Oolong Tea Oxidation

Oolong tea is a semi-oxidized tea. Tea oxidation is commonly referred to as tea fermentation but this term is misleading. Strictly speaking, fermentation is an anaerobic process, but tea oxidation involves exposing tea leaves to the air. Tea oxidation is one of many steps in the production of oolong tea.

Oolong tea from Taiwan is grown from the Camellia Sinensis plant. All tea - black tea, green tea, and Oolong tea come from the same plant, and it is largely the degree of oxidation that differentiates them.

Green tea is un-oxidized, and black tea is fully oxidized. Oolong tea is in the middle of tea oxidation - usually between 20% and 60% oxidation.

Oxidation Levels

Oxidation levels can be precisely determined by measuring the levels of various compounds in the tea leaves, but this type of analysis is impractical for most tea producers due to the cost. Each batch of tea would have a slightly different reading due to differences in season, weather conditions, and processing times.

Therefore it is more suitable to express oxidation in general terms such as unoxidized (for green tea, but even this is not truly accurate since oxidation begins as soon as the leaves are plucked), lightly oxidized (for green oolongs) and medium for darker oolongs.

Most of the teas we carry are lightly oxidized, very similar to each other in terms of oxidation levels. The exceptions are our Tan Pei Oolong Tea and our Hong Pei Jin Xuan tea which are oxidized to the medium range. Both of these teas are also more heavily roasted than our other teas, which increases their robustness.

We also carry a fully oxidized black tea from Alishan.

We always suggest trying out our samples before buying larger batches so you know exactly what to expect.

Processing Oolong Tea - Oxidation

One of the first steps in processing Taiwan oolong tea is to toss the leaves in large bamboo baskets. This bruises the leaves so that they oxidize evenly. After this tossing, the fresh leaves are left exposed to the air. The leaves react with the oxygen and begin to turn brown, much as leaves from a tree turn brown after they fall from the tree.

The oolong tea oxidation process is stopped by pan roasting the leaves. Judging the correct time for pan roasting the oolong tea leaves requires extensive experience in oolong tea processing. Tea masters participate in oolong tea processing competitions to demonstrate their skill at this fine art.

The many steps involved in processing tea leaves into fine oolong tea from Taiwan is one of the reasons why Taiwan oolong tea is so valued by tea connoisseurs around the world. Buy oolong tea today and start enjoying this wonderful, healthful beverage.