Influence of decolorization and drying methods on the quality of pullulan polysaccharides

The decoloration and the influence of drying methods on the quality of pullulan polysaccharides were mainly studied. First, the type of ZY-24×48-B was selected from four types of activated carbon. Based on the single factor result, orthogonal experiment was performed to select the best condition for decoloration of pullulan. The best technological process of decoloration was adding 1.0% (w/v) activated carbon to pullulan solution at 40℃, with pH at 5.0 and decoloring the solution for 40min. The decolorization rate was 94.98%, pullulan polysaccharide yield was 91.24%. Then the suitable drying methods of pullulan polysaccharides for industrialized production was determined which was depended on the effect of microwave drying, spray drying and vacuum freeze drying on the quality of the purity of pullulan polysaccharides, tmicroscopic characterization, solubility and colour. The test indicated that the colour of spray dried product were better than that of microwave dried (L=89 ±0.68) but less than vacuum freeze dried (L=95±0.21) . The purity of pullulan polysaccharides was 91.07% which was obtained by spray drying, and exhibited the better solubility and colour. The vacuum freeze dried product had the best solubility, but it had long time and high cost. Among the three drying methods, spray drying was the most suitable for the actual industrial production.