【作者】 江洪；

【导师】 何潮洪；

【作者基本信息】 浙江大学 ， 化学工程， 2004， 硕士

【摘要】 综述了国内外黄酮类物质提取、超声辅助提取的研究进展，概述了功率超声作用原理，并对文献中有关超声提高提取速率和得率的报道进行了比较。 采用一般溶剂浸取方法较系统地研究了各因素(溶剂、温度、粒径、浸取时间等)对葛类异黄酮浸取的影响，异黄酮含量分析采用紫外分光光度法。各影响因素对浸取影响大小依次为：溶剂＞温度＞粉末粒径＞时间。 利用功率超声促进浸取，研究了恒温与非恒温下超声对提取的影响，重点考查了超声强度、超声作用时间对不同溶剂(水、乙醇水溶液)浸取的影响。恒温下，当超声强度超过某一值后，其浸取速率高于搅拌浸取，超声功率越高浸取速率越高，得率提高也很明显。同时在一定超声功率、一定溶剂体积情况下考察了圆筒型提取器的高度直径比对总异黄酮有效成分提取速率和提取得率的影响。对给定的超声功率，存在一个最佳的H／D值(约为0.58)使提取得率达到最大，该结果对于超声提取设备的优化设计和工程应用具有重要的参考价值。 根据实验现象，认为超声促进传质的主要原因是超声对颗粒表面的强剪切作用使颗粒破碎从而使传质面积增大。对于葛藤异黄酮的超声提取而言，在一定的时间后葛藤颗粒几乎都被破碎，根据受力平衡确定了超声强度与超声破碎粒径之间的关系，从而得到超声浸取时异黄酮浸出得率与超声强度的关系： Y_t／Y_∞=1-6／(π~2) sum from n=1 to ∞ 1／(n~2) exp(-n~2 Ptk_D) 其中，k_D为与超声提取器、提取溶液等特性有关的常数。模型拟合数据与实验数据符合较好，对乙醇水溶液和水系统，拟合的平均相对误差为1.005％。更多还原

【Abstract】 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%.更多还原