Effects of the Noncyclic Cyanamides on the Gelatinization of Waxy Corn Starch

Abstract

Effects of noncyclic cyanamides on the gelatinization of waxy corn starch (WCS) suspension, containing amylopectin as a major component, were examined by analyses of differential scanning calorimetry, X-ray powder diffraction, and Fourier-transform infrared spectroscopy by the attenuated total reflection method. The temperature for the gelatinization of WCS suspension decreased by addition of urea, thiourea, and biuret in comparison to that without additives. These results suggested that the amino, imino, carbamoyl, and thiocarbamoyl groups of additives might have affected the collapses of the intra- and intermolecular hydrogen bonds of the WCS by forming hydrogen bonds with hydroxy groups in the WCS. However, the temperature slightly increased with the increase of the concentration of guanidiniurn salts except for guanidine hydrochloride. The inhibition effect on the gelatinization might have been explained by the anion-constituting guanidinium salts.