## 3 Results
### Genological Characterization of Predominant Native _S. cerevisiae_ Isolated Strains
#### 3.3.2 Analytical Characteristics  
The main oenological characteristics of wines carried out at 16 \({}^{\circ}\)C are reported in Table 3. The results obtained show that biotype I exhibited the significant lowest value of all parameters tested apart from volatile acidity that was significantly higher than that shown by the other strains. Regarding the ethanol content, biotype I showed the highest value of 12.31% \(v/v\), comparable with those produced by the starters OKAY and EC1118, while biotype II revealed the lowest ethanol content. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Sampling Year**} & \multicolumn{2}{c}{**Number of**} & \multicolumn{2}{c}{**Origin of Sampling**} & \multicolumn{2}{c}{**Total of Yeast for Each Biotype**} \\  & **Isolates** & **Bioptype** & **Grape** & **Winery Environment** & **Wine Fermentation** & **Total of Yeast for Each Biotype** \\ \hline \multirow{6}{*}{2016} & \multirow{6}{*}{43} & I & 6 (14\%) & 12 (28\%) & 11 (26\%) & 29 (48\%) \\  & & II & 7 (\%) & 1 (2\%) & 7 (16\%) & 8 (19\%) \\  & & III & 2 (8\%) & / & / & 2 (5\%) \\  & & IV & 1 (2\%) & / & / & 1 (2\%) \\  & & V & / & / & 1 (2\%) & 1 (2\%) \\  & & VI & 1 (2\%) & / & / & 1 (2\%) \\  & & VII & / & / & 1 (2\%) & 1 (2\%) \\  & & VIII & / & / & / & / \\  & & IX & / & / & / & / \\ \hline \multirow{6}{*}{2019} & \multirow{6}{*}{55} & I & 13 (24\%) & 5 (9\%) & 6 (11\%) & 24 (43\%) \\  & & II & 13 (2\%) & 3 (5\%) & 7 (13\%) & 23 (42\%) \\  & & III & 1 (2\%) & / & 2 (4\%) & 3 (5\%) \\  & & IV & / & / & 1 (2\%) & 1 (2\%) \\  & & V & / & / & 2 (4\%) & 2 (4\%) \\  & & VI & / & / & / & / \\  & & VII & / & / & / & 1 (2\%) \\  & & IX & / & / & 1 (2\%) & 1 (2\%) \\ \hline \multirow{6}{*}{2016/2019} & \multirow{6}{*}{98} & I & 19 (19\%) & 17 (17\%) & 17 (17\%) & 53 (54\%) \\  & & II & 13 (13\%) & 4 (4\%) & 14 (14\%) & 31 (2\%) \\  & & III & 3 (30\%) & / & 2 (2\%) & 5 (5\%) \\  & & IV & 1 (1\%) & / & 1 (1\%) & 2 (2\%) \\  & & V & / & / & 3 (3\%) & 3 (3\%) \\  & & VI & 1 (1\%) & / & / & 1 (1\%) \\  & & VII & / & / & 1 (1\%) & 1 (1\%) \\  & & IX & / & / & 1 (1\%) & 1 (1\%) \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Occurrence of 5. cerevisiae biotypes in different years and samples. Percentage values were calculated on the basis of the number of isolates of the same year. For both viruses (2016/2019), the percentage values were calculated considering the sum of the isolates of both sampling years. 1 No presence of 5. cerevisiae. Furthermore, biotype II exhibited a significant increase in acetaldehyde and total SO\({}_{2}\) content in comparison with the other strains tested. Among the _S. cerevisiae_ starter strains, VIN13 exhibited a significantly higher fermentation rate (g CO\({}_{2}\)/day over the 3 rd day of fermentation) and free amino acid content in comparison with other fermentation trials. The results of the main analytical characters of the fermentation carried out at 22 \({}^{\circ}\)C are reported in Table 4. The data obtained show a different trend from those obtained at 16 \({}^{\circ}\)C (Table 3). Indeed, the fermentation rate did not display significant differences among the strains tested, with the only exception being the _S. cerevisiae_ starter strain OKAY(r) that showed a significantly lower fermentation rate. About other characteristics, significant differences were found. The commercial starter strains VIN13 and OKAY(r) showed a significant increase in volatile acidity. Total SO\({}_{2}\) was significantly higher in biotype II confirming the behavior shown at 16 \({}^{\circ}\)C. All fermentation led to a low acetaldehyde content with the only exception being VIN13 that showed the highest value, but it was below the threshold. The value of free \(\alpha\)-amino acids was generally comparable among the strains tested. The same ethanol content was detected at 22 and 16 \({}^{\circ}\)C for biotype I with slight variations for the OKAY and VIN13 starters. Conversely, biotype II as well as the starter  
Figure 1: Fermentation kinetic of _S.