Preparation and characterization of resistant starch type IV nanoparticles through ultrasonication and miniemulsion cross-linking

This study aimed to assess the properties of resistant starch type IV (chemically modified starch, RS4) prepared from a new and convenient synthesis route by using ultrasonication combined with water-in-oil miniemulsion cross-linking technique. A three-factor Box-Behnken design and optimization was used to minimize particle size through the developed RS4 nanoparticles. The predicted minimized Z-Avel (576.1 nm) under the optimum conditions of the process variables (ultrasonic power, 214.57 W; sonication time, 114.73 min; and oil/water ratio, 10.54:1) was very close to the experimental value (651.0 nm) determined in a batch experiment. After preparing the RS4 nanoparticles, morphological, physical, chemical, and functional properties were assessed. Results revealed that RS4 nanoparticle size reached about 600 nm. Scanning electron microscopy images showed that ultrasonication induced notches and grooves on the surface. Under polarized light, the polarized cross was impaired. X-ray diffraction results revealed that the crystalline structure was disrupted. Smaller or no endotherms were exhibited in DSC analysis. In the FTIR graph, new peaks at 1532.91 and 1451.50 cm−1 were observed, and pasting properties were reduced. Amylose content, solubility, and SP increased, but RS content decreased. Anti-digestibility remained after ultrasonication. The prepared RS4 nanoparticles could be extensively used in biomedical applications and in the development of new medical materials.