Flavour perception is a deceptively complex thing. Human taste buds are capable of sensing salty, sweet, sour and bitter (the four classical elements of human taste) plus umami (the savoury taste of glutamates such as MSG, found in things like mushrooms, soy sauce and meat) and probably fat (the jury is still out on this one, but the evidence is strong). However, none of those play a central role in tasting something like most good tea or wine!
Most of the flavour of the most interesting drinks comes from their aromas. Our sense of smell is easily the most elaborate of all our senses – unlike the five or so basic tastes detected by our tongues, or the three basic colours detected by our eyes, our noses are capable of distinguishing thousands of different molecules.
Complicating matters further is the interaction between olfaction (the sense of smell) and gustation (the sense of taste provided by the taste buds); sometimes we won’t be aware of an aroma until we taste something with our tongues, and sometimes a particular taste becomes obvious only when we smell something associated with it. The two are bound up together so tightly that most of the time, people are not even aware that they are ‘tasting’ things with their noses, not just their tongues. For this reason it is always worthwhile to be conscious of the smell of fine teas, wines, whiskies and so on before tasting them, but also aware that the depths of their flavour cannot be judged until they reach the tongue and the palate.
There’s more: Add to the gustation and olfactory components the trigeminal sensations of pain and heat triggered by both physically hot and spicy hot food; the effects of texture, known in the business as ‘mouthfeel’; and astringency – the quality of tea, red wine and some fruits which makes us pucker our mouths, regardless of how they actually taste.
So, to tea: What can we say about how tea tastes, and why? For a start, the overwhelming majority of true teas are at least a little bitter, and all are astringent to a greater or lesser extent. The tiny fragments of blended black tea used to make your basic tea bag for English tea are extremely bitter, and so astringent that the infusion is almost impossible to drink straight. Thankfully though, the molecules that give it these properties bind to the proteins in milk just as readily as they will to our tongues. They can also be more fully dissolved into the tea by adding lemon or some other mild acid – one of the few times when adding lemon makes something much less bitter. You will also notice that strong black tea clears and brightens almost immediately when lemon is stirred in, for exactly the same reason.
Lighter black teas like Darjeelings and Chinese black teas (Keemun, Yunnan and so on) tend to be much lesser bitter than their cousins, but this is largely because they are standardly brewed weaker. These teas have a depth of flavour coming from their subtle aromas, and many people feel that this goes to waste when they are made with milk, which has its own not-so-subtle smell. It might be argued, though, that a little milk is not offensive in a cup of the more robust light black teas, allowing for a stronger brew without totally overpowering the flavour.
Good green tea is usually not more than slightly bitter, as long as it is drunk while hot, and not brewed too strong. However, green tea bags are usually made with far too much tea, low-grade and broken up, and in my experience almost always make a bitter brew. Brewing temperature is absolutely crucial with green tea, which should never be made with boiling water; scalding the leaves that way not only removes much of their pleasant flavour, but gives them a new acrid flavour, which puts many people off the tea entirely. Many green teas have a flavour dominated by vegetative tones. This might be accompanied by a gentle smokiness, as in gunpowder tea and chun mee; rich, slightly flowery depths, as in pi lo chun (bi luo chun); or a sort of sea-sidey almost-fishiness in the case of most Japanese green teas, which sounds like it would be horrible but is actually oddly pleasant.
Oolong tea is tea which has been partially oxidised, placing it between green tea (which is plucked and dried quickly before the leaves can blacken) and black tea (in which the leaves are rolled or cut, and carefully oxidised over the course of several hours before drying). In general, it tends to have richer aromas than any other unflavoured tea, and most varieties are notably much less bitter than any black tea. There is enormous variety in the range of oolong flavours, and also extraordinary depth to them. Some are sweet, some flowery, some toasty, some autumnal, some have flavours which the English language is quite at a loss to describe. Good Chinese tea sets designed for oolong sometimes include separate ‘scent cups’, into which the tea is poured before it gets to the tiny drinking cup, just to give the tea drinker an opportunity to savour the aroma more deeply.
Like green teas, oolongs can generally be brewed several times, and each brew will often bring out different flavours from the last. Temperature is again important; though oolongs are not so thoroughly ruined by too-hot water, much of their taste will go to waste.
White tea is the lightest of all the true teas, made from young leaves plucked while they still have the baby-hairs on them and dried at once to preserve them in almost the same state they came off the bush. They have gentle flavours, never more than a tiny bit bitter when brewed correctly, often with a sweet aroma somewhat reminiscent of honey. Despite the softness of their flavours, there is a depth to them which should be lingered on. White teas must be brewed with water well below boiling point, and can be steeped repeatedly.
Pu-erhs, sometimes described as ‘post-fermented’, are a whole world of tea to themselves, despite being a relatively tiny niche market. Their musty aroma often borders on mouldy, which puts many people off, but they do have a pleasant, earthy richness to their taste which belies their smell. Pu-erh fans tend to be extremely enthusiastic about it, often to the puzzlement of the rest of the world. Pu-erh tastes like it must be good for you, and according to Chinese tradition and some scientific studies, it really is.
Some of the best-known of Chinese teas are flavoured, and derive most of their character not from the tea itself but from things added to it. Proper jasmine tea is flavoured by being left with drying jasmine flowers to absorb their flavour; lapsang souchong is smoked, traditionally over pine wood, to obtain its intense, tarry aroma; Earl Grey is scented with oil of bergamot, obtained from a particular kind of orange. Genmaicha, popular in Japan and Korea (where it is called hyun mi nok cha), is made of green tea with roasted rice, and it is the toasty flavour of the rice that dominates its taste.
Another toasty tea is hojicha, a rich brown tea made by roasting green tea. It has an unusually savoury taste, with a slightly nutty aroma; although it is not yet well-known in the West, it is generally extremely popular with those who have tried it. It is low in caffeine, and can be drunk hot or cold – for my money, it makes the most refreshing iced tea there is.