Study On Extracting Effectual Compositions From Plants By Vacuum Microwave Pretreatment

Natural plants contain a diverse group of bioactive substances with a broad range of applications in medicine, healthcare product and cosmetic etc. China is rich in medical herb resources, but has a weak market share (less than 5%) on plant extractions in the world. Because effectual compositions of plants were a little and the extraction process needs a lot of solvent and energy, the extraction is the most important unit operation,which affect production quality, cost and utilization ratio of material directly. Therefore, it is important to develop high efficient and energy-saving extract technology and equipment which will lead acceleration the process of modernization of Chinese medicine, exploiting and utilization the resources of herbal medicine in our country in higher efficient.The method of vacuum-microwave pretreatment is proposed and used in current study, the materials were wetted for some time in advance, then were irradiated by vacuum-microwave to destroy cell's structure of plants, and then the traditional extraction was employed in succession. During the microwave irradiation, microwave energy was nearly all absorbed by the solvents which moved into internal area of cell during wetting and the total irradiation time was about 2-3minutes because the materiels were just wetted by limited solvents. The effectual compositions are retented and the extraction efficieny is higher due to the shorter treatment time, lower pressure and destruction the wall of cell. Furthermore the water was employed as vaporized solvents in current method because vacuum in the microwave cavity was imposed resulting in lower vaporization temperature, it is safer and lower cost than ethanol or other solvents is used.The effects of vacuum-microwave pretreatment on extracting effectual composition from Ganoderma Lucidum and Bamboo leaves were studied. First, the extent of cell-wall breaking by vacuum-microwave irradiation was observed and checked by SEM. The pictures of SEM showed that cell-walls were almost destructed after microwave irradiation. The Ganoderma Lucidum and Bamboo leaves were pretreated by vacuum-microwave in advance, then the conventional water-bath extraction was employ, and the effectual compositions extraxtion rate, turbidity and viscosity of extracts were tested and analyed. The vacuum-microwave irradiation parameters were optimized and confirmed by response surface methodology. Compared with the traditional water-bath method,the results showed that the current method can not only shorten the time of extraction but increase the rate of extraction of effectual compositions.A kinetic mathmatical model for extraction process after vacuum-microwave pretreatment was also studied, which is based on the revised Fick's first law of diffusion. The experiment datas matched the kinetic equation well. Therefore it provides a theoretical reference for the vacuum-microwave pretreatment extraction of Chinese traditional medicine. The results show that vacuum-microwave pretreatment is a perfect assisted extraction method, which can destruct the cell-wall of plants rapidly, shorten extraction time and increase extraction rate.