Conventional And Ultrasonically Assisted Extraction Of Isoflavones From Pueraria Lobata Wild

The state-of-art review in isoflavone extraction and ultrasonically assisted extraction were given. The research of promotion in extraction yield and rate by ultrasonic was discussed.The influences of solvent, temperature, granularity and time to extraction were researched. The isoflavones were analyzed by spectra-UV. And the effect of the factors to extraction is solvent > temperature>granularity> time.Ultrasonically assisted extraction was investigated. The influence of ultrasonic intensity to different solvents (alcohol solution, water and so on) extraction was mainly studied in constant temperature and no temperature adjustment. And the influence of height/diameter ratio of the extractors on the extraction rate and extraction yield of total-isoflavones was investigated under the given ultrasonic power and solvent cubage. Under the condition, of constant temperature, the rate of ultrasonically assisted extraction were better than the stirring extraction after the ultrasonic intensity reached a certain amount, and the results show that the application of ultrasonic to extraction can reduce extraction time and increase isoflavone yield, and that the extraction rate increases obviously with ultrasonic power. The results also show that the height/diameter ratio affects the extraction yield for the given ultrasonic power and solvent cubage. The optimal height/diameter ratio for the cylindrical extractors is about 0.58, which is helpful to the design of ultrasonically assisted extractor.A model for ultrasonically assisted extraction was proposed. Based on the experimental phenomena, the reason of promotion in extraction rate by ultrasonically assisted extraction was regarded as: the cutting of ultrasonic would crash the original larger particles into very smaller particles, thus increasing the surface. In a limited time, almost all of the original pueraria lobata particles were crashed. According to the principle of force balance to the pueraria lobata particles, the relation of r*(the minimum size that a certain intensity of ultrasound could crash the particles to) withthe intensity of ultrasound was proposed. The final equation of the model is:Where Yt and Y were the yield of isoflavones in the leaching time of t and respectively, kD is constants that depend on extracting solvent and extracted materials. The model can correlate the ultrasonically assisted experimental data (alcohol solution and water) well. The average relative error is 1.005%.