Mathematical Modelling and Optimisation of Low-Temperature Drying on Quality Aspects of Rough Rice

Table 2

Central composite design and experimental process.

Run		Coded form			HRY		Hardness		Lightness		Cooking time
		X1	X2	X3	Observed	Predicted	Observed	Predicted	Observed	Predicted	Observed	Predicted
1		−1	−1	−1	72.54	72.62	23.1	22.93	69.86	68.91	21.4	21.07
2		1	−1	−1	70.55	71.08	48.62	48.59	74.13	73.61	31.5	31.66
3		−1	1	−1	75.23	73.93	35.12	38.28	71.54	71.40	26.7	27.58
4		1	1	−1	66.81	66.52	59.36	63.35	78.33	78.66	33.2	34.86
5		−1	−1	1	71.87	71.58	26.65	25.32	70.17	69.30	23.1	22.51
6		1	−1	1	69.73	70.46	51.62	51.12	74.75	74.34	33.2	33.39
7		−1	1	1	73.86	72.76	41.76	44.46	72.27	72.25	27.5	28.41
8		1	1	1	66.42	65.77	66.83	69.67	79.43	79.84	34.6	36.0
9		−1.682	0	0	70.76	72.03	27.76	26.45	68.24	69.15	22.6	22.6
10		1.682	0	0	65.32	64.86	71.69	69.23	79.64	79.49	39.4	37.88
11		0	−1.68	0	72.93	72.03	29.71	32.2	69.44	70.81	23.7	24.56
12		0	1.682	0	67.47	69.18	66.98	60.72	78.14	77.53	34.6	32.23
13		0	0	−1.68	73.47	73.77	40.76	37.91	70.44	70.94	29.5	28.61
14		0	0	1.682	71.76	72.27	46.16	45.24	72.01	72.27	31.4	30.78
15		0	0	0	72.12	72.35	42.76	42.43	70.11	70.54	30.2	29.58
16		0	0	0	72.97	72.35	43.12	42.43	70.72	70.54	28.6	29.58
17		0	0	0	71.34	72.35	38.97	42.43	70.02	70.54	30.5	29.58
18		0	0	0	72.11	72.35	44.23	42.43	70.12	70.54	29.6	29.58
19		0	0	0	73.11	72.35	40.38	42.43	70.96	70.54	29.8	29.58
20		0	0	0	72.56	72.35	44.45	42.43	71.42	70.54	28.5	29.58

X₁ = temperature; X₂ = time; X₃ = velocity.