Table 1 Experimental domain and independent variables for optimization
| Â | Factors (Symbol, Units) | Lower level | Middle level | Upper level |
|---|---|---|---|---|
Drying | Temperature (X1, °C) | 40 | 55 | 70 |
Time (X2, min) | 180 | 195 | 210 | |
Roasting | Temperature (X1, °C) | 140 | 160 | 180 |
Time (X2, min) | 5 | 15 | 25 | |
Steam blanching | Temperature (X1, °C) | 80 | 90 | 100 |
Time (X2, min) | 5 | 10 | 15 | |
Fermentation/Oxidation | Temperature (X1, °C) | 25 | 35 | 45 |
Time (X2, min) | 15 | 52.5 | 90 |