Caffeine in Tea
Like no other means has caffeine conquered every day thanks to its naturally stimulating effect on our lives, but especially our morning routine caffeine.
Caffeine, though, is not always equal: Only in the tea leaf meets the natural stimulants on the amino acid theanine, which is responsible for flavour and aroma not only, but also a calming effect on the body has, which counteracts the caffeine kick and gentler to a, more uniform drive makes - the so-called tea-effect.
The three main chemical components in tea are:
3. Essential oils.
3. The Essential Oils - The oils are responsible for the aroma and most of them are volatile. If tea is stored too long or in an unsuitable way these substances will evaporate and with them the smell and taste of the tea leaf.
2. The Polyphenols - These are the biggest and most interesting group. Often this group was/is called tannic acid. This is not correct because there is no tannic acid in tea. These names were given before the exact chemical structure of tea was known. Polyphenols are responsible for the colour, for the sometimes astringent taste and above all for the health benefits of tea.
1. The Caffeine - Monks first discovered it and we all grown to love it. The caffeine in tea is responsible for these effects:
- it stimulates the central nervous system
- high level of concentration
- less reaction time
- refreshing with increased general alertness
- stimulates the cardiac muscle without raising blood pressure
- has a diuretic effect
- stimulates the respiratory system
- delays fatigue
Tea leaves contain about 5% caffeine (it was called theine first but it is chemically exactly the same). There is more caffeine in the tips and the first two leaves than in the other parts of the plant, therefore, some of the best Darjeeling teas are quite rich in caffeine. Smaller tea grades, like "Dust" and "Fanning" in tea bags, release more caffeine quicker than the intact leaf. Unlike in coffee the caffeine in tea is slower to be absorbed by the human body and stimulates the central nervous system. This results in an increased brain activity after about 30 mins and lasts between 1.5 and 3 hours. Caffeine in coffee is absorbed quickly into the blood circulation, stimulates the heart (increased heart beat and blood pressure) and lasts for 30-60 mins. After the stimulation wears off the body is more exhausted than before the intake of coffee. The following graph shows the different effects of caffeine in tea and coffee:
View Graph (Above)
A unique feature of tea is the possibility to regulate the effects of caffeine to a certain degree through the brewing time: 1-3 mins more stimulating 3-5mins less stimulating, relaxing at the same time. This is possible because of the chemical partnership between caffeine and the polyphenols. The amount of caffeine is always the same in tea but after about three minutes most polyphenols are fully resolved and counterattack the stimulating effect of the caffeine. That means the concentration level is still high but the muscle activity is low which creates the unique feeling of being mentally alert without being "jumpy". Despite the gentle way the caffeine in tea effects the human body it is not suitable or only in small quantities for people with heart diseases, pregnant women and it can prevent sleep when taken to late in the day. If you do not want to renounce tea completely there are types with less caffeine or even none. As a rule the longer the fermentation of the tea takes the higher the caffeine content. That means that green tea possesses less than the half fermented Oolong which again contains less than black tea. There are some exceptions, for example, the black Chinese Keemun tea contains only small amounts of caffeine while the green Japanese Gyokuro tea has almost as much as a black Darjeeling tea.
The South American Mate tea is almost as caffeine rich as coffee while the South African Rooibush tea contains no caffeine at all. It is also rich in vitamins which makes the Rooibush an ideal tea for children, pregnant women and everybody who should not consume caffeine at all. Please note that decaffeinated tea is not completely caffeine free which is not possible without destroying the tea.
By no means is this bit of science taking away from coffee's sweet sweet caffeine hit. It is just a means of comparison with something that is familiar. Lesson, drink more tea.