An attempt to extract L-theanine and caffeine from Ilex Guayusa
Usually the steeping times of tea or guayusa are too short to really extract a therapeutic amount of theanine. The recommended brewing instructions of a few minutes mostly help to extract the caffeine and a desirable flavour, but by modulating the temperature, extraction time and ratio of water-to-guayusa leaves (and their particle sizes) one can have significant impacts on the extraction yield of theanine. Furthermore the absence of tannins in the guayusa leaf make it an ideal candidate (as opposed to tea) to steep the leaves for a prolonged length of time. The flavour actually intensifies in a positive manner. And the texture thickens. A creamier mouthfeel.
Flavour wise pure theanine contributes to a complex but favourable umami (savoury) taste. It exhibits a synergism with the common and controversial flavouring agent monosodium glutamate (MSG). The two combined lead to an additional enhancement of the umami taste experience. So theoretically you could add l-theanine powder to a soup or sauce to enhance it’s savouriness. Which is a radical idea when you know the very desirable physiological “side effects” of this compound.
I don’t know the optimal conditions for extracting theanine from guayusa using water, but I had a go at 80 °C for 60 min with a water-to-tea ratio of 20:1. (in the picture you have 12.5 g of guayusa leaves for 250 g of water).
After ingestion theanine is quickly absorbed into the bloodstream through intestinal absorption. From where it is transported to the major organs of the body, including the brain. Ingestion of theanine has been reported to facilitate the generation of alpha brain waves, which are associated with a relaxed but alert mental state. In addition, theanine is reported to promote the release of the inhibitory (and calming) neurotransmitter GABA which in turn regulates dopamine and serotonin levels in the brain.Thus, theanine consumption has been closely associated with relaxation and improved learning ability.