Table 1.

The experimental design and responses based on experimental trials.

Trial	Independent variables			Responses (dependent variables)a
	X 1	X2(°C)	X3 (h)	Y1 (%)	Y2 (%)
1	1.20	30.00	2.00	26.69	21.19
2	1.20	50.00	1.00	23.83	17.90
3	1.35	40.00	1.50	21.33	8.65
4	1.35	40.00	1.50	21.78	8.20
5	1.35	40.00	1.50	21.78	9.33
6	1.35	56.82	1.50	21.34	10.76
7	1.35	40.00	1.50	21.75	8.97
8	1.35	40.00	1.50	21.57	10.46
9	1.50	30.00	2.00	13.30	6.02
10	1.20	50.00	2.00	25.88	17.70
11	1.60	40.00	1.50	13.61	3.42
12	1.35	40.00	1.50	20.54	8.73
13	1.50	50.00	1.00	19.19	7.79
14	1.35	23.18	1.50	23.31	15.10
15	1.35	40.00	0.66	20.02	9.01
16	1.10	40.00	1.50	29.07	22.80
17	1.20	30.00	1.00	26.46	16.75
18	1.50	30.00	1.00	16.40	6.71
19	1.35	40.00	2.34	21.09	8.68
20	1.50	50.00	2.00	18.41	7.40

^aNitrogen insoluble in cold water (Y₁) or in hot water (Y₂).