Preparation Of Antioxidant Peptides By Proteolysis The Meat Of Lizard Fish

In the normal metabolism of the human body,biologically active free radicals will be produced.Excessive free radicals or too slow free radical scavenging may accelerate the processes of aging and induce inflammation,immune disorders,malignancies and other diseases.In addition,artificial antioxidants often have side effects,and long-term intake artificial antioxidants can lead to a range of diseases,such as liver damage and tumors.However,the antioxidant peptides of marine biological protein sources can effectively eliminate endogenous and exogenous free radicals,and have many varieties and few side effects,are expected to become safe and efficient natural antioxidants.The lizard fish is one of the economic fishes of the Guangxi Beibu Gulf,and it has a large annual output.As a kind of fish that is difficult to preserve after fishing in the ocean.And it often regarded as waste or low-value feed during processing,which greatly reduces the use value of lizard fish and causes certain environmental pollution.The preparation of bioactive peptides from lizard fish protein can provide a theoretical basis for product development of industrial lizard fish resources.To test the antioxidant properties of different protease hydrolysates under different enzyme hydrolysis times,that the six different commercial proteases were used to hydrolyze lizard fish meat protein.And the free radical scavenging activity of 1,2-dipicyl-2-trinitrophenylarylene free radicals(DPPH),Pyrogallol superoxide free radicals(O2-·)and Fe3+ reducing ability were used as indicators.The results showed that the trypsin hydrolysate has the best scavenging activity,when the degree of hydrolysis(DH)of the trypsin hydrolysate was 13%.And at the protein concentration of hydrolysate with 1 mg/L,the scavenging activity of DPPH-,O2-·and Fe3+ reducing ability is 91.41%,19.64%and 1.08 Abs,respectively.The optimal enzymatic hydrolysis conditions for the enzymatic hydrolysis the meat protein of lizard fish were:enzyme dosage 8000 U/g,pH 7.0,temperature 40 ?,substrate concentration 25 g/L,hydrolysis time was 2 h and the degree of hydrolysis(DH)was 13%.After hydrolyzed lizard fish meat under optimized process conditions,the molecular weight distribution of the hydrolyzed product was analyzed by gel filtration chromatography,and the enzymatic hydrolysate was separated by microfiltration and ultrafiltration.The ultrafiltration membranes of 10KDa and 5KDa were used for the collect of hydrolysates with different scavenging activity.And it was found that the ultra-filtered permeate of the hydrolysate of lizard fish meat protein which molecular weight of less than 5 kDa had strongest antioxidant activity.The antioxidant activity of DPPH-,O2-·and Fe3+reducing ability was 94.45%,44.54%and 1.32 Abs with the protein concentration of hydrolysate at 1 mg/L,respectively.And the amino acid composition analysis of the enzymatic hydrolysate which molecular weight of less than 5 KDa was carried out by reversed-phase high performance liquid chromatography.It's contains the following 14 amino acids:aspartic acid,glutamic acid,glycine,threonine,alanine,arginine,tyrosine Cysine,Proline,Methionine,Tryptophan,Phenylalanine,Isoleucine,Leucine,proline.The enzymatic hydrolysate protein from the meat of lizard fish with molecular weight less than 5KDa was used as the peptide source.And the zinc ion chelation rate was used as the indicator to investigate the effect of peptide zinc mass ratio,reaction time,reaction system pH and reaction time on the chelation rate.The optimal chelation conditions were:peptide zinc mass ratio is 2:1,temperature at 45 ?,pH=6.5,chelation time with 60 min,maximum chelation rate obtained by confirmatory experiment:89.23%.And the result showed that the antioxidant capacity of hydrolysate is enhanced after chelating zinc ion.At a protein concentration of the hydrolysate with 1 mg/L,the antioxidant activity of DPPH·,O2-· and Fe3+reducing ability is 97.59%,69.13%and 1.72 Abs,respectively.