Chemical Modification And Functional Properties Of Soybean Polysaccharides

Soybean polysaccharides(SSPS)are a kind of water-soluble acidic polysaccharide,which have many functional properties,such as inhibiting lipid oxidation,reducing cholesterol and blood glucose,etc.At present,many researches focus on soybean polysaccharides and their properties,but the researches on chemical modification of soybean polysaccharides are very fewer,which limits their further application.In order to broaden the application of soybean polysaccharides in food industry,the structure and functional properties of oxidative soybean polysaccharides were first discussed.In addition,aspartic acid and glutamic acid are two common amino acids in soybean,which are easy to react with soybean polysaccharides during food processing.The structure and functional properties of soybean polysaccharides in two model Maillard reaction systems were also discussed in this study.The main conclusions are as follows:1.Two oxidation products(OSSPS-1 and OSSPS-2)were prepared by controlling the content of sodium hypochlorite.Structural analysis showed that the hydroxyl groups of SSPS were oxidized to carboxyl groups.The molecular weight of SSPS decreased slightly after oxidative modification,but carboxyl content and uronic acid content increased.The emulsifying property and protein dispersion stability of SSPS were decreased after oxidative modification.Oxidative modification greatly reduced the viscosity of SSPS and changed their viscoelasticity.Oxidative modification improved a series of viscosity-related functional properties of SSPS,such as fat binding capacity,bile acid binding capacity,hypoglycemic effect.The antioxidant and antibacterial activities of SSPS were enhanced after oxidation modification.The antioxidant activities of OSSPS-1 were better than those of OSSPS-2,whereas OSSPS-2 exhibited better antibacterial activities than OSSPS-1.2.In model Maillard reaction system of SSPS and aspartic acid,the absorbance increased with the increasing of reaction time,but the fluorescence intensity showed the increasing and then decreasing trend.Structural analysis showed that the carbonyl groups of soybean polysaccharides interacted with the amino groups of aspartic acid to form macromolecules.The molecular weight and uronic acid content of the Maillard conjugates of SSPS were increased.Compared with SSPS,the emulsifying property of the Maillard conjugates were improved,but the protein dispersion stability decreased remarkably.The viscosity of SSPS was decreased by Maillard reaction,but Maillard reaction improved a series of viscosity-related functional properties of SSPS,such as fat binding ability,bile acid binding ability,hypoglycemic effect.Compared with SSPS,the antioxidant activities of Maillard conjugates were enhanced,which might be related to the increase of uronic acid content.In addition,Maillard reaction enhanced the antibacterial activities of SSPS.3.In model Maillard reaction system of SSPS and glutamic acid,the absorbance increased with the increase of reaction time,but the fluorescence intensity showed the increasing and then decreasing trend.Structural analysis showed that the carbonyl groups of soybean polysaccharides interacted with the amino groups of glutamic acid to form macromolecules.The molecular weight and uronic acid content of the Maillard conjugates of SSPS were increased.Maillard reaction improved the emulsifying property of the Maillard conjugates(mass ratio 1:1),but the emulsifying property of the Maillard conjugates(mass ratio 2:1 and 5:1)decreased.After Maillard reaction,the protein dispersion stability and viscosity of SSPS decreased,and their viscoelasticity did not change.Maillard reaction enhanced a series of viscosity-related functional properties of SSPS,such as fat binding ability,bile acid binding ability,hypoglycemic effect.Compared with SSPS,the antioxidant activities and antibacterial activities of the Maillard conjugates were enhanced.In this study,oxidative modification and Maillard reaction were used as modification methods of SSPS.The effects of oxidative modification and Maillard reaction on the structure,physicochemical properties,physiological and biological activities of SSPS were investigate,and the potential structure-activity relationship of SSPS was preliminarily analyzed.This provides a new idea for expanding the application of soybean polysaccharides in food.