I. The following essay will set out the principle of ultrasonic extraction technology
Ultrasonic extraction technology is predicated on the utilisation of ultrasonic waves for extraction purposes. The propagation of ultrasonic waves within a medium gives rise to acoustic vibrations and the rupture of minute cavities, thereby inducing violent physical and chemical reactions. These reactions have the capacity to promote the accelerated dissolution and migration of the active constituents in herbs, thus enhancing the extraction efficiency. Specifically, the high-frequency mechanical oscillations generated by ultrasound in the liquid lead to a cavitation effect, i.e., tiny bubbles are formed in the liquid and rapidly close, generating transient high pressures, and this extreme stress overcomes the selectivity of the cell membranes and quickly destroys the cell walls, leading to a high mass transfer between the internal cells and the surrounding solvent.
II.The advantages of ultrasonic extraction technology
The following points demonstrate the technology's benefits:
1. Enhanced extraction efficiency: Ultrasound can accelerate the dissolution and migration of the active ingredients in herbs, thus improving the extraction efficiency. Research has indicated that the use of ultrasound-assisted extraction technology to extract the active ingredients of herbs is more efficient than traditional methods.
2.Furthermore, the extraction speed is accelerated due to the role of ultrasound, thereby shortening the production cycle.
3.The technology is also relatively straightforward to operate; the user simply places the herbs and extraction solvents into the ultrasonic extractor, and the ultrasound element completes the extraction process.
4. Environmental protection and energy saving: ultrasonic extraction does not require heating, thereby reducing energy consumption and avoiding the production of harmful substances that may be produced by traditional extraction methods.
5. Wide range of application: ultrasonic extraction technology is suitable for the extraction of active ingredients of a variety of Chinese herbs, such as flavonoids, alkaloids and so on.
Ⅲ.The application of ultrasonic extraction technology in the herbal medicine industry
Ultrasonic extraction technology is a widely employed method for the extraction of active ingredients from herbal medicines, encompassing the following categories, albeit not exclusively:
- Alkaloids: e.g. mandelicine from mandrake leaves, alkaloids from belladonna.
- Glycosides: e.g. lilacoside from Sophora japonica, aspalathin from Tianma.
- Flavonoids and polysaccharides: e.g. flavonoids from Ginkgo biloba, polysaccharides from Ganoderma lucidum.
- In the context of volatile oils and flavours, ultrasonic extraction has been demonstrated to be a method that can preserve the specific flavour of the extract and reduce the loss of volatile components.
In addition, ultrasonic extraction techniques have been used to extract oils, proteins and other components of herbs.
IV.The challenges and limitations of ultrasonic extraction technology
Notwithstanding the numerous advantages of ultrasonic extraction technology, there are still some challenges in its practical application:
-The expense of the necessary equipment is a key challenge, as the high initial cost of ultrasonic extraction equipment may limit its application in small enterprises.
-The industrialisation of ultrasonic extraction technology is still facing technical challenges, such as the attenuation and uniformity of ultrasound.
-Finally, the protection of thermosensitive components during the extraction process is a significant consideration, as ultrasonic extraction may still lead to oxidation in some instances, despite the low temperatures employed.
