In our last blog post, we learned a little about the history of aromatherapy and its modern
expression. We also discussed distillation, the main process of extracting the valuable essential
oils of a therapeutic plant or fruit. Today we’ll talk about other methods of extraction, how
they work, and their roll in aromatherapy.
Cold Pressing (also sometimes called expression) is another important method of extraction
used today, especially for delicate citrus essential oils. Historically, this process was done by
hand. The zest or find of the citrus was first soaked in warm water to make the rind more
receptive to the pressing process. Next, sponges were pressed against the rind to break the oil
cavities and absorb the essential oils. Sponges were pressed over storage containers, and
allowed to rest until oils and juice separated. Today, the majority of modern cold press
techniques use centrifugal force. The spinning in the centrifuge separates much of the essential
oil from the juice.
These cold pressed oils contain a vibrancy sometimes lacking in distilled essential oils. They
have also not been heated (beyond the heat that is generated through friction). In cases where
tangerine, lemon, bergamot, sweet orange, or lime are desired look for cold pressed or
expressed essential oils.
Hydrosols were originally a byproduct of extraction. However, today, they are seen to have
their own therapeutic value and some distilleries focus primarily on these delicate waters.
When plant material is steam distilled the chemical compounds of the plant first accumulate in
the water. Only after they reach maximum solubility in the water do they separate in a layer of
oil on the surface. Many of the water-soluble plant compounds and some of the oil-soluble
compounds wind up in this water. Hydrosols are usually clear and have the viscosity of water.
Their aroma is usually similar to that of the essential oil, but is usually quite subtle. Hydrosols
can used in toners, creams, lotions, body sprays and room sprays. Many people use these
hydrosols because they are generally safer for use with babies and those with immune
disorders. Please consult a medical profession before using any hydrosols with these
Solvent extraction is used in cases where the plant material is too fragile to be distilled.
Petroleum ether, methanol, ethanol, or hexane are used to extract lipophilic material from the
plant. The solvent will also remove the chlorophyll and other plant tissue, resulting in a highly
colored or thick extract. The first product of this process is called a concrete, which is a
concentrated extract containing waxes and fats as well as the valuable aromatic compounds.
This concrete is then mixed with alcohol, which removes the aromatic principle from the
material. This end product is known as the absolute.
Solvent extraction is used for jasmine, tuberose, carnation, gardenia, jonquil, violet leaf,
narcissus, mimosa and other delicate flowers. Neroli and rose can be distilled or solvent
extracted, and this will generally be indicated on the label and in the product catalog.