Cannabis extraction is a fine balance between art and science. The art form can only be executed when the science is well understood. For beginners, this can be a steep learning curve. However, once the basics are mastered, the rest comes by quite easily.
And that’s why we have prepared this guide for you.
In this guide, we explore the principles that underpin the art and science of cannabis extraction. It is a detailed guide that touches on the different factors that affect cannabis extraction. It serves as a preamble to a series that we will soon be exploring on the different methods of cannabis extraction.
This guide takes the beginner from the basic science of cannabis extraction to the technicalities that only pros understand. If you are an intermediate or pro you can feel free to jump to the sections that best suit your curiosity. But if you have the time, why not spare half an hour to go through the whole guide? You might just learn something new or if you feel like we left out some crucial information you can leave a comment in the section below.
Table of Contents
- The history of cannabis extraction
- The science behind extraction
- The basic process of extraction
- Solvent-based extraction methods
- Solventless extraction methods
- Chromatography and remediation
- Other extraction methods
- Is it legal to extract cannabinoids?
- The future of extraction
- The history of cannabis extraction
Cannabis extraction dates back to thousands of years ago when hashish was extracted for medicinal use in parts of Europe and the US. Cannabis-based tinctures were in use until the 1940s.
Hashish is made by extracting and compressing trichomes that contain cannabinoids, terpenes, and flavonoids.
In China, India, and Persia, hashish was used for therapeutic and religious reasons.
Initially, open-loop extraction was used. But later, this proved unsafe due to explosions from the use of butane in an open-loop system. Consequently, the closed-loop system was adopted where solvents were enclosed and could be recycled.
It is clear that ancient cultures knew the value of cannabis and how to harness it appropriately.
- The science behind extraction
Extraction involves the removal of different bioactive compounds such as cannabinoids, terpenes, and flavonoids from cannabis trichomes. During the process, the desirable compounds are collected while the undesirable compounds are left behind.
The undesirable compounds may include chlorophyll and lipids.
Most times, a solvent is pushed through the biomass to extract the cannabinoids. However, mechanical force without solvent can also be used to separate the trichomes. This is called solventless extraction.
We will explore these methods later in this guide. For now, let us look at what makes up cannabis extracts.
What are cannabis cannabinoids?
Cannabis sativa is made up of over 500 bioactive compounds, this includes about 120 cannabinoids.
Cannabinoids are behind the rising popularity of cannabis; tetrahydrocannabinol (THC) and cannabidiol (CBD) are the two most popular cannabinoids.
Cannabinoids are bioactive compounds that interact with the body’s endocannabinoid system (ECS) to support health and wellbeing. The ECS, which was discovered in 1992, is a body system that plays a big role in maintaining a state of physiological balance (homeostasis). Cannabinoids influence the ECS through endocannabinoid receptors. Consequently, cannabinoid-based therapy has become a subject of interest to clinicians and researchers.
Apart from THC and CBD, other significant cannabinoids include cannabigerol (CBG), cannabinol (CBN), THCV, and THCA.
Cannabis sativa also contains aromatic compounds known as terpenes which boost the therapeutic effects of cannabinoids.
- The Basic process of extraction
Cannabis extraction is the process of transforming cannabis from a raw biomass to a highly purified extract that is ready for consumption. It starts with processing the raw cannabis in the form of trichome laden female buds or trim and is completed when the final derivative is ready for use.
Below we have outlined some of the crucial steps which include selecting the biomass, pre-processing it, the real extraction, and processing of the derivatives after extraction. However, we will leave out the extraction phase for the next subheading.
Identifying good biomass for cannabis extraction
You should first identify good biomass that will yield the highest amount of cannabinoids. Hemp or cannabis biomass may mean anything from the leaves, stalks, seeds, or trim.
The female cannabis flower produces the most cannabinoids. However, you can still get considerable amounts of cannabinoids from small leaves that are often cut out (trim).
Most processors find it more cost-effective to use trim since buds are usually highly-priced. At the end of the day, you want to get the most value at the best price.
To that end, here are a few things to have in mind when sourcing hemp or cannabis biomass for extraction:
What is the biomass made up of?
The biomass can be made up of sugar leaves (trichomes), fan leaves, or stalks and stems. On some occasions, it may also contain the smaller buds.
The larger buds are usually removed and sold separately. All these parts have value. But for the purposes of extraction, you should be looking for the highest concentration of cannabinoids that you can get at what you consider to be a fair price.
The quality of trichomes
Apart from locating the highest concentration of trichomes, you should be looking for capitate-stalked trichomes which look like little mushrooms. These trichomes fall off easily if they are roughly handled. Since the resin glands are found on the head, make sure that the heads are intact.
You are allowed to use your nose.
Smell the biomass and look for the unique scents of different terpenes. The value of any cannabis product is greatly influenced by its terpene profile. Apart from providing cannabis with its unique aroma, science is now revealing that terpenes contribute significantly to the therapeutic value of cannabis. Cannabis that has not been well cured or stored may have lost most of its terpenes. Biomass ideally should have a fresh earthy smell with floral, piney, sweet, citrusy, or fuel hints.
What are the three different types of trichomes
Not many people know that there are different types of trichomes on cannabis. What most people are familiar with are the iconic silvery trichomes that are visible to the naked eye. These are the capitate-stalked trichomes that measure (50-500 micrometers) and are very prominent during the flowering phase. Most extractors go in search of these trichomes in biomass. At this time, they may have taken a less attractive brownish appearance.
The capitate-sessile and bulbous trichomes are not visible to the naked eye. They may be found on the leaves and stalks of the plant. However, they should not be ignored since they do carry a considerable amount of cannabinoids and terpenes.
Molds and pests
Check the biomass for signs of mold or pest infestation.
Test in a lab
If you are relatively convinced about the quality of the biomass, you should take a representative sample to a third-party lab for testing. At the lab, check for cannabinoid and terpene content. Also check for the presence of pesticides, microbial, and heavy metals.
Pre-processing biomass or “raw” cannabis
Mature female cannabis buds are the raw material for extracting cannabinoids. The milky white or shiny trichomes (resin glands) that coat the surface of the buds are the factories where cannabinoids and terpenes are made. Extraction, regardless of the method, entails separating the trichomes from the plant material and concentrating the bioactive compounds.
This starts with harvesting the mature flowers and taking them through a process of drying and curing the buds to release any excess moisture. The buds or trim may need to be shredded into small pieces to be able to fit into the extraction machine.
Milling the biomass will increase the surface area and provide a larger base for the solvent to act on. This will increase the speed of extraction as the ethanol or CO2 will come into contact with the trichomes sooner.
However, the biomass should only be milled to an ideal size which is about 1/4” particle. This is because there are compounds that should not be extracted from the plant material.
Primary derivatives are obtained through the extraction process.
Processing of derivatives
These are a series of processes that help to get rid of unwanted compounds from the primary derivatives. The aim is to boost the potency and the value of the extract. This may include processes such as winterization, particulate filtration (polishing), solvent evaporation, vacuum oven treatment, or crystallization.
- Winterization: This involves removing lipids, waxes, and fats from the extract. The winterized product is full-spectrum and potent.
- Polishing: This process removes suspended particles from the extract to leave behind a cannabinoid-packed amber liquid that is ready for dabbing.
- Solvent evaporation– This process removes the residual solvent from the derivative through evaporation.
- Vacuum oven treatment– This process uses heat or a vacuum pump to remove residual hydrocarbon from the derivate.
- Crystallization: This involves crystallizing the derivative to achieve almost pure concentrates such as THCA crystals.
- Organic Solvent Nanofiltration (OSN): Multiple filtration steps are used to purify extracted cannabinoids. The steps that may include winterization, decolorization, purification, and evaporation are combined to simplify the process. The derivatives have high potency of up to 90%. Nano-sized filtration membranes are used to filter crude ethanol extract to produce a decolorized, and concentrated extract with high purity levels.
Now we can proceed to the real thing; extraction methods.
- Different methods of extraction; solvent-based
There is no gold standard when it comes to cannabis extraction. This all depends on a number of factors such as your desired end product, budget, and technical expertise. However, the extraction method that you choose should meet industry standards for the potency and purity of the end product.
When choosing the best extraction here are a few considerations to have in mind:
- Extraction efficiency
- Quality of the extract
- Eco friendliness
Generally, extraction methods can be divided into two categories: solvent –based and solventless extraction. As the name suggests, solvent-based extraction involves the use of a solvent while solventless extraction is conducted without the use of a solvent.
Solvent-based methods are more popular than solventless methods for a number of reasons. They are efficient and easy to scale. They are also safe if carried out in compliance with the set guidelines. However, there is a risk of contamination with solvent residue if guidelines are not followed. This makes solventless methods a preferred choice in this regard.
This extraction method has been used for many years, especially by home extractors. Ethanol is easily available, dissolves most non-polar compounds, is easy to use, and eliminates waxes and lipids if performed under optimal conditions. On the flip side, ethanol has relatively low efficiency on a commercial scale.
CO2 (Carbon Dioxide) extraction
CO2 is a common extraction solvent on a commercial scale. This requires sophisticated equipment as the CO2 has to be subjected to precise temperatures and pressures. This method can either be performed at supercritical or subcritical temperatures. Supercritical carbon dioxide extraction is a popular choice for commercial use. It involves subjecting carbon dioxide to supercritical conditions where it has both liquid and gaseous properties. At this point, it can easily dissolve the cannabinoids and extract them, and later evaporated out of the derivative.
Subcritical CO2 extraction uses carbon dioxide at lower temperatures and pressures. The yield is significantly lower but most of the terpenes are preserved.
This involves the use of hydrocarbons such as butane or hexane to extract cannabinoids. The equipment is relatively affordable to purchase and the technique is fairly simple. However, these gases are highly flammable and can easily cause explosions.
- Different methods of extraction; solventless
Solventless extraction is also known as mechanical extraction since mechanical force is used to extract the cannabinoids from the plant material. Since there are no solvents introduced, the risk of contamination with solvent residues is minimal.
Popular methods of mechanical extraction include cold-pressed, rosin press, ice water, and dry sifting.
Below are some of the extracts that are created using mechanical extraction:
This is a form of mechanical extraction where the cannabis biomass is placed under intense pressure at low temperatures to squeeze out the cannabis oil. The biomass is first precooled before it is cold pressed. This is similar to how other cold pressed oils are made.
In this method, the yield is low but most of the cannabinoids, terpenes, and flavonoids are preserved.
Dry sift or kief
Kief is a simple extract that is made by sieving dried trim through a mesh screen to separate the dry sift (trichomes) from the plant material.
The kief can be added to edibles or it can be made into a hash for dabbing.
You can also create a potent multi-strain kief by accumulating different dry sift over time.
Bubble hash, also called ice-water hash, is made by agitating the buds in ice water to separate the trichomes which are then collected. The cannabinoids are easily collected because they are lipophilic and will not dissolve in the water.
A rosin press is used to make this amber colored sappy extract that has become very popular in the recent past. At home, a hair dryer can be used to make rosin. Cannabis flower or trim is placed between sheets of paper which are then subjected to high heat and temperature. An amber-colored resin will be released which quickly solidifies into an extract with shatter-like consistency.
- Chromatography and remediation
Remediation entails removing undesirable compounds from a cannabis or hemp extract. High Pressure Liquid Chromatography (HPLC) is commonly used for remediation. In this method, the analyte is dissolved in a solution (mobile phase) and taken down a pressurized column. As it passes through the column it interacts with different components known as the stationary phase. A diode reader at the end of the column is used to capture the data which can be interpreted by a chemist.
HPLC has several benefits. It can be used to determine the age and quality of the biomass. It can also be used for the remediation of THC from hemp or other unwanted compounds.
- Other extraction methods
Cannabis extraction is a field that is growing rapidly and newer methods of extraction are being introduced to the market by the day. Below are two extraction methods that are bound to cause major changes in the market if they will be adopted.
The name “sonication” has something to do with sound waves.
Sonication, also called ultra-sonic extraction, involves the use of sound waves to extract cannabinoids from cannabis. In this method, sound energy is applied to the biomass through a probe to agitate the particles. Hence, it can be considered as a form of mechanical extraction. Ultrasonic waves (up to 20,000 cycles per second) are usually used to cause agitation that break down cell walls to release cannabinoids.
Microwave assisted extraction
As the name suggests, this method uses continuous flow microwave extraction with high throughputs above 200kg/h of biomass input. The biomass is mixed with an extraction solvent and pushed through the continuous flow microwave-assisted extractor which is then heated. The extract is then separated and purged. This method has a high efficiency but has a high startup cost.
- Is it Legal to Extract Oils from Cannabis?
Across the US, it is legal to extract CBD from hemp, thanks to the passage of the 2018 Farm Bill that legalized hemp at a federal level. In this case, hemp refers to cannabis sativa that contains less than 0.3% THC which is the psychoactive cannabinoid.
However, cannabis is not legal at a federal level. Therefore, it is important to check with your relevant state laws to know if you can extract cannabis oil legally in your jurisdiction.
- Opportunities in the cannabis extraction market
The cannabis market is growing exponentially with an estimated compound annual growth rate (CAGR) of 14% for the next seven years. This can be attributed to several factors, but importantly, the legalization of cannabis for medicinal and recreational use in different parts of the world.
Science is also a big driver of this positive shift; the potential of cannabinoid-based medicine has increased the demand for cannabis.
Cannabis has shown potential in the treatment of chronic illnesses such as Alzheimer’s, Parkinson’s, and cancer.
There is huge potential in extracting some of the popular cannabinoids such as THC, CBD, CBN, CBG, THCA, and CBC.
Most recently, demand for the psychoactive cannabinoid called delta-8 has skyrocketed. However, this may be a temporary opportunity seeing that it might just be a matter of time before the FDA bans its use. Delta-8, like THC, is psychoactive and able to cause euphoria. Consequently, it is likely to be considered as illegal as its counterpart THC under federal law.
Previously, there was a lot of buzz around CBG, CBC, and THCA.
It is important to keep your ears on the ground for the “trending” cannabinoid as this may provide short-term opportunities. However, it may be more profitable to stick with the all-season cannabinoids such as CBD and THC.
Keeping abreast of the latest cannabinoid research might also be helpful. This will help you to dive in before the rest of the market does. When the market is saturated and prices are pushed down, profit-making may seem like a wild goose chase.