Eugenol-loaded chitosan nanoparticles: I. Thermal stability improvement of eugenol through encapsulation

The objective of the present work was to improve the thermal stability of eugenol by encapsulating into chitosan nanoparticles via an emulsion–ionic gelation crosslinking method. The influences of the initial eugenol content and tripolyphosphate (TPP) concentration on the loading capacity (LC), encapsulation efficiency (EE), morphology and surface charge of the eugenol-loaded chitosan nanoparticles were also investigated. LC and EE tended to increase with increasing initial eugenol content and decreasing TPP concentration. Particles with LC of 12% and EE of 20% exhibited a spherical shape with an average size of less than 100 nm. Thermal stability of the encapsulated eugenol was verified through its extrusion at 155 °C with a model plastic, i.e. thermoplastic flour (TPF). TPF containing encapsulated eugenol showed 8-fold higher remaining eugenol content and 2.7-fold greater radical scavenging activity than that containing naked eugenol. The results suggest the possible use of eugenol-loaded chitosan nanoparticles as antioxidants in bioactive plastics for food packaging.