Utilização de fibras de celulose e tanino gálico na elaboração de vinho branco proveniente de uvas com Botrytis cinerea

Abstract

Serra Gaúcha has an excellent oenological capacity to produce quality still white wines. However, due to the occurrence of natural phenomena in Rio Grande do Sul, excess precipitation and humidity favors the emergence of diseases directly in the bunches, resulting in a drop in production, poor health in the grapes and loss of quality of the grapes and wine. . Botrytis cinerea is a fungus that causes gray rot in grapes and is present in all vineyards around the world. This study aimed to evaluate the use of cellulose fibers to reduce the negative effects caused by Botrytis cinerea in musts and wines from Chardonnay grapes (Vitis vinifera L.) and contribute to the development of a new technology to improve the quality of wines. whites. The effects of cellulose fibers were compared with a commercial gallic tannin recommended for the same purpose. This commercial gallic tannin has a considerably higher purchase price than cellulose, around 65% more expensive. The experiment consisted of eight treatments and three replications with different doses of each product. The musts and wines obtained were analyzed for basic composition, volatile compounds, color index and phenolic compounds, according to the official Brazilian methodology, and the resulting wines were sensorially evaluated by a team of twelve qualified tasters. The presence of rot caused by Botrytis cinerea altered the composition of the musts and the quality of the wines obtained. The musts obtained from rotten grapes (T2) showed the highest levels of volatile acidity and gluconic acid due to the action of oxidative enzymes present in the fungus. Both the use of gallic tannin and cellulose fiber were efficient in reducing the volatile acidity levels of the must, presenting lower values than the must with untreated rot (T2). The addition of 1.5 g.Kg-1 of cellulose fibers (T8) resulted in the lowest concentrations of acids coumaric and epicatechin in wines. Few variations were found between the wines obtained in terms of fatty acid analysis. However, regarding sensory characteristics, wines obtained from healthy untreated grapes (T1) exhibited a general trend of greater positive intensity, clarity and quality, a fact that is justified by the quality of the grape being linked to better acceptance of the final product. However, the use of cellulose fibers (T6, T7 and T8) favored the results of the vinification of white Chardonnay grapes with Botrytis cinerea, mitigating its negative effects, and proved to be more effective than the use of commercial gallic tannin, approaching the values obtained from healthy grapes in the global assessment of sensory analysis. [resumo fornecido pelo autor]