Terpenes are all the rage for health, beauty, and recreation. But what’s the best way to extract these light compounds?
Interest in terpenes (or essential oils) in the botanical products industry has flourished in the past decade. This trend was ignited by the science of aromatherapy which produced promising research that particular scents from plants can be used to stimulate brain function and enhance psychological and physical wellbeing.
The promise of terpene science has also been popularized in the burgeoning medical cannabis field by two researchers, Dr. Ethan Russo and Dr. Justin Fischedick who maintain that the terpene profiles of different cannabis strains have an “entourage effect“. They have argued that terpenes work in combination with cannabinoids to account for the varieties of mental effects and medicinal benefits attributed to different types of cannabis.
Extraction of terpenes presents unique challenges because of their delicate and volatile nature.
Rosin on an Almond Tree, a salient example of terpenes in nature.
The Natural Wonder of Terpenes: Trees and Rain
As we delve into the different methods of terpene extraction which Eden Labs offers, it is useful to take a quick look at how important terpenes are in the function of the natural world. The most profound example is how trees emit terpenes to bring themselves rain. When a forest requires rain, and conditions are right, the trees are able to off-gas monoterpenes to seed the atmosphere in a way which allows water vapor to condense on the terpene droplet thus causing rainfall. Although this phenomenon occurs everywhere there are forests, it is most important to tropical forests. When tropical forests are cleared for agriculture, rainfall levels drop. Observers have often noted that rain clouds stop right at the line where the forest stops and cleared fields begin. No terpenes in the air means drought.
Extraction of terpenes presents unique challenges because of their delicate and volatile nature. Whereas thick resins, heavy oils, alkaloids, etc. can be successfully extracted using somewhat cruder methods utilizing combinations of heating, stirring, and pressurizing with organic solvents and/or water, terpenes require a lighter touch to isolate and extract without damaging them.
Traditional Methods of Terpene Extraction
The traditional methods of terpene extraction is steam distilling and hydrodistillation. Steam distilling involves suspending a basket of herb above a vessel of boiling water. The steam passes through the perforated basket and penetrates the plant material. Only lighter oils such as monoterpenes are soluble in the steam. As the terpene-entrained steam passes out of the top of the distiller it comes in contact with a cooled condenser which liquefies the water and oils. The lighter oils float on the surface of the water and are easily collected. There is usually a water soluble fraction of oil that stays dissolved and gives the water a milky look. This is called hydrosol and is generally the type of herbal extract used in shampoos and cosmetics when an herb is listed on the ingredients. Hydrodistillation is similar to steam distilling except that the herb is placed directly in the boiling water.
The main downside to these methods is the extreme heat involved. Boiling water is accomplished at 100C (212F). Many plant compounds are altered or destroyed at these temperatures. This means the harvested essential oil may not smell quite the same as the flower it came from, or the medicinal quality of the oil is compromised which is the case with Oregano oil, for example.
Soma Labs began working on a solution to this problem in 2004 when we collaborated with a well-known tobacco company. Their goal was to create low temperature steam, under vacuum, to strip certain constituents from tobacco. Soma Labs designed a vacuum steam distiller which could steam distill at 120F or 50C. The project was successful and we have offered this design ever since.
Today we offer commercial distillers of 15, 25, 100, and 500 gallons which can operate at atmospheric pressure or under deep vacuum. They are multi-functional extractors which can perform our proprietary “coldfinger” solvent distillation extraction, stirred reactor extraction, vacuum steam distilling and can be used to recover solvents or distill liquors as well.
Supercritical CO2 extraction is a high-tech method of extraction which is becoming increasingly popular due to the fact that it leaves no solvent residues in the finished extract. The method is tuneable meaning different temperatures and pressures yield different results. CO2 Extraction also allows for the possibility of fractionating whereby extracts of different molecular weights will drop out at different times or into different separation chambers.
Soma Labs’ CO2 extractors are uniquely suited for the purpose of terpene collection.
Soma Labs’ CO2 extractors are uniquely suited for the purpose of terpene collection. In a typical instance, the unit is run for between 15-45 minutes and then shut off. At this stage of the extraction, only the terpenes have gone into solution in the supercritical CO2 as they have the greatest solubility. They can be squirted out of the separator and collected. The extractor is turned back on and then the heavier oils and resins can be extracted over the next few hours. Soma Labs will soon be offering an automated version of this process.
Soma Labs will be launching a new extractor design in the near future which holds great promise in terpene extraction. Preliminary research shows that the fragrances derived from this method are richer, fuller and more authentic than extractions done by more conventional methods. This is a CO2 method but it differs in that standard CO2 extraction uses a pump to pressurize liquid or supercritical CO2 through a vessel packed with herb. In this method, the herb is pressurized with CO2 vapor and tiny droplets of liquid CO2 are gently passed through the herb.
More information on this groundbreaking new extraction technique will be released at a later date.