Study Of Preparation, Separation And Purification Of Walnut Protein ACE Inhibitory Peptide

Walnut protein can obtain small molecule polypeptide by protease hydrolysis under mild conditions,these small molecule consumption of high safety,and no side effects.which through inhibition of angiotensin converting enzyme?ACE?activity to decrease the blood pressure,have antihypertensive effect for high blood pressure patients.In present work,walnut meal,a by-product of walnut degreasing,as research object,Prepared of ACE inhibitory peptide after hydrolysis of protease.preliminarily separated and purification of ACE inhibitory peptides mixture.and obtained high step-down activity small molecular peptides.In this paper,walnut was used as the raw material to analyze the basic nutritional components of walnut,including protein,water,ash,fat,and reducing sugar.Compared with different extraction methods,was determined the best optimal process of extracting protein by ultrasonic assisted-alkali-acid precipitation method.After remove the skin and remove the degreasing of walnut,through the response surface test method,obtained the optimal combination parameter of extraction conditions.The results showed that the best extraction ratio of walnut protein?Y?was 55.46% under the liquid/solid was 40:1?m L/g?,Na OH concentration was 0.08%,extraction temperature was 58?and extraction time was 110 min.Enzymolyzed walnut protein with different proteases.,and the rate of hydrolysis and ACE inhibition was used as the evaluation index,the results showed that the alkaline protease had the best effect.Single factor experiment was studied by four major factors of temperature???,the substrate concentration?g/L?,enzyme amount?U/g?and p H value.Moreover,optimized the preparation technology of ACE inhibition using response surface method.The results showed that ACE inhibition ratio was 61.03% under conditions for the preparation of walnut protein were temperature 54?,the value of PH 9,the enzyme amount 7300 U/g,and the substrate concentration 2.2%.Ultrafiltration separated the hydrolysate of walnut protein by ultrafiltration for molecular intercept amount to 10 kda and 3 kda,obtained three components of less than 3 KDa,3 10 KDa,and more than 10 KDa,and the IC₅₀ value of each separation component is 0.3893mg/m L,0.9939 mg/m L and 5.9939 mg/m L,thereinto,the IC₅₀ is the lowest with molecular weight less than 3KDa.Obtained three peaks for peak 1,peak 2 and peak 3 by gel chromatography from ACE inhibitory peptide of molecular weight less than 3KDa?was obtained by ultrafiltration?.Respectively,the ACE inhibition rate of peak 2 was 80.92%,and the ACE inhibition rate of peak 1 and peak 3 were 54.28% and 68.49%,Among them,the ACE inhibition rate of peak 2was the highest,reaching 80.92%,and the peak 2 components were freeze-dried,and gained the high-activity ACE inhibitory peptide.