No. 028 — The Bitterness of Tea

Sometimes, just a few extra seconds of steeping is enough to change the face of a cup. Tea that seemed fresh, vegetal, or delicate becomes firmer, more intense, sometimes downright bitter. Conversely, some leaves withstand long steeps without producing that biting sensation that many drinkers seek to avoid.

Bitterness is therefore one of the most familiar perceptions of tea, but also one of the most misunderstood. It is often confused with astringency, attributed indiscriminately to "tannins," or considered proof that a tea is bad. These shortcuts are convenient, but they poorly describe what really happens in a cup.

Tea is a chemically complex infusion. Its leaves contain many molecules capable of influencing our perception: caffeine, catechins, flavonoids, amino acids, sugars, aromatic compounds, and products resulting from the processing carried out during manufacturing. When water meets the leaf, some of these substances gradually pass into the liquor. Temperature, time, the amount of leaves, particle size, and even the composition of the water alter the final balance.

I. What Is Bitterness?

Bitterness belongs to the basic flavors recognized by our taste system. It is perceived thanks to specialized receptors located notably on the tongue. When a molecule capable of stimulating these receptors comes into contact with them, the brain interprets the signal as a bitter sensation.

In tea, several families of compounds can contribute to this perception. Caffeine is known for its bitter taste. Certain catechins also contribute to bitterness, with an intensity that varies according to their structure, their concentration, and the interactions they have with the other constituents of the liquor.

This nuance is essential. The words we use to describe tea often give the impression that a single molecule would be responsible for a unique sensation. In reality, the perception of an infusion is the result of a balance. Two teas containing comparable amounts of the same compound can give different impressions because their overall composition, their manufacturing, and their aromatic profile are not identical.

II. Bitterness and Astringency: Two Different Sensations

This is probably the most frequent confusion when talking about tasting.

Bitterness is a flavor. Astringency is primarily a tactile sensation. It gives the impression that the mouth tightens, that the mucous membranes become drier or slightly rough. You can experience one without strongly experiencing the other.

A heavily steeped green tea can be both bitter and astringent. Yet, these two perceptions do not necessarily appear at the same time. Bitterness can quickly manifest on the tongue, while astringency sometimes develops gradually and leaves a sensation of dryness after swallowing the liquor.

This separation is not merely theoretical. It allows you to better diagnose an infusion. A cup that is too bitter may require a lower temperature or a reduction in time. A cup that is mainly astringent may, on the other hand, be linked to the nature of the tea itself, its dosage, or an over-extraction of certain phenolic compounds.

III. Why Does Tea Contain Bitter Molecules?

The leaves of Camellia sinensis are not designed for our cup. They belong first to a living plant. The molecules we find in the infusion play different biological roles for the tea plant.

Caffeine and polyphenols are therefore not artificially added to create a flavor. They are naturally present in the leaf, in varying proportions according to the tea plant variety, the age of the leaves, the growing conditions, the season, the light received, and the transformations carried out after harvest.

The producer's work then greatly changes the way these constituents will express themselves in the cup. Withering, heat-fixing, rolling, oxidation, drying, roasting, or aging transform the leaf and change its chemical and sensory profile.

This is one of the reasons why a Japanese green tea, a black tea, an oolong, or a dark tea can present very different forms of bitterness even though they all come from the same botanical genus.

IV. Caffeine: Part of the Story

Caffeine naturally has a bitter flavor. It therefore participates in the flavor profile of tea. This does not mean, however, that a tea containing more caffeine will automatically be perceived as more bitter.

Tasting is a system of balances. Amino acids can bring sweetness or umami, sugars contribute to roundness, aromatic compounds change our overall interpretation, while polyphenols add their own contribution.

Two infusions can thus present different concentrations of caffeine but a perception of bitterness that does not follow exactly the same hierarchy.

This is why you should avoid an overly simple rule like "more caffeine = more bitter." Caffeine counts, but it does not decide alone.

V. The Role of Catechins

Catechins constitute an important family of polyphenols present in tea leaves, especially in lightly oxidized teas. They participate in the flavor structure of the infusion and can contribute to both bitterness and astringency.

However, studies on the taste of tea show that not all catechins have exactly the same effect. Some are more associated with bitterness, others with astringency, and their perception varies according to the concentration and interactions with the other substances present in the cup.

VI. Why Does a Too-Long Infusion Often Become More Bitter?

When leaves are immersed in water, their constituents do not all pass instantly into the liquor. Extraction takes place gradually.

A short infusion can favor certain rapidly soluble molecules and produce a light, aromatic, or sweet cup. By prolonging the contact, more compounds are extracted. The concentration of molecules contributing to bitterness and astringency can then increase.

This explains why greatly exceeding the recommended time sometimes radically transforms a tea. The infusion is not simply "stronger": its sensory balance changes.

This evolution is particularly visible with certain green teas or broken leaves, whose contact surface with water facilitates a rapid extraction.

VII. Water Temperature

Warmer water generally accelerates the extraction of many substances present in the leaves. It can therefore accentuate the intensity of an infusion and favor the expression of bitterness when the tea is sensitive to high temperatures.

This is one of the reasons why many green teas are prepared with water that is significantly less hot than that used for a robust black tea.

But again, a universal rule would be misleading. Not all green teas react the same way, and not all black teas require water close to boiling. Leaf size, manufacturing method, and the desired style also count.

VIII. Dosage Changes Everything

A large amount of leaves in a small volume of water naturally increases the concentration of the extracted substances. At identical time and temperature, a highly dosed infusion can therefore become more intense and reveal more bitterness.

Yet, methods using a lot of leaves do not necessarily produce unpleasant cups. In gongfu-style preparations, for example, the high dosage is compensated by very short infusions.

This illustrates a fundamental principle: time, temperature, and the amount of leaves must always be considered together.

Changing a single parameter can be enough to restore the balance.

IX. Broken Leaves Extract Faster

A whole leaf and a leaf reduced to small fragments do not offer the same contact surface with water. Fine particles generally allow for faster extraction.

This is why some tea bags or certain black teas with very broken leaves can produce a powerful cup in a short time. If the infusion is prolonged, bitterness and astringency can quickly dominate.

Conversely, large whole and rolled leaves may require more time to open and gradually release their constituents.

X. Is Bitterness Always a Flaw?

No.

This is probably the most important point of this Tsuru.

A slight bitterness can bring depth, tension, and relief. It can balance a vegetal sweetness, a pronounced umami, or very rich aromatic notes.

In certain tea styles, it is part of the desired personality. In some young pu-erhs, for example, a distinct bitterness can quickly evolve in the mouth and leave a sweeter impression after a few seconds. In other teas, a hint of bitterness prevents the flavor profile from becoming flat.

The problem begins when bitterness overwhelms everything else: no more perceptible aroma, no more sweetness, no more finesse, only an aggressive and persistent sensation.

It is therefore necessary to distinguish structuring bitterness and dominant bitterness.

XI. Why Are Some People More Sensitive?

Taste perception varies from one individual to another. We do not all have exactly the same sensitivity to bitter compounds.

Habit also plays a role. A person discovering green tea may find an infusion very bitter that an experienced connoisseur will simply judge as lively or structured. As we taste, we learn to distinguish the nuances behind this sensation.

This does not mean that you should learn to love an unpleasant cup. Tasting is not a contest of endurance. On the contrary, it consists in understanding what you feel and adjusting the preparation according to your taste.

XII. How to Correct a Tea That Is Too Bitter?

When your tea becomes too bitter, change one parameter at a time. This is the best way to understand the origin of the problem.

Start by slightly reducing the steeping time. If that is not enough, lower the temperature by a few degrees. You can also reduce the amount of leaves or slightly increase the volume of water.

On a delicate green tea, a relatively small difference can completely transform the cup.

It is also useful to check the quality of the water. Very mineralized water or water with a strong taste can change the overall perception of the infusion and mask certain subtleties.

XIII. Cold Infusion: Another Path

Cold infusion constitutes a particularly interesting experience when a tea seems difficult to master. The principle consists in letting the leaves steep for several hours in cold water, generally in the refrigerator.

The extraction kinetics are therefore not the same as with hot water. The resulting cup can seem sweeter and less aggressive, with a different aromatic profile.

This is not a way to "fix" all teas, but a preparation method in its own right that shows how much temperature influences the result.

XIV. A Bitterness That Disappears Can Be Interesting

Not all bitternesses behave the same way.

Some appear immediately and linger in the mouth. Others are brief: they emerge, then disappear to make room for a sweeter, fresher, or more aromatic sensation.

This evolution is particularly interesting when tasting a tea over several successive infusions. A first cup may seem firm, while the following ones reveal more sweetness or depth.

Time then becomes a dimension of tasting.

XV. Learning to Taste Bitterness

Rather than only asking yourself if a tea is bitter, try to qualify this bitterness.

Is it light or intense? Does it arrive immediately? Does it linger? Is it accompanied by astringency? Does it mask the aromas or give them relief? Does a sweetness appear afterwards?

These questions profoundly change the tasting.

You are no longer simply trying to classify the tea into two categories — good or bad — but to understand its structure.

XVI. What Bitterness Teaches Us About Tea

Bitterness reveals something essential: preparing tea is not simply putting leaves in water.

Every infusion is an extraction. The result depends on the leaf and how we choose to prepare it.

When a tea tastes too bitter, the first instinct should therefore be observation rather than judgment. Was it steeped for too long? Was the water too hot? Was too much tea used? Are the leaves small and quick to steep? Is this intensity part of the tea's style?

By gradually answering these questions, we gain a better understanding of the raw material. And we often discover that a tea previously judged difficult can become remarkable after a few adjustments.

Summary

Bitterness in tea is a genuine flavor, distinct from astringency. Several natural compounds in the leaf can contribute to it, notably caffeine and certain catechins.

Its intensity depends, however, on a much broader set of factors: the tea plant variety, the maturity of the leaves, processing, particle size, dosage, water temperature, and steeping time.

A slight bitterness is not necessarily a flaw. It can give the cup structure, create contrast, and contribute to the complexity of a great tea. It becomes problematic when it dominates to the point of obscuring everything else.

Understanding bitterness therefore allows us to prepare our tea better, but also to enjoy it more fully.