Lijun Shao,Yue Sun,Jin Liang,Meiqing Li,Xueling Li
Different decolorization methods have different effects on the properties of polysaccharides . In this study, polysaccharides extracted from Thesium chinense Turcz ( T. chinense ) were decolorized using either hydrogen peroxide (H 2 O 2 ), which has been previously reported, or activated carbon. To begin, the conditions for decolorization by activated carbon were optimized through single factor experiments and orthogonal modeling and were predicted to be best at 0.5% (w/w) activated carbon, pH 5.0 and 40 °C in a water bath for 60 min. Following treatment by the two methods, the structures of the decolorized polysaccharides were compared. The samples treated by activated carbon (CTP) had higher molecular weight (Mw: 3.064 × 10 5 g/mol) and more sulfate groups (14.33%, w/w), whereas the samples treated by H 2 O 2 (HTP) had lower Mw (8.349 × 10 4 g/mol) and more uronic acid (35.02%, w/w). The antioxidant capacities of the two samples were analyzed by free radical scavenging (DPPH, hydroxyl and ABTS) and cell antioxidant activity (CAA). The HTP showed a better scavenging effect on free radicals and a higher CAA. Together, the results showed that various decolorization methods differentially influence the characteristics of the polysaccharides extracted from T. chinense .
The purpose of this research was to develop an efficient and non-destructive method for decolorizing of polysaccharides extracted from Isaria cicadae Miquel by magnetic chitosan microspheres (MCM). The optimum decolorization parameters were achieved by response surface methodology as follows: the MCM amount was 8.0%, the adsorption temperature was 48 °C, the adsorption time was 82 min and the pH was 7. Under these optimal conditions, the Dr%, Rr%, and Kc were 90.31 ± 0.12%, 95.40 ± 0.11% and 19.66 ± 0.49, respectively. MCM adsorption of pigment molecules was a spontaneous and endothermic process that could be fitted with the pseudo-second-order equation and the Freundlich equation. Besides, the adsorption mechanism could be controlled by multiple-diffusion steps, including film diffusion and intra-particle diffusion. Furthermore, MCM is a recyclable material. Adsorption with MCM is a promising method to remove pigment molecules of polysaccharide, it may replace the traditional decolorization method.
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