Process Optimization of Ultrasonic-Assisted Extraction of Arabinogalactan from Dihydroquercetin Extracted Residues by Response Surface Methodology and Evaluation of Its Antioxidant Activity

Table 2

Test of significance for regression coefficient and the credibility analysis^a.

Source	Sum of squares	Regression coefficient		Degree of freedom	Mean square	𝐹-value	𝑃-value
Model^b	6.57	9.75		9	0.73	5.20	0.0204
𝑋1	1.83	0.48		1	1.83	13.07	0.0086
𝑋2	0.01	−0.04		1	0.01	0.08	0.7852
𝑋3	0.09	−0.10		1	0.09	0.61	0.4591
𝑋1𝑋2	1.17	−0.54		1	1.17	8.31	0.0235
𝑋1𝑋3	0.38	−0.31		1	0.38	2.70	0.1446
𝑋2𝑋3	2.19	0.74		1	2.19	15.61	0.0055
𝑋12	0.59	0.37		1	0.59	4.18	0.0801
𝑋22	0.36	0.29		1	0.36	2.60	0.1510
𝑋32	0.00	0.00		1	0.00	0.00	0.9652
Residual	0.98			7	0.14
Lack of fit	0.58			3	0.19	1.89	0.2730
Pure error	0.41			4	0.10
Cor total	7.55			16
Std. dev.	Mean	C.V. %	Press	R ^2	Adjust 𝑅^2	Predicted 𝑅^2	Adequacy precision
0.37	9.79	3.83	9.84	0.8700	0.7028	−0.3029	8.2281

aThe results were obtained with the Design Expert 8.0 software.
^b𝑋₁ is liquid-solid ratio (mL/g). 𝑋₂ is ultrasound irradiation time (min). 𝑋₃ is extraction temperature (°C).