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The Myth of Solventless Extraction

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Dr. George Stantchev
Dr. George Stantchev

PHD, MBA, MSEE, Entrepreneur and CEO of most innovative extraction technology company.

In order to understand the making of concentrates one should comprehend the principles of numerous extraction processes, as well as to understand post-processing and the standards of making concentrated products. This knowledge is hard to achieve only by reading the internet. Traditionally working for an extract manufacturer or lab has been the only way to learn, and even then, practical experience isn’t always assured. In this article we will provide you the information usually kept behind the scenes.

What is Solvent Extraction?

Cannabis oil is extracted from fresh, frozen, or dried and cured flowers using a variety of solvents. In an extraction lab, CO2, ethanol, butane, and propane are the most oftenly encountered solvents. What you need to know about selecting the right method is its extraction efficiency, quality, speed and what makes them safe to use with the proper equipment.

There are 2 main types of solvent extraction: ambient and liquified gas. Ambient extractions have been used for centuries originating back in roman times from the famous roman scientist Aelius Galenus. Those type of solvent extraction he introduced are typical water, ethanol and other solvent ways to extract and formulate over 150 remedies.  

The novel extraction methods include use of so called liquified gas extractions as CO2 and hydrocarbons where newly developed gasses are used to extract and provide pure ingredients without solvent residues. In general the liquefied gas extractions are faster and cleaner way to obtain vital plant ingredients in medicinal concentrated form.

What is Solventless Extraction?

Heat, pressure, or agitation are typical solventless extraction techniques to remove cannabis trichomes first and then the resin from the plant matter. Due to the fact that there is never a concern about leftover solvents in the finished product, these processes are considered to be the safest. Since the solventless extractions are pure mechanical extractions there is no selectivity in the obtained extract and almost always it needs to be purified before offered to a customer or incorporated into a product.

The mostly popular “solventless” extraction is also called bubble hash extraction. Bubble hash is a concentrate that is extracted using ice water. Millions of trichome glands that look like a granular brown sugar make up the bubble hash, which when squeezed together resembles the traditional hash. Since there is no selectivity on the ingredients the bubble hash resembles a conglomerate of wax, cannabinoids and terpenes with small amounts of chlorophyll that needs to be further refined before offered to the customer. 

The next step is pressing it under high temperature in order to melt the volatile compounds and separate the oil form of the cannabinoids. The high temperature converts the cannabinoids and loses most of the terpenes while keeping all the waxy content coming from ticomes into the extract and usually the press is not sufficient to deliver high quality raw material for formulating products. 

The waxy content is usually 5-20% into the extracted resin and further processing is required. As a third step the extract needs to be winterized in order to obtain commercial viable form. When further winterized the remaining terpene content gets lost and the entire solventless concept has been a myth.

What is Post Processing?

For some solventless extractions as well as all solvent-based extractions, post processing is necessary. Post processing, regardless of the extraction technique, is what distinguishes the many cannabis products, including wax, shatter, budder, distillate, isolate, and more. Typical post processing is winterization, filtration, distillation, chromatography and remediation. Usually each one requires a separate machinery even if the vendor tells you that it can be done in line. 

In order to estimate what type and how much post processing you need you need to know your prior process in detail. The limitation factors here are the selectivity of your process. The main plant ingredients are either oil based, water based or acid based and each process draws various mixtures of those. That is why the selectivity is important as it is a key part to deliver pure natural ingredients you can use in final formulations. 

Each solvent has specific selectivity that needs to be taken into consideration as example oils will extract oils, ethanol – acids and water – water based compounds. That is why the post processing is almost always a solvent process with the exclusion of distillation where the separation occurs based on a boiling point temperature. 

What are Residual Solvents?

The residual solvents of any concentrate product is one of the most critical areas to evaluate when identifying the safety of a concentrate product. Once the extract goes through a solvent extraction and post processing this solvents needs to be removed completely as there are critical regulations for residues in the final product. 

This battle is easily won by using liquified gas extraction methods as the gas is easily introduced and removed from the concentrate without leaving a residue. Although even in that case one needs to be aware of the aggressive nature of the gas used as some gasses easily create byproducts in the final extracts. As example the highly oxidative CO2 creates undesired acids, the butane hydrogenates the oils and creates undesired aftertaste. 

What is important to consider in this case is use of extremely inert gasses with low miscibility in oils and water that does not alter the natural organic plant molecules and at the same time are not anymore present in the final product. Such compounds are not very easy to go by but they exist and are used in extraction. As an example PURE5™ developed an extremely novel extraction and purification method utilizing aerosols that are extremely safe and inert gasses used for drug delivery. 

What are Terpenes and how are they affected during extraction?

Terpenes are aroma compounds that play a crucial role in the experience someone has when consuming a concentrate product. The terpenes are very volatile substances that are mainly concentrated in the flower and they emit fragrance even at ambient temperature, that is why they are very tricky to capture. They can be obtained best from fresh plants as a substantial part of them is lost in drying. 

There are over 3000 terpenes known in nature and cannabinoids in some way are considered as such as their structure contains a base carbon ring with a terpene tail. That is why extracting the cannabinoids and terpenes as a whole is the best way to preserve the natural plant potency and medicinal effect. Although only a few extraction methods can really preserve those all together, even more preserve them during the post processing.

In the efforts to preserve the botanical vitality and consistency of the plant resin PURE5™ introduced a novel liquified gas extraction and post processing that preserves the original terpene and cannabinoid profile not extracting the fillers in the plant that has no direct value in the final product. The process is performed at room temperature not stressing any of the precious oils in the mix and not creating by products as all other older technologies used. 

What is Chromatography?

Chromatography is a process in which a natural extraction is fractionated into individual or specifically grouped compounds. We are one of the leaders in the terpene extraction world when it comes to fractioning cannabis oil so that she can create consistent terpene and cannabinoid concentrates.

Chromatography is a very oftenly used process in chemistry where one or multiple solvents with different selectivity are used in order to separate the main compounds in the plant extract. That is usually done with a column packed with media and extract passing the column diluted in a solvent that is put in a state to activate that column. Of course after the extract with solvent passes through the column the solvent should be removed with no residue which requires another piece of machinery. 

Our view on chromatography is that this process is not required if you plan your process right to be selective from the beginning to the end and your resin is in a pure form even after extraction. The selectivity of the aerosol gas PURE5™ utilizes is extremely selective toward the terpene-cannabinoid mixture and not selective toward the acid and water based compounds that are not into the target mixture. 

What are the Concentrates?

The majority of flowers available in the US averages around 15-25% THC. However, concentrates after extraction average around 60-70% and the market is looking for concentrates between 60-99%. To achieve that there is a process of concentration but we also need to be conscious that when a product is concentrated, some compounds increase significantly, while others are removed.

There are also chemical and solventless methods of concentration. For example producing isolates most often solvents that are selective toward the filler compounds are used but not selective toward the main ingredient. As an example to make a CBD isolate hexane or pentane is used that does not dilute the CBD but dilutes the other compounds. The process is usually lengthy as it goes through multiple phases of concentration. 

In PURE5™ we believe that sufficient concentration can be achieved by solventless low temperature distillation and natural crystallization of compounds rather than utilizing aggressive solvents in the isolation of cannabinoids. The same way one can achieve 100% concentration of the terpenes without need of a solvent process that usually decreases the yield in times. 

Aerosol Extraction Lab

The PURE5™ process is simple and for the lab usually one piece of fully automated equipment is enough unless you need to go through producing concentrates. A safe and GRAS gas is run in a liquid phase at room temperature through the biomass and within 15-60 minutes you can obtain pristine natural extract that is a complete mixture of terpenes and cannabinoids. It is the purest form of natural extract exactly as appears in the plant with preserved vitality and enzymatic content.

aerosol extraction laboratory algorithm of usage

With PURE5™ the post processing is a simple separation of cannabinoids and terpenes by cycle,  time or temperature without the use of reactive solvents that change the consistency of the oils. You can create live resin, full spectrum oil, distillate, crystals or pure concentrated terpenes. Even our remediation equipment works without solvents and uses a natural conversion in between the cannabinoids. 

aerosol extraction process in steps block scheme

In conclusion the word ‘solventless’ used in the market terms is another over-stated term that really applies to the initial process but not necessarily to the product the customer gets. In PURE5™ we really create value on the experience and we created a process to preserve the naturality with high confidence. What is more important for us is to deliver a pure natural experience to the customer without altering the taste or strain consistency by chemicals and heat. We treat nature gently in order to draw most benefits from the gifts we receive from the botanicals. 

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