Large scale structure of wheat, rice and potato starch revealed by ultra small angle X-ray diffraction

Rice, wheat, and potato starches were investigated using ultra-small angle X-Ray diffraction (USXRD) in the range of 100–58,000 Å. The results showed trends consistent with the known sizes of starches. However, the observed Rg values for the scattering substances lie in the 100–300 nm range, very much in the low end of the known starch granule size distributions (and below the resolution of the light microscope) suggesting different, perhaps interesting, structures than those observed by light microscopy. Thus what were detected may possibly be the sizes of the crystalline regions postulated to occur in individual starch granules.