Abstract:Objective To study the decolorization process of Sargassum fusiforme polysaccharide and its antioxidant activity. Methods Four decolorization methods, including activated carbon, hydrogen peroxide, D101 macroporous resin and AB-8 macroporous resin, were employed to decolorize the Sargassum fusiforme polysaccharide. On the basis of single-factor experiments, the decolorization rate and polysaccharide retention rate were used as the indexes to optimize the decolorization process of Sargassum fusiforme polysaccharide using response surface methodology. Furthermore, the in vitro antioxidant activities of Sargassum fusiforme polysaccharide were evaluated both before and after decolorization. Results Upon comparing the four decolorization methods, the AB-8 macroporous resin method, which demonstrated the best decolorization effect, was selected. The optimal decolorization process conditions for this method were obtained through the response surface test design as follows: the resin addition was 10%, the polysaccharide solution pH was 7, the decolorization time was 2 h, and the decolorization temperature was 30 ℃ . Under these conditions, the polysaccharide retention rate was 72.60%, and the deproteinization rate was 69.27%. The results of the in vitro antioxidant activity demonstrated that the maximum scavenging rates of DPPH radicals and hydroxyl radicals from the Sargassum fusiforme polysaccharide after decolorization could reach 71.32% and 78.95%, respectively. The scavenging ability of Fargesia fasciata polysaccharides on DPPH free radicals and hydroxyl free radicals was weaker than that of ascorbic acid (P<0.05). Conclusion The decoloration effect of the AB-8 macroporous resin decolorization method on Sargassum fusiforme polysaccharide was superior to that of the other three decolorization methods, and the Sargassum fusiforme polysaccharides before and after decolorization exhibited moderate antioxidant activities, which can be developed and utilized as natural antioxidants.