Deborah Agboola   |   April 23, 2021

Extracting Terpenes - The Technology of Taste & Smell

Many therapeutic phytocannabinoids have been successfully isolated, but the terpenes have proven a tad more elusive.
Deborah is an inquisitive writer with a forte in technical writing. Her desire to enlighten and inform gives her the extra edge of structuring her writes to an easily understandable form, while retaining its technicality. When she is not…

The modern cannabis consumer doesn’t rely solely on whole-flower consumption anymore. The average cannabis consumer – medicinal or recreational – is aware of the medicinal and therapeutic benefits of cannabinoids and terpenes and desires preserved profiles, convenience, precise dosing, and discretion. These have been the aim of most cannabis-inclined industries.

Though isolating and crystallizing most phytocannabinoids has been successfully achieved through relatively simpler methods, these techniques do not serve the elusive terpenes due to their unique nature. As a result, most market cannabinoids contain terpene chemovars distinctly different from the parent plant.

The Challenges with Terpene Extraction

In the past, cannabis farmers modified conventional extraction methods to extract terpenes. However, outputs were mostly sketchy terpene profiles due to the considerable loss of the compounds and a high level of contamination.

Their unique and highly volatile nature always presented more challenges to the extraction process than most cannabinoids. Unlike the thick resins, heavy oils, alkaloids, and others that can be successfully extracted using somewhat common methods, terpenes require more assiduous methodologies to isolate and extract due to their high heat susceptibility.

Still, some of these techniques have proven more effective than others.

Steam Distillation and Hydro-distillation

These two are among the more traditional methods of terpene extraction, having been in use for centuries. In steam distillation, the lighter oils are solubilized in the steam and then condensed for collection. On the other hand, hydro-distillation involves the direct placement of the stock material in boiling water.

Nevertheless, both cases involve extreme heat use and are therefore not practical for preserving original terpene profiles. The vaporization of these highly volatile compounds often results in a low yield; the latter demerit a factor in water-soluble compounds, consequent in the formation of hydrosols.

Solvent Extraction

Another of this kind is solvent extraction, using hexane, CO2, or hydrocarbons. Of the lot, hexane and other water-insoluble solvents are more cost-effective but not recommended for food-grade extraction. Some also augment the rapid vaporization of terpenes.

Similar to the standard extraction process, CO2 extraction is highly favorable for food-safe terpene extraction. However, unlike these cases, terpene extraction is optimal when the CO2 is at its sub-critical state.

The sub-critical state consists of lower temperatures and pressures than the supercritical. In this state, essential oils (low molecular weight molecules) are optimally obtained.

Using a supercritical-CO2 extractor, a subcritical run can be carried out by conducting a short, light run of the machine.

Nevertheless, this procedure is mainly limited to dry flower extraction because the high moisture content in fresh flowers might lead to acid production.

Extracting Terpenes with Modern Technology

Fortunately, advancement in technologies has brought new modalities through which natural terpene profiles can be preserved and utilized. The selection of a process is appropriately subject to judgment through various factors, ranging from polarity, volatility to size.

Of the many discovered and yet developing technologies, a few raced ahead of others, rapidly advancing and gaining popularity within the cannabis niche:

Emission Trapping

Terpenes are naturally emitted from plants. Hence, scaling up this order, nature is blended with revolutionary science. This was conducted in an experiment at the Department of Pharmaceutical Sciences of the University of Kentucky, Lexington, during which terpenes were effectively extracted from the resin.

The conducting scientists created a set-up involving a live plant placed in a gas chamber with an air inlet and a vacuum line serving as an air outlet from the chamber. Outgoing gases – vaporized terpenes inclusive, were then passed through a tenax resin-packed pipette to trap the terpenes. The pipettes were replaced every 1-4 hours, and the terpenes pulled from the resin using a solvent.

Considering the advantages, this method is generally cost-effective, efficient, easy-to-practice, and eco-friendly. It can also be used in obtaining food-grade terpenes with excellent profiles when conducted according to standard.

However, on the downside, emission trapping is not a practical option for large-scale/commercial extraction, as the emission effective ratio is relatively low.

Solid-phase Microextraction (SPME)

The principle behind this process is the simultaneous extraction and enrichment of desired analytes from a given matrix in a single step. This process is considered effective and efficient, with little to no need for organic solvents and other time-consuming procedures.  

In extracting terpenes, the target compounds are obtained from the matrix via a fiber-coated extractant. While extra mechanical action might be required in some instances, the primary benefit of this procedure is its solvent-independent processes.

To obtain the final isolates, the extracted terpenes contained in the fiber material are placed in a gas chromatography chamber, which then pulls the terpenes from the fiber and collects them.

This method is also used in qualitative and quantitative analysis of terpenes, offering a cost-effective and more efficient means in both cases – analysis and extraction.

Ultrasonic Extraction

Notably, sonication is one of the most excellent ways of producing high-yield terpenes. Studies have established that terpenes such as β-caryophyllene oxide and α-pinene can be successfully extracted through sonication or sound energy.

Sonication ensures a high mass transfer between the cell-matrix and the solvent, which is often a small amount of ethanol. Thus, due to the primary dependence on sound energy and minimal solvent use, it offers many advantages, like environmental safety, efficiency, ease-of-use, and health safety.

Bringing Science to Market

Abstrax™ is a cannabis-inclined company focused on botanical extraction, terpene, and aroma compound research. Using advanced chemovar analysis and other revolutionary technologies, they claim to create unique, botanical, and non-cannabis-derived terpene formulations that resemble original flower aromas. Recently the company announced their terpene products are now available on Weedmaps Exchange for companies interested in purchasing natural terpenes for their product formulations.

While the industry has gone a long way in obtaining pure, full-spectrum terpene profiles, in some cases, the whole is not always whole, even with processes that tout full-profile extracts. Hence, the industry’s research and development sector is working on creating laboratory-synthesized but essentially organic terpene formulations; profiled from botanically derived terpenes.

 

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