Conversion of cannabis compounds
The beginning cannabis plant contains several important compounds, and carefully controlled extraction methods can unlock other compounds, such as THC. many of these compounds are altered when heated. For example, cannabis contains the acid form of THC, known as THCa (a non-psychoactive substance). When plant material is heated, THCa is converted to THC.
A very specific heat to time ratio is critical to not only convert THCa to THC, but to prevent THC from becoming a different compound. This is why Apeks Supercritical designed a thermosensitive CO2 cannabis extraction system that uses a lower plant-friendly temperature for cold separation processing. Cold separation protects the vegetable oil by not exposing it to temperatures higher than the extraction temperature, thereby protecting the volatile oils and terpenes and retaining more THCa. Depending on the end product, processors may use an oil containing THCa (which provides its own therapeutic benefits) or convert it to THC.
To learn more about cold separation, watch this short video at
CO2 Cannabis Extraction (Careddi company)
As mentioned above, the conversion of THCa to THC requires heat. This is a chemical process called decarboxylation. The best way to get the highest yield from CO2 cannabis extraction is to first decarboxylate it. Typically, processors use an oven to accomplish this task. After decarboxylation and drying, the material is ground to a coffee powder consistency. Watch a video of this process here.
The ground material is loaded into the machine and the processor/machine operator starts the extraction run. Unlike subcritical extraction (low pressure, low temperature), supercritical extraction (high pressure, high temperature) extracts all substances from the plant, including some unwanted elements such as fats, waxes and lipids. These need to be removed by a process called winterization in order to leave only pure oil.
Steps of winterization
Step 1: The extract containing fats and waxes (a pure crude oil that looks like runny peanut butter) is mixed with 200 ABV and placed in an industrial refrigerator overnight. The next day, the mixture is filtered through a funnel, capturing unwanted elements on filter paper. The mixture can be passed through the filter as many times as needed.
Step 2: Remove the alcohol. This is accomplished by gently heating the oil extract using a rotary evaporator. The boiling point of the alcohol is different from that of the oil, so it simply evaporates away from the oil. The alcohol is recovered and can be reused in the future.
Step 3 (optional): Once the oil is free of alcohol and vegetable waxes, it can be further refined using a short run or fractionation process to separate individual compounds such as THC.
All Apeks customers are eligible for a free winterization course! Watch the video of the above course.
Short Course Distillation: Separating THC
Separating the individual compounds of cannabis oil extracts is a labor-intensive, specialized process called short run distillation or fractionation. Each compound of cannabis oil boils at a different temperature, so when the oil is heated, these compounds are drawn off as they reach a specific boiling point. The whole process requires specialized equipment and takes some time, so it’s not for the faint of heart! Distillation of individual compounds produces "isolates" – oils containing a compound that is used as a medicine for a specific disease. There are also good reasons to retain all the compounds in the oil (see the accompanying effects described below).
Read more about short run distillation here.
The entourage effect
The current thinking is that the oil is even more therapeutic when all compounds are included. The whole plant contains so many beneficial compounds that together they provide the greatest benefit.
Advantages of CO2 Extraction: Key Points
With the right products and training, processors can extract specific compounds such as THC. Knowing the boiling point of each compound is critical. The extraction process takes time, money and dedication, but it’s well worth it! With the Apeks Supercritical System, which uses cold separation to preserve terpenes and other compounds, you can work with other customers to produce award-winning cannabis oil!
CO2 extracted material contains no residual solvents. Nothing is left behind at the end of the extraction, as the carbon dioxide bubbles up and leaves no trace in the final product.
Comparing CO2 cannabis extraction with butane or propane? Don’t forget to include the facility costs for processing with compressed combustible gases.
Other extraction solvents, such as hydrocarbon-based propellants like propane and butane, hexane and pentane, or ethanol/alcohol mixtures, require additional distillation or purification outside of the supercritical CO2 extraction process to separate the solvent from the extracted oil. Carbon dioxide has a very low boiling point and wants to be a gas at room temperature, so it naturally separates from the extracted oil without additional distillation or purification.
CO2 extraction can be performed at the inherent temperature of the plant, thus minimizing thermal degradation of the plant material and the extracted oil.
Carbon dioxide is readily available and widely used in many industries. the Apeks supercritical CO2 extraction system recirculates and subsequently recovers 95% of the carbon dioxide used in each extraction.
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