Impact of conditioning treatments on quality characteristics of Viorica Wines

Abstract

The quality of a wine is directly related to the chemical composition of the grapes, but also to the applied winemaking techniques. In Republic of Moldova are cultivated mainly European grape varieties, but lately local varieties are becoming more popular and demanded by consumers. One of the most famous local selection grape variety is Viorica – an interspecific hybrid which has a comprehensive resistance to biotic and abiotic environmental factors with great technological potential for quality wines production. In order to carry out this study, the grapes of local selection grape variety Viorica were manually harvested from the Milestii Mici village, PGI Codru and processed under micro-winery conditions at the of the Technical University of Moldova. The studied wines were produced with and without addition of ß-glucosidase and pectinase enzymes for revealing terpenic varietal aromas from their precursors and to facilitate the clarification process. After 3 months, the wines were submitted to conditioning treatment with bentonite and pea protein preparations. The quality characteristics (alcohol content, total and volatile acidity, color intensity and hue, oxidation test) of the studied wines were established by methods recommended in the national and international standards. The sensory evaluation was conducted by a panel of experts using a 100-point system. In this study, the enzyme addition did not have a significant effect on the main physical-chemical parameters, except that the fermentation proceeded faster due to the enzymes. Subsequent the spectrophotometric analysis of wines, the chromatographic parameters were calculated: the total polyphenol index, the color intensity and hue, and also the oxidation behavior. The sensorial evaluation of studied wines highlighted the typicality of Viorica variety: acacia, linden flowers, citrus fruits and a bright flavor of basil. Overall, the wine produced with enzyme addition had by near 20 % higher results, especially regarding aroma evaluation. Following the carried study, it can be mentioned that the addition of enzymes affected the color intensity and hue of the wine: in the sample with enzymes, the indicators were higher with 10 %, which can be explained by the increased extraction of phenolic compounds besides the terpenic ones. According to the data obtained as a result of polyphenols oxidative medium test, the wine obtained with addition of enzymes has a lower risk of oxidation by more than 5 times, which confirms the theory that enzymes reduce the risk of oxidation of white wines. The conditioning treatments decreased by 32 – 40 % the total polyphenol index and by 34 % the oxidation risk, therefore conditioning treatments can effectively reduce the content of oxidized polyphenols. It can be resumed that the choice of winemaking techniques has a very important role for the overall and sensorial quality of the wine obtained from local selection grape variety Viorica.