Koffein In 1819, the chemist Ferdinand Ruge was the first to succeed in isolating pure caffeine from coffee beans. In 1827, the caffeine in tea was discovered and called "Teein". The realization that the caffeine in coffee and tea are chemically identical has resulted in today's standardized use of caffeine in reference to both tea and coffee. Caffeine acts as a stimulant on all parts of the central nervous system, manifest in increasing mental absorption, abolition of fatigue, and a certain elevation of mood. Furthermore, it has been possible to demonstrate an improvement in learning processes as well as a reduction in reaction times. Caffeine increases the output of the heart, thus increasing the blood flow through the internal organs. In contrast with the caffeine found in coffee, which causes a quick but short "hit", the caffeine in tea acts as a mild, but longer lasting stimulant. Caffeine in tea is not found in its free form, but in chemical combinations. It is partly bound to the amino acids, partly to the tanning agents. Even though this is still a matter of controversy, evidence points to the conclusion that the part of caffeine bound to the tanning agents is not absorbed by the body and thus has no effect. The caffeine in coffee is transported via the bloodstream to the adrenal cortex, where it immediately causes the release of the stress hormone adrenaline. By contrast, the bound caffeine in tea attaches itself to the two main nervous cords of the vegetative nervous system (sympathetic and parasympathetic nerves). Only then does the body stimulate the adrenaline production in the adrenal cortex, causing a continuous stimulation and not a stress release as after coffee. Effect of caffeine in tea Short brewing time = stimulating bereits After only one or two minutes, the majority of the caffeine is transferred to the tea infusion, but only a small proportion of the tanning agents, which would act to reduce the effect of the caffeine. Long brewing time = calming After 4 to 5 minutes, the higher proportion of tanning agents results in a calming effect. Adding milk, cream, candy, etc can now soften the increased bitterness of taste. Theanin Theanine is belongs to the chemical group of amino acids; its effect is also to absorb the stimulating effect of caffeine. If the tea is left to brew for long periods, this substance dissolves completely.