Purification Of Tea Saponin From Camellia Seed Meal By Ethanol Extraction And Supercritical CO₂ Extraction

Camellia oleifera is an important cash crop in China.A large amount of camellia seed meal is produced in the production of camellia oleifera oil every year,accounting for about 75%of the total camellia oleifera seed output.Camellia seed meal is rich in a variety of active substances such as tea saponin,tea polyphenols,tea polysaccharides and so on,among which the tea saponin content is 10%-20%.Tea saponin is a natural surfactant and antioxidant with superior performance,which is widely used in daily chemical industry,agriculture,medicine and other fields.The price of tea saponin is greatly affected by its purity,and the price will be increased several times or even tens of times when its purity is increased by 10%.However,the traditional tea saponin extraction method has disadvantages such as complicated process and large amount of solvent affecting product quality.Supercritical CO₂ extraction technology is a popular green chemical separation technology in recent years,which can not only improve the purity and yield of the extracted substance,but also retain the biological activity of the extract to the maximum extent.In this paper,camellia seed meal is used as raw material.Firstly,tea saponin with high purity and high yield is obtained through ethanol extraction combined with flocculation purification.Secondly,tea saponin is refined by supercritical CO ₂extraction.（1）Ethanol extraction combined with flocculation precipitation method was used to preliminarily extract tea saponin.Using defatted camellia seed meal as raw material,the effects of extraction temperature,extraction time,ethanol concentration and liquid-solid ratio on the extraction effect of tea saponin were investigated.The results showed that at the extraction temperature of 70℃,ethanol concentration of 70%,liquid-solid ratio of 10:1 m L/g,extraction for 1 h,The concentration of 0.1wt%20 m L chitosan solution for tea saponin concentration purification,tea saponin purity can reach 81.8%,the yield is17.42%.In addition,the purification effect of different composite flocculants（chitosan+polyacrylamide,chitosan+polyaluminium chloride,polyacrylam ide+polyaluminium chloride）on concentrated tea saponin extract was investigated.The experimental results showed that chitosan+polyacrylamide composite flocculant had the best performance in tea saponin purity and impurity removal rate.Secondly,the influence of compound flocculant addition amount,standing time,flocculant concentration,proportion of flocculant and other factors on the purification effect of concentrated tea saponin extraction was studied,and the optimal flocculation and purification process conditions were obtained.The results showed that under the experimental conditions of adding 25 m L compound flocculant,concentration 0.07%,ratio 1:1,flocculation time 150 min.The final impurity removal rate was 30.53%,the loss rate of tea saponin was 5.52%,and the purity of tea saponin was 87.3%.The yield was 16.85%.（2）Using supercritical CO₂ extraction technology to refine crude tea saponin,using tea saponin with crude extraction purity of 80%as raw material,explore the effects of supercritical pressure,supercritical temperature and supercritical extraction time on tea saponin refining effect.Under the extraction temperature of 70℃,extraction pressure of 25 MPa,CO₂ flow rate of 2 m L/min,extraction time of 2 h,The purity of tea saponin was 87.9%by supercritical extraction.The properties of tea saponin before and after supercritical extraction were compared from the aspects of surface tension and foaming stability,and the material structure of tea saponin before and after supercritical extraction was characterized and analyzed by means of infrared spectroscopy and scanning electron microscopy.The results showed that supercritical CO₂ extraction kept the natural quality of tea saponin.In addition,it is superior to the tea saponin in foaming ability,impurity content and particle diameter,providing a new extraction and purification process for tea saponin with high purity needed by daily chemical and pharmaceutical industries.