Pickering emulsions of zein nanoparticles co-stabilized by Tween 20: An effective strategy to stabilize citral in low pH environment

Abstract

The demand for surfactant-free emulsions is growing significantly in food industry. Herein, we report the fabrication of zein nanoparticles, modified their surface hydrophobicity with Tween 20, and used them to stabilize various formulations of Pickering emulsions designated as ZT0 %, ZT5 %, ZT10 %, ZT15 %, ZT20 %, and ZT25 %, for preventing the acid-catalysed degradation of citral at 25 °C. Our results suggest that, as the concentration of Tween 20 increases, the droplet size of the emulsions first increases and then decreases, whereas the mechanical strength continuously increases. Citral encapsulated in ZT25 % shows maximum physicochemical stabilization as determined by visual, olfactory and HPLC analysis, and when released in saline shows maximum antioxidant activity due to the favorable charge characteristics on Pickering emulsifiers, and the existence of hydrophobic ⇋ electrostatic interaction. As compared to prior literature, our work represents a significant advancement in fabrication of zein nanoparticles (ZNPs), their stabilization using Tween 20 and the formation of appropriate Pickering emulsions stabilized by Tween 20 modified ZNPs appropriate for modifying the interfacial characteristics of the emulsion for enhanced physicochemical stability, excellent aroma profile, controlled release rate, and improved antioxidant activity of encapsulated citral under harsh acidic conditions. Moreover, the novel Chemical Kinetic Method has been applied to analyze and interpret the citral stability as a function of interfacial parameters. The study, therefore presents a novel particle-surfactant complex interface, having great potential for the encapsulation, protection, and release of citral from the acidic food/pharmaceutical formulations.