Encapsulation of Essential Oils via Spray Drying: Recent Developments in Wall Materials, Emulsion Technologies, and Food Applications

The encapsulation of essential oils represents a promising strategy to overcome their inherent volatility, chemical instability and limited water solubility, which limit their wider application in food and nutraceutical products. This review provides a compre-hensive examination of recent advances in wall materials and emulsion technologies used for the microencapsulation of essential oils by spray drying. Traditional wall ma-terials such as maltodextrin, gum arabic and whey protein isolates have been exten-sively studied; however, novel biopolymers have proven to be effective alternatives that allow for improved encapsulation efficiency and controlled release. Improved emulsion stability can be achieved by high pressure homogenisation and ultrasonic treatment. They have facilitated the production of stable emulsions with a uniform droplet size distribution, which is crucial for efficient encapsulation. Nanoemulsions and Pickering emulsions have great potential to produce very stable microcapsules with essential oils compared to conventional emulsions. Advances in spray drying technology, such as electrostatic spray drying and nanospray drying, have further im-proved the bioavailability of essential oils and optimised the release kinetics. The ap-plications of spray-dried essential oils have shown significant potential for extending shelf life, reducing synthetic additives and improving flavour in various foods, as well as for the development of functional food supplements. Future research should focus on process optimisation, scalability and evaluation of release behaviour under real stor-age and consumption conditions.