Distillation has been a critical step in preparing cannabinoid concentrates for years. The process purifies liquids by converting them to vapor and then condensing them back to liquid using temperature and pressure variances. However, cannabinoid distillation is quickly becoming obsolete due to more efficient technologies.
The magic of distillation has always been easy to see with cannabis oil. After all, we are turning plant matter into a thick, dark, crude oil and distilling it into a light, golden concentrate. This is especially true for extractors using ethanol and CO2 as solvents, which dissolve the plant’s cell walls to capture cannabinoids and terpenes deep inside the trichomes that hash-washing and rosin-pressing often leave behind.
The problem is when you dissolve plant cell walls, you also release a range of undesirable compounds like fats, sugars, lignin and chlorophyll. This makes crude oil thick with dark greenish-brown tones, and its harsh impurities are not desirable in today’s vape pens.
As extractors purify, they often convert the acidic THCA into a decarboxylated THC since that’s what produces the desired euphoric high. If one ate 1,000 milligrams of THCA, they would feel nothing, but if a person ate 1,000 milligrams of decarboxylated THC, they would likely end up “green sick,” which is no fun. The decarboxylation to THC is a simple process of breaking the carboxyl group and heating it for about two hours at 200 degrees Fahrenheit.
This brings up another critical industry misconception. As Kyle Michael, president of Follow The Leader Distribution Company, Canada’s leading distributor of ASCERA and AVEO premium vape hardware, said during a recent interview, “At the beginning of the boom cycle, delta-9 THC distillate was being sold for a premium price, and there developed a misconception about it offering a premium vaping experience. Yet it does not produce an enjoyable high.”
Now that the market has been diminished with oversupply, premium vaping oils are trading for less than what distillate traded for four years ago, he says.
“The additional time and expense to process distillate to get to a bottom dollar return is compounded by the fact that experienced vape users are seeking a fuller entourage effect through vaping higher-end oils,” Michael says. “Many premium vapes are being sold with THE (high-terpene extract) or terp sauce, oil formats that have not been fully decarbed. The portions of the formulation containing THCA are also more profitable. Since more than 12% of your oil weight is lost in the decarboxylation process, formulating vapes with some THCA content gives you close to a 13% better return on that portion of your extracted yield.”
Typical extraction processes start with a solvent soak to make crude oil, often followed by a bulk solvent recovery step. Next, the crude oil is dewaxed and decarboxylated to prepare for the distillation column. Crude oil starts around 50% pure cannabinoids, and processors aim for a purity of 85% to make it a sellable product. To achieve this purity increase, processors historically used distillation equipment.
First, a volatile stripping distillation pass is performed, followed by a second pass, which allows oils to reach the mid-70s in purity. Although some labs reach the mid-80s that second pass, a third distillation pass is often needed to obtain the desired mid-80s concentrations. A fourth pass might be employed to get into the 90th percentile, but extractors know each pass incurs huge losses. In fact, from crude oil to final distillate, processors will lose well over 50% of the original crude oil’s mass.
Extraction, solvent recovery, dewaxing and decarboxylation equipment are straightforward technologies compared to the complexities of distillation. Subsequently, it’s often the most expensive equipment in the lab — often, triple what the lab spends on the first few extraction stages to match throughput amounts. This is why distillation is usually the biggest bottleneck for most labs. They may extract 3 to 5 liters of crude per hour, but it is common to find they can only eke out 0.5 or 1 liter an hour of distillate, which may need more passes.
Beyond the losses and costs of distillation, there’s also time to consider. Since most labs can’t afford million-dollar multi-stage skids to match extraction output, they often extract one day and spend the rest of the week distilling. Then there’s cleaning and service time. Most extraction equipment cleans up in a few hours, but breaking down distillation skids to clean out hardened sugars and accumulated impurities while replacing wipers can take days. It is the most complex job in any lab and requires highly skilled staff.
The golden question is, can labs make purified cannabis extracts without the losses, complexity, costs and time required for standard molecular distillation equipment? The answer is unequivocally yes.
The first key is using an extraction process that is selective enough not to pull most of the impurities to begin with — processes that use highly efficient solvents that target cannabinoids and valuable terpenes, leaving most impurities behind. Light hydrocarbons, such as cold butane and propane, do just that, capturing the THCA and terpenes all in one shot. The purification process with THCA is crystallization, a technique older than distillation itself.
Even if you’re crystallizing and not distilling, you must remove the volatile organic compounds (terpenes) from the THCA to purify it further. This can now be done more efficiently using hydrocarbon membrane systems.
These membrane-derived (HTE) terpenes are unblemished by heat and can be captured for later use in vape carts, albeit the HTE will be about 30% THC. Then, the lab can simply crystallize the super-saturated THCA (making diamonds) into tiny crystals, not big diamonds. And remember, if you don’t decarboxylate, you end up with 13% more concentrate, which pure profit.
At this point, one only needs to decarboxylate the nucleated THCA crystals to make THC, and because these crystals are nearly 99% pure, this THC oil will also be nearly 99% pure. Better still, just use THCA crystals in carts and skip decarboxylating altogether. The only decarbed THC oil labs should need is what goes into edibles. Either way, there are no distillation losses or complexities to endure while saving expensive distillation time and costs. The bottom line: distillation is no longer required.
Finally, the terpenes are homogenized into the purified cannabinoid oil using a mixing centrifuge. The result is a more potent, better-tasting product worth much more at the retail counter. Ironically, this higher-quality end product also costs much less to make, which is an excellent recipe for higher profit margins.
Steven Fuhr is an extraction consultant with SciPhy Systems. He can be reached at SteveFuhr@SciPhySystems.com with any questions or comments.