Novel concentrated O/W emulsion co-stabilized by like-charged chitosan nanoparticle and ethyl lauroyl arginate (LAE) surfactant at very low dosages

Abstract

Emulsions co-stabilized by like-charged cationic ethyl lauroyl arginate (LAE) and positively charged chitosan/sodium tripolyphosphate (CS-TPP) nanoparticles at low doses were prepared. The effects of CS-TPP nanoparticle concentration, LAE concentration, and pH on storage stability and mean droplet diameter were investigated, and the emulsion microstructure was examined by confocal laser scanning microscopy. The emulsions formed by LAE and CS-TPP were O/W emulsions, different from W/O emulsions formed by CS-TPP alone. The stability of the emulsions co-stabilized by LAE and CS-TPP was superior to that of the emulsions stabilized by LAE alone or CS-TPP nanoparticles alone. The emulsions could maintain good stability with 0.5 mM LAE and 0.08 wt% CS-TPP at pH ranging from 3.5 to 5.5. After standing and layering, the upper cream layer of CS-TPP+LAE emulsions could form stable high internal phase emulsions. For the novel emulsion, LAE dominated the formation of emulsion droplets, and adsorbed CS-TPP nanoparticles played a crucial role in the emulsion stability. The adsorbed CS-TPP nanoparticles discretely attached to oil droplets could form a strawberry-like construct, which could prevent the coalescence of emulsion droplets through electrostatic repulsion and steric hindrance. This work demonstrates the capacity of low dose food-grade emulsifiers and stabilizers to form stable emulsions.