lǜchá

Green tea is not a single beverage but an entire family united by a common technological logic: stop oxidation at the very beginning and preserve the “greenness” of the leaf. The key to this family is the operation shā qīng (杀青), “killing the green,” and the heating method by which it is performed.

What makes tea green

All green teas — from flat lóng jǐng (龙井) to rolled zhū chá (珠茶) — pass through the same framework:

鲜叶 (摊放) → 杀青 → 揉捻 (做形) → 干燥

That is: fresh leaf, light spreading-withering, kill-green, rolling-shaping, and drying. The differences between dozens of famous varieties lie not in a change of this framework, but in the nuances of two of its links — shā qīng (type of heating) and zuò xíng (做形, giving shape).

The fundamental difference between the green class and the red class (black according to Western nomenclature) lies in when and what the enzyme does. In red tea, rolling (róu niǎn, 揉捻) initiates oxidation. In green tea, everything is reversed: high-temperature shā qīng is performed before oxidation has a chance to begin, and the enzyme is inactivated.

Chemistry: why the leaf stays green

The central figure here is polyphenol oxidase (多酚氧化酶, PPO). It is precisely this enzyme that, in the presence of oxygen, oxidizes catechins, turning a green leaf into a red one. The task of shā qīng is to rapidly raise the leaf temperature and inactivate PPO before the start of oxidation. Oxidation simply does not start.

A consequence is the preservation of a whole set of substances that form the profile of green tea:

• 茶多酚 (tea polyphenols, catechins, including EGCG) — responsible for bitterness, astringency, and the overall structure of the infusion;
• 叶绿素 (chlorophyll) — the green color of the leaf and infusion;
• 茶氨酸 (theanine) — umami and sweetness;
• vitamin C.

The flavor balance of green tea rests on three axes: xiān shuǎng (鲜爽, fresh liveliness from theanine and amino acids — higher in early and shaded raw material), kǔ sè (苦涩, bitterness-astringency from catechins — higher in summer harvests), and huí gān (回甘, returning sweetness).

Hence the main characteristic of storage. Green tea does not “age” nobly, unlike pǔ ěr or white tea. It is precisely the fresh leaf that is valued — xīn chá (新茶), harvests of míng qián (明前, before Qingming) and yǔ qián (雨前, before 谷雨, Grain Rain). It should be stored in cold conditions, without access to light and extraneous odors.

Withering and drying: the frame around kill-green

Before reaching shā qīng, the leaf undergoes 摊放 (tān fàng) — spreading for a light loss of moisture and accumulation of aroma. This is softer and shorter than the deep withering (wěi diāo, 萎凋) of red tea: the task is not to allow oxidation to proceed, but only to prepare the leaf.

The chain is closed by 干燥 (drying) — chǎo gān (炒干, pan-roasting), hōng gān (烘干, oven-drying), or shài gān (晒干, sun-drying). Drying fixes the shape and completes the aroma: pan-roasting develops the chestnut note lì xiāng (栗香) and “wok heat” guō qì (锅气), while oven-drying yields a clean floral-herbaceous qīng xiāng (清香).

The 杀青 axis: five heating modes

It is the method of performing shā qīng that determines the aromatic “accent” of the tea. This is the main classification axis of the green class.

炒青 (chǎo qīng) — pan-fired. The leaf is heated in a red-hot wok or drum. It gives a characteristic guō qì (锅气) and chestnut lì xiāng. This is the “fried” school, to which most famous flat and rolled varieties belong.

烘青 (hōng qīng) — oven-baked. Heating by hot air. The aroma is purer and lighter — qīng xiāng (清香). It is precisely hōng qīng lǜ chá that serves as the base for jasmine and other scented teas: the loose oven-baked leaf structure readily accepts floral aroma during xūn zhì (窨制).

晒青 (shài qīng) — solar. Fixation and drying proceed under the sun. This mode gives shài qīng máo chá (晒青毛茶) — the raw material from which sheng pu-erh (pǔ ěr shēng) is made. That is, solar green is a bridge to a completely different class.

蒸青 (zhēng qīng) — steam. The leaf is treated with steam. It preserves a particularly bright greenness and gives a seaweed note hǎi tái xiāng (海苔香, “seaweed”). In China, ēn shī yù lù (恩施玉露) belongs to this school; this same mode forms the basis of Japanese sencha (煎茶).

半烘炒 (bàn hōng chǎo) — combined. A combination of oven and wok heating, giving an intermediate profile between pure qīng xiāng and pronounced guō qì.

The shape axis: what 做形 does

If shā qīng sets the aroma, then zuò xíng (做形) sets the appearance — the second load-bearing axis of the class. Several examples of techniques and their results:

• huī guō (辉锅) → flat shape (扁), as in lóng jǐng;
• cuō tuán (搓团) → spiral (螺), as in bì luó chūn (碧螺春);
• lǐ tiáo (理条) → needle (针);
• lā lǎo huǒ (拉老火) → flake-platelet (片), as in guā piàn (瓜片).

For some particularly tender varieties — for example, tài píng hóu kuí (太平猴魁) — shaping is minimal, with the leaf preserved almost in its natural state.

The final palette of green tea shapes: flat / spiral / needle-like / orchid-like (兰花) / flake / “flower” (朵) / round pellet-pearl (颗粒珠) / “eyebrow” (眉).

Links to other classes

Green tea is a nodal class of Chinese tea taxonomy, and many neighboring families grow directly out of it:

• 晒青毛茶 (solar green) → raw material for sheng pu-erh;
• 烘青绿茶 (oven-baked green) → base for jasmine and other scented teas via xūn zhì;
• 蒸青 (steam) → technological bridge to Japanese green tea;
• 黄茶 (yellow tea) = green plus an additional step mèn huáng (闷黄, “smothering to yellowness”).

Understanding these connections helps one see that the boundary between classes runs not along the plant, but along the technology.

How to distinguish in practice

To “read” a green tea, it is enough to keep the formula in mind: aroma = variety (品种) × 杀青 × harvest season × terroir.

• If a roasted, chestnut tone with “wok heat” is audible in the dry leaf and infusion — you have chǎo qīng before you.
• A pure, light herbaceous-floral qīng xiāng without burnt notes points to hōng qīng (and often to a tea base for scenting).
• A bright, almost marine algae note is a sign of zhēng qīng, the steam school.
• A rough, “solar” tone in the dry raw material may speak of shài qīng — a potential ancestor of pu-erh.

Freshness is assessed by the liveliness of the green color of the infusion and the expression of xiān shuǎng: a dull color and a flat, “stewed” taste are a sign that the tea has lost its youth. Remember: for the green class, age is a drawback, not a virtue.

Related: shape axes (做形), aroma wheel, Japanese green tea, yellow tea, and pu-erh.