Avaliação de parâmetros enológicos, sensoriais e biológicos em vinhos espumantes : efeito de agentes moduladores /

Abstract

The evaluation of enological, sensorial and biological parameters in sparkling wines (SW) Charmat (brut and demi-sec) and Champenoise (brut) was performed in experimental and industrial samples, provided by seven wineries, located in Bento Gonçalves and Garibaldi, Rio Grande do Sul. The main objectives were: a) Determine the beverage standards to the SW; b) quantify the ascorbic acid levels in SW; c) study the SW phenolic profile by spectrophotometry UV an high performance liquid chromatography (HPLC); d) evaluate the SW antioxidant capacity by in vitro and in vivo tests; e) verify the presence of -glucosidase activity in SW; f) perform the sensorial analysis of the SW with the participation of an experts group by the rules of OIV (International Organization of Vine and Wine); and g) compare the data between the three blocks analyzed. The results obtained were: a) the beverage standards were in accordance with the legal limits; b) the ascorbic acid levels were influenced mainly by the grape used on the base wine production, and a second moment, by the yeast metabolism during the fermentations and sur lie; c) for the classes of phenolic compounds (total polyphenols, total flavonoids, total hidroxycinnamates and oligomeric procyanidins) we observed that the reactions of hydrolysis and/or polymerizations (linked with the base wine constitution) were influenced by the sur lie; SW showed important amounts of gallic, caffeic and ferulic, (+)-catechin, (-) epicatechin, transresveratrol, trans-piceid and tyrosol; d) all the samples of SW analyzed shown important antioxidant activity, both in vitro (DPPH•, SOD-like and CAT-like tests) as in vivo (Saccharomyces cerevisiae assay); e) was verified the presence of -glucosidase activity in SW and its action was constant during the sur lie studied; f) Brazilians SW presented a great sensorial quality, at the same level of the French and Italian ones; furthermore, the perlage can act positively on the antioxidant activity (CAT-like); and g) we find correlations between the phenolic profile and mineral composition of the SW (Charmat and Champenoise, Brut and Demi-sec) with the antioxidant capacity of them. In synthesis, the results conclude that: 1) the production of SW with highest antioxidant capacity through specific enological techniques is possible; 2) is the sur lie (ageing on lees) and not the elaboration method (Charmat or Champenoise) that determines the changes in the biological activity, mainly due to a greater influence on the compounds related with the antioxidant activity observed in SW; and 3) the sugar concentration can change the antioxidant capacity, increasing or decreasing it, is related with the - glucosidase activity in SW (this stayed unchanged during the sur lie, therefore, is related with the others biochemical reactions of the process). This work contributed to the understanding of the differences between the SW production methods, showing that both have the same qualitative potential aspects when compares the industrial, commercial, or scientific points of view.