# Tea, the long way round — processing and cultivar field notes

Notes I keep for the tea-bar staff, past the beginner's "green / black / oolong"
sketch. Two ideas do most of the work: **how far the leaf is oxidised, and
whether that change is enzymatic or microbial**, and **which cultivar of
*Camellia sinensis* the leaf came off**. Everything else — colour, aroma, the
water you brew it with — falls out of those two.

## The six classes, by what is done to the leaf

Chinese tea tradition sorts true tea into **six classes**, and the cleanest way
to hold them is as a ladder of processing, not just a row of colours. All six are
the same species; the maker's choices make the tea.

1. **White** — the least handled. The leaf is withered and dried, and that is
   essentially it: no deliberate kill-green, no rolling, just a little incidental
   oxidation creeping in during the long wither. Silver-needle (buds only) and
   white-peony (bud plus leaves) are the classics. Delicate, hay-sweet, softly
   floral.
2. **Green** — oxidation stopped early and hard. Soon after picking, the leaf is
   "fixed" (kill-green) with heat to denature its polyphenol oxidase (PPO), the
   enzyme that would otherwise brown it. **How** you fix it splits the world's
   greens in two: China mostly **pan-fires** (Longjing, "Dragon Well," wok-fired
   flat in Hangzhou), while Japan almost entirely **steams** (sencha, gyokuro),
   which locks in a greener, more marine, umami cup. Fresh, grassy, vegetal.
3. **Yellow** — the rare one. Made like a green, but with an added slow, damp
   "sealing" step (men huang, "sealing yellow"), where the warm, just-fixed leaf
   rests under cover and mellows through gentle non-enzymatic yellowing. It rounds
   green tea's grassy edge into something softer and sweeter. Junshan Yinzhen and
   Meng Ding Huangya are the famous names; the process is labour-heavy and the
   class is nearly a museum piece.
4. **Oolong** — the partial-oxidation middle, and the widest class of all. The
   leaf is withered, then bruised (shaken or tumbled so the edges break and
   oxidise while the centres stay green), oxidised anywhere from about 10% to 80%,
   then fixed and rolled. Light oolongs (jade Tie Guan Yin) sit near green and
   taste floral and creamy; dark oolongs approach black and taste roasted and
   stone-fruity.
5. **Black** (called "red tea," hongcha, in China, after the colour of the liquor)
   — **fully** oxidised. Withered, rolled to rupture every cell, oxidised right
   through, then dried. Dark, brisk, malty; the backbone of most Western breakfast
   blends.
6. **Dark** (heicha, "dark tea") — **post-fermented**. After a kill-green, the leaf
   is deliberately aged under microbial action, a genuinely different process from
   black tea's enzymatic oxidation: bacteria and fungi, not the leaf's own
   enzymes, do the work over months to years. **Pu-erh is the famous dark tea.**
   Earthy, smooth, mellow, and often pressed into cakes.

The nuance beginners miss: **black tea and dark tea are not the same thing.**
Black tea is oxidised by the leaf's own enzymes in a matter of hours; dark tea is
fermented by microbes over months or years. Two different chemistries, two
different words that English unhelpfully blurs.

## Sheng vs. shou pu-erh — worth its own paragraph

Pu-erh, from Yunnan, is the dark tea people actually buy, and it splits in two:

- **Sheng ("raw") pu-erh** is kill-greened, sun-dried into loose "maocha,"
  pressed into cakes, and then **left to age slowly** — years to decades — through
  gradual microbial and oxidative maturation. Young sheng is bright, bitter,
  almost green-tasting and can be punchy; well-aged sheng turns deep, sweet, and
  mellow. It is the one that, like wine, is laid down to improve.
- **Shou ("ripe") pu-erh** is the modern shortcut. Developed in **1973** (the
  Kunming and Menghai tea factories) to imitate decades of ageing in a matter of
  weeks, it uses **wo dui, "wet piling"**: the leaf is heaped damp and warm for
  roughly **45-60 days** so microbes force-ferment it. The result is dark, smooth,
  earthy, low in bitterness, and drinkable immediately — no waiting.

Same leaf, same province; one is aged for years, the other force-fermented in a
pile. That is the whole distinction, and it is the single most useful thing to
know about pu-erh.

## Cultivars — the grape-variety layer

Under the six classes sits the cultivar: a specific bred variety of the plant.
Two botanical varieties anchor everything — *Camellia sinensis* var. *sinensis*
(small-leaf, cold-hardy, the China highlands) and var. *assamica* (big-leaf,
tropical, malty, the base of Assam and most pu-erh) — and beneath them, hundreds
of named cultivars.

A few worth knowing by name:

- **Yabukita** — the single cultivar behind roughly **70% of all Japanese tea**.
  Selected in Shizuoka and registered as an official cultivar in **1953**, its
  hardiness and balanced, umami-forward cup made it the near-monoculture backbone
  of Japanese sencha. When a Japanese green tastes "classic," it is usually
  Yabukita.
- **Da Hong Pao ("Big Red Robe")** — the flagship **Wuyi rock oolong (yancha)**,
  from the cliffs of the Wuyi Mountains in Fujian. Rock oolongs are prized for
  **yan yun, "rock rhyme"** — a mineral resonance the cliff terroir lends the cup.
  A handful of ancient "mother bushes" on the Wuyi cliffs are treated as national
  treasures; almost all Da Hong Pao sold today is a blend of related Wuyi
  cultivars such as **Rou Gui** (spicy, cinnamon bite) and **Shui Xian** (thick,
  mossy, creamy body), tuned to the classic profile.
- **Darjeeling flushes** — in the Himalayan foothills of West Bengal the *same
  bushes* give very different teas by season. The **first flush** (spring,
  March-April) is light, greenish, floral, and briskly astringent — **no
  muscatel**. The **second flush** (early summer, May-June) is the prized one:
  fuller, amber, carrying the famous **muscatel** note, a sweet, grape-like,
  slightly spicy character. That muscatel is partly a gift of the jassid
  leafhopper, whose nibbling on the warm-season leaf triggers the muscat-grape
  aromatics; estates now time the second-flush pluck to the insect.

## Shading, L-theanine, and umami — why gyokuro and matcha taste of broth

The most striking flavour trick in tea is **shading**. For roughly **20-30 days
before harvest**, the bushes destined for **gyokuro** and for **tencha** (the leaf
later stone-ground into **matcha**) are covered to block about 90% of the
sunlight. Starved of light, the leaf rewrites its own chemistry:

- **L-theanine** — the amino acid nearly unique to the tea plant, the one behind
  tea's calm-alert feeling — is normally converted into catechins in sunlight.
  Shade halts that conversion, so **L-theanine accumulates** in the leaf. Because
  L-theanine itself tastes sweet and brothy, the shaded cup reads as deep
  **umami** rather than grass.
- **Catechins** (the astringent antioxidants, EGCG among them) **fall**, since
  less L-theanine is being turned into them — so shaded teas are markedly less
  bitter and astringent.
- **Caffeine and chlorophyll rise**, which is why shaded teas are a vivid jade
  green and still carry a solid caffeine punch despite tasting so soft.

So gyokuro and good matcha taste sweet, marine, and savoury instead of vegetal:
same *Camellia sinensis*, grown in the dark for three weeks to trade astringency
for umami. Matcha then goes one step further — you whisk and drink the *whole*
ground leaf, so all of that theanine, caffeine, and catechin ends up in the bowl
instead of being left behind in a spent leaf.

## Brewing, by class

Water temperature tracks oxidation: the less oxidised and more delicate the leaf,
the cooler the water, or you scorch it into bitterness.

| Class | Rough water temp | Notes |
| ----- | ---------------- | ----- |
| Green | 70-80 °C (steamed Japanese greens cooler; gyokuro to ~50-60 °C) | delicate leaf scorches; keep steeps short |
| Yellow | 70-80 °C | like green, a shade more forgiving |
| White | 75-85 °C | forgiving; longer steeps pull the sweetness |
| Oolong | 85-95 °C (roasted and rock oolongs near boiling) | rewards many short infusions |
| Black | 95-100 °C | a near-full boil opens the oxidised leaf |
| Dark / pu-erh | 95-100 °C, after a quick rinse | the rinse wakes the compressed cake; steep it many times |

Two habits carry across all of them. **Gongfu brewing** — a high leaf-to-water
ratio in a small vessel, steeped many times for a few seconds each — reads a tea
more completely than one long Western mug, because you taste it change from
infusion to infusion. And **cooler is safer**: an under-hot cup of green is merely
mild, while an over-hot one is ruined — exactly the rule that governs a whisked
bowl of matcha.
