# Influence of Microbial Treatments on Vine Growth and Must Quality: Preliminary Results
## 2 Results and Discussion
### Aroma Composition
#### 2.4.2 Pressed Grapes  
The complete volatile emission of the pressed grapes is reported in Table 5. Unlike whole grape berries, these samples were characterized by the presence of lower percentages of ketones, represented only by 2-octanone and 2-nonanone, which were also in this case in higher amounts in control grapes. The most abundant chemical class of the pressed grapes volatile emission was represented by aldehydes, among which the most abundant detected compound was (_E_)-2-hexenal, followed by hexanal. The treatment with mycorrhizal fungi seemed to be able to enhance the biosynthesis of the former compound to the disadvantage of the latter. Besides being associated with more pleasant fruits aroma notes [40] compared to hexanal and exhibiting fresh, green aromas [41]), (_E_)-2-hexenal is also reported to be an important precursor of varietal thiol aroma compounds. Indeed, it is able to react with glutathione, forming the aroma precursor 3-S-glutathionylhexanol [42]. This aspect suggests a probable improvement of the aroma profile of wines obtained from grapes treated with Bioma products. Along with aldehydes, alcohols were also found in relevant amounts, with (_E_)-2-hexen-1-ol and 1-hexanol as key compounds. Analogously to the aldehydes, Bioma treatment seemed to be related to increased production of more (_E_)-2-hexen-1-ol than 1-hexanol and also linked to the production of the unsaturated C6-thiol precursors of key aroma compounds.  
\begin{table}
\begin{tabular}{l c c c c c} \hline \hline \multirow{2}{*}{**Compounds**} & \multirow{2}{*}{**Lri. 1**} & \multirow{2}{*}{**Class**} & \multicolumn{2}{c}{**Relative Abundance (\%) \(\pm\) Standard Deviation**} & \multirow{2}{*}{**Significance Level**} \\ \cline{3-3} \cline{5-6}  & & & **Control Grapes** & & **Bioma Grapes** \\ \hline
1-Octanol & 1069 & nt & 0.6 \(\pm\) 0.04 \({}^{\text{A}}\) & - \({}^{\text{B}}\) & \({}^{\text{*}}\) \\ \hline
2-Nonanone & 1093 & nt & 5.2 \(\pm\) 0.97 & 5.2 \(\pm\) 0.77 & n.s. \\ \hline Nonanal & 1105 & nt & 2.2 \(\pm\) 0.01 \({}^{\text{A}}\) & 1.1 \(\pm\) 0.22 \({}^{\text{B}}\) & \({}^{\text{*}}\) \\ \hline Methylundecane & 1156 & nt & 0.7 \(\pm\) 0.08 \({}^{\text{B}}\) & 1.4 \(\pm\) 0.07 \({}^{\text{A}}\) & \({}^{\text{*}}\) \\ \hline Dodecane & 1200 & nt & 1.1 \(\pm\) 0.12 \({}^{\text{B}}\) & 3.7 \(\pm\) 0.26 \({}^{\text{A}}\) & \({}^{\text{**}}\) \\ \hline Decanal & 1206 & nt & 2.2 \(\pm\) 0.08 & 1.9 \(\pm\) 0.65 & n.s. \\ \hline
2-Undecanone & 1294 & nt & 0.5 \(\pm\) 0.2 \({}^{\text{B}}\) & 1.6 \(\pm\) 0.19 \({}^{\text{A}}\) & \({}^{\text{**}}\) \\ \hline (_E_)-Geranylacetone & 1453 & ac & 0.6 \(\pm\) 0.13 \({}^{\text{A}}\) & 0.3 \(\pm\) 0.00 \({}^{\text{B}}\) & \({}^{\text{**}}\) \\ \hline Other non-terpene derivatives (nt) & & 98.2 \(\pm\) 0.25 & 94.6 \(\pm\) 0.01 & \({}^{\text{*}}\) \\ Monoterpene hydrocarbons (mh) & & 1.1 \(\pm\) 0.11 & 5.3 \(\pm\) 0 & \({}^{\text{**}}\) \\ Apocartenoids (ac) & & 0.6 \(\pm\) 0.13 & 0.3 \(\pm\) 0 & \({}^{\text{*}}\) \\ \hline Total identified (\%) & & 100 \(\pm\) 0.01 & 100 \(\pm\) 0.01 & \\ \hline \hline \end{tabular}  
* \({}^{\text{A}}\) Linear retention index on a HP 5-MS capillary column; \({}^{\text{B}}\) not detected. Superscript uppercase letters (A–B) indicate statistically significant differences between Bioma and control samples. The asterisks in the “Significant level” column indicates \({}^{\text{*}}\)_p_ \(<\) 0.05, \({}^{\text{**}}\)_p_ \(<\) 0.01, \({}^{\text{***}}\)_p_ \(<\) 0.0001, while n.s. means not significant.  
\end{table}
Table 4: _Cont._