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Clear vs. Pure: How Fallacies and Ignorance of Extraction Misrepresent the Cannabis Flower

By Dr. Markus Roggen
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Demand for cannabis extracts, in particular vaping products, is at an all-time high. People want good oil, and they want to know something about the quality of it. It is therefore time to take a step back and consider the process from plant to cartridge. What is the current industry standard for cannabis extraction, what constitutes quality and where might we need to make some adjustments?

Right now, “clear” oil is hot. Customers have been led to believe that a pale gold extract is synonymous with the best possible cannabis concentrate, which is not necessarily the case. Producing a 95% pure THC extract with a translucent appearance is neither a great scientific feat nor a good representation of the whole cannabis flower. Moreover, it runs counter to the current trend of all-natural, non-processed foods and wellness products.

“My carrots are organic and fresh from the farmers market, my drink has no artificial sweeteners and my honey is raw, but my cannabis oil has undergone a dozen steps to look clear and still contains butane.”Cannabis is a fascinating plant. It is the basis of our livelihood, but more importantly, it enhances the quality of life for patients. The cannabis plant offers a plethora of medicinally interesting compounds. THC, CBD and terpenes are the most popular, but there are so many more. As of the most recent count, there are 146 known cannabinoids1. Cannabinoids are a group of structurally similar molecules2, including THC and CBD, many of which have shown biological activity3.

Then there are terpenes. These are the smaller molecules that give cannabis its distinct smell and flavor, over 200 of which have been identified in cannabis4. But wait, there’s more. The cannabis plant also produces countless other metabolites: flavonoids, alkaloids, phenols and amides5. All these components mixed together give the often-cited entourage effect6,7.

Current industry standards for cannabis oil extraction and purification stand in marked contrast to the complexity of the plant’s components. Due to an unsophisticated understanding of the extraction process and its underlying chemistry, cannabis oil manufacturers frequently produce oil of low quality with high levels of contamination. This necessitates further purifications and clean up steps that remove such contaminants unfortunately along with beneficial minor plant compounds. If one purifies an extract to a clear THC oil, one cannot also offer the full spectrum of cannabinoids, terpenes and other components. Additionally, claiming purities around 95% THC and being proud of it, makes any self-respecting organic chemist cringe8.

Precise control of extraction conditions leads to variable, customized concentrates. THC-A crumble, terpene-rich vape oil, THC sap (from left to right).

The labor-intensive, multi-step extraction process is also contrary to “the clean-label food trend”, which “has gone fully mainstream”9. Exposing the cannabis flower and oil to at least half a dozen processing steps violates consumer’s desire for clean medicine. Furthermore, the current practice of calling supercritical-CO2-extracted oils solvent-less violates basic scientific principles. Firstly, CO2 is used as a solvent, and secondly, if ethanol is used to winterize10, this would introduce another solvent to the cannabis oil.

We should reconsider our current extraction practices. We can offer cannabis extracts that are free of harmful solvents and pesticides, give a better, if not full, representation of the cannabis plant and meet the patients’ desire for clean medicine. Realizing extracts as the growth-driver they are11 will make us use better, fresher starting materials12. Understanding the underlying science and learning about the extraction processes will allow us to fine-tune the process to the point that we target extract customized cannabis concentrates13. Those, in turn, will not require additional multi-step purification processes, that destroys the basis of the entourage effect.

The cannabis industry needs to invest and educate. Better extracts are the result of knowledgeable, skilled people using precise instruments. Backroom extraction with a PVC pipe and a lighter should be horror stories of the past. And only when the patient knows how their medicine is made can they make educated choices. Through knowledge, patients will understand why quality has its price.

In short, over-processing to make clear oil violates both the plant’s complexity and consumers’ desires. Let us strive for pure extracts, not clear. Our patients deserve it.


[1] Prof. Meiri; lecture at MedCann 2017

[2] ElSohly, Slade, Life Sciences 2005, 539

[3] Whiting, et. al., JAMA. 2015, 2456

[4] Andre, Hausman, Guerriero, Frontiers in Plant Science 2016, 19

[5] Hazekamp, et. al., Chemistry of Cannabis Chapter 3.24; 2010 Elsevier Ltd.

[6] Ben-Shabat, et al.; Eur J Pharmacol. 1998, 23

[7] Mechoulam, et al.; Nat Prod Rep. 1999, 131

[8] Medical and Research Grade chemicals are generally of purities exceeding 99.9%

[9] Bomgardner, Chemical & Engineering News 2017, 20

[10] Winterization is the industry term for what is correctly referred to as precipitation.

[11] Year-over changes to market shares in Colorado 2015 to 2016: Concentrates 15% to 23%; Flower 65% to 57%, BDS Analytics, Marijuana Market Executive Report, 2017

[12] Further reading about the whole extraction process: B. Grauerholz, M. Roggen; Terpene and Testing Magazine, July/Aug. 2017

[13] Further reading about optimizing CO2 extraction: M. Roggen; Terpene and Testing Magazine, May/June 2017, 35

Implementing a HACCP Plan in Cannabis Processing

By Aaron G. Biros
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Hazard analysis and critical control points (HACCP) is a robust management system that identifies and addresses any risk to safety throughout production. Originally designed for food safety through the entire supply chain, the risk assessment scheme can ensure extra steps are taken to prevent contamination.

The FDA as well as the Food Safety and Inspection Service currently require HACCP plans in a variety of food markets, including high-risk foods like poultry that are particularly susceptible to pathogenic contamination. As California and other states develop and implement regulations with rigorous safety requirements, cannabis cultivators, extractors and infused product manufacturers can look to HACCP for guidance on bolstering their quality controls. Wikipedia actually has a very helpful summary of the terms referenced and discussed here.

Dr. Markus Roggen, vice president of extraction

The HACCP system consists of six steps, the first of which being a hazard analysis. For Dr. Markus Roggen, vice president of extraction at Outco, a medical cannabis producer in Southern California, one of their hazard analyses takes place at the drying and curing stage. “When we get our flower from harvest, we have to think about the drying and curing process, where mold and bacteria can spoil our harvest,” says Dr. Roggen. “That is the hazard we have to deal with.” So for Dr. Roggen and his team, the hazard they identified is the potential for mold and bacteria growth during the drying and curing process.

The next step in the HACCP system is to identify a critical control point. “Correct drying of the flower will prevent any contamination from mold or bacteria, which is a control point identified,” says Dr. Roggen. “We also have to prevent contamination from the staff; it has to be the correct environment for the process.” That might include things like wearing gloves, protective clothing and hand washing. Once a control point is identified, the third step in the process is to develop a critical limit for those control points.

A critical limit for any given control point could be a maximum or minimum threshold before contamination is possible, reducing the hazard’s risk. “When we establish the critical limit, we know that water activity below 0.65 will prevent any mold growth so that is our critical limit, we have to reach that number,” says Dr. Roggen. The fourth step is monitoring critical control points. For food manufacturers and processors, they are required to identify how they monitor those control points in a written HACCP plan. For Dr. Roggen’s team, this means using a water activity meter. “If we establish the critical control point monitoring, water activity is taken throughout the drying process, as well as before and after the cure,” says Dr. Roggen. “As long as we get to that number quickly and stay below that number, we can control that point and prevent mold and bacteria growth.”

One of the cultivation facilities at Outco

When monitoring is established and if the critical limit is ever exceeded, there needs to be a corrective action, which is the fifth step in a HACCP plan. In Dr. Roggen’s case, that would mean they need a corrective action ready for when water activity goes above 0.65. “If we don’t have the right water activity, we just continue drying, so this example is pretty simple,” says Dr. Roggen. “Normal harvest is 7 days drying, if it is not dry enough, we take longer to prevent mold or bacteria growth.”

The sixth step is establishing procedures to ensure the whole system works. In food safety, this often means requiring process validation. “We have to double check that our procedure and protocols work,” says Dr. Roggen. “Checking for water activity is only a passive way of testing it, so we send our material to an outside testing lab to check for mold or bacteria so that if our protocols don’t work, we can catch those problems in the data and correct them.” They introduced weekly meetings where the extraction and cultivation teams get together to discuss the processes. Dr. Roggen says those meetings have been one of the most effective tools in the entire system.

Dr. Roggen’s team identified worker safety as a potential hazard

The final step in the process is to keep records. This can be as simple as keeping a written HACCP plan on hand, but should include keeping data logs and documenting procedures throughout production. For Dr. Roggen’s team, they log drying times, product weight and lab tests for every batch. Using all of those steps, Dr. Roggen and his team might continue to update their HACCP plans when they encounter a newly identified hazard. While this example is simplistic, the conceptual framework of a HACCP plan can help detect and solve much more complex problems. For another example, Dr. Roggen takes us into his extraction process.

Dr. Roggen’s team, on the extraction side of the business, uses a HACCP plan not just for preventing contamination, but for protecting worker safety as well. “We are always thinking about making the best product, but I have to look out for my team,” says Dr. Roggen. “The health risk to staff in extraction processes is absolutely a hazard.” They use carbon dioxide to extract oil, which carries a good deal of risks as well. “So when we look at our critical control points we need to regularly maintain and clean the extractor and we schedule for that,” says Dr. Roggen.

Gloves, protective clothing, eyewear and respirators are required for workers in the extraction process.

“My team needs respirators, protective clothing, eyewear and gloves to prevent contamination of material, but also to protect the worker from solvents, machine oil and CO2 in the room.” That health risk means they try and stay under legal limits set by the government, which is a critical limit of 3,000 ppm of carbon dioxide in the environment. “We monitor the CO2 levels with our instruments and that is particularly important whenever the extractor is opened.” Other than when it is being opened, Dr. Roggen, notes, the extractor stays locked, which is an important worker safety protocol.

The obvious corrective action for them is to have workers leave the room whenever carbon dioxide levels exceed that critical limit. “We just wait until the levels are back to normal and then continue operation,” says Dr. Roggen. “We updated our ventilation system, but if it still happens they leave the room.” They utilize a sort of double check here- the buddy system. “I took these rules from the chemistry lab; we always have two operators working on the machine on the same time, never anyone working alone.” That buddy check also requires they check each other for protective gear. “Just like in rock climbing or mountain biking, it is important to make sure your partner is safe.” He says they don’t keep records for employees wearing protective gear, but they do have an incident report system. “If any sort of incident takes place, we look at what happened, how could we have prevented it and what we could change,” says Dr. Roggen.

He says they have been utilizing some of these principles for a while; it just wasn’t until recently that they started thinking in terms of the HACCP conceptual framework. While some of those steps in the process seem obvious, and it is very likely that many cannabis processors already utilize them in their standard operating procedures and quality controls, utilizing the HACCP scheme can help provide structure and additional safeguards in production.

Understanding Dissolved Oxygen in Cannabis Cultivation

By Aaron G. Biros
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Oxygen plays an integral role in plant photosynthesis, respiration and transpiration. Photosynthesis requires water from the roots making its way up the plant via capillary action, which is where oxygen’s job comes in. For both water and nutrient uptake, oxygen levels at the root tips and hairs is a controlling input. A plant converts sugar from photosynthesis to ATP in the respiration process, where oxygen is delivered from the root system to the leaf and plays a direct role in the process.

Charlie Hayes has a degree in biochemistry and spent the past 17 years researching and designing water treatment processes to improve plant health. Hayes is a biochemist and owner of Advanced Treatment Technologies, a water treatment solutions provider. In a presentation at the CannaGrow conference, Hayes discussed the various benefits of dissolved oxygen throughout the cultivation process. We sat down with Hayes to learn about the science behind improving cannabis plant production via dissolved oxygen.

In transpiration, water evaporates from a plant’s leaves via the stomata and creates a ‘transpirational pull,’ drawing water, oxygen and nutrients from the soil or other growing medium. That process helps cool the plant down, changes osmotic pressure in cells and enables a flow of water and nutrients up from the root system, according to Hayes.

Charlie Hayes, biochemist and owner of Advanced Treatment Technologies

Roots in an oxygen-rich environment can absorb nutrients more effectively. “The metabolic energy required for nutrient uptake come from root respiration using oxygen,” says Hayes. “Using high levels of oxygen can ensure more root mass, more fine root hairs and healthy root tips.” A majority of water in the plant is taken up by the fine root hairs and requires a lot of energy, and thus oxygen, to produce new cells.

So what happens if you don’t have enough oxygen in your root system? Hayes says that can reduce water and nutrient uptake, reduce root and overall plant growth, induce wilting (even outside of heat stress) in heat stress and reduce the overall photosynthesis and glucose transfer capabilities of the plant. Lower levels of dissolved oxygen also significantly reduce transpiration in the plant. Another effect that oxygen-deprived root systems can have is the production of ethylene, which can cause cells to collapse and make them more susceptible to disease. He says if you are having issues with unhealthy root systems, increasing the oxygen levels around the root system can improve root health. “Oxygen starved root tips can lead to a calcium shortage in the shoot,” says Hayes. “That calcium shortage is a common issue with a lack of oxygen, but in an oxygen-deprived environment, anaerobic organisms can attack the root system, which could present bigger problems.”

So how much dissolved oxygen do you need in the root system and how do you achieve that desired level? Hayes says the first step is getting a dissolved oxygen meter and probe to measure your baseline. The typical dissolved oxygen probe can detect from 20 up to 50 ppm and up to 500% saturation. That is a critical first step and tool in understanding dissolved oxygen in the root system. Another important tool to have is an oxidation-reduction potential meter (ORP meter), which indicates the level of residual oxidizer left in the water.

Their treatment system includes check valves that are OSHA and fire code-compliant.

Citing research and experience from his previous work, he says that health and production improvements in cannabis plateau at the 40-45 parts-per-million (ppm) of dissolved oxygen in the root zone. But to achieve those levels, growers need to start with an even higher level of dissolved oxygen in a treatment system to deliver that 40-45 ppm to the roots. “Let’s say for example with 3 ppm of oxygen in the root tissue and 6ppm of oxygen in the surrounding soil or growing medium, higher concentrations outside of the tissue would help drive absorption for the root system membrane,” says Hayes.

Reaching that 40-45 ppm range can be difficult however and there are a couple methods of delivering dissolved oxygen. The most typical method is aeration of water using bubbling or injecting air into the water. This method has some unexpected ramifications though. Oxygen is only one of many gasses in air and those other gasses can be much more soluble in water. Paying attention to Henry’s Law is important here. Henry’s Law essentially means that the solubility of gasses is controlled by temperature, pressure and concentration. For example, Hayes says carbon dioxide is up to twenty times more soluble than oxygen. That means the longer you aerate water, the higher concentration of carbon dioxide and lower concentration of oxygen over time.

Another popular method of oxidizing water is chemically. Some growers might use hydrogen peroxide to add dissolved oxygen to a water-based solution, but that can create a certain level of phytotoxicity that could be bad for root health.

Using ozone, Hayes says, is by far the most effective method of getting dissolved oxygen in water, (because it is 12 ½ times more soluble than oxygen). But just using an ozone generator will not effectively deliver dissolved oxygen at the target levels to the root system. In order to use ozone properly, you need a treatment system that can handle a high enough concentration of ozone, mix it properly and hold it in the solution, says Hayes. “Ozone is an inherently unstable molecule, with a half-life of 15 minutes and even down to 3-5 minutes, which is when it converts to dissolved oxygen,” says Hayes. Using a patented control vessel, Hayes can use a counter-current, counter-rotational liquid vortex to mix the solution under pressure after leaving a vacuum. Their system can produce two necessary tools for growers: highly ozonized water, which can be sent through the irrigation system to effectively destroy microorganisms and resident biofilms, and water with high levels of dissolved oxygen for use in the root system.