Objective Compositions, odor characteristics, sources and release mechanisms of volatile organic compounds (VOCs) from Eucalyptus grandis × E. urophylla woods were clarified in this paper. It could provide reference for the scientific utilization of wood.
Method Chemical components, odor characteristics and odor intensity of VOCs released from heartwood and sapwood with different moisture contents were detected via gas chromatography-mass spectrometry-olfactometry (GC-MS-O).
Result In total, 41 substances were successfully identified. Among them, 13 species were odor-active compounds. The main odorants were eucalyptol, camphor and camphene. Terpenoid odorants emitted from sapwood and heartwood were significantly different, such as borneol and γ-terpinen only detected from heartwood. Terpenoids, aldehydes, hydrocarbons and alcohols composing odor-active compounds emitted from E. grandis × E. urophylla woods were dramatically impacted by wood moisture content. With the decrease in moisture content, the total mass concentrations of odor-active compounds released from sapwood decreased in general, while those released from heartwood firstly increased and then decreased. In all the components, the concentrations of terpenoids and aldehydes had significant changes under the influence of sapwood moisture content, and that was terpenoids and alcohols for heartwood. When wood moisture contents were higher than 30%, the amount of odorants from heartwood was significantly higher than sapwood, and it was in the opposite direction at 10%−30% moisture contents. Terpenoids were the most component of odorants, showing smell of camphor and pine aroma. Aldehydes were the second largest component and contributed mainly to fruit flavor. The odour attributes of E. grandis × E. urophylla timber were mainly camphor and fruit aromas, accompanied by sweet fragrance, almond oil aroma, pine aroma, leather aroma and other scents. With the decrease of moisture content, the odor intensity of odorants form sapwood and heartwood increased at first and then decreased. The fruit flavor fluctuated most significantly for sapwood, whereas the camphor flavor was for heartwood when moisture contents were changed. Compared with the fresh eucalyptus with a strong camphor flavor, camphor odor intensity was reduced and together with the fruit flavor after wood drying treatment.
Conclusion Abundant terpenoids emitted from E. grandis × E. urophylla woods are beneficial to sterilization, anti-inflammation and health. These odors from well-seasoned wood could make residents feel relaxed and freshened. Therefore, E. grandis × E. urophylla wood is suitable for application in the indoor and rehabilitation landscapes.