Optimization of Decoloration Process by Macroporous Resins and Its Chemical Properties of Strawberry Polysaccharides

The decolorization parameters of strawberry polysaccharides(SP)were optimized by different macroporous resins with the highest decolorization rate,retention rate and selection coefficient. The chemical composition,monosaccharide composition,molecular weight,spectral characteristics,antioxidant activity and inhibition of α-glucosidase and α-amylase of strawberry polysaccharides were studied. The results suggested that NKA-9 resin offered better efficiency than other tested resins. The optimal decoloration parameters of NKA-9 resin were obtained as follows:Sample initial concentration of 30 mg/mL,static decoloration time of 60 min,temperature of 50 ℃,pH value of 8.0,dynamic decoloration processing volume of 4.5 BV with the flow rate of 3.0 BV/h. Decoloration ratio,PSTS recovery ratio and selectivity coefficient were 91.24%±1.32%,78.86%±1.21% and 8.24%±0.21% respectively. Pigment impurities were successfully removed from SP solutions after treated by NKA-9 resin,but decoloration treatment decreased the antioxidant ability of SP. SP was an acidic heteropolysaccharide which mainly contained carbohydrates(78.23%±0.56%,w/w),uronic acids(8.56%±0.19%,w/w)and proteins(6.14%±0.63%,w/w). SP was composed of rhamnose,arabinose,galactose,glucose,fructose,galacturonic acid and glucuronic acid with mass ratio of 1.00:0.67:0.69:0.80:0.65:0.29:0.69.SP exhibited inhibitory activities against α-glucosidase in a mixed inhibition type,and against α-amylase in an uncompetitive inhibition type. The enzyme inhibitory effect was enhanced significantly by decoloration.