Effect of polydextrose on the retrogradation of rice starch gel

To investigate the effect of polydextrose (PD) on the retrogradation of rice starch (RS) gel, rapid viscosity analyzer (RVA), different scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to investigate the change of viscosity, thermodynamic properties, crystal and micro structure of rice starch gel. RVA results showed that addition of polydextrose lowered the peak viscosity, final viscosity, breakdown and setback values, but increased the gelatinization temperature of rice starch. DSC results showed the gelatinization and retrogradation enthalpy significantly decreased with the increasing polydextrose concentrations. Moreover, the relative crystallinity also decreased from 14.09% to 8.61%. The microscope structures images showed polydextrose made the pore of rice starch gel smaller, and the surface more intensive and smoother. These results suggested that the addition of polydextrose could restrain the recrystallization of rice starch gel and inhibit the retrogradation of rice starch gel.