Advances in essential oil co-encapsulation: Synergistic interactions, fabrication strategies, functional properties, and applications in food and biomedicine

Background: Essential oils are sustainable natural bioactives, yet their industrial use is constrained by instability, insolubility, and sensory limitations. While mono-encapsulation offers partial solutions, the field is shifting toward co-encapsulation—loading multiple bioactive mixtures into a single carrier—to broaden functionality and lower effective dosages. Scope and approach: Unlike preceding reviews that predominantly focus on single-oil encapsulation, this article addresses the critical knowledge gap regarding the physicochemical and functional synergies unique to multi-component systems. We critically synthesize the state-of-the-art to move beyond fabrication techniques, evaluating how blending affects colloidal stability, elucidating the “multi-hit” molecular mechanisms against multidrug-resistant pathogens, and analyzing the complex release kinetics characteristic of binary-loaded systems. Key findings: Unique to co-encapsulated systems, specific oil combinations significantly enhance stability by optimizing surface charge. Mechanistically, these systems generate synergistic lethality unattainable by mono-delivery: the carrier facilitates the synchronized arrival of a membrane-permeabilizer and an intracellular metabolic inhibitor, resulting in the simultaneous downregulation of virulence genes and biofilm eradication at fractional doses. Furthermore, kinetic modeling reveals a competitive release phenomenon, where molecular discrimination within the carrier matrix allows for the sequential, rather than simultaneous, release of volatiles, enabling prolonged, multi-stage preservation. Conclusions: Co-encapsulation transforms volatile metabolites into intelligent, multi-functional delivery systems that overcome the sensory and efficacy ceilings of single-oil formulations. Future research must address the “scale-up paradox” between fabrication precision and throughput, develop predictive models for multi-component diffusion, advance multi-component co-encapsulation systems—particularly for biological applications—and rigorously establish nanotoxicological safety profiles for these complex ternary systems.