Fractional Precipitation Behavior,Modification Of Carboxymethylated Gleditsia Sinensis Gums

The Gleditsia sinensis is a leguminous plant,which is one of the most widely distributed species in China,and has excellent ecological,economic and social properties.It is a rare multifunctional eco-economic tree species with the potential of exploiting and utilizing the green industry raw material resources.However,the molecular weight and the water solubility of Gleditsia sinensis gum(GSG)are not suitable for the industrial utilization.Thereby,purification and structural modification of galactomannan polysaccharides is one of the hottest topics in recent research.In this paper,we purified Gleditsia sinensis gum(GSG)by using different concentrations of ethanol,and the preparation of carboxymethylated GSG and its corresponding antioxidant activity were studied.The experiment provided scientific basis for the next relating research and development of the functional food,medicine and materials.The main research contents and results are as follows:(1)The fractionation and purification of the crude galactomannan polysaccharide by the alcohol precipitation operation can improve the quality of the galactomannan polysaccharide in the manufacture of multifunctional materials.During purification,the concentration of ethanol solvent can be modified according to the molecular weight of galactomannan,and the total yield could achieve more than 80%.After the precipitation of galactomannan,three purified fractionations were obtained,and the molecular weight and the proportion of monosaccharide components of the polysaccharide gel of each conponent were characterized by high performance liquid chromatography and gel chromatography,and the rheological property was analyzed by rheometer.(2)"Solvent method" to prepare carboxymethylated polysaccharide(CMGSG):Using NaOH and DMAC in isopropanol solution system is an easy method to get carboxymethylated polysaccharide.The yield of carboxymethyl modification is 63.05%.The structure of CMGSG was characterized by IR and NMR.(3)The scavenging effect of CMGSG on DPPH,ABTS and OH radicals was used to characterize the oxidation of CMGSG.