Study On Enzymatic Hydrolysis Conditions Of Pea Protein And Antioxidant Activity Of The Hydrolysates

The aim of this article was to explore the effect of pretreatment of extrusion on the functional properties and structure of pea protein,to optimize the enzymatic conditions of pea protein and determine the antioxidant activity of the hydrolyzate,and to isolate and determine the properties of hydrolyzate.The application of pea protein and its extruded products and the development of noodle products were studied.The pea protein was pretreated by extrusion and enzyme co-extrusion.The solubility,degree of hydrolysis,emulsification,emulsion s Tableility,foaming capacity and foam s Tableility of quality indicators of extrudate were evaluated.When the water content of the pea protein was 25%,the quality of the extrudate was the best,and when the water content of the pea protein was 30%,the quality of the neutral protease co-extruded product was the best.The effect of pretreatment of extrusion on pea protein was further studied by measuring the microstructure,disulfide bond,secondary structure,functional group and amino acid composition of the optimal substrate.The study found that the extrusion and enzyme co-extrusion could significantly change the microstructure of pea protein,reduce the content of disulfide bond,change the content of secondary structure and the composition of amino acids,but no change to the functional group.Based on response surface method,the optimal conditions for enzymatic hydrolysis of pea protein and the extrudate of pea protein by neutral protease and papain were evaluated by the scavenging rate of DPPH,.OH,and O₂.^-.The optimal conditions for the enzymatic hydrolysis of pea protein by neutral protease were as follows:enzyme concentration（E/S）of 10.6%and a temperature of 40.3℃,p H 7.02,substrate concentration（g/ml）of 6.80%.Under this condition,the scavenging rate of DPPH,.OH,O₂.^-were 99.1%,97.6%and 78.1%.The optimal conditions for the enzymatic hydrolysis of pea protein by papain were as follows:enzyme concentration（E/S）of 12.1%and a temperature of 60.2℃,p H 6.46,substrate concentration（g/ml）of 7.2%.Under this condition,the scavenging rate of DPPH,.OH,O₂.^-were 98.2%,58.5%and 64.0%.The optimal conditions for the enzymatic hydrolysis of the extrudate of pea protein containing 25%moisture by neutral protease were as follows:enzyme concentration（E/S）of11.8%and a temperature of 37.5℃,p H 6.90,substrate concentration（g/ml）of 8.00%.Under this condition,the scavenging rate of DPPH,.OH,O₂.^-were 95.4%,88.3%,and 55.2%.The optimal conditions for the enzymatic hydrolysis of the extrudate of pea protein containing 25%moisture by papain were as follows:enzyme concentration（E/S）of 12.1%and a temperature of60.6℃,p H 6.50,substrate concentration（g/ml）of 7.10%.Under this condition,the scavenging rate of DPPH,.OH,O₂.^-were 98.3%,84.7%,and 76.3%.The optimal conditions for the enzymatic hydrolysis of the neutral protease co-extrudate of pea protein containing 30%moisture by neutral protease were as follows:enzyme concentration（E/S）of 12.2%and a temperature of 40.2℃,p H 6.99,substrate concentration（g/ml）of 6.92%.Under this condition,the scavenging rate of DPPH,.OH,O₂.^-were 98.2%,82.3%,and 75.9%.The optimal conditions for the enzymatic hydrolysis of the neutral protease co-extrudate of pea protein containing 30%moisture by papain were as follows:enzyme concentration（E/S）of 12.0%and a temperature of 60.2℃,p H 6.50,substrate concentration（g/ml）of 7.10%.Under this condition,the scavenging rate of DPPH,.OH,O₂.^-were 98.1%,73.9%,and 67.1%.The separation and determination of molecular weight of enzymolysis products were studied by the method of dialysis bag and HPLC.The enzymolysis liquid was separated（<1KDa,1-3.5 KDa,3.5-7 KDa,<7 KDa）,and found that the antioxidant activity of enzymolysis liquid less than 1KDa was the strongest.And the effect of pea protein and the best extrusion of pea protein on the quality of noodles was studied.The study found that the quality of noodles were improved siginificantly with the addition of pea protein and extrusion of pea protein,through determining the cooking quality,texture characteristics,and sensory evaluation of the noodles,and the quality of noodles were the best when the content was 6%.