Qualitative and quantitative analysis of the cannabis plant shows it to possess over 113 functional cannabinoids, which are extracted industrially as extracts, concentrates, and oils. The world today is gradually coming to recognize the benefits of cannabis isolates and extracts, causing a rapid increase in its market value.
Did you know: All extracts are concentrates, but not all concentrates can be considered as extracts.
Cannabis extracts are isolates derived from their biomass via solvent-based processes. The solvent-based process makes use of volatile organic solvents in trichomes separation from the plant and is the majorly utilized technique for commercial extract production.
The combustible property of a vast majority of these solvents has marked the procedures as potentially dangerous unless carried out by professionals. The following techniques are utilized in extracts production for industrial raw materials and human consumption:
- Alcohol extraction technique
- Supercritical carbon dioxide extraction technique
- Hydrocarbon extraction technique
ALCOHOL EXTRACTION TECHNIQUE
In commercial cannabinoid extraction, there are two principal forms: warm and cold- temperature alcohol extraction. The warm alcohol extraction is commonly carried out via the Soxhlet technique, while the cold alcohol extraction uses cryogenic ethanol extraction systems.
The Soxhlet apparatus invented in 1879 by Franz von Soxhlet; works on the principle of sample-solvent polarity. It requires little modifications and control in its operation.
An appropriate solvent is pumped into the distillation flask by the pump. In the distillation flask, the solvent is heated with a heating element, after which it flows through the distillation arm into the thimble containing the biomass.
Simultaneously, the condenser unit made of two tubes: the solvent vapor tube and the solvent outlet tube, ensures the condensed solvent vapor drops into the thimble. After extraction, a mixture of extract and solvent flow to the Soxhlet extraction chamber – consists of a vessel that holds the mixture and the siphon tube from which the isolate is expelled.
Before expelling the isolate, the volatile solvent is vaporized by the rotary evaporators and returned to the distillation flask.
Note: In the selection of a Soxhlet extractor, its holding volume and capacity should be considered.
- Requires little mechanical know-how
- Effective extraction process
- Economically efficient due to solvent recycling
- Diminishes entourage effect
- For an efficient outcome, azeotropic mixtures should be used
*** Azeotropes are mixtures with a fixed boiling point which cannot be altered through simple distillation.
Cryogenic Ethanol Extraction Systems (CryoEXs)
The discovery of the CryoExs has brought the ethanol extraction technique to a brighter light of the best- of- both worlds: highly efficient extraction procedure to produce a full-spectrum product.
The solvent is cooled in the solvent storage with a cryogenic chiller before flowing into an extraction vessel holding the biomass. In the extraction vessel, the isolate is separated, and solvent/isolate solution filters through the tank into the sock filters for further purification. Finally, the mixture streams into the condenser, where the solvent is separated from the isolate via evaporation and reflux.
Tip: The extraction vessel can be connected to an integrated winterization system to avoid loss of CBD-content in a secondary winterization process
- Maximum uptime
- Maximizes output quality
- Easy scalability
SUPER-CRITICAL CO2 EXTRACTION
This is the extraction of cannabinoids with the aid of supercritical fluids. Most of these fluids are classified as Volatile Organic Compounds (VOCs), of which several are under tight regulations due to their detrimental effect on the ozone layer.
However, CO2 makes for an eco-friendly alternative to the hazardous VOCs because though it is a greenhouse gas, it can be recycled from and back to the atmosphere.
SUPERCRITICAL EXTRACTION VESSEL
The supercritical extraction vessel works on the combination of solvent, room temperature, and high pressure in extraction.
Before extraction, the pressure pump raises the solvent’s pressure to a level beyond its supercritical point, but just high enough to keep the biomass’ phytochemicals intact. The pre-heater simultaneously works with the vessel’s heater to ensure temperature regulation of the solvent (CO2).
Following solvent activation, it moves into the twin-batch extractor containing the biomass to separate the target isolate. The solvent-isolate mixture subsequently flows into the separator vessel, after cooling by the back-pressure regulator. At the separator vessel, the solvent is finally vaporized from the isolate by rotary evaporators.
Fun tip: A typical supercritical extraction vessel functions between the range of 1800psi and 5000psi.
- Inexpensive solvent
- Produces non-toxic isolate
- Less hazardous
- Expensive machinery
- Liable to the Joules-Thomson effect
- Slow extraction rates on less expensive machinery
It is the prevalent technique used in the commercial extraction of cannabinoids. It makes use of legalized hydrocarbons, commonly butane and propane as a solvent. Either hydrocarbon can be used independently or combined to provide a more efficient process. Though this process gives a pure output, the isolate can be further refined (if necessary) with other processes such as winterization.
Butane as a Solvent
- Class 2 flammable compound.
- Low boiling point (31.1®F)
Propane as a Solvent
- Relatively higher pressure to butane.
- Boiling point of -43.6®F; hence the high pressure (Pressure law)
***Pressure α Temperature
HYDROCARBON EXTRACTION MACHINE
The hydrocarbon extraction machine is a modern, safe, and economical system used in obtaining diverse forms of cannabis isolates.
The solvent is held in a pressurized recovery cylinder before flowing into the blasting chamber, where the target isolate is separated. After separation, the solvent-isolate mixture is collected by the collection vessel submerged in a warm water bath – contains a Class 1/ Division 1 immersion heater – to vaporize the solvent.
Following solvent vaporization, the molecular sieve separates residual moisture from the solvent, after which it is propelled by pneumatic pumps into an ice-submerged condensing coil to re-liquefy the vapor before its return to the recovery cylinder.
- Highly solvent versatility
- Relatively higher quantity and quality yield
- Better preservation of isolate’s properties
- Operates at relatively low pressures (≤300psi)
- Hydrocarbon-related health complications in industrial workers
- Highly hazardous process
A refinement technique majorly used in the removal of lipids from cannabis oil. It is secondarily employed in the extraction industry in isolates’ purification. However, it diminishes the entourage effect of the extract and is therefore not encouraged when looking to produce full-spectrum CBD. The winterization process operates on the principle of waxes crystallization.
The solvent-isolate mixture is cooled and frozen in/with a chilling structure or device. It is important to note that the temperature and length of cooling are dependent on the nature of the solvent and the primary extraction process.
The frozen mixture is then allowed to rise to a temperature high enough to melt the cannabis isolate but not the waxes. After melting, the mixture is passed over a filter/ Buchner funnel to separate the waxes from the dissolved oil and solvent. To finalize the process, the centrifugal evaporator separates the more volatile solvent from the cannabis oil via evaporation.
FACTORS TO CONSIDER WHEN SELECTING EXTRACTION TECHNIQUE
Choosing the most suitable extraction technique might be a little complicated, with some of the methods involving flammable solvents having their own safety concerns. During the purchase of extraction equipment, there are two common pitfalls most individuals fall into:
- Individuals who purchase without consulting a certified facility design team
- Individuals who buy without considering building and property design.
Therefore in selecting a suitable technique to be employed, the listed overall factors should be considered:
- Production goals and performance quality
- Extraction method to be used
- Overall budget (up-front and total)
- National safety standards compliance of equipment
- Building and property of operation
- Voltage and frequency standards of equipment
- Legislation of raw materials use