The antioxidant activity varied statistically (P < 0.001) from 29.13 (assay 4) to 51.78% (assay 13). Multiple regression analysis showed that the model was significant (P < 0.001) and adequately adjusted the experimental data with Plack of fit = 0.31, explaining 72% of the variance in the data. The temperature (x1) in the linear model showed a significant and positive effect on increasing the antioxidant activity. The temperature (x12) and the solvent ratio (x22) showed a significant effect and tended to decrease the antioxidant activity.