ISOLATION AND IDENTIFICATION OF AN ANTIOXIDANT PEPTIDE PREPARED FROM FERMENTED PEANUT MEAL USING BACILLUS SUBTILIS FERMENTATION

摘要

In order to recover and utilize peanut protein resource, peanut meal was fermented using Bacillus subtilis to prepare antioxidant peptides in this study. The antioxidant activities of the peanut peptides were evaluated via six in vitro tests, namely, 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) scavenging activity, inhibition of linoleic acid autoxidation, reducing power, and metal chelating capacity. The peanut peptides showed 63.28% of scavenging effect on 1,1-diphenyl-2-picrylhydrazyl radical, 70.67% of scavenging effect on 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) and 39.32% of superoxide anion radical scavenging activity at 1.0 mg/ml, and 62.69% of inhibition on linoleic acid autooxidation at 0.8 mg/ml. Besides, the peanut peptides exhibited 32.8% of reducing power and 60.44% of Fe~(2+)-chelating capacity at 2 mg/ml. Then the peanut peptides were desalted with macroporous resin; the fraction eluted with 75% ethanol showed the highest scavenging activity on 1,1-diphenyl-2-picrylhydrazyl radical. This fraction was subject to further purification using gel filtration chromatography and reverse phase-high performance liquid chromatography. At last, a peptide was gained, and it was identified to be Tyr-Pro with matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry. The results indicated that it is feasible to prepare natural antioxidants from peanut meal using B. subtilis fermentation.