Table 1.
The central composite design, coded and actual levels of three independent variables, actual and predicted values of total phenolic content.
| Run | X1 (Ethanol Concentration, %) | X2 (Solvent/Material Ratio, mL/g) | X3 (Temperature, °C) | Y (TPC Value, mg GAE/g DW) | |
|---|---|---|---|---|---|
| Actual | Predicted | ||||
| 1 | 20 (−1) | 40 (1) | 40 (−1) | 28.71 | 27.70 |
| 2 | 40 (1) | 40 (1) | 60 (1) | 30.32 | 30.32 |
| 3 | 30 (0) | 30 (0) | 50 (0) | 39.30 | 38.68 |
| 4 | 30 (0) | 46.82 (1.68) | 50 (0) | 30.33 | 30.50 |
| 5 | 40 (1) | 20 (−1) | 60 (1) | 28.11 | 29.60 |
| 6 | 20 (−1) | 20 (-1) | 60 (1) | 26.93 | 27.47 |
| 7 | 30 (0) | 30 (0) | 50 (0) | 39.42 | 38.68 |
| 8 | 40 (1) | 20 (−1) | 40 (−1) | 23.11 | 22.42 |
| 9 | 30 (0) | 30 (0) | 66.82 (1.68) | 32.63 | 30.96 |
| 10 | 30 (0) | 30 (0) | 50 (0) | 38.17 | 38.68 |
| 11 | 20 (−1) | 40 (1) | 60 (1) | 28.11 | 29.28 |
| 12 | 13.18 (−1.68) | 30 (0) | 50 (0) | 27.72 | 27.25 |
| 13 | 40 (1) | 40 (1) | 40 (−1) | 29.75 | 29.69 |
| 14 | 30 (0) | 30 (0) | 50 (0) | 38.65 | 38.68 |
| 15 | 30 (0) | 30 (0) | 33.18 (−1.68) | 22.61 | 23.60 |
| 16 | 20 (−1) | 20 (−1) | 40 (−1) | 18.87 | 19.35 |
| 17 | 30 (0) | 30 (0) | 50 (0) | 37.51 | 38.68 |
| 18 | 30 (0) | 13.18 (−1.68) | 50 (0) | 23.72 | 22.87 |
| 19 | 46.82 (1.68) | 30 (0) | 50 (0) | 30.91 | 30.70 |
| 20 | 30 (0) | 30 (0) | 50 (0) | 38.90 | 38.68 |