Extraction of functional natural products employing microwave-assisted aqueous two-phase system: application to anthocyanins extraction from mulberry fruits

Figures & data

Table 1. The design approach and experimental result of response surface methodology.

Run	Parameters				Y
	Factor 1(A)	Factor 2(B)	Factor 3(C)	Factor 4(D)
1	38	13	35	2	80.21 ± 0.85
2	40	14	30	3	82.35 ± 0.67
3	36	13	30	2	81.45 ± 1.28
4	38	14	30	2	84.82 ± 0.69
5	36	13	30	4	83.71 ± 0.92
6	40	13	30	2	81.99 ± 0.88
7	40	12	30	3	85.65 ± 0.76
8	36	14	30	3	82.85 ± 1.51
9	38	13	25	4	83.53 ± 0.76
10	40	13	25	3	82.51 ± 0.89
11	36	13	35	3	80.81 ± 1.25
12	38	12	35	3	86.52 ± 1.04
13	38	14	30	4	80.51 ± 0.59
14	38	13	30	3	88.64 ± 0.61
15	40	13	35	3	81.95 ± 0.82
16	38	12	25	3	86.32 ± 1.31
17	38	14	35	3	81.49 ± 0.91
18	38	14	25	3	85.85 ± 0.57
19	38	13	30	3	88.74 ± 0.64
20	38	13	30	3	88.95 ± 0.83
21	38	12	30	4	87.84 ± 1.32
22	38	12	30	2	83.68 ± 0.67
23	36	12	30	3	86.89 ± 0.68
24	38	13	35	4	83.24 ± 1.45
25	38	13	30	3	88.95 ± 0.94
26	38	13	30	3	89.2 ± 0.62
27	40	13	30	4	80.55 ± 1.08
28	38	13	25	2	84.18 ± 0.43
29	36	13	25	3	84.48 ± 1.28

A: ethanol concentration (%,w/w); B: ammonium sulfate concentration (%,w/w); C: microwave temperature (°C); D: microwave time (min); Y: recovery (%).

Figure 1. Aqueous two-phase (ATPE) diagram of ammonium ethanol sulfate.

Figure 2. The effects of six factors on the recovery (Y) and partition coeffificient (K) of mulberry anthocyanin. (A) Concentration of ethanol, (B) concentration of ammonium sulfate, (C) liquid-to-solid ratio, (D) microwave power, (E) microwave temperature, and (F) microwave time.

Table 2. ANOVA of the mulberry anthocyanin recovery test.

Source	Sum of squares	df	Mean square	F-value	P-value
Model	237.58	14	16.97	108.02	<0.0001	Significant
A	3.51	1	3.51	22.34	0.0023
B	30.18	1	30.18	192.11	<0.0001
C	14.63	1	14.63	93.13	<0.0001
D	1.73	1	1.73	10.98	0.0470
AB	0.14	1	0.14	0.87	0.3664
AC	5.09	1	5.09	32.37	0.0018
AD	9.61	1	9.61	61.17	0.0004
BC	5.20	1	5.20	33.09	<0.0001
BD	17.94	1	17.94	114.17	<0.0001
CD	3.39	1	3.39	21.55	0.0005
A^2	76.14	1	76.14	484.68	<0.0001
B2	7.37	1	7.37	46.93	<0.0001
C^2	49.09	1	49.09	312.51	<0.0001
D^2	74.37	1	74.37	631.26	<0.0001
Residual	2.20	14	0.16
Lack of Fit	1.94	10	0.19	2.97	0.1877	Not significant
Pure Error	0.26	4	0.0065
Cor Total	239.78	28
R^2 (99.01%)

Figure 3. Response surface analysis for the extraction variables on the recovery. (A) Recovery versus ethanol concentration and ammonium sulfate concentration, (B) recovery versus ethanol concentration and microwave temperature, (C) recovery versus ethanol concentration and microwave time, (D) recovery versus ammonium sulfate concentration and microwave temperature, (E) recovery versus ammonium sulfate concentration and microwave time, and (F) recovery versus microwave temperature and microwave time.

Figure 4. HPLC chromatograms of mulberry anthocyanins: cyanidin-3-O-glucoside, before MAATPE and after MAATPE.

Figure 5. FT-IR spectra of before and after MAATPE extract.

Figure 6. The scanning electron micrograph demonstrates the impact of various treatments on the mulberry’s surface microstructure: (A) mullberry powder; (B) MAE extraction; (C) ATPE extraction; and (D) MAATPE extraction.

Figure 7. Scavenging effects of mulberry extracts on DPPH radicals.

Figure 8. Scavenging effects of mulberry extracts on ABTS radicals.