CO2 extraction — the industry gold standard

TL;DR

• Supercritical CO2 (>31 °C, >74 bar) is both liquid and gas.
• Selective extraction via pressure & temperature variation.
• Pros: residue-free (CO2 evaporates), GRAS-certified, scalable.
• Cons: high capex (>CHF 200 000), possible terpene loss.

Why CO2 dominates the CBD market

CO2 is classified as food additive (E290) — no residue problem in the final product. Rovetto 2017 showed that supercritical conditions selectively extract cannabinoids and light terpenes.

Most large Swiss CBD brands (Alpinols, Cibdol, Ellexo) use CO2 for pharmaceutical reproducibility and Novel Food compliance.

Subcritical versus supercritical CO2 extraction

CO2 extraction can be fundamentally divided into two processes: subcritical and supercritical extraction. In the subcritical range, the system operates at lower temperatures and lower pressure, whereby the carbon dioxide remains in a liquid state. This gentle process is outstandingly suited to preserving the sensitive and highly volatile terpenes of the cannabis plant. However, the yield in this process is significantly lower, and the extraction time is considerably longer, which is why on an industrial scale, the process is usually only used as the first step of a multi-stage extraction.

In contrast, supercritical extraction uses higher temperatures and pressures at which the carbon dioxide exceeds the critical point. In this state, the gas simultaneously assumes properties of both liquids and gases. It penetrates deep into the plant material and dissolves cannabinoids highly efficiently. Through the precise control of pressure and temperature, operators can selectively manipulate the density of the solvent. This enables selective extraction, where specific groups of substances are targeted for isolation or undesired accompanying substances such as chlorophyll are left behind in the plant material from the very beginning.

• Subcritical extraction preserves temperature-sensitive terpenes through lower operating temperatures.
• Supercritical extraction offers maximum efficiency and shorter process times on an industrial scale.
• Pressure and temperature control allows for the targeted fractionation of individual constituents.
• Fractionated separation separates undesired plant waxes already during the extraction process.

Swiss quality standards and regulatory framework

In Switzerland, cannabis products are subject to strict legal requirements. For an extract to be marketable without narcotics control, the total THC content must strictly be below one percent. CO2 extraction offers Swiss manufacturers a decisive advantage here: since the carbon dioxide used escapes completely in gaseous form after depressurisation, no solvent residues remain in the end product. This significantly facilitates the proof of compliance to the cantonal enforcement authorities and the Federal Food Safety and Veterinary Office (BLV), as potential contamination by toxic solvents such as hexane or benzene is inherently ruled out by the system.

Since the amendment of the law in August 2022, medical cannabis in Switzerland can be prescribed directly by a doctor without an exceptional licence from the Federal Office of Public Health (BAG). For the manufacture of magistral formulations in pharmacies, the strictest quality requirements apply in accordance with the Pharmacopoea Helvetica. CO2 extraction has established itself as the standard in this pharmaceutical environment. The processes can be precisely validated and reproduced, which is essential for the standardisation of active ingredient concentrations. Furthermore, CO2 systems easily meet the strict Good Manufacturing Practice (GMP) requirements monitored by the Swiss agency for therapeutic products, Swissmedic.

• Reliable compliance with the legal Swiss THC limit of less than one percent for industrial hemp extracts.
• Residue-free production without the use of flammable or toxic solvents such as butane.
• Facilitated GMP certification for Swiss medical cannabis manufacturers in accordance with Swissmedic guidelines.
• Compliance with the strict guidelines of the Federal Food Safety and Veterinary Office (BLV).

Post-processing: From crude extract to premium product

The crude extract obtained immediately after CO2 extraction, also referred to as crude oil, is a viscous, dark mass. In addition to the desired cannabinoids and terpenes, this extract contains significant amounts of plant waxes, lipids, and chlorophyll. These co-extracted substances not only impair the taste and texture of the final product but can also reduce the stability of the oil. To remove these undesirable substances, extraction is followed by what is known as winterisation. In this process, the extract is dissolved in alcohol, cooled down significantly, and then filtered to separate the precipitated fats.

After purification, decarboxylation typically takes place. In the plant, cannabinoids exist primarily as acids, such as cannabidiolic acid or tetrahydrocannabinolic acid. Through controlled heating, a carbon dioxide molecule is split off, converting the active ingredients into their neutral, biologically active form. For high-purity products, the oil can then be further purified using vacuum distillation. This multi-stage refinement process ensures that Swiss consumers receive a standardised, clear, and taste-impeccable product that meets the high Swiss quality standards for consumer goods.

• Winterisation removes undesirable plant fats, lipids, and waxes for a clear final product.
• Decarboxylation activates the acidic cannabinoid precursors through targeted thermal treatment.
• Vacuum distillation concentrates the desired active ingredients and eliminates the final impurities.
• Enhancing the sensory quality and shelf life of the finished Swiss CBD oil.

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