Supercritical CO2 extraction technology has the advantages of energy saving, purity, rapidity, high efficiency, and simple operation because it combines rectification and liquid-liquid extraction, and plays an important role in the extraction and separation of effective components of traditional Chinese medicine.
1. Extraction of volatile oil
The volatile oil is sensitive to high heat, acid, and alkali, and is easily destroyed when extracted by traditional steam distillation, with low efficiency. At present, there is much research literature on the application of supercritical carbon dioxide to extract volatile oil, and the yield of the obtained product is high and the integrity of the components can be maintained. The researchers used organic solvent extraction (SE), steam distillation extraction (SDE), and supercritical carbon dioxide extraction (SFE-CO2) to extract celery seed oil. The results showed that the celery seed oil obtained by supercritical carbon dioxide extraction was better than the other two. The method has a high yield, strong aroma, good appearance, and no solvent residue. The optimal conditions for supercritical carbon dioxide extraction of celery seed essential oil were determined as follows: temperature 45 ℃, pressure 20 MPa, flow rate 15 L/h, extraction time 2 h. The researchers used supercritical carbon dioxide extraction and steam distillation to extract ginger oil from dried ginger, respectively. The yield of ginger oil by supercritical carbon dioxide extraction was about 3.8 times that of steam distillation, and 12.82% were detected by GC-MS. 6-gingerol (one of the main active ingredients) was not found in ginger oil obtained by steam distillation. Soh et al[5] used supercritical carbon dioxide to extract patchouli oil from patchouli (including stems). The activity is better than the traditional steam distillation method.
2. Extraction of alkaloids
Conventional alkaloid extraction methods mainly include water or acid water extraction, alcohol solvent or lipophilic solvent extraction, etc. A few volatile alkaloids can be extracted by steam distillation. The traditional solvent method is easy to cause solvent residues, and a large amount of acid or alkaline reagents are used in the extraction and separation process, and the effective components are lost more and are easily damaged. The supercritical carbon dioxide extraction technology can reduce the above shortcomings and provide a new method for the efficient extraction of alkaloids.
3. Extraction of flavonoids
The conventional extraction methods of flavonoids include water extraction, alkaline water or alkaline dilute alcohol extraction, organic solvent extraction, etc., but they have the advantages of a large amount of solvent, long time consumption, low extraction efficiency, high cost, and easy environmental pollution. shortcoming. The use of supercritical carbon dioxide to extract flavonoids can reduce the shortcomings of traditional extraction methods, shorten the operation time and improve the extraction efficiency.
4. Extraction of Quinones
Quinones are widely present in the plant kingdom. Free quinones are less polar and soluble in organic solvents such as chloroform and benzene, so organic solvent extraction can be used; quinones with free phenolic hydroxyl groups can be extracted with acid by alkali. Precipitation method; benzoquinone and naphthoquinone compounds with smaller molecular weight can be extracted by steam distillation. In recent years, the supercritical fluid extraction method has also been applied in the extraction of quinones, which can avoid the decomposition of quinones and improve extraction efficiency.
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