Nownatural plant extractCommonly used extraction methods include solvent extraction, ultrasonic extraction, microwave extraction and enzymatic extraction, while supercritical fluid extraction and microwave-assisted extraction are widely used as new extraction techniques.
The solvent extraction method is to use a solvent to extract active ingredients from solid materials. The solvent used must have the characteristics of mutual solubility with the extracted solute. After the plant material is damaged, put it into a suitable container and participate in several times the amount of solvent. Optional Impregnation, percolation, decoction, reflux and continuous extraction are used for extraction. Bako's Salvia miltiorrhiza extract is extracted by solvent extraction method, and essential oils are extracted by solvent extraction method.
In the extraction process of the solvent extraction method, the concentration of the solvent, the ratio of material to liquid, the extraction temperature, and the extraction time will directly affect the extraction rate of the active ingredients. Cristina Juan et al. extracted ochratoxin A in rice by solvent extraction. , The content of OTA was determined by fluorescence detection method and liquid chromatography. The study showed that under the most suitable solid-liquid ratio, extraction temperature and extraction time, the highest OTA content in the extract was 4.17ng\/g. Monte D. Holt et al. The solvent extraction method was used to extract alkyl resorcinols from raw and cooked wheat seeds, and the experiment showed that the solvent extraction method could save the extraction time.
Ultrasonic extraction is to use the intense vibration and cavitation effect generated by ultrasonic waves to accelerate the release of substances in plant cells, disperse and dissolve them into the solvent, and at the same time can keep the structure and biological activity of the extracted substances unchanged. The principle of ultrasonic extraction is primarily a physical process. , is a relatively new extraction method that has gradually received attention in recent years. For most components, the ultrasonic extraction method can greatly shorten the extraction time, consume less solvent, and have a higher leaching rate than the conventional solvent extraction. Extract power.
In the process of ultrasonic extraction, the selection and concentration of solvent, ratio of solid to liquid, extraction temperature, and extraction time will directly affect the extraction rate. Ling Zhou et al. used ultrasonic extraction to extract 5 sp. Influence factors, the experimental study shows that the extraction rate increases with the increase of temperature, and increases with the increase of power. Hong Van Le et al. used ultrasonic to extract vitamin E and phenolic compounds in cherries, and first compared ultrasonic extraction. The difference in extraction time and extraction rate between the method and the enzyme extraction method. The experimental effect shows that the ultrasonic extraction method is 6 times shorter than the enzyme extraction method, and the extraction rate of the ultrasonic extraction method is 2-3 times that of the enzyme extraction. Zhong Aiguo et al. The method for extracting chlorophyll from fresh bamboo leaves is to quantitatively determine the content of the extracted chlorophyll with a spectrophotometer. The function shows that: compared with the commonly used organic solvent extraction method, the ultrasonic extraction method not only has high extraction rate, high speed, high power, but also It is extracted at room temperature, no heating is required, and energy is saved.
Supercritical fluid extraction (supercritical fluid extraction, SFE) is a relatively new type of extraction separation technology, and CO2 is generally used as the extractant. The principle of supercritical fluid extraction is to use the unique dissolving ability of supercritical fluid and substances in supercritical fluid. The solubility of the supercritical fluid is very sensitive to the change of pressure and temperature. The dissolved substances in the supercritical fluid are separated out by means of temperature increase and pressure reduction (or both) to achieve the purpose of separate purification. It has both rectification and extraction. It has the advantages of not easy inactivation of active ingredients, high product quality, and synchronous completion of the extraction and separation process.
In the mid-1980s, supercritical CO2 extraction technology was gradually applied to the extraction of plant active components, which was a relatively successful new technology for research and application. Ruey Chi Hsu et al. used CO2 and ethanol as solvents and used supercritical fluid extraction. Technology to extract the useful components of Ganoderma lucidum, the research effect shows that: supercritical fluid extraction method ensures the fluidity of Ganoderma lucidum extract and is not affected by temperature. Monica Waldeb.ck et al. used pressurized fluid extraction technology to extract squalene and squalene in olives. -Two components of tocopherol, the experimental effect shows: the solvent is ethanol, the extraction temperature is 190 degrees Celsius, and the extraction time is 10min, the extraction effect is the best. YI QI ANG GE and others use supercritical CO2 extraction technology to extract natural vitamins from wheat germ E. The influence of pre-extraction treatment and extraction process conditions on the yield was mainly studied. The experimental study showed that when the particle size is 30 meshes, the pressure is 4000-5000 psi, the extraction temperature is 40-50 degrees Celsius, and the CO2 fluid flow rate is 2.0 mL\/min. The extraction rate is the highest.
Microwave assisted extraction (MAE) is a new technology that uses microwave energy to improve extraction power. Microwave assisted extraction is a method of selectively extracting policy components from objects by using the characteristics of microwave heating. The parameters can be useful to heat the policy components to facilitate the extraction and separation of the policy components. The principle of the microwave-assisted extraction method to extract plants is that the plant samples absorb a lot of energy in the microwave field, while the surrounding solvent absorbs less, and then in the cells The internal thermal stress is generated, and the plant cells are divided due to the internal thermal stress, which makes the substances inside the cells directly contact with the relatively cold extraction solvent, which accelerates the transfer of the policy product from the inside of the cells to the extraction solvent, and then strengthens the extraction process. In principle, microwave-assisted extraction technology uses heat energy in the same way as soaking and filtration, but the extraction speed of plant extracts is much faster than that of traditional methods, which reduces the extraction time and avoids damage and degradation of valuable plant extracts. .
Now, the microwave-assisted extraction method has become a powerful tool for the extraction of natural plant active ingredients due to its fast extraction speed and better extract quality. However, the microwave-assisted extraction method is selective internal heating and requires the processed materials to have excellent water absorption. , in other words, the position of the product to be separated is easy to absorb water, otherwise it is difficult for the cells to absorb satisfactory microwaves to break themselves, and the product is difficult to release quickly. For the liquid extraction system, the solvent material is required to be polar, and non-polar solvents are resistant to microwaves. The effect is not sensitive. Ting Zhou et al. used microwave-assisted extraction to extract flavonoids and coumarin compounds from medicinal plants, and studied the effects of sample size, solid-liquid ratio, extraction temperature and time on the extraction rate through orthogonal experiments. The experimental study showed that the extraction rate was 98.7% under the optimal extraction process conditions. Li Haibin et al. used microwave-assisted extraction method to extract Mogrosides in dried monk fruit, and the extraction rate of flash microwave-assisted extraction method was 70.5%, which was higher than that of conventional water extraction method. 45 percent higher, and 50 percent shorter in time.
Microwave-ultrasound synergistic extraction
Microwave is a kind of non-ionizing electromagnetic radiation. The polar molecules of the radiated material are rapidly turned and oriented in the microwave electromagnetic field, and then tear and collide with each other to cause heat, which can ensure the rapid transmission and full use of energy, and has the advantages of High efficiency, energy saving, no industrial pollution and other benefits, but the penetration depth of microwave is limited (in the same order of magnitude as its wavelength), and its mass transfer function is not obvious in the enhanced extraction process. Ultrasonic is a high-frequency mechanical wave, which has a turbulent effect. However, the thermal effect generated by ultrasonic waves is not obvious and is limited to a very small scale around the cavitation bubble. Combining the two, the synergistic effect is conducive to the release of the wall-breaking components, etc., that is, A microwave-ultrasonic synergistic enhanced extraction technology can be used to obtain a high-efficiency, low-cost, pollution-free extraction method of bioactive substances. HeJT et al. used microwave-ultrasonic field synergy to extract water-soluble bioactive components from traditional Chinese medicine, and all achieved good effects. Luo Feng et al. used the microwave-ultrasonic synergistic extraction method to extract flavonoids from licorice. Ma Lihua et al. studied the effect of traditional distillation method and microwave-ultrasonic synergistic extraction method on the extraction rate of carotenoids in burdock, and determined the optimal extraction conditions through orthogonal experiments. Bai Hongjin et al. used anhydrous ethanol distilled water and anhydrous ethanol-distilled water (volume ratio of 1:1) as solvents, used microwave and ultrasonic to synergistically extract aloe vera, and used an edible oil oxidation stability tester to determine the effect of the extract on rapeseed oil. Antioxidative effects of lard, cottonseed oil and sunflower oil.