Study On Preparation And Antioxidant Activity Ofcollagen Peptide From Sea Cucumber

The main nutrients of Acaudina molpadioidea was studed in this research.Sea cucumber collagen was isolated by hot water,the composition,viscosity and solubility of it were researched.Collagen peptides were extracted from the body wall of Acaudina molpadioidea by enzyme,and the method of peptide preparation was optimized.The separation and purification and the antioxidant activity of collagen peptide was researched.The experimental results show that:On the analysis of Acaudina molpadioidea body wall,the crude protein content was?73.28±2.20?%?dry weight?,the content of hydroxyproline was 41.89±0.41 mg/g and total sugar content was?13.48±0.46?%?dry weight?.According to the conversion,the content of collagen in the Acaudina molpadioidea body wall is 56.56%,accounting for 77.18%of total protein,it means that mainly of protein in the body wall was collagen.The collagen prepared by hot water shows high purity.Through analysis,the conten of crude protein,collagen and total sugar were?95.57±0.91?%,?93.09±0.1?%,?84.31±1.3?%,respectively.The collagen viscosity study found that temperature and collagen concentration has a great influence on the collagen solution viscosity.In general,viscosity with temperature rise and fall;the viscosity rise with the concentration of collagen increased.Solubility research showed that the pH and the concentration of NaCl could affect collagen solubility.Solubility of collagen presents the rising trend between pH 2.0-7.0,while decreased in pH from 7.0 to 10.0.Collagen solubility without much change in low concentration of NaCl,but high concentration NaCl reduce its solubility.The results of Acaudina molpadioidea collagen UV scan showed that collagen extracted by hot water had higher purity,and the maximum absorption peak of it was at210nm;infrared analysis showed the well preserved structure of collagen.Experiment selects trypsin,neutral protease and papain to prepare collagen peptide,by comparing the extraction ratio,found that trypsin is the best,peptides extraction ratio was?42.66±1.51?%.In factor tests,all the factors had effect on hydrolysis.In all,pH showed less influence,extraction ratio of peptides just rose to?36.69±0.06?%from?33.82±0?%,when pH from 6.0 to 8.0.Through L₉?3⁴?orthogonal experiment,temperature showed the most influential on extraction ratio,followed by enzymatic quantity and time,pH effect was not significant.Considering the cost,this research slected A2B2C3D1 to hydrolyze the body wall,rather the best one A₃B₂C₁D₃.The enzymatic hydrolysate was seprated to three parts,P1?>5 kDa?,P2?1-5 kDa?,P3?<1kDa?,by ultrafiltrate?1 kDa,5 kDa?.Hydroxyl free radical scavenging research showed that low molecular peptide weight has stronger activity.The effect of three parts on hydroxyl free radical scavenging was P1<P2<P3,among them,P2 had little difference with P3,the scavenging rate was?93.42±1.03?%,?94.77±1.27?%,respectively.The peptides,molecular weight under 5 kDa,was seprated to two main peaks by Sephadex G-25,which shows that contained small molecular weight peptides more.The antioxidant activity of collagen peptide and collagen was estimated by the scavenging rate of·OH,O₂^-·and DPPH·,V_C was used as contrast group.Collagen peptide and collagen both had good radical scavenging activity.Under the same concentration,the scavenging activity of collagen to three kinds of radical was O₂^-·>DPPH·>·OH,the ratio was?44.66±0.86?%,?42.75±0.28?%,?24.42±0.41?%,respectively.In the other way,the scavenging activity of collagen peptide to three kinds of radical was DPPH·>·OH>O₂^-·,the ratio was?52.81±0.27?%,?23.83±0.47?%,?12.49±1.06?%,respectively.In general,the collagen peptide antioxidant activity is better than the collagen.The scavenging effect,strong to weak,on·OH was collagen peptide>collagen>V_C;on O₂^-·was V_C>peptide>collagen;on DPPH·was peptide>V_C>collagen.