Purification And Separation Of Yanshan Chestnut Polysaccharide By Membrane Separation/Three-Phase Partitioning And Its Structural Characterization And Biological Activity

At present,the unique pharmacological effects and health care values of chestnut have not been fully explored,and relatively little research has been conducted on the nutritional and functional components contained in chestnut,especially on chestnut polysaccharides,which are still at the initial stage.In this thesis,the crude polysaccharides of chestnut seed kernels were extracted from four different varieties of Yanshan chestnut by hot water extraction,and the extraction process conditions of crude polysaccharides were optimized with the help of response surface methodology.The physicochemical properties of the semi-purified polysaccharides and neutral polysaccharides were tested,and the monosaccharide composition and structure of different varieties of neutral polysaccharides were analyzed,and the differences in the physicochemical properties and structural composition of different varieties of chestnut polysaccharides were comparatively characterized.On this basis,the antioxidant activity as well as hypoglycemic activity of different varieties of chestnut polysaccharides were analyzed and studied,and the main conclusions were as follows:1.The optimal process conditions for the extraction of chestnut polysaccharides by hot water extraction method were obtained by single-factor experiments combined with response surface optimization:the highest extraction rate could reach 13.06%±0.25%at the extraction temperature of 80℃,time of 2 h and liquid to material ratio of15:1 m L/g.2.Both the MS and TPP methods could significantly increase the sugar content and decrease the protein and glyoxylate content of the samples,and the TPP method had a higher purification yield and the MS method had a better purification effect.FTIR,SEM,TG and XRD analysis showed that the obtained semi-purified polysaccharides all had typical polysaccharide characteristic absorption;the particle morphology of M series semi-purified polysaccharides varied significantly depending on the species,and T series semi-purified polysaccharides were all flaky and microscopic.The particle morphology of M series semi-purified polysaccharides differed significantly from species to species,while T series semi-purified polysaccharides were all flaky microscopic particles with different pore sizes and distributions on the surface;T series semi-purified polysaccharides had relatively high thermal stability;M series and T series semi-purified polysaccharides showed amorphous states.3.The column chromatography purification could further increase the sugar content to more than 80%,and the purified polysaccharide was almost free of glyoxalate,and neutral polysaccharide was obtained.the physicochemical properties of M series and T series neutral polysaccharides showed some differences,and the physicochemical properties of different varieties of neutral polysaccharides also had some differences.4.The neutral polysaccharides obtained consisted of five monosaccharides,Ara,Gal,Glc,Xyl and Man.The monosaccharide composition of each neutral polysaccharide was different,but they were all branched polysaccharides,and the branched points were mainly located on Gal,Glc and Man.The molecular weight of the same species polysaccharide,M series is higher than T series,and the molecular weight distribution of T series is narrower than M series.The bonding structures of neutral polysaccharides also differed greatly depending on the purification method and the chestnut species.5.Both the obtained semi-purified polysaccharides and neutral polysaccharides showed some antioxidant activity,and the antioxidant activity of the semi-purified polysaccharides was stronger than that of the neutral polysaccharides in general.The inhibitory activity of the semi-purified polysaccharides onα-amylase was significantly stronger than that of the neutral polysaccharides.Four chestnut polysaccharides with excellent hypoglycemic activity,YXP（M）,YFP（M）,YFP（T）and YXP（T）,were screened,and the IC₅₀ values of the half-inhibitory concentration onα-amylase were1.21,1.14,0.92 and 1.22 mg/m L,respectively.