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What is the principle of supercritical extraction for plant pigments and essential oils?

Supercritical extraction is the use of gas in the presence of a liquid at high pressure and low temperature, with liquid and gas properties. A supercritical fluid is a state of gas and liquid that is neither gaseous nor liquid. It has a relatively high density and is similar to a liquid, and its viscosity is closer to that of a gas. Meet the requirements of the ideal extractant. The biggest advantage is that the temperature is low, the loss of easily decomposable substances at high temperatures can be avoided, and high boiling point and low volatile substances are extracted.

Supercritical gas generally uses carbon dioxide, has a low critical temperature, is an inactive gas, does not undergo chemical reaction during extraction, and is a non-combustible gas, tasteless, odorless, non-toxic, and very safe; cheap, purity High, easy to prepare, and can be recycled in production.

The specific application principle is that the extraction and separation are combined into one. When the saturated dissolved CO2 fluid enters the separator, the CO2 and the extract rapidly become two phases (gas-liquid separation) due to pressure drop or temperature change. Separate immediately, not only the extraction efficiency is high but also the energy consumption is low, which increases the production efficiency and reduces the cost; the pressure and temperature can be the parameters for adjusting the extraction process, and the pressure is fixed by changing the temperature and pressure to achieve the purpose of extraction. Changing the temperature also separates the material; conversely, the temperature is fixed, and the extract is separated by reducing the pressure, so the process is simple and easy to grasp, and the extraction speed is fast.

Supercritical technology is an emerging separation technology. The overall technical cost is high, the overall pressure requirements are high, and the equipment purchase cost is huge. It is generally used in high value-added fields such as food, cosmetics, and medicine. But its advantages are also particularly obvious. In recent years, there have been more and more applications in industry.
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