Release characteristics of freeze-dried eugenol encapsulated with beta-cyclodextrin by molecular inclusion method

The study investigated the thermo-physical properties of eugenol encapsulated with beta-cyclodextrin (beta-CD) by molecular inclusion and eugenol release characteristics at various relative humidities and storage temperatures. Particle size, Zeta-potential, thermal transition and morphology of beta-CD-Eugenol complex after freeze-drying measured using Nanosizer, differential scanning calorimeter (DSC) and transmission electron microscopy (TEM), respectively. The particle size, Zeta-potential and inclusion efficiency of encapsulated eugenol presented approximately 340 nm, -34.5 mV and 91.7% after freeze-drying, respectively. The relationship between retention rate of eugenol and time during release was described by a mathematical model of Avrami equation. In these events, the parameter of release mechanism and the release rate constant were rapidly elevated with increasing relative humidity and storage temperature. Furthermore, the Arrhenius activation energy for the release of eugenol decreases with increasing relative humidity and storage temperature.