Comparative investigation of key aroma terpenoids of Litsea cubeba essential oil by sensory, chromatographic, spectral and molecular studies

Litsea cubeba essential oil (LcEO) is a natural product extracted form L. cueba fruits. LcEO is widely used for flavoring in Chinese cooking and provides diverse aromas from different chemotypes, but their characteristic flavor and odorants determining the usage remain unknown. In this study, LcEOs were extracted from three chemotypes L. cubeba fruits by hydrodistillation for 4 h, the liquid to material ratio is 20:1 (mL.g(-1)) and comprehensively investigated at the sensorial, spectral and molecular levels. Twenty-seven crucial odorants in the LcEOs were quantified using gas chromatography-olfactometry/mass spectrometry (GC-O/MS), and ten odorants with odor activity value (OAV) > 1 were further confirmed, particularly geranial (57917.84), neral (41932.79), beta-pinene (4041.23), beta-myrcene (1936.86), citronellal (2215.11), terpinen-4-ol (233.97) and 1,8-cineole (7573.95) were identified as the potential odor-active markers. The aroma-spectral/gene expression network elucidated the aroma variation by determining the differential expression pattern of the terpene synthase (TPS) gene LcTPS22. And spectrum bands at 1635 nm, 1902 nm, 2125 nm, 2220 nm and 2250 nm contributed to the variation in the LcEOs. Comparative investigation of the characteristic flavor of LcEOs will significantly expand our knowledge of L. cubeba aroma, provide new insights into LcEO utilization and improve the direct breeding of L. cubeba.