Phenolic Acid-Based Self-Assembled Nanoemulsions for Fruit Preservation and Hydrophobic Drug Delivery

Nanoemulsions, serving as effective and conventional carriers for hydrophobic active ingredients (e.g., functional lipids and plant-derived bioactive substances), have long been studied for nutritional and biomedical applications. However, conventional preparation methods are generally plagued by elaborate designs, complex processes, and synthetic surfactants with poor degradability and limited functionality. Here, we report a green and facile strategy to develop multifunctional nanoemulsions stabilized solely by natural phenolic acids via simple ultrasonication, which can rapidly and efficiently load natural essential oils and hydrophobic molecules. The particle sizes of the nanoemulsions prepared using different phenolic acids as emulsifiers range from 267.6 ± 1.0 to 408.3 ± 7.4 nm, with ζ-potentials varying from −8.3 ± 0.5 mV to −32.1 ± 1.4 mV. When incorporated with a chitosan– dextran film, the nanoemulsions reduce the water vapor permeability (WVP) of the polysaccharide film by 22.9%, and the antibacterial rates against Escherichia coli and Staphylococcus aureus reach 98.6 and 72.4%, respectively. Compared with strawberries without any preservation treatment, those preserved by the nanoemulsion composite films showed significantly lower losses of weight (15.79 vs 23.55%), total soluble solids (18.71 vs 48.33%), and titratable acidity (32.24 vs 67.42%) at the end of the storage period, indicating that the film can effectively prolong the shelf life of strawberries. Furthermore, these emulsions achieve efficient loading of different essential oils and hydrophobic bioactive substances, which can readily be incorporated with various natural products to prepare uniform hydrogels for sustained release, demonstrating substantial potential for clinical hydrophobic drug delivery. This work establishes a versatile, natural platform for sustainable preservation and therapeutic application.