Table 1 Central composite rotatable design (CCRD) showing independent variables, their levels and responses.
From: Supercritical fluid extraction of β-carotene from ripe bitter melon pericarp
Independent variables | Symbols | Coded variable levels | ||||
|---|---|---|---|---|---|---|
−2 | −1 | 0 | 1 | 2 | ||
Pressure (bar) | X1 | 150 | 225 | 300 | 375 | 450 |
Flow rate (mL/min) | X2 | 15 | 25 | 35 | 45 | 55 |
Temperature (°C) | X3 | 50 | 60 | 70 | 80 | 90 |
Time (min) | X4 | 45 | 90 | 135 | 180 | 225 |
