Supramolecular structure of A- and B-type granules of wheat starch

The supramolecular structure of the A- and B-type granules of wheat starch was compared. Polarized light microscopy, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) were used to study the granular, crystalline, and short-range structures. The A- and B-type granules displayed a typical A-type crystalline structure with the degrees of crystallinity of 31.95% and 29.38% respectively. In addition, the B-type granules had some V-type crystallites. The nanostructure and fractals were characterized by small angle X-ray scattering (SAXS), which showed that the average thickness of the lamellae of the A-type granules was larger, while the B-type granules possessed a higher degree of ordering in the lamellar regions. A second order reflection was found in both A- and B-type granules, which was proposed due to the crystalline lamellae of the semicrystalline lamellae. The A- and B-type granules had mass and surface fractal structures respectively.