微波预处理强化山楂回流提取的作用机理

Enhancement Mechanism of Microwave-Pretreatment Technology on Reflux Extraction of Hawthorn

为揭示微波辅助技术强化中草药提取过程的机理,针对微波预处理-回流提取联合工艺,建立了提取动力学方程,并利用该方程模拟了山楂提取实验,探讨了微波功率和辐照时间对目标成分提取过程动态特性的影响.结果表明,回流提取时间均为2.5h,微波辐照80s,经65W和455W微波处理后的提取效果均较高,目标成分的提取量比未处理工艺分别提高了51.0%和47.7%.虽然上述不同功率水平的微波处理均能达到强化目标成分提取的效果,但微波强化提取的作用机制有所不同,前者在于材料内部较高的温度和含水量,后者在于较高的压力.微波作用主要通过2方面影响目标成分的提取动力学特性,一是影响目标成分与基质材料之间的解吸,二是影响基质材料内部的细微组织结构.

For the investigation of the enhancement on medicinal herb extraction, the extraction kinetic mass transfer mechanism of microwave-assisted technology equation of microwave-pretreatment reflux technology was developed and used to simulate the extraction experimental status of flavones from hawthorn. By the combination of extraction kinetic experiments of flavones from hawthorn and mathematical model calculation, the effects of microwave power and irradiation time on the kinetic characteristics of extraction process were discussed. The resuits show that with the same reflux extraction time of 2.5 h and irradiation time of 80 s, by the comparison with that of the un-microwave pretreatment, the extracts yields undergoing microwave-pretreatment at 65 W and 455 W have respectively increased by 51.0% and 47.7%. Although the effects of the above microwave-pretreatment at different power levels on the extraction of flavones from hawthorn are basically identical, studies show that the mechanism of microwave influence on enhancement extraction is different, the former mainly being due to the higher temperature and moisture content, and the latter mainly being due to higher pressure. There exists the following two ways of the influence of microwave on the extraction kinetic characteristics of extracts, one of which is the influence of microwave irradiation on the adsorptions of extracts from matrix, and the other of which is the influence of microwave irradiation on the micro structure of matrix.