Optimization and characterization of 1,8-cineole/hydroxypropyl-β-cyclodextrin inclusion complex and study of its release kinetics

Essential oils can be capsulated by cyclodextrin to enhance its thermal stability and preserve the bioactivity. In this study, 1,8-cineole was used as a guest molecule to prepare the cyclodextrin inclusion complexes (ICs). The formulation and processing parameters were optimized using the response surface methodology (RSM), and the optimal conditions were identified to be: 2.30 h of encapsulating time, 30.1 °C of encapsulating temperature and 0.99 of molar ratio of 1,8-cineole to HP-β-CD. The corresponding encapsulation efficiency and loading efficiency were 83.17% and 8.40%, respectively. The produced 1,8-cineole/HP-β-CD ICs was characterized by SEM, FTIR and TGA, and the results proved the enhanced thermal stability of IC. The release behavior and kinetics of IC was investigated and showed that at elevated temperature and relative humidity, the releasing rate of 1,8-cineole from the ICs increased and followed the Fick's law.