Process Optimization And Degradation Kinetics For Microwave Vacuum Drying Of Different Traditional Chinese Medicine Extract

Different herb extracts were dried by microwave vacuum drying (MVD) technology. According to the researchs, the operation parameters of MVD process were investgated, which contributed to the foundation of technical standards and application rules of MVD technology for herb extracts. The main researches are listed as follows:(1) The effects of microwave power, drying time and other factors on the water content of the drying product of radix paeoniae rubra (RPR) was studied by single factor tests. Based on the results of the single factor tests, the process was studied by using orthogonal test design and multi-index grading method on the parameters of the water content of dried product, the retention rate of paeoniflorin and the drying rate of RPR extract. The optimum microwave vacuum drying process of RPR are listed as follows:the microwave power 3 kw, the drying time 8 min, and the sample amounts 150 g.(2) To investigate the effect of microwave output power, sample amounts and intermittent ratio on the dagradation kinetics of Danshen extract, to calculate the change of water content and the salvianolic acid B content and tanshinol content during the microwave vacuum drying process of danshen extract. The method of chemical kinetics was used, and the change of salvianolic acid B content and tanshinol content were determined by high performance liquid chromatography (HPLC).The'Results show that the content of salvianolic acid B was decreasing and the content of tanshinol was increasing during the microwave vacuum drying process. The relative content of salvianolic acid B (lgC) with drying time (t) was shown in linear correlation. The degradation reaction of salvianolic acid B is a first grade kinetics reaction during the microwave vacuum drying process.(3) To investigate effect of different microwave drying conditions in honeysuckle extracts on the change of water content and the chlorogenic acid content during the microwave vacuum drying process, the methodof chemical kinetics was used for the data analysis and the high performance liquid chromatography (HPLC) was used to determined the chlorogenic acid content. The results shows the chlorogenic acid content decreased during the microwave vacuum drying process and the chlorogenic acid content (lgC) with drying time (t) were shown in linear correlation during the microwave vacuum drying process. The degradation reaction of chlorogenic acid was a first grade kinetics reaction. The chlorogenic acid degraded less when optimum process (1380 w,intermittent ratio 1,70 g) was adopted.