Assembly of spherical-shaped resistant starch nanoparticles to the oil droplet surface promotes the formation of stable oil in water Pickering emulsions

Abstract

The use of starch-based nanoparticles in stabilizing Pickering emulsions has gained momentum since it offers a versatile, biocompatible, and sustainable approach with a wide range of applications. In the present study, starch nanoparticles produced using a sequential 3-step physical process were used as particle stabilizers to create Pickering emulsions. According to our results, high amylose starch nanoparticles can provide long-term colloidal stability to Pickering emulsions. The concentration of the particle-based stabilizer affected the size of the droplets, which in turn had an impact on the stability properties of the produced emulsions. By increasing nanoparticle concentration, surface and interfacial tension were reduced, providing the ability to the particles to adsorb at the interface. When starch and oil concentrations were compared using Dynamic Laser Scattering (DLS) and zeta potential, smaller droplets were produced by increasing starch amount and improved stability was depicted. Rheological profiles showed that the emulsion network structure was strengthened by the addition of nanoparticles, increasing the storage (G′) and loss (G″) moduli, as well as viscosity. In conclusion, the produced emulsions can be categorized as Pickering emulsion gels. These networks, specifically at starch nanoparticle concentration of 3% w/v and 5% w/v, have the advantage of preventing phase separation, droplet coalescence, and Ostwald ripening. The formation of a strong gel network was also obtained by Confocal Laser Microscopy (CLSM). All in all, this study provides new insights into the preparation and stabilization of starch-based Pickering emulsions, as the demand for sustainable and eco-friendly solutions in food product development is growing.