## 3 Results and Discussion
### Optimization of the Extraction Conditions  
In order to select optimal extraction conditions yielding extracts with the highest possible content of bioactive compounds and the highest antioxidant activity, and based on the results from the first stage of research, a new plan of experiments was created on the basis of the central compositional plan 2\({}^{2}\). In this plan, SMR and solvent concentration were left as extraction process variables, extending their range compared to the first step plan. At this stage, a broader analysis of the extracts was also carried out, including the antioxidant activity determined by the ABTS and FRAP methods, the TPC, the so-called browning factor and caffeine and chlorogenic acid (3-CQA) content. The results of the analyses of ethanol extracts prepared in the second stage of the research are presented in Table 4.  
Recently, non-conventional methods such as ultrasound/microwave-assisted extraction or subcritical water extraction are commonly applied as alternative extraction techniques to traditional extraction processes. These techniques are recognized as more environmentally friendly with better overall yield. Conventional extraction methods are still considered as the reference methods to modern methodology [67]. [PERSON] et al. [68] compared conventional solvent extraction (CSE) with ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE). The authors demonstrated that, in the case of TPC, UAE and CSE gave similar results, while MAE TPC yield was significantly lower. CSE TPC ranged between 8.05 and 10.58 mg GAE/g d.m. CS, which is in agreement with the results of this study. In recent years, one of the most efficient methods of TPC \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Type of Sample**} & **ABTS** & **FRAP** & **TPC** & **BI** & **Caffeine** & **3\(-\)CQA** \\  & **[umol Torlo\(\times\)]** & **[umol Fe(II)/g** & **[umol GAE/** & **[Abs420]** & **[mg/g CS d.m.]** & **[mg/g CS d.m.]** \\  & **g CS d.m.]** & **CS d.m.]** & **g CS d.m.]** & **[**]** & **[**]** \\ \hline
1 & 54.63 \(\pm\) 0.54 & 90.50 \(\pm\) 2.88 & 38.73 \(\pm\) 0.56 & 0.401 \(\pm\) 0.006 & 5.16 \(\pm\) 0.26 & 0.324 \(\pm\) 0.009 \\
2 & 64.57 \(\pm\) 1.29 & 124.24 \(\pm\) 1.05 & 49.29 \(\pm\) 0.57 & 0.364 \(\pm\) 0.003 & 6.09 \(\pm\) 0.02 & 0.428 \(\pm\) 0.002 \\
3 & 72.98 \(\pm\) 1.24 & 139.94 \(\pm\) 2.48 & 43.88 \(\pm\) 1.61 & 0.201 \(\pm\) 0.006 & 6.60 \(\pm\) 0.01 & 0.356 \(\pm\) 0.001 \\
4 & 90.51 \(\pm\) 1.10 & 183.15 \(\pm\) 0.74 & 54.37 \(\pm\) 1.68 & 0.187 \(\pm\) 0.004 & 6.75 \(\pm\) 0.06 & 0.415 \(\pm\) 0.003 \\
5 & 62.22 \(\pm\) 0.96 & 131.25 \(\pm\) 1.37 & 43.46 \(\pm\) 0.76 & 0.260 \(\pm\) 0.007 & 6.34 \(\pm\) 0.06 & 0.401 \(\pm\) 0.003 \\
6 & 73.68 \(\pm\) 0.86 & 138.29 \(\pm\) 1.37 & 41.07 \(\pm\) 0.64 & 0.202 \(\pm\) 0.006 & 6.77 \(\pm\) 0.27 & 0.383 \(\pm\) 0.001 \\
7 & 37.22 \(\pm\) 0.34 & 65.77 \(\pm\) 0.44 & 24.25 \(\pm\) 0.33 & 0.373 \(\pm\) 0.006 & 3.23 \(\pm\) 0.06 & 0.292 \(\pm\) 0.005 \\
8 & 82.42 \(\pm\) 2.49 & 161.87 \(\pm\) 2.30 & 52.67 \(\pm\) 1.72 & 0.233 \(\pm\) 0.005 & 6.67 \(\pm\) 0.10 & 0.200 \(\pm\) 0.002 \\
9 & 101.67 \(\pm\) 0.94 & 130.69 \(\pm\) 0.71 & 50.31 \(\pm\) 1.11 & 0.297 \(\pm\) 0.005 & 5.94 \(\pm\) 0.06 & 0.447 \(\pm\) 0.004 \\
10 & 102.63 \(\pm\) 0.92 & 132.55 \(\pm\) 0.71 & 51.04 \(\pm\) 1.31 & 0.297 \(\pm\) 0.013 & 6.15 \(\pm\) 0.06 & 0.430 \(\pm\) 0.005 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: The results of the applied RSM responses in the second stage of extraction optimization experimental design—ABTS, FRAP, TPC, BI assays values and caffeine and chlorogenic acids contents for tested variants of ethanolic CS extracts. Figure 3: Pareto charts of ethanol concentration, SMR, extraction time, and type of used extraction apparatus on the antioxidant activity measured by the ABTS assay (**a**) and TPC determination (**b**). extraction is subcritical water extraction. With the use of this method, [PERSON] et al.