Blue tea sits between green tea and black tea. Depending on its origin, it leans closer to one or the other, sharing the characteristics of each. Oolong tea, with its variable oxidation, can be low in caffeine like a green tea or full-bodied like a black tea, depending on how far the oxidation process has been taken.
Tea oxidation: a codified process since 1880
Tea oxidation can take two distinct forms. Green and white teas are produced through desiccation: the Camellia sinensis leaf is simply dried. Black tea and oolong tea, on the other hand, rely on an oxidation process. This oxidation process unfolds through several stages, each shaping the tea's final character. Worth remembering: all teas come from the same plant, the Camellia sinensis. It is the degree of oxidation that determines whether a tea is classified as green, black, white, or oolong.
The tea oxidation process
- Tea leaves are hand-picked
- They are then withered
- Desiccation or dehydration follows
- Oxidation then takes place for black teas, oolongs, and certain yellow teas
- Rolling is also carried out by hand
- The leaves are then dried
- Finally, they are sorted or sifted
- Black teas and certain oolongs are fired or roasted
Oolong tea: 4 levels of oxidation
When it comes to oolong, the degree of oxidation is highly variable. Oolong tea undergoes the same initial process as green tea, followed by an oxidation similar to black tea, with one key difference: it is deliberately interrupted several times throughout the process. This is what gives semi-oxidized oolong its complex, powerful aromas. While oolong oxidation is generally brief, it can be extended until the tea reaches 40 to 70% oxidation. The oxidation level of blue tea is classified into 4 grades:
- Lightly oxidized oolongs (10 to 30%): closest to green tea, these are most often produced in China.
- Heavily oxidized oolongs (40 to 70%): closer to black tea in character, these are typically Taiwanese teas.
- Aged oolongs, the result of multiple roasting sessions, are aged teas that can be 20 to 25 years old. These Taiwanese teas are true rarities.
- Young multi-roasted oolongs are exclusive teas, crafted to mirror the profile of aged oolongs.
Oolong: the only tea that can be steeped multiple times.
The oxidation process gives oolong tea a character all its own. Considered a tea that improves with time, oolong is also the only variety that can be steeped again and again, each infusion revealing new nuances.