## 3 Results and Discussion
### Quantification of Phenolic Compounds in Must and Wine
If the amounts of sulfonated dimers, trimers and larger oligomers are also greater than the native proanthocyanidims, such a large fraction of modified condensed tannin affects wine taste and astringency. These results are in agreement with the structure explained by [PERSON] et al. [28], where sodium epicatechin-(4\(\upbeta\))-sulfonate formed in a reaction of condensed tannin with bisulfite at pH 5.5 and 100 \({}^{\circ}\)C. Also, [PERSON] et al. [32] demonstrated that epicatechin-(4\(\upbeta\))-sulfonate and procyanidin B2-4\(\upbeta\)-sulfonate were generated in a reaction of apple tannins with bisulfite in a model wine. Phenolic acids are responsible for taste aspects such as wine bitterness and astringency [30]. The must analyzed in this study contained the highest amount of phenolic acids (75.0 mg/L), and their concentration decreased along the wine-making process. Statistical differences (\(p<0.05\)) were regarding the temperature factor. A higher fermentation temperature (20 \({}^{\circ}\)C) allowed for retaining more phenolic acids than at 12 \({}^{\circ}\)C in both fresh and matured wine. The average content of phenolic acids in the wine after fermentation was 36.8 and 12.8 mg/L at 20 and 12 \({}^{\circ}\)C, respectively. In the variants of wine fermented at 20 \({}^{\circ}\)C, the content of phenolic acids decreased significantly after maturation, while it remained at a similar level in the wine fermented at a lower temperature. Yeast strain had no effect on the content of phenolic acids in the wine after fermentation, but significant changes were detected following maturation (\(p<0.05\)). Phenolic acid content was the lowest in the matured wine produced by spontaneous fermentation (12.5 mg/L), while it was two times higher (26.0 mg/L) in the wine fermented by _S. cerevisiae_ Challenge Aroma White. Some recent research demonstrate that the antioxidant capacity of white wine is much more associated with the presence of hydroxy cinnamates than with any other class of wine constituents. Cinnamic acid derivatives represent the major group of white wine phenols and possess remarkable antioxidant capacity [33; 34]. Flavonols are yellow pigments responsible for the color of white wine [13]. White wines are usually made from free running juices, without grape mash, having no contact with the grape skins. For this reason, flavonoids were the least common phenolics in Aurore must and wine. The initial content of these compounds in the must was 1.1 mg/L, and it decreased in all tested variants during Aurore wine production. The final wine contained 0.4 to 1.0 mg/L of flavonoids. Statistical analysis revealed no significant changes (\(p>0.05\)) depending on the fermentation temperature or yeast strain. Flavonols are located in the peel of the grapes and their higher concentrations are observed in red wines as they are subjected to the process of peel maceration. The concentration of flavonoids in white wine increases during skin fermentation and subsequently begins to decrease as phenols bind with proteins and yeast hulls (cell remnants), and precipitate. During fining, maturation and aging, the concentration of phenolic compounds continues to decrease [26]. Therefore, some modifications of white must maceration are being implemented to increase the content of polyphenic compounds, especially flavonoids in white grape must.