Technology for removing caffeine in tea

The invention belongs to the technical research field of natural product extraction and separation processes. By adopting an MCI-GEL (Middle Chromatogram Isolated Gel) column chromatography, using a certain ratio of ethanol-water as an eluent, and combining water decoction, vacuum distillation and other processes, caffeine-free instant tea can be prepared by green tea, black tea and the like. The technology is simple in process, relatively low in cost and non-toxic. The product is suitable for people who are excitable when drinking tea and are difficult to sleep after drinking tea at night. In addition, the tea leaves with poor appearance or tea stems can be prepared by the process into salable products. Furthermore, bitter ingredients in the tea can be removed, and thus the taste can be improved by the process. The process retains tea polyphenols, polysaccharides, amino acids and other ingredients. The resulting caffeine-rich by-product can also be used as a raw material for preparing caffeine in the future.