Blue tea is between green tea and black tea. Depending on its origin, it will be closer to one or the other and will have the same characteristics. Semi-fermented oolong tea can therefore be low in theine like a green tea or full-bodied like a black tea depending on whether it has undergone more or less oxidation.
Tea fermentation: a process codified since 1880
Tea fermentation is a process that can take two different forms. Green and white teas are obtained by drying, that is to say that the leaf of Camelia Sinensis is simply dried. While the fermentation of black tea as well as fermented oolong tea is based on an oxidation phenomenon. The fermentation process of tea is composed of different phases that give the tea its characteristics since all teas are derived from the same plant: Camelia Sinensis. It is therefore according to the fermentation or oxidation of tea that it will be classified as green, black, white or oolong.
The fermentation process of tea
- The tea leaves are picked by hand
- They are then withered
- Then comes the desiccation or dehydration
- Then comes the oxidation for black, oolong and some yellow teas
- The rolling of the tea is also a manual action
- Then the tea is dried
- Finally it is sorted or sifted
- And black teas and some oolong teas are cooked or roasted
Fermented oolong tea: 4 levels of oxidation
In the case of fermented oolong tea, the degree of oxidation of the tea is very variable. Fermented oolong tea will undergo the fermentation of green tea and then an oxidation identical to black tea except that it is voluntarily interrupted several times during the process. It is this particularity that gives semi-fermented oolong tea its powerful aromas. While the fermentation of oolong tea is generally short, it can extend and the tea can reach 40 to 70% oxidation. The degree of oxidation of blue tea is classified into 4 levels:
- Low oxidation oolongs (10 to 30%), which are the closest to green tea and most often come from China.
- Strongly oxidized oolong teas (40 to 70%), closer to black tea, these are generally Taiwanese teas.
- Older oolong teas, which have been roasted several times, are aged teas that can be 20 or even 25 years old. These teas from Taiwan are rarities.
- Multi-roasted young oolong teas are exclusive teas, made to look like old teas.
Oolong tea is the only tea that can be brewed several times.
The fermentation or oxidation of oolong tea gives it different properties from other teas. Considered as a tea for aging, oolong tea is also the only tea that can be brewed several times.