Methods for extracting plant extracts!

At present, the common methods for extracting plant extracts are solvent extraction, ultrasonic extraction, microwave extraction and enzyme extraction. Supercritical fluid extraction and microwave assisted extraction are widely used as new extraction technologies. Solvent extraction Solvent extraction refers to the extraction of effective components from solid materials by solvent. The solvent used must be mutually soluble with the extracted solute. After destroying the plant materials, put them into a suitable container, add several times of solvent, and extract them by soaking, percolating, boiling, reflux, continuous extraction and other methods. Salvia miltiorrhiza extract. The essential oil was extracted by solvent extraction. In the process of solvent extraction, solvent concentration, solid-liquid ratio, extraction temperature and extraction time will directly affect the extraction rate of effective components. Cristina Juan et al. extracted ochratoxin A from rice by solvent extraction, and determined the content of OTA by fluorescence detection and liquid chromatography. The results showed that the content of OTA in the extract was the highest, 4.17ng/g, under the most appropriate ratio of material to liquid, extraction temperature and extraction time. Monte D. Holt et al. selected solvent extraction method to extract alkyl resorcinol from raw and ripe wheat seeds. The experiment shows that solvent extraction can save extraction time. Ultrasonic extraction Ultrasonic extraction is to accelerate the release, dispersion and dissolution of substances in plant cells to solvent by using the strong vibration and cavitation effect of ultrasonic, which can keep the structure and biological activity of the extracted substances unchanged. The principle of ultrasonic extraction is mainly physical process, which is a relatively new extraction method that has been paid more and more attention in recent years. For most components, ultrasonic extraction can greatly shorten the extraction time, consume less solvent, and have higher extraction rate than conventional solvent extraction, so it has higher extraction power. In the ultrasonic extraction process, solvent selection and concentration, solid-liquid ratio, extraction temperature and extraction time will directly affect the extraction rate. Zhou Ling et al. used ultrasonic wave to extract Schisandra chinensis. First, the factors affecting the ultrasonic extraction rate were discussed. The experimental results showed that the extraction rate increased with the increase of temperature and power. Hongle et al. used ultrasonic wave to extract vitamin E and phenolic compounds from cherries. First, they compared the differences in extraction time and extraction rate between ultrasonic extraction and enzyme extraction. The experimental results showed that the ultrasonic extraction time was 6 times shorter than that of enzymatic extraction, and the extraction rate was 2~3 times higher than that of enzymatic extraction. The ultrasonic wave was used to extract chlorophyll from fresh bamboo leaves, and the content of extracted chlorophyll was quantitatively determined by spectrophotometer. The results showed that compared with the ordinary organic solvent extraction method, the ultrasonic extraction method not only had high extraction rate, high speed and power, but also was extraction at room temperature, without heating and energy saving. Supercritical fluid extraction (SFE) is a new extraction technology, usually using CO2 as extractant. The principle of supercritical fluid extraction is to separate the substances dissolved in the supercritical fluid by increasing the temperature and decreasing the pressure (or both), using the unique solubility of the supercritical fluid and the sensitivity of the solubility of substances in the supercritical fluid to changes in pressure and temperature, so as to achieve the purpose of separation and purification. It has two effects of distillation and extraction, and has the advantages of not easy deactivation of effective components, high product quality, synchronous completion of extraction and separation process, etc. It is considered as a green and environment-friendly high and new separation technology. Especially in the mid-1980s, supercritical CO2 extraction technology was gradually applied to the extraction and separation of plant active ingredients, which is a successful new technology. Xu Ruiqi et al. used CO2 and ethanol as solvents and selected supercritical fluid extraction technology to extract the useful components of Ganoderma lucidum. The results showed that supercritical fluid extraction ensured the fluidity of Ganoderma lucidum extract, and was not affected by temperature. Monica Waldeb.ck and others use pressurized fluid extraction technology

Qionge et al. selected supercritical CO2 extraction technology to extract natural vitamin E from wheat germ, and discussed the influence of pretreatment and extraction process conditions on the yield for the first time. The experimental discussion shows that the extraction rate is the highest when the particle size is 30 meshes, the pressure is 40005000 psi, the extraction temperature is 4050, and the flow rate of CO2 fluid is 2.0 mL/min. Microwave assisted extraction (MAE) is a new technology that uses microwave energy to improve energy extraction. Microwave assisted extraction (MAE) is a method to selectively extract the guessed principal components by using the characteristics of microwave heating. By adjusting the microwave parameters, the principal components can be heated to facilitate the extraction and separation of the principal components. The principle of microwave-assisted extraction of plants is that plant samples absorb a lot of energy in the microwave field, while the surrounding solvent absorbs less. Then, thermal stress is generated in cells, and plant cells are broken due to internal thermal stress, which makes the substances in cells directly contact with the relatively cold extraction solvent, thus accelerating the transfer of strategic products from cells to the extraction solvent, thus strengthening the extraction process. In principle, microwave-assisted extraction technology not only uses heat energy, but also uses soaking and filtering. However, the speed of extracting plant extracts is much faster than traditional methods, which can reduce the extraction time and prevent valuable plant extracts from being damaged and degraded. At present, microwave-assisted extraction has become a powerful tool for extracting effective components from natural plants because of its fast extraction speed and good extraction quality. However, microwave-assisted extraction is selective internal heating, and requires the treated materials to have excellent water absorption. In other words, the position of the product to be separated is pure water absorption, otherwise the cell will be difficult to absorb enough microwave to break itself, and the product will be difficult to release quickly. As for the liquid extraction system, it is required that the solvent substance is polar, while the non-polar solvent is insensitive to the microwave effect. Zhou Ti et al. selected the microwave assisted extraction method to extract flavonoids and coumarins from medicinal plants, and discussed the effects of sample amount, material to liquid ratio, extraction temperature and time on the extraction rate through orthogonal experiments. The experimental discussion showed that the extraction rate was 98.7% under the optimal extraction conditions. Li Haibin et al. used microwave-assisted extraction to extract mogroside from dried mangosteen. The results showed that the extraction rate of microwave-assisted extraction was 70.5%, which was 45% higher than that of conventional water extraction, and the time was 50% shorter. Microwave assisted ultrasonic extraction is a kind of non ionizing electromagnetic radiation. The polar molecules of the irradiated material quickly turn and orient in the microwave electromagnetic field, and then tear and collide with each other to generate heat. This can ensure the rapid transmission and full utilization of energy, and has the advantages of high efficiency, energy saving and no industrial pollution. However, the penetration depth of microwave is limited (in the same order of magnitude as its wavelength), so the mass transfer effect is not obvious in the enhanced extraction process. Ultrasonic wave is a kind of high-frequency mechanical wave, which has turbulence effect, disturbance effect, interface effect and energy accumulation effect. However, the thermal effect of ultrasound is not obvious, which is limited to a small range around the cavitation bubble. Combining the two, the synergistic effect is conducive to the release of wall breaking components, that is, through the microwave ultrasonic synergistic enhancement of extraction techniques, an efficient, cheap, pollution-free extraction method of bioactive substances is obtained. HeJT et al. used microwave ultrasonic field to extract water-soluble bioactive components from traditional Chinese medicine, and achieved good results. Luo Feng et al. Microwave ultrasonic synergistic extraction method was selected to extract flavonoids from licorice. Ma Lihua et al. discussed the influence of traditional distillation and microwave ultrasonic synergistic extraction on the extraction rate of carotenoids in burdock, and determined the best extraction conditions through orthogonal test. Baijin et al. used absolute ethanol distilled water and absolute ethanol distilled water (volume ratio: 11) as solvents, selected microwave and ultrasonic to extract aloe, and selected edible oil for oxidation stability test.

In the process of enzymatic extraction, the selection of enzyme, enzyme concentration, pH value, enzymolysis temperature and enzymolysis time will affect the extraction rate of plant extracts. E. BARZANA et al. selected the enzyme extraction method to extract carotenoids from marigold. First, the effects of material to liquid ratio, enzyme concentration, enzymolysis time and temperature on the extraction rate were discussed. The results showed that the optimum extraction conditions were as follows: the ratio of material to liquid was 14, the concentration of enzyme was 0.3%, the extraction time was 1.5 h, and the extraction temperature was 25. Zhang Xiaoqing et al. selected the enzymatic method to extract ginkgo flavonoids, and found out the optimal technological conditions such as enzyme concentration, pH value, enzymolysis temperature and time. Through orthogonal test. There are many ways to extract plants. According to the content of different plants and the needs of users, there are many kinds of extraction processes and production processes. We need to know the customer's needs and plant ingredients to choose the extraction method suitable for us.