Table 4 Process variables and their levels used in CCD
Levels | ||||||
|---|---|---|---|---|---|---|
Independent variables | Coded symbols | -2 -1 0 1 2 | ||||
Temperature (°C) | A(X1) | 30 | 40 | 50 | 60 | 70 |
Molar ratio (D-isoascorbic: palmitic acid) | B(X2) | 1:1 | 1:2 | 1:3 | 1:4 | 1:5 |
Enzyme load (w/w) | C(X3) | 0.5 | 5 | 9.5 | 14 | 18.5 |
Ultrasonic power (W) | D(X4) | 60 | 90 | 120 | 150 | 180 |