Oils, topicals, vapes, pills and edibles: As the market literally blossoms with alternatives to the standard joint and lighter, cannabis extracts are looking pretty sleek.
Colloquially referred to as “hash” or “kief”, depending on the context, producers and consumers alike have been known to employ expensive equipment and don safety gear to suss out cannabis’ raw potential as both a pain-easing healer and a perception-twisting stimulant.
However, precisely how cannabis extract makes its way from the dense, sticky leaves of its native plant to brownies, tinctures and creams hinges on what extraction specialists want out of it.
A cannabis cultivation advisor at Flemming & Singh Cannabis in Nova Scotia, Av Singh says isolating flower’s 100-plus known cannabinoids—the compounds that make up cannabis—is the reason companies are shelling out big bucks on high-end extraction equipment. “Cannabis extracts are usually synonymous with concentrates,” Singh explains. “We’re choosing the chemical compounds we want more of, and we’re eliminating the ones we don’t,” he notes.
As cannabis’ non-psychoactive cannabinoids are known to have a generally helpful effect on a user’s high—what’s called the “entourage effect”—it may seem curious that producers and consumers would be so keen to segregate compounds like THC and CBD from their company.
Singh explains that while the entourage effect might be well and good for those looking for the “full spectrum” benefits of cannabis, being choosier about those compounds lets consumers also be choosier about what benefits they’d like to receive; as not everyone’s up for a fit of couch-lock before heading out on a Monday morning.
“The public generally wants THC and CBD, but there’s over a hundred other properties that are also useful,” says Singh, adding there are likely more than 200 terpenes (essential oils in the plant) that promote a multitude of medical and recreational advantages outside of the two major players. Lesser-known, non-intoxicating cannabinoids like CBDA, THCA and CBN can also be pulled from the process.
The big names in modern cannabis extraction are typically limited to two methods: supercritical CO2 extraction and ethanol extraction.
Supercritical CO2 extraction
For CO2 extraction, an industry-standard unit is still often better for smaller batches than for mass production
“Supercritical CO2 extraction uses the temperature and pressure of CO2 to target and make available specific cannabinoids,” Singh explains. The bulk of the action in industrial-grade extraction systems (the types used by LPs) takes place in three components: the extraction container, the accumulator and the separator. Once the extraction vessel has been filled with ground cannabis, the accumulator charges the vessel with liquid CO2 until it reaches the pressure and temperature needed to obtain whichever compounds extraction specialists deem necessary, which the separator removes and isolates for use in any number of cannabis-derivative products.
(It’s important to note that the step-by-step process can vary from unit to unit.)
“It’s a difficult process,” says Singh. He notes that an industry-standard unit can cost anywhere from thousands of dollars to around $1 million alone, and is still often better for smaller batches than for mass production—though with the capital flowing through the cannabis sector, Singh expects that may not be the case for long. CO2 extraction is notable in its ability to pull out specific cannabinoids and terpenes, but at a cost.
“CO2 lets you dial in quickly and pull out lots of those specific compounds,” Singh reports, but adds that is “at the expense of not having full access to other things like CBD, CBN or THCA. For example, if THCA is what you want, you can get 70 percent of the cannabinoid pull to be THCA, and the rest will be other cannabinoids, terpenes and so on.” While this is good news for concentrates, extractors can sometimes pull terpenes if the unit’s set to a lower boiling point (known as “subcritical” extraction), he notes, adding that every chemical in cannabis has its own unique boiling point. Singh says that to fully separate the cannabis oil to its individual components (as with distillates and isolates) requires further processing via short path distillation.
Ethanol extraction method good for edibles and topicals, but not so much if looking to capture the flavour profile
Conversely, ethanol extraction tends to offer a more balanced representation of the plant while giving less in the way of particular compounds. Singh says it’s acknowledged to be a more efficient solvent than CO2, as it’s a bipolar solvent (having the ability to work with elements that both “like and hate water”), resulting in greater robustness in what it pulls out of a plant.
“You’ll have your container of bud, fill it with ethanol and let it extract for an hour or so,” describes cannabis researcher and plant breeder Ryan Lee, who is also founder of cannabis seed company Chimera Genetic Resource Management.
“When you remove the solids, you have the cannabinoids and terpenes in that bath,” Lee says. He explains that the ethanol is then boiled, which removes many of the compounds that boil at lower temperatures.
“The flavour in the terpenes may have boiled off,” he says. “It’s good for edibles and topicals (which are meant to blend with those products so as not to give a ‘weedy’ taste or smell), but not if you want the flavour profile.”
Singh suggests that the kind of ethanol extraction system an LP might use could be as expensive as a CO2-based unit, depending on vendor and technology, though perhaps slightly less so in most cases. Ethanol extraction is said to require a higher level of energy consumption than CO2 extraction, so it may be more suitable for large-scale operations.
CO2 or ethanol?
Cannabis researchers and extraction specialists are careful to note that, on average, what an extractor’s looking for will determine which process is a stronger fit for the operation—what makes one method “better” comes down to what the desired end product.