Table 1 The investigated variables with their codes and levels for the full factorial design
Variables | Code | Low level (-1) | High level (+1) |
|---|---|---|---|
pH | A | 5 | 8 |
Temperature (°C) | B | 50 | 75 |
Incubation period (h) | C | 24 | 96 |
Aeration | D | Aerobic conditions | Anaerobic conditions |