Emprego de manoproteína na maturação de vinho tinto 'merlot' da serra gaúcha

Abstract

Serra Gaucha, in Brazil, is a region charaterized by it’s humid climate and excess of rainfalls during grape ripening, which makes producers, to adopt a preventive method agains diseases, harvest fruits before their complete maturation. One must pay attention to grape complete maturation, not only because of sugar contents but also because of fenolic maturation, which play important role on wine quality, mainly anthocianins and tanins. Tanins are responsible for mouth tactile sensations as astringency, a characteristic of wines produced in Serra Gaucha and regions with similar climate conditions. Enologic ingredient companies put in the market many options of product which help vinification reducing problems related to weather/production problems which can’t be controlled in the vineyard. Aiming to evaluate the interactions between mannoproteins and tannins, influencing their complexation, were tested different doses of mannoproteins on red wine obtained from cv. Merlot from Serra Gaucha. The mannoprotein used in this experiment is called Mano Pro 21%®, and it’s minimum and maximum doses recommended by the manufacturer are 1,5 – 3,0 g.L-1, respectively. Classical vinification method was adopted, with six days of maceration during alcoholic fermentation and malolatic fermentation. Before maturation started, at wine bottles they were trafficked 4,5L and received their treatments, which are: T1, with no addition of mannoproteins; T2 received the minimum dosage (1,5g.l-1); T3 received 2,75g.L-1 and T4 received the maximum dosage (3g.L-1). All treatments were triplicated, which means there were 54L of wine. After six months of maturation, the wines were bottled in bottles of 750 ml and 20 days later were subjected to physical and chemical analysis by infrared spectroscopy by Fourier transform (FTIR) and Gelatin Index and then statistical analysis was performed, were subjected to analysis of variance and the results were compared by the Tukay 5% test with ASSISTAT® program. The results of both the basic physical and chemical analysis as the specific phenolic compounds showed no statistical difference, but interesting distinct values, mainly showed that there is influence the determination of manoproteína maturation of wines. In treatments T3 and T4, which received higher doses of mannoproteins and feature values higher gelatin content near to 90%, showing that despite the classical vinification wine has a good phenolic structure. In T2, it is clear that the value of 77% of reactive tannins, shows the action of the employee product, even at the lowest dose of the product, indicating a softening of astringency which was the goal of the experiment. These results show the effectiveness of mannoproteins. Based on the results, one can conclude that the use of Mano Pro 21% employed in red wine maturation is efficient even in minimum dosage, cause even this treatment showed satisfatory results related to the softening of astrigency of final wine.