Oolong tea

Oolong tea (wulong, semi-oxidised tea) is tea from Camellia sinensis leaf that is only partly oxidised: processing stops halfway between green and black. Under the classification of the UK Tea & Infusions Association (UKTIA), oolong oxidation ranges from about 10 % to nearly 80 %, so the type covers both light floral teas and dark, deep ones.

The plant is the same tea bush that gives green and black tea. What differs is the processing; the general scheme is on the Tea oxidation page.

Oolong takes a longer route than most teas. The leaf is plucked and withered, then shaken and tossed again and again: the edges bruise, and that is where oxidation starts. A 2024 study of Aijiao oolong names this repeated bruising as the main factor in quality. The leaf is then heated to stop the enzymes, rolled and dried, sometimes roasted as well. The degree of oxidation varies: Pouchong (Bao Zhong) 10–18 %, Jade 20–30 %, dark oolongs 40–60 %.

The home of the type is Fujian province in China. In the south, Anxi makes Tie Guan Yin; in the north, the Wuyi mountains give the rock teas Wuyi Yan Cha and Da Hong Pao. Mount Wuyi has been a UNESCO World Heritage site since 1999. Guangdong, near Chaozhou, makes Fenghuang Dan Cong, and Taiwan is a large oolong region of its own.

Green oolongs taste light and floral, dark ones earthier, with notes of peach and apricot. In USDA tables a 100 g portion of brewed oolong holds 16 mg of caffeine, so a 240 ml cup comes to roughly 38 mg (our estimate).

Green tea shows 12 mg and Black tea 20 mg on the same basis, so oolong sits midway on caffeine, just as it does on oxidation. What sets it apart from White tea is the shaking: white tea is only withered and dried. People sometimes confuse it with Darjeeling tea, but Darjeeling is a region in India, not a way of processing.

On the pack, look for a place name: Anxi Tie Guan Yin, Wuyi Yan Cha, Wuyishan Da Hong Pao, Fenghuang Dan Cong. The EU–China agreement on geographical indications took effect for these names on 1 March 2021, so a PGI symbol may appear on the label.

UKTIA's advice for oolong is 3–5 minutes in the pot or cup, no milk, and one teabag or a heaped spoonful of leaf for each serving. Its table gives no separate water temperature for oolong: about 80 °C for green tea, 90–98 °C for black. Brewing in small, repeated portions is covered on the Gongfu tea page.

Why this matters to you: once you know the oxidation level and the place name, you can guess the taste before the first cup.