## 3 Results and Discussion
### Oxidative Stability
[41] suggested that triacylglycerglycerols with polyunsaturated fatty acids incorporated in internal positions are more resistant to oxidative degradation and thermal polymerization than triacylglycerglycerols with these acids incorporated in external positions. Oil A1 with the highest content of linoleic acid in the \(sn\)-2 position was characterized by the highest maximum oxidation time, whereas oil A2 had the lowest maximum induction time with the lowest content of linoleic acid in the \(sn\)-2 position. In order to verify the influences of the contents of oleic and polyunsaturated fatty acids on maximum time of oxidation, the [PERSON]'s linear correlations were extrapolated for tested samples in five diverse isothermal temperatures in the range of 100-140 \({}^{\circ}\)C (Table 3). Additionally, mathematical equations were determined. Based on the [PERSON]'s indexes, the strong positive correlation between maximum oxidation time and content of oleic acid in the temperature of oxidation above 120 \({}^{\circ}\)C (Table 3) was noticed. Contrarily, a negative but also strong relationship between polyunsaturated fatty acids and maximum oxidation time was observed. This dependence was exhibited in the temperature range of 120-140 \({}^{\circ}\)C.  
Comparing the oxidative stability of the tested peach and apricot kernel oils with other oils derived from non-typical raw materials, it can be concluded that the A1 and P1 oils were characterized by greater resistance to oxidation than those oils from cranberry seeds, blackcurrant seeds, strawberry seeds, quinone seeds, amaranth seeds, rose hip, and sea buckthorm [40,42,43]. The recorded oxidation time at 120 \({}^{\circ}\)C was 46.09 min for cranberry seed oil, 17.33 min for blackcurrant seed oil, 9.39 min for strawberry seed oil [36], 82.82 min for quinoa seed oil, 112 min for amaranth seed oil [44], 40.58-24.45 min for rose hip oil, and 36.56-17.81 min for sea buckthorm oil [45]. The oxidation time determined at 120 \({}^{\circ}\)C for the analyzed A1 oil was 160.28 min and for P1 oil 118.52 min. Apricot kernel oil A2, with oxidation time 33.74 min at 120 \({}^{\circ}\)C, was characterized by a similar resistance to oxidation as rose hip oil and sea buckthorm oil [45] but was more stable than strawberry seed oil and blackcurrant seed oil [42]. For peach kernel oil P2, similar resistance to oxidation was found as for quinoa seed oil [44]. Oil P2 at a temperature of 120 \({}^{\circ}\)C was characterized by a maximum oxidation time of 78.80 min. Lipid oxidation at low and high temperatures can proceed via different reaction steps or pathways, depending on the reactivity of substances, such as antioxidants and metal ions at different temperatures. Lipid oxidation results in the loss of important nutrients in oils and fats, in addition to producing compounds such as free radicals that are harmful to health. In the food industry, through understanding the kinetics of lipid oxidation and the associated activation energy, it is possible to adjust the parameters and develop and control the production processes that preserve the nutritional quality of foods [46]. \begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{**Temperature of Oxidation**} & **Mathematical Equation of Regression** & **Pearson Index (\(r_{xy}\))** \\ \cline{2-3}  & **C18:1 Content (\(x\))** & \\ \hline \(100\)\({}^{\circ}\)C & \(y=-305.5+10.782x\) & \(0.535\) \\ \(110\)\({}^{\circ}\)C & \(y=-217.5+6.456x\) & \(0.648\) \\ \(120\)\({}^{\circ}\)C & \(y=-135.1+3.687x\) & \(0.775\) \\ \(130\)\({}^{\circ}\)C & \(y=-45.0+1.416x\) & \(0.831\) \\ \(140\)\({}^{\circ}\)C & \(y=-27.7+0.742x\) & \(0.814\) \\ \(100\)\({}^{\circ}\)C & \(y=727.6-12.980x\) & \(-0.550\) \\ \(110\)\({}^{\circ}\)C & \(y=399.2-7.703x\) & \(-0.661\) \\ \(120\)\({}^{\circ}\)C & \(y=216.2-4.364x\) & \(-0.784\) \\ \(130\)\({}^{\circ}\)C & \(y=89.6-1.666x\) & \(-0.836\) \\ \(140\)\({}^{\circ}\)C & \(y=43.0-0.877x\) & \(-0.822\) \\ \hline \hline \end{tabular}
\end{table}