Determination of starch crystallinity with the Fourier-transform terahertz spectrometer.

We measured the terahertz (THz) spectra of native, amorphous, and dried starches derived from corn and potato using the Fourier-transform (FT) system and compared these spectra to the X-ray diffraction (XRD) patterns. Both native corn and potato starches had seven absorption peaks in the terahertz regions, but five peaks were observed in the amorphous states. While spectral changes slightly occurred in corn starch even after drying, increase and decrease in the terahertz peak intensities were obtained in potato starch during drying.