CBD Extraction: CO2, Steam Distillation, and More

Cannabidiol, or CBD for short, is an organic compound that is found in the cannabis plant, with the flowers of the hemp plant being the richest source. And in order for CBD to be added to a wide array of consumer products—think CBD oil, lotions, topicals, or CBD vape juice—the first step that manufacturers need to take is to extract it from the plant.

This guide will present the various CBD extraction methods, essentially explaining how full-spectrum CBD oil is obtained from the CBD strains of cannabis. Some of these methods have been used in various industries for decades or even centuries, far before CBD oil was even a thing. Examples include essential oil extraction, decaffeination (and caffeine extraction) of coffee beans, and even beer production. In all cases, the idea is the same: how to extract a valuable resource out of plant material.

If you are interested in the ins and outs of CBD extraction from cannabis strains high in CBD, here's a breakdown of the most commonly used CBD methods.

Supercritical CO2 extraction

The word "supercritical" sounds real fancy, but it is actually a term that's very commonly used in chemistry. Simply put, a substance in its supercritical state possesses characteristics of both a gas and a liquid.

When supercritical CO2 is used in CBD extraction, its gas properties allow it to effuse through all plant matter, while its liquid properties allow it to extract compounds efficiently. The exact process varies, and some labs start the extraction with liquid CO2 while others start with CO2 in gas form. In both cases, manufacturers add CO2 in a chamber that includes plant material and use the exact amounts of pressure and temperature needed for CO2 to reach its supercritical state. At this point, and with the help of some additional heat, CO2 acts as a solvent and causes the plant material to separate, carrying with it all the essential compounds. Once done, CO2 is separated from the organic compounds, and manufacturers are left with full-spectrum CBD oil.

While it requires qualified personnel and there are higher costs associated with the equipment needed for supercritical CO2 extraction, it is by far the most efficient and quickest method to extract CBD. It is also environmentally friendly due to the limited amount of emissions, and safer than extractions that use certain solvents as CO2 is "generally regarded as safe" by the FDA.

Steam distillation

Steam distillation is a centuries-old process that’s commonly used to distill alcohol as well as extract essential oils from organics. The process is much less complicated than CO2 CBD extraction. First, plant matter is introduced in a distillation tank. With the use of water and heat, the produced steam carries oils to the top of the tank, and it is then passed through a condenser, resulting in a mix of water and oil. The mix then goes through further distillation to separate water and oil, and the result is full-spectrum CBD oil.

While this CBD extraction process is much simpler, there are some downfalls. It is more prone to error, much less efficient, and may potentially damage part of the essential oil profile of the plant. Due to these reasons, steam distillation is very rarely used to extract CBD nowadays, but many labs still use some type of distillation in the process of isolating CBD from full-spectrum oil.

Solvent extraction

This method is also centuries old and is somewhat of a middle point between CO2 extraction and steam distillation when it comes to complexity and efficiency. It bears many similarities to CO2 extraction, albeit without the advanced methodology that’s behind the "supercritical" part.

In layman's terms, this type of extraction involves mixing plant material with some type of solvent that will carry the essential oils given the right conditions and enough time. Some of the most popular natural solvents are alcohol (ethanol) and natural plant oils (including olive oil), with alcohol being much more efficient in dissolving the plant’s compounds. But due to the higher cost associated with ethanol, many manufacturers choose to go with synthetic solvents (hydrocarbons like butane or hexane), which may end up in lower quality, or even CBD oil that's unfit for consumption if they're not removed properly from the final product.

Solvent extraction is a delicate CBD extraction process and its pros and cons, as well as the consistency of the resulting oil, varies greatly depending on the solvent used. It can be more efficient than steam distillation if performed properly, but it carries a lot of risk and most labs choose CO2 extraction if they can afford it.

How to extract CBD at home

Olive oil extraction

Possibly the simplest way to extract CBD oil, as it only requires some CBD-rich bud, olive oil, and some basic kitchen equipment to ensure a steady supply of heat. If you’ve ever made cannabutter, then technically you have already utilized this method before. The only difference in this case, is that you are using hemp and olive oil—but olive oil can easily be swapped out for the oil or butter of your choice. This includes regular butter, coconut oil, hempseed oil, etc.

The first step for olive oil extraction is decarboxylation, i.e. activation of the compounds of plant material with the use of heat (there’s more info in the following section). Trimmed hemp flower in an oven tray heated between 240 and 280°F (115-135°C) for up to an hour should do the trick. Once this step is taken care of, the resulting activated cannabis is mixed with olive oil and heated at low temperature (ideally in a double boiler) for around two hours. The only thing left to do at this point is to use a filter to strain the mixture and separate the oil from the plant material. The result: CBD-infused olive oil.

While this is the easiest and least risky way to extract CBD oil, it is certainly not the most efficient. As with most DIY projects, there's always room for user error. But even if you do everything right, you are going to sacrifice a large part of the organic compounds of the plant and you will produce less potent oil than a lab would. For these reasons, extracting CBD at home is an interesting experiment, but if you want to reap all the benefits of CBD it is advisable to get it from a reputable source instead.

Activation and purification

Decarboxylation

The active organic compounds of the cannabis plant come in their acidic forms. In order to go from THCA and CBDA to THC and CBD, manufacturers need to apply heat and decarboxylate the compounds—that's the lab equivalent to lighting up a joint. Heat removes a carbon molecule from the organic compounds and turns them into their active counterparts.

Decarboxylation may take place before or after the extraction, and the exact methodology followed is highly dependent on this choice. But it is an essential part of the CBD oil production process, as non-activated compounds have little to no effect on the user.

Winterization

While not as essential as carboxylation, winterization is a very common process that ensures that the final product of the extraction is as pure as possible. Simply put, the process of winterization employs solvents (usually ethanol) and low temperatures to ensure that lipids and other impurities are removed from an oil extract. This takes place as one of the final steps before full spectrum oil is obtained.

Winterization is not always performed, but it is a very important process when the final product is intended to be vaped. Some terpenes and other compounds are also filtered out during this process, but many manufacturers choose to add terpenes to their CBD oil after winterization.

CBD extraction: the takeaway