ON 12 A study of essential oil extraction and antioxidant activity of patchouli ( Pogostemon cablin ) using supercritical carbon dioxide

This study investigates the extraction of patchouli oil using supercritical carbon dioxide (SCCO2). The patchouli plants utilized in this study were obtained from Indonesia. The effect of pressure on yield, antioxidant activity and total phenolic content of the extracts was investigated at operating pressures ranging from 100 – 200 bar. The extract yield, antioxidant activity (evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay) and total phenolic content were compared against conventional steam distillation. SC-CO2 extraction obtained extract yields and total phenols in the range of 3.41 to 3.95% and 1.869 to 2.756 mg GAE/g respectively, which were higher than steam distillation (1.13% and 1.677 mg GAE/g). Furthermore, the SC-CO2 extracts exhibited IC50 (effective concentration to reduce 50% of DPPH free radicals) values in the range of 0.581 mg/ml to 1.538 mg/ml, which were better than the IC50 value exhibited by steam distilled patchouli oil (> 4 mg/ml). Introduction Pogostemon cablin (patchouli) is an aromatic herb that is extensively cultivated in Brazil, China and Indonesia for its essential oil. The essential oil of patchouli plant is known to have great business potential in the international market due to its unique flavour, fragrance and biological activities [1]. In the perfumes and cosmetics industry, patchouli oil is a vital ingredient in exotic perfumes offering a rich and spicy fragrance. Its fixative properties provides a strong lasting character to perfumes when blended with other essential oils. It is also used as a perfume in its own right [2]. Furthermore, the fixative properties of patchouli oil assists in limiting evaporation and promoting firmness, allowing it to be valuable in the manufacturing of soaps, scents, body lotions and detergents. In aromatherapy, it is used to soothe nerves, control appetite, and relieve depression and stress. Moreover, patchouli oil is on the FDA's (Food and Drug Administration) list of substances approved for human consumption as a natural additive for food flavouring [3]. In food industries, patchouli oil is extensively used as a flavour ingredient in major food products including alcoholic and non-alcoholic beverages [4]. Very low concentration (2 mg/kg) of this oil is used to flavour foods, beverages, candy and