Powdery Encapsulation of d-Limonene by Kneading with Mixed Powders ofβ-Cyclodextrin and Maltodextrin at Low Water Content

To enhance the storage stability of essential oils such as d-limonene, a mixed powder of β-cyclodextrin and maltodextrin was used to encapsulate the liquid flavor in a powder state. In this study, powdery encapsulation of d-limonene was done by direct kneading of d-limonene with the mixed powder at low water content, using a twin screw kneader. The retention of d-limonene in the periodically sampled powder reached a maximum when the mass ratio of β-cyclodextrin to maltodextrin in the mixed powder equaled unity and the initial molar ratio of d-limonene to β-cyclodextrin was larger than unity. From X-ray diffraction of the powder, it could be guessed that the maximum retention of d-limonene might come from the adsorption of d-limonene upon maltodextrin. The equilibrium retention of d-limonene in the dry powder depended not only upon the mass ratio of β-cyclodextrin to maltodextrin in the mixed powder, but upon the initial moisture content in the powder. The equilibrium retention could be estimated well by a simple calculation.