Zein-polysaccharide hydrogel loaded with basil and oregano essential oils: Insights of fabrication, stability and antibacterial mechanism

Composite porous hydrogels have recently attracted interest for controlling foodborne pathogens. However, the fabrication mechanism of composite polysaccharide, essential oils and zein self-assembled nanoparticles, as well as the antibacterial effect, has not been investigated. In this study, a composite porous hydrogel was prepared by incorporating zein nanoparticles encapsulating basil essential oil (BEO) and oregano essential oil (OEO) into a carrageenan‑sodium alginate matrix. The combination of BEO and OEO improved the dispersibility of zein nanoparticles, and enhanced the cross-linking density of CS-zein-BEO/OEO, resulting in the highest viscosity and storage modulus (G'). Scanning electron microscopy (SEM) and atomic force microscopy (AFM) revealed that CS-zein-BEO/OEO formed a dense network structure with lower surface porosity (14.45 %) and Ra value (109 nm) compared with CS-zein-BEO and CS-zein-OEO. FTIR and XRD analyses confirmed that the enhanced structural stability was driven by synergistic hydrogen bonding, electrostatic interactions and hydrophobic forces. Antibacterial assays showed that CS-zein-BEO/OEO exhibited superior broad-spectrum activity, achieving up to 99.02 % inhibition against B. cereus through membrane disruption and reactive oxygen species (ROS) induction. Furthermore, CS-zein-BEO/OEO coating effectively suppressed the increase in TVB-N, TVC and metmyoglobin content, maintaining color and flavor stability in the model of air-dried goose meat preservation. Overall, the CS-zein-BEO/OEO composite porous hydrogel holds great potential for preventing food spoilage and controlling foodborne pathogens.