Ultrasound-assisted extraction (UAE) of antioxidant phenolics from Corchorus olitorius leaves: a response surface optimization

Chemical and Biological Technologies in Agriculture

Table 4 Analysis of variance (ANOVA) of regression equation for optimization of TPC

Source	Sum of squares	df	Mean square	F-value	p-value	Significance
Model	156.67	14	11.19	39.78	< 0.0001	***
A-Ethanol conc. (%)	25.83	1	25.83	91.83	< 0.0001	***
B-Temperature (°C)	21.70	1	21.70	77.13	< 0.0001	***
C-Time (min)	10.61	1	10.61	37.73	< 0.0001	***
D-Liquid–solid ratio (mL/g)	0.9600	1	0.9600	3.41	0.0845	Ns
AB	10.24	1	10.24	36.40	< 0.0001	***
AC	1.78	1	1.78	6.34	0.0237	*
AD	0.0729	1	0.0729	0.2591	0.6181	Ns
BC	1.76	1	1.76	6.24	0.0246	*
BD	0.6241	1	0.6241	2.22	0.1571	Ns
CD	3.63	1	3.63	12.90	0.0027	**
A²	50.16	1	50.16	178.30	< 0.0001	***
B²	35.32	1	35.32	125.56	< 0.0001	***
C²	4.61	1	4.61	16.37	0.0011	**
D²	13.58	1	13.58	48.26	< 0.0001	***
Residual	4.22	15	0.2813
Lack of fit	3.49	10	0.3494	2.41	0.1720	Not significant
Pure error	0.7253	5	0.1451
Cor total	160.89	29
Std. dev	0.5304
Mean	11.27
C.V. %	4.70
Press	21.17
R²	0.9738
Adjusted R²	0.9493
Predicted R²	0.8684
Adeq precision	21.0264

***Highly significant (P < 0.001); **quite significant (0.001 < P < 0.01); *significant (0.01 < P < 0.05)