CO2-supercritical extraction, hydrodistillation and steam distillation of essential oil of rosemary (Rosmarinus officinalis)

Essential oil of rosemary was obtained by supercritical CO2-extraction (SCE), hydrodistillation (HYDRO), and steam distillation (SD). Quantity of oil, antioxidant activity, and chemical composition (gas chromatography-mass spectrometry, GC-MS) of the essential oils were evaluated. For SCE, oil was obtained at two temperatures (40 and 50 °C) and two pressures (10.34 and 17.24 MPa) using a rosemary particle size of 600 ± 50 μm. The yield was between 1.41 and 2.53 g essential oil (EO) 100 g−1 of dry rosemary (% w/w). The antioxidant activity values were in the range 29.67-37.55 mg equivalent of Trolox (ET) g−1 of EO or 22.66-30.81 mg ascorbic acid (AA) g−1 of EO. Yields of essential oil were between 0.35 and 2.35%. The antioxidant activity was found in the range 1.73-2.60 mg ET g−1 of EO or 1.50-2.20 mg AA g−1 of EO. Camphor, eucalyptol, β-caryophyllene, and borneol acetate were the main chemicals detected by GC-MS in EO.