Volatile oils, also known as essential oils, are aromatic oily liquids obtained from plant materials. They are called volatile because they evaporate easily at normal temperatures, releasing their fragrance. These oils are widely used in perfumery, aromatherapy, flavoring, and traditional medicine.


General Methods for Extraction of Volatile Oils

  1. Steam Distillation:

    • Process: Plant materials are subjected to steam, which causes the essential oils to evaporate. The steam carrying the volatile compounds is then condensed back into liquid form, and the oil is separated from the water.
    • Application: Most commonly used method for extracting essential oils from flowers, leaves, and stems.

  2. Hydrodistillation:

    • Process: Plant materials are immersed in water and heated. The water and oil vapors are condensed, and the oil is separated from the water.
    • Application: Suitable for materials that can withstand direct contact with boiling water without degrading.

  3. Solvent Extraction:

    • Process: A solvent (usually hexane or ethanol) is used to dissolve the essential oil from the plant material. The solvent is then evaporated, leaving behind the essential oil.
    • Application: Used for delicate plant materials that might be damaged by heat, such as jasmine and tuberose.

  4. Cold Pressing:

    • Process: Plant materials, particularly citrus peels, are mechanically pressed to release the oil.
    • Application: Commonly used for citrus fruits like oranges, lemons, and limes.

  5. Supercritical Fluid Extraction (SFE):

    • Process: Carbon dioxide is used at high pressure and low temperature to extract the essential oils. Once the extraction is complete, the pressure is reduced, and the CO₂ returns to a gaseous state, leaving behind the essential oil.
    • Application: Produces high-quality essential oils with minimal residue.

  6. Enfleurage:

    • Process: Delicate flowers are placed on trays coated with a layer of fat, which absorbs the essential oils. The fat is then washed with alcohol to extract the oils.
    • Application: Traditional method used for flowers with very delicate scents, such as jasmine and tuberose.

  7. Microwave-Assisted Extraction:

    • Process: Microwave radiation is used to heat the plant material and release the essential oils. The microwave energy causes water in the plant cells to evaporate, rupturing the cell walls and releasing the oils.
    • Application: An emerging technique that can be faster and more efficient than traditional methods.

Each method has its advantages and is selected based on the type of plant material and the desired quality of the essential oil.