The use of aromatic plant extracts and essential oils has been embraced by civilizations for thousands of years. Through crude extraction methods, ancient cultures derived aromatic oils from seeds, roots, bark, leaves, wood, flowers and resins and used them in religious ceremony, perfumery, funerary services and many other aspects of life. In the early Orient, Greece and Rome, the oils were obtained by placing plant material into a fatty oil, leaving them to warm in the sun and finally separating the out the aromatic oil. Throughout the early Middle Ages and beyond, a form of distillation was used to prepare floral and aromatic waters.
Today, steam distillation is the most widely used process for extraction on a large scale and is the standard method for producing essential oils. Steam distillations cause sacs in plant material to open up and release their oils, but this process can’t extract heavier compounds, and some constituents can be damaged due to the high heat. Solvent extraction methods produce absolutes, which are different from essential oils because they can contain both aromatic and non-aromatic chemical constituents. The disadvantage is there can be trace amounts of the solvent, typically hexane, heptane or ethanol, in the finished product.
A relatively new and highly efficient process is CO2 extraction. CO2 extracts are oils similar to distilled essential oils and can be tremendously beneficial when used in aromatherapy. The process consists of pumping pressurized carbon dioxide into a chamber filled with plant matter. When carbon dioxide is subjected to pressure, it has liquid properties while remaining in a gaseous state. Because of these liquid properties, the carbon dioxide functions as a solvent, pulling the oils and other substances, such as pigment and resin, from the plant material.
The difference between CO2 extraction and traditional steam distillation is that CO2 is used as a solvent instead of heated water or steam. Let’s compare the differences in the two methods:
Temperatures of about 95 to 100 degrees F.
Superior in many cases due to lower heat exposure of plant matter.
Extracts contain more plant constituents.
More full-bodied aroma, closely resembling the herb it is derived from.
As this newer method of extraction becomes established in aromatherapy, more choices are emerging. Here is a look at several commonly CO2 extracted oils and their uses:
Calendula (Calendula officinalis) – Most recognized for its ability to help wound healing, ulcers and abrasions, a CO2 extract contains, not only all the essential oils of the plant, but also the plant waxes and heavier phytochemicals. This extract can be used in healing salves, lotions, creams for chapped, dry or damaged skin. Recommended use 1-5% in formulations.
Carrot Seed (Daucus carota) – This CO2 is used primarily for its healing properties and its effects on the skin. It helps repair and tone the skin, increase elasticity, and reduces the formation of wrinkles and scars. An excellent addition to face creams, it is useful for balancing oily and dry skin. (Not during pregnancy or nursing.)
Jasmine (Jasminum grandiflorum) – An uplifting aroma which encourages a focused mind. A Jasmine CO2 possesses a very rich, floral aroma that is wonderful in perfumes. The aroma is very concentrated, and a little goes a very long way. Dilute in Jojoba to fragrance your most special formulations. (Not for children under 5 years.)
Ginger (Zingiber officinale) – A Ginger CO2 has a very warm, spicy and more complex aroma that that of the distilled essential oil. This should be used sparingly due to its intensity, diluted and added gradually to blends until the desired effect is achieved. It is especially well suited for natural perfumery to introduce warmth and a spicy sweetness. (Not for use with anti-coagulant medications, not for use in the bath, not for sensitive skin.)
Arnica Flower (Arnica montana) – With amazing anti-inflammatory actions, this extract is an excellent choice for salves and ointments for bruises. Also known to support healthy hair growth, 1-2% can be added to hair care preparations.
Evening Primrose (Oenothera biennis) – This CO2 is naturally rich in the gamma-linolenic essential fatty acid and is exceptionally nourishing to the skin. Since the human body doesn’t produce essential fatty acids, it’s important to obtain through diet and topical application. Essential fatty acids inhibit bacterial growth and defend against infection and inflammation. Evening Primrose is highly beneficial for dry skin problems including eczema and psoriasis.
Vanilla (Vanilla planifolia) – Vanilla CO2 extract is usually added to blends to help sweeten, soften and deepen the fragrance. Suitable for all ages and genders, the rich aroma blends especially well with essential oils and other natural aromatics in the spice, citrus, mint, herbaceous and wood categories.
Coffee Bean (Coffea arabica L) – The uplifting scent of this extract is the rich, warm, smooth aroma of fresh roasted coffee. Known to reduce puffiness, fine lines and wrinkles, it is a suitable choice for cosmetics, skin and body care products. This extract contains Cafestol, a diterpene, which is under study for its diverse pharmacological benefits. It is also used in perfumery and is considered a base note. (Contains 0.5% caffeine: avoid if sensitive.)
A CO2 extraction produces the most therapeutic oil from many plants, but not all. It is highly beneficial for resins such as Frankincense (Boswellia carterii) and Myrrh (Commiphora myrrha) as more of the heavier compounds, and important healing properties, are brought into the finished product. A CO2 extraction can be important when rare or endangered plant species are involved, such as Sandalwood (Santalum album) since less of the plant is needed to produce an equivalent amount of oil.
However, some oils are best steam distilled. German Chamomile (Matricaria recutita) for example, only produces the anti-inflammatory of chamazulene when distilled by steam. Other herbs, extracted with CO2 processing, are more complete, with added properties, or just a little something special in the aroma. Our desired results should be the determining factor in whether we choose an extract or an essential oil as great benefit can be derived from both.
Tisserand, Robert and Young, Rodney, Essential Oil Safety, Second Edition, Churchill Livingstone Elsevier, 2014, p 233, 234, 294, 311, 462, 463
Lawless, Julia, The Encyclopedia of Essential Oils, Conari Press, San Francisco, CA, 1992, 2013, p 39, 63, 101,115, 197
Purchon, Nerys and Cantele, Lora, The Complete Aromatherapy and Essential Oils Handbook for Everyday Wellness, Robert Rose, Inc., Toronto, Ontario, 2014, p 43, 67, 131, 141, 417
Research provided by Natalie Zalenka, Aroma Apothecary Healing Arts Academy, Mastery Level graduate. Thank YOU!