Research Of The New Preparation Conditions Of Walnut Polypeptides By Enzymatic Hydrolysis

Walnut proteins was recognized as quality protein resources, but people were always ignore this resource, most of the walnut slag were directly discarded, caused the waste of resources. With walnut protein as raw material to develop good high value-added walnut active peptide products, It is very significant for the healthy development of walnut production. The traditional production method of walnut polypeptides were hydrolyze with free enzyme under the conditions of water heating, the shortcoming was that time was too long, enzyme could not be recovered effectively. So high efficient methods to break down protein into polypeptides were researched.Immobilized enzyme was used to hydrolyze walnut pritein. Chitosan is a kind of high-quality immobilized enzyme materials, so microspheres were prepared from chitosan and applied to the immobilization of papain.The optimum pH of immobilized papain was8.0and that of free papain was9.0, The optimum temperature had no change, both were60℃. Compared with free papain, the thermal stability, the pH stability and storage stability all were improved. The optimal conditions of hydrolysis were as follows:solid-liquid than1:20, time8h, add enzyme quantity1.8g/g the substrate. Immobilized enzyme can reduce the production cost, on the other hand, don’t add any impurity to protein hydrolysate basically, if immobilized enzyme activity could be improved again, it will have a good application prospect.Study the feasibility and result of microwave heating to replace the traditional water heating, found that:microwave heating shortened reaction time and increased decomposition efficiency. Under the micorwave haeting a few minutes, we got the hydorlysis degree that need several hours in normal enzyme hydrolysis. Study the optimum hydrolyzing conditions of papain and neutral protease by the single factor experiment and the orthogonal experiment, the results was as follows:The optimal enzymatic hydrolysis of papain was that substrate concentration is4%, pH7.0, enzyme-substrate than for the6000U/g, time was7min; The optimal enzymatic hydrolysis of neutral protease was that substrate concentration is5%, pH9.0, enzyme-substrate than for the6000U/g, time was6min. The study also found that under the same condition, the hydrolysis of neutral protease was better than papain.At last, the relative molecular weight distributionof walnut polypeptides of neutral protease by micorwave haeting were determined and analyzed by high gel permeation chromatography and hollow fiber membrane filter. Experimental results indicated that the realative molecular weight of the most of walnut polypeptides was below3000, the polypeptides were predominated (60%)...