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5 Questions Every Cannabis Extractor Should Be Able to Answer

By Jeremiah Seims and Samuel Shomper, sales manager and senior mechanical engineer at Prospiant
Published: Nov 01, 2021   

Image credit: Prospiant

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Planning to construct or expand and operate a cannabis or hemp extraction facility? Start by asking these five critical questions about your biomass and solvents. Your answers could shape how you optimize or restrict your yields, efficiency, and profitability.

In this article, we cover the key questions and considerations for extraction operators, regardless of whether you are just starting up a business or expanding multi-state locations.

1. Do you really know how potent your biomass is?

Biomass potency varies widely across farms and cultivars, so testing before extraction to determine levels of THC and CBD is essential.

Most extraction facilities do not have in-house testing labs; many smaller operators collect biomass samples and send them to outside labs for analysis. However, results can vary between labs due to inconsistent testing protocols. To achieve more predictable results, consider investing in small-scale testing systems that utilize UV light to determine THC and CBD levels within biomass. Their accuracy approximates full lab testing but by conducting the analysis in-house, you can better control the testing procedures and achieve consistently reliable results.

Another factor that greatly influences potency is how much cannabis flower is included in your biomass.

In the cannabis and hemp industry, biomass typically refers to the plant material left over for processing after the highly prized flower (colas or buds) of the plant has been removed. Flower contains the highest THC levels, so the majority of flower harvested in the United States goes into smokable products. As much as 40 percent of flower in some states, however, is added to biomass for extraction of cannabinoids, which will be used to manufacture edibles, infused and vaping products, as well as extractions for dabbing, distillates, and live resin. 

When purchasing biomass, assessing its cost on a dollar-per-gram of cannabinoid basis is perhaps the most accurate method of assessing the cost of your inputs. You need accurate potency test results to get there.

2. How fine or course should you mill your biomass?

How finely you mill or shred cannabis or hemp biomass plays a large role in determining how much biomass can fit into the extraction chamber. The finer you mill your biomass, the more surface area is available and the quicker the solvent will dissolve the cannabinoids, which include:

Terpenes — the compounds that give cannabis and hemp products their distinctive aromas and contribute to their varied flavors. Different combinations of terpenes are widely considered to be a driving factor in the type of high that consumers experience.

Crude oil — the dark, highly viscous substance similar in texture to thick molasses. Although it is rich in the major (CBD and THC) and minor cannabinoids (CBN and CBG), it still contains undesirable components such as plant particulates, solids, and waxes. Removing these components requires that crude oil be further refined. Crude oil is one of the major building blocks of the cannabis industry because most end-products start off as crude before being further refined and purified.

Resin — the valuable oily compounds contained in trichomes, including terpenes, flavonoids and high concentrations of cannabinoids such as THC. Resin can also contain undesirable elements like waxes and chlorophyll. Resin is typically further processed into dabbable concentrates.

Image credit: Prospiant.

To maximize extraction process efficiency, I recommend milling biomass to between a quarter inch or an eighth inch. You do not want to grind biomass that is too large or coarse because the solvent will not fully penetrate it to achieve a complete extraction. At the same time, you want to avoid a grind feed that is too fine because more of the biomass will end up in your tincture. Additional filtration steps will then be required.

Another important consideration related to mill size: there are also compounds within the biomass that operators should avoid extracting. They are usually found within the cells of the plant, but if these walls are shredded, the compounds can break through and release undesirable compounds into the solvent. This also leads to extra filtration and processing time.

One other impact of mill size is on productivity of your extraction process. More fine-milled biomass can be uniformly packed into the filter bags used in ethanol centrifuge extraction processes or loaded directly into CO2 extraction vessels compared to coarse-milled biomass. So mill size directly influences how many pounds of biomass can be processed during each extraction.

3. How much time should you spend on extraction?

My best answer to this frequently asked question is: it depends on which extraction process you select.

Cannabis and hemp require different extraction efficiencies. Cannabinoid yield from cannabis is generally much higher than that of hemp because hemp contains less oleoresin. This means that you need much more biomass or plant material to glean out similar amounts of oil. Once you have chosen to process cannabis or hemp, your next decision is about which extraction process to utilize.

Ethanol extraction is high throughput and perfect for making distillate and isolates at scale. However, ethanol binds to terpenes, rendering them unusable. Many operators later add terpenes to their ethanol distillate if needed for their end-products. And there is this important safety note: ethanol processing requires a C1D2 control area.

CO2 extraction has a lower throughput than ethanol but utilizes an inert gas for processing instead of a liquid solvent or explosive gas. CO2 enables the capture of terpenes prior to extraction for later use. However, CO2 raw extract requires additional processing to remove lipids, fats, and waxes. CO2 systems operate at high pressures and varying temperatures, but without volatile compounds so no control zone is required for safety.

Butane or propane extraction (BHO/hydrocarbon) is a lower-throughput process like CO2 but captures all major terpenes and cannabinoids. It is best for concentrates such as dabs, sauce, shatter, and diamonds, which are gaining popularity with consumers. A C1D1 control zone for explosive gases is required.

Large-scale operators can process as much as 1,000 pounds of biomass a day. Small-scale operations might process no more than 1,000 pounds a month. The time needed to complete an entire extraction cycle is going to directly determine how many extractions can be performed in any given shift. So the throughput you want to achieve will determine what type of extraction equipment and how many units are needed. To meet each operator’s unique needs, equipment manufacturers offer extraction systems in a range of sizes. At Prospiant, we have equipment that is designed to extract from 10, 25, 80, or 100 pounds of biomass during an 8-hour shift.

In addition to the extraction equipment, other important factors that influence extraction time include:

  • The mill size, which determines how much biomass fits into the extraction vessel and can be extracted per cycle.
  • Downtime for maintenance and cleaning.
  • Advanced extraction techniques involving chilling the solvent and pre-freezing the biomass.

Each should be considered and understood by operators in order to precisely calculate extraction throughput and overall yields. 

4. What is the right temperature for your solvent?

Temperature of the solvent, along with the mill size of the biomass, will determine the amount of time required for efficient extraction of the primary derivatives. Generally, the colder the temperature, the slower the solvent will dissolve cannabinoids from the biomass.

Ethanol extraction can be performed under room or cold temperatures, depending on your desired end-product. However, typically large-scale ethanol extraction is performed most efficiently by pre-chilling the ethanol solvent down to as low as -40 °C (-40 °F) to reduce post-extraction processes. The cooling of the ethanol is typically performed in an inline chiller.

This first step of the cold ethanol extraction process is performed to increase the efficiency of the solvent’s ability to separate cannabinoids and other desirable compounds from the biomass, thereby reducing the number of post-extraction processes.

Of course, warm or room-temperature ethanol extraction can also be performed but it requires additional steps to ensure a high-quality end-product. It is for this reason that cold temperature ethanol extraction is more commonly used in large-scale ethanol extraction labs.

In CO2 extraction, 30.77 °C (87.4 °F) is the critical line. Below it, extraction requires subcritical processes. Extraction above it requires supercritical processes which run faster and yield more potent products. Slower subcritical runs, however, are gentler to the plant material and do not remove fats and waxes. This minimizes or eliminates the need for additional processing. And many operators will do their terpene runs right around the critical line; the process does not pull any of the other oils.

In ethanol extraction, we recommend chilling your process ethanol to -40 °C (-40 °F) prior to extraction and freezing your biomass if possible, to efficiently capture cannabinoids while minimizing the extraction of fats, lipids, waxes, sugars, and chlorophyll. Ethanol is a polar solvent and dissolves gums, sugars, fats and other undesirable molecules but not the target oils. Additional filtration and processing are then needed to remove the undesirables. Lowering the ethanol temperature to between -35 °C (-31 °F) and - 55 °C (-67 °F) will convert it to a non-polar solvent that only dissolves the cannabinoids.

Cold extraction actually streamlines your process. Should you decide to extract at room temperature or higher, you will need to invest in more post-processing equipment and standard processes for color remediation and winterization to remove fats, waxes, and lipids from a plant. Winterization is needed when oil has been extracted at a very high temperature or pressure and prevents the end-products from being cloudy and dark.

5. How much ethanol do you lose during each extraction?

During extraction, the cannabis or hemp biomass is soaked in a solvent and agitated in a mechanical centrifuge. Most of the solvent is recovered. But depending on the process and equipment involved, a small amount of the solvent remains in the biomass or is lost when the extraction vessel or other valves and connections are opened.

In CO2 extraction, that is not a problem. CO2 extraction yields clean and pure cannabinoid derivatives. It is considered to be safe because CO2  is non-volatile and leaves no residual chemicals.

During ethanol extraction, it is inevitable that you will lose ethanol due to evaporation and because some of the solvent remains in the biomass. State and local governments regulate the disposal of the biomass after extraction, so operators will have to plan to take extra steps to ensure safe disposal. In some jurisdictions, for example, the biomass must be stored on-site and dried before it is removed and transported to a landfill. And in other jurisdictions, operators are required to replace the ethanol after each batch or lot of biomass. 

Be sure to evaluate how well the extraction equipment you are considering can recover ethanol for re-use in the next batch. Closed-loop centrifuges and extraction systems from Prospiant remove at least 98 percent of the ethanol from the biomass. This ensures that you are consistently capturing the maximum amount of cannabinoids per extraction and optimizing your lab’s yield. 

Partner with end-to-end extraction experts

Asking and answering these five key questions is only the start of your journey to better understanding the variables that play a role in accurately calculating your cannabis and hemp extraction yields.

Whether you want to build, operate, or invest in a new extraction business, or intend to expand or diversify your established cannabinoid processing operation, partner with experts with a proven record of developing complete extraction solutions. Work directly with specialists who can help you stay ahead of new processes and the latest equipment. Your ideal partner also will share unique insights to help you better understand business, marketplace, and regulatory trends. That is the recipe for getting your cannabis and hemp products to recreational and medicinal markets on time, within budget. It is how you will prepare to achieve your extraction business goals.


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