Abstract: Most biologically active small molecules or nutrients have poor water solubility, making it difficult for the human body to absorb and utilize them.Meanwhile, these small molecules are easily oxidized or decomposed by external factors(light, heat, extrusion vibration, strong acid/base, etc.)during the transportation, preservation or processing of these small molecules.Therefore, it is necessary to achieve high-efficiency loading and stable release of hydrophobic active molecules, as well as good biocompatibility to the human body.The drug-loaded microcapsules not only improve the absorption and availability of hydrophobic small molecules, but also can exert their characteristics in packaging materials.In this study, curcumin was used as a representative hydrophobic active molecule as a model drug, and starch nanoparticles were used to prepare curcumin-loaded microcapsules.The physicochemical properties(molecular weight distribution, microstructure, particle size distribution and crystalline configuration)of starch nanoparticles were studied by using ultrasonic-assisted emulsification to prepare starch nanoparticles with controllable particle size.On this basis, curcumin was successfully loaded into the inner cavity of starch nanoparticles by solvent exchange method, and the loading amount of curcumin by starch nanoparticles was determined.The position of curcumin in the microcapsule system was detected by fluorescence localization method combined with laser confocal microscopy, and its thermal stability, crystalline configuration, binding mode, and free radical scavenging ability in vitro were measured.In order to improve the bioavailability of bioactive hydrophobic small molecules and the stability of curcumin during the processing of starch-based degradable active films, starch nanoparticles were prepared by ultrasonic-assisted emulsion droplet control method using debranched waxy corn starch as raw material.Curcumin was loaded and added to starch-based degradable films for active bread packaging applications.The main conclusions were as follows: Starch nanoparticles were formed from short amylose with a polymerization degree of 12 by spontaneously forming a left-handed helical structure.The particle size distribution was 56-254 nm, the appearance was round or oval, and the interior showed a hollow structure.Subsequently, curcumin was loaded into the interior of the starch nanoparticles by the solvent exchange method to form microcapsules, and the V-shaped crystalline structure was formed through hydrogen bonding and hydrophobic interaction.Meanwhile, the microcapsule structure had good thermal stability, which increased the stable temperature of curcumin from 200 ℃ to 250 ℃.In addition, the loading rate of curcumin by starch nanoparticles reached 75.5 mg/g, and the free radical scavenging efficiency reached 59.3%.Therefore, starch nanoparticles had good biocompatibility, improved the stability and solubility of curcumin, and could improve the absorption and utilization of human body.