Plant extracts are naturally extracted substances from plants, mainly used as raw materials for natural medicines or plant-based medicines, health foods, cosmetics, and food additives. On the one hand, with the growing popularity of the "return to nature" movement worldwide, herbal medicine and natural foods have become popular medications and foods in the 21st century. On the other hand, as society develops and living standards improve, people's attention to diseases has shifted from simple treatment to disease prevention, making functional natural health foods highly valued.
Since the late 1990s, plant extracts have been increasingly important in the pharmaceutical and food industries and have become an important link in promoting the modernization and technological innovation of traditional Chinese medicine and an effective way to enter the international market. The plant extract industry has become one of the rapidly developing industries in China. Modern separation and purification technologies integrate membrane separation processes into plant extracts, improving the separation efficiency and product quality. Inorganic ceramic membranes have significant potential in the plant extraction industry due to their characteristics that allow them to adapt to extract conditions in water and solvents.
Ceramic membranes are a form of fluid separation process called "cross-flow filtration": the raw material liquid flows at high speed in the membrane tube and, under pressure, the clear permeate containing small molecular components permeates out of the membrane in the direction perpendicular to it, while the turbid concentrated liquid containing large molecular components is trapped by the membrane, thereby achieving the purpose of separation, concentration and purification of fluids.
Traditional clarification methods for juice production are complex, expensive, and energy-intensive, which easily leads to loss of flavor and nutrition. Organic membrane clarification methods have drawbacks such as membrane pollution, high cleaning costs, and easy destruction of fruit juice color and taste. Inorganic ceramic membrane clarification technology can not only compensate for the shortcomings of traditional clarification technology and organic membrane clarification technology but also reduce protein content. Pectin adsorbs large molecules such as starch on the membrane surface, reducing membrane pollution and achieving high membrane permeation flux and retention rate. Therefore, it has been widely used in fruit juice beverage processing.
Using inorganic ceramic membranes in juice production can not only reduce energy consumption but also obtain high-quality juice, most of the aromatic components can be retained, and the liposoluble components are complete, which is almost the same as the fresh juice after concentrating with ceramic membranes. Due to the sterilizing effect of the membrane and the absence of undecomposed pectin in the filtrate after acid treatment, precipitates will not occur during long-term storage.