Characterization of starch nanoparticles prepared by nanoprecipitation: Influence of amylose content and starch type

• The mean diameters of starch nanoparticles were mainly of 30–75 nm.
• Diameter of nanoparticles was consistent with the blocklet sizes in starches.
• The V-type crystalline was independent of the crystal type of the native starch.
• The relative crystallinity and amylose content have a high correlation.

Starch nanoparticles (SNPs) were prepared by nanoprecipitation using seven native starches, including waxy corn, normal corn, high amylose corn, potato, tapioca, sweet potato, and pea starches (amylose content 0.8%–69.0%). The structural, morphological and physicochemical properties of SNPs were systematically investigated using dynamic light scattering, Fourier transform infrared spectroscopy, X-ray diffractometry, differential scanning calorimetry and electron microscopy. Compared to micro-scale native starch (mean size of 15–49 μm), the mean particle sizes of SNPs were mainly in the range of 30–75 nm, which is much smaller than those reported in previous published literatures. Interestingly, the smaller the starch granules were, the smaller the corresponding SNPs were obtained. All SNPs exhibited a typical V-type crystalline structure, which were independent of the crystal type of the native starch. Moreover, the relative crystallinity of SNPs increased with the increasing amylose content in native starch, and a high correlation (R2 = 0.95) was observed. Compared with native starch, the gelatinization enthalpy of corresponding SNPs decreased, with the exception of high amylose corn starch.

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