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What Is Solvent Extraction?
Like all plants, cannabis produces an essential oil. However, this essential oil cannot simply be melted off in a tea or washed away because oil and water do not mix. Therefore, a solvent is needed to separate the essential oil from plant matter. This solvent allows extractors to concentrate cannabis
resin into a product of its own. This oil concentrate can be used by itself or infused into other goods,
like medicine, foods and topicals.
Professional extractors use many different solvents to concentrate the essential oil of cannabis.
Ethanol, butane, and CO2 are the most common solvents used by extractors. These solvents can be
used to extract resin from psychoactive cannabis varieties and non-intoxicating hemp cultivars alike.
Yet not all solvents and extraction methods are created equal. Some, like ethanol and CO2, are safer for consumers and processors alike.
What Is Ethanol Extraction?
Simply, ethanol is alcohol. In ethanol extraction, the alcohol is used as a solvent. Unlike other solvents, like butane, ethanol is considered a safe and clean solvent that poses little risk of toxicity. Apart from solventless extractions, ethanol is considered one of the safest solvents to use in consumer goods.
While all commercial extractions must undergo lab testing to ensure that unsafe levels of residual
solvent are not present, ethanol easily evaporates and poses little risk to human health. That is why
ethanol is an often use as a solvent in pharmaceutical applications.
As a solvent, ethanol is highly efficient. Alcohols are polar in nature, allowing ethanol to form bonds
with both water-soluble and fat-soluble plant compounds alike. This quality makes the solvent an
excellent choice for those seeking a full-spectrum extract. Unlike other solvents, ethanol is not quite
as picky about what it pulls away from plant material. Though, professional equipment allows
extractors to further purify their ethanol concentrates.
Ethanol is also often mixed with other solvents to produce extracts with specific properties. For
example, the alcohol is frequently used at the end of a BHO or CO2 cycle to “winterize” the product by pulling out unwanted waxes. The final product will often be more translucent, with a light amber
If ethanol is used in a sub-zero extraction, which means the ethanol temperature is at about -40°C, the solvent won’t attract waxes, fats, chlorophyll, or any other unwanted stuff from the biomass. There is no further need of winterization which makes it a highly efficient process.
How Does Ethanol Extraction Work?
Normally those process machines consist of a big vessel, where the biomass gets in contact with the
ethanol. The ethanol should have a minimum purity of 96 %vol. After a certain time, the fresh extract
is sucked of from the biomass and is stored separately. If a winterization is needed, this will come
directly after extraction. The last step is to evaporate the ethanol from the extract, which is normally
done in a separate machine or vessel.
At sub-zero temperatures, the ethanol is cooled down first, and then brought in contact with the
biomass. The contact time at sub-zero is reduced to a minimum, usually 3 to 5 minutes, to decrease
the attraction of unwanted material. The final product is often syrupy in texture. Ethanol extractions
produced with professional extraction machinery and properly processed will also be light to dark
amber in coloration.
What Is CO2 Extraction?
CO2 is carbon dioxide, which can be used in extraction processes when exposed to the correct
temperature and pressure conditions. Like ethanol extraction, CO2 extraction is considered one of the safest forms of extraction possible. CO2 products pose little risk of toxicity to consumers, which is perhaps one of the reasons that vapor cartridges filled with CO2-extracted oils have become so wide-spread. Extractions made with CO2 tend to be light to dark amber in color and have a honey-like consistency.
Unlike ethanol, however, CO2 is very picky. While ethanol tends to easily dissolve both water-soluble
and fat-soluble molecules, CO2 fails to extract much of the beneficial phytochemicals present in
In fact, a study published by Planta Medica in early 2018 found that CO2 extraction drastically changed the chemical composition of cannabis strains. Compared with dried flower, CO2 extracts eliminated many of the subtle flavor and aroma molecules that provide nuance and subtlety to the experiential effects of different cultivars.
When compared to the strain that went into the extraction process, the final result produced a
significantly different product. Yet, for consumers hoping for a product that is as pure as possible, CO2 extraction is just a few steps down from an isolate. An isolate is purified CBD or THC on its own, separated from all other compounds.
How Does CO2 Extraction Work?
Many CO2 extractors use the supercritical CO2 method to safely extract cannabis resins. The CO2,
which is normally a gas, is cooled and pressurized until it reaches a state that is somewhere between a gas and a liquid. This odd phase of matter is called a supercritical state. This in-between phase allows CO2 to be passed through plant material as a gas. However, because it also features many of the physical properties of a liquid, CO2 is often a successful extraction method.
The machinery used to process CO2 extractions often features three distinct chambers, one which
pressurizes and chills CO2, one for the plant material, and one which Professional extractors use
machinery that creates a closed-loop system, which allows the CO2 to be recaptured at the end of the process. Like ethanol, the ability to recapture and reuse CO2 makes this type of extraction clean and efficient.
Ethanol Extraction vs. CO2 Extraction
Ethanol Extraction is not only less of a drain on economic resources but is safer when it comes to lab
safety than combustible CO2. While no extraction method is perfect, ethanol is one of the best and
safest for drawing out the subtle flavors, aromas, and synergistic compounds that are found in the
cannabis plant. These compounds work with one another to amplify the beneficial compounds of hemp extracts. For this reason, ethanol extractions may be among the best for those hoping to use hemp oil for health and wellness purposes.
Even ethanol is not without its criticisms, however, what some consider a downfall to ethanol
extraction is also the solvent’s primary benefit. Since ethanol is polar, it acts as a generalized solvent
rather than a selective one. As a generalized solvent, ethanol is capable of extracting more
phytochemicals than other solvents. This means that an ethanol-based extraction will have a greater
nutrient-density when compared with other extractions.
As mentioned above, CO2’s pickier nature can miss out on some of the potentially nutritious
phytochemicals during the extraction process. Many of the beneficial flavonoids and other
phytochemicals in the cannabis plant are water-soluble. In order to effectively extract these
micronutrients, a polar solvent like ethanol is needed.
CO2 extracts usually have a high share of fats waxes in it, which leads to the necessity of doing
winterization or dewaxing the extract. The common technology for winterization is to resolve the
extract in ethanol, cool it down, in suck the extract through a filter. Of course, the ethanol must be
evaporated after winterization. So, those who want to avoid ethanol as a solvent and use CO2 instead will need ethanol in downstream. That is why most professional extractors tend to use ethanol, even sub-zero ethanol, as a solvent to get a highly efficient process.
Ethanol is a solvent that is made due to plant fermentation and is a by-product of plants themselves.
It is a solvent made by the plants for the plants. Alcohol is also the only solvent that maintains the
original chemical ratios contained in the plant. This is due to alcohol extracting both water soluble and oil soluble components. In other words, ethanol dissolves both water and oil soluble chemicals found in the plant while carbon dioxide can only dissolve the oil-soluble chemicals.
None of this is to say that CO2 extraction is without its uses. Each method has their benefits and
drawbacks. Using carbon dioxide can be an excellent way to extract nutrients from the cannabis plant and shouldn’t be overlooked. It’s simply that ethanol can be more efficient.
Extraction Technology – Overview
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