When drinking coffee, the invigorating effect of the caffeine is almost immediate, but it is often rather shortlived and accompanied by palpitation or nervousness. In Green Tea the invigorating effect sets in slower but lasts longer and is less prone to causing palpitation or nervousness.
This is because while the caffeine in coffee is resorbed in the stomach, it is bound to the tanning agents in green tea which are resorbed later by the bowels.
Because of this difference in the resorption and effect caffeine and theine used to be falsely distiguished as two seperate agents.
Analyses of the KEKO Teas have shown that the caffeine content differs depending on the time of picking. As shown in the graph, teas from the second picking like the Kabuse No.2 and Benifuuki No.2. had the highest caffeine content. receding again in later pickings. The tea from the late autumn harvests like Aki Benifuuki, Aki Bancha and Ginger Lemon Bancha are lowest in caffeine.
Apart from the time of picking the processing of the tea also has an influene on its caffeine content. For example Kukicha is a stem tea that contains only little leaf tissue and therefore a smaller amount of caffeine (similar to Aki Benifuuki).
Finally you can influence the caffeine content of your tea by the method of preparation you choose. The coffeine extract in your tea will be lower, the more you reduce the temperature and infusion time. Obviously consuming the entire leaf will also allow you to absorb its full contents. You can do this by either eating the tea leaves after the infusions (for example in smoothies, pesto, muesli or yoghurt) or by drinking Matcha or Kabuse Powder.