Food-Grade Colloidal Systems for the Delivery of Essential Oils

This review presents a critical analysis of food-grade delivery systems, which are suitable for the delivery of essential oils (EOs) for food applications. In particular, the main colloidal systems, investigated in vitro for the encapsulation of essential oils, such as nanoemulsions, solid lipid nanoparticles, nanostructured lipid carriers, carbohydrate-based carriers, protein-based carriers, liposomes and gelatin, have been described in details, with a special focus on their formulation, the type of oils encapsulated, and the fabrication processes, as well as on the resulting antimicrobial activity with respect to free oils. Currently, among these food-grade colloidal systems, only nanoemulsions, liposomes, and biopolymeric particles have found use in real foods, because of their easily-scalable production processes, loading capability with EOs, as well as cost-effectiveness. The main applications in foods are discussed, with reference to the possible methods of incorporation of encapsulated essential oils in foods, such as direct mixing, washing or infusion, and coating within active biopolymeric matrices. In addition, also the use of encapsulated essential oils in several other fields is presented, such as in organic farming, pest control or luring, as well as in pest-repellent textiles. Finally, the main regulatory issues are discussed.