There are various methods being
employed these days for extracting essential oils from different spices
and herbs. The quality of oil extracted depends on the kind of method
used for extracting oil. Below are few of the major extraction methods
being used these days:
- Steam Distillation : One of the most popular method for
extracting oil from spices, the process involves heating the water
to produce steam, which is a carrier of volatile chemicals present
in the spice. An outside source of steam is used, which is
introduced into the distillation unit at a high pressure. The steam
is finally condensed and the resulting essential oil is collected
separately.
- Hydrodistillation : This is one of the oldest methods of
extraction used. The spice is fully immersed in hot water. The
result is a soup, which carries aromatic molecules of the plant. The
method is not much in use these days, because of the risk of over
heating the plant and subsequent loss of the oil. The method is best
suitable for spice in dry and powdered form of roots and barks.
- Solvent Extraction : Many herbs and spices cannot be
extracted from distillation method, so solvent extraction is the
safest method for extracting high quality oil. Spices or herbs to be
extracted are washed with a solvent, which dissolves all extractable
matter from the plant. These include pigments, volatile molecules
and non-aromatic waxes. The herbs and spices are then subjected to
low pressure distillation and the volatile oil is then separately
collected.
- Carbon Dioxide Extraction : This method is also being
popularly used for oil extraction from different spice. Carbon
Dioxide in liquid form is used as a inert and safe liquid solvent
for extracting aromatic molecules. The process is more advantageous,
as there is no residue left at the end of the process. The liquid
carbon dioxide simply reverts back to the gaseous state.