Study On Preparing Ace Inhibitory Peptides From Buffalo Milk Protein With Enzymatic Hydrolysis

High blood pressure is one of important risk factors of cardiovascular disease, but which also is the main controllable risk factors. Angiotensin1-converting enzyme is the main factors to adjust blood pressure, and the blood pressure will be lower when the ACE activity was restrained. In this dissertation, the ACE inhibitory peptides were producted from buffalo milk. Furthermore, the gastrointestinal simulation experiment and the thermal stability and acid-base stability of ACE inhibitory peptides were investigated.Buffalo milk was hydrolyzed by six different proteolytic enzymes, finally the pepsin was screened for the best enzyme for producing ACE inhibitory peptides. Further on, the hydrolysis time, enzyme concentrations, substrate concentrations, hydrolysis temperatures and pH values were investigated. The result of optimal conditions for producing ACE inhibitory peptides were as follows:enzyme concentrations in8000U·g-1, substrate concentrations in1.5%, hydrolysis temperature at37℃, pH2.0and hydrolysis time in3h. Under this condition, the inhibition percent of ACE of hydrolysate was60.7%, hydrolysis degree was15.8%.The stability of the ACE inhibitory peptides were produced in the gastrointestinal digestive enzymes, and the effects of temperature and pH on ACE inhibitory activity were investigated. The results indicated that the ACE inhibitory peptides had a good resistance to the influence of pepsin; when the pH was3-8, the ACE inhibitory peptides producted from buffalo milk showed a good acid-base stability; when the temperature below60℃, the ACE inhibitory peptides showed a good thermal stability.Finally, the ultrafiltration technology was used to separate and enrich the active parts of hydrolysates. Result showed that the peptides of molecular weight more than10KDa were basic intercepted, and the content of ones that molecular weight lower than5KDa were increased to88.6%in the third components; The inhibition percent of ACE of belong to5-10KDa and lower5KDa components were in tune improved after ultrafiltration, finally, the inhibition percent of ACE of lower5KDa components reached87.7%and were1.45times than hydrolysates inhibition percent of ACE.