Preparation and Characterization of Chitosan/Lemongrass Oil/Cellulose Nanofiber Pickering Emulsions Active Packaging and Its Application on Tomato Preservation

Pickering emulsification is a cutting-edge technique to stabilize emulsions using solid particles rather than conventional emulsifiers and is applicable in active packaging. Pickering emulsion-based coatings are known for good coalescence stability and long-term storage stability which can prolong the shelf life of fruits and vegetables. This study evaluates coating solutions of 2% (w/v) chitosan combined with 1% and 2% (w/v) lemongrass oil (LGO), using 0.5% (w/v) cellulose nanofibers (CNF) as the Pickering emulsion stabilizer. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to analyze film morphology. The results showed an increase in film roughness with the LGO Pickering emulsion addition. The chemical interactions within the emulsified coating and oil droplet dispersion were assessed using Fourier transform infrared spectroscopy (FTIR) and confocal laser scanning microscopy (CLSM), respectively. In films containing LGO, FTIR revealed increased peak intensities and the presence of a new peak, while CLSM results showed uniform oil droplet distribution throughout the emulsified coating. Chitosan film incorporating LGO Pickering emulsions exhibited significantly (p < 0.05) increased film thickness, a* value, b* value, total color difference (ΔE), opacity, elongation at break (flexibility), and significantly (p < 0.05) decreased film moisture content, water vapor permeability, and tensile strength (stretchability). Tomatoes were stored at 20 °C and 60% RH for 15 days, and quality parameters (weight loss, redness (a*/b*), and firmness) were assessed. The results show better weight loss (9.05%) and a*/b* values (1.44) was obtained with tomatoes coated with chitosan/1% LGO Pickering emulsions, compared to the uncoated and other coated tomatoes. In vivo, antifungal activity of the chitosan coating with the LGO Pickering emulsion against tomatoes inoculated with Botrytis cinerea, stored at 25 °C and 60% RH, demonstrated significantly (p < 0.05) increased lesion diameter inhibition percentage (LDI%) from 34.46–57.44%. In this study, CH/1% LGO Pickering emulsions active packaging was the best treatment.