Top 3 Key Processes of Thyme Oil CO2 Extraction Process

The yield of thyme essential oil extracted by supercritical CO2 extraction process can be as high as 4.22%, which is far greater than steam method.  How to get the best thyme oil co2 extraction process? 
  • CO2 extraction pressure Temperature Extraction time

Through a CO2 extraction experiment, we give the answer

What is Thyme

Thyme, also known as thyme, is a perennial deciduous subshrub in the Lamiaceae family. It is botanically named Thymus vulgaris which belongs to aromatic herbs of the mint family Lamiaceae. It grows and reaches up to the height to 15 to 30 cm in length.

Originally produced in southern Europe, it is mainly used for health care vegetables, tea making, making sachets, pillows, condiments, refining natural flavors, and raw materials for food industry.

Supercritical CO2 fluid extraction of thyme essential oil
CO2 extraction process of thyme essential oil

In the case of whooping cough, thyme is a panacea, and in terms of other medicinal benefits, it’s used for stomach aches, diarrhea, arthritis, and sore throat. Thyme oil can influence the brain’s limbic system and can strengthen the nerves, helping in memory and focus. As well as it is good for combating depression, and infectious diseases.

It is also a natural spice for bartending, and it can also be used as a seasoning for soups. The aromatic smell released can prevent colds and have certain effects on skin tinea, coughs, and other diseases.

In China, it is widely distributed in low hills and shady slopes in Liaoning, Shandong, Hebei, Shanxi, Shaanxi, and other provinces.

Thyme co2 essential oil

Thyme Co2 Extract Oil has a sweet and strong herbal smell that is reddish-brown in color. It has myriads of health benefits for eczema, and itchy, scaly patches on the skin. Cough, infections.

Composition of thyme CO2 Oil

The composition of the volatile compounds are, 0.26% alpha pinene, 0.31% beta myrcene, 11.7% p-cymene, 0.24% limonene, 0.57% 1,8 cineole, 4.1% gamma terpinene, 1.7% linalool, 0.72% borneol, 61.6% thymol, 4.0% carvacrol, 2.7% beta caryophyllene.


Thyme oil is useful in strengthening nerves, aiding memory & concentration as well as helping with feelings of exhaustion & combating depression. It also helps in fortifying the lungs as well as helps with ailments like coughs, colds, asthma, sinusitis, laryngitis, catarrh, sore throats, whooping cough, and tonsillitis.


Thyme oil is beneficial for boosting the immune system as well as helps in fighting colds, flu, infectious diseases & chills. Further, as a urinary antiseptic, it is helpful for cystitis and arthritis. The warming effect of the oil also helps in cases of poor circulation, arthritis, gout, rheumatism, muscular aches & pains, sports injuries & sprains. It is also helpful for cellulite, obesity, anorexia, and edema as well as in cases of scanty periods, to speed up birth and leucorrhoea.

The extraction method of thyme oil

Usually, thyme essential oil is obtained by steam distillation and processing through oil-water separation. The yield of thyme essential oil obtained by steam distillation is too low and the cost is too high, thus restricting its production and use.

We use Gansu thyme as raw material and use supercritical CO2 extraction process (SFE-CO2) to extract thyme essential oil. The CO2 extraction process conditions were studied, and the best experimental conditions were screened to obtain essential oils with higher yields.

The CO2 extraction method of thyme oil

  • Accurately weigh 300g of the crushed (20 mesh) thyme raw material, put it into the extraction tank, use 95% ethanol as a co-solvent, and add 3% of the volume of the extraction tank (ethanol is an extremely strong nucleophilic addition property. Sexual substances can increase the polarity of the solvent CO2, and at the same time increase the polarity of the oil to be extracted, resulting in an increase in the separation factor of the entire system, thereby increasing the extraction rate).
  • Then the CO2 in the supercritical state was introduced, and the flow rate was 25L/min. At different temperatures, the extraction pressure and extraction time were changed, and the thyme was continuously extracted, and the extracts entered the separation tank for separation.
  • The pressure of the first separation and fractionation column is set to 9MPa, and the separation temperature is set to 50 ℃;
  • The separation pressure of the second separation and desorption tank is set to 4.5~5MPa, and the separation temperature is set to 50°C.
  • The liquid collected from the two separation kettles is then refined to obtain a pure reddish essential oil.
  • The CO2 is recycled after gasification, and the extract is released from the bottom of the separation tank. Weigh and calculate the yield.

Get the most efficient CO2 extraction method of thyme oil

CO2 extraction pressure

As the extraction pressure increases, the CO2 density increases, and the solubility of the solute increases, which is conducive to extraction. On the other hand, the diffusion coefficient of the solute will decrease, which is not conducive to extraction. Usually, the former plays a leading role.

The extraction time is 4h, the extraction temperature is 40 ℃, and the CO2 flow rate is 25L/min. At different temperatures, as the extraction pressure increases, the extraction yield will increase, but after the pressure rises to a certain level, the extraction yields The increasing trend of the rate began to slow down, when it reached 25MPa, the yield basically no longer increased, at this time the extraction yield was 4.22%.

Considering comprehensively, it is more appropriate to select the extraction pressure of 25 MPa.

CO2 extraction temperature

Under the same extraction pressure, the temperature is high, and the basic yield is also high. When the temperature is 40 ℃, the extraction yield is the highest.

If the temperature is too high, the yield will decrease instead.

This is because the temperature rise increases the diffusion coefficient of the substance, and the mass transfer rate of the fluid is accelerated, which is conducive to extraction; on the other hand, the temperature rise will cause the density of the fluid to decrease, thereby reducing the ability to dissolve organic matter, and the aromatic components are cooled by the separation kettle. If the effect is not sufficient, it will cause volatilization loss and oxidation, and increase the decomposition loss, which is not conducive to extraction.

Considering comprehensively, it is more appropriate to select the extraction temperature of 40 ℃.

Extraction time

When the extraction pressure is 25MPa, the extraction temperature is 40 ℃, and the CO2 flow rate is 25L/min, when the extraction starts, with the extension of the extraction time, the extraction yield shows a rapid increase trend. After 3h, the increase in yield tends to be small, and after 4h, the extraction yield is basically not Furthermore, from the perspective of energy saving (water and electricity), the relatively moderate extraction time is: 3~4h.

CO2 Extraction VS Steam Distillation

Steam Distillation

100g of thyme crushed sample, cold immersed in 25% NaCl solution for 24 h, and then distilled in a vacuum distiller for 3 to 4 h. Collect the distillate. After the salt is saturated, it is extracted 3 times with ether. The extract is concentrated and then used with anhydrous Na2 SO4 was dried to obtain 1.5903g of light red, transparent, aromatic essential oil, with a yield of 1.59%.


Process parameters: CO2 extraction pressure: 25MPa; temperature: 40 ℃; time: 4h; flow rate: 25L/min. The oil yield of essential oil extracted by supercritical CO2 is as high as 4.22%.


From the above results, the yield of thyme essential oil extracted by supercritical CO2 fluid can be as high as 4.22%, which is far greater than the yield of steam extraction.

Thyme oil CO2 extraction process

  • CO2 extraction equipment: L-01 CO2 extractor
  • CO2 extraction pressure: 250 bar;
  • Temperature: 40 ℃;
  • Extraction time: 120 min;
  • CO2 flow rate: 25L/min.
  • Oil yield: 4.22%.