Expansion of the cavity in the sago starch crystalline structure by water molecules

Abstract

 X-ray diffraction, one of the useful tools for the structural analysis of starch, was used for analysis of the reflection surface of a crystalline structure, resulting in determining the distance of the interlayered structure. The X-ray diffraction peak at about 5 to 6° for 2Θ Cu Kα of water-added starch with type B and type C crystallinity shifted to the smaller degree side than that of the original starch, suggesting the expansion of the interlayered distance by the invasion of water molecules. The invasion of water molecules into the structure expanded the lattice spacing of the cavity from 1.56 nm to 1.61 nm, which corresponded to about 1/6 of the diameter of a water molecule.