## 3 Results and Discussion
### Optimization of Ultrasound Oil Extraction  
Based on the mathematical formulas, the optimal conditions of BB, CH, and RB oil extractions were determined. The optimization criteria were chosen in order to obtain maximum responses values. The variable conditions were set as in a range of 5-15 min extraction time and 20-100% ultrasound amplitude. One solution with appropriate desirability result was chosen for each oil extraction. The optimized conditions of UAE with actually applied conditions and predicted responses with real values measured are summarized in Table 4. The optimal conditions were adjusted to the capability of the ultrasound processor and applied in order to verify predicted values of experiment responses. It can be noted that the actual means of yield and OIT values were within maximum \(\pm\) 5% deviation from predicted results. It means that the predictions of the models were accurate and that applying RSM helps to forecast the results of the conducted experiment. The optimization of UAE of oil from BB, CH, or RB seeds was not discussed widely so far. [PERSON] et al. [32] studied the UAE of blackberry seed oil optimization. In the cited paper, ultrasound intensity, and extraction temperature and time were variables and extraction efficiency was a response. Researchers used n-hexane as a solvent in a 1/20 solid/liquid ratio. Based on the experiments, 13.77 W/cm\({}^{2}\), 45 \({}^{\circ}\)C, and 15 min were chosen as optimum ultrasound intensity, extraction temperature and time, respectively. Regarding the optimum time of extraction, in the following study, shorter extraction time was enough to achieve maximized response values for BB seed oil. [PERSON] et al. [33] optimized the ethanolic UAE of RB seed oil. The independent variables in their study were sonication time (10-50 min) and extraction temperature (30-70 \({}^{\circ}\)C), while one of the responses was extraction yield. The optimum conditions were described as 37 min extraction time in 54 \({}^{\circ}\)C temperature, which resulted in 22.78 \(\pm\) 0.27% extraction yield. Since the range of extraction time variable \begin{table}
\begin{tabular}{p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt}} \hline \hline
**Oil** & **Optimum Ultrasound Amplitude (\%)** & **Actual Ultrasound Amplitude (\%)** & **Optimum Amplitude (\%)** & **Predicted Extraction Time (min)** & **Predicted Yield (\%)** & **Predicted OIT (min)** & **Yield (\%)** & **OIT (min)** \\ \hline BB & 72.98 & 70 & 8.20 & 8.05 & 75.05 & 8.10 \(\pm\) 0.41 & 71.15 \(\pm\) 3.79 \\ CH & 59.18 & 60 & 10.11 & 6.10 & 49.38 & 6.02 \(\pm\) 0.97 & 48.78 \(\pm\) 0.69 \\ RB & 95.57 & 95 & 8.43 & 7.17 & 58.29 & 6.96 \(\pm\) 0.60 & 61.22 \(\pm\) 6.65 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Optimization results of ultrasound-assisted extraction of blackberry, chokeberry, and nspberry seed oils. \begin{table}
\begin{tabular}{p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt}} \hline \hline
**Oil** & **Model** & **R2** & **CV (\%)** & **Model _p-Value_** & **Model F-Value** & **Lack of Fit _p-Value_** \\ \hline BB & Quadratic & 0.9412 & 2.99 & 0.0142 & 12.81 & 0.3282 \\ CH & Quadratic & 0.9067 & 5.02 & 0.0346 & 7.78 & 0.1272 \\ RB & Linear & 0.5815 & 8.04 & 0.0474 & 4.86 & 0.1355 \\ \hline \hline \end{tabular}  
* CV—coefficient of variation.  
\end{table} 
Table 3: Model fitting of oil oxidation induction time. differed from the extraction time values applied in the following study, the comparison is not exactly possible. However, it could be concluded that [PERSON] et al. [33] reached very high extraction yield for RB seed oil, but it required longer sonication. Studies on optimization of UAE from other berry seeds were also carried out. [PERSON] et al. [34] described the UAE of sea buckthorn seed oil. The maximum extraction efficiency was reached while applying ultrasound intensity of 13.77 W/cm\({}^{2}\), temperature of 40 \({}^{\circ}\)C, and time of 10 min.