Application of Ultrasound in Plant Extraction
Most of the medicinal ingredients of natural plants are intracellular products, and it is often necessary to break the cells during extraction. The existing mechanical or chemical breaking methods are sometimes difficult to achieve the ideal breaking effect. Ultrasound has been shown in the extraction of medicinal ingredients from terrestrial and marine plants. Out of obvious advantages.
Application of Ultrasound in Plant Extraction
Land plants: The application of ultrasound to biotechnology is a relatively new field of research. Studies have shown that ultrasound can activate the physiological and biochemical processes that certain enzymes and cells participate in. By changing the mass transmission mechanism of the reactants, the activity of enzymes can be improved and the metabolic process of cells can be accelerated. Ultrasound is used for the degradation of starch, which can significantly increase the solubility of starch in water while retaining obvious starch characteristics, but the enzyme activity is reduced after repeated ultrasonic treatments; Ultrasound is used to degrade chitin with high speed, low cost, and unchanged amino acid content ; Ultrasonic is used to extract fungal polysaccharides, such as cordyceps polysaccharide, lentinan, hericium polysaccharide, etc. Compared with traditional technology, ultrasonic enzymatic method has higher extraction rate, no material loss and side reactions during the reaction; in addition, ultrasonic is also used to degrade and extract a variety of grapes Glycan etc. Ganoderma lucidum polysaccharide is a kind of solid lignified fungal polysaccharide. The cell wall contains protein, chitin, cellulose and lignin. Its structure is compact. It is difficult to destroy the cell wall by general treatment methods, and it is difficult to extract the effective ingredients. The relative crystallinity was reduced from 23.4 to 0 by the action of 120 W ultrasonic wave, the specific surface area was increased by 85.5%, and the hydrolysis rate was significantly increased.
At present, some researches have been conducted on the use of ultrasound to extract medicinal active ingredients from land plants. The study on the extraction of anthraquinones from rhubarb by ultrasound shows that the total extraction rate can reach 95.25% after ultrasonic treatment for 10 minutes, while the total extraction rate is only 63.27% after decocting for 3 hours; the extraction rate can reach up to 20 minutes after ultrasonic extraction. 99.82%; paper chromatography and HPLC were used to analyze the products extracted by the two methods, which showed that ultrasonic treatment had no effect on the structure of the product. When studying the extraction of berberine from the rhizomes of Coptis, the ultrasonic treatment time, ultrasonic frequency and sulfuric acid concentration were investigated. The results show that the extraction rate of 20 kHz ultrasonic extraction for 30 min is the same as that of soaking for 24 h (8.12%). The study of the extracted product by nuclear magnetic resonance spectrometer shows that ultrasonic has no effect on the structure of berberine. The extraction of rutin from Sophora sophora by ultrasonic waves of different frequencies is compared with hot alkali extraction-acid precipitation. The ultrasonic method does not require heating, and only needs ultrasonic treatment with a frequency of 20 kHz for 30 min. The extraction rate can be increased by 47.6%. Ultrasound is used in the conventional alkaline soaking process for extracting berberine from Coptis chinensis. The extraction rate of berberine obtained by ultrasonic extraction for 30 minutes is more than 50% higher than that of alkaline soaking for 24 hours. The State Key Laboratory of Biochemical Engineering of the Institute of Chemical and Metallurgy of the Chinese Academy of Sciences undertook the national "Ninth Five-Year Plan" key project "Plant cell large-scale cultivation and production of artemisinin", using ultrasound to intensify the extraction of artemisinin with petroleum ether, which increased the extraction rate. The extraction time is greatly shortened, reducing solvent consumption, and the extraction product is tested by ultraviolet spectrophotometry and HPLC method, which shows that the impurity content is also less.
Marine algae: Dunaliella salina is rich in β-carotene. The first condition for extracting β-carotene from salt is to break the salt algae so that β-carotene can quickly and efficiently enter the extraction medium such as aqueous solution. Since the extracts are mostly intracellular substances, the cells generally need to be broken during the extraction process. Due to the chemical reaction occurring in the process, the use of chemical breaking methods can easily cause changes in the structure and properties of the extract and lose its activity, and it is difficult to effectively break the cells with mechanical breaking. Lu Deming et al. used ultrasonic waves of 30 kHz, 150 V, 46 kHz, 105 V, 4.64 kHz, 107 V, 48.2 kHz, and 109 V to break the salt algae under the condition of 20℃. The complete fragmentation rate of algae can reach 87%. Phycobilisomes are the light-harvesting pigments of certain algae. The spectral properties of phycobilisomes not only reflect their composition and structural characteristics, but also reflect the differences and evolutionary status of algae species. To study the spectral properties of phycobilisomes, a complete phycobilisome must be obtained. When the ideal algae body can not be obtained from the dracocystis using chemical and mechanical crushing methods, the complete phycobilisomes can be obtained by ultrasonic treatment with a frequency of 20-50 kHz and a voltage of 60 V for 10 minutes. The purpose of ultrasound is to break the cells of Asparagus solanacearum, exposing the inner capsule, and then vibrate the phycobilisome from the membrane of the inner capsule.
At present, the extraction of seaweed polysaccharides generally adopts boiling method and ethanol precipitation, and the recovery rate is very low. The National Key Laboratory of Biochemical Engineering, Institute of Chemical and Metallurgy, Chinese Academy of Sciences, is undertaking the Marine "863" Youth Fund Project "Ultrasonic leaching of seaweed polysaccharides and research on condensed phase extraction and separation methods". At the same time, it will study and solve the engineering amplification problem in the application of ultrasound, with a view to expanding the application of ultrasound in the extraction of marine active substances.
The application of ultrasound in the extraction of natural ingredients from land plants and marine algae plants has shown obvious advantages and has gradually attracted people's attention. Although some researches have been carried out at present, they are all carried out on a small scale in the laboratory, and simple process conditions experiments are carried out for some single specific extraction objects.
When ultrasound is used to extract natural plant components, the mechanism of action should be studied in depth in order to establish a set of more general models to provide a basis for the operating conditions of different extraction objects. At the same time, it pays attention to the research of related engineering problems and solves the problem of ultrasonic extraction engineering amplification.
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