It is possible to use different extraction methods and this depends on the kind of plants ,on the tissue cointaining the essential oils and on its physical properties.

Mechanical procedure : pressing and squeezing
This method is suitable for the extraction of essential oils present in the epicarp, the most external part of the fruit ( skin), such as orange, lemon, bergamot,mandarin and cedar.
Generally the extraction follows a cold procedure as it is typical for precious oils.
From the pressing process you obtain a mixture of oil, water and juice which will be filtered and centrifuged to separate the different substances.

Cold absorption
This method is used for very delicate parts such as internal flowers and petals that can not tolerate too many manipulations. It is also used when the quantity of essential oils is so small that it is not possible to separate them through distillation as they would disperse into water.

Procedure with volatile organic solvents
his method is used for plants with a delicate perfume and with a small quantity of essential oils which can be easily altered by the temperature increase during the distillation. For this procedure we use a machine where we put a particular drug that then is treated by a proper solvent.
This solvent must not react with the essential oil, have to be soluble in water, have a low level of toxicity and faint or at least not bad smell.

Distillation
This method is used to extract essential oil from most plants. In this kind of extraction we take the most of some physical properties of the essential oils . In fact the distillation is a process through which the essential oils are separated from the tissue of the plant containing them through steam. This process is complicated and there are different distillation methods according to different conditions: direct distillation or distillation with direct fire, distillation with steam current and distillation with reduced pressure.