Application of γ-cyclodextrin encapsulation of eugenol and isoeugenol: characterization, stability, and taste impact

Eugenol and isoeugenol, key flavor isomers, exert distinct effects on sweetness perception but suffer from poor thermal and oxidative stability, as well as rapid aroma volatilization, during food processing and storage. γ-Cyclodextrin (γ-CD) ameliorates these drawbacks via host-guest inclusion; however, the structural differences of their inclusion complexes and the T1R2/T1R3-mediated sweetness regulation mechanism remain elusive, limiting their applications in sugar-reduced food formulations.

This study aimed to comprehensively characterize γ-CD inclusion complexes of eugenol and isoeugenol, elucidate their differential sweetness regulation via T1R2/T1R3 at molecular and sensory levels, and reveal structural-stability relationships, hypothesizing that cis-trans isomeric differences (eugenol: cis-double bond; isoeugenol: trans-double bond) drive distinct complex properties and sweetness effects.

Complexes were prepared via the solvent-dropping method (optimized with 1:2 M ratio, 60 °C, 7 h). XRD, DSC, TGA, FTIR, and ¹H NMR characterized structures; molecular docking and MD simulation analyzed molecular interactions; sensory evaluation coupled with an electronic tongue assessed sweetness regulation in 5 % sucrose solution.

XRD, FTIR, and ¹H NMR confirmed successful inclusion by revealing characteristic structural changes (e.g., XRD peak shifts, FTIR band masking). The eugenol complex (126 °C endothermic peak) shows better thermal stability than the isoeugenol complex (95 °C), with both delaying aroma volatilization. The isoeugenol complex has lower T1R2/T1R3 binding energy (-9.841 kcal/mol) than eugenol (-9.518 kcal/mol). Eugenol enhanced sweetness (≤7 mg/L); isoeugenol inhibited it (≥0.1 mg/L), with inhibition alleviated by heating.

γ-CD encapsulation enhances eugenol/isoeugenol stability and sustained aroma release. Isomeric differences lead to distinct T1R2/T1R3 binding modes and differential sweetness regulation, providing theoretical and technical support for precise flavor-sweetness control in sugar-reduced foods and laying a foundation for their practical integration into low-sugar food systems.