Table 1 Independent variables, dependent variables and constraints for central composite design
Levels | |||||
Independent variables | Low (− 1) | Medium (0) | High (+ 1) | ||
X1 = chitosan (% w/v) | 2.75 | 3 | 3.25 | ||
X2 = NaTPP (% w/v) | 1.75 | 2 | 2.25 | ||
Constraints applied on dependent variables | |||||
Independent variables | Dependent variables | ||||
X1: chitosan (% w/v) | X2: NaTPP (% w/v) | Y1: particle size (um) | Y2: percentage yield (%) | Y3: entrapment efficiency (%) | |
Constraints | In range | In range | In range | Maximize | Maximize |
Importance | +++ | +++ | ++++ | ++++ | ++++ |