| Buckwheat husk is the hard shell of buckwheat seeds,which is often discarded in life and its nutritional value has not been fully exploited.According to reports,buckwheat flour polysaccharides have the functions of enhancing immunity,contributing to sleep,anti-cancer,anti-oxidation,etc.,and whether buckwheat polysaccharides have the similar functions remain to be studied.In this study,the extraction,separation,composition and antioxidant of buckwheat husk polysaccharides were analyzed and the structure and thermodynamic properties of buckwheat husk polysaccharides were explored,which can provide a reference for the study of buckwheat husk polysaccharides.The main process and results are as follows:(1)In this study,the temperature of buckwheat husk polysaccharides extraction and the suitable ethanol concentration of buckwheat husk polysaccharides were screened.Its morphology was observed by optical microscope and the UV spectrum was determined in this study.Its compositions were analyzed by HPLC.On the basis of potassium ferricyanide assay,hydroxyl radical assay,1,1-dipheny-1-2-picrylhydrazyl(DPPH)assay,the scavenging radical activities of polysaccharides from buckwheat husk were investigated.The results showed that the maximum yield of crude polysaccharides was obtained under the optimal extraction conditions as follows:extraction temperatures 80 or 90 ?(P<0.05),extraction concentrations of ethanol 95%(P<0.05).And temperature has no significant effect on the functional groups of polysaccharides.The main shapes were floc and chain.There was a strong ultraviolet absorption at 192 nm.The primary monosaccharide compositions were mannose,ribose,glucuronic acid,glucose,galactose and arabinose with a mass percentage of 6.47%,1.18%,9.66%,52.63%,17.26%,12.8%,respectively.With the increase of polysaccharide concentration,the reduction ability of potassium ferricyanide increased significantly(P<0.05),the scavenging ability of hydroxyl radicals increased,and the scavenging ability of DPPH radicals increased significantly(P<0.05).In conclusion,buckwheat husk polysaccharides were composed of six monosaccharide molecules(mannose,ribose,glucuronic acid,glucose,galactose and arabinose),they have good antioxidant activity.(2)The structures(Linking modes,functional groups,secondary structures)and thermodynamic properties of buckwheat husk polysaccharides were analyzed.The linking type of monosaccharide residues of buckwheat husk polysaccharides were analyzed by GC-MS.The functional groups of polysaccharides extracted at different temperatures were analyzed by FTIR.Circular dichroism was used to analyze the secondary structure of polysaccharide extracted at different temperatures.SDS-PAGE electrophoresis was used to analyze the effect of different temperatures on the glycation reaction and buckwheat husk polysaccharides were analyzed by DSC.The results showed that the monosaccharide residues of buckwheat husk polysaccharide mainly include 1,3-Glcp?1,6-Galb.Buckwheat husk polysaccharides belong to pyranose and the temperature has no effect on the functional group structure of buckwheat husk polysaccharides.Buckwheat husk polysaccharides extracted at different temperatures have different CD graphs.The secondary structure of the polysaccharides may be affected by the extraction temperature,but temperature has no linear relationship with the effect.With the increase of temperature,the electrophoretic bands gradually disappeared,and the glycosylation reaction occurred between the polysaccharides and proteins.DSC results showed that buckwheat peel polysaccharides may have good thermal stability between room temperature and 100 0C,while the polysaccharides above 100 ? will melt or decompose,and the stability is poor.Buckwheat husk polysaccharides belong to pyranose,the temperature does not affect its functional group structure,but temperature affects its secondary structure,protein glycosylation reaction,high temperature will also cause melting or decomposition. |
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