Commercial cannabis extraction is a fast-growing segment in the industry. Cannabis processing can convert raw plant material into a variety of cannabis products including extracts, edibles, vape oils, and topicals. Filtration is a critical step in creating a high-quality and safe product. 

Cannabis filtration produces a pure cannabis oil without contaminants or undesirable compounds like waxes, lipids, and chlorophyll. The result is an end product that tastes and smells incredible and only has the essential active ingredients of the plant.

What Is Cannabis Filtration?

One of the key challenges of creating a pure and potent cannabis oil is removing its contaminants such as undesirable plant particles, plant sugars, pesticides, debris, chlorophyll, waxes, lipids, and fats. Chlorophyll can cause a bitter flavor and speed up cannabinoid degradation, while waxes can create a sticky extract with a harsher hit.

The cannabis filtration process is an essential component of crude oil refinement after the primary extraction has been performed. Cannabis filtration refers to an in-line or a post-extraction process that improves the color, clarity, and purity of the crude extract using a variety of filter aid media. 

Similar filtration processes are used in other industries such as the production of cooking oils and wine making. In the wine industry, wine is filtered with enzymes and filters to remove bacteria and grape fragments. Similarly, cannabis extract filtration takes out the compounds that negatively affect the look and taste of the concentrate.

Depending on the extraction method used (ethanol, light hydrocarbons, carbon dioxide), processors will use a filtration system to remove the contaminants from the oil. Filtration processes can use ethanol as a solvent (winterization/de-waxing) and a variety of filter media to trap unwanted particles in the oil.

Start With a Clean Extraction Process

A major part of a successful filtration process is starting off with higher-quality biomass material and using a cleaner extraction solvent and process that does not need to be extensively or aggressively removed, which can end up hurting the yield and potency of the oil.

Cannabis material with minimal pesticides, contaminants, heavy metals, and residual solvents will need far less refinement of these fine particles and solvent removal. However, heavily contaminated biomass and oil will require more aggressive filtration. 

Using proper standard operating procedures with your specific solvent type should achieve your desired quality extract without excessive residual solvents. Low temperatures and solvent blends (i.e. butane and propane) can improve the quality of oil and require less time spent on filtration.

After the plant material has been processed, many workflows include winterization, a method that uses cold ethanol to remove lipids and fats. Inline de-waxing can reduce the amount of lipids and fats while the extract is within the system. Filtration of the crude slurry is the next step to remove the unwanted particles while ensuring the product has a high potency. 

Winterization

Winterization of cannabis oil is a crucial step in creating a refined and pure oil. Before distillation, the crude extract must undergo a winterization process to remove the lipids, waxes, fats, using cold ethanol in sub-zero temperatures. 

Removing these undesirable compounds can create a clearer extract with the highest cannabinoid content possible. Not to mention, removal of these compounds can create a smoother hit compared to the harsh experience when vaping or dabbing these plant particles. 

During the winterization process, the non-polar crude extract is dissolved in a polar ethanol solvent at sub-zero temperatures for at least 24 hours. In these freezing cold temperatures, the undesirable compounds naturally separate from the crude cannabis making them easier to filter out.

Processors may maintain sub-zero temperatures with the use of chillers, chest or walk-in freezers, or dry ice. Keeping the material at these temperatures for at least 24 hours gives the plant waxes and lipids enough time to coagulate and rise to the top. Filtration can occur with a layer of diatomaceous earth.

Filtration can be performed with the help of a vacuum to pull the coagulated material through the filter. Filtration must be a relatively fast process to ensure the compounds remain cool and they do not dissolve back into the oil.

Activated Carbon Filtration

Activated carbon filtration using activated charcoal can be performed on crude extract to filter out chlorophyll and other plant pigments, giving the oil a better taste, look, and aroma. In a process known as carbon scrubbing, an activated charcoal filter is used in a color remediation column to remove the dark green and brown colors from the extract.

Activated carbon has powerful adsorbent characteristics, making it ideal for water treatment. It can be made from a variety of sources with a high-carbon content. In its activated form, the carbon has a high porosity and large surface area where contaminants can get trapped.

In certain cases, room temperature and warm ethanol can remove a higher-than-average concentration of chlorophyll compared to colder ethanol methods and other extraction methods such as butane and CO2 extraction. Excessive chlorophyll can be remediated using carbon scrubbing. 

Cannabis Filter Media Types

Aside from using activated carbon for chlorophyll removal in extracts, post-processing can include a variety of other filter media to improve the purification of the final product, whether it is to remove chlorophyll, debris, waxes, lipids, and other contaminants from the oil.

Popular filter media used for cannabis oil purification include:

• Activated alumina
• Activated magnesium silicate
• Activated bentonite clay
• Activated bleaching earth
• Diatomaceous earth
• Silica gel

Many filter media are highly porous, allowing fine particles to get trapped inside these microscopic pores. Over time, the filter media will need replacement to avoid particulates from ending up in the final product.

How the Cannabis Filtration Process Can Affect Yield

Cannabis filtration, generally, has a net benefit for companies that use high-quality filter media, equipment, and processes. In less than ideal processes, whether it is a poor quality filter or malfunctioning equipment, the filtration step can affect the quality, potency, and volume of the overall yield. 

Volume

Generally, the cannabis extraction process and the filtration stage should not significantly affect the volume in the long run. Maintaining optimized standard operating procedures during the extraction and filtration stage can keep the volume of the yield about the same before filtration and after filtration.

Potency

Potency refers to the amount of cannabinoids present in the end product. During the extraction process, the potency of the material can be affected. During a high-quality filtration stage, the potency should not be significantly affected. In fact, filtration can actually produce a more refined product with high potency and no harsh contaminants that can dilute the potency. 

Cost

A comprehensive filtration system provides an overall better product quality but not without considerable investment in additional equipment, filter replacements, and training. In addition to the operational costs, labor time is increased due to the filtration that must occur on top of the primary extraction.

Media Bros: Color Remediation for Cannabis Extracts

Media Bros produces innovative color remediation technology for commercial cannabis extraction. No matter the quality of biomass or oil, color remediation using Media Bros filter media can produce a clear and more flavorful product while retaining a high yield of cannabinoids and terpenes.