Physicochemical properties of maize and sweet potato starches in the presence of cellulose nanocrystals

Abstract

The goal of this research was to evaluate the effect of cellulose nanocrystals (CNC) on the gelatinization, pasting, and short- and long-term retrogradation properties of normal maize starch (NMS), waxy maize starch (WMS), and sweet potato starch (SPS). Differential scanning calorimetry (DSC) data indicated that the addition of CNC did not significantly change the gelatinization temperatures of starch, but the enthalpy change values slightly decreased. Rapid visco-analyzer (RVA) data suggested that CNC slightly increased the peak viscosity of NMS and SPS, while it reduced the setback values of SPS, indicating the retardation of short-term SPS retrogradation. Further, the dynamic time sweep of starches with CNC demonstrated remarkable inhibition of the short-term retrogradation of NMS and SPS. DSC results showed that 10% (w/w, based on starch) addition of CNC significantly (p < 0.05) decreased the retrogradation enthalpy change of NMS, WMS, and SPS. X-ray diffraction (XRD) results exhibited that the relative crystallinity of retrograded NMS, WMS, and SPS decreased as the content of CNC increased. Both DSC and XRD results suggested that there was really a dominant inhibiting influence of CNC on the recrystallization of amylopectin, and thus, the long-term retrogradation of starch was hindered. It could therefore be concluded that CNC apparently inhibited not only the short-term retrogradation of amylose, but also the long-term retrogradation of amylopectin.