Polyphenolic and aroma profile of Vranec wines fermented with isolated yeasts from Tikveš wine area

Wine contains a number of polyphenolic constituents classified as flavonoids and non-flavonoids that play a major role in enology. They contribute to wine sensory characteristics, especially colour, flavor and astringency and therefore, to the differences between red and white wines. On the other hand, wine aroma is a one of its most important characteristics produced by a complex balance of different groups of volatile compounds, belonging to alcohols, esters, aldehydes, lactones, terpenes, norisoprenoids and phenols. In this study, Vranec wines, the most important red variety in Republic of Macedonia, will be subject of investigation. Fermentation yeasts will be, for the first time, isolated from local grapes and identified, followed by application to the grape mush for fermentation. This project will be focused on determination of the effects of isolated yeast strains on the content of total phenolics, anthocyanins, colour, volatile compounds and antioxidant activity. For this purpose three different techniques will be applied: spectrophotometry, GC-QQQ-MS and electrochemical voltammetric methods. Spectrophotometry will be used for analysis of total phenolics, anthocyanins and colour The aroma composition of the wines will be characterized by means of gas chromatography-triple quadrupole mass spectrometer (GC-QQQ MS). Liquid-liquid extraction with dichlorometane will be used for extraction and concentration of volatile compounds from the wine. Higher alcohols, esters, and fatty acids are expected to be identified and quantified. In addition, electrochemical methods will be applied to characterize the polyphenols in wine using square-wave and cyclic voltammetry and to determine the antioxidant activity. Statistical treatments, including means, standard deviations, one-way ANOVA, Student–Newman Keuls test, Factor Analysis and Cluster Analysis will be performed in order to ascertain possible significant differences between the studied wines