Characterization of Key Odorants in Cumberland Rosemary, <i>Conradina verticillata</i>
Claire Gorman, Anne F. Murray, Melissa Dein, John P. Munafo
Abstract
Conradina verticillata Jennison, commonly known as Cumberland Rosemary, is an endangered plant from the mint family Lamiaceae. This species is a flowering, perennial shrub found only in a few counties in Kentucky and Tennessee. Although the odorants responsible for Cumberland Rosemary’s unique aroma have not been previously characterized, in this study, a total of 32 odorants were identified using gas chromatography–olfactometry (GC–O) and gas chromatography–mass spectrometry (GC–MS). Odorant flavor dilution (FD) factors were determined through the application of aroma extract dilution analysis (AEDA). Seven odorants with FD factors ≥64 were quantitated by stable isotope dilution assays (SIDA), and their odor activity values (OAV) were calculated. Odorants with OAV ≥1 included 1-octen-3-one (earthy-mushroom, OAV 2,900,000), 1,8-cineole (eucalyptus, OAV 510,000), borneol (earthy, OAV 10,000), bornyl acetate (earthy-fruity, OAV 3,700), eugenol (spicy, OAV 2,200), menthone (mint, OAV 130), and camphor (herbaceous, OAV 72). Sensory analysis revealed that an odor simulation model based on the quantitative data was a close match to the aroma of the plant. Omission studies determined that 1-octen-3-one, 1,8-cineole, and eugenol were the key odorants critical to Cumberland Rosemary’s distinct aroma profile. The stereochemistry of selected odorants was also determined by chiral chromatography. This study established a foundation for future experiments on the aroma chemistry of C. verticillata and the other six members of the Conradina genus.