## 4 Discussion
Generally, higher amounts of total phenolic compounds and total anthocyanins in wines produced with both grape varieties was observed when the autochthonous yeast strain F-8 and the commercial yeast strain D-80 were used (Table 5). In fact, the microbial dynamics of specific yeast population under controlled fermentation inevitably results in specific organoleptic and sensory characteristics of the final wines, and such microbial dynamics are dependent on the grape variety [33; 34]. Bitterness and astringency of the produced wines depends on the amount of anthocyanins in grape skin and tannins in grape seeds [35]. The data in this work (Table 5 and Figure 3) showed that grapes from the Vranec variety had a higher amount of anthocyanins in the skins in comparison to the Cabernet Sauvignon grapes. This explains the higher amount of total anthocyanins found in all Vranec wines when compared to the wines from the Cabernet Sauvignon grapes, both of which were produced under the same winemaking conditions. However, the highest amount of total phenolic compounds (Figure 3) in wines from both grape varieties were obtained when the fermentation was undertaken by the commercial yeast strain D-80. The commercial yeast strain D-80 isolated from the Cote Rotie area of the Rhone Valley is claimed to have advantageous phenotype characteristics to ferment polyphenol-rich red musts and it is one of the preferred strains for contributing to the high tannin content (Lallemand Oenology Inc., Vienna, Austria) [36]. The importance of tannins derives from its contribution to the organoleptic characteristics such as astringency [37]. In general, tannin activity is primarily driven by its molecular size. In fact, based on the different maceration times applied, many studies have revealed that increases in the perceived astringency quality are related to the tannin chemistry (i.e., it is driven by tannin molecular mass), as opposed to the tannin pigmentation formation or oxidation effect [34]. Moreover, inter- and intramolecular co-pigmentation of anthocyanins and colorless co-pigments can significantly change the overall color and intensity of red wines [38]. Results from our study confirmed such conclusions. Although Vranec wines V1 and V3 contained the highest amount of total anthocyanins (Table 5), the intensity of the color was remarkable for Cabernet Sauvignon wines CS1 and CS3. The anthocyanin composition in red wines depends not only on the original anthocyanin profile in grape berries, but also on the enological techniques applied [39]. The yeast behavior can modify the phenolic content of red wines by their ability to absorb the phenolic compounds on the yeast cell walls [40]. Moreover, absorption of the phenolic compounds on the yeast cell during fermentation can result in the loss of wine color [41; 42]. Results from our study (Figure 3) indicated that the highest value for color intensity of Vranec wines V1 and V3 fermented by yeast strains F-8 and D-80, respectively, as well as the Cabernet Sauvignon wine CS3 fermented by yeast strain D-80. Such a behavior led us to show that isolated autochthonous yeast strains do not always meet all the desired phenotype traits for winemaking but, important to mention, they contribute effectively to the biodiversity and microbial heritage, which can be very useful to develop and improve new and successful fermentation processes toward the innovation, diversity, and authenticity of wines [43; 44; 45; 46]. The existence of yeast strains with superior genetic traits and technological potential can be achieved through the exploitation of the variety of grape and optimization of the fermentation conditions. Thus, the continuous microbial prospection of yeast strains in natural sources (grapes) from different varieties and from different geographical regions is essential in such a direction.