Medicinal Cannabis Extraction, Winterization & Filtration Stages

Medical Cannabis Extraction Techniques | Australia Cannabis Consultants and Engineers | GMP and Validation

PharmOut’s Medicinal Cannabis extraction consultants have considerable experience with various medical cannabis extraction designs and techniques that are used to separate the components of cannabis and remove them from the plant matrix.

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Our medical cannabis extraction consultants can guide you in the choice of alternative medicinal cannabis extraction designs and techniques to separate the cannabis plant materials into different chemical fractions. These techniques are often used to isolate specific target compounds; for example, at least 113 cannabinoids, including medicinal cannabidiol products and medicinal products containing tetrahydrocannabinol (THC).

Extraction room 360° panorama – drag the cursor around the image to view the layout, for full screen choose the icon in the bottom right corner.

Most common medical cannabis extraction techniques are as follows:-

Medicinal Cannabis alcohol extraction

Medicinal Cannabis extraction rely on the alcohol solvent, usually ethanol, “dissolves” the plant material, often the liquid filtered, finally the alcohol is removed by evaporation, there are international standards governing residual solvents in pharmaceuticals. One of the biggest challenges is the inherent polarity of these solvents —meaning it has a propensity to mix with water and dissolve water-soluble molecules like chlorophyll. Please note there are restrictions in the solvents that are permissible for pharmaceutical applications based on toxicological data, methanol, for example, is a class 2 solvent and the final product must contain less than 3000 ppm and a permitted daily exposure of 30 mg/day. Ethanol is a class 3 solvent, with much higher limits, read more here.

Carbon Dioxide Cannabis Extraction

Instead of using alcohol, this method removes cannabis components from the plant matrix with carbon dioxide. Here, though, high pressure and heat are used to turn the CO₂ supercritical meaning it is simultaneously like a liquid and a gas. Using a reagent of any kind can add cost and clean-up time, so various techniques should be considered, and one is CO₂ extraction.

The equipment cost for this method is orders of magnitude higher than alcohol extraction, but it produces higher yields and less valuable material is lost.
With the cannabis components extracted, the supercritical CO₂ goes into a condenser and turns into a liquid that can be filtered and used again. Consequently, a very little reagent is used. That makes this method economical to run and reduces the need to dispose of waste.

Hydrocarbon extraction

Using butane as the extraction solvent creates what is known as butane hash oil. To do this, the process starts with cannabis and liquid butane in a pressurized and heated system. By using evaporation under a vacuum, it is then possible to remove the butane solvent. The vacuum turns the butane from liquid to a vapour, making it easier to remove.

Solvent-free extractions

It is worth mentioning that more basic techniques also exist for preparing cannabis and extracting desirable components from the plant matrix. Kief, for example, can be separated from cannabis buds simply by grinding and sieving. These crystalline formations make up part of structures known as trichromes which are found on many plants, including cannabis. Cannabis trichromes are primarily protective structures produced by female plants when flowering. Their intense bitter taste and strong aromas render the plant unpalatable to herbivores and, they are also believed to inhibit some fungal growth. When separated from cannabis inflorescence, kief looks just like a powder or pollen. And, as cannabinoids and terpenoid production is particularly concentrated in trichromes this powder can be added to cannabis preparations to boost potency or consumed alone as a standalone product.

Traditional hash, or hashish, is another example of a solvent-free, more basic cannabis extract. Again, the idea is to separate the trichromes from the plant material as they contain the highest concentration of desirable compounds. Two main methods exist for creating hash, one involves taking frozen cannabis buds and breaking them into smaller and smaller parts over a screen. In the process, trichromes are separated from the plant and fall through the sieve and then pressed into blocks. The other primary method of solvent-free hash extraction involves using ice water to separate the trichromes from the bud. After drying they can then be pressed in a hash block.

Rosin has also become very popular over the last couple of years. Produced from flowers, hash or kief, rosin is a translucent substance typically with a sap-like consistency. It’s made by applying heat and pressure to the material you wish to extract from and results in a product that’s very similar to the more time-consuming, expensive and solvent-based butane extraction. Analytical testing has demonstrated that this simple approach effectively extracts cannabinoids and terpenes with absolutely no risk of leaving behind toxic residual solvents like butane. The simplicity of this approach is without a doubt its biggest draw.

A flat heat press machine is used to squeeze the material but at a specific heat and pressure and the extract is scraped off or ultrasonic is increasingly becoming a favoured option.

Page last updated July 31, 2019.