Abstract:Using cassava starch as the raw material, hydroxypropyl starch was prepared using the ethanol solvent method, and dually modified starch was obtained after the hydroxypropyl starch was treated with glutaric anhydride as an etherification agent. The microstructure and properties of the starch sample were investigated by Fourier transform infrared spectrometer (FT-IR), scanning electron microscope (SEM), and DV-I Prime rotational viscometer. The FT-IR results showed a new hydroxypropyl absorption peak at 1287 cm-1 in the hydroxypropyl starch, and new esterification absorption peaks at 1733 cm-1 and 1555 cm-1 in the hydroxypropyl-glutaric anhydride dually modified starch, which indicated that glutaric acid functional groups and hydroxypropyl groups were attached to the native starch. The surface morphology changes of starch granules before and after the dual modification indicated that the reaction occurred on both the surface and the interior of the starch granules. The rotational viscometry results indicated that the viscosity and rheological properties of the hydroxypropyl-glutaric anhydride-modified starch were significantly improved after the dual modification. When the degree of substitution (DS) was 0.0362, the paste viscosity increased from the original 1800 mPa·s to 12100 mPa·s, which was 6.72 times that of the hydroxypropyl starch.
