Study On Manufacture Of Bioactive Peptide From Oceanic Fish Protein By Controlled-enzymatic Hydrolysis

In this paper, studies on preparation of biologically active peptides by use of controlled-enzymatic hydrolysis of sardine protein, ultrafiltration and ion-exchange, and anti-fatigue action were carried out.Studies of controlled-enzymatic hydrolysis were mainly on the effect of pH, hydrolyzed time, dosage and varieties of proteases, concentration and varieties of substrate, hydrolyzed temperature and stirring mode on hydrolyzed result and distribution of molecular weight. Experimental result is as follows.Basis on change of pH has little effect on recovery ratio of peptides and distribution of molecular weight, there is no need to add alkali to keep pH constant during hydrolysis. The course of hydrolysis may be divided into three stages. They are quick raise-stage, slow increment-stage and plateau-stage, and the main reason to that is the decrease of concentration of substrate. As hydrolyzed time goes on, peptide chain length of hydrolysates will decrease, the content of high molecular weight will decline, and on contrary, the content of low molecular weight will rise. The best hydrolyzed result is Trypsin, and then is Alcalase and Protamex, the worst is Neutrase. The optimum dosages of four kinds of proteases are all 2000U/g³000U/g. Too high beginning substrate concentration will decrease the velocity of hydrolyzed reaction. The optimum beginning substrate concentration is 7.5%. The hydrolyzed result of sardine is better than of nemipterus. The optimum hydrolyzed temperature of Trypsin and Alcalase is about 55°C, the optimum one of Protamex and Neutrase is 50°C around, and the optimum temperature of auto-hydrolysis is 45℃ The hydrolyzed result by continuous stir is more better. The beginning concentration and the variety of protease and substrate will have notable effect on relationship between degree hydrolysis and recovery ratio of nitrogen and peptide.The kinetic model and relative parameter of controlled-enzymatic hydrolysis are obtained by use of mathematic deduction and experimental analysis. The result is as follows: the kinetic model formula is DH = 9.804In[1 +(1.701E₀/S₀ -0.00367)t] andR = (16.678E₀-0.036S₀)exp[-0.102(DH)]; the kinetic parameter is k₂ = 16.678mm^-1 andk_d = 1.7015min^-; the lowest, critical and beginning concentration of protease is E₀ = c₀S₀ ; and the highest, critical and beginning concentration of substrate is S₀=E₀/c₀, and c₀ = 2. 159× 10^-3The study on ultrafiltration showed that the average filtrating rate, membrane...