Oolong Tea: Origins, Benefits and Complete Guide
By Trevor Ashworth, Certified Tea Sommelier, UK Tea Academy — Teatower
Oolong tea, often called "blue tea" or "blue-green tea", is arguably the most overlooked tea family in Europe — and yet one of the richest in complexity and character. This guide answers the questions we hear most often: what sets oolong apart from green tea and black tea, how much caffeine it contains, and how to brew it properly to unlock its full aromatic range.
What is oolong tea?
Oolong tea (also known as blue tea or blue-green tea) is a semi-oxidised tea, made like all true teas from the Camellia sinensis plant. What makes it special is its oxidation level, which ranges from 10% to 80% depending on the variety — making oolong the broadest and most diverse tea family in terms of flavour, sitting somewhere between the freshness of green tea and the depth of black tea.
Originally from China and Taiwan (where it is historically known as "Formosa tea"), oolong encompasses a remarkable range of styles: from light, floral oolongs such as Tie Guan Yin, to the roasted, woody Wuyi oolongs, and the Taiwanese ball-rolled oolongs that can be steeped multiple times.
Oolong, green tea, black tea: it's all about oxidation
- Green tea: unoxidised, heated shortly after picking. Fresh, vegetal flavour.
- Oolong tea: partially oxidised (10–80%). A very wide flavour spectrum — floral, fruity, woody or toasty depending on the level of oxidation.
- Black tea: fully oxidised. Bold, often malty or woody in character.
At Teatower, our closest offering to the traditional style is the Organic Milky Oolong, a silky, lightly creamy oolong tea — find it in our Oolong collection.
What does oolong tea contain?
Oolong contains caffeine, in varying amounts depending on its level of oxidation — generally falling between the caffeine content of a lightly oxidised green tea and that of a black tea for the most heavily oxidised oolongs. It is also rich in polyphenols and antioxidants, as is the case with all teas derived from Camellia sinensis.
This information is provided for general guidance only and does not constitute health claims within the meaning of European regulations.
How to brew oolong tea properly
Oolong lends itself beautifully to the gongfu method (short, repeated infusions), but a classic single infusion works wonderfully too:
- Water temperature: 85–95°C depending on the level of oxidation (lighter oolongs prefer a lower temperature)
- Quantity: one heaped teaspoon (2–3g) per 200–250ml of water
- Steeping time: 3 to 5 minutes for the first infusion
- Trevor's tip: ball-rolled oolongs can be re-steeped 3 to 5 times — simply increase the steeping time with each infusion and enjoy how the aromas evolve
Our oolongs to discover
Beyond the traditional style, Teatower offers a curated selection of flavoured oolongs that make the most of its characteristic silky texture:
- Organic Milky Oolong — vanilla and milk oolong, silky and creamy
- Un Noël Vanillé — vanilla-scented oolong, indulgent and warming
- Ange Gardien — goji and strawberry oolong, fruity and gentle
- Noisette Gourmande — hazelnut and almond oolong, comforting and rich
- Framboise Rose — raspberry and rose oolong, floral and fruity
Browse the full range in our Oolong collection.
Frequently asked questions about oolong tea
Does oolong tea contain caffeine?
Yes. The caffeine content of oolong varies according to its level of oxidation: a lightly oxidised oolong (closer to green tea) generally contains less caffeine than a heavily oxidised oolong (closer to black tea).
What is the difference between oolong, green tea and black tea?
All three come from the same Camellia sinensis plant. Green tea is unoxidised, black tea is fully oxidised, and oolong sits in between: its oxidation level ranges from 10% to 80% depending on the variety, which is why it is often called 'blue tea' or 'blue-green tea'.
Why do some oolongs taste so different from one another?
Because the term 'oolong' covers an exceptionally wide oxidation range. A lightly oxidised oolong (such as certain Taiwanese oolongs) retains much of the freshness of green tea, while a heavily oxidised oolong (such as certain Wuyi oolongs from China) can taste closer to a bold, woody black tea.
How do I brew oolong tea properly?
Use a higher water temperature than you would for green tea — 85–95°C depending on the level of oxidation — and steep for 3 to 5 minutes. Quality oolongs, often ball-rolled, are well suited to multiple successive infusions (gongfu method), with each steeping revealing new aromatic layers.
Can oolong tea be re-steeped?
Absolutely — in fact, this is one of its finest qualities. A good ball-rolled oolong can be re-steeped 3 to 5 times, simply by increasing the steeping time slightly with each infusion, allowing the aromas to evolve beautifully from cup to cup.
Have a question about our oolongs, or would you like a personalised recommendation? Come and see us in one of our shops in Waterloo, Namur, Liège or Rocourt — our team will be delighted to help.