Preparation Of Bioactive Peptides From Tuna Muscle Protein Enzymolysis

The world's ocean fisheries production was over 8.5 million tons in recent years,more than 6 million tons was tuna production,accounting more than 70 percent of fisheries production,Thus,tuna become one of the important fishing species in world's ocean fishing.Tuna muscle is good at tasting,with high protein,low in fat and rich in minerals,vitamins or polyunsaturated fatty acids.Since the tuna fishery started late in our country,the tuna by-products have not been developed and used.Due to the hard in processing and recycling,these by-products had been just discarded,which bring resources wasting and environmental pollution.The study was prepared bioactive peptides from tuna muscle enzymolysis by protease,and provide a theoretical basis to improve the use of tuna by-products and developing high value-added products.Four enzymes,Serratia protease,papain,neutrase and trypsin were used to hydrolyse tuna muscle protein.Based on the DPPH radical scavenging rate,the best enzyme was trypsin.Using different molecular weight cutoff ultrafiltration membrane to divide enzyme hydrolysates into four components.The molecular weight below 3 kDa showed the highest DPPH radical scavenging activity.Single factor and orthogonal experiments were adopted and the optimum enzyme hydrolysis conditions were obtained as follows:pH was 8,temperature 37?,time duration was 2 hours,liquid-solid ratio was 5:1.At this condition,the DPPH radical scavenging activity of this part was 87.62%,IC₅₀ was0.613 mg/mL,peptides content was 16.6%.Sephadex G-25 gel column chromatography was used to purification the hydrolysates which molecular weight below 3 kDa.Discussing the influence of eluent,flow rate and the sample volume on separation.The optimum condition was using ultrapure water as eluent,flow rate was 0.5mL/min,the sample volume was 1 mL.At this condition,the hydrolysate was divided into three components.The Gly,Cys,Lys,GSSH and bovine serum albumin as standard to obtain a standard curve for molecular weight distribution analysis,identify the molecular weight of three components were:1056.02 Da?190.81 Da and 60.98 Da.Four enzymes,Serratia protease,papain,neutrase and trypsin were used to hydrolyse tuna muscle protein.Based on the ACE inhibition rate,the best enzyme was trypsin.Using different molecular weight cutoff ultrafiltration membrane to divide enzyme hydrolysates into four components.The molecular weight below 3 kDa showed the highest ACE inhibition activity.Single factor and orthogonal experiments were adopted and the optimum enzyme hydrolysis conditions were obtained as follows:pH was 8,temperature 37?,time duration was 2 hours,liquid-solid ratio was 5:1.At this condition,the ACE inhibition rate of this part was 83.46%,DH was 13.68%.