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

Abstract

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 condition s . The aim of this study was to enhance thermal stability and antioxidant activity of T hyme essential O il (TO) by encapsulation in C hitosan N anoparticles (CS - NP). TO was encapsulated in CS - NP with an emulsion – ionic gelation crosslinking method and the constru ction was confirmed by Fourier T ransform I nfrared spectroscopy (FT - IR) and thermogravimetric analysis techniques. The effect of CS: TO weight ratio encapsulation efficiency, loading capacity, particle size and zeta potent ial of TO - loaded C hitosan N anoparticle (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, w hen TO was encapsula ted in CS - NP, antioxidant activity proved to be superior from that of free TO. The considerable antioxidant activity and thermal stability reveal that such particle s have promising application for delivery of TO in medicine, food and feed. Keywords: Antio xidant activity, Chitosan nanoparticle, Encapsulation, Thermal stability , Thyme oil.