Nanoemulsion-Based Nanocoatings Containing Essential Oils for Active Packaging: Production Technologies, Characterization and Microbial Control

Essential oils (EOs) have attracted considerable interest as natural antimicrobial agents for food preservation due to their broad biological activity. However, their volatility, susceptibility to oxidation, limited water dispersibility, and potential sensory effects restrict their direct application. Incorporation into nanoemulsions (NEs) can improve EO dispersion, physicochemical stability, and interaction with microbial cells, while their incorporation into biopolymer matrices enables the development of functional nanocoatings with potential for active-agent controlled release. This review critically examines how formulation composition and preparation conditions influence the physicochemical stability, mechanical properties, barrier performance, release kinetics, and antimicrobial activity of EO-based nanoemulsion nanocoatings. Recent evidence regarding their application in meat, dairy products, and postharvest produce is discussed, with emphasis on the interactions among EO composition, droplet characteristics, polymeric matrices, and processing conditions. In addition, the regulatory framework governing active food packaging is discussed, highlighting challenges associated with food-contact materials, essential oils, nanotechnology, migration, safety assessment, and consumer information. Overall, the available evidence indicates that rational optimization of both nanoemulsion formulation and nanocoating structure is essential for translating these systems into effective and commercially viable antimicrobial technologies.