Effects of drying temperature of corn from the center and extremities of the corncob on morphology and technological, thermal, and pasting properties of isolated starch

Abstract

The corn grains from the extremities of corncob are known to have a spherical shape and the grains from the center of corncob have higher length and less thickness. It is understood that these differences in grain dimensions can affect post-harvest processes and the properties of the starch isolated from these grains. Therefore, the objective was to evaluate the effects of drying temperature (60, 80, and 100 °C) of corn from the center and extremities of corncob on morphology and technological, thermal, and pasting properties of isolated starch. Increasing the drying temperature results in reduced starch extraction yield and purity, and increases the thermal resistance of the starch. When the grains from the center and extremities were separated after drying at 80 and 100 °C, there was an intensification of these changes in the starch isolated from the corn from the center of the corncob. This condition results in a higher reduction in starch extraction yield, purity, and water-binding capacity. For the corn from the center, separation before drying at 100 °C increased the starch extraction yield from 16.42 to 23.09% and the luminosity (L*) from 96.96 to 98.28 and reduced the residual protein content from 2.56 to 1.33% and yellowness (b*) from 15.55 to 11.39. The results showed that the industrial separation of corn grains with different dimensions can increase the starch extraction yield by 35–40%.