## 3 Results and Discussion
### The Antioxidant Activity
\begin{table}
\begin{tabular}{l c c c c c c} \hline \hline  & \
\begin{tabular}{c} **Sum of** \\ **Squares** \\ \end{tabular} & \multirow{2}{*}{**df**} &
\begin{tabular}{c} **Mean** \\ **Square** \\ \end{tabular} & \multirow{2}{*}{**F-Value**} & \multirow{2}{*}{**\(p\)-Value**} \\ \hline Model & 60.09 & 2 & 30.05 & 14.66 & 0.0006 & significant \\ A—Temperature & 27.17 & 1 & 27.17 & 13.25 & 0.0034 & \\ A\({}^{2}\) & 32.92 & 1 & 32.92 & 16.06 & 0.0017 & \\ \hline Residual & 24.60 & 12 & 2.05 & & & \\ \hline Lack of Fit & 22.57 & 10 & 2.26 & 2.23 & 0.3494 & not significant \\ \hline Pure Error & 2.03 & 2 & 1.01 & & & \\ \hline Cor Total & 84.70 & 14 & & & & \\ \hline Std. Dev. = 1.43; Mean = 16.17; C.V. \% = 8.86; R\({}^{2}\) = 0.7095; Adjusted R\({}^{2}\) = 0.6611; & & & & \\ Predicted R\({}^{2}\) = 0.5762; Adeq Precision = 7.5156. & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Analysis of variance for antioxidant activity measured using DPPH method. Figure 4: Antioxidant activity as a function of extraction temperature (**a**) Analyzed using DPPH method; (**b**) Analyzed using FRAP method. An F-value of 4.96 indicates that the model is significant. There is only a 4.43% chance that an F-value this large could occur due to noise. _p_-values less than 0.05 indicate significance of the model terms. A significant model term is A\({}^{2}\). The lack of fit F-value of 0.46 implies the lack of fit is not significant relative to the pure error. The predicted R\({}^{2}\) (0.0244) and adjusted R\({}^{2}\) (0.2203) are in reasonable agreement. The mathematical relation between the extraction temperature and antioxidant activity can be presented in the form of Equation (7) for the DPPH method and Equation (8) for the FRAP method. \[AC_{DPPH}=-0.003299~{}T^{2}+0.862411~{}T-38.31544 \tag{7}\]  
\[AC_{FRAP}=-3.49~{}T^{2}+23.33 \tag{8}\]  
where: AC--Trolox equivalent antioxidant activity [10\({}^{-6}\) MTE/1 g (DM)]; T--temperature [\({}^{\circ}\)C]. When we compare the antioxidant activity determined by both methods with the total polyphenols content obtained in previous evaluations, a similar trend of changes in the reference to the change in process temperature can be observed. Antioxidant activity assessed by use of the DPPH method increases with a temperature increase up to 131.6 \({}^{\circ}\)C, then decreases. The same trend was observed with polyphenols and flavonoid contents. A slight deviation with respect to this behavior was observed in relation to the FRAP method. The antioxidant activity determined by the FRAP method increases with an increase in temperature up to 134.7 \({}^{\circ}\)C, then decreases. The discrepancy in the temperature of occurrence of the maximum content of polyphenols and antioxidant activity measured by the FRAP method is 2.3%. Statistical data (e.g., coefficient of determination R\({}^{2}\)) for both analyses of antioxidant activity indicate a better adjustment of the regression curve in the case of the DPPH method (R\({}^{2}_{\text{DPPH}}\) = 0.7095 vs. R\({}^{2}_{\text{FRAP}}\) = 0.2760). Due to the uncertainty of the mathematical model build based on FRAP method, this model was used for qualitative assessment only.