Investigating structural and property modifications in starch from waxy, stick, and H37 sorghum varieties: Advancing starch structure understanding and applications

This study investigated the changes in the structure and properties of starch derived from waxy, stick, and H37 sorghum varieties at various stages of development. The results indicated that as sorghum plants matured, the shape of starch granules became distorted, their size gradually increased from 5 µm to 20 µm, and distinct porous and inner growth rings developed. Furthermore, there were irregular fluctuations in the levels of amylose and CLD. Notably, it was observed that the amylose content (>20%) played a limiting role in the crystallinity of H37 starch, as confirmed by XRD, 13C CP/MAS NMR, and SAXS analyses. Interestingly, the influence of CLD on factors such as lamellar thickness (6.4–7.1 nm), degree of crystalline order, double-helix structure, and the ratio of crystalline to amorphous starch granules (26–31%) harvested at different developmental stages in various sorghum varieties was more pronounced than the impact of amylose content. The study also conducted an in-depth correlation analysis between the structural and property aspects, including thermodynamics, viscoelasticity, and hydrolysis rate, which provides valuable insights for the precise modification of starch structure.