Study On Preparation,physicochemical Properties And Antioxidant Activity Of Pleurotus Eryngii Isolated Protein

Pleurotus eryngii is a kind of mushroom which has been successfully developed and cultivated in recent years.The protein content of dry matter in Pleurotus eryngii is about 12.4%-35%.It has many pharmacological effects.It is a high-quality protein source of mushroom.In this paper,the preparation method,protein structure,function,nutritional characteristics and antioxidant activity of Pleurotus eryngii isolated protein were studied,which provided theoretical basis and technical basis for the development of Pleurotus eryngii protein isolated protein.The main conclusions of this paper are as follows:(1)Alkali extraction method was used to extract Pleurotus eryngii isolated protein.After optimization by response surface methodology,The best conditions were as follows:extraction pH was 10.00,extraction time was 4.1 h,extraction temperature was 41 ?.Under this condition,the recovery rate(67.09±0.26)%.,the purity was(73.25±0.17)%.Under the optimum conditions of alkaline extraction,the Pleurotus eryngii isolated proteins were separated by ultrafiltration membranes with different interception molecular weights,and three components with different molecular weights of>100 kDa,50-100 kDa and 10-50 kDa were obtained.>100 kDa protein component recovery rate was(22.16±1.54)%,purity was(64.87±3.05)%.The recovery rates of 10-50 kDa protein fraction was(8.35±0.57)%,purity was(80.23±1.36)%· And 10-50 kDa protein fraction recovery rate was(13.73±0.19)%,purity was(79.85±0.51)%.,the purity of 50-100 kDa and 10-50 kDa protein fraction were higher than the Pleurotus eryngii isolated protein prepared by alkali method.(2)Mino acid content and ratio of essential amino acid to non-essential amino acid of 50-100 kDa and 10-50 kDa protein components were better than those of other two proteins.Solubility,water holding capacity and emulsifying stability of 50-100 kDa and 10-50 kDa protein components were better than those of other two proteins.50-100 kDa and 10-50 kDa protein components Fluorescence spectra showed that they were located in a more hydrophilic environment than those of Pleurotus eryngii isolate(alkaline method).Scanning electron microscopy showed 50-100 kDa and 10-50 kDa protein components were looser than other proteins.50-100 kDa and 10-50 kDa protein components electrophoretic bands showed seven d:istinct protein subunits with molecular weights of 145 kDa,94 kDa,52 kDa,40 kDa,37 kDa,35 kDa and 17 kDa.The content of disulfide bond,total sulfhydryl group,thermal denaturation temperature and surface hydrophobicity of 100 kDa protein components were the highest,which were(197.79±1.32)?mol/g protein,(93.77±0.63)?mol/g protein,81.9 ?,(103.41±7.42),respectively.(3)The scavenging capacity of DPPH free radicals,reduction ability,Fe2+ chelating force and superoxide anion free radicals of 10-50 kDa protein fraction were better than other proteins,and the scavenging capacity of hydroxyl radicals(·OH)of 50-100 kDa protein fraction was higher than that of other proteins.Combining the results of five antioxidant activities,antioxidant activity of Pleurotus eryngii isolated protein has a concentration-dependent effect,it can be seen that the 10-50 kDa and 50-100 kDa protein components extracted by membrane method have stronger antioxidant activity than those extracted by alkali method.