Aqueous Ethanol Extraction Process Of The Tea Polyphenols, Ion Precipitation - Flocculation In The Purification Of The New Technology Research

This paper introduced a new technology of extraction and separation of tea polyphenols (TP). Extraction process of TP and caffeine (caf) by mixed solvent composed of water and alcohol, scale-up law of agitating tank, ion precipitation process and flocculation process for TP were studied thoroughly. During extraction process, the effects of different factors on the extraction rate of TP and caf were investigated experimentally, and the optimum conditions were volume percentage of alcohol 50%, solvent 7ml/g, extracting temperature 60℃, and extracting time 35min. By means of two-step cross current extraction method, the extraction rate of TP can be more than 90%. Compared with traditional method, this extraction process can reduce the solvent dosage, decrease the volume of extraction liquor, shorten the extracting time, and lower the energy consumption.The results of magnification experiments show that critical suspension speed is an ideal scale-up method and the extraction process is controlled by interior diffusion within a certain agitating rate.After the metal ion precipitant were selected, factors which affect the precipitation rate such as precipitating media, the mass of precipitant, precipitating temperature, and precipitating pH were discussed and the optimum conditions were obtained. The result shows that precipitated in the medium of mixed solvent, caf has little coprecipitation, therefore it can be removed more (that is about 30%) than in water.Based on the property of caffeine, TA, which is a kind of natural food additives, was used as flocculating agent to remove caffeine from the precipitation transformation solution. This flocculation process can avoid using noxious organic solvent chloroform and raise the safety of production process.