## 4 Discussion
Most \(\beta\)-glucosidase activities are susceptible to feedback inhibition by the product and require a high enzyme load to achieve a certain hydrolysis efficiency, which increases the cost of production [22]. Therefore, we assessed the impact of different sugars on the activity of these enzymes. The selected sugars showed activating effects on both Mg-\(\beta\)gl and Hu-\(\beta\)gl, especially cellobiose, which showed a significant activation. This is very beneficial to improve the hydrolysis efficiency of \(\beta\)-glucosidase. Additionally, Mg-\(\beta\)gl and Hu-\(\beta\)gl showed better tolerance to ethanol than most reported \(\beta\)-glucosidase of non-_Saccharomyces_ yeast origin [9; 42]. From some reported research, it appears that the alteration of some residues and the presence of specific motifs in the amino acid sequence could improve the tolerance of \(\beta\)-glucosidase to ethanol [43]. However, further investigation on the structure of the enzyme is needed to help researchers better understand this phenomenon. During wine aging, the release of volatile compounds from their glycosides by acid catalysis is rather slow, except for the glycosides of allyl alcohol [44]. In contrast, exogenous glycosylades enable the rapid release of glycosides from sugar conjugates, which, due to the reactivity of the released glycosides in the wine pH, contributes to the accelerated synthesis of active compounds with volatile aromas during wine aging [44]. It has been reported that enzymatic treatment of wines followed by short-term bottle aging can help improve the aroma of wines [45], which is similar to the results of the present study. The results of this study showed that the use of Mg-\(\beta\)gl, Hu-\(\beta\)gl, and An-\(\beta\)gl in aging increased the total concentration of terpen and C\({}_{13}\)-norisoprenoids. [PERSON] et al. [46] also reported an increase in the total concentration of terpenes and C\({}_{13}\)-norisoprenoids with the use of \(\beta\)-glucosidaseidase at the end of alcoholic fermentation. Interestingly, \(\beta\)-glucosidaseidase from \(M\). _guillieromodii_ NM218 and \(H\). _uratum_ BF345 strongly increased the concentration of linalool compared to the control, whereas commercial \(\beta\)-glucosidaseidase from \(A\). _niger_ showed an insignificant increment of linalool. This is in contrast to [PERSON] et al. [47], who observed that treatment of Chardonnay wines with a commercial enzyme (AR-2000) increased linalool content by 64.2%. This suggests that \(\beta\)-glucosidaseases of different origins have different acting substrates and were more or less strongly influenced by the nature of the glycosidic elements [48]. In addition, geraniol was not detected in Mg-\(\beta\)gl- and Hu-\(\beta\)gl-treated wines, but it was detected in An-\(\beta\)gl-treated wines. However, its concentration did not exceed the odor perception threshold (OAV < 1), a result that can be attributed to the presence of a small number of precursors in this wine. Meanwhile, this study found that C\({}_{13}\)-norisoprenoids were detected only in enzymatically treated wines. [PERSON] et al. also reported that enzyme treatment increased C\({}_{13}\)-norisoprenoids concentrations from 265 to 2000% [49]. C\({}_{13}\)-norisoprenoids are mainly glycosylated in grapes, and unlike terpen, they are present in nearly equal amounts in all varieties. Because they have a lower odor threshold than terpenes, they can provide aromatic characteristics that confer certain typicality to wine flavors when hydrolyzed [49; 50]. C\({}_{6}\) compounds detected in wines generally impart raw green or herbal flavors to wines [31], but high concentrations of C\({}_{6}\) compounds above their thresholds impart undesirable grassy flavors to wines [51]. In this study, none of the C\({}_{6}\) compounds detected exceeded their odor thresholds. Notably, hexanol showed the highest concentration in Mg-\(\beta\)gl- and Hu-\(\beta\)gl-treated wines, which reveals the important role of \(\beta\)-glucosidase in the hydrolysis of hexanol precursors.