Characterisation of sorghum starch granules using SAXS: effects of moisture on crystallinity and structure

In order to further characterise sorghum starch as a potential ingredient in food formulations, starch granules have been extracted from sorghum flour and characterised. The lamellar structure of granules and the uptake of water under ambient conditions have been investigated using small-angle X-ray scattering (SAXS). The lamellar structure was affected by the uptake of water and crystallinity was disrupted as water was absorbed. The diameter of sorghum granules had a bimodal distribution and the lamellar patterns were similar to those of other cereal starches. Moisture uptake occurred within the first four hours of exposure to water and SAXS provides a valuable technique for further studies of granular starch, including changes during the uptake of water.