Edward Clayton 
Tetrahydrocannabinolic acid (THCA) is a nonpsychoactive cannabinoid present in both raw and live cannabis. It is the precursor to tetrahydrocannabinol (THC), which is recognized for its psychotropic properties. Extracting THCA can be complex, involving various methods that each offer distinct advantages and challenges.
This article explores several techniques to extract THCA, detailing the processes and their benefits.
Solvent-Based vs. Solventless Extraction
Solvent-based extractions employ chemicals to dissolve cannabinoids and terpenes from plant material. This method employs techniques such as butane hash oil (BHO) extraction, ethanol extraction, CO2 supercritical extraction, and others.
In contrast, solventless extraction methods avoid the use of chemicals. They use mechanical techniques to extract the cannabinoids from the plant material. This category includes techniques such as rosin pressing, dry sifting, and ice water hash.
In summary, solvent-based extraction methods are known for their efficiency and ability to produce high-quality extracts but involve handling potentially hazardous solvents. Solventless methods provide safer, natural alternatives that preserve cannabinoids and terpenes but may be more labor-intensive and yield lower quantities.
Regardless of the extraction method chosen, the end goal should be to produce high-quality cannabis. As stated by Sluggers Hit, the extraction method should ensure purity and potency. Not adding any synthetic agents during the extraction can give a natural product.
Consider the example of live resin and live rosin. Live resin is a solvent-based extraction method, whereas live rosin is solventless. However, both methods can help extract THCA while retaining its characteristics and aroma.
Thus, the quality and premiumness of cannabis products depend highly on the extraction method used. Such premium products can be available with online retailers or nearby dispensaries where you can inquire. For premium cannabis products, including high-quality flowers and oils, click here.
Solvent Based Extraction
Solvent-based extraction uses chemicals to dissolve the cannabinoids from the plant material. These methods are popular for their efficiency and the high-quality extracts they produce.
Butane Hash Oil (BHO) Extraction
Concentrated THCA is often produced using BHO extraction. Cannabinoids and terpenes are dissolved in butane, which is passed through cannabis material during the process. The butane in this mixture is subsequently removed, frequently with the use of heat and vacuum, to yield a viscous, strong extract.
BHO extraction is valued for its ability to retain terpenes, resulting in tasty and fragrant extracts. However, the use of butane poses safety risks, necessitating careful handling and proper equipment to prevent explosions and ensure purity.
Ethanol Extraction
Ethanol is a polar solvent that may successfully extract cannabinoids and terpenes from cannabis. The technique includes immersing the plant material in ethanol, which dissolves the required chemicals. This solution is then filtered and evaporated to remove the ethanol, leaving behind a concentrated extract.
Since ethanol may be employed at room temperature and is less flammable than butane, ethanol extraction is acclaimed for its efficiency and safety. Ethanol is also food grade. Thus, it may be used to make edible and medicinal cannabis products.
A study from MDPI found that significantly lower CBD content was extracted with only 20% ethanol content. On the other hand, higher ethanol solvent (40% and 80%) helped extract more concentrated CBD. Here are the results of the study done to find how much CBD content is extracted with different amounts of ethanol solvent:
- 20% ethanol solvent: 0.063% was extracted from Tygra and 0.081% in Futura 75
- 40% ethanol solvent: 0.535% was extracted from Tygra and 0.557% in Futura 75
- 40% ethanol solvent: 0.952% was extracted from Tygra and 1.305% in Futura 75
CO2 Supercritical Extraction
CO2 supercritical extraction (SC-CO2) utilizes carbon dioxide in its supercritical state, where it exhibits the properties of both a liquid and a gas. This method is highly efficient and can be finely tuned to extract specific cannabinoids and terpenes. The process involves pressurizing CO2 and passing it through the cannabis material.
The cannabinoids are dissolved into the CO2, which is then depressurized to separate the extract. It is depressurized at pressures and temperatures higher than its critical points, which are 31.3°C and 72.9 atm.
This causes CO2 to present the properties of both a liquid and dense gas at the same time. Hemp seed oil may be extracted using (SC-CO2), which yields more tocopherols and less pigment than extraction using other methods.
CO2 extraction is regarded as one of the cleanest processes since it leaves no residual solvents in the finished product. It is also versatile, allowing for the extraction of a wide range of compounds.
Solventless Extraction
Solventless extraction methods avoid the use of chemicals, relying instead on mechanical means to separate cannabinoids from the plant material.
Rosin Pressing
Rosin pressing is a common solvent-free method for extracting cannabinoids by heat and pressure. Cannabis material is sandwiched between parchment paper and pushed against a hot plate, allowing the resin to flow out. This process is easy and requires minimum equipment, making it suitable for home extractors.
Rosin pressing maintains the entire range of cannabinoids and terpenes, resulting in a powerful and tasty extract. However, the yield may be lower than that of solvent-based approaches, and the procedure might be labor-intensive.
Ice Water Hash
Ice water hash, also known as bubble hash, separates trichomes from cannabis content by agitating it with ice and water. The procedure is soaking the cannabis in freezing water and then swirling it to agitate the trichomes. This causes the trichomes to break off and settle to the bottom. The mixture is then passed through a succession of mesh bags to capture the trichomes.
Ice water hash is a gentle approach for preserving cannabinoids and terpenes, resulting in a high-quality extract. It is also solvent-free, ensuring safety and environmental friendliness. However, it can be time-consuming and requires specialized equipment to provide the best results.
Ultrasound-Assisted Extraction (UAE)
Ultrasound-assisted extraction is a cutting-edge approach that uses high-frequency sound waves to improve the extraction of cannabinoids and terpenes from cannabis. This technique makes use of ultrasonic energy to induce cavitation bubbles in a liquid, usually ethanol. These bubbles implode, generating intense pressure and shear forces that break open the plant cells, releasing the desired compounds efficiently.
Operating at low temperatures, ultrasound-assisted extraction preserves the delicate structures of cannabinoids and terpenes, ensuring a high-quality extract. Additionally, this method requires less solvent compared to traditional extraction techniques, making it both cost-effective and environmentally friendly.
According to an NCBI study, the UAE and MAE process has been found to be very effective in extracting phytochemicals from cannabis. However, efficacy might vary depending on a variety of conditions. For example, solvent type, sample size, the ratio at which they are mixed, time, and power can all influence the effectiveness.
Microwave-Assisted Extraction (MAE)
It uses microwave radiation to heat the plant material and solvent, which accelerates the extraction process. Microwaves vibrate the water molecules within plant cells, generating heat and pressure that ruptures the cells and releases cannabinoids.
MAE is a quick and effective process for extracting large amounts of cannabinoids. It also functions at lower temperatures than traditional heating techniques, protecting the purity of cannabinoids and terpenes. However, MAE requires specialized equipment and careful control of the microwave power to prevent the degradation of the compounds.
Frequently Asked Question
What is the method of cannabinoid extraction?
There are different methods available, including solvent-based and solventless. A manufacturer may use any of these products unless they are patented. For example, patent US9199960B2 (Ivanov, 2018b) mentions a method where the plant is frozen for 24 hours before decarboxylation. Then, it is dried, ground, and then soaked in a solvent for at least a day.
What is the ultimate solvent for cannabis extract?
Because ethanol does not require high-pressure extraction and contains both polar and nonpolar components, it may dissolve both hydrophilic and hydrophobic compounds. For these reasons, most people believe that ethanol is the safest and best cannabis solvent available.
Is solventless cannabis better?
Most people agree that solventless extracts are the cleanest and most delicious cannabis extract that is currently accessible. Additionally, compared to ordinary extracts, they include a greater variety of terpenes and cannabinoids, which can result in a more varied and well-rounded high.
Extracting tetrahydrocannabinolic acid from cannabis involves a range of techniques, each with unique benefits and challenges. Solvent-based methods like BHO, ethanol, and CO2 extraction are efficient and produce high-quality extracts but require careful handling of solvents. Solventless methods, such as rosin pressing and ice water hash, offer safe and natural alternatives but can be labor-intensive and yield lower quantities.
Advanced methods like UAE and MAE provide rapid and efficient solutions, though they require specialized equipment. Understanding these techniques allows producers to select the most suitable method for their needs, ensuring high-quality THCA extracts for various applications.
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