Preparation Of Antihyertensive Peptides Isolated From Soy Protein Isolate With Utrasonic Assisted Zymohydrolysis

Soy protein isolate for the raw materials preparation ACEIP by ultrasound treatment, as well as the mechanism and the dynamics of soy protein isolate by ultrasound of the study are as follows:Protein enzyme was selected from 7 ones,and alkaline protein enzymes（Wuxi） showed the better inhibitory effect.The effects of hydrolyzation time,substrate concentration,enzyme amount,temperature,pH were evaluated to inhibitory activity and orthogonal experimental validation,drawn optimal hydrolysis conditions were as follows:reaction temperature 50℃,reaction time 90min,add enzyme was 0.08mL/g, substrate concentration of 6%,pH value of 8.5.Soy protein isolate was preteated by ultrasound,alkaline protease was treated by ultrasound and ultrasound was imposed on the process of enzyment,those three different enzymatic processes have been compared.The result was that the pretreatment of soy protein isolate was the best process:ultrasonic pretreatment time 30min, ultrasonic temperature 50℃,ultrasound power 400W/L and inhibition rate was 90.29% under the best parameters.Secondly,alkaline protease activity was increased by ultrasound treatment.Protease activity was the largest for 6.89%when treatment time 10 min,power 1200W/L.Thirdly,ultrasound was imposed on the process of enzyment and ACE enzyme inhibition rate increased sightly.ACE enzyme inhibition rate increased only 2.2%when power 800W/L,but the inhibition rate decreased significantly when power increased continuely.The surface structure and nature of soy protein isolate changes by ultrasound cycle treatment.The surface hydrophobicity,free sulfhydryl content,solubility,emulsifying and foaming of soy protein isolate by ultrasound were as follows:When the ultrasonic power 400W/L,the maximum surface hydrophobicity,as compared with non-ultrasound treatment increased by 39%;When 750W/L sulfhydryl content received an increase of 12%at the highest compared with non-ultrasound treatment;When the ultrasonic power 500W/L,the maximum protein solubility increased 1.3 times compared with non-ultrasound treatment of the samples.Study on dynamics of soy protein isolate by ultrasonic treatment and determine the Vmax and K_m.Ultrasonic improved the speed hydrolysis,K_m and V_max respectively increased by 83.7%and 76%compared to non-ultrasound treatment.The optimal pH and temperature were determined from mechanism and pH9.05 and 50℃were the best theoretical value...