微波辅助循环萃取法脱除茶叶咖啡因研究

探讨了利用微波辅助萃取技术高选择性脱除茶叶中咖啡因的新方法,在料液比1∶50,微波功率160W,微波时间6min的条件下,以沸水为溶剂,咖啡因脱除率高达80.56%,茶多酚损失率为40.16%。优化工艺以茶叶萃取液为溶剂,采用循环萃取的方式,则可以控制茶多酚损失率降至12%。进一步探索性尝试4℃冷藏静置12h的方法进行萃取液循环利用,促使咖啡因以络合物的形式沉淀、脱除。在最优条件下,连续生产茶叶9批次后仍可保持47.02%的脱除率,并且茶多酚的损失率小于11.74%。

Study on removal of caffeine from tea with microwave-assisted cycle extraction

A new method was proposed to selectively remove caffeine from green tea leaf.When the solid to solvent ratio was 1∶50(g∶mL),using water as solvent,the removal yield of caffeine was 80.56% and the loss of total phenolics was 40.16% under a microwave power of 160W for a processing time of 6min.The tea extract was used as new solvent to remove caffeine for the first time.The results indicated that the removal yield of total phenolics was decreased to 12%.Moreover,it was found that,after an interval time of 12h,the caffeine could be removed by sedimentation effect from tea extract,and the tea extract could be used repeatedly for removal of caffeine from many batches of tea leaf.When the tea extract was used for processing the ninth batch of tea leaf,the removal yield of caffeine was still as high as 47.02%,while the removal yield of total phenolics was decreased to 11.74%.