Ultrasonic extraction uses multi-stage effects such as strong cavitation effects, mechanical vibration, disturbance effects, high acceleration, emulsification, diffusion, crushing and agitation caused by ultrasonic radiation pressure, increasing the frequency and speed of molecular motion and increasing solvent wear. Through-force, thereby accelerating the entry of the target component into the solvent and promoting the extraction 1. Principle Ultrasonic is a kind of elastic mechanical vibration wave, which is essentially different from electromagnetic waves. Because electromagnetic waves propagate in a vacuum, ultrasonic waves must propagate through the medium, forming a whole process of expansion and compression as it passes through the medium. In the liquid, the expansion process creates a negative pressure. If ultrasound
extraction utilizes the strong cavitation response effect, mechanical
vibration, disturbance effect, high acceleration, emulsification,
diffusion, smashing and stirring effect produced by the pressure of
ultrasonic radiation to increase the frequency and speed of material
molecular movement, increase the penetrating force of solvent, thus
accelerating the entry of target components into solvents and
accelerating extraction. It's going on.
Principle of Equipment
Ultrasound is an elastic mechanical vibration wave, which is essentially different from electromagnetic wave. Because the electromagnetic wave propagates in the vacuum, while the ultrasonic wave propagates in the medium, when it passes through the medium, it forms the whole process of expansion and compression. In liquid, the expansion process forms negative pressure. If the ultrasonic energy is strong enough, the expansion process will generate bubbles in the liquid or tear the liquid into very small holes. The instantaneous closure of these holes produces instantaneous pressure, which is called cavitation. The whole process is completed in a short time. The cavitation is used to refine the material and make the emulsion, which accelerates the composition of the target into the solvent and improves the extraction rate. In addition to cavitation, many secondary effects of ultrasound are also conducive to the transfer and extraction of target components. The above effect of ultrasound is very effective in extracting target components from different types of samples. The high temperature and high pressure produced on the interface between organic solvent and solid matrix and the oxidation energy of free radicals produced by ultrasonic decomposition provide high extraction energy.
Compared with conventional extraction technology, ultrasonic extraction has advantages of high speed, low cost and high efficiency.
Compared with water boiling and alcohol precipitation, ultrasonic extraction has the following characteristics:
1. No need for high temperature
2. Atmospheric pressure extraction, good safety, easy operation, easy maintenance
3. High extraction efficiency
4. It has wide applicability. Most of the components of traditional Chinese medicines can be extracted by ultrasound.
5. Ultrasound extraction has little effect on the properties of solvents and target extracts.
6. Reducing Energy Consumption
7. The processing capacity of medicinal materials is large, multiplied or multiplied, and the impurities are small. The effective components are easy to be separated and purified.
8. The cost of extraction process is low and the comprehensive economic benefit is remarkable.
1. Oil extraction
Ultrasound enhanced oil extraction can greatly improve the extraction efficiency, improve the quality of oil, save raw materials and increase the amount of oil extracted. Ultrasound field can not only enhance the extraction process of substances by conventional fluids, but also enhance the extraction process of substances under supercritical conditions. The wheat germ oil was extracted from malt germ by supercritical fluid extraction (SFE) enhanced by ultrasound. The extraction rate of wheat germ oil increased after SFE with ultrasonic field, and the degradation of wheat germ oil was not caused.
2. Protein extraction
Ultrasound has a good effect in extracting protein. Ultrasound can not only crush the aforementioned material embryo in water, but also liquefy the protein, and extract the heat-unstable protein components. Ultrasound treatment can improve the extraction rate of protein, and it can also increase the separation temperature of the paste and reduce the viscosity of the paste, which can be used to produce high protein soymilk products directly. Soybean paste with different concentration, heat-treated soybean paste before grinding and soybean dregs separated from soybean paste were treated by ultrasonic wave. Compared with untreated soybean paste, the protein content of soybean milk treated by ultrasound increased.
3. Extraction of Polysaccharides
Compared with the traditional ultrasonic polysaccharide extraction process, the ultrasonic enhanced extraction process has the advantages of simple operation, high extraction rate, no material loss and no side effects. The extraction rate of Polysaccharides from Flammulina velutipes fruiting body can be increased by ultrasonic wave, and the extraction rate of Polysaccharides from Tremella fuciformis by ultrasonic hot water is higher than that by enzymatic method, and the extraction time is greatly shortened.
4. Extraction of Natural Flavors
Ultrasound has a great influence on the extraction rate. Supercritical fluid is enhanced by ultrasound, and capsaicin extraction efficiency in capsicum is obvious. The results of ultrasonic extraction of Valeriana officinalis flavor were compared with those of non-ultrasonic extraction. The absorbance of the filtrate with ultrasonic wave was higher than that of the filtrate without ultrasonic wave.
5. Food analysis
Ultrasound extraction is also used in the pretreatment of food samples.