# Varietal Authentication of Extra Virgin Olive Oils by Triacylglycerlycerols and Volatiles Analysis
## Results and Discussion
### Volatile Fraction  
In this investigation SPME-GC-MS, a simple and effective analytical method, was performed to obtain qualitative and semi-quantitative profiles of volatiles from EVOO samples. Figure 1 shows the chromatographic profile of the volatile compounds of a monovarietal EVOO (Dolce Agogia) sample. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**FA** & **Dolce Agogia** & **Frantoio** & **Leccino** & **Moraiolo** \\ \hline \multicolumn{5}{c}{_sn_-1} \\ \hline C16:0 & 15.4 \(\pm\) 1.9 & 18.6 \(\pm\) 1.7 & 17.5 \(\pm\) 1.2 & 17.6 \(\pm\) 1.6 \\ C16:1 (_n_-9 + _n-7_) & 1.1 \(\pm\) 0.3 & 1.2 \(\pm\) 0.5 & 1.2 \(\pm\) 0.2 & 1.0 \(\pm\) 0.2 \\ C18:0 & 3.2 \(\pm\) 0.5 & 2.8 \(\pm\) 0.6 & 3.3 \(\pm\) 0.7 & 3.0 \(\pm\) 0.6 \\ C18:1 (_n_-9 + _n-7_) & 73.1 \(\pm\) 2.9 & 69.2 \(\pm\) 2.9 & 69.4 \(\pm\) 2.9 & 70.0 \(\pm\) 2.4 \\ C18:2 _n_-6 & 6.7 \(\pm\) 0.6 & 7.7 \(\pm\) 0.7 & 8.0 \(\pm\) 0.5 & 7.8 \(\pm\) 0.7 \\ C18:3 _n_-3 & 0.5 \(\pm\) 0.0 & 0.5 \(\pm\) 0.2 & 0.6 \(\pm\) 0.0 & 0.6 \(\pm\) 0.1 \\ \hline \multicolumn{5}{c}{_sn_-2} \\ \hline C16:0 & 0.4 \(\pm\) 0.1 & 0.6 \(\pm\) 0.1 & 0.5 \(\pm\) 0.1 & 0.6 \(\pm\) 0.1 \\ C16:1 (_n_-9 + _n-7_) & 0.5 \(\pm\) 0.1 & 0.6 \(\pm\) 0.1 & 0.7 \(\pm\) 0.1 & 0.7 \(\pm\) 0.1 \\ C18:0 & - & 0.1 \(\pm\) 0.0 & 0.1 \(\pm\) 0.0 & - \\ C18:1 (_n_-9 + _n-7_) & 89.1 \(\pm\) 2.3 & 87.2 \(\pm\) 2.1 & 86.8 \(\pm\) 2.4 & 87.8 \(\pm\) 1.9 \\ C18:2 _n_-6 & 8.9 \(\pm\) 1.5 & 10.5 \(\pm\) 1.8 & 10.8 \(\pm\) 2.0 & 10.0 \(\pm\) 1.6 \\ C18:3 _n_-3 & 1.1 \(\pm\) 0.2 & 1.0 \(\pm\) 0.1 & 1.1 \(\pm\) 0.0 & 0.9 \(\pm\) 0.1 \\ \hline \multicolumn{5}{c}{_sn_-3} \\ \hline C16:0 & 21.2 \(\pm\) 2.6 & 17.9 \(\pm\) 3.0 & 21.7 \(\pm\) 1.1 & 20.7 \(\pm\) 2.5 \\ C16:1 (_n_-9 + _n-7_) & 1.2 \(\pm\) 0.5 & 0.5 \(\pm\) 0.2 & 0.9 \(\pm\) 0.3 & 0.9 \(\pm\) 0.2 \\ C18:0 & 3.1 \(\pm\) 0.8 & 2.9 \(\pm\) 1.3 & 2.8 \(\pm\) 1.8 & 3.0 \(\pm\) 0.7 \\ C18:1 (_n_-9 + _n-7_) & 71.8 \(\pm\) 3.1 & 74.9 \(\pm\) 4.8 & 71.9 \(\pm\) 2.4 & 71.5 \(\pm\) 2.7 \\ C18:2 _n_-6 & 2.1 \(\pm\) 0.3 & 3.2 \(\pm\) 0.7 & 2.3 \(\pm\) 1.0 & 3.0 \(\pm\) 1.0 \\ C18:3 _n_-3 & 0.6 \(\pm\) 0.1 & 0.6 \(\pm\) 0.3 & 0.4 \(\pm\) 0.1 & 0.9 \(\pm\) 0.5 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Intrapositional FA percent composition of TAG fraction of monovarietal EVOO samples (% mol, mean values \(\pm\) SD, \(n\) = 3). The semi-quantitative results (% areas) of the considered EVOO samples are shown in Table 3.  
Some differences have been highlighted among the cultivars, both as regards the percent content of the _trans_-2-hexenal, the compound most represented in all cultivars, and other minor components. The _trans_-2-hexenal, which is formed from the \(\alpha\)-linolenic acid by the action of the lipoxygenase enzymes, hydroperoxide lyase and isomerase, has been found in less amounts in the Moraiolo cultivar with respect to the Franttoio variety (\(p<0.01\)), and also to Leccino and Dolce Agogia (\(p<0.01\)). The content of this unsaturated aldehyde was also significantly different between Dolce Agogia - Franttoio (\(p<0.01\)) and Leccino (\(p<0.05\)) varieties. Other observations regard the percent content of the _trans_-2-hexen-1-ol. This compound is obtained from the _trans_-2-hexenal by alcohol dehydrogenase activity, and its contents show an opposite trend with respect to its precursor (_trans_-2-hexenal). It was more represented in Moraiolo variety, followed by Dolce Agogia, Leccino and Franttoio. The differences between the cultivars are also enhanced if the relationship between the two compounds was considered. Based  
Figure 1: High-resolution gas chromatography mass-spectrometry (HRGC-MS) profile of volatile fraction of a monovarietal EVOO (Dolce Agogia) sample. Peak numbers correspond to the compounds listed in Table 3.