Encapsulation of Natural Flavors in Cyclodextrins: Free Volume Studies by PALS
Positron annihilation lifetime spectroscopy (PALS) is used to study the free-volume in β-cyclodextrin (CD) with the encapsulation of two different essential oils: garlic (Allium sativum) and marjoram (Origanum majorana). The data reveal the presence of a long lifetime component related to the o-Ps. It is observed that the addition of garlic (or marjoram) oil to β-CD results in a decrease of the o-Ps lifetime which was ascribed to a reduction of the free volume holes from 83.6 to 67.7 Å3 (79.1 to 72.6 Å3). Different mechanisms for the encapsulation of garlic and marjoram oils in β-CD are suggested by the PALS parameters.
Jozef Krištiak, Jan Kuriplach and Pradeep K. Pujari
M. F. Ferreira Marques et al., "Encapsulation of Natural Flavors in Cyclodextrins: Free Volume Studies by PALS", Materials Science Forum, Vol. 733, pp. 88-91, 2013