The progress of the concentration technology of extract of traditional Chinese medicine

The concentration of extract of traditional Chinese medicine (TCM) is one of the important unit operations that affect the quality of the pharmaceutical products. However, there are some problems to be solved. The concentration process has the shortages of relatively high temperature, relatively long time or low efficient, some losses of active and volatile ingredients, more operation steps, easy fouling and emission of waste water. In order to solve these problems, many new technologies and installations have been developed in the past thirty years, including suspension freeze-concentration, progressive freeze-concentration, single- or multi-effect evaporation with an external natural circulating flow, on-line preventing fouling evaporation with vapor-liquid-solid flow, reverse osmosis concentration, membrane distillation, osmotic distillation, macro-porous resin adsorption etc. The system of the extract of TCM is very complex. The extract includes water and alcohol extracts. The composition of TCM is made of active and inactive ingredients. Hence, it is necessary to master the features of every concentration technologies and installations, including their merits and demerits, flexibilities, degree of maturations of techniques and so on to get a wise choice for the industry applications. New concentration technologies and installations of the extract of TCM developed recently are reviewed in this paper. The characteristics of each method are analyzed and discussed in order to guide the industry applications. At the same time, the further research directions of concentration techniques of extract of TCM are also given.