Alcohol extraction is a process designed to remove essential oils, fats, and other chemical compounds (like cannabinoids) from botanical material AKA plants. Any plants. But for our purposes, we’ll be discussing it in relation to the marijuana plant, of course.
There are quite a few different ways to perform an alcohol extraction but only a select few are effective in cannabis. Both the delicacy of cannabis terpenes and the unusual chemistry of the compounds people want to extract from cannabis limit extraction methods to three primary options: butane, supercritical CO2, and ethanol extraction.
Butane is popular for home users because it’s exceptional when it comes to selecting the active cannabinoids and terpenes required to make concentrates potent. Meanwhile, supercritical CO2 is popular in professional settings because it’s relatively cheap and safe, but purifying the extract takes longer than it does with butane. And finally, there’s ethanol, which we’ll be breaking down today.
Ethanol is relatively new to the cannabis extraction game so there’s a lot we still need to learn about it, but it’s gaining popularity as many argue that it could be the most effective and safest option we have—it might be able to select active cannabinoids and terpenes as well as butane does and it could be as safe to use as the CO2 method.
What to Look for in the Best Equipment
Ethanol extraction has only recently become popular due to a long-held belief that its molecular makeup diminishes its potential as a solvent. The polarized ends of ethanol molecules mean that they bond with different types of molecules on either side. Therefore, while ethanol can easily bring out cannbinoids and terpenes from plants, it also tends to draw unwanted molecules along with it, resulting in bitter, murky concentrates.
But with the rise of technology overall has also come a rise in ethanol extraction technologies. These days, there’s equipment on the market that will extract the vast majority of the chemicals you’re after while leaving the rest behind.
How Is Ethanol Used for Cannabis Extraction?
Ethanol extraction is a process in which waxes and lipids are separated for the most desirable products like terpenes, flavonoids, and cannabinoids. One reason that rotary evaporation is favorable for this technique is that the process is efficient with minimal labor. Because the ethanol can be reclaimed once extracted in a rotary evaporator, a manufacturer significantly reduces overhead costs.
Rotary Evaporator for Ethanol Extraction
Rotary evaporators are an important tool in laboratories around the world. While this technique has many different applications, this post regards the requirements of high purity ethanol and rotary evaporators for cannabinoid and terpene extraction. When combined with advanced solvent extraction and distillation processes, raw cannabis and crude cannabis yield shatter, THCA crystals or THCA-rich oral formulations. Final packaging includes many different forms of cannabis products including oils, tinctures, vaporizable concentrates, and edibles. Generally, rotary evaporators allow one of the most efficient and environmentally friendly ways of removing a volatile solvent from a non-volatile sample. Because the solvent is recoverable and reusable, it minimizes waste and also overhead expenditure.
How Does a Rotary Evaporator Work?
Also known as a “rotavap”, rotary evaporators use vacuum distillation to evaporate solvent from raw or processed materials. Commonly, a cold finger condenser connects a solvent trap which sits opposite of a flask on a rotator unit. Cold water in the condenser creates a zone of cooling. The boiling flask encourages evaporation, while the solvent trap is often cooled to discourage evaporation, therefore, trapping volatile compounds once they have begun to accumulate in a liquid phase.
Rotary Evaporator Vacuum Extraction
The introduction of a vacuum allows greater distillation capacity. Boiling points and system pressure are codependent. System pressure and water temperature is adjusted to provide the ideal boiling point temperature. As the temperature of a bath or pressure lowers, the evaporating solvent could exceed the condensation capacity of the evaporator, which causes “bumping” or unnecessary solvent loss.
Rotary evaporators allow many configurations depending on the use. A diagonal glass condenser is common for standard distillation of non-volatile substances. Vertical class condensers allow solvents with higher boiling points. For ethanol extraction with dry ice, a rotary evaporator with a cold finger glass condenser is ideal. A coldfinger configuration is common for the production of tinctures, yielding a thick concentrate that is considerably pure with relatively little solvent use.
What is the Advantage of Rotary Evaporation for Ethanol Extraction?
Rotary evaporators extract solvents at low temperatures with a high degree of repeatability and efficiency. The method of action decreases the pressure inside of the round bottom flask and increases the surface area through gentle rotation which improves process time. Gentle agitation promotes thorough evaporation and reduces the risk of bumping or flash boiling. The term “bumping”, refers to when a large pocket of solvent vapor forms rapidly and displaces the surrounding liquid.
Ethanol Winterization Process
Winterization is the process of removing waxes and lipids to create a consumer ready product. Waxes and lipids often produce unfavorable traits when heated and vaporized. Unless removed, consumption requires more heat, diminishes flavor, increases residual residues, and may cause harshness or irritation.
After winterization, the product is dissolved in ethanol and passes through vacuum lines into an evaporation chamber and on to a rotating flask which floats over a waterbath. The flask spins in order to create a thin film on the wall of the flask, causing slow and controlled precipitation of any volatile solvents.
When exposed to heat, this experiment shows that a mild water bath is favorable over intensive heating. For ethanol extraction, dry ice within the vertical “coldfinger” silo allows ultra-low temperatures which coax a complete removal of residual solvents from the target product. Room temperature evaporation often produces greater volumes of waxes and pigments. These byproducts may produce discoloration, harshness, or less palatable flavors, hence super-chilled extractions remain preferred.
