Influência climatológica na 'cabernet sauvignon' de Dom Pedrito, RS, safra 2016

Abstract

The Campanha Gaúcha region is the second producer of fine wines in Brazil, mainly red wines. In this scope is 'Cabernet Sauvignon', a variety of French origin, being the most cultivated in Brazil in the list of Vitis vinifera grapes, having a great commercial appeal, being used for the elaboration of young and guardian wine. In order to produce a quality wine, it is necessary to understand what factors affect the process, from the field to the bottle. Adequate phenolic maturation results in a polyphenolic filler suitable for vinification of red grapes. Factors such as total acidity, pH, color, total polyphenols are preponderant for the production of quality wines. In this context the 'Cabernet Sauvignon' of the Campanha Gaúcha region has presented high levels of potassium present in must and wine, which determines wines of low acidity and high pH values, this affecting several qualitative factors of the wine. In addition to biological factors, management, vines, are directly influenced by climatic issues such as temperature, radiation, thermal amplitude, precipitation. This study was carried out to evaluate how climatic conditions influence the dynamics of potassium uptake, phenolic maturation, and qualitative parameters of wine color, pH, total acidity, total polyphenols, anthocyanins and tannins. The Cabernet Sauvignon grapes used for the study were from a commercial vineyard, from the 2016 crop, located in the Dom Pedrito region, RS, where potassium and phenolic maturation were evaluated in the field, with weekly berries collected during the maturation period of the variety, with subsequent evaluation of the must. Qualitative parameters of anthocyanins, total polyphenols, tannins, color in the absorbances 420, 520, 620, pH and total acidity were evaluated in the finished final wine. All the data collected in must and wine were statically analyzed with meteorological variables of minimum and maximum air temperatures, thermal amplitude, incident radiation and precipitation, in order to evaluate the climatic influences in the parameters collected. It was observed that the potassium is a great influence of the total acidity and pH in the berry, where the main effect occurs during the elaboration of the wine with the precipitation of the potassium bitartrate, altering the pH and total acidity magnitudes. Potassium uptake was influenced by climatic parameters that modify photosynthetic kinetics by increasing the amount of potassium absorbed. Likewise, potassium, pH and total acidity influenced the phenolic maturation of the variety. The elaborated wine presented physico-chemical requirements not very suitable for a wine of quality, mainly as regards the magnitude of the pH. Likewise, color, anthocyanins, tannins, total polyphenols were out of adequate ranges. The total acidity in addition to being outside of an adequate range was influenced during the elaboration process, which demands more in-depth studies as a way of understanding its expression in wine. Tannins were shown to be closely linked with total acidity, with pH, color at 420 and 620 influenced by precipitation and fluctuations in thermal amplitude and radiation. Ideal levels of anthocyanins are directly linked to the thermal amplitude.