Integration of electronic nose and comprehensive two-dimensional gas chromatography-olfactometry-time-of-flight mass spectrometry to decode the olfactory quality enhancement of agarwood essential oil upon thermal treatment.

Agarwood essential oil is highly valued for its elegant scent profile; however, its fresh state is often accompanied by off-odors, limiting its direct application. Traditional aging requires months to mitigate off-odors, making it unsuitable for large-scale production. To address this challenge, this study employed thermal treatment as an innovative method to rapidly age the oil as an alternative. The results show that thermal treatment eliminates off-odors with comparable efficacy to six months of traditional aging, while enhancing the overall odor with stronger sweet and woody notes to achieve a more layered scent. For objective evaluation, an electronic nose (E-Nose) technology combined with comprehensive two-dimensional gas chromatography-olfactometry-time-of-flight mass spectrometry (GC × GC-O-TOF-MS) was employed. Multivariate analyses (PCA, OPLS-DA, etc.) distinguished sample odor fingerprints and indicated odor optimization. Further GC × GC-O-TOF-MS analysis identified 11 key sesquiterpenes that contribute to scent enhancement. Molecular docking simulations explored their interactions with olfactory receptors (ORs), establishing a structure-activity relationship that tentatively interprets their olfactory contribution, specifically through hydrogen bonds, van der Waals forces, and hydrophobic interactions, which may contribute to the boosted sweet and woody notes. The thermal method rapidly improves essential oil quality and demonstrates the utility of GC × GC‑O‑TOF‑MS in analyzing complex odor‑active compounds.