Preparative Separation Of Tea Polyphenols With Ultrafiltration-macroporous Absorbent Resin

Tea polyphenols（TP） are one of materials with great physiological activities,such as antihyperlipidemia, anticancer or antitumor, and antibacterial or antivirus.This study aimed to explore a safe, efficient tea polyphenols extraction method, sothat high-quality tea polyphenol products could be obtained which could beapplied to the food and pharmaceutical industries.This thesis mainly studied the conditions of extraction of tea polyphenols. Inthe process of extraction of tea polyphenols, the optimum conditions of extractionwere determined by the orthogonal experiment. The optimum conditions were asfollows: the temperature of extraction was90℃, the time of extraction was30minutes, the ratio of tea and solvent was1:25, the times of extraction were4, themaximum yield of tea polyphenols was23.68%under this condition.Adding ultrafiltration before the resin absorption, the optimal conditions ofultrafiltration were identified as follows: operating pressure0.4MPa, operatingtemperature25℃. It can keep84.07%of tea polyphenols under this condition.The macro-porous resins were used for the purification of tea polyphenols.The NKA-2resin was adopted after investigating some kinds of resins’sperformance. Based on single factor tests, key parameters of resin adsorption withresponse surface analysis methods were studied. The optimal process conditions:the diluted times was5, adsorption pH was2, and2.9h adsorption time. Underthese optimized conditions, the adsorption rate of tea polyphenols was90.28%.According to the investigation on the desorption process, the result showed that85%ethanol had the best desorption capacity, and the optimum temperature, pH,and time were25℃,2, and2h.The best dynamic adsorption conditions were found to be polyphenol samplevolume was6times of the bed volume（BV）, at a flow rate of4BV/h. Whereas theoptimal dynamic desorption conditions were found to be a flow rate of2BV/husing3times BV of85%ethanol for elution.The study of thermodynamic characterization showed that the adsorptionisotherm of the adsorbent could be described by the Langmuir equation. And itbelonged to the preferential isotherm. The constant of equilibrium rate of NKA-2was K=0.72h^-1, the matter transfer zone was short, which put good use of NKA-2. Tea polyphenol products were analyzed by HPLC, the results indicated: totalcatechins was about69.12%, the content of EGCG was41.21%, the content ofEGC was11.51%, the content of ECG was10.96%, the content of EC was5.44%,caffeine content was0.89%.The content of tea polyphenols reached91.28%and yield was9.74%underabove-mentioned conditions.