The caffeine content of tea is not determined by the type of leaf alone. Here, we will introduce how it can be controlled through cultivation and processing, and most importantly, through the brewing methods you can practice at home.
The Influence of Cultivation and Processing: Harvest Time and Production Methods
The cultivation and processing steps that define a tea's flavor and aroma also affect its caffeine levels. This information is based less on national data and more on the scientific knowledge and principles from the front lines of tea production.
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Influence of Harvest Time: "Ichibancha" (First Flush) is Rich in Caffeine For the tea plant, caffeine acts as a natural defense mechanism to protect new buds from insects. Therefore, the energetic young buds of the first harvest ("Ichibancha") contain the most caffeine. Levels tend to decrease in the tougher, more mature leaves of later harvests ("Nibancha," "Bancha," etc.). This is why higher-grade Sencha is often said to have more caffeine.
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Influence of Processing (1): The "Steaming" of Sencha While Sencha can be classified as lightly steamed (Asamushi), normally steamed (Chumushi), or deeply steamed (Fukamushi), the steaming time itself does not change the caffeine content of the tea leaves. However, because the leaf structure of deep-steamed tea is finer, its components infuse more easily into water. As a result, when brewed for the same amount of time, deep-steamed tea tends to yield more caffeine.
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Influence of Processing (2): "Roasting" and "Blending" "Hojicha" and "Genmaicha" are popular for their low caffeine content. The reason lies in their processing.
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Hojicha (Roasted Green Tea): During the high-temperature roasting process, some of the caffeine in the tea leaves turns to vapor (sublimates) and is reduced.
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Genmaicha (Green Tea with Roasted Rice): By blending green tea with roasted brown rice, the relative amount of tea leaves in a serving is lower, which in turn reduces the caffeine content per cup.
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The Art of Brewing: How Temperature and Time Change Extraction
Brewing does not remove caffeine from tea, but it changes how much is extracted into the cup. Water temperature, steeping time, the amount of tea used, and water volume all affect the result.
Hotter water generally extracts caffeine more readily. It can also bring forward more bitterness and astringency, giving the cup a sharper profile.
Cooler water generally extracts caffeine more slowly. It can also bring forward a softer balance of sweetness and umami. Cold-brewed tea still contains caffeine and should not be considered caffeine-free.
Lower-temperature brewing is often used for gyokuro to highlight its rich umami and tender sweetness. The amount of caffeine in the finished cup still depends on the tea, the quantity used, and the complete brewing method.
Compare caffeine reference values for sencha, genmaicha, hojicha, gyokuro, and matcha →
We believe that by understanding the characteristics of each tea and by adjusting your brewing method, you can freely enjoy tea in a way that suits your body and mood. We sincerely hope this guide helps you further enjoy the profound world of Japanese tea.
