What Is Oolong Tea? Taiwan's Half-Way Tea, and Why Bubble Tea Shops Use It

Oolong is a partly oxidised tea, half-way between green tea, which is not oxidised at all, and black tea, which is fully oxidised. The UK Tea & Infusions Association (UKTIA) puts oolongs anywhere from 10% to almost 80% oxidised. They come traditionally from China's Fujian province and Taiwan, in two broad styles: greenish rolled oolongs with a light, floral liquor, and dark oolongs with deeper, earthier flavours.

Oolong fits neither box, green or black. Here is what it is, where the name comes from, its two styles, its place in Taiwan, how it tastes, and where it goes in a bubble tea.

What is oolong tea?

Every true tea comes from the same plant, Camellia sinensis. What makes a tea green, black or oolong is oxidation: in the UKTIA's words, "the length of, or absence of, the oxidation step" during processing "is responsible for the distinctive flavours of black, green oolong and white tea".

Green teas are "totally unoxidised", black teas are fully oxidised, and oolongs sit between them: "partially oxidated (ranging from 10% to almost 80%)". The UKTIA names three styles:

• Traditional dark oolongs: 40 to 60% oxidised.
• Bao Zhong (Pouchong): lightly oxidised, 10 to 18%.
• Jade, or balled, oolongs: 20 to 30% oxidised, with the leaves rolled into tight balls.

That spread is why two oolongs can taste very different from each other.

Why is it called oolong?

For the look of the leaf. Quoting Jane Pettigrew's World of Tea, the UKTIA says "Oolong means 'black dragon,' and these teas are named for the brown-black, twisted leaves of dark oolongs that often have the appearance of snarling dragons or writhing serpents."

The light and the dark: oolong's two styles

The UKTIA describes oolongs as running "from greenish rolled oolongs (that give a light, floral liquor reminiscent of lily of the valley, narcissus, orchid or hyacinth) to dark brown leafed oolongs (that yield liquors with deeper, earthier flavours and lingering hints of peach and apricot)". The two are made in very different ways.

Dark oolongs. The freshly picked leaf is withered, then shaken or "rattled" in bamboo baskets or a bamboo tumbling machine to bruise parts of the leaf lightly. It is oxidised for a short time, then dried. Da Hong Pao, Great Red Robe, is among the China oolongs the UKTIA recommends.

Green oolongs. The withered leaf is wrapped in a large cloth and rolled in a special machine, then spread out briefly to oxidise lightly. The wrapping, rolling and oxidising are repeated until the leaf reaches about 30%, then it is dried. The most famous of these light, fragrant oolongs, says the UKTIA, is Tie Kuan Yin, with "a hyacinth or narcissus character".

Oolong and Taiwan

Taiwan is one of oolong's two homes. The UKTIA's definition opens "Traditionally from China's Fujian province and Taiwan", and it names Tie Kuan Yin as made in Fujian and in Taiwan. Pouchong, a lighter style still, is also produced in both, and the UKTIA describes its long, stylish black leaves brewing "a very mild cup with an amber infusion and a very smooth, sweet taste".

Taiwan is also where bubble tea began: our what is bubble tea page dates it to the 1980s, and lists oolong among the tea bases a bubble tea can be built on.

What does oolong taste like?

It depends on the style, and the UKTIA's two descriptions mark the ends of the range. A green, rolled oolong gives "a light, floral liquor reminiscent of lily of the valley, narcissus, orchid or hyacinth". A dark oolong gives "deeper, earthier flavours and lingering hints of peach and apricot". Most oolongs sit somewhere between the two.

Where does oolong go in a bubble tea?

As a base for both fruit teas and milk teas. In a fruit tea, US bubble tea suppliers' recipe titles pair it with peach, white peach and passionfruit, which fits the UKTIA's note of peach and apricot in the darker oolongs. In a milk tea, UK bubble tea menus list oolong milk tea and roasted oolong milk tea, and US recipe titles include a peach oolong milk tea and a passionfruit oolong with oat milk.

The tea trade itself would leave the milk out: the UKTIA's advice is that "All oolongs are better drunk without milk." An oolong milk tea is a bubble tea shop's way with the leaf, not the traditional one.

Is there oolong in TeaJoy?

No. None of our drinks is made with oolong: our packs print black tea, green tea extract, jasmine green tea flavour and matcha. What bubble tea and oolong share with us is a home. Our tea comes from the Taichung region of western Taiwan, and does bubble tea contain tea sets out the form the tea takes in each of our drinks. For the other teas behind bubble tea, see what is Assam tea and what is jasmine tea.

Questions people ask

Is oolong a green tea or a black tea?

Neither. Oolong is partly oxidised, so it sits between green tea, which is totally unoxidised, and black tea, which is fully oxidised. The UKTIA puts oolongs anywhere from 10% to almost 80% oxidised, depending on the style.

What does oolong mean?

"Black dragon". The UKTIA says the name comes from the brown-black, twisted leaves of dark oolongs, which can look like snarling dragons or writhing serpents.

Can you put milk in oolong?

Bubble tea shops do: UK menus list oolong milk tea and roasted oolong milk tea. The UKTIA's own advice is that all oolongs are better drunk without milk, so the plain cup is the traditional way.

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