Studies on Plastein Reaction of Tilapia By-Priducts Protein

Hydrolyzed proteins were prepared by Alcalase from Tilapia by-products protein in this study.Degree of hydrolysis was controlled at 40 %,and plastein reaction was studied from hydrolyzed proteins by pepsin.Flavor of plastein reaction products and yield of plastein synthesis was determined under different conditions,and the optimum conditions were optimized by response surface analysis methodology.The results showed that substrate concentration of 31.76 %,quantity of added enzyme of 2.92 %,pH 4.95,temperature of 37 ℃ and synthesis period of 24 h were selected as the optimal conditions of plastein synthesis from hydrolyzed Tilapia by-products protein.In the above mentioned optimal conditions,integrated flavor score of system was 2.56±0.02,and plastein yield was(8.96±0.11) %.These were not significant different with the model prediction(2.54,8.99 %) and flavor of reaction products was improved significantly(p0.05).The results of SDS-urea-PAGE and HPLC analysis showed that plastein reaction was a process with increasing of molecular weight,and macromolecular proteinoid with larger molecular was generated by condensation reaction of polypeptide and amino acids with small molecule weights.