Study On Synthesis Of Water-Soluble Dietary Fiber Polydextrose

The polydextrose was synthesized by the polymerization at vacuum. The content of reducing sugar in the product was regarded as the index of examination. This paper studied edible polycarboxylic acids, polylols, synthetic temperature, synthetic time and vacuum degree etc., as factors of impacts on the polymerization. According to the orthogonal experimental design, the optimum synthetic conditions of polydextrose was showed as following:stir speed was90r/min, vacuum degree was101kPa, synthetic temperature was170℃, synthetic time was50min, citric acid was0.7%, sorbitol was11.8%, in that condition, the content of reducing sugar was less than1%, and it was a better tasting product of lighter colour. The product was polydextrose proved by chemical method and HPLC.The effects of all factors in synthesizing process were studied. The gel chromatographic column OHpak SB-802.5and OHpak SB-804are respectively applied in analysis of molecular weight of main peak and molecular weight distribution of all products. We found that molecular weight of main peak of polydextrose is proportion to the quantity of edible polycarboxylic acids, synthetic temperature, synthetic time and vacuum degree, but in inverse proportion to the quantity of polylols; The content of high molecular polymer is proportion to synthetic time, synthetic temperature, the quantity of edible polycarboxylic acids, stirring rate and vacuum degree, but inverse to the quantity of polylols. Meanwhile it was found that the higher molecular weight of polydextrose is, the more severely dispersion degree, the products is more in homogeneity.The active carbon treatment and ultra filtration method were used for purification of polydextrose. The best decolorization workmanship was to decolor in70℃,1%quantity by30min, thus the decolored rate was74.9%and the total sugar loss rate was less than10%. In addition. Activated carbon isothermal adsorption showed that the adsorption isotherm model meet Freundlich the adsorption isotherm formula. Then the best ultra filtration conditions were at35℃,0.025MPa and the liquid density maintaining decoloring density, so the content of target product was about80%, and polymer content dropped to6.3%.Finally, the digestion resistant in vitro and the effect of polydextrose on glucose tolerance in mice were studied. The results showed that:polydextrose can’t be enzymolysised by a-amylase and glucoamylase, and can inhibit or prevent the absorption of glucose.