Ultrasonically Assisted Flavonoids Extraction From Bamboo Leaf

The state-of-art review in flavonoids 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 stir rotation speed to extraction were researched. The flavonoids were analyzed by spectra-inspection. And the effect of the factors to extraction is solvent>temperature>granularity> stirring.Ultrasonically assisted extraction (UAE) was investigated. The influence of ultrasonic intensity to different solvents (acetone solution, alcohol solution, water and so on) extraction was mainly studied in constant temperature and no temperature adjustment. Under the condition of constant temperature, the rate of UAE were better than the stirring extraction after the ultrasonic intensity reached a certain amount, and the rate increased with the ultrasonic intensity, but the increase would be gradually slower as the ultrasonic intensity increased.A model for UAE was proposed. Based on the experimental phenomena, the reason of promotion in extraction rate by UAE was regarded as: the cutting of ultrasonic would crash the original larger bamboo particles into smaller particles, thus increasing the surface. Limited by the efficiency of ultrasonic utilization, only part of the original bamboo particles were crashed. According to the principle of force balance to the bamboo particles, the relation of r*(the minimum size that a certain intensity of ultrasound could crash the bamboo particles to) with the intensity of ultrasound was proposed. The total leaching quantity was the sum of leaching quantity of original particles(R) and the crashed particles(r*). The final equation of the model is:Where Yt and Y?were the yield of flavonoids in the leaching time of t and 鞍 respectively, ko and k are constants that only depend on the extracted materials (bamboo leafs).The model can correlate the ultrasonically assisted experimental data (acetone solution, alcohol solution and water) well. The average relative error is 2.11%. Furthermore, the ultrasonically assisted experimental data for acetone solution and alcohol solution could be predicted using the parameters ko and k obtained from the ultrasonically assisted experimental data for water.