The Dry Leaf: Why Processing Barely Touches Caffeine

Caffeine is an alkaloid from the methylxanthine group, one of three found in the tea leaf, alongside theophylline and theobromine. Green, white, and black tea are leaves of the very same plant, Camellia sinensis; the only difference between them is the degree of oxidation. And oxidation has almost no effect on the caffeine molecule.

This is confirmed by the Carloni study [2], in which a white tea, two green teas, and two black teas were made from a single cultivar, grown and harvested under identical conditions, at the same factory. The result: caffeine levels were similar across all the teas, except for the black CTC, which had the lowest. In other words, even the most oxidized tea in this experiment had less caffeine, not more.

Why? The decrease in caffeine during oxidation is related to the time and temperature of oxidation, while a small amount of caffeine is lost during drying through sublimation [3]. In other words, heavier processing, if it changes caffeine content at all, tends to lower it slightly.

Under equal conditions (same plant, same region, same cultivar), the difference in caffeine content between green, white, and black tea is minimal. The Chin et al. study [1], covering 20 varieties, showed that caffeine concentration in white, green, and black teas ranged from 14 to 61 mg per serving, with no pattern related to the type of tea. The difference in a leaf's caffeine content is determined not by the type of tea, but by the plant cultivar, leaf age, and growing method. For example, nitrogen fertilizers raise caffeine in tea shoots by about 14% on average [5].

In the Cup: Why Black Tea Delivers a Little More

Technically, brewed black tea will have a bit more caffeine, but the reason lies not in the tea itself, but in how it is brewed.

Caffeine is a relatively hard-to-extract compound: it needs high temperature and time to pass into the infusion. Black tea is traditionally brewed with near-boiling water (95–100 °C), while green and white teas use cooler water (70–85 °C) and often shorter times. So from a leaf with the same caffeine content, black tea releases more into the cup.

This is supported by a recent study [4] that measured caffeine by HPLC in tea infusions. The brewing method proved to be the most powerful factor: in one and the same tea, caffeine rose several times over with longer steeping. For example, in yellow tea it climbed from about 13.8 to 53 mg/200 ml with just 10 minutes of brewing. Leaf fraction matters just as much: in the same study, black tea in cup-sized bags with fine cut yielded 39 mg/200 ml versus 24 mg for whole leaf. In other words, the same tea, brewed longer and in a finer cut, delivers several times more caffeine.

Where Caffeine Peaks: Matcha and Powdered Teas

You get the most caffeine not from black tea, but from matcha and any other powdered tea. With all ordinary teas we drink only the infusion - whatever managed to extract into the water - while we throw away the leaf itself. Matcha, on the other hand, we drink whole: the entire leaf, ground into powder, enters the body. Which means all the caffeine it contains does too.

One serving of matcha (usually about 2 g of powder) delivers around 60 mg of caffeine because it is 100% leaf, not an extract from it. It's important to understand: if you compare grams of dry leaf, matcha has no abnormally high caffeine - the whole secret is in the way it is consumed. The same principle would work with powder made from black tea leaf.

The Takeaway

• In the dry leaf, caffeine barely depends on the type of tea. For the same cultivar and region, the difference is minimal and statistically insignificant [1, 2].
• In the infusion, black tea usually delivers slightly more caffeine; the reason is the brewing method (temperature, time, leaf fraction), not the type of tea [4].
• Caffeine is highest in matcha and powdered teas, because you drink the whole leaf, not just the extract.
• Caffeine tends to be lowest in a short cold brew, where low temperature and a brief steep limit extraction. Our cold brew based on Nepalese tea, for instance, steeps for no more than 40 minutes in cold water.

Sources

[1] Chin J.M., Merves M.L., Goldberger B.A., Sampson-Cone A., Cone E.J. (2008). Caffeine Content of Brewed Teas. Journal of Analytical Toxicology, 32(8): 702–704. PubMed

[2] Carloni P., Tiano L., Padella L., Bacchetti T., Customu C., Kay A., Damiani E. (2013). Antioxidant activity of white, green and black tea obtained from the same tea cultivar. Food Research International, 53(2): 900–908. ScienceDirect

[3] Cloughley J.B. (1983). Factors influencing the caffeine content of black tea: Part 2 — the effect of production variables. Food Chemistry. ScienceDirect

[4] Ayakdaş G., Ağagündüz D. (2025). Determination of L-Theanine and Caffeine Contents in Tea Infusions with Different Fermentation Degrees and Brewing Conditions Using the Chromatographic Method. Foods, 14(13): 2313. PMC

[5] Qiao C., Xu B., Han Y., et al. (2018). Synthetic nitrogen fertilizers alter the soil chemistry, production and quality of tea. A meta-analysis. Agronomy for Sustainable Development, 38: 10. Springer