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

Kazuo OGAWA, Saisei NISHIKAWA, Isao YAMAZAKI†, Toshiaki YOSHIMURA, Shin ONO,
Seichi RENGAKUJI, Yuuko NAKAMURA and Choichiro SHIMASAKI*

Department of System Engineering of Materials and Life Science, Faculty of Engineering,
Toyama University; Gofuku 3190, Toyama-shi 930-8555 Japan
† Yayoikagaku Kogyo Co., Ltd.; Honryo 70, Fukuoka-machi, Toyama 939-0135 Japan

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 guanidinium salts except for guanidine hydrochloride. The inhibition effect on the gelatinization might have been explained by the anion-constituting guanidinium salts.


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