Supercritical fluid extraction of volatile compounds from lavandin and thyme

Supercritical fluid extraction (SFE) of lavandin flowers and thyme herb using carbon dioxide was carried out under different extraction conditions. A stepwise increase of the extraction pressure resulted in the fractionation of the extracts into liquid and pasty products. Investigations on other ways of fractionation of the extracts were conducted, such as a single extraction and release of carbon dioxide at two stages by using two separators in series to effect the separation of the dissolved components. The SFE products were compared with essential oils obtained by conventional steam distillation. In the case of lavandin flowers, SFE products were found to be markedly different from the corresponding steam distilled oil. A remarkable amount of α-terpineol was present, and the ratio of linalol to linalyl acetate was extremely high in the steam-distilled essential oil in comparison with the supercritical fluid extract, which resulted from the hydrolysis of components during steam distillation. SFE of thyme gave a product which contained 10-15% thymol and 30-35% carvacrol, while steam distillation produced an oil containing 48-50% thymol and only 8-10% carvacrol. When the SFE products were collected as separate samples successively in time, marked changes were observed in the composition of the samples as the extraction progressed. Supercritical fluid extraction (SFE) of lavandin flowers and thyme herb using carbon dioxide was carried out under different extraction conditions. A stepwise increase of the extraction pressure resulted in the fractionation of the extracts into liquid and pasty products. Investigations on other ways of fractionation of the extracts were conducted, such as a single extraction and release of carbon dioxide at two stages by using two separators in series to effect the separation of the dissolved components. The SFE products were compared with essential oils obtained by conventional steam distillation. In the case of lavandin flowers, SFE products were found to be markedly different from the corresponding steam distilled oil. A remarkable amount of α-terpineol was present, and the ratio of linalol to linalyl acetate was extremely high in the steam-distilled essential oil in comparison with the supercritical fluid extract, which resulted from the hydrolysis of components during steam distillation. SFE of thyme gave a product which contained 10-15% thymol and 30-35% carvacrol, while steam distillation produced an oil containing 48-50% thymol and only 8-10% carvacrol. When the SFE products were collected as separate samples successively in time, marked changes were observed in the composition of the samples as the extraction progressed.