膜技术富集儿茶素渣中茶氨酸效应研究

以茶叶深加工中提制儿茶素后的废料—儿茶素渣为材料,在筛选出膜分离与富集茶氨酸最适料液pH值的基础上,比较研究了截留分子量为2500 Da、3500 Da、5000 Da的膜超滤儿茶素渣料液对茶氨酸得率与纯度的影响,以及300 Da纳滤、200 Da纳滤、反渗透、真空蒸发浓缩四种浓缩方法对茶氨酸的效应。结果表明:调节料液体系的pH值至2.8～3.5左右,有利于在超滤过程中分离与富集茶氨酸;选用截留分子量为3500 Da膜超滤儿茶素渣料液,茶多酚、水溶性碳水化合物等大分子物质大部分被截留,其截留率分别为89.90%、92.20%,可获得率为54.50%、纯度为8.92%的茶氨酸料液,300 Da纳滤、200 Da纳滤、反渗透、真空蒸发浓缩四种浓缩方法在加工茶氨酸中,茶氨酸损失率依次为4.51%、3.62%、0.45%、5.15%。综合考虑,利用3500 Da超滤分离与反渗透浓缩可以分离与富集儿茶素渣中的茶氨酸,综合得率与纯度分别为54.05%和8.53%,在生产上具有一定的可行性。

Study on Separation and Concentration of Theanine in De-catechined Tea Extracts by Membrane System

By using the material of de-catechined tea extracts in tea comprehensive processing and on the basis of selecting the best pH value of liquid for separation and concentration theanine by ultra-filtration,the effect on the yield rate and purity of theanine by 2500 Da、3500 Da、5000 Da ultra-filtration and four concentrating method of 300 Da nano-filtration、200 Da nano-filtration、reverse osmosis、vacuum vaporation concentration were comparatively studied in processing the de-catechined tea extracts.The results indicated that it was beneficial to separate and concentrate theanine from de-catechined tea extracts when the value of pH was 2.8~3.5.3500 Da ultrafiltration had a good effect in separating and concentrating theanine,the major tea polyphenol,water soluble carbohydrate were preserved and the cut rate reached 89.90%、92.20% respectively,the yield rate and purity of theanine was 54.50%,8.92% respectuvely.The lost rate of theanine in concentrating of 300 Da nano-filtration 、 200 Da nano-filtration、reverse osmosis、vacuum vaporation concentration was 4.51%、3.62%、0.45%、5.15% respectively.Take all thing into account,it is feasible to separate and concentrate theanine from de-catechined tea extracts in tea comprehensive processing industry by the joint application of ultra-filtration and reverse osmosis,and the yield rate and purity of theanine can reach 54.05% and 8.53% respectively.