So the number one question we get when talking about our extraction equipment is “can I see it operating?” While we are always inviting (and people o...
CO2 Extraction Demo
November 12, 2017
SuperCritical CO2 Extraction ... The Little Monkey that Could
May 1, 2016
CO2 extraction is now the primary method for extracting cannabis in the United States and around the world. This process is a high-pressure system using carbon dioxide under high-pressure to extract the lipophilic fractions from cannabis. The lipophilic compounds are the oils, fats and resins that are of the greatest value to the cannabis user.
It is a safer method in that it does not use any chemical or harsh solvents such as butane or propane. This means that it is also nonflammable and safer during the production process as well as providing a guarantee there will be no residual solvents will be in the finished product. As a high-pressure system still has safety concerns most of which could be managed successfully using automated software safety shutdowns, physical safety shutdown's, and blowout valves as a final safety measure. For the local extractor it is essential that such measures are in place to protect their staff from injury. CO2 itself is a safe gas that dissipates quickly if a leakage occurs.
CO2 extraction has two basic forms, subcritical and supercritical. Subcritical means that the CO2 under pressure is maintained in a liquid state. Supercritical means that the CO2 gas vacillates between a liquid and a gaseous state. Subcritical CO2 extraction is less desirable because it extends extraction time and reduces efficiency. It requires less technical expertise to achieve in a simple extractor model but the results are less than optimal, so for the purposes of this article we will focus on supercritical as it is most desirable method required for cannabis extraction.
Supercritical extraction uses CO2 gas under high-pressure while keeping it near room temperature. This causes the CO2 to obtain a constant state of flux. Think of it like a little monkey reaching up to a banana tree and grabbing the bananas one at a time. CO2 in it's gaseous form it will penetrate the herbal fibers (monkey reaching into the tree) then when it shifts back to a liquid it brings the lipophilic (fat soluble compounds) out of that fiber (like the monkey's hand grabbing the banana). Just like the little monkey, CO2 keeps reaching in to grab those molecules for the entire cycle until all of the fat molecules are transferred from the extraction chamber to the separator where it is expelled.
The equipment involved in this extraction process basically has an extraction chamber that wholes the ground raw herb, a manifold system that has vales and safety features, a pump that pushes the supercritical CO2 through the equipment and a separation chamber that receives the extracted fats and oils. Of course there is a great deal more to it than that but you get the picture.
Now monkeys don't grab leaves or banana flowers, just the bananas, and in similar fashion the CO2 doesn't pull out the hydrophilic compounds (water and alcohol soluble compounds). In some herbal extractions these hydrophilic compounds are desirable so a post CO2 extract is necessary. That just means that the material will be removed from the extractor after the first extraction and placed into a bath of alcohol or water depending on the exact polarity of the compounds you are trying to pull out. It's kind of like making tea if you are doing a water extract or like a mojito (crushing mint leaves in a glass of rum) if it is an alcohol extract.
So the resulting extracted fats, oils and resins are now ready for post production processing. The raw oil contains trace amounts of entrained water, waxes and heavy fats that need to be separated from the oil so that the oil can be used for vaping. The heavier compounds can easily be used in edibles or topical products but not for vaping or any form of inhalation.
In the cannabis industry it is often the goal of the processor to preserve the flavors and aromas of the original plant. Supercritical extraction is well suited to preserving those tastes and smells as they are mostly lipophilic in nature. In fact in the aromatherapy market CO2 extracts are the norm because the aromas are so close to the raw plant that other more traditional methods are being abandoned. Additionally, new flavor companies have popped up around the world, over the last decade and they use CO2 extracts to allow commercial chefs to increase the flavoring of their products which having to add such a large volume of flavoring material (which would effect the cooking time and other physical aspects of cooking).
Now at the end of the process when the little monkey is done removing all the bananas he his called back to his family to do it again. So to keep with this analogy, well designed machines will recycle their little monkey (the CO2, in case you missed the point in this silly example). This step should recapture 95% of the CO2 used in the process. To remove the CO2 from the extract, the machine will simply release the pressure and just like when you open a can of soda the CO2 is released back to it's natural gaseous state and then recovered back to the supply tank.
Supercritical CO2 extraction is hands down the best way to extract cannabis and a variety of other herbs, primarily because it is a low temperature, gentle process that is safe and uses no chemical solvents. Many producers are switching to this relatively simple and cost effective method to make safer, and better products. So remember the little monkey and all he can do for herbal extraction.
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