Structural Identification Of Hericium Erinaceus β-glucan And Its Interaction With Starch

With the increase in the number of chronic patients such as diabetes and obesity,people not only pay attention to the green and health of food,but also pay more attention to the health effects of food function factors on the human body.The seed body of Hericium erinaceus was used as raw material,and Hericium erinaceusβ-Glucan(HEBG)was extracted by water extraction and alcohol precipitation.The structure and solution conformation were characterized by various characterization methods.Then,using different treatment methods for HEBG,in vitro digestion experiments were carried out to explore the mechanism of inhibiting starch digestion,and provided a theoretical reference for the application of edible fungusβ-glucan to foods and cosmetics.The main findings were as follows:1.The HEBG extracted from the fruiting body of Hericium erinaceus was determined to have a purity of 79.21%;the molecular weight was determined by high performance liquid phase method,and the results showed that the weight average molecular weight was 7.504×10~5 Da;gas chromatography,infrared spectroscopy,periodate oxidation,Smith degradation,methylation analysis and nuclear magnetic resonance spectroscopy analysis of the primary structure of HEBG,the results showed that HEBG was a homogeneous polysaccharide composed ofβ-D-glucose(Glu),its main chain was 1,3-Glu.The HEBG branch is composed of a 1,6-Glu residue,and the molar ratio of 1,3-Glu to 1,6-Glu is 1:1.2.The intrinsic viscosity of HEBG in aqueous solution was 3.02 dL/g,the Huggins constant K’was 1.54,and the red shift phenomenon was observed by the intrinsic viscosity test and Congo red experiment,indicating that there were not only random lines in the diluted solution of HEBG.The structure of the cluster also has a triple helix structure;the empirical constantαof the Mark-Houwink-Sakurada equation of HEBG measured by size exclusion chromatography and multi-angle laser scatterer system is0.759,which also indicates that HEBG is randomly coiled in water.Structure and the microstructure of HEBG were observed by scanning electron microscopy and atomic force microscopy.The molecular chain diameter was 0.55±0.11 nm and the width was 1.9nm.And the random coil structure of the polysaccharide and the branched structure of the molecular chain were clearly observed.3.Three different HEBGs(HEBG-1,HEBG-2,HEBG-3)were processed bysodium hydroxide,β-1,3 glucanase andβ-1,6 glucanase,respectively.The molecular weights were7.30×10~5 Da,4.105×10~5 Da and 4.573×10~5 Da,respectively.The Congo red assay showed that there were no triple helix structures in the three polysaccharides;Determined by periodate oxidation,Smith degradation and methylation experiments.The structure of HEBG-2 and HEBG-3 indicates that the main composition of HEBG-2 wasβ-1,6-glucan,and the main composition of HEBG-3 wasβ-1,3-glucan.4.The effects of four kinds of dextran on the in vitro digestion of wheat starch were investigated by Englyst method.The results showed that HEBG could significantly reduce the digestibility of starch,and the larger the molecular weight,the better the inhibition effect;and the triple helix structure in HEBG played an important role in inhibiting starch digestion,in which starch digestion was inhibited as the triple helix structure was destroyed.HEBG treated with enzyme also had different effects in inhibiting starch digestion,HEBG-3 composed ofβ-1,3 glucan had a stronger inhibitory effect,indicating that theβ-1,3 glycosidic bond contributed more to the inhibition of starch digestion than theβ-1,6 glycosidic bond in HEBG.