in the region of Campanha Gaúcha. 60 kg of grapes of the Touriga Nacional cultivar, with 19° Brix, were obtained from the municipality of Bagé -Rio Grande do Sul, Brazil.

Study Design: The microvinification was divided into two treatments, with the first treatment (T1) corresponding to traditional maceration carried out for 8 days at temperatures of 22°C, and the second treatment (T2) corresponded to the cold pre-fermentative maceration performed for three days, with temperatures of 5 to 8°C. Each treatment was replicated three times contented 4.6 liters of wine, finally.

Place and Duration of Study: The experiment was carried out at the experimental winery and the physicochemical analyses were carried out at the TPOAV laboratory of the Federal University of Pampa (UNIPAMPA), Dom Pedrito campus, during the cycle 2016/2017.

Methodology: The first treatment (T1) corresponds to traditional maceration, where the maceration occurred along with the alcoholic fermentation, in which the skins remained in contact with the wine for eight days under a temperature of 22°C. The second treatment (T2) corresponds to the cold pre-fermentative maceration, where the must remain in a cold room (5 to 8°C) for three days, and afterward, the alcoholic fermentation was carried out in the presence of the grape skin for eight days, at the same temperature as the previous treatment. The variables analyzed were pH, total acidity (meq.L-1), volatile acidity (gL-1), alcoholic content (% v/v), reducing sugars (gL-1), gluconic acid (gL-1), phenolic compounds, color indices (420, 520 and 620 nm), color intensity (420 + 520 + 620 nm), and color tone (420/520 nm). The total polyphenols index (TPI), ethanol index (%), HCL index (%), total anthocyanins (mg.L-1), total tannins (gL-1) and gelatine index (%) were also analyzed. The wine sensory analysis was performed immediately after bottling.

Results: The alcoholic content of wines corresponding to the traditional maceration (T1) was higher than that observed in wines submitted to cold pre-fermentative maceration (T2). In relation to pH, T2 obtained a lower value than T1, conferring a more acidic character to the wine. The color tone of T1 was higher than T2. There was no significant difference in the other indices analyzed.

Conclusion: The cold pre-fermentative maceration in Touriga Nacional wines seems to give positive results, even if the statistical analysis evidenced significant results only for the wine sensory global pleasantness. The results indicate that other techniques should be evaluated to increase the extraction of the phenolic compounds. Further studies on the Touriga Nacional cultivar and the vinific.