Study On Golden Jujube Peptides And Their Bioactivities

In this paper, a series of experiments were taken to get composite enzymatichydrolysis process.The result showed that jujube protein was enzyme hydrolyzed byplant protease and papain,using jujube juice concentrate liquid closure of Golden Jujubeas material. the molecular weight distribution of the mixed peptide solution wasmeasured by gel filtration chromatography; the mixed polypeptide was separated bydifferent nanofiltration membranes to two different size peptide. the hysicochemicalproperties and bioactivities were studied. The main results are as follows:The first：the optimum composite enzymatic hydrolysis process of jujube proteinUsing degree of hydrolysis as standards，jujube protein as the substrate,Throughthe single factor and orthogonal tests,the best condition of low molecular weight ofjujube polypeptide and way of enzymes adding(plant protease，papain) hydrolysis havebeen found. The result showed that hydrolysis by mixed enzymes was more efficient.theproportion of enzymes （plant protease: papain） were1:1,pH7.0,the substrateconcentration was3%，the hydrolysis time was4h. Temperature was50℃，Under theabove conditions the hydrolysis degree of protein reached26%.Second：molecular weight distribution of jujube peptideThe molecular weight distribution of jube peptide was measured by gel filtrationchromatography. The result showed: less than1355Da of Jujube peptide were almostly.The propotions of below1355Da were71.51%,1355Da-600Da32.46%were32.46%;600Da-300Da were21.36%，less than300Da were17.69%.Third：nanofiltration classification and the hysicochemical properties.The optimum conditions of the nanofiltration were, temperature30℃，materialconcentration1.5％-2％,pressure4MPa and time80min．Compared with jujubeprotein,the peptides had high solubility, thermal stability, good hygroscopicity, lowviscosity, which provided evidence for exploitation of the peptides. There was nosignificant differences between less than500Da and500Da-1000Da about thehysicochemical properties.Fourth：antioxidant activity and the hypocholesterolemic activityThe result of experiment in vivo antioxidant activity showed that differentconcentrations of jujube peptides had basic ability to clear of O2-) and OH,and theantioxidative activity of peptides was reduced as the concentration decreased. the antioxidative activity of jujube peptides became stronger as the molecular weight waslower,less than500had best scavenging activity,57.61%of scavenging rate ofO2-,92.3%of scavenging rate of DPPH,75.24%of scavenging rate of OH.The result of experiment in vitro antioxidant activity showed that the activities ofSOD, GSH-Px increased as well as T-AOC while the contents of MDA decreased inserum and the liver. jujube peptides could promoted the abilities of antioxidation ofmice. the antioxidative activity of peptides was reduced as the concentration decreased.The antioxidative activity of jujube peptides became stronger as the molecular weightwas lower.Jujube peptide could inhibit cholesterol absorption, inhibition rate was incommonly52%~52%, and the highest reached59%; The lower molecular weight, themore obvious effect on inhibition of cholesterol. the hypocholesterolemic activity ofLess than500da was best.