Enzymatic Hydrolysis Of Pea Protein And Antioxidative Activity Of The Hydrolysates

The pea proteins were hydrolyzed with diffent proteases. The enzymatic hydrolysisconditions of pea proteins were optimized by Response Surface Methodology (RSM) basedon single factor experiment. The antioxidant activity of pea protein hydrolysates weresystematically investigated in vitro. The molecular mass distribution of pea proteinhydrolysates were analyzed using HPLC System.Firstly, three proteases (Neutral protease, Alcalase, Flavorzyme) were choosed tohydrolyze pea proteins. The optimum enzymatic hydrolysis conditions of pea protein forFlavourzyme were: pH6.2, substrate concentration6.3%(W/V), hydrolysis time3.9h,enzyme/substrate4.0%(W/W), hydrolysis temperature48.8℃, under these conditions, thedegree of hydrolysis(DH) of pea protein was14.55%; The optimum conditions for Alcalasewere7.9,2.9%,3.0h,1.5%,54.5℃, respectively, and under these conditions, the DHwas13.42%; The optimum conditions for Neutral protease were6.5,5.2%,3.0h,3.0%,54.6℃,respectively, and under these conditions, the DH was7.82%.Secondly, Alcalase and Flavorzyme were used to hydrolyze pea proteins and the radicalscavenging activities of the hydrolysates were studied. The preparing conditions of thehydrolysates with high antioxidative activity were optimized by RSM. The optimumhydrolysis conditions for Flavorzyme were: temperature47.9℃, time3.1h, pH5.5,enzyme/substrate4.0%(W/W), substrate concentration6.0%(W/V), and under theseconditions, the DPPH· scavenging activity of the hydrolysates was60.10%; and for Alcalasethe hydrolysis conditions were:54.1℃,2.8h,6.5,3.0%,3.0%, respectively, and under theseconditions, the DPPH· scavenging activity of the hydrolysates was47.83%.Antioxidant activities in vitro of the pea protein hydrolysates prepared under optimumhydrolyzed conditions were also discussed. The relationship between DH and antioxidantactivity and the relationship between concentration of pea protein hydrolysates andantioxidant activities were estimated. The result indicated that the pea protein hydrolysatespossessed scavenging DPPH radical and showed strong reducing prower. It had the strongestantioxidative activity under some specific DH. The antioxidant activity of pea proteinhydrolysates was increased with the increasing of pea protein hydrolysates concentration atthe same DH.The antioxidant activity of pea protein hydrolysates were analyzed by Rancimat. TheInduction time was to reflect the antioxidant activity of the hydrolysates. The result showed that the protein hydrolysate prepared by flavorzyme had the best antioxidant ability.The molecule mass distribution of the pea protein hydrolysates mostly focused on800～1000Da using HPLC analysis. It showed that pea protein has been hydrolyzed as smallmolecule mass substance.