TOCNF/Nisin-Stabilized Oregano Oil Pickering Emulsions Enhance Chitosan Quaternary Ammonium Salt/Propolis Films for...

Essential oils are difficult to disperse in hydrophilic films and may separate or volatilize during processing. We prepared chitosan quaternary ammonium salt/propolis films containing a TEMPO-oxidized cellulose nanofibril (TOCNF)/nisin-stabilized Pickering emulsion loaded with oregano essential oil. Two independent formulation variables were examined: the nisin fraction in the TOCNF/nisin particles (0-35% of particle mass) was first screened to select the emulsion stabilizer composition, whereas the selected TNO emulsion was subsequently added at 20%, 30%, 40%, or 50% (v/v) of the initial film-forming solution. At 25% nisin, encapsulation efficiency reached 88.0%, and the polydispersity index was 0.15, so this formulation was used in the films. As emulsion loading increased, the films became lighter and opacity fell from 19.75 to 4.81 A mm^-1. HCP/TNO30 reached a tensile strength of 45.18 MPa, but elongation at break decreased from 65.35% to 28.11% across the series. Water vapor and oxygen permeability were lowest at 40% loading. HCP/TNO50 had the highest radical-scavenging and antibacterial activities. It also reduced weight loss and quality deterioration during 12 days of green cherry tomato storage. No loading optimized every property. Mechanical strength and barrier performance peaked at 30% and 40%, respectively, while active preservation continued to improve up to 50%.