Table 1 The central composite design condition of
Hordeum vulgare
L. extraction
Extraction condition
-2
-1
0
1
2
Ethanol concentration (%) (X
1
)
0
25
50
75
100
Microwave power (W) (X
2
)
60
120
180
240
300
Extraction time (min) (X
3
)
4
8
12
16
20