Experimental parameters of central composition design (CCD).
| Factors | Symbol | Unit | Level | ||||
|---|---|---|---|---|---|---|---|
| −Alpha (−1.68) | Low (−1) | Medium (0) | High (+1) | +Alpha (+1.68) | |||
| Independent variables | |||||||
| Irradiation time | X 1 | Second | 3.2 | 10 | 20 | 30 | 36.8 |
| Microwave power | X 2 | W | 198a | 300 | 450 | 600 | 702a |
| LS ratio | X 3 | mL g−1 | 13.2 | 20 | 30 | 40 | 46.8 |
| Dependent variables | |||||||
| Madecassoside (MS) | Y 1 | mg g−1 dry weight | |||||
| Asiaticoside (AS) | Y 2 | mg g−1 dry weight | |||||
a
The extractions were performed with 180 W and 800 W microwave power instead, respectively, because the 198 W and 702 W power are not available in the microwave model used.