Extraction,Separation Purification And Biological Activity Analysis Of Fermented Wheat Bran Polysaccharide

Microbial fermentation improved the nutrient composition and increased the yield of of wheat bran polysaccharide.The production technology and biological activity of fermented wheat bran crude polysaccharide were studied in the laboratory.on this basis,the extraction process of fermented wheat bran polysaccharide was further optimized.Four homogeneous heteropolysaccharides were isolated and purified by column chromatography,and their structure and biological activities were studied.The thesis mainly includes the following four parts:1.Response surface method was used to optimize the extraction process of fermented wheat bran polysaccharideFirstly,the effects of different extraction conditions on FWBP content were studied by setting different water bath extraction temperature,water bath extraction time and solid-liquid ratio by single factor method.The results showed that the optimum extraction conditions were water bath extraction temperature 90?,water bath extraction time 30 min,solid-liquid ratio 1:20,FWBP content was the highest.Based on the above single factor experiment results,three factors and three levels of response surface optimization analysis were carried out by selecting water bath extraction time(A),water bath extraction temperature(B),material-liquid ratio(C)as independent variables and fermented wheat bran polysaccharide content(Y)as response value.the results showed that the average content of polysaccharide was 296.98 mg/g when the extraction temperature was 90?,the extraction time was 60 min and the ratio of material to liquid was 1:22.The theoretical predicted value of polysaccharide content obtained by regression equation was 293.11 mg/g.There was no significant difference between the actual value and the theoretical value.2 Analysis of active components of fermented wheat bran crude polysaccharideThe contents of polysaccharides,proteins,polyphenols,glucuronic acid and monosaccharides in the wheat bran crude polysaccharide(WBP)before and after fermentation were determined.The results showed that the protein,polyphenol and glucuronic acid contents of FWBP were higher than those of WBP(P<0.05),and the polysaccharide yield of FWBP was higher than that of WBP.WBP and FWBP have the same monosaccharide composition,including mannose(Man),rhamnose(Rha),glucose(Glc),galactose(Gal),xylose(Xyl)s arabinose(Arabosine).However,the molar ratio of WBP to FWBP was 3:1:45:17:80:46,while that of FWBP was 5:4:46:9:67:46.The xylose content decreased significantly.The results showed that fermentation had a significant effect on the chemical composition of polysaccharides.3 Isolation,Purification and Structural Analysis of fermented Bran Polysaccharide3.1 Separation and Purification of Fermented Wheat wheat bran polysaccharideThe crude polysaccharides from fermented wheat bran were purified by DEAE-52 cellulose column,and the polysaccharides and proteins of the purified part were determined.Two components were eluted by DEAE-52 cellulose column,namely FWBP-1 eluted by distilled water and FWBP-2 eluted by 0.1 mol/L NaCl.The polysaccharides contents of FWBP-1 and FWBP-2 were 955.25 and 634.32 mg/g,respectively.The protein contents of FWBP-1 and FWBP-2 were 134.92 and 260.20 mg/g,respectively.Four components were separated by dextr SephadexG-100 column,namely FWBP-11,FWBP-12,FWBP-21 and FWBP-22.3.2 Structural Composition Analysis of fermented wheat bran polysaccharideAfter purification by DEAE-52 cellulose column,the physical and chemical components of FWBP-1 and FWBP-2 were determined,ultraviolet analysis and scanning electron microscopy were observed,and the monosaccharide composition,molecular weight and infrared structure of FWBP-11,FWBP-12,FWBP-21 and FWBP-22 were determined.The results showed that two kinds of polysaccharides FWBP-1 and FWBP-2 had weak absorption peaks at wavelengths of 280 nm,and two components contained some proteins.Under different times,FWBP-1 showed thick rod like shape,FWBP-2 was thinner flake,FWBP-1 surface was smooth,and FWBP-2 surface was slightly rough;four components separated by Sephadex G-100 column,namely FWBP-11,FWBP-12 and FWBP-21 FWBP-22.Mannose,rhamnose,glucose,galactose,xylose,arabinose and fucose were found in FWBP-11,FWBP-12 and FWBP-21,FWBP-22.which contained a large proportion of xylose and arabinose.The average molecular weights of the four components were 40.58,5.92,37.65 and 7.43 kDa,respectively.Infrared structure showed that the four components had different intensity of arabinose-xylan and protein peak vibration.4 Study on the biological activity of fermented bran polysaccharideThe effects of WBP,FWBP,FWBP-1 and FWBP-2 on scavenging of DPPH and hydroxyl radicals and reducing ability were studied.The probiotics activities of WBP and FWBP on Lactobacillus plantarum,Bifidobacterium and Lactobacillus acidophilus were compared.The results showed that FWBP had significantly higher DPPH free radical scavenging rate and reducing power than WBP,and lower hydroxyl radical scavenging rate than WBP(P<0.05);FWBP-2 had higher reducing power and free radical scavenging rate than FWBP-1(P<0.05);WBP and FWBP have probiotic effects on Lactobacillus plantarum,Bifidobacterium and Lactobacillus acidophilus,and their probiotic effects on Bifidobacterium bifidum are significantly higher than those of the other two probiotics(P<0.05).When the concentration of polysaccharide was 2 mg/ml,the probiotic effect was the strongest,and FWBP was significantly higher than WBP.