Tag Archives: residual

October 7, 2021

Solvent Remediation – The Last Step for Safe, Clean Hemp Extraction

By Tom Bisbee

Botanical extraction is not specific to cannabis and hemp, and it is anything but new. Rudimentary forms of plant extraction have existed throughout history and evolved with high-tech equipment and scientific procedures for use in pharmaceuticals, dietary supplements and botanicals.

In food production, examples of hydrocarbon extraction processes are commonplace. Nut, olive and vegetable oil production use solvents to extract the oils. Decaffeinated coffee uses hydrocarbon extraction to remediate the caffeine, and making sugar from beets, or beer from hops, also requires solvents.

As such, the FDA has set guidelines for the amount of residual solvents considered safe for consumers to ingest. Yet, without FDA guidance in cannabis and hemp, many products aren’t being tested against these standards, and consumers will ultimately pay the price.

Understanding solvent remediation technology and processes

If we use ethanol extraction as an example, the extraction process is relatively simple. First, we soak the biomass in denatured or food-grade ethanol, ending up with a final solution that is 90-95% solvent. Then, we perform a bulk removal of the solvents, which takes out most, but not all, of the solvent. The next and final step should be to strip the remaining solvents from the extract entirely.

Stripping remaining solvents in bulk requires the right equipment.

But, in order to do so effectively, you need the right equipment, and unfortunately, this is where many producers fall short. Many producers use a vacuum oven to apply heat while reducing the headspace pressure to lower the solvent’s boiling point and evaporate it off.

However, it’s a static environment in a vacuum oven, which means the material is stagnant. So, the process may effectively remove the solvents close to the surface, but solvents deep inside the material tend to get trapped without some type of agitation or mixing.

The appropriate final step to complete solvent remediation is wipe-film distillation, which feeds small volumes into a column, which is then wiped into a very thin film and heated under vacuum pressure. Although the equipment necessary is costly, this last step removes any residual solvents from the product to create a safe, effective and consumable product.

Residual solvents present huge risks

As stated, many of the same solvents used in cannabis and hemp extraction have been considered safe in food production for decades. Reviewing chemical data sheets, many of the acceptable limits on solvents were determined for ingestion, which is fine for edibles and tinctures, but many cannabis and hemp products are intended for inhalation or vaporization.

Unfortunately, some solvents can have negative health impacts, especially for those using cannabis or hemp for medical purposes or with compromised immune systems. Plus, as a therapeutic and recreational substance, consumers may be consuming more than the recommended amount, as well as using the products several times a day. Unfortunately, long-term exposure or repeated inhalation of these residual solvents hasn’t been thoroughly researched.

For example, inhaling ethyl alcohol (ethanol) can irritate the nose, throat and lungs. Extended exposure can cause headaches, drowsiness, nausea, vomiting and unconsciousness. Repeated exposure can affect the liver and nervous system.

In the food industry, hexane is approved for extracting spices or hops, and this solvent is widely used in cannabis and hemp extraction. However, if used in an inhalable product, chronic exposure to hexane could be detrimental, with symptoms including numbness in the extremities, weakness, vision problems and fatigue.

Consumers deserve transparency

In the industry’s earliest days, companies were tight-lipped about their processes, the chemicals they used and how they removed them. Everyone thought they had the “secret sauce” and didn’t want to share their approach. Today, companies are more open about what they use, how they process it and providing that necessary transparency.

Lack of quality and consistent regulations in these industries creates confusion for the consumers and loopholes for producers. Some producers test for everything under the sun, and some producers know exactly which labs will pass their products, regardless of test results.

While the regulatory bodies are distracted by the amount of THC that might linger in products, getting sick is overshadowed by the risk of getting high. In the meantime, consumers are left to their own devices to determine which products are safe and which are not.

Although testing mandates and regulations will help clean up the industry, until then, consumers need to demand full-panel COAs that not only show cannabinoid potency but also accurately display the test results for residual solvents, pesticides and heavy metals.

March 8, 2021

Recent Developments in Supercritical CO₂ Winterization

By Aaron Green

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Supercritical carbon dioxide (CO₂) extraction is a processing technique whereby CO₂ is pressurized under carefully controlled temperatures to enable extraction of terpenes, cannabinoids and other plant molecules. Once the extract is obtained the crude is often subjected to an ethanol winterization process to remove chlorophyll, fats and waxes.

Green Mill Supercritical is a Pittsburgh-based manufacturing and engineering company focused on cannabis and hemp extraction. The company offers a range of CO ₂ extraction equipment where users can tune and control their extraction methods. They recently announced a technology advance enabling winterization in-process, which has the potential to remove the need for ethanol winterization.

We spoke with Jeff Diehl, director of marketing at Green Mill Supercritical, to learn more about the new process. Jeff was working in the tech industry in San Francisco in 2017 when he was invited to join Green Mill by his cousin, Jeremy Diehl, who is the founder and CTO.

Aaron Green: Before we get to your new technology, can you explain what industry trends you are watching?

Jeff Diehl: A big thing that I watch is the premium extract space. More and more consumers are demanding higher premium extracts. They want differentiated products. They want products that are safe and that have some kind of meaningful connection to the specific plant from which they came. Right now, CO₂plays a small role in the market for those products. Most premium products are generated through hydrocarbon extraction. So, I am watching how people are using CO₂to create the next generation of safe, premium products.

Aaron: What is the normal process for a CO₂ extraction today?

Jeff Diehl, director of marketing at Green Mill Supercritical

Jeff: The current CO₂ extraction process generally consists of two major phases to producing your final extract. In the first phase, you have extraction where you get your crude product. The second phase is post-extraction where you do cleanup to get your refined oil. Within that post-extraction phase, most operations include an ethanol-based winterization process.

Aaron: What does the winterization step do, exactly?

Jeff: Winterization is about removing waxes. Your main extraction is considered crude because it’s got a lot of materials from the plant that you don’t want. The large majority of unwanted material is waxes. Winterization is the process of using a solvent, traditionally ethanol, to separate the waxes from the cannabinoids. There are multiple challenges inherent in ethanol-based winterization that introduce cost, time and product loss. It’s terribly inefficient. Plus, there will always be residual ethanol left in your final product, and that’s not something consumers appreciate.

Aaron: You’ve recently announced a new process at Green Mill that moves the winterization step into the supercritical CO₂ equipment. Can you explain how that works?

Jeff: With our process, which we call Real-Time Winterization, there is no ethanol involved in winterization anymore. It is all done with CO₂ during the primary extraction. That’s the major advance of our process and although it has been attempted before, no one has succeeded at doing it in a viable way. You take a process which is normally four days – one day for CO2 extraction and three days for ethanol winterization – and you do it all in less than a day. We have automated software, sensors and pumps that makes this all possible.

Aaron: How does the quality of the resulting product compare with the new process?

Jeff: You can see the difference right away, if you’re at all familiar with extraction. It just looks clean and bright. Lab analysis has been very positive thus far, but we continue to run tests. Our R&D team has done multiple tests, mostly on hemp and CBD. That’s because we don’t have a license for THC. We’re currently engaging with a licensed partner so that we can collect more data on THC-containing products, so we can give exact numbers. But with CBD, we’ve done multiple tests to validate the method and the technology, and are seeing consistently excellent results in regards to both purity of the product and efficiency of the process.

Aaron: How do yields compare between the processes?

Jeff: From the data that we’ve seen in the industry, it looks like when you winterize with ethanol, you leave anywhere from 5 to 10% of your cannabinoids behind in the waxes. That’s just lost. With Real-Time Winterization using CO₂ we have seen recovery rates as high as 99%. We are continuing to investigate that result with testing to make sure it was not an outlier, but in any case, recovery rates look promising.

Aaron: One of the other issues with ethanol is taxes and the ability to find food grade supply. Do you have any perspective you can share on that?

Jeff: There are a number of advantages to moving away from ethanol. The sheer quantity of ethanol is a factor. There are a lot of regulations and fire requirements around managing large quantities of ethanol. The ethanol winterization process itself is not just one process. There are multiple stages, from mixing, to freezing, to filtering, to removing the solvent. These are all opportunities for things to go wrong, so you’re always managing those risks. Multiple large pieces of equipment, including fume hoods, filter skids, cryo freezers and rotary evaporators, are expensive and require heavy management.

I think Elon Musk said the best process is no process. Anytime in an industrial process when you can remove steps in the process, that’s the direction you want to go in. And, that’s what we’ve done. With this recent work, we have effectively removed post processing for certain categories of end product.

Aaron: Do you have any patents on the new process?

Jeff: We have a patent pending on both the method and the equipment, which is allowing us to talk about this as much as we are.

Aaron: So, how does this work if somebody already owns an existing piece of Green Mill equipment? Is this something that can be retrofitted? Is it a software upgrade?

Jeff: There are two components. One is an equipment upgrade, which can be done retroactively for existing customers, and one is a methodology upgrade, which we assist our customers with. The automation software inherently can handle the settings that you need to run the methodology. In fact, it’s that software and the rest of our existing tech stack, the proprietary pump, the triple inline fractionation, the precision and stability of the overall system, that is what made this winterization advance possible.

Aaron: Where are you rolling this out first? And do you plan to go international?

Jeff: International is definitely in the plan, since we’ve already sold systems abroad. We are currently getting ready to announce the opening of our beta program with the new technology. So, we’re not ready to sell this widely at this time, but we are taking submissions from companies that want to get in early and join us at the forefront of CO₂ extraction innovation.

Aaron: Okay, great. Thanks Jeff, that’s the end of the interview.

February 19, 2020

Cannabis Extracts for the Informed Consumer: Solvent or Solventless

By Nick J. Bucci

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Editor’s Note: Nick Bucci is a freelance cannabis writer. You can view his work here

As cannabis markets continue to gain traction, inconsistent and largely unpredictable markets have left recreational consumers in an informational fog. Try as the industry may, or may not to inform consumers, the lack of knowledge was evident when an established Colorado hash company opened a second operation in California. Expecting high demand for their solventless concentrates, the demand for their solvent-based counterparts came as a surprise. Initially hoping to eliminate solvent extracts from their product line-up, the company was forced to devote about half their overall production to solvent extracts, until information spreads and attitudes start to change. Over the past year several companies have joined the solventless side of history, but consumer understanding remains largely stagnant. For those immediately overwhelmed by terminology, cannabis extracts, concentrates or hash are all interchangeable terms describing concentrated cannabis. Under these umbrella terms, two distinct categories emerge depending upon whether chemical solvents were or were not used to extract the hash. Hence: solvent or solventless. A brief overview of cannabis concentrates will help consumers to understand the evolution away from solvent extractions and toward a superior solventless future.

ecxtractionfig2 — Science and economics merge when considering all the possible uses of concentrated compounds to final product formulations

Before regulated cannabis markets, cannabis extracts had long been in use. These old-world methods of cannabis extraction use very basic solventless techniques to create more potent, concentrated forms of cannabis. Dry sifting is easily the oldest form of cannabis extraction and a prime example of one solventless technique. Something as simple as shaking dried cannabis over metal screens and collecting the residue underneath creates a solventless product called keif. Dark brown bubble-hash, made popular decades ago, is another ancient technique using only ice and water to perform extractions without chemical solvents. After decades of stagnant and limited old-world methods, changes in legislation allowed cannabis sciences to flourish. These old-world hash methods were quickly forgotten, replaced by the astonishing progress of modern solvent extractions.

Tetrahydrocannabinol (THC), just one of hundreds of cannabinoids found in cannabis.

The emergence of solvent extracts revolutionized cannabis around 2011, creating new categories of cannabis products that exploded onto the scene. Not only did solvent extracts produce the most potent and cleanest forms of hash ever seen at this point, it also created new possibilities for hash-oil vape cartridges and cannabis extract infused edibles. These solvent extracts use butane, propane, or other hydrocarbon solvents to extract, or “blast” cannabinoids from the plant. By running solvents through cannabis and then purging or removing leftover, residual solvents, a super-potent, premium hash product is achieved. Regulated markets require testing to ensure only a safe level, if any, of the solvent used in the extraction process remains in the final product. This technology ushered in the first wave of concentrates to medical and recreational markets under the descriptive titles of wax, shatter and crumble. While these effective and affordable products can still be found today, far superior products have largely replaced wax and shatter. Distillation techniques can further purify and isolate THC-a, while removing harmful residual solvents. For a time, Solvent-free was used to describe this ultra-purified distillate, but the needless term has fallen out of use. Solvent-free is still a solvent extraction using chemical solvents, don’t be fooled. Distillation and CO2 extractions have fallen into general disfavor as they destroy the flavorful terpenes and valuable cannabinoids, that when present create an “entourage effect.” This “entourage effect” happens when the medicinal and recreational properties are most effective, pronounced, and impactful due to a full range of terpenes and cannabinoids being present in the final product. With companies manually reintroducing terpenes to their final extracts, it’s an attempt to restore what was lost during solvent extraction processes. Many brands claim to use cannabis derived or food-grade terpenes to infuse or reintroduce terpenes into their purified hash oils. While this adds flavor and taste, especially to distillate cartridges, it’s far from an ideal solution. Armed with this new information, the informed consumer looks for a full profile of terpenes and cannabinoids in their hash.

With terpene preservation a new priority, all aspects of hash making were reevaluated. By using fresh-frozen cannabis flower, solvent extractions quickly reached new heights. Using the same techniques as prior solvent extractions, the cannabis plant is frozen immediately upon harvesting, rather than trimming and drying the crop as usual. Freezing the plant preserves valuable terpenes helping to create a new category for hydrocarbon extracts under the general label of live resins. This live resin, containing vastly greater profiles of terpenes and cannabinoids than earlier waxes, shatters or crumbles is sold as live-resin sauce, sugar, badder, frosting, diamonds and more. Many versions of live resin re-use previous terms that describe consistencies. These live resin solvent extracts outperform the wax, crumble and shatters of old, and are priced accordingly. Some of the best solvent extracts available today use butane to extract hash oil, which forms THC-a crystals and diamonds seen in live resin sauces. Having learned the value of terpenes and cannabinoids, early efforts to purify THC were clearly misled. The industry defining use of fresh-frozen cannabis flowers greatly improved the quality of all extracts having realized the psychoactive effects are largely dependent on the various profiles of cannabinoids and terpenes. Pure THC-a crystals and isolates are easily achieved with solvent extractions but, produce inferior effects both medicinally and recreationally. Discovering the “entourage effect” as described earlier, these elements of cannabis allowed old-world solventless techniques to be re-inspired and reinvigorated with the benefit of healthy genetics and a hearty understanding of past mistakes.

Having gone full circle, solventless techniques are again at the forefront of the cannabis industry, having attained near perfection for our current understanding of cannabis anatomy.

figure1 extract — The increasingly finer mesh works to separate and extract microscopic trichomes

Using the lessons and tendencies of prior extractions, the solventless method, in all its final forms, begin with the same initial process to make ice-water hash oil. Often referred to as solventless hash oil (SHO), fresh-frozen flowers are submerged in ice and water, soaked and agitated before the water is filtered through mesh screens. As these mesh screens are measured by microns, the increasingly finer mesh works to separate and extract microscopic trichomes that break free from the cannabis plant. The 120- and 90-micron mesh screens usually collect pristine trichome heads. After scraping the remaining material from the screens, its sieved onto trays where the hash can dry using modern techniques of sublimation. The results are beyond phenomenal and are sure to shock even life-long cannabis consumers. This technique isolates only the most potent and psychoactive parts of the plant, to produce white to clear solventless ice water hash. When done with precision 6-star ice water hash is formed. The hash can be sold and consumed as is or undergo additional solventless techniques to produce hash-rosin. Not to be confused with live-resins, rosin uses pressure and slight heat to squeeze ice-water hash, into hash-rosin. Some companies have elected to whip their rosins into a solventless badder or allow their hash rosins to undergo a cold cure process that creates textures and varieties like hash rosin sauce. Regardless of the final solventless product, they all begin as ice water extractions. These simple, natural methods of extraction are quickly being adopted by companies known for live resin. As solventless extracts are safer, cleaner and superior in quality to solvent chemical extractions, the race is on as the industry shifts toward a solventless future.

While I’d be happy to never see another solvent extract again, without the miraculous breakthroughs and advances in all aspects of cannabis manufacturing and production we may have not yet arrived where we are today. When using solvents to extract, the trichomes, which contain the full spectrum of terpenes and cannabinoids, are dissolved by the solvent, which is then evaporated off, leaving behind dissolved trichomes. In solventless hash, these trichomes remain whole and are never dissolved or broken down. Instead they are broken free by agitation in ice and water, separating the trichome heads from their less-active stems. These valuable trichomes heads contain everything pertinent and are never destroyed, dissolved or melted like solvent-extractions are forced to do. The benefit of keeping the heads of these trichomes whole results in a far superior product expressing the full profile of terpenes and cannabinoids the way mother nature intended. This natural profile of trichomes lends itself directly to the entourage effect that solvent extracts were found to be missing.

Extraction techniques are not equal and depend upon whether quality or mass production is the aim. Solvent extracts have quickly begun to represent the old-guard of mass-produced cannabis concentrates, with the solventless new-guard focusing on quality, small batch, hash-rosin excellence.

December 30, 2019

How to Grow Cannabis Plants for Concentrate Production

By Andrew Myers

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While flower is still the most popular way to consume cannabis, the concentrates market is booming. Some predict concentrates will be nearly as popular as flower by 2022, with an estimated $8.5 billion in retail sales. That’s a lot of concentrates and, chances are, cannabis producers are already feeling the pressure to keep up.

Concentrates refer to products made from processing cannabis – often resulting in much higher THC or CBD percentages. The category includes oils, wax, dabs, shatter, live resin and hash. Consumers are increasingly drawn to these cannabis products for their near-immediate and intense effects. They’re often consumed through vaporization, dabbing or sublingual absorption and are sometimes favored by those who want to avoid smoking. Cannabis growers who have traditionally focused on flower yields may decide to prioritize quality and potency levels in order to tap into these changing consumer tastes.

What Growers Should Focus on to Produce High Quality Concentrates
We’ll let you in on a little secret: making good concentrates starts with good flower. If you’re starting with low-quality flower, it’s impossible to create a high-quality concentrate. Whatever qualities inherent to the flower you’re starting with will be amplified post-processing. So, really, the concentrate-making process starts at the seedling level, requiring the right care and attention to coax out the results you’re looking for.

But what makes good flower? While this can be a subjective question, those producing concentrates generally look for flowers with big, abundant trichomes. Trichomes are the small, dewy structures found across the cannabis plant on buds, leaves and even the stem. They’re responsible for producing the plant’s cannabinoids and terpenes – the chemical compounds that give a strain its unique benefits, aroma and taste. Evolutionarily, trichomes attract pollinators, deter hungry herbivores and provide some defense against wind, cold and UV radiation.

Generally, trichomes indicate how potent the flower is. Plus, what we’re most often looking for when making concentrates is higher cannabinoid and terpene profiles, while also ensuring absolute safety.

What measures can growers take to produce crops that are ideal for concentrate production? Start with the following:

Avoiding Contaminants
Just like you would wash your fruits and vegetables before consumption, consumers want to be sure there’s no dangerous residuals in the concentrate they are ingesting. Growers can avoid any post-process residuals by taking a few key steps, including:

Photo: Michelle Tribe, Flickr

Cutting out the pesticides. Any pesticides that are on your flowers before they go through processing will show up in your concentrates, often even more – you guessed it – concentrated. This is a serious health concern for consumers who might be sensitive to certain chemicals or have compromised immune systems. It’s dangerous to healthy consumers, too. Rather than spraying hazardous chemicals, growers could consider integrated pest management techniques, such as releasing predatory insects.
Limiting foliar spraying. Some growers will use foliar spraying to address nutrient deficiency or pest-related issues through delivering nutrients straight to the leaves. However, this can also result in contaminated concentrates. If you really need to spray, do it during the vegetative stage or investigate organic options.
Taking the time to flush the crop. This is a critical step in reducing potential contaminants in your concentrate, especially if you’re using a non-organic nutrient solution or fertilizer. Flushing simply means only giving your plants water during the final two weeks of flowering before harvest, resulting in a cleaner, non-contaminated flower and therefore a cleaner concentrate.

Perfecting the Indoor Environment
When cultivating cannabis indoors, growers are given ultimate control over their crop. They control how much light the plants receive, the lighting schedule, temperature and humidity levels. Creating the ideal environment for your cannabis crop is the number one way to ensure healthy plants and quality concentrates. There are many factors to consider when maintaining an indoor grow:

Temperature regulation. Trichomes are sensitive to temperature changes and start to degrade if they’re too hot or too cold. To maintain the best trichome structure, you’ll want to maintain an ideal temperature – for most strains, this falls between an idyllic 68 and 77 degrees.
Adequate light. For plants to perform photosynthesis indoors, they’ll need an appropriate light source – preferably one that is full-spectrum. Full-spectrum LEDs are able to closely replicate the sun and provide ample, uniform light to your crop. Another selling point for LEDs is their low heat output, making it much easier for growers to regulate ambient heat.
Rows of cannabis plants drying and curing following harvest
CO2. Another necessary ingredient for photosynthesis is CO2. Providing your indoor crops with CO2 can boost plant size and yields and, therefore, provides more surface area for trichomes to develop and thrive.
Cold snap prior to harvest. Some growers rely on this age-old tactic for one last push before harvest – lowering their temperature for a few days right at the end of the flower cycle. They believe this puts the plants into a defense mode and will produce more trichomes in order to protect themselves.

Following Best Practices Post-Harvest
You made it to harvest – you’re almost done!

When harvesting and storing your plants, handle them with care to reduce damage to trichomes. If you’re planning on immediately making concentrates, you can move forward to the drying and curing process. If you’re going to wait a few weeks before processing, freeze your plants. This will preserve the cannabinoid and terpene profiles at their peak.

As the cannabis industry continues to expand, more consumers are likely to reach for concentrates at their local dispensaries. It makes sense that businesses want to diversify their offerings to satisfy customers looking for the most effective way to consume cannabis. As with any cannabis-derived product, producers will want to prioritize quality and safety – especially in the concentrate market.

January 23, 2017

Green Man Cannabis Recalls Due to Pesticide Residue Detection

By Aaron G. Biros

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Denver-based Green Man Cannabis last week voluntarily recalled batches of cannabis sold to both medical patients and recreational consumers. The recall comes after the discovery of off-label pesticides during inspections in both dry-flower cannabis and infused products.

According to the Denver Department of Environmental Health (DEH), the products have labels that list an OPC License number of 403-00738, 403-00361, or 403R-00201. The cannabis in question is not a specific batch, rather, “All plant material and derived products originating from these cultivation facilities are subject to the recall.” The DEH’s statement includes contact information for the company (email: recall@greenmancannabis.com) and the DEH Public Health Inspections Division (email: phicomments@denvergov.org or 720-913-1311).

The DEH statement does not mention which pesticides were detected or the levels at which they were detected. Christian Hagaseth, founder of Green Man Cannabis, says the chemical detected was Myclobutanil. “We had used Eagle 20 in the past, [the pesticide that contains Myclobutanil] but we stopped using it as soon as it was banned,” says Hagaseth. “The DEH found the residues in the growing environment so we immediately performed a voluntary recall.” Green Man has three cultivation facilities, one of which they suspect is contaminated from pesticides sprayed a few years ago.

Christian Hageseth, founder of Green Man Cannabis

As far as corrective actions being taken, Hagaseth says they are doing a thorough cleaning and sanitation in two of their grows and a complete remediation plan in the suspected contaminated grow. “This was a good learning experience- the key takeaway for us is we need to clean these environments more consistently,” says Hagaseth. “I am grateful that the system is working; public health and environmental safety are being looked after here.” Hagaseth says the facility in question was operating almost without interruption since 2009, but they adjusted and learned to implement preventative actions following the recall.

The DEH says there have been zero reports of illness related to the recall. “The possible health impact of consuming marijuana products with unapproved pesticide residues is unknown,” the statement reads. “Short and long-term health impacts may exist depending on the specific product, duration, frequency, level of exposure and route of exposure.” The DEH advises consumers that may be concerned to reach out to their physician.

The DEH performs routine inspections of cannabis infused product manufacturers and retail locations in Denver, as well as investigating complaints. “I am sorry that it happened to us, but I am happy the system is working and we are more than happy to comply,” says Hagaseth.