Enhancement of Thermal Stability and Antioxidant Activity of Thyme Essential Oil by Encapsulation in Chitosan Nanoparticles

The use of essential oils as the preservative agents in food industry faces the problem of interactions with food matrix components, low solubility in aqueous phase, high volatile character and sensitivity to environmental conditions. The aim of this study was to enhance thermal stability and antioxidant activity of Thyme essential Oil (TO) by encapsulation in Chitosan Nanoparticles (CS-NP). TO was encapsulated in CS-NP with an emulsion–ionic gelation crosslinking method and the construction was confirmed by Fourier Transform Infrared spectroscopy (FT-IR) and thermogravimetric analysis techniques. The effect of CS: TO weight ratio encapsulation efficiency, loading capacity, particle size and zeta potential of TO-loaded Chitosan Nanoparticle (CS-NP-TO) were investigated. The encapsulated TO was decomposed at a higher temperature (318-325.4ºC) than free TO (170ºC) reflecting the enhanced thermal stability of TO by encapsulation. Also, when TO was encapsulated in CS-NP, antioxidant activity proved to be superior from that of free TO. The considerable antioxidant activity and thermal stability reveal that such particles have promising application for delivery of TO in medicine, food and feed.