Study On The Preparation And Activity Of Hypocholesterolemic Peptide From Walnut

With the improvement of people's living standards and their emphasis on health,peptides,as a proteolytic intermediate,have a higher absorption rate in the human body than amino acids,and have a variety of biological activities such as reducing cholesterol and blood lipids.A health product with high safety and no toxic side effects.Walnut protein is mainly composed of gluten,gliadin,and globulin.The gluten content is about 70%.Therefore,the solubility of walnut protein is very poor,but the solubility of walnut protein is greatly increased after it is made into a polypeptide.In this experiment,the extraction process of walnut protein was optimized on the basis of alkaline extraction and acid precipitation,and cholesterol-lowering walnut peptide was obtained by alkaline protease hydrolysis.And a preliminary separation of cholesterol-lowering walnut peptides yielded small molecules with strong activity.So it provides a new direction for the processing and development of walnut protein resources.1.Firstly,the content of oil,protein,water and ash in walnut kernel was measured.The protein content of defatted walnut protein powder was 62.41%.The optimal extraction technology of walnut protein was obtained by orthogonal experiment.The ratio of defatted walnut powder to deionized water was 1:30mg /ml,time was 90 min,temperature was 60 ?,p H was 11,the protein extraction rate was 53.23%.2.The alkaline protease was determined to be the hydrolytic enzyme of cholesterol lowering walnut polypeptide by the index of cholesterol inhibition rate and hydrolysis degree,and the influence of substrate concentration,temperature,p H value and enzyme amount on the activity of cholesterol lowering walnut polypeptide was studied by the index of cholesterol inhibiting ability of cholesterol micelle in vitro.The temperature was 55?,p H value was 9.0 by response surface analysis was 7300 u /g,the substrate concentration was 2.5%,and the inhibition rate of cholesterol was 60.17%.3.The walnut polypeptide was separated and purified by ultrafiltration tube.The results showed that the inhibition rate of walnut polypeptide with molecular weight of 50-10 k Da was the lowest.The inhibition rate of walnut polypeptide with molecular weight of 50-10 k Da to cholesterol was 54.81%.The inhibition rate of walnut polypeptide with molecular weight of less than 10 k Da to cholesterol micelle,cholic acid salt,deoxycholic acid salt and taurocholate was 76.49%,58.70%,73.61% and 48.43%.4.Through the simulation digestion experiment in vitro,it was found that the cholesterol inhibition rate of the peptide was decreased due to the gastrointestinal digestion after the simulation stomach digestion and the simulation intestine digestion,but it still had biological activity.The results showed that the solubility of walnut polypeptide before and after enzymatic hydrolysis was significantly higher than that of walnut protein.After enzymatic hydrolysis,the structure of polypeptide was more loose,and its oil absorption and emulsification were also improved,because the viscosity decreased,the surface tension decreased,and the foaming property of polypeptide was enhanced,but the foaming stability changed little.After enzymatic hydrolysis,the protein binding changed,and the water holding capacity of walnut polypeptide was lower than that of walnut protein.