Effect of the ratio of water to rice on the molecular dynamics of cooked rice starch during retrogradation; Implications for amorphous structure in gelatinized state

Hirata, Yoshinobu*; Nakagawa, Hiroshi   ; Yamauchi, Hiroki   ; Kaneko, Koji   ; Hagihara, Masato   ; Yamaguchi, Hideyuki*; Imaizumi, Teppei*; Nishizu, Takahisa*

We used quasi-elastic neutron scattering (QENS) to investigate the effect of the ratio of water to rice on the molecular dynamics of cooked rice starch during retrogradation. X-ray diffraction and differential scanning calorimetric measurements revealed that the degree of recrystallization and change in enthalpy were smaller with an increase in the amount of water added for cooking rice, whereas little difference in the crystallinity of the gelatinized rice starch was detected. The QENS measurements determined that the elastic incoherent structure factor (EISF) values of gelatinized samples were smaller with an increase in the amount of water added for cooking rice, indicating that the molecular dynamics of gelatinized rice starch with higher added water content were spatially more extended.