| Variable | Symbol | Code-variable level | ||
| −1 | 0 | 1 | ||
| Temperature (˚C) | X1 | 30 | 37.5 | 45 |
| Alcohol (v/v) | X2 | 5 | 12.5 | 20 |
| Acid acetic (w/v) | X3 | 0 | 1 | 2 |