The Extraction And Properties Characterization Of Tea Saponins From The Tea Seeds

Tea seed meal is a natural raw material for extracting tea saponins, whichcan be obtained from mechanically pressed tea-seeds. The tea saponins arenatural non-ionic surfactants, which have good surface and biological activities,and can be applied in agriculture, textiles, building materials industry, daily-usechemical industry and other field., But for a long time, tea saponins developedslowly in its promotion and application for the main factors such as thecomplexity of the extraction process, the high energy consumption, deep color ofthe extracted product and low purity. In this paper, the extraction process andproperties of tea saponins are studied, They were described as follows:(1) Tea saponins were extracted from tea seed meal through a method offirst ultrasonic pretreatment and then water bath extraction, and the influences ofall technological parameters such as solid-liquid ratio, the volume fraction ofethanol, ultrasonic frequency, ultrasonic time, pH value, extraction temperature,extraction time on the yield of tea saponins. The optimum condition of the teasaponins in extraction process was: solid-liquid ratio (1:9); the concentration ofethanol (80v/v); ultrasonic frequency (25.87kHz); ultrasonic time (10min); laterextraction temperature (70°C); later extraction time (2h) and pH value (8). Underthis condition the purity of tea saponins were up to86%and the yield reached21%. Ultrasonic assisted ethanol extraction technology not only improvedextraction efficiency but also obtained a better color product. which had higherpurity、 yield and laid a solid foundation for industrial-scale production of teasaponins.(2) In order to discuss the influence of several single factors on the productrate, L39(4) nine of orthogonal experimental was designed by orthogonalsoftware. The concentration of ethanol, solid to liquid ratio, extractiontemperature, extraction time were chosen and they were set at three levelsrespectively. The results showed that the extent of the effects of four factors on the yield of tea saponins were: the concentration of ethanol> the ratio of solid toliquid> extraction time> extraction temperature, and the optimal combinationwas that the solid-liquid ratio of1:10, the concentration of ethanol of75%,extraction temperature of70°C, extracting time of1.5h.Under this condition, thepurity of tea saponins can reach22%.(3) The tea saponins were puried and treated with a series of test such asmelting point, color reactions, surface tension, contact angle and foamability.The result showed the melting point of tea saponins was about213°C~220°C.The tea saponins were characterised by two features color reaction. One was thatthe reaction of tea saponins and10%α-naphthol-ethanol solution present apurple ring. The other was that when tea saponins reacted with acetic anhydride,at the beginning the mixed solutions was separated and then displayed red in theshaking, at last turned purple after standing for a long time. Surface tension testshowed the critical micelle concentration of the surfactant was0.78%and theminimum surface tension value was41.43mN/m. The contact angle θ value ofthe aqueous solution of tea saponins was48.64o, far less than90o, suggest goodwettability that it could be used as a wetting agent. Its high foaming ability andfoam stability made tea saponins be applied in washing chemical industry andbuilding materials industry field.