Enzymatic Preparation And Prefractionation Of ACE Inhibitory Peptides From Rice Bran Proteins

With the global hypertension rates becoming more and more higher,Attention to antihypertensive peptide also more and more higher to become a effective way of boycott hypertension.China is a big country of rice production,resources of rice bran was rich,and annual output of rice bran was about one third of the world,but most rice bran were simply used as feed,development and utilization had not been paid enough attention.Because of reasonable amino acid composition,hydrophobic amino acids and higher proportion of aromatic amino acids,high biological utilization rate,less antinutritional factors and so on,rice bran proteins becomes good protein resources of biological active peptides.With rice bran protein as raw materials,preparing rice bran ACE inhibitory peptides with enzymatic method,not only could make full use of rice bran resources,and reduce environmental pollution,but also could produce high value-added products,and had significant economicand social benefit.In this experiment,rice bran protein was used as raw material,enzymatic method was applied to prepare ACE inhibitory peptides.Main contents and results are as follows: alkali protease,Alcalase2.4L,neutral protease,papain,trypsin and pancreatic curd protease and proteinase K were selected to hydrolyze rice bran protein,With ACE inhibition ratio as index,the best was determined.Sure enzyme for test was Alcalase2.4 L.Through single factor experiment,pH,substrate concentration,hydrolysis temperature,hydrolysis time and enzyme concentration to affect ACE inhibitory activity and hydrolysis degree on the product were respectively investigated,The appropriate value of each factor was identified as follows: pH 8.0,substrate concentration 3.0%,hydrolysis temperature 50℃,hydrolysis time 120 min and enzyme concentration 3000 U/g.With quadratic orthogonal rotation combination test design optimizing the process parameter of enzymatic hydrolysis,The optimum conditions of preparing rice bran protein ACE inhibitory peptides with enzymatic hydrolysis was got that hydrolysis temperature 62℃,substrate concentration 3.6%,enzyme concentration 3567 U/g,hydrolysis time 106 min,pH 8.5,Under this condition,ACE inhibitory rate of the rice bran protein ACE inhibitory peptides was 78.3%.In order to effectively control the hydrolysis degree to guide the production practice,based on the above study,the hydrolysis process of rice bran proteins using Alcalase 2.4 L was studied,and the enzyme hydrolysis dynamic model was established.Enzyme hydrolysis dynamics model was as follows:R =(94.754 E0-0.0597)S0 exp [0.157(DH)] and DH = 6.37 ln [1 +(14.88 E0 / S0-0.009)t],including dynamics constant a=94.754E0/S0-0.0597,b = 0.157,k2 = 94.754 min-1,enzyme inactivation constant for 16.144 min-1.Macroporous resin DA201-C was select and suitable for desalination of rice bran ACE inhibitory peptides.Under the condition of liquid concentration sample 20 mg/mL,ethanol concentration 70 %,the rate of sample 1.5 BV/h,elution velocity of 1.5 BV/h,analytic and adsorbable effect of DA201-C resin were best.Ultrafiltration was selected to preliminarily separate rice bran ACE inhibitory peptides after desalination,under the condition of material concentration 3%,pH 7.0,pressure 0.15 MPa,temperature 40 ℃,with ultrafiltration membrane of 5 KDa and 1 KDa,rice bran ACE inhibitory peptide component with relative molecular mass of less than 1 KDa was got and it was the strongest inhibitory activity to ACE;The Sephadex G-15 gel chromatography was applied to further separate the component with relative molecular mass of less than 1 KDa,Gel patterns appeared two peaks,ACE inhibited activity of two kinds of component was determined that inhibitory activity to ACE of RBH1 was 90.3 %,inhibitory activity to ACE of RBH2 reached93.1%.