## 3 Results and Discussion
### Volatile Composition
cerevisiae_ which provide certain aromatic deviations in cavas, unlike other non-_Saccharomyces_ yeasts which do not produce them. The Xarel.lo cavas presented the highest concentrations of acetates with the three yeasts Y1, Y2, and Y5. These high values were mainly due to the isoamyl acetate compound, with values well above its sensory limit (670 \(\upmu\)g/L) [32]. This could give the cavas a marked tropical aromatic profile because banana is their main aromatic descriptor. In addition, in cavas with Y2 and Y5, higher concentrations of isoamyl acetate and 2-phenylethylly acetate were observed. All of these results show that the yeast _T. delbrueckii_ (Y5) is also capable of providing a more marked tropical character in cavas, unlike others in which only _Saccharomyces_ yeasts were used. Regarding aromatic alcohols, a different trend between the two grape varieties was observed. Whereas Xarel.lo presented a slight decrease in alcohol concentrations during aging, the Chardonnay variety showed a slight increase in the concentration of alcohol. However, despite these different trends, after 18 months of aging on lees, it was observed that both varieties present similar values of total alcohols, with a concentration range between 4964 and 6353 \(\upmu\)g/L. In reference to the analyses of alcohols in Chardonnay BW, all of the base wines presented similar values, obtaining the highest value with yeast Y4 and the lowest concentration with Y2. For the Xarel.lo variety, the high concentrations of alcohols produced by Y3 and Y4 yeasts stand out. These high values were mainly due to two of the studied compounds: isoamyl alcohol and 2-phenylethylly alcohol. These compounds provide floral aromas of roses, pollen, and perfume [1; 34]. Regarding the 18M time, in the Chardonnay variety, the cava obtained with Y2 had the highest concentration followed by Y5, Y3, and Y1. This is mainly due to the obtained concentrations of the isoamyl alcohol compound (Table 3). In XA, all of the cavas generally presented similar values, with the exception of the cava with yeast Y5, which presented a slightly lower value. Therefore, with respect to the chemical family of alcohols, it could be noted that the yeast _M. pulcherrina_ (Y4) implied the highest alcohol content of BW but, after aging on lees, these values were generally similar to those obtained by the _Saccharomyces_ yeasts, as observed in the XA variety. Finally, in the family of fatty acids, the cava obtained with the Y3 yeast presented the lowest concentrations of fatty acids (in all studied cases), with significant differences compared to the other yeasts. In Chardonnay, four base wines presented similar values (Y1, Y2, Y4, Y5). However, for the Xarel.lo variety, the highest concentrations of fatty acids obtained when using Y2 and Y5 stood out. It should be noted that _T. delbrueckii_ (Y5) presented the highest fatty acid values. These high values were mainly due to the concentrations obtained for hexanoic acid and octanoic acid (Table 3). These compounds give aromas of soap, cheese, and yogurt (Table S2). By comparison, after 18 months of aging on the lees, the cava with the Y2 yeast presented the highest concentrations of fatty acids in both varieties. However, it could be noted that non-_Saccharomyces_ yeasts (Y4 and Y5) presented similar or higher values than those produced by other _Saccharomyces_ yeasts (Y1 and Y3).