I had someone ask me the other day, “Does Green Tea Have Caffeine?”. In answering this question, we got into a conversation about caffeine in general and the relative caffeine contents for various teas, in comparison to each other, and inevitably to coffee. What I realized is that there seems to be good amount of confusion when it comes to this topic.
To get a good answer, we need to step back and look at caffeine for a minute.
What is Caffeine? Caffeine, was discovered in 1819 by a German chemist, as a natural compound found in coffee. Later, around 1827, it was determined that tea contained a substance strikingly similar, while initially named “Theine”, it was later determined to be the same compound found in coffee and so the Caffeine name stuck and “Theine” was dropped. Caffeine can be found in varying quantities in the leaves and fruits of many different plants.
What is the role of Caffeine? Caffeine in plants acts as a natural pesticide killing off specific insects that attempt to feed off of the plants. In humans, as we know, it’s a central nervous system stimulant that can give us energy or the jitters depending on when we take it and how much.
What factors determine Caffeine content? There are many factors that determine caffeine content, most notably in tea and coffee, the factors include: variety, growing conditions, processing, preparation. Some studies have even shown that in tea the location of the leaf on the plant can affect caffeine level.
So how does tea stack up in the ranks for caffeine content Well, it depends.
Tea actually contains more caffeine than coffee, when measured in it’s dried form. Does this go against everything you thought? You’re not alone, fortunately for us, we don’t generally consume tea in it’s dry state.
Once prepared, tea in contrast to coffee, has about 1/2 to 1/3 the caffeine.
So now that we’ve got that straightened out, “Does Green Tea Have Caffeine?
Yes, but not as much as you might think.
Caffeine content varies by sample, but in general, this is how tea stacks up.
Black tea contains the most caffeine, while white tea comes in with the least. Below are the types of tea ranked in order by average caffeine content.
Black Tea – About 40mg per 8oz.
Oolong Tea – About 30mg per 8oz.
Green Tea – About 20mg per 8oz.
White Tea – About 15mg per 8oz.
What about decaffeinated tea?
Decaffeination is the process by which the caffeine is removed from tea. This can be green tea, black tea, oolong, whatever; any type of tea can be decaffeinated, though green tea and black tea are by far the most commonly seen decaffeinated.
There are two primary methods of decaffeinating tea, the first involves soaking the beans in a solvent, the second, water.
Water extraction is the most common, and involves soaking the leaves for a short period of time. To maintain flavor, the water can then be run through charcoal filter and then re-added to the leaves, where through the process of evaporation, the flavor can be maintained.
Decaffeinate your own tea
Because the majority of caffeine is released in the first 30-40 seconds of steeping, you can decaffeinate, or at least partially decaffeinate, your tea at home by steeping your leaves briefly, tossing the water and then steeping the tea.
I hope this has cleared up some of the confusion about caffeine and tea, and at the very least, you’ve learned more about caffeine than you ever wanted to know.
1. The World of Caffeine by Routledge
2. Caffeine by The Institute of Food Technologists’ Expert Panel on Food Safety & Nutrition, All About Tea by William H. Ukers
3. Internation Food Information Council, All About Tea by William H. Ukers