If it walks like a duck
I love drinking oolong tea. I devote my business to the promotion of oolong tea. I search out oolong tea. I proselytize on behalf of oolong tea. I am fully vested in oolong tea.
But what on earth is an oolong tea? Formerly this question was easily answered. Recently, however, the definition has become cloudy and unnecessarily confused.
The classic answer has been that oolong tea is “between green tea and black tea;” that it is partially oxidized tea. True enough, an oolong is partially oxidized. Partial oxidation is a necessary condition of being classified an oolong tea. But is it a sufficient condition? Many new teas from countries like India and Nepal and Sri Lanka are made using black tea equipment and techniques but, because they are only partially oxidized, are marketed and sold as oolong tea. Are these authentic oolongs? Are they oolongs at all? I argue that they are not. And this is an emphatic NOT!
Mine is an uncomfortable position to hold for it implies that the classification system based upon the classic six tea types identified by the Chinese and subsequently adopted as a standard around the world is fundamentally inadequate. We cannot shoehorn all of the teas now being made into the current, widely accepted, taxonomy. This isn’t simply “uncomfortable”, for many, this is tea heresy. Am I to be cast out as apostate?
Actually a form of my particular brand of heresy has been around for a long time and is widely known, though rarely spoken of, in tea circles; you see, all tea is partially oxidized. Oxidation (or more correctly enzymatic browning) begins as soon as the leaf is plucked. Green tea is a little bit oxidized (trivial) and black tea is not fully oxidized (not trivial.) In fact the oxidation levels of black tea are often deliberately manipulated so as to emphasize different components of taste.
Sticking with the non-trivial fact that black tea is not fully oxidized leads to the conclusion that partial oxidation may be a necessary condition but it is not a sufficient condition for oolong tea. Perhaps then, we could say that black tea is highly oxidized and oolong is not. But what is “highly?” Some oolong tea is oxidized to 80 – 85% and more; some black tea is as low as 85-90% (and lower.) Oxidation level simply is not a good way to classify teas for it does not provide an unambiguous way of distinguishing among tea types.
If we cannot classify teas by oxidation level, what criterion do we use? We use production method. A green tea follows certain production steps, a black tea different ones and oolong teas still others. The key factor in each case is not the oxidation level but the way in which oxidation is retarded or encouraged. Oxidation is retarded and stopped by the application of heat or by the removal of moisture; it is encouraged by breaking down the cell structure of the tea leaf to allow oxidation to occur more rapidly. Oolong teas and black teas use very different methods to initiate oxidation and then to stop it.
Oolong tea is tumbled or shaken (yao qing) to bruise the outer edges of the leaves and allow for a slow and controlled oxidation. Black teas are rolled on a rolling machine designed to break down the cell structure of the entire leaf to encourage oxidation. Bruising vs. rolling. Any tea where the leaves are rolled before the tea is “fixed” (oxidation stopped) is not an oolong tea. Any tea not employing the tumble or shaken method of encouraging oxidation is not an oolong tea.
Yet sometimes, for tea made using the rolling technique, oxidation is stopped before it progresses to the end. This, generally, but not always,is accomplished during the drying process when moisture is removed from the tea leaves. Sometimes these teas are promoted as oolong teas because they are partially oxidized. But they are not oolong teas and they do not taste like oolong tea. They are partially oxidized black teas.
Oolongs (as opposed to those teas masquerading as such) are oxidized during and after the bruising process and the oxidation is stopped by pan firing. Only after this pan firing, are the tea leaves rolled and then dried.
Paving the road to hell
Some have suggested that the key to determining whether a tea is an oolong or not is to be found in the intention of the maker. If the tea maker intended to make an oolong we should judge the partially oxidized result as an oolong. This simply doesn’t hold water. If someone intends to build a jet plane but uses helicopter parts and a helicopter assembly line they usually end up making a helicopter (if not a mess.) The result is a helicopter regardless of the intent of the maker. The helicopter may fly beautifully, it may even fly better than any jet plane extant, but it is still a helicopter, not a jet plane. We need a category for helicopters; don’t call them jet planes.
There is no question that black tea can be superb.There is no doubt that some black teas sold as oolongs are excellent. But a partially oxidized black tea is still a black tea and not an oolong tea. No matter how fine it may be.
That’s my view. What do you think?
 The six types are: white tea, green tea, yellow tea, oolong tea, red/black tea, dark tea. Each of these types is associated with an oxidation level: green tea is not oxidized, black tea is fully oxidized, oolong tea is partially oxidized etc. In his superb book (every tea lover should own a copy) Tea: A user’s Guide Tony Gebely adds a seventh type he calls altered teas. We don’t need to be concerned with those here.
 See Eric R. Scott “The science and nomenclature of tea processing: Part 1: Enzymatic browning.” http://www.teageek.net/blog/2017/02/tea-terminology-part-1.
 See Will Battle’s excellent new book, The World Tea Encyclpaedia: The world of tea explained from bush to brew.
 Tony Gebely also claims to use production method but he then stretches the oolong category to include black tea methods. Tony’s system is really a classification by oxidation. See his Tea: A user’s guide p. 37-38 and especially his blog posting at https://www.worldoftea.org/nuances-of-tea-classification/.
 Some new area tea (Thailand, Viet Nam, New Zealand as well as India and Sri Lanka) is produced using oolong techniques. These are, I would argue, true oolongs.