## 3 Results and Discussion
### Optimization of the Extraction by RSM
\begin{table}
\begin{tabular}{c c c c c c} \hline
**Source** & **Sum of Squares** & **DF** & **Mean Square** & **F-Value** & \(p\)**-Value** \\ \hline _Block_ & \(2.19\times 10^{-2}\) & 1 & \(2.19\times 10^{-2}\) & – & – \\ _Model_ & \(2.47\) & 9 & \(0.27\) & \(59.88\) & \(0.00\) \\ \(X_{1}\) & \(0.81\) & 1 & \(0.81\) & \(176.41\) & \(0.00\) \\ \(X_{2}\) & \(0.32\) & 1 & \(0.32\) & \(70.75\) & \(0.00\) \\ \(X_{3}\) & \(0.31\) & 1 & \(0.31\) & \(67.93\) & \(0.00\) \\ \(X_{1}X_{2}\) & \(4.51\times 10^{-3}\) & 1 & \(4.51\times 10^{-3}\) & \(0.99\) & \(0.35\) \\ \(X_{1}X_{3}\) & \(1.51\times 10^{-3}\) & 1 & \(1.51\times 10^{-3}\) & \(0.33\) & \(0.58\) \\ \(X_{2}X_{3}\) & \(3.61\times 10^{-3}\) & 1 & \(3.61\times 10^{-3}\) & \(0.79\) & \(0.40\) \\ \(X_{1}\)\({}^{2}\) & \(0.19\) & 1 & \(0.19\) & \(42.05\) & \(0.00\) \\ \(X_{2}\)\({}^{2}\) & \(0.50\) & 1 & \(0.50\) & \(109.19\) & \(0.00\) \\ \(X_{3}\)\({}^{2}\) & \(0.51\) & 1 & \(0.51\) & \(111.27\) & \(0.00\) \\ _Residual_ & \(0.041\) & 9 & \(4.58\times 10^{-3}\) & – & – \\ Lack of fit & \(4.67\times 10^{-3}\) & 5 & \(9.34\times 10^{-4}\) & \(0.10\) & \(0.99\) \\ Pure error & \(0.037\) & 4 & \(9.14\times 10^{-3}\) & – & – \\ _Cor total_ & \(2.53\) & 19 & – & – & – \\ \hline \end{tabular}
\end{table} 
Table 2: ANOVA of response surface quadratic model for extraction yield of polysaccharides from _T. chinesis_ var. _mairei_. \begin{table}
\begin{tabular}{c c c c c} \hline
**Source** & **Sum of Squares** & **DF** & **Mean Square** & **F-Value** & \(p\)**-Value** \\ \hline _Block_ & \(0.00\) & \(1\) & \(0.00\) & – & – \\ _Model_ & \(3.71\times 10^{-2}\) & 9 & \(4.12\times 10^{-3}\) & \(168.37\) & \(0.00\) \\ \(X_{1}\) & \(7.32\times 10^{-6}\) & 1 & \(7.32\times 10^{-6}\) & \(0.30\) & \(0.60\) \\ \(X_{2}\) & \(1.52\times 10^{-2}\) & 1 & \(1.52\times 10^{-2}\) & \(619.48\) & \(0.00\) \\ \(X_{3}\) & \(1.74\times 10^{-3}\) & 1 & \(1.74\times 10^{-3}\) & \(71.05\) & \(0.00\) \\ \(X_{1}X_{2}\) & \(1.25\times 10^{-5}\) & 1 & \(1.25\times 10^{-5}\) & \(0.51\) & \(0.50\) \\ \(X_{1}X_{3}\) & \(1.25\times 10^{-5}\) & 1 & \(1.25\times 10^{-5}\) & \(0.51\) & \(0.50\) \\ \(X_{2}X_{3}\) & \(1.25\times 10^{-5}\) & 1 & \(1.25\times 10^{-5}\) & \(0.51\) & \(0.50\) \\ \(X_{1}\)\({}^{2}\) & \(8.84\times 10^{-3}\) & 1 & \(8.84\times 10^{-3}\) & \(361.15\) & \(0.00\) \\ \(X_{2}\)\({}^{2}\) & \(1.30\times 10^{-2}\) & 1 & \(1.30\times 10^{-2}\) & \(532.33\) & \(0.00\) \\ \(X_{3}\)\({}^{2}\) & \(1.13\times 10^{-3}\) & 1 & \(1.13\times 10^{-3}\) & \(46.23\) & \(0.00\) \\ _Residual_ & \(2.20\times 10^{-4}\) & 9 & \(2.45\times 10^{-5}\) & – & – \\ Lack of fit & \(1.45\times 10^{-4}\) & 5 & \(2.90\times 10^{-5}\) & \(1.55\) & \(0.35\) \\ Pure error & \(7.52\times 10^{-5}\) & 4 & \(1.88\times 10^{-5}\) & – & – \\ _Cor total_ & \(3.73\times 10^{-2}\) & 19 & – & – & – \\ \hline \end{tabular}
\end{table} 
Table 3: ANOVA of response surface quadratic model for the extraction yield of the essential oil _T. chinesis_ var. _mairei_. different values of the test variables and the interactions between the microwave power, extraction time and liquid/solid ratio (see Figure 4). Based on the above model, the maximum predicted yield of the polysaccharides was 6.43%, corresponding to an extraction time of 17.2 min, liquid/solid ratio of 22.0 (mL/g) and microwave power of 590 W. The maximum predicted yield of the essential oil was predicted to be 0.28%, corresponding to an extraction time of 17.7 min, liquid/solid ratio of 23.0 (mL/g), and microwave power of 504 W. Considering the recovery yields of the polysaccharides and essential oil, the optimal conditions for extracting these materials were identified as an extraction time of 17.5 min, liquid/solid ratio of 22.5 (mL/g), and microwave power of 547 W. Based on above the optimal conditions, a validation experiment was performed. The experimental results show that the yields of the polysaccharides and essential oil under the optimal extraction conditions were determined to be 6.39% \(\pm\) 0.12% and 0.27% \(\pm\) 0.03%, respectively.