## 3 Results and Discussion
### Oxidative Stability of Sea Buckthorn and Rose Hip Oils
Figures 4 and 5 show a graphical relationship between the logarithm of the induction time and the reciprocal of the measurement temperatures of sea buckthorn and rosehip oils, respectively. Table 3 presents the activation energy and adjustable coefficients for the oxidation reaction of sea buckthorn and rosehip oils. \begin{table}
\begin{tabular}{c c c c c} \hline
**Parameter** & **Rosehip Oil R1** & **Rosehip Oil R2** & **Sea Buckthorn Oil B1** & **Sea Buckthorn Oil B2** \\ \hline AV (mg KOH/g of fat) & 0.26 \(\pm\) 0.09 \({}^{\text{a}}\) & 2.91 \(\pm\) 0.84 \({}^{\text{c}}\) & 1.00 \(\pm\) 0.32 \({}^{\text{b}}\) & 1.50 \(\pm\) 0.29 \({}^{\text{b}}\) \\ \hline PV (meq O\({}_{2}\)/kg of fat) & 2.04 \(\pm\) 0.32 \({}^{\text{a}}\) & 3.21 \(\pm\) 0.43 \({}^{\text{b}}\) & 5.21 \(\pm\) 0.54 \({}^{\text{c}}\) & 4.01 \(\pm\) 0.35 \({}^{\text{b}}\) \\ \hline Induction time at 100 \({}^{\text{c}}\)C (min) & 203.36 \(\pm\) 13.98 \({}^{\text{c}}\) & 137.61 \(\pm\) 6.10 \({}^{\text{b}}\) & 80.36 \(\pm\) 0.73 \({}^{\text{a}}\) & 149.12 \(\pm\) 1.95 \({}^{\text{b}}\) \\ \hline Induction time at 110 \({}^{\text{c}}\)C (min) & 88.42 \(\pm\) 0.91 \({}^{\text{c}}\) & 56.35 \(\pm\) 0.23 \({}^{\text{b}}\) & 36.52 \(\pm\) 1.86 \({}^{\text{a}}\) & 71.20 \(\pm\) 1.67 \({}^{\text{d}}\) \\ \hline Induction time at 120 \({}^{\text{c}}\)C (min) & 40.58 \(\pm\) 2.50 \({}^{\text{c}}\) & 24.45 \(\pm\) 1.77 \({}^{\text{b}}\) & 17.81 \(\pm\) 1.44 \({}^{\text{a}}\) & 36.56 \(\pm\) 3.51 \({}^{\text{c}}\) \\ \hline Induction time at 130 \({}^{\text{c}}\)C (min) & 19.32 \(\pm\) 1.43 \({}^{\text{b}}\) & 10.85 \(\pm\) 0.30 \({}^{\text{a}}\) & 8.65 \(\pm\) 1.48 \({}^{\text{a}}\) & 17.57 \(\pm\) 1.41 \({}^{\text{b}}\) \\ \hline Induction time at 140 \({}^{\text{c}}\)C (min) & 8.96 \(\pm\) 0.77 \({}^{\text{b}}\) & 4.07 \(\pm\) 0.27 \({}^{\text{a}}\) & 3.60 \(\pm\) 0.46 \({}^{\text{a}}\) & 8.40 \(\pm\) 0.87 \({}^{\text{b}}\) \\ \hline \end{tabular} Data denoted by the same letter are not statistically different (\(\alpha\) = 0.05).  
\end{table} 
Table 2: Induction time at temperatures 100, 110, 120, 130, and 140 \({}^{\text{c}}\)C; acid value and peroxide value of sea buckthorn and rosehip oils. Data from this equation describing the linear relationship were the starting point for calculating the activation energy of the analyzed rosehip and sea buckthorn oils. The activation energy of an oxidation reaction is defined as the smallest amount of energy  
Figure 4: Log induction time versus reciprocal oxidation temperature of sea buckthorn oils. Figure 5: Log induction time versus reciprocal oxidation temperature of rosehip oils. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Parameters** & **Rosehip Oil R1** & **Rosehip Oil R2** & \
\begin{tabular}{c} **Sea Buckthorn** \\ **Oil B1** \\ \end{tabular} &
\begin{tabular}{c} **Sea Buckthorn** \\ **Oil B2** \\ \end{tabular} \\ \hline a & 5.2015 \(\pm\) 0.06 b  & 5.8124 \(\pm\) 0.16 b  & 5.1194 \(\pm\) 0.24 b  & 4.786 \(\pm\) 0.20 a  \\ b & 11.627 \(\pm\) 0.19 b  & 13.419 \(\pm\) 0.41 c  & 11.796 \(\pm\) 0.65 b  & 10.638 \(\pm\) 0.53 a  \\ R2 & 0.999 & 0.997 & 0.996 & 0.998 \\ Ea (kJ/mol) & 94.74 \(\pm\) 1.17 b  & 105.85 \(\pm\) 2.93 c  & 93.93 \(\pm\) 4.41 b  & 87.23 \(\pm\) 3.58 a  \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Adjustable coefficients and activation energy of oxidation reaction of sea buckthorn and rosehip oils. necessary to initiate oxidation processes in a molecule. The activation energy was at the level of 87.23-93.93 kJ/mol in sea buckthorn oil and 94.74-105.85 kJ/mol in rosehip oil. Although rosehip oil R1 and sea buckthorn oil B2 were characterized by longer induction times, lower values of activation energy were determined for these oils compared to oils R2 and B1, for which lower values of induction times and higher values of activation energy were recorded. A similar tendency was observed by [PERSON] et al. [5] in a study on rosehip oil, stating that fatty acid composition strongly affected the activation energy of oils.