Effect of repeated heat-moisture treatments on the structural characteristics of nanocrystals from waxy maize starch.

The effect of repeated heat-moisture treatment (RHMT) on the structural characteristics of waxy maize starch nanocrystals was investigated. Compared with native waxy maize starch (WMS), waxy maize starch nanocrystals (WMSNs) changed the crystalline pattern from A-type to B-type, and displayed the lower crystallinity (RC), molecular order (MO), enthalpy (∆H) and double-helix (DH) content, indicating a reduction in the long- and short-range orders of starch molecules. Single heat-moisture treatment significantly increased values, including RC, MO, α (power law exponent obtained by SAXS), ∆H, DH, and the melting temperatures (T, T and T), while repeated heat-moisture treatment further increased values of these parameters except ∆H, indicating the reinforcement of the long- and short-range orders of WMSNs.