Table 2.
Independent variables, their levels for the Box–Behnken design, and the responses obtained.
| Run | X1 | X2 | X3 | TP | TPy | Gla | Iso |
|---|---|---|---|---|---|---|---|
| (%. w/w) | (°C) | (g) | (μg/mL) | (μg/g mL) | (μg/mL) | (μg/mL) | |
| 1 | 50 | 70 | 0.6 | 605.3 | 1008.8 | 9.12 | 3.20 |
| 2 | 10 | 45 | 0.6 | 529.6 | 882.7 | 4.37 | 2.48 |
| 3 | 50 | 70 | 1.0 | 753.9 | 753.9 | 14.11 | 5.20 |
| 4 | 50 | 45 | 0.8 | 606.3 | 757.8 | 5.29 | 3.31 |
| 5 | 10 | 70 | 0.8 | 790.6 | 988.3 | 6.56 | 3.11 |
| 6 | 50 | 45 | 0.8 | 779.1 | 973.9 | 6.56 | 2.86 |
| 7 | 50 | 45 | 0.8 | 676.8 | 846.0 | 6.09 | 2.79 |
| 8 | 90 | 20 | 0.8 | 279.5 | 349.3 | 12.9 | 2.00 |
| 9 | 10 | 45 | 1.0 | 748.7 | 748.7 | 6.96 | 4.27 |
| 10 | 10 | 20 | 0.8 | 633.6 | 792.0 | 3.99 | 3.47 |
| 11 | 50 | 45 | 0.8 | 582.2 | 727.7 | 4.40 | 2.07 |
| 12 | 90 | 70 | 0.8 | 518.7 | 648.3 | 17.30 | 5.76 |
| 13 | 90 | 45 | 0.6 | 302.1 | 503.4 | 10.14 | 2.47 |
| 14 | 50 | 45 | 0.8 | 620.8 | 776.0 | 6.39 | 3.29 |
| 15 | 50 | 20 | 1.0 | 638.3 | 638.3 | 7.63 | 3.79 |
| 16 | 90 | 45 | 1.0 | 346.6 | 346.6 | 16.18 | 4.26 |
| 17 | 50 | 20 | 0.6 | 447.4 | 745.7 | 5.48 | 2.02 |
Independent variables: X1 = glycerol content, X2 = temperature, X3 = weight of the plant material in 10 mL of solvent. TP, TPy, Gla, Iso: concentration of total phenols, TP/X3 ratio, glabridin and isoliquiritigenin, respectively.