Student Research Projects

Efficiency of supercritical fluid extraction of essential oils from celery and dill seed at varying temperatures and pressures.

Student Tone' Boykins, '17
Faculty Mentor(s)
Department Chemistry
Course CHEM 489: Research in Natural Sciences


Supercritical fluid extraction (SFE) is a relatively new and more environmentally friendly method than traditional methods, such as steam distillation and solvent extraction. The essential oils in spices are a very small percentage of the total mass and typically require a large amount of organic solvents in their isolation. In this study, the effect of pressure and temperature on the efficiency of extraction in the isolation of essential oils by supercritical fluid was investigated. The first set of trials were ran to understand the effect of pressure on the extraction method. Dill and celery seeds were freshly ground and subjected to SFE at various temperatures (40-80 degrees C) and various pressures (4000-8000 psi) to isolate the essential oils, which were subsequently stored at room temperature in the dark. The optimal conditions for extraction of the dill seed was determined to be 6000 psi and 40 degrees C, whereas the optimal conditions for the extraction of celery seed was determined to be 6000 psi and 80 degrees C. The components of the essential oils that were isolated from dill and celery seeds were compared to the essential oils extracted via steam distillation followed by solvent extraction. The dill extracts from both SFE and steam distillation yielded four major components, that were identified as apiol, carvone, trans-dihydrocarvone, and limonene. Three of these components (apiol, carvone, and limonene) have previously been identified as major components of dill seed oil. On the other hand, the celery extracts from both SFE and steam distillation yielded five major components, that were identified as limonene, ?-Selinene, 3-butylphthalide, ?-Selinene and 2-Naphthalenemethanol. The first three components listed have been previously identified as major components of celery seed oil. Since the essential oils isolated by SFE have similar composition to the oils isolated by steam distillation, and at much higher yields, SFE is a more efficient and greener isolation method for essential oils.