Preparation Of ACE Inhibitory Peptides By Proteins Extracted From Different Camellia Meal

Because the peptide inhibitor of ACE(Angiotensin-converting enzyme) of the nature food source was more saefty and no side effects advantage than the synthetic blood pressure medicine,recently,getting the peptide inhibitor of ACE from different natural food has become a hot problem in domestic and international.The camellia is by-product that virgin from camellia seed,which contains 12～15% high quality protein, camellia meal protein a kind of source with seven essential amino acids for human body growth and development..Recently, many researches demonstrated that the camellia meal protein was not only sources of nutrition but also be one of biologically active peptides. In our study,camellia meal protein were prepared from defatted camellia seeds meal through alkali extraction and acid precipitation, with ACE inhibition rate as index,using the double enzyme hydrolysis composite preparation of camellia meal peptides,further using ultrafiltration, gel chromatography for separation and purification of ACE inhibitory peptides, the Design-Expert response surface analysis method of statistical analysis software to get the optimal conditions of ultrafiltration, and the final study is as follows:This study determine the basic composition of proteins extracted from five kinds Camellia oleifera seed meal that produced in different methods. Camellia oleifera seed meal protein was obtained by alkaline extraction and acid precipitation. All their isoelectric point are different, ranging between 3.5-4.5, and the protein prepared by the Camellia oleifera seed meal after low-temperature-press, solvent extraction, enzymatic-water extraction seems to have two isoelectric points after acid precipitation. The results show that sub-acid precipitation can increase protein sedimentation rate. The alkaline extraction conditions were optimized by orthogonal experiment, and the protein extraction rate of camellia oleifera seed meal with the aqueous enzymatic extraction can reach to 66.8%.Comparing the active inhibitor of ACE of the hydrolysis product from the camellia meal protein by the Alcalase, the Neutrase,the Pepsin and the Chymotrypsin made from foreign,the optimal hydrolysis conditions were:Primary optimal protease is Alcalase,with enzyme concentration 5000 U/g,pH 8.0,temperature 50 ℃,time 3h.then adding 4000U/g Chymotrypsin to the solution for 1h.Following this optimal combi-nation to verify test results showed that the inhibitory activity of ACE inhibitory peptide reached 60.4%.In the process of the separation and purification of ACE inhibitory peptides,using the polymer molecular weight were lOkDa,5kDa,3kDa hollow fiber ultrafiltration membrane, to separation and purification of camellia meal ACE inhibitory peptides by ultrafiltration primary. Hollow fiber ultrafiltration membrane with MWCO 3kDa could effectively improve the ACE inhibitory activity of camellia meal peptides more than without ultrafiltration and the ultrafiltration components.ACE inhibition rate reached 64.2%.pH value (A), ultrafiltration temperature (B,℃), hydrolusates concentration (C,%) were purified as subject factor, The ACE inhibitory activity as response value, by the statistical analysis software Design-Expert to get the ACE inhibition rate with pH, ultrafiltration of temperature, hydrolusates concentration standard regression model.the optimal hydrolysis conditions were:Operating pressure103.42kPa, pH 6.66,temperature 31.5 ℃, hydrolusates concentration 5.5%.Under this best conditions, the ACE inhibition rate of hydrolysis polypeptide can reach 79.25% theoretically.The further separated and purificated by using Sephadex G-15 column chromatography,and got fourelution(Ⅰ, Ⅱ.,Ⅲ,Ⅳ)peak component,which was the third component has the highest ACE inhibition rate reached 85.2%.Stability of the purified fraction was studied,thermal stability, refrigeration stability and pH stability of camellia meal ACE inhibitory peptide were both well,after digestion by pepsin and trypsin simulated conditions of body digestion, ACE inhibitory activity were floating about 70.0%.It shows that camellia meal ACE inhibitory peptides can resistance to the intestinal digestive enzymes effectively.