Study On Optimization And Rheological Analysis Of Protein Hydrolysate Produced From Zhoushan Pseudosciaena Crocea By Enzymatic Hydrolysis

This paper optimizes the process of producing salty peptides and bittern peptides from the protease hydrolysis of Zhoushan large yellow croaker,and explores the rheological properties of the salty peptides with the best saltiness and flavour and the bitterness peptide with the highest bitterness.In order to explore the optimal hydrolysis process of salty peptides,the time and pH conditions for papain hydrolyzed by large yellow croaker were analyzed and optimized by single factor and response surface methodology.Flavorzyme,pepsin,papain,alkaline protease and trypsin were used to hydrolyze large yellow croaker protein and establish a coffee bitter sensory evaluation system to find the best tool enzyme.For rheological analysis,2% hyaluronic acid(HA)and dextran coated iron oxide nanoparticles(DCIONP)were added to the two peptides in different ratios.The rheometer was used to test the experimental groups.Shear rate scans,frequency scans,and strain scans were analyzed and their effect on the rheological properties of the two peptides was analyzed.Get the following conclusions:(1)Single factor analysis showed that the highest salinity was achived when the enzyme at 3.25 h was hydrolyzed for 60 mM,while the highest flavor was achived with the enzyme at 2.8hr for 8.7.Response surface analysis showed that the optimum conditions were hydrolysis time of 3 hours,pH = 7.5,when salinity and flavor values were all at a higher level,and salinity was increased by 42 mM before hydrolysis.(2)Pepsin hydrolysis of large yellow croaker can produce the highest bitterness,equivalent to the bitter taste of 40 mg/ml mocca coffee.2% hyaluronic acid can enrich the bitter peptides in the upper solution under both static and centrifugation conditions.(3)The addition of 2% HA can significantly increase the elasticity and viscosity of peptides.The salty peptide was mixed with 2% HA in a ratio of 2:1,1:1,and 1:2respectively.Shear rate scan and frequency scan results showed that the elastic modulus?linear viscoelastic region and viscosity were the highest and the viscosity value was close to 2% HA,when mixed in a 2:1 ratio;the bitter peptide is mixed with 2% HA in a ratio of4:1,2:1,1:1,The results of shear rate sweep,frequency sweep and temperature sweepindicate that the viscosity and elastic modulus of the mixed solution was the highest and greater than the value of HA,when mixed in a 4:1 ratio.However,the continuous increase in HA concentration has a negative effect.(4)The interaction between DCIONP and peptides can increase intermolecular tangles and structural integrity to a certain degree,and it can slightly increase the elastic modulus of salty peptides.The low concentration of DCIONP mixed with the peptide solution will reduce the viscosity of the mixed solution.Although the addition of DCIONP can interact with the peptide,it does not significantly improve the viscosity and the viscoelastic modulus of the peptide mixture solution.(5)Peptides,DCIONP,HA,and each mixed system are typical viscoelastic liquids.The SEM characterization results showed that the peptide,HA,and DCIONP molecules were more closely linked to each other in the three solutions.However,rheological analysis found that this interaction does not significantly increase and change the rheological properties of the peptide.