A Cool Process

Cryogenics involves the creation of extreme low temperatures [1]. It also includes the study of material properties at these temperatures. Intensely low temperatures radically alter a material’s thermal and electric conductivity, strength, and ductility. Materials at cryogenic temperatures are in a highly ordered state [2]!

In the cryogenic extraction of cannabis, ethanol is cooled down to very low temperatures. Cryogenic cooling is controlled and fast, allowing process standardization necessary for Good Manufacturing Practice (GMP) compliance [3].

Ethanol is polar by nature. Cryogenic ethanol dissolves minimal chlorophyll and polar waxes (the undesirables) from cannabis. Ethanol naturally dissolves hydrophilic and lipophilic materials. Hydrophilic materials tend to dissolve in, blend with, or wetted by water. Lipophilic materials dissolve in or combine with fats or lipids [4].

 

Extraction

 

The Process

Commonly called Cold Ethanol Extraction, the cryogenic extraction process is inherently optimized [5]. This is because it maximizes extraction of the required molecules from the raw material while avoiding separation of unwanted molecules [6]. As a result, it takes care of both – purity of product and producer’s profits [6].

Generally speaking, the Cryo Ethanol Process operates as follows [7]:

  • Chilling: Ethanol is chilled to –400 At this temperature, it is called cryogenic ethanol or cryo ethanol.
  • Extraction: Finely milled raw material (cannabis for example) is loaded into the extractor. Cryo ethanol is introduced into the extractor and circulated repeatedly through the raw material to separate the target molecules (cannabinoids in this case).
  • Centrifugation: Separates the solid biomass from the ethanol (which also contains the dissolved target molecules).
  • Filtration: Eliminates tiny biomass pieces from the ethanol solution.
  • Distillation: Isolates ethanol from the target molecules. Heating the filtered solution evaporates the ethanol, which is condensed subsequently. What is left behind after ethanol evaporates is highly pure cannabis oil.

 

The Science of Cryogenics

Moving molecules generate heat. Such heat energy is minimal at the absolute zero of temperature i.e. at 00K (Kelvin) or –2730C, where molecular motion is negligible [8]. As temperature drops towards the absolute zero, molecular motion slows down. This minimizes [8] the heat and brings in the mentioned orderly state [2].

Cryogenics employs the Kelvin and Rankine scales as these are absolute scales with positive values only [9]. Resistance Temperature Detectors (RTDs) measure temperatures up to 300K (-2430C). Silicon Diodes take over this responsibility for temperatures below 300K [9].

 

Extraction

 

Why Cryogenic Extraction for Cannabis?

Up scaling the cold ethanol extraction process is cost-efficient [6]. In the context of cannabis extraction, this parameter assumes extraordinary importance. Governments over the world are legalizing cannabis in recognition of its fantastic health effects. It is only a matter of time before the demand for cannabis products scales peak after peak.

Even the United Nations Commission on Narcotic Drugs (CND) declassified cannabis resin and cannabis from Schedule IV of its Single Convention on Narcotic Drugs, 1961. The December 2020 CND resolution is most likely to trigger rapid growth of the cannabis industry. Schedule IV of the 1961 Convention lists the most lethal drugs [10].

Benefits of cryogenic ethanol extraction:

  • Scalable: Equipment is available in numerous sizes for up scaling the extraction plant [7]. Ethanol is cheaper than hydrocarbons and does not require special, expensive methods for storage. Scalability is important because success at one level usually makes producers jump to higher levels of production.
  • Speed: By eliminating the post processing procedure of Winterization, cryogenic ethanol extraction substantially reduces extraction time [7].
    The quantity of waxes, fats, and lipids drawn out of the cannabis raw material at –400C is negligible [11]. This minimizes the required post extraction procedures, which eliminate these undesirables. Winterization is employed to remove these impurities but is not required after cryo ethanol extraction [12] [13].
  • Safe: High pressures are not involved in the process. Besides, the higher boiling point of ethanol makes it safer than butane and demands less stringent storage requirements [7].
  • Economical: Cheaper than butane, the less rigorous safety and storage regulations cut down process expenses and licensing requirements.

 

Comparative Analysis

Cannabis contains numerous cannabinoids, cannabidiol (CBD) being the most desired with its countless medical benefits. Tetrahydrocannabinol (THC) also possesses some medicinal value, but gets the user “high” i.e. intoxicated. Besides, THC’s persistent consumption attracts side effects. CBD neither intoxicates nor, when acting alone, produces side effects [14].

Cryogenic Ethanol Extraction CO2 Supercritical Fluids Extraction (SCFE) Hydrocarbon Extraction Ethanol Extraction
Cannabinoids Cannabinoids Cannabinoids Cannabinoids: CBD, THC, CBG
Terpenes Full Terpene Profile Terpenoids

(mono terpenoids and mono terpenes)

Waxes Plant Waxes Plant Waxes
Pigments Pigments Plant Pigments: Carotenoids, Chlorophyll
Unknown Compounds Aromatic Hydrocarbons Unknown Compounds

Table: Which Method Extracts What from Cannabis? [15]

 

Legally, cannabis with 0.3% (dry weight) or less THC is hemp and that with over 0.3% THC is marijuana [14]. Hemp is legal in many parts of the world, marijuana is not [16]. Post extraction processes are commonly employed to:

  • Maximize cannabinoid and particularly CBD content.
  • Retain terpenes and flavonoids, which impart aroma and flavor to hemp oil apart from fortifying its medicinal properties [17]. Ironically, however, there is collateral damage involved as post extraction also ends up removing some desired terpenes and flavonoids [15].
  • Eliminate unwanted by-products.
  • Remove all traces of THC via THC remediation (sometimes).

 

Here is a comparison of the common methods of cannabis extraction:

  • Ethanol Extraction: Optimized for cannabinoid extraction, the method does not substantially draw out flavonoids and terpenoids. Warm temperature ethanol extraction decarboxylates tetrahydrocannabinolic acid (THCA) to THC [15]. This is a welcome reaction for decarboxylation is among the post extraction processes.
  • Hydrocarbon Extraction: Is fast and provides highly flavored and concentrated cannabinoids. This is an old, low temperature, and low pressure technique delivering extracts with more than 75% cannabinoids [15].
    Considerable post extraction processing is necessary to separate the extract from the hydrocarbon solvent. And because the solvents are inflammable, equipment for storage and extraction has to comply with stringent safety norms. This adds to the expenses and complicates scalability [15].
  • Carbon dioxide (CO2) Supercritical Fluid Extraction: Is a selective process and extracts very little of the unwanted elements. Yet, post extraction processes are necessary to refined final product.
  • Cryogenic Ethanol Extraction: Ultra low temperatures in the process leave pigments and waxes out of the final extract. With some decarboxylation, the obtained extract is loaded with cannabinoids.

 

Extraction

 

Finally

What tips the scales in favor of cryogenic ethanol extraction is its scalability, given the expected spurt in demand for pure cannabis products. Its capacity to selectively isolate cannabinoids from cannabis plant material too is valuable.

 

Buffalo Extraction Systems (BES) offers scalable, automated, and GMP-compliant cryogenic ethanol extraction plants of 5 / 20/ 50 / 100 kg per batch capacity. With a 20 minute batch duration, we provide a 120 to 2400 per 8 hours throughput. Our equipment comes with a proprietary tablet APP and recovers 98% of the used ethanol.

Write to us at info@buffaloextracts.com to know more on our intelligent systems and committed workforce that guide you through the nuts and bolts of cryogenic ethanol extraction.


 

References

  1. Gaslab.com. “What is Cryogenics?”
  2. “Cryogenics.”
  3. Timothy Lebrecht et al. “Cryogenic Solutions for Compliant Industrial Hemp Processing.” Process Cooling.
  4. Botanical Solutions. “The Advantages of Cryogenic Ethanol Extraction.”.
  5. Root Sciences. “Ethanol Extraction System.”
  6. Colin Daracel. “Cryogenic Ethanol Extraction Equipment for Extracting Cannabis Oil.” Maratek.
  7. Precision Extraction Solutions. “What is Cryogenic Ethanol Extraction & What Equipment Do You Need?”
  8. “Absolute Zero.”
  9. Annie Marie Helmenstine. “Understanding the Concept of Cryogenics.”
  10. Om Marathe. “Explained: The Implications as UN Removes Cannabis from its ‘Most Dangerous Drug’ Category.” Indian Express.
  11. “Automating the Cannabis Oil Extraction Process.”
  12. “A Comparison of Hemp Oil Refinement Methods.”
  13. Apeks Supercritical. “How to Extract CBD Oil – The Extraction Process & How to Make CBD Oil.”
  14. Aaron Cadena. “Hemp Vs Marijuana: The Difference Explained (2020 Update).”
  15. Lo Friesen. “Exploring the Chemical Makeup of Cannabis Extract by Method.” Cannabis Science & Technology.
  16. Plain Jane Blog. “Legal Status of CBD Around the World.”
  17. Canna Insider. “Guide: Flavonoids, Terpenes, and Cannabinoids.”