How CBD is extracted: a guide to methods and why it matters for what you buy

When you buy a CBD oil, flowers or a resin, what you are holding is the result of an industrial or artisanal process that can make the difference between an outstanding product and a mediocre one. The extraction method determines the purity of the extract, the presence of terpenes, the absence of residues and, ultimately, the end user’s experience. Yet few brands clearly explain how they make their products.

In this guide we walk you through the main CBD extraction methods, the pros and cons of each, and how to use that information to make better buying decisions.

Why the extraction method matters

The hemp plant (Cannabis sativa L.) contains dozens of cannabinoids, terpenes, flavonoids, chlorophyll, waxes and lipids. The goal of extraction is to separate the compounds of interest —mainly cannabidiol (CBD) and the rest of the phytochemical profile— from everything that is not wanted in the final product.

A poor extraction method can leave toxic solvent residues, destroy volatile terpenes that enhance the effects of cannabidiol, carry over chlorophyll that adds bitterness, or fail to bring THC down to legal levels. On the other hand, a well-executed extraction preserves the plant’s full profile, guarantees the absence of contaminants and produces a stable extract that is consistent from batch to batch.

The chosen method also determines whether the final product is a full spectrum extract (with all the original cannabinoids and terpenes), broad spectrum (THC-free but with the rest of the profile) or an isolate (99% pure CBD). This distinction matters because some preliminary studies suggest that the combination of cannabinoids and terpenes may have a greater synergistic effect than isolated compounds, a phenomenon known as the entourage effect.

In short: the extraction method is not a minor technical detail. It is one of the factors that most shapes the quality of what you use.

Supercritical CO2 extraction

Supercritical carbon dioxide extraction is the gold standard in the high-end CBD industry. When CO2 is subjected simultaneously to pressures above 73.8 bar and temperatures above 31 °C, it reaches a state in which it behaves both as a liquid and as a gas: the so-called supercritical state. At this point, CO2 has an exceptional solvating power and can penetrate plant material very efficiently.

How the process works

The hemp biomass, previously dried and ground, is placed in an extraction chamber. Supercritical CO2 flows through the material and selectively dissolves the cannabinoids, terpenes and other compounds of interest. The pressure is then dropped sharply: the CO2 returns to a gaseous state and evaporates naturally, leaving only the concentrated extract. The gas can be recovered and reused, which makes the process very efficient from an environmental point of view.

Advantages

• It leaves no solvent residues in the final product.
• Pressure and temperature can be adjusted to selectively extract different fractions (cannabinoids, terpenes, waxes).
• It produces high-purity extracts with a well-preserved phytochemical profile.
• It scales industrially with batch-to-batch consistency.

Disadvantages

• It requires very expensive equipment and qualified technical staff.
• High pressures can damage some terpenes if the parameters are not set correctly.
• The production cost is passed on to the final price of the product.

When you see “supercritical CO2 extraction” on a label and the price reflects that quality, it is generally a good sign. The highest-quality CBD oils on the market are usually made with this technique.

Ethanol extraction

Ethanol —pharmaceutical-grade, high-purity ethyl alcohol— is one of the most widely used solvents in the phytochemical industry in general, and in cannabinoid extraction in particular. Its efficiency, moderate cost and well-known safety profile make it a very common choice among producers of all sizes.

How the process works

The hemp biomass is soaked in or washed with cold ethanol (sometimes at temperatures of -40 °C or lower, in what is known as cold extraction or cryo-extraction). The alcohol dissolves the plant’s cannabinoids and terpenes. The solvent is then removed through controlled evaporation, yielding an oleoresin that can undergo further refining.

Advantages

• High extraction efficiency: ethanol recovers virtually all the CBD present in the biomass.
• Scalable to large volumes with more affordable equipment than CO2.
• Cold extraction minimises the co-extraction of chlorophyll and waxes, improving the quality of the crude extract.
• It can yield full spectrum extracts with a good terpene profile when the process is well controlled.

Disadvantages

• Ethanol is flammable, which calls for strict safety protocols at the facilities.
• If the temperature is not properly controlled, it can pull in chlorophyll and pigments.
• Fully removing the residual solvent requires careful evaporation; a sloppy process can leave traces.

The CBD resins and broad spectrum extracts you will find on the European market are largely made through well-optimised ethanol extraction.

Olive oil extraction

Olive oil extraction is the oldest, most accessible and simplest method of all. It requires no specialised equipment or hazardous substances, and can be done at home with ordinary kitchen utensils. For that reason, it is the preferred method for artisanal preparations and for people who want to make their own hemp oils at home.

How the process works

First, the plant material (hemp flowers or leaves) undergoes decarboxylation: it is heated in an oven at around 110-120 °C for 60-90 minutes to convert CBDA (the inactive acidic form) into active CBD. The decarboxylated material is then mixed with extra virgin olive oil and heated in a double boiler for several hours (usually between 1 and 3 hours at 95-100 °C). The oil acts as a lipid solvent and extracts the fat-soluble cannabinoids and terpenes.

Advantages

• Completely natural, with no synthetic solvents or industrial equipment.
• No risk of toxic residues in the final product.
• Olive oil brings its own beneficial polyphenols and fatty acids.
• Ideal for home-made, small-scale preparations.

Disadvantages

• The extract cannot be concentrated: the CBD concentration in the final product is noticeably lower than with CO2 or ethanol.
• The product is perishable and must be kept cold and in the dark to prevent the oil from oxidising.
• It is not viable for industrial production or for obtaining standardised isolates or broad spectrum extracts.

This method has educational value and some interest for personal use, but commercial products of guaranteed quality are not made exclusively with oil extraction because of its limitations in concentration and stability.

Molecular distillation

Strictly speaking, molecular distillation is not a primary extraction method: it is a refining and purification technique applied to extracts already obtained with CO2 or ethanol. However, it is so decisive for the quality of the final product that it deserves its own section.

What it is and how it works

Molecular distillation (also called short-path distillation) separates the components of an extract based on their different boiling points under high-vacuum conditions. Working under vacuum significantly lowers the temperatures needed to evaporate each fraction, which makes it possible to separate the cannabinoids without degrading them.

The process involves several prior steps: winterisation (chilling the crude extract to precipitate waxes and lipids, which are filtered out cold), decarboxylation (if it has not been done before) and finally the molecular distillation itself. The result is a CBD distillate with concentrations that typically exceed 80-90% cannabidiol, with a clean and stable profile.

What it is used for

Molecular distillation is the essential step before obtaining CBD isolates (pure CBD >99%). It also makes it possible to separate terpene-rich fractions, which can later be added back to the extract to obtain broad spectrum products with a controlled aromatic profile. Some high-end full spectrum extracts go through partial distillation to remove residual THC and comply with European legal limits without destroying the rest of the phytochemical profile.

How to choose a product based on its extraction method

Knowing the extraction methods is useful, but what really matters in practice is turning that knowledge into a buying decision. Here is a simple guide:

Look for process traceability

A serious brand states the extraction method used on its product page or website. If that information is nowhere to be found, it is a red flag. Transparency in the production process is the first indicator of quality.

Insist on independent lab tests

Whatever extraction method is claimed, the only way to verify what a product contains is through chromatographic analysis carried out by an accredited third-party laboratory. These tests should confirm the CBD concentration, the absence of THC above the legal limit, and the absence of solvent residues, heavy metals and pesticides. At Maionais we publish our lab certificates openly so you can check for yourself before you buy.

CO2 for premium oils and extracts

If you are looking for a CBD oil with the best possible profile, prioritise those made with supercritical CO2. The price will be somewhat higher, but the purity, the absence of residues and the stability of the phytochemical profile justify it. Our CBD oils, available from €29, are made with this philosophy of verified quality.

Ethanol for good-value broad spectrum extracts

Well-executed ethanol extraction produces high-quality extracts at a more affordable price. It is a valid option as long as the producer shows that it properly removes the residual solvent and carries out rigorous analytical testing.

Pay attention to the spectrum type

The extraction method is directly linked to the product’s spectrum type:

• Full spectrum: preserves all the original cannabinoids and terpenes. Generally obtained with CO2 or low-temperature ethanol without excessive refining.
• Broad spectrum: THC-free but with the rest of the profile. Requires molecular distillation to selectively remove THC.
• Isolate: pure CBD >99%. The product of molecular distillation and even subsequent crystallisation. No terpenes or other cannabinoids.

For CBD flowers, the concept of “extraction” does not apply in the same way: the cannabinoid and terpene profile is determined by the strain, the growing conditions (indoor, greenhouse or outdoor) and the subsequent curing. In this case, what matters is certified origin, the absence of pesticides and proper storage of the product.

Frequently asked questions

Which CBD extraction method is best?

It depends on the end use. For everyday oils and extracts, supercritical CO2 extraction offers the best combination of purity, absence of residues and preservation of the phytochemical profile. For small-scale artisanal preparations, olive oil is a safe option, although less concentrated. The most important thing is not just the method claimed, but that the producer backs it up with verifiable lab tests.

Is CO2-extracted CBD safer than ethanol-extracted CBD?

Both methods, when carried out correctly, produce safe extracts with no toxic residues. CO2 has the advantage of not requiring active solvent removal, because the gas evaporates naturally. Ethanol, if completely removed during purification, does not leave residues either. The key lies in quality control and in the lab tests that certify it.

What is winterisation in CBD extraction?

Winterisation is a refining process applied after primary extraction. It consists of chilling the crude extract, mixed with ethanol, to very low temperatures (around -40 °C), which causes the plant’s waxes, lipids and fats to precipitate so they can be filtered out. The result is a cleaner extract.

Do CBD flowers also go through an extraction process?

Not in the strict sense of the term. CBD flowers and buds are sold just as they are harvested, without extracting or concentrating their compounds. The process that is applied is curing: controlled drying and maturing that stabilises the cannabinoids, preserves the terpenes and improves the product’s aroma. The quality of the flowers depends mainly on cultivation, strain and curing, not on extraction processes.

How do I know if a CBD product’s lab tests are reliable?

For a lab test to be reliable, it must meet several conditions: it must be carried out by an external, independent laboratory (not the manufacturer itself), accredited to recognised standards (ISO 17025 or equivalent), and it must include at least cannabinoid quantification, pesticide and heavy metal testing and —in the case of extracts— residual solvent testing. The results must be up to date and correspond to the specific product batch. At Maionais you can view all our certificates of analysis publicly and free of charge.

Sources and scientific references

• Brighenti, V. et al. (2017). “Development of a new extraction technique and HPLC method for the analysis of non-psychoactive cannabinoids in fibre-type Cannabis sativa L.” Journal of Pharmaceutical and Biomedical Analysis, 143, 228–236.
• Citti, C. et al. (2018). “A novel phytocannabinoid isolated from Cannabis sativa L. with an in vivo cannabimimetic activity higher than Δ9-tetrahydrocannabinol.” Natural Product Research, 33(20), 2968–2974.
• Wang, M. et al. (2016). “Decarboxylation Study of Acidic Cannabinoids: A Novel Approach Using Ultra-High-Performance Supercritical Fluid Chromatography/Photodiode Array.” Cannabis and Cannabinoid Research, 1(1), 262–271.
• Rovetto, L.J. & Aieta, N.V. (2017). “Supercritical carbon dioxide extraction of cannabinoids from Cannabis sativa L.” Journal of Supercritical Fluids, 129, 16–27.