Caffeine in Tea
Hey there, in this post I’m going to try to tell you all I know about the caffeine content of tea and try to examine common knowledge and existing myths.
Here I will only write about tea from the camelia sinensis variety. Most other ‘teas’ that don’t come from the camelia sinensis, like for example rooibos, peppermint or cargula naturally don’t contain caffeine, the most famous exception being Yerba Mate.
Caffeine or theine
Caffeine was first discovered in 1833 and was called theine at that time. Later on they discovered the chemical substance of caffeine or theine is the same, it is the same odorless, bitter, stimulating and easily solvable substance. But this does not mean that the caffeine of coffee has the same effect on the human body as the caffeine of tea. There are other factors involved.
The amino-acid L-theane
The amino acid L-theane is the most important reason caffeine in tea is ‘different’ from caffeine in coffee. Let me explain: L-theane interacts with caffeine which causes caffeine to be much slower in having an effect. This explains why tea causes a much more steady boost in mental awareness without the crash often associated with coffee. L-theane also causes the body to relax and calm.
How much caffeine in is tea?
This is really hard to say, it is different for each tea and there are a lot of factors you have to take into account. If you absolutely want an answer I would say about half that of coffee. But this is a poor answer as teas differ so greatly from each other in caffeine content.
Does the type of tea (Green, white, black or oolong) matter?
The most usual myths one encounters with this questions is that white tea does not contain caffeine and that black tea contains more caffeine than green tea. Both are wrong.
A study published in 2005 in the Journal of Food Science, talks about the exact contents of an amazing amount of food products. In that selection 77 different teas were tested. The results were all over the place, the caffeine content in each tea type differs immensely, not showing any connection between caffeine content and tea type.
So to put it clearly you can’t predict the caffeine content by the tea type. And to get back into the tea myths the tea with the most caffeine in that particular study was White Tea!
In 2008 another similar study was published in the Journal of Analytical Toxicology and their results confirmed the same tendencies.
Oxidation doesn’t increase caffeine content
Another common myth, probably related to the earlier one about black tea having more caffeine than green tea. But there is no evidence that this is the case, as higher oxidation teas do not have more caffeine content in general.
Factors that do influence the caffeine content of tea
The temperature of the water
When you use hotter water, with the same amount of tea and for the same time more of the caffeine naturally present in the tea plant will dissolve in the water.
The amount of tea leaves
Quite clear, the more tea leaves you use the more caffeine will be in your tea, with the same temperature and brewing time.
The brewing time
The longer you brew your tea the more of the caffeine in the tea leaves will come out.
What part of the Tea plant is used for the tea?
Teas can be made of different parts, that can consist of leaves, buds or stems. Usually they are a mixture of some or all of these. Buds are of course in fact small young leaves. The caffeine content is highest for the youngest leaves, followed by the young leaves and the mature leaves. The stems contain very little caffeine. Caffeine in the plant is a natural protection system against predators, that would prefer the rich young leaves. Another explanation is that the young, tiny leaves already have all these minerals, antioxidants, while larger leaves have the same but not more, for a larger weight and volume.
The size of the tea leaves
With the same settings on temperature, amount of tea, and time, the size of the leaves matters too. The bigger the surface the more caffeine. So teabags generally give away there caffeine the quickest then very small leaves and so forth.
The cultivar of the tea
There are thousands of tea cultivars, similar like there are for example a lot of varieties of apples like honeycrisp, jonagold and cortland. But two tea ‘main’ branches are the Assam variety and the Sinensis variety, the Assam having aside from other differences bigger leaves, and a higher caffeine content.
It seems that teas that are heavily roasted, for example the Japanese hojicha and some oolong teas, do contain a lot of caffeine. It seems to depend on the amount of roasting. Hojicha has almost no caffeine left where with oolong tea it really depends on each type.
The caffeine level differs quite a lot depending on the region it comes from. In general the higher the elevation of the garden the more caffeine the tea contains (and the better the tea is). One reason for this could be that the plant doesn’t grow that quickly at these heights and therefore the minerals per size would be higher.
Can you ‘decaf’ your tea by doing a short brew and throwing that water away.
Well it will certainly help lowering the caffeine content of the tea since a lot of it comes out in the first minute(s). But that being said there is no way to obtain completely 100 procent decaf tea. There is always a bit that stays there. If you want ‘real’ decaf tea you would probably be better off with an herbal infusion.
Now go out and enjoy some pure loose leaf tea!