Supramolecular structural evolutions of maize starch hydrothermally treated in excess water

Supramolecular structural changes of maize starch as affected by hydrothermal treatment in excess water were investigated. At a temperature slightly higher than the onset (T_o) 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 (T_p) 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.