Extraction of Essential Oils - Need of the Hour

Essential oils are composed of a wide range of bioactive chemical compounds. These are volatile oils distilled from aromatic plant materials. The Indian essential oil industry manufactures rose, kewda, lemon grass oil, peppermint oil, oil of champa, citrus oil, palmarosa, mentha and celery oils. The extraction of highly delicate essential oils from plants remains a crucial step in all these applications. Different methods can be used for that purpose, e.g. hydro-distillation (HD), steam distillation and Solvent extraction. Losses of some volatile compounds, low extraction efficiency, degradation of unsaturated or ester compounds through thermal or hydrolytic effects and toxic solvent residue in the extract may be encountered using these extraction methods. These shortcomings have led to the consideration of the use of new innovative technique in essential oil extraction, which typically use less solvent and energy, such as supercritical fluids and microwave assisted extraction. Super critical fluid extraction has become a valid alternative, mainly, because the dissolving power of the extracting medium can be adjusted by regulating the pressure and temperature conditions. Solvent-free microwave extraction (SFME), a combination of microwave heating and dry distillation, is a newly developed technique.