Current progress in microencapsulation of spice essential oils: Bridging conventional and novel approaches for improved stability, controlled release, and bioactivity preservation

Essential oils derived from spices are known for their bioactive properties. However, their application is restricted due to volatility of their bioactive substances, which are sensitive to environmental factors such as light, oxygen, and temperature. Microencapsulation is used for protecting essential oils, increasing their stability, and enhancing their functionality. Various methods of encapsulation such as, spray drying, freeze drying, complex coacervation, fluidized bed coating, supercritical fluids, Pickering emulsions, molecular inclusion, and millifluidic are critically compared in this review based on encapsulation performance, release behaviour, stability, cost, scalability, and industrial applicability. Important characterisation methods, common release-kinetic models, and the physicochemical mechanisms controlling encapsulation and release are also covered. Lastly, artificial intelligence, computational modelling, stimuli-responsive and hybrid delivery systems, and sustainable manufacturing are discussed. This review provides a concise framework for advancing efficient, scalable, and application-oriented encapsulation systems for spice essential oils.