Cannabis extraction holds a place of great importance in the marijuana industry. With the increased demand for CBD and THC infused goods as well as full spectrum products, the extraction process holds an integral place in marijuana business. The medical cannabis industry also depends on quality extraction processes to better be able to determine what dosages work for their patients.
Whole plant extracts have led the market to develop THC and CBD infused vape oils and edibles in the medical and recreational markets, many of them full spectrum products meaning they contain the entourage of synergistic chemicals from the cannabis plant. The cannabis plant contains over 100 cannabinoids, 8 of which are being studied for potential medical use, 140 different terpenes and over 500 bioactive chemicals. Being precise in extraction is a valuable quality assurance measure.
Initial Steps in Extraction
A critical step in the extraction process is decarboxylation which is necessary to activate the THC. This step involves the removal of a carboxyl group in the acid precursors THCa and CBDa resulting in THC and CBD.
The method of extraction determines which type if any of post-processing that may be required. Winterization is a step that often follows solvent based extractions for the purposes of achieving purity. Winterization involves dissolving extracts in cold ethanol to separate the lipids and waxes. Then the ethanol is boiled off leaving only the oil.
Three Major Forms of Cannabis Extraction
Previously, options for cannabis extraction were pretty limited. For thousands of years hash was made by hand rubbing or sieve rubbing dried cannabis plants to form blocks of sticky resin a process now aided by what we call high pressure rosin compression machinery.
3 Most Popular Cannabis Extraction Techniques
Methods used for extraction of cannabis chemicals are varied as to temperature and pressure relying on mechanical force to basically squeeze out the desired cannabis chemicals. Other techniques rely on solvents to pick up and transport the cannabis chemicals to another solution which is then processed to remove the solvent.
The 3 extraction techniques most commonly used include alcohol extraction, hydrocarbon extraction and supercritical CO2 extraction methods. Other newer methods have recently landed on the forefront of technology including microwave assisted extraction, ultrasound assisted extraction and hydrodynamic extraction.
Alcohol Extraction
Being one of the most efficient methods it is known for being able to process a large amount of flower in hot, cold, or temperate climates.
The Soxihet extraction technique is used for hot alcohol extraction. This method cycles hot alcohol through the intact cannabis flower denaturing it of all of its cannabinoids and terpenes from the flower in the process. The downside to this method is it is difficult to work with larger batches and often than not too much chlorophyll is extracted along with plant waxes. Cold alcohol extraction helps to avoid this problem as it is harder for the polar plant waxes and chlorophyll to dissolve in the alcohol solvent.
Room temperature alcohol extraction seems to be better than either hot or cold. It is like a teacup situation where the cannabis flower is submerged at room temperature in a vat of alcohol and once the cannabis “teabag” is removed the resulting oil solution made up of cannabis can be gradually heated to remove the alcohol solvent and leave behind a high purity cannabis oil that contains the most common cannabinoids.
Hydrocarbon Extraction
This type of extraction usually involves butane or propane, a process said to capture a greater percentage of the terpenes. The only problem is, extraction techniques involving hydrocarbons are outlawed in Canada and in some counties of the U.S. so knowing your regulations is paramount.
The extraction occurs at a low boiling point. The process begins with cannabis and liquid butane in a pressurized and heated system. Using evaporation under a vacuum you can take out the butane solvent turning the butane from liquid to a vapor making it easier to remove.
This extract is then known as shatter which is a clear material that contains THC, CBD and other chemicals including terpenes.
It is still difficult to deal with large single batches of flower with this method, but its efficiency makes it an option for large scale operations.
Supercritical CO2 Extraction
While somewhat of a newcomer on the scene, it is a much-preferred method of extraction for many. While the method has been around for decades, it has just recently gotten around to being used for cannabis extraction.
When heated to 31.10 C (critical temperature) and at 1071 psi (critical pressure) it has the properties of both a gas and a liquid. It becomes what is known as a supercritical liquid. Supercritical liquids can pass through solids and make excellent solvents. It is able to extract the desirable components of cannabis while leaving the chlorophyll out.
The method involves using specialized pressure and temperature control equipment to turn the gaseous CO2 into a supercritical fluid. When this supercritical fluid is passed over cannabis flower the fluid can easily extract plant oils and waxes from the cannabis plant. Supercritical extraction also kills off bacteria, mold and fungi, contaminants you don’t want in your extract especially for those with compromised immune systems.
After the cannabis components are extracted the supercritical CO2 is funneled into a condenser that returns the CO2 back into liquid that can be filtered and reused. So, little reagent is used so there are no residual solvents to be concerned about.
The process is under low pressure for long periods of time and starts with high quality flower. Hardly any, if any at all, post-processing is needed the end product is so pure.
While the capital investment for this method is initially high, it is thought that the quality of the process makes the cost an acceptable expense.
New Extraction Advances
Other extraction methods exist, each with its own pros and cons, and are used in extraction. These are:
Microwave-Assisted Extraction
Providing a source of instant heat that is absorbed in waves rather than from inside out or vice versa, the heat travels over the cannabis depositing energy into residual water spaces and pressure is created. This is a pressure driven process that is instantaneous.
Compared to solvent extractions the advantages are:
- Improved purity of product
- Reduced processing costs
- Fast extraction rates with reduced energy and solvent usage
Ultrasound-Assisted Extraction
This process can be used with alcohol extraction to enhance its effectiveness. Essentially, it is the use of sound energy to form microbubbles in the solvent medium. The microbubbles will fold violently within a noticeably short amount of time forming little localized hotspots that can reach temperature of around 5000 Kelvin and pressures above 500 bar. The extreme conditions create strong hydro-mechanical shear forces which can change the cell walls of the cannabis material allowing the plants natural oils to dissolve in the solvent more readily.
This technique has not been widely adapted by the cannabis industry although it is used in nutraceutical extraction quite frequently.
Hydrodynamic Extraction
This process uses a combination of temperature, pressure and ultrasonication to create full spectrum cannabis extracts from whole flower. In this process the flower is frozen and then broken down by ultrasonification and hydrodynamic forces. The result is a solution of cannabinoids, terpenes and other oils from the cannabis plant stabilized in an aqueous phase. This solution is then separated by centrifuge followed by a low temperature vacuum distillation and drying to turn the nanoemulsion into a highly bioavailable extract.
Solvent-free Extracts
Basic techniques have existed for hundreds of years for processing and extracting cannabis, but the methods have been more hands-on. Kief, for example, can be separated from the cannabis buds simply by grinding and sieving.
These crystal formations make up what is called trichomes which are where the THC is made in the cannabis plant. Cannabis trichomes are present only on the female flowers of the cannabis plant. The kief must be decarboxylated to become active and simple heating can accomplish this. Kief is added to other products to increase potency or consumed on its own.
Traditional hash is another example of a solvent free cannabis product. To make hash you take frozen cannabis buds and break them into smaller parts over a screen whereby the trichomes are separated from the cannabis and are pressed into blocks.
Rosin has also become popular over the years and is produced from flowers, hash or kief by applying heat and pressure to the product you wish to extract from and you get a product similar to what you would get in a butane extracted process. It is a translucent substance with a sap like consistency. Enthusiastic users have used hair straighteners, some baking parchment a collection tool and some heatproof gloves to complete the process. Rosin pressing machines can be obtained from this site
Assistance in designing your extraction method can be greatly facilitated by consultation with experts. Expert consultation can be found by visiting this website and choosing from one of the companies listed to help you in extraction design.
