## 3 Results
#### 3.1.3 Main Volatile Compounds
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **OKAY\({}^{\text{\textregistered}}\) + SO\({}_{2}\)** & **OKAY\({}^{\text{\textregistered}}\)** & _S. cerevisiae_ DiSVA & _S. cerevisiae_ DiSVA 709 + SO\({}_{2}\) & _T. delbrueckii_ \\  & & & **709** & **709** & **709** \\ \hline \hline
**ESTERS** & & & & & \\ \hline Ethly butyrate & & & & & \\ (0.02) & 1.214 \(\pm\) 0.021 \({}^{\text{b}}\) & 1.491 \(\pm\) 0.075 \({}^{\text{a}}\) & 0.653 \(\pm\) 0.223 \({}^{\text{c}}\) & 0.628 \(\pm\) 0.035 \({}^{\text{c}}\) & 0.208 \(\pm\) 0.011 \({}^{\text{d}}\) & 0.441 \(\pm\) 0.084 \({}^{\text{d}}\) \\ Ethyl acetate & & & & & \\ (7.50) & & & & & \\ hexanoic & 1.063 \(\pm\) 0.2354 \({}^{\text{a}}\) & 0.16 \(\pm\) 0.0017 \({}^{\text{b}}\) & 0.253 \(\pm\) 0.0974 \({}^{\text{b}}\) & 0.191 \(\pm\) 0.0110 \({}^{\text{b}}\) & 0.081 \(\pm\) 0.0149 \({}^{\text{b}}\) & 0.161 \(\pm\) 0.064 \({}^{\text{b}}\) \\ Isoamyl acetate & & & & & \\ (0.03) & & & & & \\ Phenyl ethyl acetate & & & & & \\ (0.25) & 0.31 \(\pm\) 0.01 \({}^{\text{b}}\) & 0.27 \(\pm\) 0.04 \({}^{\text{b}}\) & 0.64 \(\pm\) 0.01 \({}^{\text{a}}\) & 0.76 \(\pm\) 0.04 \({}^{\text{a}}\) & 0.63 \(\pm\) 0.13 \({}^{\text{a}}\) & 0.79 \(\pm\) 0.19 \({}^{\text{a}}\) \\ \hline
**ALCOHOLS** & & & & & \\ (0.0) & & & & & \\ (40.0) & & & & & \\ Amyl alcohol & & & & & \\ (2.2) & 12.601 \(\pm\) 2.27 \({}^{\text{b}}\) & 12.245 \(\pm\) 1.51 \({}^{\text{c}}\) & 19.211 \(\pm\) 0.51 \({}^{\text{c}}\) & 14.909\(\pm\) 0.08 \({}^{\text{b}}\) & 20.74 \(\pm\) 1.50 \({}^{\text{a}}\) & 25.690 \(\pm\) 0.92 \({}^{\text{a}}\) \\ Isoamyl alcohol & & & & & \\ (30.0) & & & & & \\ (3.9)-Phenyl ethanol & & & & & \\ (14.0) & & & & & \\ \hline
**CARBONYL COMPOUNDS** & & & & & \\ \hline Acetaldehyde & & & & & \\ (0.5) & 6.40 \(\pm\) 2.83 \({}^{\text{d}}\) & 3.23 \(\pm\) 0.15 \({}^{\text{b}}\) & 8.22 \(\pm\) 0.31 \({}^{\text{a}}\) & 7.70 \(\pm\) 1.85 \({}^{\text{a}}\) & 4.79 \(\pm\) 0.50 \({}^{\text{d}}\) & 3.02 \(\pm\) 0.68 \({}^{\text{b}}\) \\ \hline
**TERPENS** & & & & & \\ \hline Linalool & & & & & \\ (0.025) & & & & & \\ Germanid & & & & & \\ (0.030) & & & & & \\ Nerol (0.025) & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The main volatile compounds of _T. delbrueckii_ in sequential fermentation as compared with pure fermentation of _S. cerevisiae_ starter strain (mg/L). The threshold values are reported in brackets (mg/L). Data are the means \(\pm\) standard deviation. Data with different superscript letters (a,b,c,d) within each column are significantly different (Duncan tests; \(p<0.05\)). significantly reduced this increase. Moreover, the sequential fermentation of _T. delbrueckii/S. cerevisiae_ DiSVA 709 showed a significant enhancement in ethyl butyrate, \(\beta\)-phenyl ethanol, and geraniol in the trials without SO\({}_{2}\) added, while in the same condition, a significant increase in ethyl acetate was found in pure cultures of _S. cerevisiae_ (DiSVA 709 and OKAY(r)). The sequential fermentation trials showed the highest amounts of higher alcohols (except for n-propanol) and isomyl acetate, while there were no substantial differences in terpene production. The oenological features of the OKAY(r) strain were confirmed by [PERSON] and colleagues [21], demonstrating the highest production of ethyl butyrate and n-propanol and lower production of phenylethyl acetate. Second Set of Fermentation Trials: Evaluation and Comparison of Native T. delbrueckii DiSVA 130 and Commercial Strain ALPHA(r) in Sequential Fermentation with S. cerevisiae DiSVA 709 (No SO\({}_{2}\) Added)  
The results from the first set of fermentations established that sequential fermentations ensured effective wild yeast control in the absence of sulfites. In these trials, with no SO\({}_{2}\) added, the native strain _T. delbrueckii_ DiSVA 130 was compared with a commercial strain, _T. delbrueckii_ ALPHA(r), in combination with native _S. cerevisiae_ DiSVA 709.