In the cannabis extraction industry, ethanol is a popular solvent, particularly for large-scale hemp extraction, that can yield a fast and efficient throughput. However, this extraction solvent is rife with critical drawbacks, particularly creating a darker-colored extract.

Darker-colored, ethanol-based extracts can be a result of an excess of chlorophyll extracted alongside active compounds.

Ethanol-based extractions do not have to compromise on color and quality for fast throughput. A handful of homespun and advanced filtration techniques can help remove chlorophyll and reduce the oil’s dark green color to a golden amber oil that looks, tastes, and smells incredible.

Green as Grass: Plant Material at Work

Nature is known for its rainbow of colors. We recognize that the sky is blue, oranges are orange, and grass is green. Generally, most cannabis plants are recognized by their signature serrated leaves, vivid green foliage, and clusters of buds, but sometimes nature likes to mix things up.

Not all grass is green. In some cases, cannabis buds can display red, purple, or blue pigments. Let us take a look at the different pigments that give cannabis its vibrant color.

• Chlorophyll: Chlorophyll gives plants their green color and is critical in photosynthesis allowing plants to absorb natural light from the sun for energy.

• Anthocyanins: As a plant matures (and with certain environmental changes), the chlorophyll production is lowered and the anthocyanins reveal a cornucopia of bright colors such as striking purple buds. 

• Xanthophyll: Xanthophyll helps plants regulate heat and light and is visible as a yellow pigment.

Ideally, cannabis extractions remove only the active compounds (cannabinoids and terpenes) without the chlorophyll and plant waxes. However, all extraction solvents will extract chlorophylls, at varying rates.

Chlorophyll is not soluble in water. However, chlorophyll is highly soluble in ethanol, which is why it can end up in the extract leaving behind a bitter taste and darker tone.

Drawbacks of Using Ethanol as a Solvent

Despite its ability to extract active compounds from cannabis, ethanol can unintentionally pull out undesirable plant material such as pigments and waxes.

In this case, room-temp or warm ethanol in particular increases the speed and amount of dissolved chlorophyll compared to cooler temperature ethanol. Processors may use rotary evaporators (rotovaps) to purge the ethanol but they will leave behind the pigments and plant waxes.

One of the best ways to limit the extraction of chlorophyll is to use standard operating procedures that do not extract as much of this unwanted material.

Processors may limit the co-extraction of undesirables by using chilled ethanol (-20º C to -70ºC), and by shortening extraction time. Warmer temperatures can cause compounds like chlorophyll to be more readily dissolved.

When you want to reduce the solvent’s hydrophilic characteristics, cold ethanol is used. Super cold ethanol makes it easier to avoid pulling chlorophyll and waxes.

In the end, ethanol extraction is a balancing act of removing the most amount of active compounds while holding back the undesirables contained within the plant material. In particular, there are a few ways, some more sophisticated than others, to remove chlorophyll from an alcohol extract for clearer oil.

Color Remediation for a Clearer Extract

Nobody wants to buy dubious colored cannabis concentrates. If you do not want to sacrifice a high recovery rate for a golden oil, there are many color remediation techniques that can improve cannabis extract color post-extraction.

Using a variety of filter media, processors can literally pull out the undesirables leaving behind more translucent and light-colored extracts.

From low-cost and DIY remediation techniques that can be performed at home to automated systems for commercial use, the type of color removing technique depends on your budget, throughput needs, and desired quality. 

Distillation

One well-known technique to separate the chlorophyll is using distillation under vacuum.

During wiped film distillation, the extract is fed into a heated column with a rotating wiper blade that evenly distributes the extract onto the surface of the walls. Within the evaporation vessel, lies an internal condenser at the center.

As the oil is moved by the wiper blades down the walls of the column, the lighter components evaporate off of the heated wall and recondense onto the internal condenser back into a liquid. The purified liquid is collected at the bottom as a distillate. The unwanted, heavier materials that did not evaporate including chlorophyll and waxes are collected in a separate container at the bottom. 

A simpler short path distillation process does not use the wiper blade system. In this method, the extract material is fed into a heated flask then put under vacuum. The temperature is increased gradually and the different compounds will condense one at a time based on their weight. A skilled technician will be able to separate the good from the bad.

Activated Charcoal

For lab processors who want to remain competitive, one of the most effective and popular ways to remove chlorophyll from an extract is by using activated charcoal. 

Made from coconut shells, peat, petroleum coke, bone char, olive pits, coal, or sawdust, activated charcoal, also known as activated carbon, comes in the form of a fine black powder. It becomes active when processed at extremely high temperatures, which do the following:

• Change its chemical structure

• Increase its surface area

• Reduce the size of its pores

Compared to regular carbon, activated carbon is more porous.

In the health world, this treated substance is able to eliminate toxins from the body without being absorbed and is especially helpful in instances of poisoning. 

In the extraction process, activated carbon can similarly improve the color and taste of your extract without affecting its quality. 

In some cases, however, using activated charcoal can be a double-edged sword. While this substance is very effective at getting rid of unwanted pigments, it can do just as good a job at pulling out active cannabis compounds.

Activated carbon’s large pore diameter distribution and particle friability can produce a lower-than-desired yield.

In addition, as these natural elements break down over time with use, they can release a large amount of ash that contains heavy metals. In the worst cases, these heavy metals can seep into the oil as unfilterable particles.

More dangerously, using activated carbon can increase the risk of solvation and dissolution of benzopyrene in a cannabis extract. The carcinogenic benzopyrene compounds can be the result of combustion of bitumen or coconut.

As a medicine, cannabis oil with these contaminants can offset their therapeutic value of cannabinoids and terpenes if they leak into the extracted concentrate.

HEXANE

Hexane is another substance that can be used to separate chlorophyll from an alcohol extract. In this advanced method, an ethanol extract is dissolved in distilled water and then the lab-grade hexane is added to the water and then mixed and poured in a separation funnel.

Using this method, two layers will form. What is left is the upper hexane layer containing chlorophyll that will have a dark green color and then there is the bottom water layer. The aqueous layer and hexane layer can be collected in separate beakers.

To remove the minor traces of chlorophyll leftover in the aqueous layer, the wash is repeated until there is very little chlorophyll. 

Another way to create a chlorophyll-free extract is to re-dissolve the extracts in heated hexane and then continuously wash the mixture with saturated saltwater. In this method, table salt is mixed with hot water until all the salt has dissolved.

Afterwards, the saltwater and hexane may be poured into a separatory funnel at the same time and shaken well. The mixture is then allowed to “burp” before the solution’s layers are separated.

The bottom layer is bled off. The hexane is replaced and the wash process is repeated until the hexane has the clarity desired. Then, the hexane can be evaporated using a variety of purging techniques.

Media Bros Filter Media for BHO and CO2 Extraction

In the highly competitive extraction industry, a dark extract can be the least desirable outcome. While ethanol is more notorious for extracting chlorophyll alongside cannabinoids and terpenes, other solvents such as light hydrocarbons (butane and propane) and supercritical carbon dioxide (sCO2) can also yield dark extracts 

Compromise is important in relationships, but do not compromise any longer on color, flavor, and aroma.

A full line of Media Bros filter media for BHO and CO2 extractions is the solution to creating a golden-colored extract without the risk of contaminating the extracts.

• CRX: For inline hydrocarbon extraction, CRX is the industry-standard to remove colors while retaining the original cannabinoids and terpenes.

• CRY: Think CRX on steroids. CRY is a more aggressive approach for difficult-to-process materials. 

• CR2: Meant for use in CO2 extraction systems to improve the purity and look of an extract, and eliminate the bitter CO2 taste. 

If you are an ethanol extract producer looking for superior filter media to remove the unwanted plant material from an ethanol extract, your wish may soon be granted. Our engineers and chemists are working hard at bringing you a solution for ethanol extractions in the near future!

In the meantime, do not hesitate to contact us with any questions about our filter media and hardware. Founded with a scientifically engineered approach to improve existing extraction technologies, Media Bros is not only here to help but to give you the information you need to make informed decisions about things that matter most to you. 

Our team of dedicated professionals can help you troubleshoot your extraction workflow to achieve a better extract. Period.