Structural Characterization of Controlled Decrystallization of Cassava Starch

Abstract

AbstractNative starch granule has a complex crystalline structure. Controlled decrystallization cassava starch (CDCS) was prepared by the alcohol–alkali method. Polarized microscopy, scanning electron microscopy (SEM), X‐ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) analysis of the CDCS are carried out to investigate its structural information. The results show that the relative crystallinity (RC) of the processed cassava starches can be reduced from 25.56% to 17.90% by adjusting the concentration of sodium hydroxide while keeping the integrity of the starch granule. During the decrystallization process, as the sodium hydroxide concentration is increased from 0.25 to 1.25 mol L−1, the polarized light of the starch granules disappear from the inside to the outside, and the X‐ray diffraction peaks of native cassava starch (NCS) disappear sequentially from 17.16°, 23.04°, 15.08°, to 17.83°. On the other hand, the FTIR peaks of the NCS centered at 1645 cm−1 is shifted to about 1600 cm−1, and the intensity of the peaks at 3424, 2929, 1645, and 1017 cm−1 become weaker with decrystallization process. This study provides valuable data and a theoretical basis to understand the mechanism of the controlled decrystallization of cassava starch.