A Grower’s Guide to Ethanol Extraction in Cannabis

Cannabis extract
Photographer:
710 Labs

Introduction

As the cannabis industry has grown over the past few years, the market share attributed to cannabis extracts has begun to climb even faster. So far, Ethanol extraction is believed to be the best overall solvent for Cannabis extraction. 

Ethanol is one of three modes of extractions, the other two being butane extraction and supercritical CO2 extraction.

What is Ethanol?

Ethanol - also known as ethyl alcohol or grain alcohol - is a clear, colorless, and volatile flammable liquid, with a characteristic vinous odor and spicy taste.

Chances are, if you've consumed beer, wine, or spirits, you've likely had Ethanol in your system. Ethanol can also be used to make gasoline, beauty products, solvents, paints, and food additives. 

It "can be fermented from many starch sources, including corn, wheat, grain sorghum, barley, potatoes, and sugar crops. Because of the abundant supply of corn, most of the Ethanol made in the United States is from corn," the University of Illinois Extension explains.

Why Are People Doing Ethanol Extraction

The FDA classifies ethanol "Generally Regarded as Safe," meaning that it is safe for human consumption. As a result, it can be used as a food preservative and additive, found in some of your favorite beverages or snacks.

Ethanol extraction is considered one of the more simple extracting ways and is very common for DIY smokers in regards to extracting methods. 

Compared to other extraction methods like 'Butane' - one of the most common hydrocarbon solvents currently used in extraction - favored its non-polarity, which allows the extractor to capture the desired cannabinoids and terpenes from cannabis. Butane's low boiling point makes it easy to purge from the concentrate at the end of the extraction process, leaving a relatively pure byproduct behind. With that said, butane is highly combustible, and non-professional home butane extractors have been in some cases responsible for the stories of explosions.

Supercritical CO2, another extraction solvent, on the other hand, is praised for its relative safety of toxicity as well as environmental impact. That said, the lengthy purification process required to remove co-extracted constituents, such as waxes and plant fats, from the extracted product can take away from the final cannabinoid, and terpenoid profile of extracts yielded during supercritical CO2 extraction.

Capna Labs, a California-based extraction company founded in 2014, considered the benefits and drawbacks of several solvents, including butane and supercritical CO2, before choosing to work with Ethanol as their solvent choice. Galyuk. 

The Manufacturing Guidelines around Ethanol

The Food and Drug Administration (FDA) classifies Ethanol as a Class 3 solvent. In a pharmaceutical manufacturing processes, low risk for acute or chronic toxicity where the residual is less than 5,000 ppm or 0.5 percent. 

The FDA also implies that residual solvents in this category should be limited to 0.5 percent through rigorous quality assurance and quality control programs.

Despite those FDA guidelines, some states have adopted more conservative safety limits suggested by the Occupational Safety and Health Administration (OSHA) and the National Institute for Occupational Safety and Health (NIOSH). 

OSHA and NIOSH set the worker environmental exposure limit for Ethanol at 1,000 ppm of Total Weighted Average (TWA) over an eight-hour work shift, which means that some states allow only 0.1 percent residual ethanol in extracted products.

Numerous other considerations apply to the storage and use of Ethanol in manufacturing laboratories that could fill a column of their own; when it comes to storage, the maximum flammable cabinet storage is 60 gallons. The maximum storage permissible outside of a flammable cabinet or storage room is 25 gallons.

Different Outcomes

A few differences can happen between the outcomes of Ethanol extraction, which can be conducted under warm or cold conditions, is a single-stream process. 

An example of a warm ethanol extraction process is the Soxhlet technique. Ethanol is boiled, condensed, and cooled down - This warm Ethanol soaks the flower material in a quick process that leaves minimal residue - This technique is typically used to make smaller batches of cannabis oil. Additionally, this method can convert THCA into THC, which activates cannabis' chemical compounds. This may require more post-processing to remove unwanted matter.

Most ethanol extractors will use room temperature or cool conditions to extract specific cannabinoid acids like THCA and CBDA to make shatter crystals or other infused products. Using room and cool temperatures significantly reduce plant pigments and waxes in the final product and total cannabinoid recovery. Cooler temperatures, however, can be efficient at extracting THCA and CBDA because the temperatures preserve cannabinoids in their precursor acid forms.

The Procedure

Under room temperature or cool conditions, the process may look something like this:

  • Place the trimmings in the mason jar, and add the alcohol until the jar is almost full. 
  • Put the lid on the jar and shake for around a minute.
  • Then strain the mixture with the plant matter going into the plastic container. 
  • The alcohol mixture is then strained multiple times through paper filters into the coffee carafe and then left in the sun to evaporate.
  • The mix is then scraped from the Pyrex dish, cooked in the oven for several minutes, and then blended.

*You should freeze the cannabis trimmings or 'nugs' several days ahead of time. 

*Items needed: glass coffee pot, a metal screen or filter, paper coffee filters, clean glass bowl, splash guard, mason jar, plastic storage container, cutting utensils, and access to an electric oven.

Pros and Cons of Ethanol Extraction

Pros of Ethanol Extraction

  • Storage limits are much more lenient, with Ethanol allowing the facility to keep more storage in the facility while meeting fewer requirements allowing the user to extract large volumes of cannabis at once.
  • If done correctly, Ethanol extraction can eliminate the need for a dewaxing or winterization.
  • Great for creating full-spectrum hemp extracts and tinctures.

Cons of Ethanol Extraction

  • Ethanol is a polar solvent and will pull more water-soluble components from the plant, such as chlorophyll.
  • Ethanol has a much higher boiling point than Butane or Propane, making the recovery process generally slower and more difficult.
  • Ethanol is limited in the products it can produce. Making items like shatter or "sauce" is nearly impossible.
  • Post-processing for ethanol extraction is much more labor-intensive than hydrocarbon and involves several different methods of refinement and filtration.

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