Impact of chitosan-capric acid nanogels incorporating thyme essential oil on stability of pomegranate seed oil-in-water Pickering emulsion

Abstract

The aim of this study was to obtain a stable pomegranate seed oil (PSO)-in-water Pickering emulsion stabilized by chitosan (CS)-capric acid (CA) nanogels incorporating thyme essential oil (TEO). Firstly, CS-CA nanogels were synthesized at different ratios of CA to CS (0.25:1, 0.5:1 and 0.75:1). Scanning electron microscopy images showed that by increasing the CA to CS ratio, the uniformity of particles was increased. In the following, CS-CA nanogels were used to stabilize PSO-in-water emulsions. The findings revealed that the most stable emulsion was obtained at pH 8, CA-to-CS ratio of 0.5:1 and oil-to-nanogel ratio of 10:1. In addition, interfacial structure of emulsion droplets indicated that the CS-CA nanogels contributed to the stability of emulsion through both the formation of an interface layer and a network on the surface of dispersed droplets. Finally, the oxidative stability and microstructure of the emulsions stabilized by CS-CA nanogels incorporating TEO (0.1%) were evaluated. The results showed that TEO increased the oxidative stability of the emulsion and reduced the emulsion droplet size.