Table 1 The central composite design for optimization of microwave-assisted extraction of blue honeysuckle
X
n
Response variables
Levels
-2
-1
0
1
2
X
1
Ethanol concentration (%)
0
25
50
75
100
X
2
Irradiation time (min)
1
4
7
10
13
X
3
Microwave power (W)
180
210
240
270
300