Supramolecular structural evolutions of maize starch hydrothermally treated in excess water

Abstract

Supramolecular structural changes of maize starch as affected by hydrothermal treatment in excess water were investigated. At a temperature slightly higher than the onset (To) of gelatinization endotherm (G), an increase in the size of the cavity at the granule core and a sharp decrease in the ordering degree of the semi‐crystalline lamellae occurred, together with the scattering objects apparently becoming looser. When the temperature approached close to the peak temperature (Tp) of endotherm G (70°C), the semi‐crystalline lamellae disappeared, accompanied by the emergence of a dual fractal structure. This suggests that the molecules of swollen maize starch displayed inhomogeneity on nanoscale, with a mass fractal structure at a higher scale level constituted by the scattering objects at a lower scale level. Additionally, it is proposed that a reduction in starch crystallites could enhance the degree of mixing between the crystalline and amorphous materials. The results enable a better understanding of starch supramolecular structural evolutions during the hydrothermal treatment in excess water.