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 refle
ction method. The temperature for the gelatinization of WCS suspension decr
eased by addition of urea, thiourea, and biuret in comparison to that witho
ut 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 bo
nds with hydroxy groups in the WCS. However, the temperature slightly incre
ased with the increase of the concentration of guanidinium salts except for
guanidine hydrochloride. The inhibition effect on the gelatinization might
have been explained by the anion-constituting guanidinium salts.