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supercritical CO2 fluid extraction process
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What is the supercritical CO2 fluid extraction process?
What is supercritical fluid extraction?
Among several supercritical fluid (abbreviated SCF) technologies, the earliest developed, most researched, and industrialized product technology is undoubtedly the supercritical fluid extraction (abbreviated SFE) technology.
Supercritical fluid extraction (SFE) is the process of separating one component (the extractant) from another (the matrix) using supercritical fluids as the extracting solvent.
Application of supercritical fluid extraction
Supercritical CO2 extraction (SCFE) is used particularly in the food, beverage, cosmetics, and pharmaceutical industry for extracting natural substances, aromas, fats, oils, waxes, polymers, enzymes, and colorants in their supercritical physical state.
CO2 is a natural and environmentally-friendly solvent that has advantages over synthetic and harmful media such as n-hexane when it comes to sustainability.
Why use the carbon dioxide extraction method?
Carbon dioxide is the most common compound used in high-pressure extraction. It boasts a number of benefits compared to other solvents used for botanical extraction.
For starters, carbon dioxide is a non-toxic substance that is readily available commercially for lower costs than other chemical alternatives. In addition, carbon dioxide is environmentally safe, and straightforward to work with, and it creates a superior product typically free of any by-products or residue. Temperature, time, flow rate, and pressure can be manipulated to enable the precise extraction of specific plant compounds.
Principle of the CO2 extraction process
Supercritical fluid extraction uses a supercritical fluid as the separation medium (extractant) and uses the fluid to have a highly enhanced dissolving ability in a supercritical state to achieve effective extraction of certain components (solutes) in the raw material, and then pass the temperature and the continuous adjustment of the pressure can reduce the density of the extractant, that is, reduce its solubility to the solute, so as to achieve high-efficiency separation of specific components in the raw material.
Advantages of CO2 Extraction Method: Key Takeaway
Because supercritical fluid has excellent mass transfer characteristics of gas and solvation ability equivalent to liquid solvents, supercritical fluid extraction using it as a separation medium is considered to integrate the two-unit operations of distillation and liquid-liquid extraction to a certain extent.
The advantages of this form a unique separation technology. The basis of the theory is the phase equilibrium relationship of the fluid mixture in the supercritical state, which operates in the mass transfer process.
CO2 extracted material is free of residual solvents.
Nothing is left behind once the extraction is over since the carbon dioxide bubbles away, leaving no trace in the end product.
Comparing CO2 cannabis extraction to butane or propane? Don’t forget to include the facility costs for processing with compressed flammable gas.
CO2 extraction is often used in the extraction of plant essential oils
supercritical co2 extraction method
The most commonly used supercritical fluid in the supercritical fluid extraction process is SC-CO2, and the products obtained by supercritical CO2 are mostly a mixture of volatile oils, greases, alcohols, ethers, esters, resins, and other lipophilic chemical components; The size of the extraction system will vary depending on the batch size. Samples can be as small as 10 grams, and as large as hundreds of kilograms. Some systems have the option to be automated, so the producer does not need to be present during the batch. Supercritical CO2 extraction takes longer to complete than other methods, due to the continuous fluctuations in temperature and pressure. For example, the extraction of 20 lbs. of plant material can take 4 to 6 hours.
how does co2 extraction work?
To perform an extraction, the plant material must be ground and placed into an extraction vessel. CO2 gas undergoes high temperature and pressure. A pump then forces supercritical CO2 into the extraction vessel where it meets the plant and breaks the trichomes allowing it to dissolve part of the plant material. A pressure release valve then allows the material to flow into a separate vessel, where an internal compressor and heater are used to adjust pressure and temperature. By changing the temperature and pressure as well as flow rate, certain molecules will bond to CO2, allowing them to be separated from the plant. Many systems will reroute CO2 back into the tank to be used during the next batch. The extract is then moved to a collection jar, such as a beaker.
Step 1: Biomass drying
Biomass (flowers, leaves, seeds, rhizomes, etc.) is much easier to buck when it includes less than 10% moisture.
A dryer will dry large volumes of material. Drying equipment employed in this case can include fluidized beds, rotary kiln dryers, or belt-driven infrared dryers.
As an alternative to machinery, many farmers let their crops dry in the field. This works well as long as the harvest time is cool and dry.
Step 2: Grinding
Once the biomass has been dried, it is granulated. In general, smaller particles (200-1000 microns) are desirable and tighter particle diameter distributions are better for extraction throughput. Several kinds of mills are available on the market to accomplish these goals including hammer mills, shear mills, and cone mills.
Depending on the desired processing volume, a typical grinding operation will include a hammer or a cone mill. The mill is assisted with vacuum cyclone collection.
Important: Before grinding (pulverizing) large chunks of biomass, it needs to be divided into flakes and sent to a pulverizer for grinding. This avoids the high temperature generated by the high-speed pulverization of biomass in the pulverizer, which destroys the characteristics of the extract and loses part of the essential oil.
Step 3: CO2 extraction
- Load extraction vessel with biomass.
- Bring each vessel to working pressure using CO2 from supply cylinders.
- Create supercritical CO2 fluid.
- Alter pressure and temperature, depending on what’s being extracted and the goals of the extraction.
- Pass the supercritical CO2 through an extractor containing the plant matter itself.
- In Extraction Vessel, compounds are pulled from biomass into solution.
- Solvent (CO2) is boiled out of solution in Separator 1.
- Evaporated CO2 is condensed into liquid and stored in Accumulator.
- Pass the new solution through a separator to quickly and easily remove (and recycle!) the liquid CO2.
- After allotted run time, the system is depressurized by releasing CO2 through Separator 2 or 3. (Popular CO2 machines are often equipped with 3 separators： Waxes separation and Light oil separation in 1st separator. Light oil separation in 2nd separator. To trap lightest and volatile compounds in 3rd separator.)
In the video on the left is our entire process of extracting roses.
The turmeric essential oil in the picture is the extract we obtained in the experiment. The color is transparent and clear, and the smell is pure. Like other essential oils obtained by the CO2 extraction process, no special treatment is required. For example, the best-selling Ganoderma lucidum robe oil in China.
In the CO2 extraction process, CO2 is recycled in the machine, and the large CO2 extraction machine is also equipped with a CO2 recovery system to save production costs. Of course, some gas will be lost, about one-third of the weight of the extract.
Step 4: Molecular Distillation
The CO2 extraction process extracts essential oils or extracts from dried flowers (and other dried fragrant flowers such as hemp, rose, chrysanthemum, lavender, etc.), which contain waxes, chlorophyll, and other substances.
Distillation techniques are then required to separate CO2 essential oils.
How to make distillate: Distillation can be accomplished with short path distillation equipment or wiped film evaporation equipment. A distillation machine is typically used to improve the potency and color of the extract. Potency is typically improved by 10- 30% while the color of the oil is converted from an opaque dark amber – to a light amber – then to a clear light yellow.
When choosing your system, it is important to consider terpene retention during the extraction process. You can increase the terpene yield by properly prepping the material and also by adding a vapor condenser or cold trap to the system.
How does Short Path Distillation Work?
The short version of how short path distillation works, especially with regards to the refinement of crude cannabis or hemp oil is by separating out multiple desirable and undesirable compounds (THC, CBD, terpenes, etc.). The distillation of various compounds occurs at various boiling points and specific compounds can be collected in intervals.
As the sought-after cannabinoid reaches its boiling point it is vaporized, condensed, and collected in a vessel. The final product is beautifully pure distillate which is used in a wide variety of end-products, everything from vape pens, topicals, edibles, gel caps, sublingual, and more.
Typically, the distilled product has no taste or smell because it has had the terpenes separated out. These may then be added back in depending on the end product that you’re trying to produce.
CO2 Extraction Process Parameters
Extraction parameters will determine not only the type, quality, and yield of extract, but also the ease and cost of the extraction process.
The following sections will outline some of the overall trends determined by each of the four parameters.
Although temperature can be controlled at many stages in the process, the primary concern is the temperature of the extraction vessel. From the initial chosen temperature,
Increasing the extraction temperature:
- Decreases terpenoid concentration in the extract,
- Risks of possible denaturing of the product, and
- Increases wax/resin extraction (thereby increasing extract quantity).
Decreasing the extraction temperature:
- Increases the oil proportion of the extract, and
- Reduces the wax proportion of the extract.
The following are concerns regarding extraction pressure:
- From the initial chosen extraction pressure, increasing pressure increases wax/resin concentration in the extract
- Pressure over 5000 psi at 45 deg C causes chlorophyll extraction,
- Increasing pressure increases chlorophyll in the extract
- Increasing temperature increases chlorophyll in the extract
- Higher pressures are harder to maintain if CO2 supply is not continuous (cylinders instead of bulk)
The following are concerns regarding flow rate:
- Maintaining flow rate at higher pressures is more difficult due to a loss of CO2 supply (especially when using tanks and the cylinders are emptying).
- Increasing flow rate can cause dry ice accumulation, resulting in a higher chance of icing up lines unless additional heat is applied.
- Decreasing flow allows for the material to be in contact with the solvent for longer, increasing potential yield.
- Decreasing flow slows processing.
This is a processing time/solvent cost versus extract quantity amount issue. The correct ratio is the one that is most cost-effective.
For substances with greater polarity (such as flavonoids, saponins, alkaloids, etc.), a small amount of polar entrainer (or co-solvent, modifier, co-solvent) is often added to increase the CO2 polarity. The ability to dissolve sexual substances.
The addition of a small number of co-solvents (such as water, methanol, ethanol, acetone, ethyl acetate, etc.) can not only increase the density of the supercritical fluid, but more importantly, it can form a new strong intermolecular force with some solute molecules, Thereby improving the selectivity of the process.
CO2 Extraction Method of Natural Products
The supercritical CO2 fluid extraction process has obvious advantages in the extraction of active ingredients from natural plants, mainly involving alkaloids, anthraquinones, flavonoids, saponins, polysaccharides, volatile oils, pigments, terpenes and coumarin compounds, etc.
The supercritical CO2 extraction method can extract the effective components of hops α-acid, β-acid, and hop oil into a concentrated 5-10 times hop extract.
Hops are the main auxiliary material in beer production. It can impart unique bitterness and aroma to beer and is a preservative and aromatic in beer brewing. The traditional method of extracting hop extract is to use hexane, dichloromethane, and other organic solvents for extraction, the product quality is poor, and there are chemical solvent residues.
The use of supercritical CO2 extraction of hop extract not only greatly improves the utilization of effective ingredients, but also brewed beer has better foam and flavor.
The raffinate of supercritical CO2 extraction of hops is used as raw material to extract hop polyphenols.
When the extraction temperature is 40°C and the extraction pressure is greater than 25MPa, the content of polyphenols in the extract is significantly increased, and the content of polyphenols in the product obtained at a higher extraction temperature does not increase significantly. From the raffinate of supercritical fluid, extraction hops Extracting hop polyphenols can improve the value of hops’ comprehensive utilization.
Decaffeination of coffee
This is the first example of the industrialization of supercritical fluids (Maxwell, USA). The decaffeinated coffee produced presents a full aromatic profile (as a result of the low temperatures used and the absence of organic solvent). The extracted caffeine is, on the other side, sold to the pharmaceutical and food industries. There is therefore very little waste formed at the end of this process, making it economically and environmentally sustainable for now 30 years!
Dietary Supplement Edible Oil
The application of supercritical CO2 fluid extraction to vegetable oils is relatively extensive and mature.
People have done a lot of research on soybeans, peanuts, sunflower seeds, palm seeds, rice bran, wheat germ, corn germ, and other varieties.
The content is low, the color is light, and the refining process such as vacuum distillation and deodorization can be omitted. Compared with traditional methods, the residue after oil extraction still retains its original shape, which can be conveniently used to extract protein, blend into food, or use as feed.
Therefore, the supercritical CO2 fluid extraction method is widely used in the development of health oils (Dietary supplement edible oil) with high added value, such as rice bran oil, wheat germ oil, sea buckthorn oil, etc., and has achieved industrial application results.
Supplement edible oil CO2 extraction process:
Seabuckthorn Seed Oil, Grape Seed Oil, Ganoderma lucidum spore oil, Chrysanthemum oil, Fish oil, Kiwifruit Seed Oil, Onion Oil, Celery Seed Essential Oil, Konjac seed oil, Linseed oil, Camellia oil, Walnut Oil, Turmeric Oil, Wheat Germ Oil , Wolfberry Seed Oil.
Natural Food Pigment
Compared with the traditional organic reagent method, the supercritical CO2 fluid extraction process has no solvent residues and no pollution. It can avoid the thermal degradation of the extract at high temperatures, protect the activity of physiologically active substances, and can maintain Examples include the natural flavor of the extract.
Therefore, the supercritical CO2 fluid extraction technology has been applied to the extraction and purification of natural food pigments such as capsicum red pigment, lycopene, β-carotene, and gardenia yellow.
Natural food pigments carbon dioxide extraction process: Capsanthin, Lycopene
Natural Fragrances / Essential Oil
In the traditional extraction method of natural flavor, it is still an inevitable processing method that the flavor components are subjected to heat treatment. Such as water vapor distillation and solvent extraction heating may cause some heat-sensitive or chemically unstable components in natural spices to be destroyed, thus changing the unique aroma and flavor of natural spices.
The supercritical CO2 fluid extraction method can carry out the entire separation process at room temperature, and the CO2 is non-toxic and has no residual phenomenon, so it is particularly suitable for the separation and purification of unstable natural products and physiologically active substances, which is suitable for production closer to natural fragrance.
The trend of spice processing products. The supercritical CO2 fluid extraction method has attracted much attention because of the possibility of preparing almost perfect “natural” fragrances. It has become one of the most effective technological methods to obtain high-quality essential oil products.
Essential oil CO2 extraction process:
Garlic Oil, Ginger Essential Oil, Rose essential oil, Pepper oil, Nutmeg Oil, Tobacco Leaves Essence Oil, Lavender essential oil, Rosemary essential oil, etc.
Supercritical CO2 fluid extraction is an ideal separation method in natural medicine extraction.
Among the spectrum of the extracts obtained from plants, diterpenes (antioxidants), triterpenes (phytosterols), or even the tetraterpenes (carotenes) which may be of interest to the pharmaceutical sector, can be easily extracted.
Almost all the effective ingredients of natural medicines can be retained, mainly including flavonoids, glycogen compounds, alkaloids, mushrooms, coumarins, cardioverters, volatile oils, and other chemical substances.
Herbal oil CO2 extraction process:
Peppermint Oil, Oleuropein, Astaxanthin, Frankincense oil, Egg Yolk Lecithin, Neem Oil, etc.
5 advantages of the CO2 extraction process of essential oils
There are innumerable advantages of CO2 extracted essential oils whereby they have gained huge popularity.
Some of them are listed below:
- 100% Pure & Natural: For the purpose of obtaining the purest form of CO2 grade essential oils, the extraction process is carried out at a lower temperature by using carbon dioxide which is not only nontoxic but odorless too.
- Free from Leftover Residues: There is no serious concern about leftover residues in CO2 grade essential oils since only supercritical carbon dioxide is utilized for their extraction process under ambient temperature.
- Therapeutic Properties: The extraction process of CO2 possesses the great ability to obtain the maximum level of therapeutic components from botanical materials like plants and herbs.
- Pleasurable Natural Aroma: CO2 grade essential oils are widely cherished for their natural fragrance which resembles the original plant material as they are extracted without solvent & heat.
- Free From Adulteration: The CO2 extraction method is the perfect choice for the preparation of 100% natural essential oils as they have not been extracted from any petroleum derivatives-based products like hexane or butane.
Differences between: Cold-pressed method, CO2 extraction method, Hydro-distillation method, and Solvent extraction method.
|Cold Pressed method||CO2 Extraction method||Hydro-Distillation method||Solvent extraction method|
|Utilized for the extraction of Carrier and Base Oils.||Utilized for the extraction of premium-quality Essential Oils.||Utilized for the extraction of Attars.||Utilized for the extraction of Absolutes.|
|Usually, oily nuts and fruits are taken for the extraction of Carrier & Base Oils.||The aromatic parts of the plants like Leaves, Flowers, Stems, etc. are used for the extraction of Essential Oils.||Floral parts, petals, and leaves are taken from the plants & herbs for the extraction of Attars.||Any desired part of the plant can be utilized for the extraction of Absolutes.|
|Without any involvement of carrier, only compression of botanical material works to obtain Carrier & Base Oil.||CO2 is used as a carrier to obtain the oil from the parts of the plant.||Water is used as a carrier for the purpose of extracting the oil content from the fragrant parts of plants.||Hexane, ethanol, methanol, or petroleum ether is used for the extraction of oil content from botanical materials.|
|The mechanical pressure and usual temperature are used to obtain Carrier or Base Oils.||For the extraction of Essential Oils, only high pressure is required. The CO2 extraction process occurs at a moderate temperature.||In order to obtain the final product, high heat is used to evaporate the water content from the mixture.||Only mild heat is used to enhance the evaporation rate of the solvent. Also, cooling may be required at last.|
Is the CO2 extraction PROCESS safe?
When done by trained professionals in properly equipped labs, CO2 is among the safest extraction techniques available. From an environmental and health perspective, it is less toxic than petroleum-based hydrocarbons such as butane or propane.
CO2 boasts another feature that also adds to its safety. Any residual CO2 which remains in the extract evaporates, so there is no residual solvent left in the product.
Is CO2 extraction better than other methods?
The relative safety and non-toxicity of CO2 extraction generally render it a more appealing option than other extraction methods. The versatility of the technology also offers an edge over other methods. Modification of the temperature and pressure allows different terpenes, and other compounds to be targeted, allowing the extraction process to be customized for different formulations. Most importantly, the nature of the CO2 extraction process itself tends to result in a superior product.
Benefits of Supercritical CO2 Extraction
By using supercritical CO2, the producer has total control over the procedure, and CO2 can be recycled, making this method more environmentally friendly compared to others. Further, the Federal Drug Administration (FDA) has labeled CO2 safe for industrial extractions. CO2 acts as a cleaning agent, so microbial bacteria, molds, and mildews are killed during the process. The yield using supercritical CO2 is higher than other extraction methods; however, the yield and quality of the product can easily be varied by adjusting the physical properties.
If there is residue on the extract, it will evaporate, as CO2 is a gas at room temperature. Extracts obtained from supercritical CO2 extraction are appealing to the food and beverage and medical industries because it is guaranteed there is no residual solvent present in the product. Because there is no residual solvent on the product, the extract will be purer than many solvent-based extraction methods. Additionally, the plant is not subjected to extreme temperatures, so it does not experience degradation as it does during other extraction methods.
How Does CO2 Extraction Process Work?
While terms like “supercritical” can sound pretty complex and hard to grasp, the CO2 extraction process is actually a pretty simple and straightforward process. There are two basic steps in the carbon dioxide extraction method.
Steps to CO2 Extraction
First, the ground plant solids (Our recommended particle size is 60-80 mesh) are placed in the extraction chamber.
Pressurize liquid CO2 to a supercritical state and into the chamber, where thanks to its properties, CO2 acts as a solvent and dissolves the oils while capturing the essential active compounds at the same time and separating compounds such as terpenes.
In the second step, the supercritical fluid is moved into a “separation vessel,” where heat and pressure encourage the active compounds to separate from the carbon dioxide, where it becomes an immiscible fluid thanks to temperature and pressure gradients. The final step includes the extraction of CO2 by letting it stabilize back to its gaseous state, this enables it to restabilize as gas and flow back into the CO2 tank, leaving behind amber-colored cannabis oil.
Bear in mind; that this is a rather oversimplified version of the extraction process as there are many more nuances involved.
What’s the difference between the subcritical and supercritical CO2 extraction methods?
CO2 extraction is available in two forms: supercritical CO2 extraction and subcritical CO2 extraction. They’re similar extraction methods with two key differences: temperature and pressure.
Supercritical CO2 extraction
CO2 reaches a supercritical temperature at slightly above room temperature, which means it can be converted to a liquid, allowing the safe extraction of volatile active compounds that may be degraded by heat. Supercritical fluid extraction (SFE) utilizes CO2 in this state where it exhibits both gas and liquid properties. In this supercritical phase, it moves through the plant material like a gas but dissolves trichomes like a liquid.
The compound-rich solvent is then delivered into a vessel that lowers the pressure and temperature, separating the active compounds and terpenes.
Subcritical CO2 extraction
Subcritical CO2 extraction involves a similar process but with a lower temperature and less pressure.
Supercritical CO2 extraction is the most common CO2 extraction technique used for cannabis because it offers a higher yield more rapidly.
Is CO2 extraction better than cold-pressed?
Cold-pressed oil is obtained through pressing and grinding fruit or seeds with the use of stainless steel presses.
The raw plant material is placed between horizontal plates which are drawn together by a rotating screw (the ‘expeller’), and the oil is squeezed out.
Despite the name, a certain amount of heat is produced during the process due to friction, averaging at about 40˚C. To be marketed as cold-pressed, the temperature must stay below a rather toasty 49˚C.
Just like if we were subjected to these temperatures, delicate ingredients can end up less than ‘fresh’ and many of their therapeutic properties are lost.
CO2 EXTRACTION VS COLD-PRESSED
CO2 extraction is best because oxygen-free environments and low temperatures are particularly important when extracting fragile oils like Rosehip.
By keeping temperatures low and extracting all the ‘active’ components, we’re able to preserve and protect the complete botanical, skin-loving properties of the Rosehip.
This process delivers twice the regenerative sterols and five times more of those carotenoids than your average Rosehip seed oil. It also means it lasts four times longer in your bathroom cabinet!
This includes the incredible natural color and smell. You only have to see how orange, concentrated and herbaceously-scented Rosehip BioRegenerate is to witness CO2 extracts at their best!
CO2 extraction also leaves absolutely no solvent residues, so the final oil is impeccably pure. The low temperature and lack of waste streams/emissions make it an extremely environmentally friendly process, too!