Effects of D‐psicose on gelatinization and retrogradation of rice flour

The rare sugar D ‐psicose was shown to have an ability to promote gelatinization of rice flour and to retard its retrogradation. The force at fracture of rice cake samples containing sucrose but no D ‐psicose increased after refrigerated storage, while that of the samples containing D ‐psicose or trehalose remained largely unchanged. Both the gelatinization temperature and enthalpy determined using differential scanning calorimetry were lower in the presence of D ‐psicose than sucrose or trehalose. X‐ray diffraction peaks arising from crystalline structures in starch disappeared upon heating up to 68°C in the presence of D ‐psicose and 75°C in the presence of sucrose or trehalose. The reduction in the dielectric relaxation strength due to starch retrogradation was more pronounced in the presence of sucrose or trehalose than D ‐psicose. The present results suggest that D ‐psicose facilitates melting of the crystalline structure in rice flour upon heating and inhibit re‐crystallization during storage.