Advances in the application of interfacial engineering approaches on the encapsulation, release, and bioaccessibility of carotenoids

Carotenoids are valuable hydrophobic nutraceuticals with established health benefits, yet their application is constrained by poor aqueous solubility, chemical instability, and low gastrointestinal bioaccessibility. Although multiple reviews have summarized colloidal delivery systems for carotenoid encapsulation, they rarely elucidate how interfacial architecture mechanistically governs digestion, micellization, and absorption, thereby limiting rational design. This review critically synthesizes recent progress in interfacial engineering of carotenoid-loaded colloidal systems, integrating evidence across simple, particle-stabilized, composite, and multilayer interfaces. We systematically analyze how interfacial composition, thickness, charge and permeability regulate lipid hydrolysis kinetics, enzyme accessibility, interfacial remodeling, and mixed-micelle formation, and how these processes collectively determine carotenoid release and bioaccessibility. Rather than descriptive comparisons, a conceptual framework is proposed to connect specific interfacial strategies with programmable delivery behaviors, highlighting inherent tradeoffs between physical stability and digestive responsiveness. In addition, limitations of in vitro digestion models, the scarcity of in vivo validation, feasibility in real food matrices, regulatory considerations, and scale-up challenges are critically discussed. Future research priorities are outlined, including advanced dynamic digestion models, structure-bioaccessibility mapping, and translational validation. This review aims to provide mechanistic insight and actionable design guidance for next-generation carotenoid delivery systems.