Sensory Evaluation of Green Tea: What Tasters Check

Professional green tea tasting scores five things: the dry leaf appearance, the liquor colour, the aroma, the taste and the wet leaf. Each is scored separately and the total is weighted, and the weighting differs between competitions. The method exists to make tasting reproducible rather than to describe the experience of drinking.

A drinker can use the same five categories informally and it will improve their buying, because the categories catch different faults. A tea can look excellent and taste flat, or look ordinary and taste superb.

The five categories

The dry leaf is assessed before brewing and it tells you about the picking and the firing. An even, bright leaf with visible tips is a high grade; a dull, mixed leaf is not.

The liquor is assessed in a white cup against a white background, because colour and clarity are hard to judge otherwise. A bright, clear liquor is a good sign; a cloudy or dull one is not.

The aroma is assessed three times: the dry leaf, the wet leaf and the empty cup. The three should agree, and a tea whose dry leaf smells strongly and whose cup smells of nothing has been flavoured or is stale.

The taste is the largest weight and the hardest to score consistently. Sweetness, astringency, body and finish are judged separately, and a tea can score well on three and badly on the fourth.

The wet leaf, which drinkers ignore}

The wet leaf is the most informative category and the least used by drinkers. After brewing, the leaf shows the picking standard, the firing and the tenderness, and it cannot be faked.

A high-grade green tea has a wet leaf of even size, bright colour and soft texture. A coarse tea has larger, tougher leaves and visible stems. A badly fired tea has leaves with scorched edges or a dull, greyish colour.

A tea that claims a bud-only pick but shows open leaves in the wet leaf is mislabelled, and the wet leaf is the evidence. That check costs nothing and settles a claim the dry leaf cannot.

How to run the assessment at home

Use three grams in 150 millilitres at 80 Celsius for two minutes, in a white cup or a glass. That is a standard infusion and it makes two teas comparable.

Look at the liquor before smelling it, then smell the wet leaf, then taste. Note each separately and write a line. The written note is what makes the exercise cumulative rather than a series of impressions.

Compare two teas at a time rather than one. A single tea can only be judged against memory, and two teas can be judged against each other.

The method is not a substitute for enjoyment and it is a way of paying attention. A drinker who scores a tea once will notice more of it the next time.

• Five categories: dry leaf, liquor, aroma, taste, wet leaf.
• Taste carries the largest weight in most scorings.
• Aroma should be checked dry, wet and in the empty cup.
• The wet leaf reveals the picking and cannot be faked.
• Use three grams in 150 ml at 80 Celsius for two minutes.
• Compare two teas rather than judging one from memory.

What the method cannot do

It cannot tell you whether you like the tea. A high score is a judgement about technique and consistency, not about preference, and a drinker can prefer a lower-scoring tea without being wrong.

It also cannot detect freshness reliably. A stale tea can score well on appearance and poorly on aroma, and the scoring system does not weight age.

And it cannot compare across styles. A steamed tea and a pan-fired tea are scored on different expectations, and a competition separates them for that reason.

The method is a tool for attention rather than a verdict, and using it that way is more useful than treating a score as a ranking.

Why the wet leaf settles arguments

The wet leaf is the only part of the assessment that shows what was picked rather than what was done to it. A claimed bud-only tea that shows open leaves has been mislabelled, and the evidence is in the vessel.

It also shows the firing. A leaf with scorched edges was fired too hot; a leaf that is uniformly dull grey was dried too slowly or stored too long.

And it shows the tenderness. A high-grade leaf is soft enough to press flat between the fingers; a coarse one is stiff and resists.

That is a lot of information from a part of the tea that most drinkers throw away, and it is the reason professional tasting weights the category at all.

• The wet leaf shows the picking standard.
• Open leaves in a claimed bud tea mean a mislabel.
• Scorched edges mean the firing was too hot.
• A uniform dull grey means slow drying or long storage.
• Tenderness shows in how the leaf presses.
• It is the category drinkers most often ignore.

How the score is used in practice

Competitions use the five categories to rank teas within a style, and the rankings are published. A drinker can use them as a starting point for what a good example of a style tastes like.

The scores are not comparable across styles, and a gold medal for a pan-fired tea says nothing about a steamed one. That is why the competitions separate them.

A drinker should also note that a competition tea is chosen for its peak, not for its keeping. A medal-winning tea is often one to drink now rather than to store.

Used that way, the scoring system is a useful guide to style rather than a ranking of teas, which is what it was designed to be.

What the aroma categories mean

Green tea aroma divides into three families that track the firing method. Pan-fired teas smell of chestnut, toasted grain and sometimes a little smoke. Baked teas smell softer, of cooked vegetable and honey. Steamed teas smell marine, of seaweed and fresh grass.

A taster scores the aroma on type, intensity and purity. Type means whether it belongs to its family; intensity means how strong it is; purity means whether there is anything foreign in it, such as smoke in a steamed tea or a cardboard note in anything.

Purity is the most heavily penalised and the easiest to detect. A tea that smells of its family plus something else has a fault, and the something else is usually storage or firing.

A drinker can apply the same three-part test informally and it will catch most of what is wrong with a tea.

• Pan-fired: chestnut, toasted grain, a little smoke.
• Baked: cooked vegetable, honey, softer.
• Steamed: seaweed, fresh grass, marine.
• Score type, intensity and purity separately.
• Purity faults are the most penalised and the easiest to spot.
• A foreign note usually means storage or firing.

A drinker who scores a tea once will notice more of the next one, which is the only lasting benefit of the method and a sufficient reason to try it.

That is the whole of the sensory method, and it is a discipline rather than a verdict.

Why taste carries the most weight

Taste is weighted highest because it is the category least amenable to disguise. Appearance can be improved by sorting, aroma can be enhanced by blending or flavouring, and the wet leaf can be sorted after firing. Taste follows the leaf and the process.

Within taste, sweetness and astringency are the pair that matters. A green tea should be sweet with a clean astringency that fades; one that is only astringent is either a coarse leaf or an over-steeped cup.

The finish is the last part of the category and the most revealing. A good tea leaves a sweetness that persists for half a minute; a poor one leaves nothing or a dry sensation.

A drinker who judges only the front of the cup will rank teas differently from a taster who waits. The wait is the technique, and it costs nothing.

That is why the professional method is worth borrowing even informally. It is a set of habits for paying attention in the right order.

That is the whole of the sensory method, and it is a way of paying attention rather than a way of ranking teas against each other.

Frequently asked questions