Study on the extraction technology of caffeine from Lung-Ching green tea

The extraction technology of caffeine from Lung-Ching green tea and the technical conditions of alternation and optimization are studied to offer some considerations for the extraction of caffeine from Lung-Ching green tea.Firstly,the effectiveness of soxhlet extraction is detected,and then follows the extraction technologies of microwave-aid method and ultrasound-aid method.The optimal conditions for microwave-aid extraction are set as the following:the liquid-solid ratio is 20:1,the heating time with defrost choice of microwave is 3 minutes,the maximum extraction ratio in the three extractions is 3.69%.The optimum condition for ultrasound-aid extraction are determined as follows:ultrasound power 100%,twice treatments of ultrasound for 25 minutes,the liquid-solid ratio 25:1,temperature 80℃,and the maximum extraction ratio 3.77%.This result indicates that the effectiveness of microwave-aid extraction and ultrasound-aid extraction is distinctly better than that of soxhlet extraction,but no significant differences exist between microwave-aid extraction and ultrasound-aid extraction.