Preparation and characterisation of the oligosaccharides derived from Chinese water chestnut polysaccharides

• Optimum hydrolysis conditions were 4 h, 80 °C, and 2.5% H2O2.
• The CWCOs had strong HRSA at the concentration of 100 μg/mL.
• The CWCOs had strong DRSA at the concentration of 100 μg/mL.

Hydrogen peroxide (H2O2) is a strong oxidant that cleaves glycosidic bonds in polysaccharides. In this study, the oligosaccharides were prepared by removing the starch from Chinese water chestnuts through hydrolysis using α-amylase and then hydrolysing the remaining polysaccharides with H2O2, during which the oligosaccharide yield was monitored. The yield of oligosaccharide was affected by reaction time, temperature, and H2O2 concentration. Extended reaction times, high temperatures, and high H2O2 concentrations decreased oligosaccharide yield. Under optimum conditions (i.e., reaction time of 4 h, reaction temperature of 80 °C, and 2.5% H2O2 concentration), the maximum oligosaccharide yield was 3.91%. The oligosaccharides derived from Chinese water chestnuts polysaccharides exhibited strong hydroxyl and 2,2-diphenyl-β-picrylhydrazyl radical scavenging activity when applied at a concentration of 100 μg/mL. The results indicate that the oligosaccharides derived from Chinese water chestnuts polysaccharides possessed good antioxidant properties and can be developed as a new dietary supplement and functional food.