Dehydration of CO₂-α-cyclodextrin complex powder by desiccant adsorption method and its release properties

Abstract

Stability and release properties of CO₂-α-cyclodextrin complex powder prepared by solid encapsulation (water activity, a_w ≈ 0.95) followed by moisture removal using silica gel and CaCl₂ desiccants during post-dehydration were investigated. The results showed that CaCl₂ reduced a_w much faster than silica gel did under the same conditions. After approximately 60 h, a_w of complex powders reduced using silica gel was almost constant at 0.247 (±0.012), while those treated with CaCl₂, a_w was 0.225 (±0.005) and had not yet reached their lowest value. Moisture adsorption by silica gel and CaCl₂ also led to a decrease in the CO₂ concentration of complex powder (higher decrease for silica gel adsorption) without affecting the structure and morphology of complex powder. The CO₂ release properties of CaCl₂-a_w-reduced complex powder at different relative humidities (32.73, 52.86, 75.32 and 97.30% RH), liquid environments (water and oil) and packaging methods (normal and vacuum) were also studied.

Keywords:

• Release properties
• relative humidity
• complex powder
• amorphous α-CD powder
• solid encapsulation

Acknowledgements

The authors acknowledge the facilities, and the scientific and technical assistance, of the Australian Microscopy and Microanalysis Research Facility (CMM), SAFS, CNAFS and CAI centres at The University of Queensland. Special thanks to Dr. Ekaterina Strounina (CAI) for NMR measurement, to Dr. Anya Yago (CMM) for X-ray analyses. Thao M. Ho also acknowledges financial support from Australia Awards Scholarships.

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.