Cannabidiol (CBD), one of the three main chemicals found in the trichomes of the cannabis plant, has gained a lot of attention in recent years as more studies show a variety of potential applications for it. You can find CBD in almost every type of cannabis plant including:
cannabis plants containing THC, the psychoactive chemical that makes you feel ‘high’
industrial hemp plants that contain no THC and have no psychoactive effect
There are a number of ways of extracting CBD from any of these varieties of cannabis. If the plant you start with contains only CBD (like industrial hemp or a high-CBD cannabis strain); there are multiple extraction methods which are very simple and require little equipment.
The most common methods use some type of solvent. This can be a liquid solvent, CO2, or an oil solvent. If the plant material you start with contains THC as well as CBD (such as smokable cannabis), the process to separate CBD from other cannabinoids is more complex and generally requires professional equipment. To avoid getting too technical, let’s look mainly at extraction methods for CBD-only plants.
In this method, plant material like flowers and trim are put into a container. Liquid solvent (usually butane, isopropyl alcohol, hexane, or ethanol) is run through the plant matter to strip it of cannabinoids and flavors and transfer them into the liquid. Then, the liquid is evaporated away from this mixture to leave only concentrated chemicals and flavors in the form of an oil.
Benefits of this method are many— it is the simplest, equipment-free, and inexpensive way to extract CBD, but not without some downsides. One concern is that solvents can leave traces of impurities in the finished CBD oil (meticulous processing methods and the right solvent can minimize this). Also, some liquid solvents remove chlorophyll from the plant along with cannabinoids and flavors, giving the finished oil a greener color and more bitter taste. However, because these negative effects can usually be countered by adjusting specifics in the process, this remains the most common method for CBD extraction.
Carbon Dioxide (C02) is a unique molecule that can function as any state of matter— solid, liquid, or gas— depending on the pressure and temperature it is kept under. Because variables like pressure and temperature have to be kept very specific in a C02 extraction, this extraction method is usually done with a piece of equipment called a ‘closed-loop extractor’.
This machine has three chambers: the first chamber holds solid, pressurized C02 (commonly known as ‘dry ice’), the second chamber contains dry plant material and the third chamber separates the finished product.
When performing the extraction, the solid C02 from the first chamber is pumped into the second with the plant material. This second chamber is kept at a specific pressure and temperature which causes the C02 to behave more like a liquid (although it’s somewhere between a liquid and gas in this state, referred to as supercritical C02) so that it runs through the plant material and extracts chemicals and flavors, much like in the liquid solvent process. Then, the C02-cannabinoid mixture is pumped into a third chamber where it is kept at an even lower pressure and higher temperature so that the C02 gas rises to the top of the chamber while the oils containing chemicals and flavors from the plant material fall to the bottom to be collected for consumption.
There are many benefits of this method. It doesn’t require a long evaporation process like a liquid solvent extraction and there is minimal risk of contaminants in the finished product. Because this method carefully controls temperature and pressure, it can also be used to separate CBD from cannabis also containing THC.
CBD extracts from the plant at a lower temperature and pressure than THC, so careful adjustment of the pressure and temperature in the second chamber can isolate the specific cannabinoid you want to extract. Closed-loop extractor systems are very pricey, however, which is why this type of extraction is generally only used by professional CBD producers.
Many home-producers who make their own CBD products still employ this simple extraction method. First, raw plant material must be decarboxylated, or heated to a specific temperature for a certain length of time to activate the chemicals in the plant. Plant material is then added to olive oil and heated to 100°C for 1-2 hours to extract the cannabinoids. With this method, the olive oil cannot be evaporated away after the process, so users must consume much higher quantities of this type of extracted oil than the highly-concentrated oil produced by other methods. Infused olive oil is also highly perishable, and so must be stored in cold, dark place.
This makes it unviable for commercial CBD producers, but a simple, safe, and inexpensive option for individual enthusiasts.
While these are currently the most common methods in which CBD is extracted from cannabis or hemp; technology in this exciting new field is constantly updating, so new methods will surely be seen in the coming years as the industry expands.
Each extraction method is best suited to specific circumstances: whether you are a company or an individual, for what type of product you are extracting CBD, desired flavor, strength and consistency all play a part in which method should be chosen. Companies producing CBD often put extracted CBD through subsequent processes to make a variety of other products.
This is intended to update the last article on the many methods of extraction for industrial hemp. I spent a lot of time at the last Cannabis trade show, talking to vendors and extraction experts with lots of different types of equipment. I see that one of the biggest problems to progress as an industry as a whole is contingent upon the community having as accurate as information as possible. I do understand that in some people’s minds, this could put me and my efforts at processing at a competitive advantage, because the competition will benefit from this. From my perspective, this is a small price to pay to educate the industry with the best information possible. I would also like to stress that an industry benefit for openly sharing information like this is it allows more farmers and individual businesses to benefit from the Industry. From my perspective, we need lots of innovators making end products to help people, and to create more demand in the market for this great industry. To this end, I feel that if I can empower more small farmers to be able to product higher end raw material, and this means being able to sell individual Cannabinoids or high-quality extracts at a reasonable price. Hopefully this will help create a more equitable profit sharing and cooperation based model in the industry, which I would like most to support smaller, localized, organic farming. So much of this article is, in a way, with those motivations as a backing: transparency, accuracy, and with cooperation and innovation in mind.
At the Cannabis conference in Las Vegas, I spoke to people selling CO2 equipment, but also discussed a high-volume alcohol processing system, and some passive closed loop solvent systems. I didn’t get the kinds of answers that I wanted from the CO2 extraction teams. Regarding the energy usage, the most fuel efficient of the CO2 systems still would pull 5 220V, which is still enormous. The second issue with CO2 has to do with the material forming carbonic acid, and rotting the material, which creates carcinogens and toxins, and can encourage bacterial growth. There weren’t adequate answers to that question, either. Most claimed to ‘recycle’ the solvent, but I saw none that addressed the fact that water and carbonic acid forms within minutes of the CO2 entering the extractor, and this problem gets worse when the solvent is recycled.
So that leaves the producer with two options: first, they can discharge the solvent, which is already extracted from crude oil products. So, CO2 is really not much different than butane from that perspective, they are both products of crude oil. Second, they can recycle the solvent, and if they do that, they have to dry the product to such a degree that there is extensive essential oil loss, which has major medicinal benefits. If they do not dry properly, the product will rot right in the extractor and this causes potentially carcinogenic rancid fats to form in the extract. The last problem is the potential concentrations of carcinogens from pesticide use. There have been extracts that have been coming back hot for pesticides and heavy metals recently, and without knowing that the flower comes certified organic, there is no way to know whether the extracts are coming back toxic or not without testing them. This needs to happen, as there is no regulation right now surrounding processing, which can be a concern for consumers. I am not sure right now who is and who is not testing, but I have for a fact seen some product come back rancid, toxic, and with contaminants. We need to focus our purchases on companies with transparent chain of custody practices with their flower and lots of testing for contaminants both in the initial flower and final product. Take a test for yourself to Centennial Seeds or another testing agency and ask for pesticide and contaminant testing. If it’s CO2 oil, before you buy a quantity, make sure to test for rancidity.
Lastly was the cost vs. throughput. Whereas the alcohol or solvent based system can produce 100+ pounds per hour at about 100K, the CO2 extractors were able to extract 12-20 lbs in a comparable day, with around 300k of investment for the equipment. That leaves the solvent-based systems at 20 times the capacity and volume for the same investment cost. If that was a car, that would make one $30,000.00 car with much better performance, up to twenty times less environmental and energy waste, and a much safer end product, with a price comparison to a $600,000.00 car. I would take the better, more fuel efficient, less dangerous car for $30,000.00.
Moving on from the difficult CO2 topics, to ethanol extraction. With an alcohol system, we are able to produce a very high volume of full spectrum extract, which includes bioflavonoids and other products. The one main problem is the ‘fatty acid methyl ester’ that is created as a byproduct of the alcohol reacting with the fatty acids in the product. According to the MSDS safety data sheet, ‘fatty acid methyl ester’ is not toxic, and the only concern would be excessive buildup in the product, which with good processing equipment would not happen.
The last is the passive or active closed loop solvent system, used with an alcohol ether or propane, sometimes butane. These systems are relatively inexpensive, and if you get medical grade ether, or butane, you can ensure that the solvent is free from toxins and will leave a clean product. Some people have an issue with the idea of a fossil fuel, but CO2 is also extracted as a fossil fuel, and is expelled after extraction after a single time, if they say they recycle it, then it becomes toxic. Butane on the other hand, can pick up moisture, but will not cause the formation of carbonic acid and will not become toxic after a few uses.
From what I have seen, propane is the cleanest and can last a hundred times or more with the right equipment before needing to be burned off. So even though it got a bad wrap it uses much less fossil fuel, is safer, and incredibly cheaper than CO2. I prefer the quality of this product to the ethanol extract, but the ethanol is technically more sustainable and does not touch fossil fuels at all for the purists out there, it can also be certified organic in its processing. The quality of equipment is just not there in comparison to the closed loop solvent systems, though. We don’t have as much technology available for purchase in the industry for ethanol as we do with closed loop solvent systems.
There are a lot of benefits to alcohol extraction. First off, it is not a fossil fuel, and it only uses 110V plugs and is about 1/5 of the energy consumption of CO2. It is also possible to use organic alcohol with the process, which is about as environmentally friendly as you can get. There are a few good alcohol systems out there.
There are two other kinds of solvent-less extraction methods. Heated Press, and Sonication. Heated Press is a great method, and can be used with keif as well for a very nice oil, but since there are no solvents, the oil has much higher levels of fats and waxes, but there is a distinctly fresh taste.
There was one major delight, and that was the success of a THC removal, Cannabinoid separation system that is set up and ready for use. Separating Cannabinoids can be done in different ways, but all involve chromatography, which means splitting up one thing into its different components, much like light being divided into the rainbow through a prism. Hence “chroma” meaning color, in chromatography. There are many ways to do this, but all of them involve teasing the molecules apart using their weights, boiling points, and the strength of the way they ‘stick’ to other molecules. There are some easy and straightforward ways to separate these out that are in the works right now.
At Enlita Farms, we get the best results and highest quality oils on the market from using our own proprietary processes within active closed loop liquid solvent systems using medical grade, very pure solvents free from toxins. Even after using this approach, we test our batches after processing to ensure that no solvents remain in our oils.