---
title: 'Theanine, amino acids and umami'
url: 'https://howtotea.me/science/chemistry/theanine'
markdown: 'https://howtotea.me/science/chemistry/theanine.md'
lang: en
date: '2026-10-25'
description: 'What theanine is and where tea umami comes from: shaded gyokuro, amino acids by type, why 50-60 °C water makes a soft cup, and what not to expect.'
---

# Theanine, amino acids and umami 茶氨酸

 Editors · October 25, 2026 · 9 min read

Theanine gives shaded Japanese teas their gentle sweetness and broth-like depth. It is not the only source of umami in the cup, and the reason to cool the water has nothing to do with heat destroying it.

 ![Dry gyokuro, dark green needles, and a cup of pale green tea](https://howtotea.me/images/c/o/v/e/r/cover-ca941bc9.webp) Illustration 

茶氨酸

Theanine and umami

chá ān suān

 What it is: a free amino acid of the tea plant

Discovered: 1949, Yajiro Sakato, Japan

Share of amino acids: 50-70% in new shoots

In dry tea: about 5-7 mg/g on average in green, white, oolong, black

Highest in: shaded teas: gyokuro, matcha

Almost absent: in pu-erh

Theanine is an amino acid that the tea plant makes in its roots and sends up into young shoots. Japanese chemist Yajiro Sakato described it in 1949, in a water extract of green tea. Theanine has the best reputation of any compound in tea, partly earned and partly marketing. It pays to know which part is which, because it affects the water you choose for each tea.

## Where theanine comes from

The plant builds theanine from glutamic acid and ethylamine, mostly in the roots, and moves it up through its vessels. In new shoots it makes up 50-70% of free amino acids. Other data, from Japanese samples, put it near 40%; the figure depends on cultivar, picking date and analytical method.

In light, an enzyme in the leaf splits theanine back apart, and the ethylamine goes into making catechins, the bitter, astringent [polyphenols](https://howtotea.me/science/chemistry/polyphenols). Sun, in other words, turns a soft leaf sharp.

Japanese growers worked this out before chemists did. More than 400 years ago they began covering tea gardens with reed mats and straw, first as frost protection. In the 1970s growers in Kyoto switched to black cloth. Today shading is done for flavor, not against frost.

## Shading: how gyokuro and matcha are made

[Gyokuro](https://howtotea.me/brewing/methods/sencha-gyokuro) is shaded for about 20 days from the start of first-flush growth, kabusecha for about 7 days before picking, and tencha (the raw material for matcha) for two to three weeks. For top quality, tencha is covered at 85-98% for at least 30 days.

In a Korean trial, 26 days under 95% shade raised theanine 3.7-fold, total free amino acids 3.4-fold and arginine 10.8-fold, while catechins (EGCG and EGC) fell. Sakato found up to 1.68% theanine in gyokuro. Caffeine in that trial doubled, so the softness of shaded tea comes from amino acids and a smaller share of catechins, not from less caffeine.

The mechanism is not settled. Japanese data show theanine rising in the picked shoots, while a Chinese trial on the Shuchazao cultivar found less in the leaf and more in the stem and root. Either way, shaded Japanese leaf brews reliably sweet and dense.

## Umami: what is in the cup

Theanine often gets the credit for tea's umami, but that is only partly true.

Theanine does bind the umami receptor T1R1+T1R3, at the same site as glutamate. But its taste threshold is high: 1,050-1,500 mg/L depending on the study, against 588 mg/L for glutamic acid. In a Japanese sensory test, 25 mM theanine sat right at the detection threshold, and 40% of participants tasted nothing. The threshold for monosodium glutamate is 0.87 mM, so theanine is a clearly weaker flavor compound. Paired with inosine monophosphate, an umami booster, it did produce 57% stronger umami.

A gyokuro experiment showed how the pieces fit. Researchers built a model solution of amino acids and acids at the concentrations of gyokuro liquor, and it tasted like dashi, Japanese broth. Remove glutamic acid and the umami collapsed. Remove theanine and the sweetness went. So glutamate supplies the broth, while theanine adds sweetness and reinforces glutamate, together with succinic and gallic acids and theogallin.

Chinese tea vocabulary describes the same thing differently. 鲜爽 (xiān shuǎng), bright freshness, is tied to amino acids. 醇厚 (chún hòu), fullness and body, is explained partly by theanine and γ-glutamyl peptides. To grade raw material, Chinese tea scientists use 酚氨比 (fēn ān bǐ), the polyphenol-to-amino-acid ratio: the lower it is, the fresher and softer the taste. Across four green tea cultivars, its correlation with the taste score was -0.955.

## Which teas are richest in amino acids

Shaded teas lead: [matcha](https://howtotea.me/brewing/methods/matcha) has more amino acids than gyokuro, and gyokuro more than sencha. Ceremonial matcha has more than 1.8 g of theanine per 100 g of dry matter; most industrial powdered teas have less. A test of 25 powdered teas in the US found that expensive samples held more theanine and arginine, even though cheap ones carried the same name, "matcha".

With ordinary teas it is less clear-cut. Here are the averages per gram of dry leaf across 37 samples:

| Type | Theanine, mg/g | Worth knowing |
|---|---|---|
| [Green](https://howtotea.me/teas/green) | 6.56 | literature range 3.07-21.18 |
| [White](https://howtotea.me/teas/white) | 6.26 | highest total free amino acids, about 25 mg/g |
| [Oolong](https://howtotea.me/teas/oolong) | 6.09 | range 0.90-12.37 within one sample |
| [Black](https://howtotea.me/teas/black) | 5.13 | theanine falls during withering |
| [Pu-erh](https://howtotea.me/teas/dark/puer) | not found, or 0.07-0.26 | flavor comes from other compounds |

You cannot tell green, white, oolong and black apart by theanine content, because the spread inside a type swamps the difference between types. And the deeper the oxidation, the fewer the amino acids, arginine above all.

Anji Baicha is a special case. It is a temperature-sensitive mutant whose shoots turn white if the average temperature at bud break stays at or below 20 °C. In those leaves the chloroplasts develop abnormally, protease activity rises, protein breaks down and free amino acids build up. Hence the cultivar's "fresh" taste.

## What this changes in the brew

Amino acids dissolve in water easily, while galloylated catechins and caffeine dissolve mostly in hot water. Both ways of brewing amino-acid-rich tea rely on this.

**Cool water and gyokuro.** In water near 0 °C, about 80% as much theanine reaches the liquor as in an 80 °C, 2-minute brew. For caffeine it is about 50%, and in ice water (0.5 °C) under 20%; for EGCG about 20%. That is why [cold brewing](https://howtotea.me/brewing/methods/cold-brew) gives a sweet, soft cup. Gyokuro can also be brewed warm: the Shizuoka prefecture guide calls for 50 °C for top grade and 60 °C for ordinary. Top-grade sencha is brewed at 70 °C, ordinary at 90 °C, and bancha and hojicha take boiling water.

Gyokuro, Shizuoka prefecture method

For three people, use 10 g of leaf. Cool boiled water in a [kyusu](https://howtotea.me/teaware/by-region/japan-and-korea/kyusu) to 50 °C (top grade) or 60 °C, pour about 20 ml into each of three cups, then pour the water from the cups over the leaf. The first steep runs 2 minutes 30 seconds at 50 °C (122 °F) or 2 minutes at 60 °C, the second about a third of that. Pour around the cups until the last drop, and drink at 35-40 °C.

**Time first.** In the first 2 minutes about half the leaf's theanine reaches the liquor, so steep time, more than anything, decides how much ends up in the cup. When sencha is brewed three times, its main amino acids come out in the first and second infusions, while EGCG and ECG barely dissolve at 50 °C. If the first infusion is made with cold water (5 °C, 10 minutes), it turns out the sweetest, and the third at 95 °C the bitterest. In a multi-infusion test of Bingdao pu-erh, infusions 3 through 7 tasted best, and after the seventh amino acids were 28.86% lower.

**Not because of theanine.** Hot water does not destroy theanine: in the British measurements, water at about 80 °C did not lower the theanine extracted, though that study has no data for 100 °C. Water is cooled to pull less bitterness. For pu-erh and black tea, where theanine is low, cooling the water for amino acids makes no sense, since their flavor comes from other compounds. [Water for tea](https://howtotea.me/brewing/basics/water), and how temperature and time drive the [extraction](https://howtotea.me/science/water-and-extraction/extraction) of everything else, are covered separately.

Adding 12 ml of milk to 200 ml does not change the amount of theanine, while 50 ml noticeably lowers the measurable free theanine.

## Theanine, caffeine and what not to promise

Theanine and caffeine are often studied together. In a double-blind trial by Haskell and colleagues, after 250 mg of theanine with 150 mg of [caffeine](https://howtotea.me/science/chemistry/caffeine) participants reacted faster on simple reaction and numeric working-memory tasks and verified sentences more accurately; neither compound did this alone. In smaller trials (97 mg theanine with 40 mg caffeine) task switching improved, but alertness and intersensory attention did not.

Now compare those doses with a cup. In 200 ml of British teabag tea, researchers found 7.9 mg of theanine in green, 11.5 mg in white and 24.2 mg in black.[1](#fn:1) That is an order of magnitude below the doses in experiments. And in 2011 the European Food Safety Authority (EFSA) rejected the claimed benefits: a link between tea theanine and better cognitive function, relief of psychological stress or normal sleep was not established.[2](#fn:2)

What is well established is that theanine shapes flavor. Its effect on attention remains unproven.

## Myths in brief

- "Tea umami is theanine." No. Most of it comes from glutamate; theanine boosts it and adds sweetness.
- "Green tea always has the most theanine." In teabags black came out ahead: at a 2-minute steep it held 24.2 mg against 7.9 mg for green.
- "Pu-erh is rich in theanine." It has none, or almost none.

## Common questions

Does boiling water destroy theanine?

No. In measurements by British researchers, water at about 80 °C did not reduce the theanine in the liquor; that study has no data for 100 °C. Water for gyokuro is cooled for another reason: cooler water pulls fewer bitter catechins and less caffeine into the cup.

Which tea has the most theanine?

Shaded Japanese teas: gyokuro and matcha. Among other types the averages per gram of dry leaf are close, and the spread within one type is huge, so calling a tea green or black tells you nothing about its theanine. Pu-erh has almost none.

Is one cup of tea enough for the theanine effects seen in studies?

Probably not. Studies used 97-250 mg of theanine, while a 200 ml cup of British tea had 7.9-24.2 mg. In 2011 the European Food Safety Authority also found the health claims for tea theanine unsubstantiated.

Notes

1. Keenan E. K. et al. How much theanine in a cup of tea? Effects of tea type and method of preparation. Food Chemistry. 2011. 125:588-594. [doi:10.1016/j.foodchem.2010.08.071](https://doi.org/10.1016/j.foodchem.2010.08.071). Water at about 80 °C, 2-minute steep. [↩](#fnref1:1)
2. EFSA Panel on Dietetic Products, Nutrition and Allergies. Scientific Opinion on the substantiation of health claims related to L-theanine from Camellia sinensis. EFSA Journal. 2011. 9(6):2238. [doi:10.2903/j.efsa.2011.2238](https://doi.org/10.2903/j.efsa.2011.2238). [↩](#fnref1:2)

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