Cannabis Extraction Methods

There are various methods used to extract phytocompounds from the cannabis plant. Extraction is valuable when specific substances contained within the cannabis plant are required. Among different extraction methods, there will be distinct advantages and disadvantages. The most commonly used methods are butane extraction, supercritical CO2 extraction, ethanol extraction, water extraction and isopropyl extraction.

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What is cannabis extraction?

Cannabis extraction is the process of separating and isolating cannabinoids from the cannabis plant. A range of different methods are used for this depending on the priorities of the ones doing the extraction. Extraction can be done on a range of compounds within the plant including terpenes and cannabinoids like CBD and THC.

Why is cannabis extraction necessary?

Cannabis extraction is necessary to isolate specific compounds within the cannabis plant, purify them and get them to the ideal concentration. Often, the whole plant is not the ideal format for administering cannabis. In certain situations, a specific cannabinoid may be preferable to the range of them contained within a plant. Certain extraction methods are more suited to extracting specific compounds as well as producing extracts at different purity levels.

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Butane extraction

Butane extraction is a solvent extraction method used for medicinal cannabis extraction. It is also frequently used in other areas such as the food and perfume industries. For cannabis extraction, the process begins by washing high-purity liquid butane over the raw cannabis plant. This dissolves many of the phytocompounds, such as cannabinoids and terpenes, making the liquid into a solution. Sometimes propane is used afterwards to strip additional compounds, such as certain terpenes, from the cannabis plant. After this, the butane solvent must be removed from the solution by using either evaporation or vacuum-drying. Butane extraction is often used to make concentrated cannabis products, some as high as 90%. The extract can be utilised in a range of products such as vape liquid, edibles and topical treatments.

Equipment

Butane extraction typically utilises a closed-loop system of extraction equipment. This includes a butane solvent tank, a material tank, a collection tank, a gas compressor and a condenser tank. The solvent tank is used to store the butane before it’s pumped into the material tank that contains the cannabis plant. After this, the collection tank is used to hold the solution. The condenser changes the solution into a format that makes it easy to collect the extracted compounds.

Pros and cons

This method is useful for its high output, ease of automation and low amount of post-extraction processing. However, it does have a lower output than ethanol when producing low-purity products.

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Supercritical CO2 extraction

Supercritical CO2 extraction is a non-toxic cannabis extraction method, which can be made environmentally friendly depending on how it’s being powered. Supercritical CO2 is carbon dioxide gas which has been heated to a point where it behaves like a fluid. In this method, the heated supercritical CO2 is passed through the ground-up cannabis buds. This breaks up the trichomes and allows part of the plant material to dissolve. These materials flow into a separate vessel where the heat and pressure levels are adjusted. This allows certain molecules to bond with CO2 molecules and separate from the plant matter.

Equipment

Supercritical CO2 extraction involves the use of an extraction vessel, a pump, a release valve, a separate vessel and an internal compressor and heater and a collection vessel.

Pros and cons

The primary benefit of using supercritical CO2 extraction is that the equipment in the process can be automated and that the solvent is highly tunable. Once the process is set up, it can operate in a way that is less hands-on than other methods. It’s also easy to adjust the solvent to the exact level you prefer, giving you more control. Where this method might not be ideal is the high cost, the longer time required and the greater level of post-extraction processing required compared to other methods. Another big benefit of CO2 extraction is that it isn’t flammable like other solvents, making it a safer option.

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Ethanol extraction

Ethanol extraction refers to a group of methods used to extract phytocompounds from the cannabis plant. Typically, ethanol extraction will involve soaking the cannabis plant in grain ethanol. Most modern methods utilise cold ethanol for this purpose. Next, depending on the method, the solution is pumped into an extraction chamber or a centrifuge. At this stage, the extracted compounds are separate from the solvent and collected for use. This method is frequently used in the production of full spectrum CBD oil.

Equipment

While the exact equipment used in ethanol extraction varies, it typically contains a tank to chill the ethanol, an extractor, a filter and a storage tank. 

Pros and cons

Ethanol extraction’s primary advantages are considered to be its cost effectiveness and its ability to create a very pure product at the end of the process. Given its availability, it’s quite economically viable to use ethanol in big batch extraction. It is fairly safe and easy to work with. The downsides to ethanol extraction are the potentially high equipment cost, the high electricity usage and the longer extraction time.

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Water extraction

This solventless method of cannabis extraction works by submerging the cannabis plant in freezing water. When the plant is agitated within the water, the trichomes separate from the plant. The trichomes then pass through a series of screens and result in an oil product.

Equipment

The primary pieces of equipment for water extraction are a container, ice cold water, frozen cannabis flowers and mesh filtration bags or screens. The entire process is conducted in the container. The mesh filtration bags are used to catch the trichomes that have separated from the rest of the cannabis plant.

Pros and cons

While this method is very cost-effective and easy, it does have some drawbacks. Typically, the extract produced has a low level of purity compared to other methods.

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Isopropyl extraction

Similar to ethanol extraction, this method utilises isopropyl alcohol. Dried cannabis flowers are first soaked in this alcohol and gently shaken. This results in the trichomes being stripped from the plant. The mixture is then strained before the solvent is removed using a vacuum. Once the solvent has evaporated, we are left with a THC-rich oil.

Equipment

The main pieces of equipment used for isopropyl extraction are a container, a dish and a vacuum oven. Once the cannabis is soaked in alcohol and agitated, it is strained into the dish. Then, the vacuum oven removes any of the solvent that is still remaining.

Pros and cons

Generally, this method is known to be quite fast and cost-effective, making it good for small-scale production. However, it is not as good at creating a pure product. It often fails to filter out unwanted materials in its final extract. This may mean that more post-extraction processing will be required.

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Kind Medical’s educational resources

Kind medical has a range of educational articles related to medicinal cannabis on our website. Health professionals can also stay informed by accessing our healthcare professionals portal. If you would like some more information, feel free to contact us.