Study On Extraction And Biological Activity Of Protein From Dictyophora Echinovolvata Pileus

In this study, proteins were extracted from Dictyophora echinovolvata pileus, and then its nutrient components, optimization of extraction parameters and its antioxidant activity were determined. Main results were as follows:(1) The contents of nutritional components and amino acids of Dictyophora echinovolvata pileus were detected using national standards analytic methods. The results showed that, compared with Flammulina, Pholiota nameko and Pleurotus eryngii, the total content of essential amino acids in Dictyophora echinovolvata pileus was the highest, which occupies 41.32% of total amino acids. Moreover, its amino acid score (AAS), chemical score (CS), essential amino acid index (EAAI), biological value (BV), nutritional index (NI), score of ratio coefficient of amino acid(SRCAA) of protein were 65.71,54.24,76.58,71.77,29.05 and 73.18, respectively, which were higher than those of Flammulina, Pholiota nameko and Pleurotus eryngii. The results indicated that Dictyophora echinovolvata pileus is a suitable raw material for extracting proteins with high nutritive value.(2) Study on extraction and analysis of protein from Dictyophora echinovolvata pileus. Based on their solubilities in water,5% NaCl,0.1 M NaOH and 70% ethanol, proteins were extracted from Dictyophora echinovolvata pileus according to Osborne method (OSB). These extracts were then compared to the fraction obtained by direct alkaline extraction method (DIR) in terms of protein yield. The cumulative protein yield with OSB was higher than with DIR, but after considering cost and protein yield of the method, DIR was more suitable for this experiment. The optimal protein extraction process was studied by single factor and orthogonal experiment. The molecular weight distribution of extracted protein was analyzed by SDS-PAGE. The results indicated that pH and extraction time were the most important factors in the extraction process. The highest extraction yield of up to 57.07% was obtained at pH 8.5,55℃, and 2.5 h of extraction. And the major bands of MW of extracted protein were 16 kDa and 38 kDa.(3) Study on enzymatic hydrolysis of Dictyophora echinovolvata pileus. Proteins in Dictyophora echinovolvata pileus were hydrolyzed by papain and pepsin. Proteinase activity in Dictyophora echinovolvata pileus was higher with papain. The optimal reaction conditions for papain were studied by single factor and orthogonal experiment. The molecular weight distribution of extracted protein was analyzed by Tricine-SDS-PAGE. It indicated that pH and extraction temperature were the most important factors in the extraction process. The highest extraction yield of up to 64.05% was obtained at pH 7.5,45℃, concentration of enzyme 1.50% (E/S), and 4 h of extraction. The molecular weight distribution of extracted protein varied from 5.8 to 30 kDa. And the major bands of MW of extracted protein were 18 kDa.(4) Studies on the optimization of drying method and antioxidant activity of protein in Dictyophora echinovolvata pileus. The effect of drying methods (spray drying and vacuum freeze-drying) on the antioxidant activity of protein extracting solution obtained from Dictyophora echinovolvata pileus was studied. The results indicated that freeze-dried protein powder from enzymatic hydrolyzate having the best antioxidant activity. It possesses marked reducing capacity, and remarkable DPPH and hydroxyl radical scavenging activity in vitro.