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

炊飯米澱粉の老化における分子ダイナミクスに及ぼす米に対する水の割合の影響; ゲル化状態における非晶質構造への示唆

平田 芳信*; 中川 洋   ; 山内 宏樹   ; 金子 耕士   ; 萩原 雅人   ; 山口 秀幸*; 今泉 鉄平*; 西津 貴久*

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

中性子準弾性散乱(QENS)を用いて、炊飯米澱粉の老化における分子ダイナミクスに及ぼす米に対する水の割合の影響を調べた。X線回折と示差走査熱量測定の結果、炊飯用米澱粉の結晶化度にはほとんど差が認められなかったが、再結晶化の程度とエンタルピーの変化は、加水量の増加とともに小さくなることがわかった。QENS測定の結果、ゲル化試料の弾性非干渉性構造因子(EISF)値は、炊飯加水量の増加とともに小さくなり、加水量の多いゲル化米澱粉のダイナミクスが空間的に拡張していることがわかった。

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.