Ethanol Extraction 101
Many companies within a maturing extraction industry have released numerous new technologies that promise they are the “next best thing.” The thing you probably will not find along with the tall tales of huge throughput is the science, and why each of the methods have their benefits and limitations. We will be taking a closer look in this article at the hyrdroarbon extraction vs. cannabis ethanol extraction process for mid-scale operations (200 to 1000 pounds of processing input material a day, in traditional cannabis or hemp).
Let’s begin with the science behind cannabis extraction. A solvent (hydrocarbon or ethanol) is passed over plant material to dissolve the plant’s active compounds, in this case the terpenes and cannabinoids, but not every solvent is created equal. Since ethanol is referred to as a “polar” solvent, it is going to be more hydrotropic, which means it wants to bind with the plant’s water soluble components. This results in a less potent and less pure end product generally that requires more post processing (with the general exception to that is when producing full spectrum hemp extracts, since it has been proven some of the hemp plant’s water soluble components have genuine health benefits). The solvent in hydrocarbons is non-polar which means it binds to more of the plant’s (terpenes and cannabinoids only) fat soluble components. This results in a higher purity extract on the ending of the primary extraction process.
Proponents of ethanol extraction argue that a majority of plant component water soluble extraction may be circumvented by maintaining very cold temperatures under -5F, and to an extent that is true, but there is also a problem.
In developing hemp and cannabis markets, the hottest products and crazes now revolve around isolates/crystals and “The Sauce” (HTFSE). An isolate is basically a crystalline structure of one molecle, usually CBD or THC-a cannabinoids, with certain products such as “The Sauce” adding in a terpene layer as well into the mix.
Advantages of Ethanol Extraction
There are much more lenient storage limits with Ethanol which allows the facility to have more storage kept inside the facility while fewer requirements being met that allows larger cannabis volumes to be extracted by the user at one time.
When done correctly, Ethanol extraction may eliminate the need for winterization or a dewax.
Excellent for making full spectrum hemp tinctures and extracts.
To make these products, generally you need to have an initial extract purity that is higher than 80%, especially in cases of CBD crystalline, and also in cases of THC-A crystalline scenarios. Due to ethanol’s polar nature as a solvent for purposes of primary extraction hardly ever reaches these concentrations of purity so has limitations in making them a less pure form of full spectrum hemp extract (that has its own bustling market).
Ethanol Cannabis Extract
Proponents of ethanol will say their primary extract can be crystallized through downstream processing or further purification, and that is true. What they will not tell you is the purification process is difficult to scale, costly, and labor intensive to make crystalline. Normally the process involves multiple stages of chromatography, separation, and filtration,in addition to solvents like dichloromethane, chloroform, and dimethalether. However,on a big scale, like downstream processing, it makes a lot of sense since it is hard use, permit, or store huge amounts of hydrocarbon in a continuous feed style of plant operations. Massive efficiencies are also gained in the ethanol post processing process when done on a large scale.
In the industry there is a longstanding joke regarding the “Loss Ness Monster” – which is the ethanol extractor which has both unparalleled purity and incredible throughput. The problem with it is nobody has seen it ever. Ethanol is a viable extraction method and, like other methods, has its own advantages and disadvantages.
Disadvantages of Ethanol Extraction
Ethanol is a type of polar solvent and pulls higher amounts of water soluble components like chlorophyll from the plant.
Ethanol has a boiling point that is much higher than Propane or Butane which makes the recovery process usually more difficult and slower.
There are a limited number of products that ethanol can produce making it nearly impossible to make items like “sauce” and shatter.
Ethanol extraction post processing is a lot more labor intensive compared to hydrocarbon and involves using several different filtration and refinement methods.