Preparation Of Walnut Meal Lipid-lowering Peptide And Study On Its Lowering Blood-lipid Effect

Hyperlipidemia is a chronic syndrome caused by dyslipidemia,which seriously threatens human health.In recent years,many studies have shown that many food proteins can not only provide essential amino acids,but also provide bioactive polypeptides.As a natural active substance that can effectively improve blood lipid balance in the body,hypolipidemic active peptides have attracted the attention of many scholars.Walnut meal,as a by-product of cold-squeezed walnut kernel oil,is rich in nutrition and high in protein.It has been reported that walnut peptide has the function of reducing blood lipid,but there are few reports on the production of hypolipidemic peptides by enzymatic hydrolysis of walnut meal proteins.In this paper,walnut meal after cold pressing was used as raw material to prepare hypolipidemic peptides from walnut meal by enzymolysis method,and the effect of the hypolipidemic peptides of walnut meal on lipid metabolism in hyperlipidemic rats was investigated.The results of the study were as follows:1.The six proteases,alkaline protease,neutral protease,papain,trypsin,pepsin,and Alcalase 2.4 L were filtered by using the two in vitro cholesterol inhibition experiments of pancreatic lipase inhibition rate and cholesterol micellar solubility inhibition rate as indicators.The results showed that Alcalase 2.4 L had a good comprehensive effect,and the best enzyme for enzymatic hydrolysis of walnut meal was Alcalase2.4 L.2.The conditions of Alcalase 2.4 L enzymatic hydrolysis were optimized,the degree of hydrolysis was used as an indicator,and the single factor test and response surface Box-Behnken central combination test design showed that the optimal enzymatic hydrolysis conditions for the preparation of walnut meal hypolipidemic peptides are:substrate concentration 4.2%,enzyme amount 7.0%,pH 8.0,time 4.5 h.Under these conditions,the hydrolysis rate of walnut peptides can reach 18.94%.3.The hydrolysate was separated into WPH-I,WPH-II,and WPH-III using 10 KDa and 3 KDa ultrafiltration membranes.The inhibition rate of pancreatic lipase activity and the inhibition rate of cholesterol micelle solubility were used to evaluate the reduction of blood lipids.For activity,select WPH-I components to separate and purify.The WPH-I components were separated by Sephadex G-25 by a dextran gel column,and the inhibition rate of pancreatic lipase activity was measured.It was found that the P1 group had higher activity.LC-MS/MS was performed on the component P1,and a total of 194 peptides from 10 proteins were obtained.4.Establish a rat high-fat model,and intervene high-fat rats with three doses of walnut meal hypolipidemic peptides.The results show that walnut meal hypolipidemic peptides can significantly alleviate the increase in rat body weight,liver and fat weight.It also can reduce rat serum TG,TC,LDL-C content,increase HDL-C content,reduce liver TC,TG content and atherosclerosis index at the same time.By measuring rat apolipoprotein Apo-A1,Apo-B and lipid metabolism-related enzymes FAS,HMGR,CYP7A1,LCAT,it was found that the walnut meal hypolipidemic peptides can regulate the apolipoprotein level,increase the activity of LCAT and CYP7A1,and inhibit FAS and HMGR activity.After measuring the activity of AST and ALT in the serum,making liver tissue slices,we can find that walnut meal hypolipidemic peptides can reduce the accumulation of fat in the liver and slow down liver damage.By making cecal tissue slices,the results show that walnut meal hypolipidemic peptides can increase the cecal villi,thicken the cecal wall,and protect the intestinal tract.