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🍵 Tea: oxidation, terroir and six categories

Six packets, one evergreen. The colours in your cupboard are what a copper enzyme, a hill and sometimes a fungus did to Camellia sinensis.

6
lessons
~30 min
to learn
🔬 Science
subject
Adults
level
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What you’ll learn

  1. Six packets, one evergreenName Camellia sinensis as the single species behind true tea, split China type from Assam type, and keep herbal infusions off the list.Two leaves and a bud. Two varieties. Six later decisions. Chamomile is not invited.
  2. The enzyme that paints the leafTreat PPO as a copper enzyme that turns catechins into theaflavins and thearubigins, and stop calling that browning a fermentation.Wake it in the wither, hire it in the roll, or kill it with heat. Oxygen sets the pace.
  3. Heat that stops the clockContrast kill-green, a live-enzyme wither, and yellowing, and read Zhao's phenolic table as a map of those choices.Steam or pan for green. Weather for white. A sealed rest for yellow. Catechins stay or slowly leave.
  4. Bruising on purposeFollow semi-oxidation versus full oxidation through bruising, orthodox rolling and CTC, and keep Tanaka's 70–80 percent black-tea share in view.Same PPO. Different distance. A granule and a whole leaf are two surface areas, not two species.
  5. The pile that is actually fermentedSeparate dark tea's microbial pile and theabrownins from black tea's leaf PPO, using Fuzhuan, pu-erh and the brick as cargo.Kill the leaf enzyme. Hire a fungus. Compress what has to travel.
  6. The hill writes the cupUse Zhang's place-and-elevation point, FAO's 6.7 million tonnes, and Zhao's caffeine table to keep terroir and processing from stealing each other's jobs.Hill first, bruise second. Caffeine ignores the colour code. Brew two packets tonight.

Questions this course answers

Where do the six true-tea categories actually come from?

UF/IFAS and Zou: all true tea is Camellia sinensis. The six categories are processing decisions about oxidation and, for dark tea, microbes.

Match each name to what Zou's review actually gives it

Zou 2024: PPO paints black tea; theabrownins belong to dark tea after the leaf enzyme is killed; sha qing is how green tea refuses the meeting.

Put orthodox black-tea steps in the order that actually hires PPO

Zou: activity rises in the wither, peaks in the roll, falls during oxidation, and dies in the dryer. UF/IFAS's home sequence is the same story.

In dark tea, whose PPO is doing the late work in the pile?

Zou: dark-tea PPO is microbial. Fuzhuan's activity tracks Eurotium cristatum. Black tea uses the leaf's own enzyme instead.

About how many million tonnes of tea did FAO's Intergovernmental Group report for 2022?

FAO IGG: world tea (black, green, instant and other) reached 6.7 million tonnes in 2022, after about 3.2 percent annual growth over the decade.

Why did Zhao's white teas land near the fermented teas for total phenolics, instead of between yellow and oolong?

Zhao: no steaming, oxidases remain active, polyphenols are lost in the wither. A pale cup is not a proof of a virgin leaf.

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