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Post-Manufacture Processing of Oolongs

by Lydia Kung

Another sub-category of Oolongs includes Aged and Baked teas. Here, there is a post-production step of heavy baking. Leaf and brew become darker, but should not have a burnt or over-fired taste. Flavor tends to be deeper, more concentrated, and definite notes of roasting but not smoke.

At the high end, the baking is known as “tan pei,” or charcoal roasting. Because of the labor intensive cost, only high quality teas get this treatment. For a spring tea, when the pluckings are plump and tender, a high temperature (140°C) is applied. The leaves are cooled, and then a lower temperature (120°C) is set. For an autumn tea with thinner leaves, lower temperatures are used so as not to scorch the leaves.

Note how prominently the two words for charcoal roasting appear on the label shown above. This step is a selling point. The little foil pouch here holds a few grams, just enough for one pot. This particular tea is nong-xiang, or “strongly aromatic.”

The finished cup retains the tea’s inherent vitality, but is smooth and satisfying, with a very high aroma. Each sip carries a concentration of the tea’s essence, but conveyed in a harmonious way.


Powerful Aged Oolongs largely come from Taiwan, and it’s easy to see why they are costly. Finished Oolong is placed in pottery jars where they will age for 8 to 10 years. Each year the tea is taken out and re-roasted, by charcoal at low temperatures, all performed under the supervision of experienced craftsmen, quite senior, obviously, given the years involved. We see here an example of hand-work that along with time have very definite consequences.

These Aged Oolongs are velvety smooth, deep amber in the cup, and robust on the palate. My personal take is that it’s somewhat of an acquired taste, and given the price, an understanding of the aging process goes a long way in appreciating such a tea.

We seem to have come full circle: we see work done by hand at the start of the entire process, followed by mechanical manipulation, and see in some high end teas where value-enhancing steps at the very end are also done by hand.

I return once again to the notion of a continuum for conceptualizing all teas: on one end are non-oxidized, very high quality Green teas that are entirely handcrafted, and at the opposite end we see fully oxidized, even industrial, mass manufactured Black teas, and in between we see Oolongs in all their delicious complexity stretching in both directions.