Study On Antioxidant Activity Of Low-molecular Weight Peptides From Wheat Bran By Enzymatic Membrane Reactor

Wheat bran is a major by-product during flour processing, containing12to18％protein. It is ahigh-quality natural plant protein resource. China’s overall level of utilization of wheat bran is still inthe primary stage of development until now. The economic value is not high and it caused a seriouswaste of resources.Wheat is the major grain crop in our country. The yield of wheat bran, as by-product in theprocess of wheat, is very huge. However, at present, the effective utilization rate of wheat bran islow, which is not fully developed and effective utilized. Wheat bran contains abundant plantprotein. A variety of ways are now studied to utilized wheat bran as raw material to prepare wheatbran peptide, but the study of enzyme membrane reaction to produce low-molecular WeightPeptide from wheat bran has not been reported. This paper use enzyme membrane reaction toprepare low-molecular Weight Peptide successfully and the preparation dynamics and antioxidantactivity were also studied to provide theoretical foundation and experimental basis for furtherdevelop of wheat bran.In this paper, the wheat bran protein was prepared by alkali method and then hydrolysedintermittently. The screening of Proteolytic Enzymes was performed and the conditions andkinetics of enzymolysis were also studied. On this basis, low-molecular Weight Peptides wereprepared by using enzyme membrane reaction to hydrolyze wheat bran protein continuously.Furthermore, Cytology antioxidant activity （CAA） and in vitro chemical oxidation resistancemethod （ORAC） were used to study low-molecular Weight Peptides. The main results are asfollows:(1) The hydrolysis degree in unit time was used as an indicator to screen the optimal protease.The comparison of the alkaline, trypsin, papain and complex protease indicates that the alkalineprotease has the maximum hydrolysis degree, which is16.52％in120min. (2) The single factor method was used to optimize the hydrolysis conditions. The optimalhydrolysis process are as follows: the ratio of enzyme and substrate is6％, the reactiontemperature50℃, pH9.0.(3) The study of the enzymolysis kinetics indicates the enzyme and substrate inhibitioncoexists simultaneously in the process of enzymolysis. The main kinetic parameters are asfollows: k=43.39g/kg, Vmax=tendency for1.12/kg/min, Ks=58.82g/kg, k2=3.73. Theenzymolysis kinetic equation is V3.73[E0]0143.39[S0][S0]58.82(4) Comparing the different liquid through ultrafiltration membrane, the results show that theoptimal ultrafiltration membrane is1kD. In the liquid through1kd ultrafiltration membrane, sm-all molecular peptides（2～4peptide）accounts for the largest percentage of peak area, its valueis77.35％, and the largest yield, its value is20.29％.(5) The liquid through1kD ultrafiltration membrane possesses the best Cytology antioxidant activity and chemical oxidation resistance in vitro. the CAA value are as follows:138.5±1.81mmol QE/100mg （NO WASH） and131.2±3.907mmol QE/100mol （WASH）, the ORAC value is99.82±5.60μmol TE/100mg.