Comprehensive analysis of volatile compounds in hybrid sweetgum population and other Liquidambar species by HS-SPME-GC-MS.

Background: Liquidambar species are rich sources of essential oils, with applications in cosmetics, perfumes, and pharmaceuticals. Traditionally, the industrial utilization of Liquidambar essential oil has focused on extraction from the resin, while the full potential of their leaf-derived essential oils remains underexplored. This study systematically compares the essential oil composition, sensory characteristics, and aroma profiles of leaves from various Liquidambar species, including hybrid sweetgum, using headspace solid-phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS). A precise internal standard method was conducted to identify progenies exhibiting heterosis in volatile content from a hybrid sweetgum population of 110 full-sib progenies.

Results: A total of 44 volatile compounds were identified, with monoterpenes (α-pinene, β-pinene, d-limonene) dominating Liquidambar styraciflua, Liquidambar formosana and hybrid sweetgum, while Liquidambar orientalis exhibited a unique d-Camphene-rich profile. Hybrid sweetgum progenies exhibiting heterosis in essential oil content were found, with several progenies significantly exceeding the average level. Sensory analysis, combined with odor activity value (OAV) calculations, revealed species-specific aroma profiles: L. styraciflua and hybrid sweetgum were characterized by citrus/herbaceous notes (high d-limonene OAV = 11.07), whereas L. orientalis exhibited pungent camphoraceous tones (d-camphene OAV = 15.9). Multivariate analyses identified eight key volatile compounds with high variable influence on projection (VIP > 1).

Conclusions: This study highlights the hybrid sweetgum population as a promising genetic resource for high essential oil yield, with seven elite progenies showing industrial potential. The distinct volatile profiles of Liquidambar species, particularly the d-camphene dominance in L. orientalis, underscore genus-wide metabolic diversity.