Antioxidant properties of protein hydrolysate from Douchi by membrane ultrafiltration

Figures & data

Figure 1. Effect of A: extraction temperature, B: pH, C: ratio of water to raw material, D: extraction time, and E: E/S on the DPPH scavenging activity.

Table 1. Analysis of variance for the fitted quadratic polynomial model of the DPPH.IC₅₀ value.

Std. Dev.	Mean	C.V.	Press	R^2	R^2 Adj	R^2 Pred	Adeq Precision
13.80	262.18	5.26	15632.88	0.97	0.94	0.69	15.35

Figure 2. Response surface plots for the effects of E/S and extraction time (A,a); E/S and extraction temperature (B,b); and extraction temperature and extraction time (C,c) on the DPPH.IC50 value.

Table 2. Antioxidant activities of protein hydrolysate fractions separated by ultrafiltration.

Mw (kDa)	>50 kDa	50-10ka	10-5 kDa	＜5 kDa	Ascorbic acid
DPPH^.IC50 value (μg/mL)	198	154	535	2758	10

Table 3. Amino acid of protein hydrolysate fractions separated by ultrafiltration.

Amino acids	Crude protein	Mw:>50 kDa	Mw:50–10 kDa	Mw:10–5 kDa	Mw:＜5 kDa
Asp	6.18	5.80	6.83	5.34	4.12
Thr	2.06	2.11	2.38	1.62	1.24
Ser	2.77	2.79	3.24	2.73	1.83
Glu	10.19	9.72	11.47	7.50	6.27
Gly	2.17	2.14	2.48	1.93	1.39
Ala	2.41	2.59	2.99	1.81	1.36
Cys	0.62	0.63	0.68	1.38	0.99
Val	2.11	2.33	2.38	1.13	0.97
Met	0.75	0.75	0.82	0.83	0.55
Ile	1.95	2.06	2.10	1.05	0.94
Leu	3.65	3.80	4.12	2.61	1.98
Tyr	1.64	1.69	1.83	1.35	0.89
Phe	2.48	2.58	2.90	2.03	1.41
Lys	2.93	2.86	3.24	2.54	2.15
NH3	1.26	1.25	1.53	1.04	0.80
His	1.25	1.16	1.27	1.21	0.82
Arg	3.10	2.90	3.15	3.10	2.39
AAAS	16.37	15.52	18.30	12.84	10.39

Figure 3. Results of FTIR spectra.

Ashok, B.T.; Ali, R. The Aging Paradox: Free Radical Theory of Aging. Experimental Gerontology 1999, 34, 293–303.

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