| Levels | |||
Factors | 1 | 2 | 3 | 4 |
Soda Concentration (N) | 0.2 | 0.4 | 0.6 | 0.8 |
Temperature (˚C) | 60 | 80 | 100 | 120 |
Time (min) | 30 | 60 | 90 | 120 |