Preparation and characterization of broken-rice starch nanoparticles with different sizes

Broken-rice starch nanoparticles with different mean particle diameters for 100, 200, 400 and 800 nm were prepared by nanoprecipitation, alkali freezing, cross-linking and H₂SO₄ hydrolysis methods respectively, and their structural, morphological and physicochemical properties were systematically characterized. The results showed that broken-rice starch nanoparticles had higher water absorption rate, and the maximum water absorption rate was obtained from the 100 nm starch granules being 91.53%, which means an increase about 2.07-fold in water absorption rate as compared with native rice starch. The stability of native rice starch is the worst, but the viscosity characteristic value is always higher than that of starch nanoparticles in the whole gelatinization process. The FT-IR spectrum showed that only starch nanoparticles prepared by cross-linking method showed the characteristic peak of secondary amide structure at 1714 cm^-1, but the structure of was basically the same as native starch. The X-ray diffraction pattern revealed that there were obvious characteristic diffraction peaks near 2θ for 15°, 17°, 19° and 23° for the 800 nm starch nanoparticles and native rice starch, while the characteristic diffraction peaks of other starch nanoparticles disappeared in varying degrees due to the changed crystal structure.