Effects Of Different Pretreatment On The Physicochemical Properties And ACE Inhibitory Activity Of Ovalbumin

Ovalbumin modification mainly includes physical methods,chemical methods and enzymatic methods.By changing the internal structure and characteristics of proteins,the biological activity of ovalbumin can be improved or enhanced.ACE inhibitory activity is a research hotspot at home and abroad.It can regulate human blood pressure,thereby inhibiting physical diseases caused by high blood pressure.Therefore,in this experiment,ovalbumin was mainly used as the research object.Ovalbumin was treated by temperature,p H,and metal ions to study the changes in the physicochemical properties of the treated protein and the protein before treatment and the ACE inhibitory activity.The main findings are as follows:(1)The physicochemical properties of ovalbumin such as particle size,Zeta potential,sulfhydryl content,endogenous fluorescence,surface hydrophobicity,as well as the degree of hydrolysis of ovalbumin and ACE inhibitory activity after enzymatic hydrolysis were studied at different temperatures.The results show that the particle size distribution of ovalbumin changes with the increase of heat treatment temperature.The average particle size increases first and then decreases,from 622.73±4.60 nm to 1527.00±59.40 nm,and then to 261.64±2.26 nm;The absolute value of Zeta potential increases from 6.56±0.36 m V to 19.20±0.62 m V;the surface sulfhydryl content increases from 2.20±0.37?mol/g to 23.76±0.71?mol/g,the total sulfhydryl content decreases first and then increases,from 9.63±0.26?mol/g decreased to 6.46±0.16?mol/g,and then increased to 29.55±1.88?mol/g;the maximum absorption peak of endogenous fluorescence was blue shifted by 1 nm;the surface hydrophobicity value increased first and then decreased,from249.52±0.49 increases to 274.32±1.19,then decreases to 135.17±14.81;the degree of hydrolysis increases first and then decreases,reaching 28.62±0.42%at60?;ACE inhibitory activity increases to varying degrees,ACE at 80?The inhibitory activity reached 79.17±0.54%,which was 23.01%higher than that of the untreated solution.The temperature has a greater influence on the molecular weight distribution of the enzymatic hydrolysis products at 80?and 90?.When the temperature is 80?,the proportion of molecular weight between 944 and 636 Da is increased from 8.38%to 41.12%,and the proportion of molecular weight<264 Da is reduced from 71.19%to 41.67%.When the temperature is 90?,the proportion of molecular weight between 944 and 636 Da is increased from 8.38%to 24.82%,and the proportion of molecular weight<264 Da is reduced from 71.19%to 46.47%.(2)The physicochemical properties of ovalbumin particle size,Zeta potential,sulfhydryl content,endogenous fluorescence,surface hydrophobicity,etc.under different p H conditions,as well as the degree of hydrolysis of ovalbumin and ACE inhibitory activity after enzymatic hydrolysis were investigated.The experimental results show that as the p H value increases,the particle size distribution of ovalbumin changes,and the average particle size decreases from 615.30±19.66 nm to 347.45±55.93 nm;the absolute value of Zeta potential increases from-5.76±0.57 m V increased to-23.1±2.55 m V;sulfhydryl content increased,surface sulfhydryl content increased from 0.68±0.06?mol/g to 1.31±0.08?mol/g,total sulfhydryl content increased from 7.42±0.70?mol/g to 10.25±0.70?mol/g;the endogenous fluorescence intensity increases and the maximum absorption peak occurs 1 nm red shift;the surface hydrophobicity value decreases from 305.50±6.86 to 269.62±13.42;the degree of hydrolysis increases to varying degrees when the p H is 10 It reached 33.83±3.98%;the ACE inhibitory activity increased with the increase of p H,and reached 69.40±5.93%when the p H was 10.It is p H=6 and p H=10 that p H has a great influence on the molecular weight distribution of enzymatic hydrolysis products.When p H=6,the proportion of molecular weights in all four sections changes significantly.The proportion of molecular weights between4012 and 944 Da decreases from 16.54%to 1.57%,and the proportion of molecular weights between 944 and 636 Da increases from 8.38%to 44.21%,the proportion of molecular weight between 636 and 264 Da increased from 3.89%to 17.49%,and the proportion of molecular weight of<264 Da decreased from 71.19%to 36.73%.When p H=10,the molecular weight ratios in the three intervals all changed significantly.The proportion of molecular weights between 4012 and 944 Da decreased from 16.54%to 2.66%,and the proportion of molecular weights between944 and 636 increased from 8.38%to 59.13%,the proportion of molecular weight in<264 Da decreased from 71.19%to 32.57%.(3)When adding different metal ions to the protein solution,the physical and chemical properties of ovalbumin particle size,Zeta potential,sulfhydryl content,endogenous fluorescence,surface hydrophobicity,as well as the degree of hydrolysis of ovalbumin and ACE inhibitory activity after enzymatic hydrolysis were investigated.the study.The experimental results show that when different metal ions are added to the solution,the particle size distribution of ovalbumin changes,the peak intensity of 0-100 nm increases,and the peaks between 100-1000 nm shift to the left,And the peak intensities are weakened in different sizes;the average particle size is significantly reduced,from 859.85±47.73 nm to 213.15±18.31 nm;the absolute value of Zeta potential is significantly reduced,from 6.60±0.04 m V to2.29±0.25 m V;The surface mercapto group content is reduced,but the effect is not significant;the total mercapto group content is reduced,and when Ca²⁺is added to the solution,it is reduced from 9.50±0.15?mol/g to 7.27±0.29?mol/g;the fluorescence intensity of endogenous fluorescence is enhanced,However,the maximum absorption peak(?max)did not change significantly when Na⁺and K⁺were added.When Ca²⁺and Mg²⁺were added,the maximum absorption peak was red-shifted by 1 nm;the surface hydrophobicity value was significantly reduced,and when Mg²⁺was added to the solution,from 305.88±4.89 reduced to 209.85±9.13.The experimental results show that the addition of metal ions can inhibit the hydrolysis of protein solution.When Na⁺,K⁺and Mg²⁺are added to the solution,the degree of protein hydrolysis can be significantly reduced,and when K⁺is added to the solution,the decrease is from 23.31±0.42%.To 9.74±0.42%.The ACE inhibitory activity on protein hydrolysate was not effectively improved,but the ACE inhibitory activity of hydrolysate was reduced.