CLAIMS OF TIME & RECOVERY
Extraction as an industry is growing fast, and there are a number of companies vying for market share and consumer attention. In the CO2 space alone, there are dozens of companies supplying equipment to the industry. In this space, it's natural to see organizations trying a number of different tactics to get ahead.
Unfortunately, in the course of competitive business, statements can be made that are inaccurate and/or false. One typical myth that has had its time in the spotlight is the subject of yields. This topic can arise when people try to make simple comparisons between different types of equipment, and it is used as a measure of efficiency. However, as has been covered numerous times (check out this article), the subject of yields can be confusing and even misleading.
There have been numerous instances where the question "what is the yield on this machine?" is followed up with a simple numerical response like, "30%". Without even questioning the starting material going into the system, this can be misleading. If one were to use starting material that is 5% cannabinoids into a system, getting 30% yield would mean that most of the output would be non-cannabinoid material.
While the topic of yields and the confusion surrounding it has been discussed for years, a new subject of interest has come to light - percent extraction efficiency, also referred to as recovery percentage . The percent extraction efficiency is a number calculated by measuring the difference in cannabinoid mass between the feedstock and the post-extraction raffinate. As a simplistic example, if 100g of a specific compound existed in a specific volume of plant material, and the extraction output was measured to have 97g, the percent extraction efficiency would be 97%.
Unfortunately, while this topic has started to gain traction, so too have some of the myths surrounding the process. For example, some are reporting that they're hearing statements about the recovery percentage of a particular system within a specific period of time. For arguments sake, let's use the example of a 95% recovery in a run-time of 2 hours. These results are fantastic, but are they even possible? Keep reading to find out.
THE SCIENCE OF EXTRACTION
CO2 extraction is a process that has as part of its foundation a few key scientific principles. The key factors in an extraction are temperature, pressure, time, and flowrate. Under a set of parameters (temperature and pressure) during a run of a specific duration (time) and based on the overall volume of solvent passing through the substrate (flowrate), an extraction will produce a quantity of crude oil.
For different compounds within the biomass, different temperature and pressure settings can increase or decrease their solubility within the solvent. As well, the more time the extraction is given to run, the more of that particular compound can be extracted (this article talks about the "declining curve" of recovery that is typically noticed). Finally, the amount of solvent that is flowing through the chamber can also increase the overall efficiency of the extraction.
None of these factors are magical. Rather, they are scientific principles upon which extraction is based. The end result of the extraction is similarly based on the science. Given a specific set of parameters, the laws of physics, the phenomenon of mass transfer and solubility, an extraction occurs.
THE EXTRACTION CURVE
This image represents the extraction curve, or better put, gives a graphical look at the amount of cannabinoids that can be pulled from the plant material over time. The familiar "declining curve" shows that in the first part of the extraction, the majority of cannabinoids are recovered. As the solvent continues to penetrate the biomass, components that are further from the surface of the material take longer to recover. Over the course of the run, the remaining desirables are pulled.
Given the laws of physics and the physical properties of solvent and biomass, this shows what happens when appropriate temperature and pressure parameters are set when targeting cannabinoids. These parameters are chosen as they are the most favorable for extraction of target compounds with as little co-extraction of non-desirable components like fats and waxes.
Technically, 95% recovery in 2 hours is possible. This can be accomplished by drastically increasing temperature and pressure settings during the extraction. Unfortunately, the by-product of such a process is the complete extraction of both desirable and undesirable compounds. This leads to a situation where post-processing requires greater amounts of time, energy, equipment and resources. In this case, maintaining these numbers indefinitely is neither profitable nor sustainable.
When evaluating claims that are made across the industry, it is wise to get the actual details behind the statement. If a claim like our example is heard, then the discussion should focus on the how - how is it possible to reach those numbers, and what are the downsides that also result? Similarly, hearing wild claims about the yield of a particular extraction system should be met with queries regarding the biomass. What are the percentages of desirable compounds in that plant material, and how does that compare to the claim (remember, 30% yield from a 20% feedstock is nothing short of magical)?
As the industry gains momentum, we can anticipate more outrageous and fantastic claims. As in most situations, regardless of industry or transaction, critical thinking pays off. Like the saying goes, “if it sounds too good to be true, it probably is.” While some “claims” can technically be true, the realities may not be close to the desired outcome. Educate yourself, purchase wisely.
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