Pickering emulsion stabilized by hollow Zein/SSPS nanoparticles loaded with Thymol: Formation, characterization, and application in fruit preservation

Abstract

Using Pickering emulsion (PE) as the carrier of active compounds in bio-based coatings constitutes a highly promising research domain. This study focused on creating a food-grade, biocompatible, and antibacterial PE to coat fresh fruits and vegetables, extending their shelf life. Hollow zein/soluble soybean polysaccharide nanoparticles loaded with thymol (H-ZSH/T) were produced using NaHCO₃ as a sacrificial template to stabilize PE. The results revealed that the prepared hollow zein-based nanoparticles had superior dispersibility and structure compared to solid nanoparticles, with an average particle size of 92.24-95.18 nm and polydispersity index (PDI) of 0.151-0.179. Thymol was successfully encapsulated through hydrogen bonding, electrostatic attraction, and hydrophobic interactions. The zein-based nanoparticles loaded with thymol showed notable antibacterial properties against E. coli and S. aureus, with a more substantial effect on E. coli. H-ZHS/T demonstrated the highest antibacterial efficacy by disrupting bacterial cell membranes. The prepared PE was an oil-in-water type; increasing the oil fraction improved stability and droplet size while reducing the creaming index. Rheological assessments indicated elastic gel-like characteristics, ensuring both stability and uniformity. The PE coating significantly slowed the loss of fruit hardness, inhibited microbial growth, and extended the shelf life of blueberries and fresh-cut cantaloupe. These findings demonstrated that H-ZHS/T-stabilized PE is an effective and eco-friendly food coating.

Keywords: Coating; Hollow nanoparticle; Pickering emulsion; Soluble Soybean Polysaccharide; Thymol; Zein.