EFFECT OF THE GUANIDINE-HYDROCHLORIDE ON THE RETROGRADATION OF WAXY CORN STARCH

The effect of the guanidine hydrochloride on the retrogradation of wax y corn starch gel has been studied by using viscometer, X-ray powder d iffraction, and Fourier-transform infrared spectroscopy (FTIR). During gelation and ageing of waxy corn starch gel, a viscosity of gel incre ased with time. The salt effect on an increasing rate of viscosity of waxy corn starch gel is not recognized up to two weeks and subsequentl y the increasing rate of viscosity decreases with increasing the amoun t of guanidine hydrochloride. The swollen granules, by their mutual in teractions, form temporary network due to the hydrogen bond. Long-term increases in the modulus of starch gels were linked to a reversible c rystallization and a formation of intermolecular hydrogen bond within the granules on storage. Crystal structure of retrograded waxy corn st arch, as detected by X-ray powder diffraction, was a B-form. FT-IR stu dy suggest that all five peaks due to the hydrogen bonds overlap in th e range of 3000-3800 cm(-1) and there is a difference in spectra betwe en retrograde and native waxy corn starch gels. From these results, we proposed that the molecular structure of waxy corn starch with guanid ine hydrochloride can be attributed to the strong N-H ... O hydrogen b ond for a hard intermolecular interaction.