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

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.