Development of aqueous dispersions of zein–inulin nanoparticles: Influence of formulation variables on physical properties

Background: Zein-based nanoparticles exhibit considerable potential for pharmaceutical and food applications. Incorporating inulin, a prebiotic polysaccharide, can improve their functional performance. Owing to the distinct solubilities of zein and inulin in aqueous ethanol, zein– inulin nanoparticles can be prepared through precipitation using their respective anti-solvents. Objectives: This study aimed to systematically develop zein–inulin nanoparticles using the antisolvent precipitation method, with a focus on investigating the effects of formulation variables on particle characteristics and dispersion properties. Materials and Methods: Zein–inulin nanoparticles were prepared using an anti-solvent precipitation method. Zein and inulin were separately dissolved in aqueous ethanol and water, respectively. The zein solution was then added to the inulin solution under homogenization. A central composite design was employed to investigate the effects of the zein-to-inulin ratio (70:30 and 90:10) and ethanol concentration (70% and 90% v/v) in aqueous ethanol, used as the solvent for zein, on the nanoparticle characteristics (particle size, polydispersity index PDI, zeta potential) and the dispersion properties (pH and viscosity). Results: The results demonstrated that zein–inulin nanoparticles could be readily prepared using the anti-solvent precipitation method. The observed negatively charged surface indicated the presence of inulin on the nanoparticle surface. Particle size and dispersion properties were significantly influenced by both the zein-to-inulin ratio and ethanol concentration, whereas PDI and zeta potential were primarily affected by ethanol concentration. The verified optimal formulation consisted of a zein-to-inulin ratio of 80:20 and an ethanol concentration of 80% v/v. Conclusion: These findings support the further development of zein–inulin nanoparticles for active ingredient encapsulation and the future exploration of their aqueous dispersion as filmforming agents derived from edible and renewable materials.