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Basic knowledge of supercritical CO2 extraction of vegetable oils

Supercritical CO2 extraction technology

Supercritical fluids

In supercritical fluids, CO2 is the most commonly used organic extractant because of its low critical pressure (7.38 MPa) and critical temperature (31.3 ℃), and it is easier to reach the supercritical state.

Advantages and features

Using supercritical CO2 as a solvent to extract vegetable oils, compared with traditional oil extraction technology, has the following advantages and characteristics:

  • CO2 is a non-combustible, non-toxic, resource-rich, easy-to-obtain, low-price, and environmentally friendly solvent, with production safety, and SC-CO2 has high diffusivity and strong dissolving ability.
  • Good selectivity. The dissolving ability of CO2 can be controlled by adjusting the temperature and pressure, thereby selectively extracting the target product, reducing impurities and highly enriching the effective ingredients of the target product, improving the product quality and appearance, and the process is simple, saving time and effort, three wastes Less pollution.
  • CO2 is a gas at room temperature and pressure, and the resulting product has no residual organic solvents.
  • Low-temperature operation protects the physiological activity of active substances, and can obtain products with stable active ingredients and higher quality. It can better protect protein components during the extraction process of vegetable oils and fats, which is conducive to the utilization of protein.
  • The grease obtained by SC-CO2 contains less phosphorus and has a light color. Degumming and decolorization can be omitted in the post-treatment; through process adjustment, most of the free fatty acids are removed, thereby eliminating the deacidification step, which not only simplifies the process, but also avoids nutrients Loss in the refining process.
  • Supercritical extraction technology can be combined with modern analytical techniques, such as thin layer chromatography, gas chromatography, liquid chromatography, gas-mass spectrometry, liquid-mass spectrometry, rectification, etc., so that it can be more efficient and rapid. The extracted vegetable oils are separated and analyzed.

Cognition of supercritical CO2 extraction technology

  • Over the years, in the process of applying supercritical CO2 extraction technology to extract vegetable oils and other high value-added lipids, more mature technical knowledge has been achieved:
  • The supercritical CO2 extraction conditions of vegetable oils containing a lot of polyunsaturated fatty acids are generally mild, with a pressure of 20-30 MPa and a temperature of 35-45 ℃;
  • Due to the low solubility of lipids in supercritical CO2, a higher CO2 flow rate and a longer extraction time must be used, and a suitable entrainer must be selected to increase the solubility;
  • The raw material crushing particle size is generally 40~60 mesh, and the moisture content is less than 5%;
  • Entrainers (such as 76% ethanol or 95% ethanol) are often used for extraction of substances rich in alkaloids to increase the extraction rate and shorten the extraction time.

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