What’s the difference between an Essential Oil, a CO2 Extract and an Absolute?

by Jade Shutes

While essential oils, CO2 Extracts and absolutes are all considered aromatic extracts, what makes them unique is their method of extraction and the resulting chemical composition of each type of extraction. This article has been created to help you decipher how these aromatic extracts are unique & different and yet also similar.

First, let’s walk through each of these different methods of extraction so as to better understand how these aromatic extracts come into being.

What is an Essential Oil?

An essential oil is the aromatic extract that is steam distilled utilizing different parts of aromatic plants.

ESSENTIAL OILS are highly concentrated aromatic extracts that are distilled or expressed from a variety of plant material, including flowers, flowering tops, fruits/zests, grasses, leaves, needles and twigs, resins, roots, seeds, and woods.

Aromatic plants contain a complex array of molecules that support the plant in responding to the environment as well as to ensure its survival (think pollinators!). To capture the essential oil, aromatic plant material, be it from seeds, roots, flowers, leaves, needles, cones, resins, or wood, is placed in a distillation unit, whereby steam is introduced to draw out the volatile (aromatic) molecules transforming them into a physical liquid extract we call: an essential oil.

Watch a Rosemary distillation with Jade to see distillation in action!

Essential oils may also be produced via a process known as expression. This extraction method is specific only to citrus fruits, and literally squeezes out the essential oil compounds from the peel of fruits like lemons, limes, grapefruits, tangerines and oranges.

Both of these extraction processes yield what is commonly called: essential oils.

What is an Absolute?

An absolute is an aromatic extract obtained via the process of solvent extraction. Solvent extraction has traditionally been used to extract the aromatics from plant materials that are unable to be distilled due to their delicate flowers. Flowers such as: jasmine, gardenia, violet leaf, tuberose, and lotus, and a few other kinds of plant materials. Solvent extraction uses solvents, specifically petrochemicals like hexane, to pull out the fat soluble aromatic compounds of the plant.

Unlike the steam distillation process that only pulls out the volatile aromatic molecules, solvent extraction also pulls out other types of compounds from the plant like pigments and waxes – making the resulting extract thicker and more viscous and deeper in color.

Additional processing creates the finished extract called an absolute.

Absolutes are widely used within the botanical perfume and cosmetic fields. Absolutes are also finding their way in the repertoire of aromatherapists due to their beautiful aromas and benefits to the skin and psyche!

Concerned about the use of petrochemicals to obtain absolutes? For sure, it is a concern particularly due to the environmental impact of these petrochemicals and their potential impact on our health. So even thought the final absolute contains only a few parts per million, we leave it up to you and your own philosophy to decide if you would like to use or not.

What is a CO2 Extract?

With CO2 extracts becoming more and more available and popular, we find we’re being asked a lot more often: What are CO2 extracts?

In this process, a plants aromatics and/or fatty oil content may be extracted by carbon dioxide gas pressurized at ambient temperatures. At high enough pressures, the CO2 becomes “supercritical,” which means that it exists in a physical state that is neither gas nor liquid, but displays properties of both.

Supercritical CO2 functions as a solvent that extracts aromatic oils from plants. These extracts can manifest properties of both essential oils and whole plant oils (lipid components. By varying the pressure of the system, it is possible to customize which constituents are pulled from the plant, and what kind of oil is produced. Lower pressure extracts are more akin to essential oils, while higher pressure extracts display properties of the whole plant, containing more of the higher molecular weight, thicker and waxier lipophilic constituents.

Once the extraction is complete and the pressure released, the supercritical CO2 becomes a gas and rapidly dissipates. This leaves the oil unadulterated with chemicals, in contrast to petrochemical solvents like hexane, which retain contaminants in the final product.

Supercritical CO2 methods have several advantages over other extraction processes. They occur at lower temperatures than steam distillation, thereby preserving delicate volatile constituents, the solvent is nontoxic, odorless, and readily removed from the final product, the oils are more stable and have a longer shelf life, and the extraction process is environmental friendly!

You may find CO2 extracts listed as Total Extracts or Select Extracts. What’s the difference?

Total extracts contain all the possible CO2-extracted components from the plant material, which can make them quite thick and a bit challenging to work with. The essential oil content can vary between 3 and 50% of the total extract, with the remaining extract being composed of waxes, lipids, and the like, depending on the plant material.

Because total extracts contain the lipid components, there are some incredible CO2 extracts that act more like carriers or herbal oils. CO2 extracts in the herbal oil palette include Arnica CO2 total extract and Calendula CO2 total extract.CO2 extracts in the carrier oil palette include Sea Buckthorn CO2 total extract, Rosehip CO2 total extract and even Raspberry!

To work with thicker CO2 extracts, simply warm them in water and allow to gently heat. Warming thick CO2 extracts helps make them easier to use.

Select extracts contain mostly the essential oil components, which can make up 35% to 95% of the extract. Select extracts are not viscous like total extracts and hence are easier to use.

Select CO2 extracts contain many of the same constituents as their essential oil counterparts, although they may also contain some components not found in essential oils. For instance, the essential oil of ginger (Zingiber officinale) does not contain the bitter principles (shogaol, gingerols), but the CO2 extract does. Select CO2 extracts are known for their strong similarity in aroma to the actual plant aroma, versus the essential oil, which can smell slightly different from the actual plant.

NOTE: Due to the potential of pesticide residue in CO2 extracts, we recommend organic CO2 extracts only.

Whether one uses essential oils, absolutes, or CO2 extracts, one will truly be inspired by the rich aromatics each of these types of extracts offers.