Table 1.
Experimental design of RSM studies using two independent variables with three centre points, showing observed and predicted values of vanillin molar yield and specific productivity.
| Vanillin Molar yield (%) | Specific Productivity (μmol vanillin/g biomass × min) | |||||
| Experiment | Biomass (g/L) | Ferulic acid (mM) | Observed | Predicted | Observed | Predicted |
| 1 | 1.0 (-1) | 0.5 (-1) | 65.4 | 66.4 | 4.27 | 4.01 |
| 2 | 4.5 (0) | 0.5 (-1) | 75.3 | 74.9 | 1.61 | 1.90 |
| 3 | 8.0 (1) | 0.5 (-1) | 68.0 | 66.9 | 0.88 | 0.67 |
| 4 | 1.0 (-1) | 2.8 (0) | 54.4 | 52.6 | 6.92 | 7.33 |
| 5 | 4.5 (0) | 2.8 (0) | 68.4 | 68.3 | 5.94 | 5.80 |
| 6 | 8.0 (1) | 2.8 (0) | 65.0 | 67.4 | 4.57 | 4.79 |
| 7 | 1.0 (-1) | 5.0 (1) | 33.1 | 33.7 | 5.81 | 5.73 |
| 8 | 4.5 (0) | 5.0 (1) | 55.7 | 56.5 | 4.58 | 4.60 |
| 9 | 8.0 (1) | 5.0 (1) | 63.9 | 62.6 | 4.10 | 4.08 |
| 10 | 4.5 (0) | 2.8 (0) | 68.4 | 68.3 | 5.94 | 5.80 |
| 11 | 4.5 (0) | 2.8 (0) | 68.5 | 68.3 | 5.94 | 5.80 |
| 12 | 4.5 (0) | 2.8 (0) | 68.2 | 68.3 | 5.94 | 5.80 |
(-1), (0) and (1) are coded levels