Dong Ding Oolong Tea and Withering ─ Part 2 [Withering of Dong Ding Oolong Tea]

In our previous article, we discussed the relationship between withering and enzymes.

In this second half, we will look at how this influences regional characteristics and, in turn, impacts the flavor profile.

On the Flavor of Dong Ding Oolong Tea

In terms of aroma, it seems rich in geraniol, linalool, and nerol, leaving a strong impression of floral notes. In my own experience, I have often encountered teas with a touch of sweetness or a character reminiscent of ripe yellow peaches from other regions. It's like hops, isn't it?

It is also an interesting aspect of the aroma that common oolong teas are high in these same aromatic components. Even when the primary aroma is the same, if there is even the slightest difference in other aromatic components, the balance of the fragrance can shift.
It is not just because the aromatic components have changed; one must not overlook the fact that the "aroma threshold" also shifts when different aromatic components are mixed together.

For example, Dong Ding Oolong sometimes exhibits a sweet, lactic-fermentation-like scent, such as lactones. This can trigger a shift in the threshold of other fresh, green aromatic components, suddenly making them perceptible.

Production Process of Dong Ding Oolong Tea

The above is an example of the production method for Dong Ding Oolong. After withering, the technique of Yaoqing—where the leaves are agitated to level out moisture while slightly bruising them to trigger a small amount of enzymatic reaction—is quite interesting.

Characteristics of the Region where Dong Ding Oolong is Produced

It is mainly produced around "Dong Ding Mountain" in Lugu Township, Nantou County, central Taiwan. It seems to be blessed with an ideal natural environment for tea cultivation, including a mountainous area at an altitude of 600–1200m, complex topography, a warm and humid climate, abundant mist, and fertile soil.

The features of this region are the "large temperature difference between day and night" and "frequent occurrence of mist."

Aromatic components are generated due to stress from daytime light or insect damage, but these are often metabolized during the night. However, when the nighttime temperature drops significantly, these metabolic processes slow down, resulting in aromatic components being more likely to remain in the leaves. This is one of the reasons why it is a celebrated production area.

The amino acids (such as theanine) contained in tea are used to produce polyphenols as a defensive reaction against light, following a route that turns them into catechins. Therefore, the frequent occurrence of mist acts as a shield against light, making it easier for the leaves to develop a full-bodied flavor. This is the second reason.

There was also a theory that high humidity leads to the stabilization of chemical changes, but I was unable to grasp that point alone.

Withering in such a region

① Relatively long drying at low temperatures (10-20°C)

General withering is apparently done at 20-30°C, but in the Dong Ding Oolong region, temperatures can sometimes drop below 20°C. Since enzymatic reactions slow down at low temperatures, it is said that this allows for the generation of aromatic components to be expected more stably with less unevenness.

② Retention of aromatic components

Lower temperatures appear to reduce volatility and decrease metabolic risks.

③ Good ventilation

The region is situated in complex mountainous terrain, and natural winds blowing from various directions seem to allow for humidity control without unevenness.

④ Numerous slopes

Water runoff from the tea leaves is less likely to accumulate, preventing humidity from rising sharply. While it feels like a slight stretch, it seems plausible.

The ANTELOPE team would like to prepare ourselves to output this knowledge so that we can apply these techniques, which are intertwined with regional characteristics, to our mead in the future.