Table 2.

Analysis of variance for central composite design and tests of the regression coefficients and intercepts of coded equations for curdione, furanodienone, curcumol and germacrone

Source		Mean squares	F	p value	Coefficient estimate
Curdione	Model	0.075	12.99	0.0014
	Intercept				1.790
	X 1	0.360	61.88	0.0001	0.160
	X 2	0.120	20.88	0.0026	0.094
	X 3	0.042	7.29	0.0307	0.056
	X 1 X 2	0.029	5.04	0.0596	−0.060
	X 1 X 3	1.326 × 10−3	0.23	0.6466	−0.013
	X 2 X 3	8.001 × 10−3	1.38	0.2779	0.032
	X 21	4.588 × 10−3	0.79	0.4027	−0.020
	X 22	0.110	19.80	0.0030	−0.100
	X 23	3.531 × 10−3	0.61	0.4601	−0.018
	Lack of Fit	6.474 × 10−3	1.60	0.4281
	R 2 = 0.9435, Q 2 = 0.8677, Adeq Precision = 12.121
Furanodienone	Model	0.098	27.14	0.0001
	Intercept				1.370
	X 1	0.330	90.16	<0.0001	0.150
	X 2	0.190	51.54	0.0002	0.120
	X 3	0.110	29.00	0.0010	0.088
	X 1 X 2	9.730 × 10−3	2.69	0.1452	−0.035
	X 1 X 3	1.966 × 10−3	0.54	0.4852	−0.013
	X 2 X 3	1.566 × 10−4	0.04	0.8412	4.425 × 10−3
	X 21	0.025	7.01	0.0331	−0.047
	X 22	0.250	70.00	<0.0001	−0.150
	X 23	0.015	4.14	0.0813	−0.036
	Lack of Fit	3.853 × 10−3	1.27	0.4963
	R 2 = 0.9721, Q 2 = 0.9117, Adeq Precision = 16.176
Curcumol	Model	2.694 × 10−3	15.43	0.0008
	Intercept				0.210
	X 1	8.931 × 10−3	51.15	0.0002	0.026
	X 2	4.953 × 10−3	28.37	0.0011	0.019
	X 3	2.519 × 10−3	14.43	0.0067	0.014
	X 1 X 2	1.739 × 10−4	1.00	0.3515	−4.663 × 10−3
	X 1 X 3	9.453 × 10−5	0.54	0.4858	3.437 × 10−3
	X 2 X 3	9.045 × 10−5	0.52	0.4950	3.362 × 10−3
	X 21	3.674 × 10−7	2.10 × 10−3	0.9647	−1.805 × 10−4
	X 22	6.848 × 10−3	39.22	0.0004	−0.025
	X 23	2.553 × 10−4	1.46	0.2658	−4.759 × 10−3
	Lack of Fit	2.209 × 10−4	3.76	0.2232
	R 2 = 0.9520, Q 2 = 0.8957, Adeq Precision = 14.233
Germacrone	Model	7.756 × 10−3	16.36	0.0007
	Intercept				0.350
	X 1	0.023	49.39	0.0002	0.041
	X 2	0.010	21.15	0.0025	0.027
	X 3	9.435 × 10−3	19.90	0.0029	0.026
	X 1 X 2	8.694 × 10−4	1.83	0.2178	−0.010
	X 1 X 3	9.940 × 10−5	0.21	0.6609	3.525 × 10−3
	X 2 X 3	1.682 × 10−5	0.04	0.8559	1.450 × 10−3
	X 21	7.945 × 10−4	1.68	0.2365	−8.395 × 10−3
	X 22	0.025	52.89	0.0002	−0.047
	X 23	4.873 × 10−4	1.03	0.3444	−6.574 × 10−3
	Lack of Fit	6.264 × 10−4	6.72	0.1346
	R 2 = 0.9546, Q 2 = 0.9076, Adeq Precision = 13.465

X ₁ Liquid to solid ratio (mL g⁻¹); X ₂ Ethanol concentration (%); X ₃ Ultrasonic time (min)