Comparative Studies of Combined Influence of Variables on the Esterification Degree of Pectin Extracted by Sulfuric Acid and Citric Acid

Table 3

Results of analysis of variance (ANOVA) for DEs.

Source	Sum of squares	DF	Mean square	F-value	P-value
X 1	12.50	1	12.50	36.56	0.0005
X 2	68.33	1	68.33	199.87	<0.0001
X 3	214.66	1	214.66	627.91	<0.0001
X 1 X 2	0.77	1	0.77	2.27	0.1760
X 1 X 3	0.71	1	0.71	2.06	0.1940
X 2 X 3	0.67	1	0.67	1.97	0.2035
X 1^2	2.11	1	2.11	6.17	0.0420
X 2^2	10.54	1	10.54	30.84	0.0009
X 3^2	0.57	1	0.57	1.66	0.2381
Model	311.86	9	34.65	101.36	<0.0001
Residual	2.39	7	0.34	—	—
Lack of fit	2.39	3	0.80	—	—
Pure Error	0.000	4	0.000	—	—
Cor Total	314.25	16	—	—	—