Preparation Of Bioactive Peptides Derived From Oyster And Its Pilot Production

Oyster resource is rich in China,the consumption of oyster is mainly in fresh and dried products,the problem of lacking deep processing and product variarity is obvious.In order to further utilize marine resources,researchers have focused on low molecular weight peptides from marine organisms because of their special biological activity and safety.As typical marine product,oyster is rich in proteins,peptides,taurine and other natural active substances,which are of great market prospect.In the present study,oyster?Crassostrea gigas?was used as raw material,and its nutrients,peptide preparation process,biological activity,functional properties and pilot production were studied.The aim of this work was to provide a theoretical foundation and technical reference for effective utilization of oysters.The nutrition composition analysis showed that protein,polysaccharides and crude fat contents were 49.53%,39.64%,and 7.42%,respectively in oyster?dried?.In total amino acids,the essential amino acids and hydrophobic amino acids accounted for 32.4% and 34.3%.The desalination and sterilization results showed that the concentration of salt was decreased from4.3 g/100 g to 0.3 g/100g?wet weight?after immersing in 4 folds of ice water twice?v:w?for 2h,and bacterial colony was decreased from 4×104 CFU to 136 CFU after heating at 80 °C for 10 min.Oyster was hydrolyzed by protemax and alcalase protease through orthogonal experiment and response surface analysis.The results were evaluated by SDS-PAGE and angiotensinconverting enzyme?ACE?inhibitory activities.The first hydrolysis condition was at solid to liquid ratio of 1:4?w:v?,50 °C,pH 7.0,enzyme dosage of 1.2% protemax,with hydrolyzing duration of 60 min.The second hydrolysis condition was at 53 °C,pH 8.3,enzyme dosage of0.42% alcalase,with hydrolyzing duration of 73 min.The polysaccharide degradation results indicated that the 1,4-D-glucan glucohydrolase performed better than ?-amylase,carrageenase and abalone visceral enzyme.At the same time,decolorization and deodorization results indicated that the ultrafiltration membrane worked better than other methods.The decolorization rate was 97% and the yield of peptide was 85%.The filtrated peptide was then spray-dried.The basic characters and biological activities of peptide prepared were analyzed.High performance liquid chromatography?HPLC?analysis showed that almost all?99.72%?the peptides were with molecular weight less than 3000 Da.The power was pale yellow,L* value was 85.66,a* value was 1.47 and b* value was 24.61.Biological activities showed that the half scavenging effect?IC50?of ACE inhibitory activity,DPPH· and ·OH scavenging ability and Fe²⁺chelating ability were 0.8,3.3,6.8,and 1.5 mg/mL,respectively,and reducing power reached 1at a concentration of 4.5 mg/mL.In vitro simulated gastrointestinal digestion revealed that the peptides were stable after digestion.In addition,the water absorption ability of peptide power was 0.56 g/g and oil absorption was 1.10 g/g.Its emulsifying ability was 170 cm2/g and emulsion stability was well at pH 5 and 10.A pilot production of oyster peptides was carried out in a GMP workshop.The results showed that the yield of oyster peptide was 56.7 %,the peptide power was pale yellow.And the half scavenging effect?IC50?of ACE inhibitory activity and DPPH·scavenging ability was 1.7mg/mL and 4.5 mg/mL,respectively.Study on the characteristic of oyster peptide revealed no significant difference with the laboratory scale including sensory properties,peptide yield and biological activity.These results indicated that the method of pilot scale production was feasible and suitable.The present study would provide a theoretical foundation and technical reference for high-value utilization of oysters.