Inclusion complex of turmeric essential oil with hydroxypropyl-β-cyclodextrin: Preparation, characterization and release kinetics

The application of turmeric essential oil (TEO), a natural effective antibacterial agent, in food preservation is limited due to high volatility and low stability. This study aimed to improve its stability and release behavior by synthesizing TEO/hydroxypropyl-β-cyclodextrin (HP-β-CD) inclusion complex (IC) in a saturated aqueous solution. An orthogonal experimental design was used to determine the optimal process conditions (HP-β-CD to TEO, g/mL), 16:1; stirring speed, 850 r/min; encapsulation time, 2 h), achieving a comprehensive score value of 85.62% for TEO/HP-β-CD-IC. Through comprehensive characterization, the results showed that TEO was completely embedded in HP-β-CD with increased stability. Free TEO exhibited a weight loss of 67.64% between 30 and 300 °C, while TEO/HP-β-CD-IC had a mass loss of only 9.33%. HP-β-CD and TEO/HP-β-CD-IC showed positive ZP values that were 124.76 mV and 132.16 mV, respectively. The release behavior and release kinetics of TEO/HP-β-CD-ICs were also studied, and the results showed that TEO/HP-β-CD-IC release rate increased under higher temperature and relative humidity-consistent with Fick's diffusion.