Essential Oil Extraction Methods

Essential oils are extracted using various methods, each of which can influence the oil's constituents and chemistry. The majority of essential oils are extracted through steam distillation. This involves passing steam through the plant material which releases the essential oil. Then the steam and oil are carried through a cooling tube and into chamber where they separate and can be gathered. The water that remains is a hydrosol which has therapeutic value as well.

Citrus essential oils are typically cold pressed from the peel, although some are distilled. Lemon (Citrus limon) essential oil is available in both cold pressed and distilled forms. It is important to note that cold pressed lemon essential oil is photosensitive and should be used with caution on skin exposed to sunlight, whereas distilled lemon oil does not carry this precaution.

Certain delicate floral oils can be damaged during steam distillation. Typically, these oils are extracted using a solvent, which is subsequently removed from the resulting substance. This process yields what is known as an absolute. Jasmine (Jasminum grandiflorum and J. sambac) requires this method of extraction to maintain its constituents, health benefits, and fragrance. Although commonly used as an essential oil, it is technically classified as an absolute.

Supercritical carbon dioxide extraction is a particularly intriguing method for obtaining oils. This process involves introducing carbon dioxide (CO2), which in its supercritical state exhibits properties of both a gas and a liquid, into a sealed chamber containing plant material. This action facilitates the release of an extract from the plant. Subsequently, the carbon dioxide naturally dissipates into the atmosphere leaving the extract behind. The resulting extract includes not only the essential oil but also the plants fatty acids and cuticular waxes, thereby more closely resembling the plant's natural scent and chemical profile. Additionally, it contains heavier compounds than those typically produced through steam distillation. Ginger (Zingiber officinale) serves as an effective digestive tonic. The CO2 extract of ginger contains two potent constituents that enhance the stimulation of digestive juices, fortify the digestive tract muscles, promote bile flow, and improve peristalsis, which is the movement within the digestive tract. While CO2 extracts are utilized similarly to essential oils, they are technically classified as extracts.

There are several other extraction methods used to obtain aromatherapy extracts and oils, but I have covered the main ones here.