Extraction And Purification Of Water-Soluble Soybean Polysaccharides And Determination Of Their Structural Properties

Water-soluble soybean polysaccharide is called soybean polysaccharide for short,which is a kind of acidic polysaccharide,including galactose,arabinose,rhamnose,trehaloseand so on.Soybean polysaccharide has many functional properties such as dispersion,stability,emulsification and adhesiveness and can effectively improve the food quality,processing characteristics and appearance characteristics of food,which has a wideapplication prospect in food and other industries.We used bean dregs as raw material and took phosphoric acid solution to extractsoybean polysaccharide in this article.The extraction of soybean polysaccharide was studied at different solid-liquid ratios,p H,temperature,and time,and then chose the best extraction condition;Ethanol precipitation,Sevag method,dialysis,centrifugal washing and other methods were used to remove the impurities from the solution extracted.The precipitation wasisolated,purifiedand lyophilized to get the pure samples of soybean polysaccharide.Then we measured the monosaccharide composition,X-ray diffraction pattern,infrared spectrum,1H and 13 C spectra,and molecular weight of purified soybean polysaccharides;we compared the nature on surface tension,viscosity,emulsification,etc.with the soybean polysaccharide sample from Fuji Company.The main contentsand results of this paper are as follows:1.The extraction and optimized process of Soluble Soybean PolysaccharideThe basic physicochemical properties of bean dregs were measured.The characteristic method of soybean polysaccharidecontentin extracted solution,single factor experiments and orthogonal tests were carried out.The specific results are as follows:(1)The p H of bean dregsis 7.13,neutral;moisture content is 13.91%,protein contentis 16.97%,ash is 7.25%,fat is 8.07%;cellulose is 53.80%.(2)Chose the soybean polysaccharide of Fuji company as a reference product and compared the IR Spectra of Laboratory-made crude soybean polysaccharidewiththe soybean polysaccharide of Fuji Company,and then the ratio of A1041/A3417 in the IR spectrum was selected to characterize the content of soybean polysaccharide in the extracted solution.(3)The primary order to affect the soybean polysaccharide content in the extracted solution is:solid-liquid ratio> p H>extractiontime>extractiontemperature;the optimum to extract soybean polysaccharides is: solid-liquid ratio(g/m L)1:11,p H: 3.5-4.0,extraction time: 4 h,extraction temperature: 140°C.Under this condition,the crude soybean polysaccharide extraction rate is 5.42%.2.Isolation,purification and basic structure determination of purified water-soluble soybean polysaccharideSoybean polysaccharide was preliminary separated and purified.The content of polysaccharide,protein and ash about soybean polysaccharide before and after purification were compared.We determined the basic structure of purified soybean polysaccharide which included monosaccharide composition,X-ray diffraction pattern,infrared spectrum,NMR and molecular weight.The specific results are as follows:(1)Crude soybean polysaccharide contains 56.32% polysaccharide,3.24% protein and 5.64% ash.The polysaccharide content in the purified soybean polysaccharide is 72.25%,protein is 2.46%,and ash is 3.25%.(2)The monosaccharide composition of purified soybean polysaccharide contains galactose,rhamnose and arabinose,and the corresponding molar ratio is 1:0.6:0.4;X-ray diffraction pattern results show that the soybean polysaccharide sample is amorphous;according to the 1H and 13 C NMR Spectra of Soybean Polysaccharide Samples,it can be preliminarily concluded that ?-furanose is a polysaccharide in soybean polysaccharides.It is speculated that there may be 6 sugar residues in the sample of soybean polysaccharide,and the anomeric carbon of sugar residue has both ?-configuration and ?-configuration;The GPC results show that the molar ratio of purified polysaccharides with different molecular weightis 498KDa:24.8KDa: 4.98KDa=62.5:6.25:31.25,and the average molecular weight of soybean polysaccharide is about 314.36 KDa.3.Determination of physical and chemical properties of Soluble Soybean PolysaccharideWe analyzed and measured the basic physical and chemical properties of homemade soybean polysaccharide and soybean polysaccharide sample of Fuji Company.The microscopic appearance of both polysaccharides was analyzed.We measured the changes of viscositywith temperatureon the two polysaccharide samples,the surface tension at different concentrations as well as the emulsifying properties.The specific results are as follows:(1)Both soybean polysaccharide samples are water soluble at room temperature;The moisture content of homemade soybean polysaccharide samples is 10.21%;ash content is 5.25%;protein content is 3.14%;p H is 5.42,acidic;conductivity is 2.65 m S·cm-1.The water content of soybean polysaccharide from Fuji Companyis 10.92%;ash is 6.72%;protein is 4.82%;p H is 5.50;conductivity is 3.37 m S·cm-1.It can be concluded that both of the soybean polysaccharide samples have similar moisture content and the solutions are all acidic.(2)HPLC sugar component result display that both soybean polysaccharide samples are mainly composed of tetrasaccharides and above,and the proportion of tetrasaccharides in the sample of Fuji Companyis more than that of self-made soybeanpolysaccharide;SEM results show that the homemade soybean polysaccharide sample is in the shape of a splinter,whilethe sample of Fuji Companyis spherical;The viscosity of two polysaccharide samplesis quite different at the same concentration and temperature;The surface tension of the two soybean polysaccharide samples decreases with the increase of mass fraction;the emulsifying performance of the homemade soybean polysaccharide samples is lower than thesample of Fuji Company.