Optimization of Vacuum Microwave-Mediated Extraction of Syringoside and Oleuropein from Twigs of Syringa oblata

Table 1

Experimental data and the observed response value with different combinations of microwave irradiation time (X₁), liquid-solid ratio (X₂), and microwave irradiation power (X₃) used in the Box–Behnken design.

Run number	Experimental design			Dependent variables
	X1: microwave irradiation time (min)	X2: liquid-solid ratio (mL/g)	X3: microwave irradiation power (W)	Yield of syringoside (mg/g)		Yield of oleuropein (mg/g)
				Predicted yield	Actual yield	Predicted yield	Actual yield
1	4	10	385	3.82	3.82	3.39	3.44
2	8	10	385	4.86	4.94	3.43	3.40
3	4	20	385	3.81	3.73	3.35	3.37
4	8	20	385	5.27	5.27	3.72	3.67
5	4	15	230	3.65	3.63	3.02	2.92
6	8	15	230	4.02	3.92	2.22	2.20
7	4	15	540	3.73	3.83	2.89	2.91
8	8	15	540	5.86	5.88	4.10	4.20
9	6	10	230	4.13	4.14	2.77	2.82
10	6	20	230	4.40	4.51	3.04	3.11
11	6	10	540	5.16	5.05	3.78	3.70
12	6	20	540	5.29	5.28	3.77	3.73
13	6	15	385	5.57	5.71	3.78	3.89
14	6	15	385	5.57	5.57	3.78	3.78
15	6	15	385	5.57	5.52	3.78	3.76
16	6	15	385	5.57	5.39	3.78	3.65
17	6	15	385	5.57	5.68	3.78	3.81