Study On Prepartion And Activity Of ACE Inhibitory Peptide From Corn Gluten Meal

Corn gluten meal is the main by-product of wet processing of maize.It contains about 60%protein,of which zein accounts for about 68%.Zein contains a high proportion of hydrophobic amino acids such as proline,alanine and leucine.Through enzymatic hydrolysis,many kinds of active peptides can be prepared,such as antioxidant,sobering,lowering blood pressure,etc.However,due to the high content of protein components,the existence of hydrophobic amino acids also leads to poor water solubility of raw materials,and the enzymatic hydrolysis efficiency is very low in water solution environment.In order to improve the efficiency of enzymatic hydrolysis and the inhibition of blood pressure by enzymatic hydrolysates,the effects of enzymatic hydrolysis of corn gluten meal assisted by ultrasound and ultra-high pressure on enzymatic hydrolysis characteristics were studied in this paper.The main results are as follows:1.The hydrolysis effects of alcalase protease,neutral protease,compound protease,trypsin and protamex on CGM were studied.ultrasound-assisted hydrolysis of CGM with neutral protease was selected to study the effects of ultrasonic power,substrate concentration,enzyme concentration,pH,reaction time and reaction temperature on hydrolysis and ACE inhibitory activity of hydrolysate.The optimum technological parameters of ultrasonic-assisted neutral protease hydrolysis of CGM were determined as follows:substrate concentration 5.00%,temperature 45?,enzyme concentration0.6×10~4U/g substrate,pH 7.2,enzymatic hydrolysis time 1.0h,ultrasound power 480W.Under these conditions,the inhibition rate of ACE of enzymatic hydrolysate was(63.37±0.19)%.2.The ACE inhibition rate of hydrolysate was compared among groups,which were ultrahigh pressure(UHP)assisted enzymatic hydrolysis,enzymatic hydrolysis after ultrahigh pressure pretreatment and enzymatic hydrolysis under atmospheric pressure.The effects of substrate concentration,time,pressure,pH and temperature on the inhibition rate of ACE were discussed.The preparation conditions were optimized by response surface methodology.The ACE inhibition rate of UHP assisted enzymolysis was increased by 55%compared with atmospheric pressure,and 30% higher than the group with ultrahigh pressure pretreatment.According the results,pH was the main factor,followed by pressure,substrate concentration and time,the effect of temperature is not obvious.The results indicated that the ACE inhibition rate could be up to(74.03±0.56)%under the optimized enzymatic hydrolysis conditions,which were substrate concentration of 4.78%,high pressure time of14min,pressure of 372MPa,pH of 8.4.ACE inhibitory peptides from CGM were prepared by the ultrahigh pressure-assisted Alcalase enzymolysis,which improved the activity of inhibitory peptides and shortened the enzymatic hydrolysis time.3.The effects of ultra-high pressure on the properties of enzymatic hydrolysates of corn gluten meal were studied.After ultra-high pressure treatment,the structure of CGM becomes more loose;ultra-high pressure makes the structure of protein in CGM become more loose,which is more conducive to the enzymatic molecules entering the protein particles and acting,so that a large number of hydrophobic amino acids are released,thereby improving the ACE inhibitory activity of enzymatic hydrolysates.4.Under the same enzymatic hydrolysis time,compared with atmospheric hydrolysis,ultra-high pressure assisted enzymatic hydrolysis can promote enzymatic hydrolysis efficiency,increase the content of small and medium molecular weight peptide segments of enzymatic hydrolysis products,and improve the surface hydrophobicity of enzymatic hydrolysis products.Under the same enzymatic hydrolysis time,ultra-high pressure pretreatment and ultra-high pressure assisted enzymatic hydrolysis can increase the proportion of hydrophobic amino acids of enzymatic.