Black tea is different from green tea and white tea or oolong in the way that it’s crafted. All tea is made from the same leaves of Camellia sinensis, much as all wine is made from grapes. In black tea, the key difference is oxidisation.
Black tea is intentionally oxidised to enhance specific flavour profiles.
· The catechins found in green and white tea are converted through oxidisation into theaflavins and thearubigins, which create a richer, more robust flavour.
· In some black teas, oxidisation creates a strength and astringency that balances beautifully with milk or sugar.
· In others black teas, the oxidisation is much more subtle to produce more elegant and subtle flavours that are best enjoyed with nothing added.
“Fully oxidised” is a phrase you will hear often about black tea. However, it is a perplexing mistake because 100% chemical oxidisation would reduce the leaf to ash.
· Black tea is oxidised to around 80–90%, at which point heat is applied (during the firing process) to stop the enzymatic reaction and dry the tea.
· Oolong is oxidised using more controlled techniques, at a range between 20–80%.
Green tea works in the opposite direction: oxidisation is intentionally prevented.
· Heat is applied shortly after harvesting, before oxidation can begin.
· This keeps the tea green, with fresh and bright flavours, and retains a high concentration of catechins and L-theanine.
White tea is the least processed of all:
· The leaf is withered and dried, with almost no intervention
· White tea has the most delicate flavours.
One small note on naming: what English speakers call black tea is not what the Chinese call it. In China it is hong cha (red tea) named for the amber colour of the brewed cup. The English name refers to the colour of the dry leaf. Dark tea in China is something else again: pu’er, a fermented tea and an entirely separate category.
