## 4 Conclusions  
The objective of this study was to evaluate the impact of flash thermal pretreatment of olive paste prior to malaxation on the oxidative stability and antioxidant capacity of VOO derived from three Croatian indigenous olive varieties. Each variety exhibited a distinct response to FTT, applied through both heating and cooling, which manifested in changes in the chemical profile of the resulting VOO. Among the tested varieties, Istarska Bjelica demonstrated the highest resistance to oxidative degradation. OSI increased under both heating and cooling conditions relative to the untreated control, with a statistically significant enhancement at 40 \({}^{\circ}\)C corresponding to a 16% increase in induction time. The antioxidant capacity of this variety remained unaffected by all thermal treatments. The improvement in IP and robustness of AC is primarily attributed to the highest concentrations of phenolic compounds, which were identified as the most important factors for OSI and AC via PLS regression analysis. In contrast, VOO obtained from the Oblica variety was most susceptible to oxidative deterioration. FTT via heating resulted in a pronounced reduction in OSI (23-28%) and a decline in AC (12-28%) across all treatment temperatures, except 20 \({}^{\circ}\)C. \(\alpha\)-tocopherol  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{3}{*}{**Variety**} & & \multicolumn{5}{c}{**Parameters for Optimization**} \\ \cline{3-8}  & & \multicolumn{1}{c}{**IP**} & \multicolumn{1}{c}{**AC**} & \multicolumn{1}{c}{**\(\Sigma\) LOX**} & \multicolumn{1}{c}{**\(\Sigma\) OX**} & \multicolumn{1}{c}{**\(\Sigma\) MBA**} \\  & & \multicolumn{1}{c}{**min**} & \multicolumn{1}{c}{**(\% DPPH Red. )**} & \multicolumn{1}{c}{**mg/kg**} & \multicolumn{1}{c}{**mg/kg**} & \multicolumn{1}{c}{**mg/kg**} \\ \cline{2-8}  & \multicolumn{3}{c}{**Model \({}^{\star}\)**} & \multicolumn{3}{c}{**y = a + b \(\times\) T + c \(\times\) T\({}^{2}\) + d \(\times\) T\({}^{3}\)**} & \\ \hline \multirow{8}{*}{Istarska Bjelica *} & a & 237.017 & 54.088 & 5.761 & \(-\)1.755 & \(-\)0.593 \\  & b & \(-\)3.128 & 0.484 & 1.549 & 0.264 & 0.059 \\  & c & 0.065 & \(-\)0.009 & 0.029 & \(-\)0.004 & \(-\)0.001 \\  & \multirow{2}{*}{\(p\)-Value} & Model & 0.035 & 0.362 & 0.210 & 0.146 & 0.040 \\  & & Lack of fit & 0.056 & 0.338 & 0.001 & 0.007 & \(<\)0.0001 \\  & & R\({}^{2}\) & 0.361 & 0.127 & 0.189 & 0.227 & 0.350 \\  & \multirow{2}{*}{Optimal temperature} & \multicolumn{5}{c}{18.9} \\  & \multicolumn{1}{c}{Desirability} & \multicolumn{1}{c}{0.481} \\  & Predicted values & 201 & 60.80 & 24.56 & 1.51 & 0.07 \\ \hline \multirow{8}{*}{Levantinka \({}^{\star}\)} & a & 119.932 & 62.511 & 39.282 & 3.009 & \(-\)0.133 \\  & b & 2.705 & \(-\)1.096 & 0.249 & 0.004 & 0.012 \\  & c & \(-\)0.047 & 0.021 & \(-\)0.005 & \(-\)2.98 \(\times\) 10\({}^{-5}\) & \(-\)1.54 \(\times\) 10\({}^{-4}\) \\ \cline{1-1}  
and \(\gamma\)-tocopherol levels were significantly diminished under both heating and cooling conditions. Heating treatments notably reduced the total content of ligstroside aglycones (by 30-68%) and \(p\)-coumaric acid (by 16-25%), phenolic compounds relevant to OSI and AC. This variety also exhibited the lowest MUFA (\(\sim\)70%) and highest PUFA (\(\sim\)12%) levels among the three. However, thermal pretreatment at 30, 35, and 40 \({}^{\circ}\)C led to a marked increase in the concentrations of olacein (1.9-2.8 times relative to control) and oleocanthal (1.6-2 times). Levantinka exhibited intermediate sensitivity. A decrease in OSI and AC was also observed after FTT, but the Levantinka has a longer IP than the Oblica, and the decrease in AC (11%) was only pronounced at 25 \({}^{\circ}\)C. Although it has the lowest concentration of phenolic compounds compared to the other two varieties, Lavantinka is characterized by the highest MUFA and the lowest PUFA levels.