| Variables | Extreme Negative (−1) | Extreme Positive (+1) |
| Molar ratio—oil:alcohol [R] | 1:6 | 1:10 |
| Temperature [T] (˚C) | 40 | 60 |
| Enzyme percentage [E] (%p/p) | 3 | 7 |
| Alcohol type | Ethanol | Methanol |