Study on host-guest interaction of aroma compounds/γ-cyclodextrin inclusion complexes

Abstract

The hydrophobic cavity of cyclodextrin (CD) embeds aroma compounds and forms inclusion complexes (ICs). However, the possible inclusion and stabilization mechanisms remain unclear. In this study, ICs of γ-cyclodextrin (γ-CD) and 13 aroma compounds (alcohols, aldehydes, and alkenes) were prepared and characterized using Fourier transform infrared spectroscopy, X-ray diffraction, and nuclear magnetic resonance. Moreover, molecular dynamics simulation (MD) also simulated the possible complex formation, listed the interactions between the aromatic compounds and γ-CD, and explored the host-guest interaction and stabilization mechanisms. The results showed that the characteristic peaks of the aroma compounds weakened or even disappeared after inclusion, with all the ICs being crystalline. Eight aroma compounds formed ICs at a host-guest molar ratio of 1:1, while at 1:2 for the remaining compounds. The benzene ring of the aroma compounds was more likely to enter the hydrophobic cavity; the methyl group and double bond of α-terpineol entered the cavity preferentially. MD analysis revealed that for guests with similar molecular weights, the intermolecular interactions followed the following trend: alcohols > aldehydes, alkenes > aldehydes; for the same functional group distribution and unsaturation, the interaction force being positively correlated with molecular weight. The present study aimed to provide a theoretical basis for aroma embedding systems’ stable and controllable preparation.