## 3 Results and Discussion
### Tocopherols  
Tocopherols are lipid-soluble compounds synthesized exclusively by plants, and they play a crucial role in protecting biological membranes and oils from oxidative degradation. In VOO, \(\alpha\)-tocopherol is the predominant isoform, typically representing more than 95% of the total tocopherol content. The concentration of tocopherols in olive fruits appears to be primarily determined by genetic and agronomic factors, rather than by technological or processing conditions. Table 3 presents the concentrations of the tocopherol isoforms detected in the VOO samples extracted using a laboratory-scale Abencor system with and without the application of FTT. The control oils illustrate clear varietal differences: Istarska Bjelica exhibited markedly lower \(\alpha\)-tocopherol concentrations compared to Levantinka and Oblica. Previous studies have reported \(\alpha\)-tocopherol levels in Istarska Bjelica ranging from 89 to 96 mg/kg [(81; 82; 83)]. In the current study, \(\alpha\)-tocopherol levels in Istarska Bjelica were even lower than this published range. Additionally, \(\gamma\)-tocopherol was not detected in this variety. The Levantinka control sample contained 273 mg/kg of \(\alpha\)-tocopherol, consistent with previously reported values [(84)]. Similarly, the tocopherol concentration in the Oblica control sample aligns with data published by [PERSON] et al. [(84)] and [PERSON] et al. [(85)]. Each olive variety exhibited a distinct response to FTT across the range of applied temperatures. In Istarska Bjelica, no statistically significant differences intocopherol content were observed between the control and treated samples, regardless of whether the pretreatment involved cooling or heating. The tocopherols appeared to remain stable under thermal stress, likely due to the synergistic action of oleacein, which has been shown to effectively regenerate \(\alpha\)-tocopherol by reducing the \(\alpha\)-tocopherol radical [86]. All Istarska Bjelica oil samples, irrespective of FTT temperature, contained high concentrations of oleacein (Table 2), which may contribute to the preservation of tocopherols. In contrast, the Levantinka variety, which also contains significant concentrations of oleacein, showed a statistically significant decrease in \(\alpha\)-tocopherol content after cooling to 15 \({}^{\circ}\)C and 20 \({}^{\circ}\)C and after heating to 35 \({}^{\circ}\)C and 40 \({}^{\circ}\)C (the observed decreases were in the range from 13 to 15%). Considering that the oils of Istarska Bjelica contained 2.4 times more total phenols than that of Levantinka, it is very likely that not only oleacein, but also other phenolic substances in the olive paste protected tocopherols from oxidation during malaxation. In contrast to Levantinka, cooling pretreatment did not cause a reduction in \(\alpha\)-tocopherol in Oblica oils, while decline under heating pretreatment at 35 \({}^{\circ}\)C and 40 \({}^{\circ}\)C compared to control was stronger than in Levantinka samples (it ranged from 23% to 24%). The observed decline in tocopherol content is likely attributable to its role as an antioxidant, \begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{**Sample**} & \multicolumn{2}{c}{**Tocopherols**} \\  & \multicolumn{2}{c}{**(mg/kg)**} \\ \cline{2-3}  & **\(\alpha\)-Tocopherol \({}^{*}\)** & \(\gamma\)-Tocopherol \({}^{*}\) \\ \hline Istarska Bjelica & \(p\leq 0.05\) & **\(\ast\ast\)** \\ \hline Control & \(75\pm 4\) a & nd \\  
\hline \hline \end{tabular} nd—not detected; \({}^{*}\) variety had a significant effect (\(p\leq 0.05\)); ** no variance between results and \(p\)-value not computed; presented \(p\)-values indicate the effect of temperature within each variety. Where significant (\(p\leq 0.05\)), [PERSON]’s multiple comparison test was conducted and different letters within column subsections indicate significant differences. All values are mean \(\pm\) standard deviation of three consecutive production batches.  
\end{table}