A Definitive Guide to Cannabis Extraction Technology
Supercritical/Subcritical Fluid Extraction 「CO2 Extraction」
High Quality Close-Loop Supercritical Extraction System
What is Supercritical Fluid Extraction?
Supercritical Fluid Extraction utilize supercritical fluid as solvent to extract plant materials from desired plants. Common fluid used for supercritical fluid extraction is Carbon Dioxide, which is known as CO2. Therefore, supercritical fluid extraction is also widely known as CO2 Extraction. By bringing carbon dioxide over the its physical critical points on both pressure and temperature, carbon dioxide will enter a special phase called “supercritical phase”. In such phase, carbon dioxide will have the physical properties of both “Liquid” and “Gas”. As gas, supercritical CO2 can move easily through solids. While as liquid, supercritical CO2 can efficiently dissolve compounds into the solution. These supercritical properties make supercritical fluid extraction very efficient and optimal for botanical extraction.
Subcritical is very similar in terms of extraction principle but utilize fluid right under its critical temperature which gives fluid a more gaseous properties so that it can get into more space between plant particles. Subcritical extraction is very ideal in extracting high quality terpenes from the cannabis plant.
How does Supercritical Fluid Extraction/CO2 Extraction work for cannabis?
During cannabis extraction, CO2 will first be liquified by running through a heat exchanger. Then the fluid will pass through a sequence of mechanical apparatus to bring it into a supercritical phase. Then, the supercritical fluid will flow into the extraction vessel where plant materials are stored at. In the extraction vessel, supercritical CO2 is going to enter the trichomes, dissolving the cannabinoids, terpenoids, flavonoids and many other more organic compounds and move them into the solution.
Next, the solution will flow into a set of cyclonic separation vessels set at different pressure and temperature. Within the cyclonic separation vessels, pressure and temperature will drop significantly comparing those of extraction vessels. Carbon dioxide will change back into gaseous state in the cyclonic separation vessels, dropping off the organic compounds dissolve from extraction vessels. Then it will pass through the separation vessels, gravity is there to ensure the fluid is free of residues before carbon dioxide move to condenser and ready for the next extraction cycle.
Crude extract can then be collected at the outlet of separation vessels. The crude, when the machine is tuned properly, should be shown as a rich and concentrated resin. Wax and chlorophyll still present in the crude and need to run through further purification process such as winterizaiton, distillation and remediation to get desired final compounds.
Advantages and Challenges of using Supercritical Fluid Extraction/CO2 Extraction for cannabis?
The supercritical Fluid Extraction process is known for its safety, efficiency, and tunability. With wide range of temperature and pressure control capability, different compound solubility can be monitored and obtained. Even though it is expensive and technical to operate a supercritical fluid extraction at low volume, it obviously flipped the coin when operating at larger scale. With high quality and consistent output close-loop CO2 Extraction machines(HumBay Technology TruXtrac Series), CO2 can be recycled between extractions, making the operation highly cost-efficient and safe.
Supercritical Fluid Extraction/CO2 Extraction is Best to Produce Following Cannabis End Products:
Ethanol Extraction 「alcohol extraction」
What is Ethanol Extraction?
Ethanol Extraction is a 「solvent extraction method」 that utilizes ethanol as a medium/solvent to extract organic compounds from the plant. Ethanol Extraction is widely used in the botanical extraction industry because of its scalability, cost-efficiency and general safety. Furthermore, ethanol is also known as the 「Universal Solvent」.
How does Ethanol Extraction work?
Ethanol extraction can be operated at different temperature level to achieve different solubility. Generally Ethanol extraction for cannabis plants starts from chilling process where ethanol is cooled down to -20 degree Celsius (-4 degree Fahrenheit). Then ethanol will be pumped into a container that has prefilled with cannabis plants. Plant needs to be fully soaked in the ethanol solution for organic compounds to fully dissolved into the solution. Then the plants will be removed in a “tea bag” fashion. Solution will then flow into an evaporator to evaporate and recycle ethanol used in the previous process. Next, the solution will need to run through further distillation apparatus for finer residue removal process.
Advantages and Challenge of using Ethanol Extraction?
Ethanol Extraction is very ideal to process large volume extraction with acceptable set-up cost. When a high quality close-loop ethanol extraction system is purchased, However, a couple of challenges also presents to ethanol extraction system. Major obstacles are refinement process and lack of selectivity. As a universal solvent, ethanol can also dissolve lots of unwanted components from the plant which will later require more refinement and remediation. One of them is chlorophyll, which is not harmful if left in the extract, but it will impact the flavour by giving a grassy taste and also introduce the green-brownish hue to the extract. Another challenge is ethanol extraction system does not have the component selectivity as CO2 extraction systems. which mean you have to extract everything from the plant and later remove the unwanted part instead of targeting to specific components at the beginning.
Ethanol Extraction is Best to Produce Following Cannabis End Products:
Hydrocarbon Extraction 「Butane Extraction」
What is Hydrocarbon Extraction?
Hydrocarbon Extraction is very similar to ethanol extraction in the workflow process. However, it utilizes hydrocarbon as the solvent instead of ethanol. The most common hydrocarbon used is 「Butane」.Unlike ethanol, hydrocarbon like butane contains only hydrocarbon chain in its chemical structure, and it will only dissolve cannabinoids and terpenoids.
How does Hydrocarbon Extraction work?
Hydrocarbon extraction process normally starts with a washing operation where cold butane will run through plant materials in a container. Since hydrocarbon extraction dissolve majority of cannabinoids and terpenoids and little unwanted components, little post-processing is required for this extraction method.
Advantages and Challenges of using Hydrocarbon Extraction?
As there is little to no heat is required to hydrocarbon extraction process, volatile components such as terpenoids can be preserved at its maximum availability. This property is also key and most important features to the cannabis community consumers as the flavour is very comprehensive and rich. Also, Hydrocarbon extraction is so far the best extraction method to preserving cannabinoids acids such as THC-a, CBD-a and CBG-a…etc. Cannabinoids acids are the precursor to neutral cannabinoids like THC, CBD and CBG…etc and acids are also key requirement to produce end products “Shatter“.
Challenges to use hydrocarbon extraction includes safety issues and compliance requirements. Even though Hydrocarbon has all the amazing benefits as a solvent, it is highly flammable and volatile. In fact, butane is one of the few hydrocarbon that is generally regarded as safe by the FDA for safe ingestion, but lots of other hydrocarbon solvents are banned by the FDA and can be toxic even with small concentration. Due to this limitation, safety precautions and strict regulation have to be impounded when operating such system.
Hydrocarbon Extraction is Best to Produce Following Cannabis End Products:
What is Solventless Extraction?
As states by its name, Solventless Extraction method does not require any solvents. Solventless Extraction relies on only heat and pressure to squeeze out the oils from cannabis plant. This method is easy to operate but can be labor intensive and requires top quality materials.
How Does Solventless Extraction Work?
Solventless extraction is the easiest and requires lowest technical training in order to operate correctly. It could be as simple as preparing the plant material in a filter bag and hit the touch screen or pull down the manual switch to have the machine start pressurize. Wait for a few minutes and you will see the cannabis oil being squeezed out.
Advantages and Challenges of Using Solventless Extraction?
Set-up cost is the lowest when comparing to other solvent-based extraction systems. Easy to operate and do not need much preparation and post-processing work to be done.
However, the entire operation have to ensure sterilized in order to avoid any possible contamination. Furthermore, it is not very ideal to run Solventless Extraction in large volume extraction. Problems like flower preparation, storage, labor cost and production rate are key scalability factor.