Ethanol has a long history of extracting oil from plant materials for therapeutic use. In today’s highly competitive marijuana extraction sector, extraction artists have a wide range of extraction solvents to choose from such as carbon dioxide, light hydrocarbons (propane and butane), and ethanol. These solvents are used to extract the cannabinoids and terpenes from the cannabis or hemp resin.
What Is Ethanol Extraction?
Ethanol is more common than you think. Ethanol can be found in grain alcohol made by fermenting plant sugars from agricultural crops. Ethanol (C2H5OH), also known as ethyl alcohol, is a colorless and flammable liquid that can produce intoxication, be used for fuel, and also be used as a solvent. Ethanol can be fermented from different crops, but corn is the main source of ethanol in the U.S.
Ethanol extraction can be performed under warm or cold temperatures. Generally, raw and ground-up cannabis material (dry or frozen) is soaked in pre-chilled ethanol for a certain amount of time to separate the plant’s trichomes from the plant matter. Warm ethanol extraction has been a staple in amateur home extractions. For larger batches, room temperature or cooled ethanol can improve the quality of cannabinoids and terpenes in cannabis and hemp extraction.
After the initial extraction process using food grade ethanol, the solution is filtered and the ethanol is purged from the extract. Post-processing techniques gently remove ethanol from the extracts through evaporation. Ethanol may be removed with rotary evaporators, falling film evaporators, or a vacuum distillation system.
Winterization is a term used to describe the process of removing impurities such as plant lipids, chlorophyll, waxes, and fats from the oil. Chilling the oil and ethanol solution can cause these undesirable compounds to separate (precipitate) and rise to the top for easier removal. The cooling process can be performed in freezers, cold rooms, or other cooling equipment.
Keep in mind, ethanol has a higher boiling point than butane or propane. Because of its relatively higher boiling point, many of the terpenes that give cannabis the desirable flavors and aromas that many consumers enjoy, are lost in the ethanol extraction process. The inevitable loss in terpenes from the ethanol process also diminishes the entourage effect of the final ethanol extract product when compared to BHO extraction. Regardless of ethanol’s weaknesses, large-scale throughput and financing can easily overcome equipment limitations.
Ethanol extracts can also undergo a final polishing phase where adsorbents can be used to lighten the oil’s hue and improve the translucence of the extract. Popular adsorbents such as activated charcoal and bleaching clays can improve not only the color but also the quality of ethanol concentrates.
The residual ethanol is evaporated, condensed, and reused in the closed-loop extraction system to increase cost-efficiency and throughput. All of these operations take place in a lab-grade facility with adequate ventilation and storage areas.
Why You Should Choose Ethanol Extraction Over CO2?
Every extraction company favors one solvent over another for various reasons. Butane is the most common solvent used for cannabis extraction and CO2 extraction has also been touted as safe and eco-friendly. Ethanol extraction, however, offers both safety and efficiency when extracting cannabis or hemp on a large scale.
For high-volume extractions, ethanol can be the most efficient at separating cannabis compounds from the plant matter. Ethanol is an extremely polar solvent that can bind to cannabinoids, terpenes, but also chlorophylls and other water-soluble undesirable compounds. Many terpene boiling points are about the same as ethanol’s boiling point, thereby, increasing the risk of terpene loss when removing the ethanol solvent.
Ethanol’s polarity problem can largely be overcome with chilled ethanol (-40ºC or below) to bypass most of the chlorophyll, lipid, and other unwanted compounds. Under the proper conditions, ethanol extraction can produce isolate or limited full-spectrum concentrates with cannabinoids, and some terpenes, flavonoids, and other therapeutic compounds.
Ethanol can be easy to scale because using this solvent becomes cost-effective at a higher volume (1,000 to 5,000 pounds per day) compared to CO2 extraction, for instance. As hemp farming heats up across the nation, growers and extractors are looking for the most versatile and cost-efficient to reap CBD for a variety of infused products, not just CBD flower.
Is Ethanol Safer?
Ethanol extraction is no safer than hydrocarbon and CO2 extraction, that is to say, all extraction methods are safe for production under the approved building requirements. In fact, the Food and Drug Administration (FDA) has classified ethanol as a Class 3 solvent with low toxicity. Ethanol is one of the safest solvents for food grade and pharmaceutical extraction processes.
In pharmaceutical manufacturing, residual ethanol below 0.5 percent or 5,000 parts per million (ppm) is considered generally safe. Some legal cannabis states, however, have enacted stricter cutoff residual solvent levels based on recommendations from the Occupational Safety and Health Administration (OSHA) and the National Institute for Occupational Safety and Health (NIOSH). Residual cutoff levels vary by state.
While ethanol extraction may not be any more dangerous to use than light hydrocarbon extraction or CO2 extraction, the building requirements for ethanol extraction are less stringent than hydrocarbon extraction approval. Jurisdictions are familiar with approving distilleries that use ethanol compared to approving propane and butane facilities that elicit negative images based on a lingering stigma from black market extractions.
On top of receiving quicker approval by local governments, storage limits for ethanol are much more lenient compared to other solvents. That means an extraction facility can store more ethanol in the facility and use large volumes of ethanol at one time for cannabis or hemp extraction. Storing large volumes of solvent can keep the continuous extraction going without missing a beat.
Ethanol extraction systems are the go-to solution for large-scale commercial operations that process a high volume of cannabis or hemp. Ethanol is fast, reliable, and efficient at extracting low to mid-quality oils from cannabis and hemp for companies looking to scale. With the proper ethanol extraction system, cannabis companies can process hundreds of pounds of material per hour and gain a competitive edge.