Component Identification And Activity Of Enzymatic Hydrolysates Of Sea Cucumber Prepared By Internal And External Enzymes

Sea cucumber belongs to echinoderma,sea cucumber class,with high nutritional and economic value.Nearly 90%of the dried body wall of sea cucumber is protein.Preparation of sea cucumber peptides from sea cucumber has high commercial value.In this paper,the endogenous and exogenous enzymes were used to hydrolyze the body wall of sea cucumber.The differences of composition and physical and chemical properties of the enzymatic hydrolysis products obtained by the two methods were compared.The differences of activity and proteomics of sea cucumber autolytic peptides prepared by different reagents were compared and selected for Maillard reaction,and the physical and chemical properties and activity differences of Maillard reaction products were further analyzed.The main conclusions are as follows:(1)Sea cucumber peptides prepared by endogenous enzyme(sea cucumber autolysis)method were compared with sea cucumber peptides prepared by exogenous enzyme(neutral protease,alkaline protease and trypsin),the degree of hydrolysis of sea cucumber crude peptides prepared by autolysis method was higher,The degree of hydrolysis of sea cucumber peptides from high to low was autolysis 8 h>autolysis 4h>trypsin hydrolysis>autolysis 2 h>alkaline protease hydrolysis>neutral protease hydrolysis;the molecular weight of sea cucumber peptide prepared by autolysis was smaller than that prepared by enzymatic hydrolysis.More than 94%of the sea cucumber peptide produced by autolysis had a molecular weight of less than 314 Da,while the molecular weight of sea cucumber peptide prepared by enzymatic hydrolysis is mainly distributed in 1?7 k Da;the types of amino acids of sea cucumber peptides increased gradually with the increase of autolysis time,and the content of flavor amino acids was higher at 8 h;the sea cucumber peptide prepared by autolysis had better hydroxyl radical scavenging ability,DPPH radical scavenging ability and Fe³⁺reduction ability.(2)Sea cucumber autolytic peptides were prepared by 10%trichloroacetic acid(10%TCA)and acetonitrile,named TCA-P and ACN-P respectively.The peptide contents were 659.6 mg/g and 725.1 mg/g respectively.The molecular weight of 87%TCA-P was less than 230 Da,the molecular weight of 45%ACN-P was between13000 Da and 180 Da,and 55%less than 180 Da.TCA-P had better DPPH scavenging ability,hydroxyl radical scavenging ability,ABTS⁺,Fe³⁺reducing ability and bacteriostasis than ACN-P.233 proteins were identified by LC-MS/MS in total,and 727 and 237 peptides were identified in TCA-P and ACN-P respectively.TCA-P hydrolysis sites occurred in D(aspartic acid),E(glutamic acid)and G(glycine),and ACN-P hydrolysis sites occurred in L(leucine),G(glycine)and R(arginine).(3)The optimum Maillard reaction conditions were as follows:reaction temperature 120?,reaction time 4 h,peptide:sugar(w:w)=1:2.After the response interview of three factors and three levels,the optimum reaction conditions were as follows:reaction temperature 116.8?,reaction time 3.87 h,peptide:xylose(w:w)=1:1.95.The content of free amino acids decreased significantly and the content of high molecular weight substances increased significantly.The maximum fluorescence emission peak of Maillard reaction product moved from 400 nm to 450nm,and the UV absorption peak appeared at 290 nm.The DPPH scavenging ability,hydroxyl radical scavenging ability,ABTS⁺and Fe³⁺reducing ability of Maillard reaction products were significantly higher than those of sea cucumber autolytic peptides before the reaction.