Study On Preparation And Antihypertensive Activity Of Corn Short Peptides

Corn gluten meal is the main by-product in the corn starch production.Generally,it is used as animals’ feed.Corn gluten meal were used as raw material in this paper,ultrasonic-assisted extraction of zein,hydrolysis of zein,membrane separation of corn short peptides,antihypertensive activity in vitro and vivo were studied.The main results are as follows:1.Response surface methodology was used to optimize the extraction of zein from corn gluten meal.The results showed that the optimal extraction conditions were as follows:ultrasonic time was 27 min,ultrasonic power was 480 W and alcohol concentration was 70%with the ratio of liquid to material 10:1(mL/g).Under the optimal extraction conditions,the extraction rate of zein was up to 70.71%and the purity was 90.33%.2.Uniform design was used to optimize the single enzyme hydrolysis conditions.The optimum conditions for the hydrolysis of zein were as follows:Alcalase 2.4L FG:pH 8.5,T 55℃,E/S 80 mAU/g,123 min;Neutrase 1.5MG:pH 7.0,T 50℃,E/S 46 mAU/g,135 min;Pepsin:pH 2,T 25℃,E/S 7341 U/g,66 min.three kinds of proteases were compound to hydrolysate zein.The results indicated that compound enzymes hydrolysis had better effect than single enzyme.Hydrolysis order Alcalase+Neutrase+Pepsin had highest DH 18.95±0.57%.Concentration of short peptides in zein hydrolysates was 10.25 ± 0.48 mg/mL,the yield of short peptides was 24.55±0.88%.3.Zein hydrolysates were refined by ultrafiltration and nanofiltration.The optimal conditions for utrafiltration were pressure 0.16MPa,operation temperature 45℃.Using constant volume ultrafiltration model,when added 3 times distilled water,the transmittance of short peptides was 76.22 ± 1.82%.Mainly Distribution of molecular weight of zein hydrolysates through 1KDa membrane was 200-400 Da.At room temperature,pressure 1.5MPa,Using the concentrated-dilution-concentrated nanofiltration desalination model,when added deionized water 5 times,desalination rate was 88.05%,the peptides intercept rate was 93.75%.It was found that IC50 and ORAC value of zein hydrolysates were 1.79 mg/mL,548.42±82.22μM Trolox/10mg,respectively.After membrane separation,its IC50 and ORAC value was 0.63mg/mL、648.82±112.53μM Trolox/100mg,respectively.4.IC50 and ORAC value of corn short peptides freeze-dried powder was 0.49 mg/mL,726.96 ±59.77 μM Trolox/100mg.Animal experiments studied effects of different doses on blood pressure of spontaneously hypertensive rats(SHR).Compared with control group,the medium(1.5g/kg BW)and high(2g/kg BW)dose group had reduced 16.4 mmHg,22.7 mmHg,respectively at 4h after oral administration.After 12 h,SHR’s blood pressure at different doses had no significant differences compared with control group.