CBD oil in its most basic form is made of two components, an extract and a carrier. The extract consists of the chemical compounds withdrawn from the hemp plant, which are typically then concentrated. The chemical compounds can be extracted using carbon dioxide, ethanol, hydrocarbon, or an oil. The other component is a carrier, which is typically an oil. A carrier oil is utilized to make the CBD extract more suitable for consumption.
At room temperature and standard atmospheric pressure, carbon dioxide (CO2) is a gas, but at cooler temperatures and higher pressures, it turns into a liquid. To extract CBD, liquid carbon dioxide saturates the hemp plant material and drips through. As soon as the temperature warms up and the pressure drops, the carbon dioxide reverts back to a gas and evaporates, leaving behind a highly concentrated CBD extract. To make CBD oil, the extract is then mixed with a carrier or base. CO2 extraction is considered relatively non-toxic and is the preferred method of extraction in the hemp industry.
You may not be familiar with the word ethanol, but does the word alcohol ring a bell? Yup, that’s right—alcohol, otherwise known as ethanol, is used to make CBD oil. In this process, ethanol is poured over the hemp plant material. The hemp is allowed to sit in the ethanol for several hours or up to a couple days. Then the mixture is filtered, leaving behind ethanol saturated with CBD. Next, the CBD-saturated ethanol is heated to evaporate the ethanol, leaving behind a highly concentrated CBD extract, which can then be mixed with a carrier or base to create CBD oil.
Ethanol is generally regarded as safe (GRAS) by the US Food and Drug Administration (FDA) and is an active ingredient in some hand sanitizers and medical wipes. That’s because it’s effective in killing most bacteria, fungi, and many viruses—an important factor to consider for those with compromised immune systems. The trade-off is that ethanol also coextracts chlorophyll, which means an ethanol-based CBD oil might taste like fresh grass clippings.
A hydrocarbon is a chemical made of up hydrogen and carbon. The most common hydrocarbons used to extract CBD from hemp are butane, propane, hexane, and naphtha. In this process, the hydrocarbon is passed through the hemp plant material, which draws out the CBD. The residual solvent is then removed using heat and a vacuum. The heat evaporates the hydrocarbon and the vacuum suctions away the hydrocarbon evaporate (a process known as a purge or purging), leaving behind a highly concentrated CBD extract. The remaining extract can then be mixed with a carrier oil or base to create CBD oil.
Not every CBD extract goes through a purge, and improper purging leaves behind traces of the hydrocarbon. Even if the purging is done properly, it can be difficult to completely purge 100 percent of these hydrocarbons from the hemp extracts. The possibility of trace hydrocarbons, which pose health risks, makes this form of extraction less desirable than CO2 or ethanol extraction.
Oil extraction uses an oil to extract the CBD. Olive oil, grapeseed oil, and medium-chain triglyceride (MCT) oil are the most common oils used to make CBD oil. (MCT oil is made by extracting and isolating medium-chain triglycerides from coconut oil. In general, MCT oil has no taste or smell.)
To extract the CBD in an oil itself, a glass container filled with hemp plant material and an oil is placed over a pan of boiling water—a double boiler, essentially—and heated. Once the mixture cools, it’s filtered and the CBD oil is ready for consumption.
The trade-off to oil extraction is that these oils cannot be further concentrated, meaning patients may need to consume more in order to get the same medical benefits as from a CBD oil made using one of the other extraction methods.