Determination of starch crystallinity with the Fourier-transform terahertz spectrometer

Shusaku Nakajima; Shuhei Horiuchi; Akifumi Ikehata; Yuichi Ogawa

doi:10.1016/j.carbpol.2021.117928

Determination of starch crystallinity with the Fourier-transform terahertz spectrometer

Carbohydr Polym. 2021 Jun 15:262:117928. doi: 10.1016/j.carbpol.2021.117928. Epub 2021 Mar 16.

Authors

Shusaku Nakajima¹, Shuhei Horiuchi², Akifumi Ikehata³, Yuichi Ogawa⁴

Affiliations

¹ Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai-cho, Nada, Kobe, 657-8501, Japan; Food Research Institute, National Agriculture and Food Research Organization, 2-1-12 Kannondai, Tsukuba, 305-8642, Japan. Electronic address: shu.nakajima@shark.kobe-u.ac.jp.
² Graduate School of Agriculture, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto, 606-8502, Japan.
³ Food Research Institute, National Agriculture and Food Research Organization, 2-1-12 Kannondai, Tsukuba, 305-8642, Japan.
⁴ Graduate School of Agriculture, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto, 606-8502, Japan. Electronic address: ogawayu@kais.kyoto-u.ac.jp.

PMID: 33838806
DOI: 10.1016/j.carbpol.2021.117928

Abstract

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. Similar changes in both starches during amorphization and drying were obtained in the X-ray diffraction patterns, and the correlations were found between terahertz peaks and the X-ray signals. Since the intensity of the peak at 9.0 THz was correlated with crystallinity obtained using an X-ray diffraction (r² = 0.98), our data indicate that the Fourier-transform terahertz spectrometer can be a new analytical device to measure the starch crystallinity.

Keywords: Crystallinity; Starch; Terahertz spectroscopy; X-ray diffraction.