The history of the development of subcritical fluid extraction technology
Subcritical fluid extraction uses subcritical fluid or a mixed solution of subcritical fluid as the solvent, and the solute passes through the system one after another It is a new technology for extracting target components from natural products through processes such as leaching, evaporation and desolvation, compression, and condensation recovery. When LPG, propane, butane, R600a, DME, R134a and sulfur hexafluoride exist in a subcritical fluid state, the diffusion performance of molecules is enhanced and the mass transfer speed is accelerated, which affects weakly polar and non-polar substances in natural products. The permeability and solubility are significantly improved. Extraction in a subcritical environment does not destroy heat-sensitive components and the target substance is intact. It is regarded as a transformative technology that is green and environmentally friendly and has broad prospects.
In 1939, Henry Rosenthal of the United States pioneered the use of compressed and liquefied low-grade gaseous alkanes for oil leaching (Patent No.: US2152664). Under pressure, the solvent leached grease in liquid form, mixing oil and wet oil. The solvent contained in the meal evaporates naturally under reduced pressure. The entire processing process is carried out at low temperature, the components in the oil are not oxidized, the protein in the meal is not denatured, and the production cost is low. There are also reports on subcritical fluid extraction methods in China. The invention patent (ZL 01108701.3) published on August 2, 2001 provides a method for extracting pyrethroids from subcritical liquefied petroleum gas; the invention patent (200610081101.1) published on November 28, 2007 provides a method for extracting pyrethroids from subcritical liquefied petroleum gas. A method for extracting natural pyrethrins from subcritical dimethyl ether fluid; the invention patent (200610104744.3) disclosed on April 16, 2008 provides a subcritical fluid extraction solvent and extraction method. Its main feature is to use liquid sulfur hexafluoride as the extraction solvent. .
The above-mentioned subcritical extraction-related methods are all limited to a specific subcritical fluid. The extraction objects mainly target weakly polar and fat-soluble components, and do not involve medium-polar and highly-polar target components. .
Research and development of subcritical extraction equipment for active ingredients of natural products
Extraction is an important step in the deep processing of natural products, and it is completed through extraction equipment. Extraction equipment has a great impact on the quality, yield and production efficiency of the extract. Modern natural product extraction equipment shows the following development characteristics:
A. Fast extraction speed, high efficiency, sufficient extraction of active ingredients, reducing waste of material resources;
B. Low solvent consumption , small liquid extraction coefficient, high leachate concentration, saving solvents and saving production costs in subsequent processes;
C. The extraction temperature should not be too high, especially for the extraction of heat-sensitive materials, to reduce damage to the active ingredients. ;
D. Good adaptability, suitable for the extraction of different materials;
E. Good production continuity, should be suitable for modern large-scale continuous production;
F. Energy saving, safe and reliable; simple structure and easy operation.
In addition, with the acceleration of the modernization of the deep processing industry of traditional Chinese medicine, plant extracts, and agricultural products, the extraction process technology relies more on automated control. The main reasons are:
A. Artificial control often causes fluctuations in process parameters. Fluctuations in process parameters will seriously affect product quality and output. Large-scale production should exclude artificial changes in indicators;
B. Large-scale production, artificial The adjustment is powerless, and electric or mechanical force should be used to complete large-scale movements;
C. The stability of large-scale production is paramount, and only through automatic control can stable production be achieved.
Automated production abroad has become very popular. Domestic automation components and software facilities can also meet the industrial production of extraction. Automatic measurement, automatic monitoring, automatic display, and automatic alarm have been selected by different manufacturers. It is foreseeable that the automation process of extraction technology will develop rapidly in China.
Subcritical fluid extraction is a new technology born after supercritical fluid extraction technology. It mainly solves the shortcomings of supercritical extraction equipment such as small volume, high cost, high energy consumption, and unsuitability for large-scale industrial production.
Although this technology has long been reported in laboratories in the United States, Japan and other countries, its successful application in industrial production was achieved by researchers in my country represented by Qi Kun. In the 1990s, "solvent leaching technology" was successfully transformed and applied in my country, and low-temperature soy protein powder was developed. Subsequently, No. 4 solvent extraction technology also achieved success in natural product extraction, and has built more than 20 lines for more than 10 domestic companies. The production line provides key equipment for the development of my country's precious oils, marigold lutein and capsicum red pigments. This technology is at the leading level in the world.
There are also reports on other individual subcritical extraction devices in China. , the utility model (ZL200620135969.0) disclosed on October 11, 2006 provides a device suitable for the extraction of polar and non-polar intermediates with a variety of solvents. By changing the extraction solvent and the action procedures of the valves, pipes, and equipment in the system , meet the requirements of different solvents for extraction temperature, pressure, time and flow direction, and complete the extraction of active ingredients in animal and plant raw materials. Although this device takes into account the extraction process requirements of non-polar and polar active ingredients, the process route is complicated. The equipment manufacturing cost is high.
The above-mentioned subcritical fluid extraction related devices have different structures due to the large differences in the properties of the extraction agents used. However, they generally have complex structures, high manufacturing costs, and are limited to certain types. Defects of a subcritical fluid