Preparation and Characterization of Zinc and Frankincense-Loaded Carboxymethyl Cellulose Nanoemulsions: Their Impact on Antifungal Activity, Biochemical Properties, and Shelf-Life Extension of Valencia Orange

Natural preservation methods have grown in prominence and demand as a means of preserving fruits and prolonging their shelf life rather than synthetic additions. Therefore, this study is directed to investigate carboxymethyl cellulose (CMC) loaded with frankincense and zinc ions nanoemulsion as food coating material to assess their antifungal activity and efficacy in protecting the quality of Valencia orange during storage. The nanoemulsions were synthesized using the solvent evaporation technique and characterized using transmission electron microscopy (TEM) and Fourier-transform infrared spectroscopy (FTIR). The antifungal activity was tested both in vitro and in vivo against the harmful fungus Penicillium commune and Aspergillus niger. Fresh mature oranges were coated with different prepared nanoemulsions. Biochemical parameters (total soluble solids percentage, total acidity, and ascorbic acid content), and physical parameters (weight loss, decay percentage, and firmness) were tested at different time intervals up to 180 days. The TEM results illustrate the presence of agglomerated nanoparticles of frankincense and the effect of zinc in the separation and formation of well-dispersed nanoparticles with an average diameter of 28.7±14nm. The in vitro antifungal activity results indicated that the nanoemulsion of CMC loaded with zinc and frankincense showed maximum activity against Penicillium commune with an inhibition efficiency of 33.3% followed by Aspergillus niger with an inhibition efficiency of 28.4%. Moreover, in-vivo antifungal activity showed the pronounced effect of CMC loaded with Zn and frankincense against the prevention of growth of both pathogens with weak growth of Aspergillus niger was observed after 30 days. The biochemical properties of Valencia orange, including total soluble solids (TSS), acidity, and vitamin C content, exhibited significant improvements when treated with the zinc and frankincense-loaded CMC nanoemulsion. Additionally, weight loss and decay percentage were significantly reduced, while fruit firmness was notably enhanced, indicating improved structural integrity and extended freshness. These improvements suggest that nanoemulsion effectively enhances cold storage preservation by maintaining the fruit’s physicochemical quality over a storage period of up to 180 days. These findings underscore the potential of CMC-based nanoemulsions as a promising strategy for prolonging the shelf life and preserving the quality of Valencia orange under refrigerated conditions.