Table 3. Comparison of Experimental and Predicted Values Using Box–Behnken Design for the Four Independent Variables on the Content of Polyphenol from Aqueous Acetone Extraction.

	extraction temperature (°C)	extraction time (min)	solvent composition (%)	liquid–solid ratio	experimental value (%)	predicted value (%)
test N	T	t	C	V	content	eq 1
1	50	90	20	20	9	9.61
2	50	90	100	20	10	10.23
3	50	90	60	20	13	10.11
4	45	120	40	25	13	12.57
5	50	150	60	20	13	13.57
6	50	90	60	20	10	10.23
7	55	120	40	25	9	8.61
8	55	120	80	15	12	14.19
9	50	90	60	10	7	10.11
10	55	60	40	25	8	9.61
11	45	120	40	15	8	10.23
12	45	120	80	15	7	8.52
13	60	90	60	20	9	7.90
14	45	60	80	25	14	14.19
15	50	30	60	20	10	8.52
16	55	60	80	25	13	11.11
17	55	60	40	15	12	10.23
18	45	120	80	25	11	11.73
19	55	60	80	15	9	8.61
20	50	90	60	30	7	8.73
21	40	90	60	20	13	12.69
22	50	90	60	20	15	12.69
23	45	60	40	15	12	10.23
24	45	60	40	25	7	7.02
25	45	60	80	15	11	10.23
26	55	120	40	15	7	7.02
27	55	120	80	25	11	11.11
28	50	90	60	20	6	6.90