## 3 Results
### Effect of PEF Technology on the Volatile Composition of VOO  
Although there are obvious differences between the volatile profiles of different olive cultivars--and even within the oils of the same olive cultivar but from different harvesting seasons--the data obtained reveal some modifications that seem to be associated with the application of PEF technology on olive pastes (Table S1). Probably the most important modification is that all PEF-treated oils, except for 'Manzanilla' oils in the second trial, always have higher (_E_)-hex-2-enal contents than their corresponding controls (Table S1). This data is quite relevant given that this compound is qualitatively and quantitatively the most important component for the aroma of VOO due to its high concentration in most olive oils and its relatively low odor threshold [32]. In most of the PEF oils, significantly higher contents of C6/LA aldehydes and some C5 compounds were also found. The aroma of VOO is made up of a complex mixture of volatile compounds, in which aldehydes and alcohols with 5 (C5) and 6 (C6) carbon atoms and their corresponding esters formed through the LOX pathway stand out [10]. The LOX pathway begins with the release of linoleic and linelenic acids that are part of the cell membranes, and it is triggered by the crushing of the olive tissue. Thus, it seems reasonable that the application of the PEF treatment immediately after the milling step could increase plant cell disruption and enhance the formation of volatiles through the LOX pathway. In previous studies in which PEF technology was applied after the malaxation stage, when the LOX pathway is no longer active, no significant changes in the volatile composition of the oils have been observed [28]. On the contrary, [PERSON] et al. [18] also detected changes in the volatile composition of VOO when PEF technology was applied immediately after milling, before the malaxation stage. As previously described for phenolic compounds, we have evaluated the effect of PEF technology on the volatile composition of oils at different malaxation times. Figure 1C shows the content of (_E_)-hex-2-enal in control and PEF oils (cultivar 'Manzanilla') as a function of the malaxation time. As in the case of phenolics, the differences between both oils were greater the shorter the malaxation time. Thus, the content of (_E_)-hex-2-enal in PEF oils reached its maximum at time 0, while in control oils the content of this key volatile component increased steadily and reached its maximum concentration after 45 min. These data suggest that PEF technology would allow a more efficient and faster biosynthesis of this compound and/or absorption of this compound by the recently \begin{table}
\begin{tabular}{l c c c c c} \hline \hline \multicolumn{2}{c}{**Tocopherols (mg kg\({}^{-1}\))**} & \(\boldsymbol{\alpha}\)**-toc** & \(\boldsymbol{\beta}\)**-toc** & \(\boldsymbol{\gamma}\)**-toc** & **Total** \\ \hline
1 st pilot tests & Manzanilla Control & 152.50 \(\pm\) 0.17 & 1.40 \(\pm\) 0.00 & 9.10 \(\pm\) 0.16 & 163.00 \(\pm\) 2.60 \\  & Manzanilla PEF & 153.10 \(\pm\) 0.02 & 1.60 \(\pm\) 0.00 & 9.20 \(\pm\) 0.01 & 164.00 \(\pm\) 1.90 \\
2 nd pilot tests & Manzanilla Control & 185.50 \(\pm\) 0.28 & 1.80 \(\pm\) 0.00 & 10.10 \(\pm\) 0.80 & 199.90 \(\pm\) 1.70 \\  & Manzanilla PEF & 187.50 \(\pm\) 0.09 & 1.80 \(\pm\) 0.00 & 10.00 \(\pm\) 0.08 & 199.30 \(\pm\) 0.40 \\
3 rd pilot tests & Hoijblanca Control & 303.00 \(\pm\) 0.21 & 4.10 \(\pm\) 0.00 & 12.50 \(\pm\) 0.19 & 319.50 \(\pm\) 0.90 \\  & Hoijblanca PEF & 304.40 \(\pm\) 0.12 & 4.10 \(\pm\) 0.00 & 12.80 \(\pm\) 0.02 & 321.30 \(\pm\) 0.80 \\ Industrial tests & Manzanilla Control & 131.57 \(\pm\) 0.05 & 1.00 \(\pm\) 0.00 & 21.32 \(\pm\) 0.32 & 154.92 \(\pm\) 1.80 \\  & Manzanilla PEF & 133.79 \(\pm\) 0.01 & 1.00 \(\pm\) 0.00 & 22.14 \(\pm\) 0.32 & 157.46 \(\pm\) 1.14 \\ \hline \hline \end{tabular} Results are expressed as means \(\pm\) SD (_n_ = 3).  
\end{table} 
Table 6: Tocopherols content (mg kg\({}^{-1}\)) in control and PEF oils obtained from ‘Manzanilla’ and ‘Hojibblanca’ cvs.