Table 1. Drying conditions which designed by central composite design
Condition No.
X
1
1)
X
2
2)
1
30
4
2
30
6
3
30
8
4
40
4
5
40
6
6
40
8
7
50
4
8
50
6
9
50
8
10
40
6
11
40
6
12
40
6
13
40
6
Drying temperature (°C).
Drying time (h).