Table 2.

Experimental plan and corresponding α-amylase activity.

Run order	Glucose (g·L−1)		Yeast extract powder (g·L−1)		Proline (g·L−1)		α-Amylase activity (×103 U·mL−1)
	Code A	A	Code B	B	Code C	C	Predicted	Actual
1	1	24.93	−1	10.07	1	12.16	10.03	10.18 ± 0.25
2	−1	10.07	1	24.93	−1	3.84	6.50	7.00 ± 0.21
3	0	17.50	0	17.50	0	8.00	16.89	17.00 ± 0.45
4	0	17.50	0	17.50	−1.68	1.00	7.67	7.15 ± 0.22
5	0	17.50	0	17.50	0	8.00	16.89	16.90 ± 0.38
6	1	24.93	−1	10.07	−1	3.84	8.85	8.00 ± 0.21
7	0	17.50	0	17.50	0	8.00	16.89	17.00 ± 0.45
8	1	24.93	1	24.93	−1	3.84	8.85	7.90 ± 0.22
9	1	24.93	1	24.93	1	12.16	6.66	6.35 ± 0.21
10	−1	10.07	−1	10.07	1	12.16	10.20	11.50 ± 0.31
11	0	17.50	0	17.50	0	8.00	16.89	16.70 ± 0.41
12	0	17.50	−1.68	5.00	0	8.00	9.82	8.72 ± 0.21
13	0	17.50	0	17.50	0	8.00	16.89	16.92 ± 0.43
14	0	17.50	0	17.50	1.68	15.00	9.54	9.20 ± 0.25
15	0	17.50	1.68	30.00	0	8.00	7.69	8.30 ± 0.23
16	−1	10.07	1	24.93	1	12.16	6.48	6.50 ± 0.21
17	−1	10.07	−1	10.07	−1	3.84	5.35	6.00 ± 0.22
18	1.68	30.00	0	17.50	0	8.00	8.69	9.50 ± 0.32
19	−1.68	5.00	0	17.50	0	8.00	6.59	5.30 ± 0.17