Extraction techniques are used to separate the components of cannabis and remove them from the plant matrix. Various methods can handle cannabis plant material to separate the active ingredients from the undesirables such as fats and waxes. They have two main cannabis extraction methods: solventless and solvent-based techniques.
Solventless: Solventless extraction techniques do not use chemical solvents such as butane, alcohol, or CO2 but instead use a variety of agitation methods as well as machines that use low heat and pressure to break off or melt the cannabinoid trichomes from the cannabis material. Now there are two solventless extraction methods: bubble hash and rosin.
Solvent-based: Solvent-based extraction techniques use a volatile chemical to dissolve the trichomes from the rest of the cannabis plant matter to produce potent cannabis oil. After the separation process, the solvent is removed through a purging process, leaving behind a concentrated final product without the plant material. Three mainstream extraction methods in the market: hydrocarbon extraction, CO2 extraction, and alcohol/ethanol extraction.
This article will help you understand two of these methods of cannabis extraction – CO2 Extraction vs Rosin Press
Rosin of Cannabis Buds
Produced from flowers, hash, or kief, rosin is a translucent substance typically with a sap-like consistency. The rosin press combines heat and pressure to express the resinous oils from cannabis flowers, bubble hash, and/or sift, it’s to use temperature to target specific compounds during the press, including both terpenes and cannabinoids. Undesirable compounds, like waxes and plant matter, are held back using micron filtration bags. Analytical testing has demonstrated that this simple approach effectively extracts cannabinoids and terpenes with absolutely no risk of leaving behind toxic residual solvents like butane.
The heat and pressure extraction resulting in sticky, dark, and potent oil is called rosin. Rosin can be consumed as a dab or be infused into a variety of products including edibles, tinctures, and topicals. Live rosin is another form of rosin, which uses fresh frozen buds for a better flavor and aroma.
Extraction process
With rosin pressing systems, low heat, and pressures are used to melt and squeeze the sticky resin from the plant material (kief, trim, buds). The process is similar to how olive oil is made. During the olive oil production process, the extraction systems break the plant’s cells and release the plant’s oils for consumption.
Rosin press using similar to a panini press or a t-shirt heat press, cannabis is placed in between two heated surfaces and the press is then closed, squishing the terp-filled rosiny goodness from the bud. The rosin can have similar potency and greater terpene content than any solvent-extracted concentrate, this rosin extract is completely clean of residual solvents.
On a smaller scale, cannabis users can use a simple hair straightener and some cannabis buds to literally squeeze out the resin using pressure and the hair straightener on the lowest heat setting. Just place the cannabis buds in the paper and squeeze the bud in the straightener until it releases the rosin. Then remove any leftover plant material from the rosin. While it will not produce as high-grade extracts as commercial rosin extraction, it can provide users with a concentrated and potent product.
Four benefits of rosin pressing:
- Easy: Rosin pressing is relatively simpler to perform than solvent-based extractions.
- Safe: No risk of explosions at home or in the lab.
- Versatile: Producers can alter the heat and pressure to create solventless extracts in a variety of consistencies and colors.
- Quality: The highest quality concentrates are created through rosin pressing.
Three extraction methods for rosin extracts
Enthusiasts can produce highly potent rosin extracts with a hair straightener, some baking parchment, a collection tool, and, some heatproof gloves.
Commercial rosin presses are also available to process material on a much larger scale but the concept is essentially the same.
A flat heat press machine is used to squeeze the material but at a specific heat and pressure and the extract is scraped off.
Supercritical CO2 Extraction
Supercritical CO2 fluid has been in a pressurized environment. The carbon dioxide fluid is pumped across cured cannabis to extract active plant ingredients, such as THC and CBD. The beauty of supercritical CO2 fluid extraction is that the solvent itself can be placed in different states of matter (i.e. solid, liquid, or gaseous), to perform targeted extraction–“fractioning”– of various cannabinoid compounds and terpenes. The supercritical fluid CO2 passes easily through the plant matter and gently dissolves the membrane of the trichomes, thus extracting the various active compounds that naturally occur in marijuana. Read More: Supercritical CO2 Extraction Process: Basics, 7 Advantages, 7 Features, 4 Applications
7 features of the solubility of supercritical CO2 fluids
In the supercritical state, the solubility of CO2 for different solutes varies greatly, which is closely related to the polarity, boiling point, and molecular weight of the solute, and generally has the following features:
- Lipophilic, low boiling point components can be extracted below 104KPa (about 1 atm), such as volatile oils, hydrocarbons, esters, ethers, and epoxides.
- Aroma components from natural plants and fruits, such as eucalyptus brain, muscimol, low boiling point esters from hops, etc.
- The more polar groups ( such as -OH, -COOH, etc.) of a compound, the more difficult it is to extract.
- The extraction pressure of strongly polar substances: sugar and amino acids should be above 4×104KPa.
- The larger the molecular weight of the compound, the more difficult it is to extract.
- Components with molecular weight in the range of 200-400 are easy to extract, and some low molecular weight, volatile components can even be extracted directly with CO2 liquid.
- High molecular weight substances (such as proteins, gums, waxes, etc.) are very difficult to extract with CO2.
CO2 Extraction vs. Rosin Press
- No Chemical Residuals: Rosin extraction is a solventless method not use chemical solvents such as butane, and alcohol, this rosin extract is completely clean of residual solvents. CO2 extraction uses CO2 gas as a solvent, the gas will be fully removed, so the CO2 extract same leaves no chemical residuals in the final product.
- Essence and Flavours: Rosin extraction can great at retaining the essence and flavors of the source flower. Because the low heat and high pressure of rosin pressing preserves the flavor, the terpenes, and the potency of extracts.
CO2 Extraction can preserve valued secondary compounds like terpenes and flavonoids. But in terms of terpenes, it is not as comprehensive as rosin.
Rosin gives you the ‘entourage effect”, this is more terpenes in concert together, to give you a deeper and more complete ‘sensation” than CO2 extracts. - Flavor and freshness: The CO2 extraction method is only viable for dried cannabis and not fresh frozen because it uses temperatures above freezing that would melt the frozen buds, so its flavor and freshness are not as good as rosin.
- Cost: The smallest CO2 extractor can cost thousands of dollars. A small CO2 extraction machine for laboratory use also costs 20,000 to 30,000 US dollars. A rosin press is a very low investment in comparison.
- Extraction scale: As long as you are willing to invest in this point, the scale of the CO2 extraction machine can reach a large number, and the capacity of a single CO2 extraction vessel can be as high as 3000L.
Combined use of CO2 extraction and rosin press to extract cannabis
Rosin presses don’t do very well with trim and the amount of trim from a cannabis plant can be the same, or more, than the weight of the flowers, this means the rosin process, on its own, is an inefficient extraction method; so the rosin process leaves behind a lot of the cannabinoids in the post-pressed “chip” (sometimes referred to as a “wafer” or “puck”).
As often as not, these post-pressed chips get thrown away, fed to the dog, soaked in coconut oil to make an edible base, or soaked in alcohol to make tinctures. None of these post-press products are “capable” or easily “doable”.
Now put a small-scale CO2 extractor in the loop in combination with the rosin press (CO2 extraction is also considered a “solventless” extraction process and leaves zero residues in the extract). For a rosin-only operation that generates a significant amount of chips, when these two processes are combined, the first step can be to “rosin press” while at the same time, the trim from the plant is extracted directly into vape oil by the CO2 extractor. The “icing on the cake” is when the post-pressed, depleted rosin chips are put into the CO2 extractor. The amount and quality of potent, terpy oil recovered is nothing short of amazing. This oil is “capable” right out of the extractor and feeds the fastest-growing segment of the cannabis market.
Conclusion: by using a small-scale CO2 extractor in combination with a rosin press the operator can maximize the economic potential of the cannabis plant.
Works Cited: The 5 Most Common Cannabis Extraction Methods
The benefits of using small-scale CO2 extractors in combination with rosin presses.
