One plant, four drinks
Why Is Tea Different Colours?
Green tea, black tea, white tea and oolong all come from the same bush. The difference is how long the leaf was left to brown.
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Step 1 of 5
A torn leaf browns in air.
Break the leaf and an enzyme inside meets oxygen, and the leaf starts to brown. It is the same reaction that browns a cut apple, and it changes the taste as it goes.
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Step 2 of 5
Green tea stops it immediately.
Heating the fresh leaf destroys that enzyme within minutes. Nothing browns, and the drink stays close to what the leaf tasted like on the bush.
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Step 3 of 5
Black tea lets it run to the end.
The leaves are rolled to break them thoroughly and left for hours. The browning goes to completion, which is where the dark colour and the strong malty taste come from.
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Step 4 of 5
Oolong is stopped halfway.
The leaf is bruised at the edges only and watched until it has browned as far as the maker wants. It is the most hands-on of the four and covers an enormous range.
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Step 5 of 5
Brewing pulls out different things at different speeds.
The bitter compounds come out slower than the flavour ones, so time and temperature decide the result. Cool water and a short brew give a sweeter cup than boiling water and five minutes.
Herbal teas are not tea at all. Mint, camomile and rooibos come from completely different plants and share only the method.
The short version
One bush and one browning reaction, the same one that darkens a cut apple. Green tea stops it in minutes, black runs it to the end, oolong is caught halfway — and in the cup bitterness comes out slower than flavour.
Try it yourself
Brew the same teabag in cool water and in boiling water. The bitterness arrives with the heat.