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EXTRACTION is the first mandatory step. By using a suitable solvent the cannabinoids and terpenes can be „washed“ out of the dry plant material.
The most common solvents are:
These three solvents are different in their selectivity and all of them got their specific pros and cons:
1. Supercritical Carbon Dioxide Fluid Extraction
Supercritical Carbon Dioxide is a form of CO₂ where pressure and temperature are increased beyond the critical point (30.98°C for temperature and 73.75 bar for pressure). By adjusting pressure and temperature, specific terpenes and cannabinoids can be targeted, thus producing extracts with with a complete terpene profile is possible.
2. Liquefied Hydrocarbon Extraction
Liquefied hydrocarbons, such as butane and propane, are fast and efficient solvents. But due to the flammability of hydrocarbons, attention must be paid. This method is mainly used for the small scale production of high quality THC (BHO) and not economic for hemp processing.
3. Ethanol Solvent Extraction
The ethanol method is a very simple and effective way of extraction. Due to the high polarity of ethanol a high efficiency is given and no pressurization (like for CO₂ and butane/propane) is needed. This allows an economical upscaling and makes Ethanol the number one choice for hemp processing.
The extraction can be performed with warm or cold (cryo) ethanol. While warm ethanol also extracts unwanted components, like plant lipids, fats, waxes and chlorophyll, the cryo-ethanol-method at temperatures below -20°C is very selective for cannabinoids. The low temperature decreases the solubility of unwanted components and a separate winterization step, which is needed for CO₂ and liquefied hydrocarbon extractions, is not required.
High Potency material vs. Hemp:
While high-potency material can be extracted with all three methods, the hemp industry with low potency outdoor grown plants (common in Europe) is limited to the ethanol extraction. Due to the very high amount of biomass required to extract a commercial useful yield of CBD, the required amount of gases and the requirement of large scale pressure proof equipment would be uneconomical. The deep cold (cryo) ethanol extraction is mostly recommended to reduce the amount of unwanted extracted material (wax, chlorophyll, Lipides, fat etc.). The extraction of low potency material (~2-5% CBD) with warm ethanol is not economical: The ratio between cannabinoids and unwanted components would be worse than 1:10 and a complex winterization would be required, where also all ethanol based solution would be needed to be cooled down to ≤-20 °C. Due to this, a direct cryo-extraction is the most common and most economical way for hemp processing.
A perfect solution for this scale, including all required GMP and ATEX conformity, is our Cryo-Ethanol-Extraction, which is available in two different sizes.
The winterization is required to remove unwanted lipids, fats and waxes out of the cannabis extract. The crude is soluted in ethanol (typical ratio between 1:2 and 1:10) and cooled down to below -20°C. At this temperature the unwanted components get solidified and can be filtered out. This process is done stepwise, starting with a coarse filter (20 μm) to collect remaining plant material, down to a very fine filter material (<1 μm) to separate all lipids and waxes.
Due to the same boiling range of cannabinoids and waxes, it is not possible to separate them during the distillation process.
In the CO₂ and hydrocarbon extraction, the solvent itself evaporates out easily under atmospheric conditions and most extraction systems have a built-in compressor to recycle the gases in a closed loop system.
However, also for these methods a mixture with ethanol (typically 10:1) is required for the mandatory winterization process and the ethanol needs to be removed prior to the winterization.
This process step can be performed with for example the PILODIST PD45SRD.
In the Cryo-Ethanol extraction the ratio of crude to solvent is much higher and can reach up to 1:100, which requires a solvent (ethanol) recovery unit with a much higher throughput than an ethanol recovery system for high-potency extraction.
Such a large scale ethanol recovery is directly integrated in our Cryo-Ethanol-Extraction.
In the plant material the cannabinoids are present in a form of carbon-acids, which are called THCa and CBDa. These acids are not activated and the decarboxylation process is required to transform them into the active structures of THC and CBD. This is achieved by heating, which results in a huge amount of CO2 escaping during the conversion process. Without a full decarboxylation a vacuum distillation step is impossible, as the CO2 will escape during the heating process and break the vacuum required for a heat sensitive molecular distillation.
The decarboxilation can be performed in stand-alone reactor systems or as an additional feature of PILODIST PD45SRD ethanol recovery system.
The extract (crude) contains a mixture of components besides the pure cannabinoids. Some of them, like terpenes and oils exhibit a lower boiling point and some (the tar like residue) higher boiling points. In order to isolate the desired cannabinoids from the unwanted side products a distillation process is required. Due to the high heat sensitivity of botanical products, a vacuum distillation is required to lower the boiling points below 180°C. The wiped/rolled thin-film molecular distillation is the most common and preferential way to prevent thermal degradation and to achieve high throughputs.
This distillation process needs to be performed in two passes.
First pass:
The first pass is performed at a moderate vacuum (~1 mbar/Torr) to get the lighter components (oils, terpenes) out as a distillate fraction, which condenses at the cooling finger of the still, while the residue fraction contains the cannabinoids and the tar-like waste.
The possible working pressure in this first pass is correlated on the boiling range of the crude. Depending on the method of extraction, different terpenes are extracted and also an incomplete solvent recovery and/or decarboxylation can result in an incondensable vapor load, which prevents a lower operation pressure.
Second pass:
After the removal of the light ends, the cannabinoids themselves can be distilled out of the remaining crude. This step is performed at the highest possible vacuum, which is typically in a range of 1×10-2 Torr to 1×10-4 Torr abs. to evaporate all cannabinoids, while keeping the system temperature below the critical value of 180°C.
The PILODIST Molecular Distillation Systems are tailor made for this application. Due to the GMP availability and an unique upgrade concept the system can “grow“ according to the facility’s needs.
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