Abstract: In order to provide useful information to explore the mechanism of the effect of annealing treatment on the physicochemical properties of corn starch, we evaluated the pasting properties, thermal properties, swelling power, crystalline structure, birefringence, and morphological structure of corn starches with different amylose contents (normal corn starch (NCS) and waxy corn starch (WCS)) annealed at different temperatures for different periods. The results showed that annealing treatment affected the amorphous zones of NCS and WCS, but exerted no effects on their crystal types. The thermal stabilities and anti-shear abilities were enhanced significantly after annealing. Annealing treatment retarded the retrogradation and gelatinization of the two starches and significantly reduced the peak viscosity and swelling power (P < 0.05). Annealing temperature up to 60 ℃ enhanced the above effects, leading to a significant decrease in the gelatinization enthalpy and the relative crystalline degree and obvious destruction of the morphological structure. However, prolonged annealing time did not significantly retard the retrogradation of NCS and WCS starches while having no significant effect on the gelatinization enthalpy, swelling power, or morphological structure.

Key words: normal corn starch, waxy corn starch, annealing treatment, physicochemical properties, retrogradation