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Guide to the best CO2 extraction process of propolis

What is propolis

Propolis is resin (gum) collected by bees from plant spores or tree trunks, mixed with secretions from the upper glands and wax glands, and processed into a gel-like solid with an aromatic odor. It has a complex and unique chemical composition.

Modern scientific research has confirmed that the chemical composition of propolis can be basically classified into more than 20 types and more than 200 single substances. These include more than thirty aromatic esters, more than thirty flavonoid compounds, and more than thirty human essential trace elements such as selenium, calcium, zinc, iron, manganese, copper, strontium, and magnesium, and nearly twenty amino acids; more than ten Aromatic acids, beeswax, terpenes, fatty acids, and fatty acid esters; several types of sterols, alcohols, aldehydes, sugars, and ketones; and a variety of phenols, steroids, enzymes, vitamins, Alkenes, hydrocarbons, and other biologically active organic compounds.

Obviously, propolis is a natural “small medicine storehouse” with great potential.

Propolis has become a research hotspot for scientists from all over the world for its unique medical and health benefits. At present, the traditional process of extracting propolis collagen from alcohol, which is still in use at home and abroad, is widely used at present. This process is superior to the production method of water-extracted propolis solution.

Supercritical CO2 Extraction Technology of Propolis

The research of extracting the effective components of propolis by supercritical CO2 fluid technology is in the exploration and tackling stage. The use of supercritical CO2 fluid extraction to extract propolis flavonoids has many advantages: Light yellow color, no solvent residue, safety and health, fewer impurities, low heavy metal content, simple process, and so on.

However, using supercritical fluid extraction technology, the extract is a substance that is fat-soluble and hardly soluble in alcohol, has low flavonoid content, is gelatinous, and has anti-strain activity. Under the experimental conditions, the content of flavonoids in the extract is approximately 1/5 or less of the same raw material in ethanol extraction. Therefore, it can only be explained that the simple supercritical fluid extraction technology is suitable for the extraction of hue, flavor, and taste food or processed food materials.

Propolis CO2 Extraction Process Using Cosolvents

It is because of the extremely low solubility of flavonoids, lactones and polysaccharides, proteins, and tannins in supercritical fluid CO2 that they need to be dissolved under high pressure. Therefore, for solutes with very low solubility in supercritical fluids, it is necessary to add a small amount of cosolvent to the supercritical fluid system to change the phase behavior of the supercritical fluid system in order to achieve the purpose of greatly increasing its solubility. In view of the non-toxicity of ethanol, its solubility in SFE is large, and it is easy to use SFE for separation and other characteristics. Ethanol is selected as the preferred cosolvent. Although the cosolvent brings benefits to supercritical fluid extraction technology, the separation of the cosolvent mixed in the extractant and the recovery of the cosolvent present in the residue will increase some equipment and energy consumption.

Therefore, it is very important to study the influence of the amount of cosolvent and its concentration on the extraction effect. We will carry out research on the extraction technology of flavonoids in propolis with supercritical fluid extraction technology containing cosolvent in order to achieve the purpose of low extraction temperature, few organic solvents, short time, and high preservation of propolis flavonoids.

The CO2 Extraction method of Propolis

Supercritical CO2 has a density similar to that of a liquid, a large solubility, but a viscosity similar to that of a gas, and a large diffusion coefficient. The use of supercritical CO2 can extract effective components in plant tissues at a lower temperature and is particularly suitable for the extraction of heat-sensitive components. The supercritical CO2 extraction method has a short extraction process, low extraction temperature, and a closed system. The supercritical CO2 extraction process can improve the yield of fat-soluble components of ethanol leachables, which is an effective method for the extraction and research of the chemical constituents of Chinese herbal medicines.

Steps of CO2 Extraction Method

  • Take an appropriate amount of propolis raw material that has been de-doped and waxed in advance, crush and pass through a sieve.
  • Take the propolis powder and magnesium stearate, mix them in a tank mixer and transfer them to the extraction kettle.
  • Turn on the plunger pump and related equipment of the supercritical CO2 extraction device, pressurize and heat CO2, and make it extract the propolis in the extractor in a supercritical fluid state.

The effects of different extraction pressure, extraction temperature, ratio of raw materials to auxiliary materials, separation pressure, separation temperature, extraction time, and flow rate on the extraction rate were investigated during the experiment.

Factors Affecting Propolis CO2 Extraction Efficiency

Extraction time

At an extraction temperature of 55 ° C, an extraction pressure of 25 MPa, 70% ethanol as the entrainer, and a solid-liquid ratio of 7: 1 (w / v), the propolis was extracted for 2hr, 3hr, and 4hr, and the extracts were measured separately.

The flavonoid content of the extract reached a maximum when the extraction reached 3 h. As the extraction time continues to increase, the flavonoid content of the extract decreases. It may be that with the extension of the extraction time, the number of other substances extracted increases, while the flavonoids no longer increase, resulting in a decrease in the mass percentage of the extract.


At an extraction temperature of 55 ° C, an extraction pressure of 30 MPa, 95% ethanol as the entrainer, and a solid-liquid ratio of 5: 1 (w / v), the propolis was impregnated with the entrainer for different times and then extracted, and then The total flavonoid content of the extract was measured.

The flavonoid content of the extract is the highest without infiltration. The reason may be the infiltration of ethanol, and more of the non-flavonoid polar substances are dissolved. In the case of extraction, as the infiltration time is extended, the content of these substances gradually increases, which makes the total flavonoid content of the extract decrease.

Orthogonal experiment optimization

Through single factor experiments, it was determined that the supercritical CO2 extraction of used the cosolvent non-wetting method to extract propolis for 3hr.

Relevant literature shows that only when the temperature and pressure of supercritical extraction are above 45 ° C and 20 MPa, respectively, can flavonoids be extracted more; and the excessive temperature and pressure are contrary to the experimental goals. Therefore, the temperature and pressure range selected in the experiment were 45 ° C to 55 ° C and 20 to 30 MPa, respectively. The amount of entrainer is referenced in the literature. The solid-liquid ratio is 5: 1 to 7: l (w / v).

Perform orthogonal experiments on the extraction temperature, extraction pressure, entrainer type, and solid-liquid ratio of several main factors in the extraction conditions of propolis. The analysis shows that the range of A (extraction temperature) is the largest, followed by B (extraction pressure), C (entrainer type), and D (solid-liquid ratio). The major and minor factors determine the range of the range: A> B> C> D.

Therefore, based on the comprehensive test results and the economic benefits of the manufacturing company, the optimal conditions for the optimized supercritical extraction of propolis were determined as follows: the extraction temperature was 50 ° C, the extraction pressure was 25 MPa, the cosolvent was 95% ethanol, and the solid-liquid ratio was 6: 1. Propolis was extracted under the optimal conditions, and the flavonoid content of the obtained extract was 14.8%.

The CO2 extraction process of propolis

  • Extraction temperature:50 ° C,
  • Extraction pressure:25 MPa,
  • Cosolvent:95% ethanol,
  • Solid-liquid ratio:6: 1.
  • Propolis was extracted under the optimal conditions, and the flavonoid content of the obtained extract was 14.8%.