| Lentinus edodes is one kind of high grade nutritiousedible fungusrich in nutrients such as protein, polysaccharide, and minerals etc. Meanwhile, it has certain health care functions. To date, researches of Lentinus edodes mainly focus on Lentinus edodespolysaccharide, but Lentinus edode protein and deep procession of Lentinus edodes scraps-lentinus edodestemsare rarely studied, which leads to wastes of these precious resources. This investigation indicates that there aresignificant similarities between lentinus edode stems and lentinus edode pileus in chemical composition and therefore it is worth to develop. In view of this situation, we study the method of extraction and processing of water-soluble protein, polypeptide and dietary fiberin lentinus edode stems, which could be theory evidences for shiitake fungus industry with no waste discharges. The main contents and results are as following:1.An optimal extraction condition of water-soluble protein from lentinus edodes stems in alkalescencyis studied and the isoelectric point and molecular weight of this protein are measured as well. The result showed that the best extraction conditions of water-soluble proteinfrom lentinusedodes stems, solvent ratio, extraction time and extraction temperature,arel:28,6h and 24 ℃ respectively,and the ratio of this protein extraction is 52.8% under the above conditions. SDS-PAGE electrophoretic analysisresult indicated that the molecular weightof protein subunit bands are larger and concentrated in about 40-50ku. The isoelectric point of the water-soluble protein in lentinusedodes stems was pH4.3. close to that of most plant proteins.After extraction of water-soluble protein, dietary fiber can be gotten from the rest parts of lentinus edode stemsby twi-enzymolysis and settling in ethyl alcohol. The purity of dietary fiber is 72.4% and the yield rate is 81.2% to weight of lentinus edode stems. 2. On the research of water-soluble protein inlentinus edode stems, different kinds of polypeptides liquor are prepared by hydrolyzing water-soluble with different proteases. The polypeptide with higher lipase inhibition rate and polypeptide yield rate are investigated to optimize optimal processing conditions by single-factor and orthogonal test. Then analyzing molecular weight of the polypeptide from optimal processing condition with G50 gel chromatography. The result shows that the best proteases are thermostable alkaline protease and neutral protease X. The optimal hydrolyze conditions for hermostable alkaline proteaseare pH=8.5, T=50℃, t=60mm and neutral protease are dosage=3000U/g, pH=6.2, T=48 ℃, t=75min. The data of G50 shows that all the polypeptides molecular weight are under SKDa, among which thermostable alkaline protease polypeptide occupy 87% and neutral protease X polypeptide occupy 83%. The lipase inhibition rate of thermostable alkaline protease polypeptide and neutral protease X polypeptide are 32.4% and 27.6% dividedly. The result of this research have gotten for invention patent.3.Results of the weight reducing research on obese mice with two kinds of activepolypeptides mentioned above indicates that the serum levels of total cholesterol and glycerin trilaurate of experimental group are significant low than control group. High density lipoprotein cholesterol of experimental group are higher than control group as well. Moreover, the experimental group also have a better performance on weight gain rate, fat pad weight and fat/weight ratio. Thus, we can come to a conclusion that the effect of activepolypeptides is significant and active peptide dose and weight loss shows a dose-dependent manner. Analysis results shows that, the lentinus edode stemsactive peptide at the same time have a certain effect of lowering blood lipids. |
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