爲什麼英國人如此鍾愛茶的味道(1)

Tea has become entrenched in the British way of life, from the humble tea break to the afternoon tea to be enjoyed – in a jacket and tie, of course, gentlemen – at the very swankiest of London hotels.

從簡易的普通茶歇，到倫敦頂級奢華酒店供應的下午茶，飲茶儼然已成爲英倫生活方式中不可或缺的一部分。而爲了享用茶餐，紳士們甚至還要穿着西裝、打上領帶。

But what are the molecules behind the taste of this beloved beverage? And does how you take your tea say something about who you are?

而身爲飲品界的英倫寵兒，茶香的根源到底是什麼呢？我們又能否從一個人喝茶的方式中，多少窺探出些許關於其真實境況的信息呢？

To answer that, it’s worth first trying to work out what it is exactly that makes tea taste the way it does. Tea’s flavour is intimately affected by how it is grown, processed, and brewed – beginning with the light. Tea bushes – Latin name camellia sinesis – are grown in terraces all over the tropics and subtropics. But if the intent is to make certain kinds of green tea from them, like matcha, growers will make sure they are carefully shaded with nets or mats. Less sun causes them to produce more chlorophyll as well as fewer polyphenols, a class of molecules that imparts tea’s singular astringency.

想要解答這些問題，首先，我們有必要設法搞清楚：究竟是什麼賦予了茶以獨特的味道。茶葉的味道深受其栽培方式、加工方式以及沖泡方式的影響。而所有這些都得從陽光說起。在全球熱帶和亞熱帶的梯田中，人工種植的茶樹（拉丁名爲“camellia sinesis”）隨處可見。然而，倘若種植者意在將它們製作成某種特定類型的綠茶（比如抹茶），他們便會小心翼翼地用網眼織物或者席子遮住茶樹，確保它們不會過度曝光。這是因爲太陽光照越少，茶葉生成的葉綠素就會越多，同時多酚類物質就會越少，而茶本身那種奇異的澀味便是源自於後面一類分子。

Of course, some of us may like that taste, and tea processing can amp it up. After the new leaves and buds have been plucked from a bush, they are laid out to dry. How long they lie again depends on the kind of tea intended. For green teas, the leaves are almost immediately tossed in a hot pan or steamed (tea might look like the rawest of edibles, but it is actually cooked, or at least heat-treated). An oolong results when the leaves are dried a little, bruised and only then cooked. And a black tea – the most popular variant, accounting for 78% of the tea drunk world-wide – results when the bruised leaves dry quite a long while before being finished in the pan.

當然，我們之中可能有些人會喜歡那種味道，而且製茶工藝還可以加重這種味道。茶農先將新葉和嫩芽從一株株茶樹上採摘下來，然後把它們攤開來放置，以便晾乾，而攤放時間的長短則取決於要製作的茶的類型。如要製成綠茶，茶農幾乎需在第一時間就把鮮葉扔進熱鍋里加熱殺青，也有的綠茶是蒸氣殺青（儘管乍一看上去，茶可能像最原始而未經加工的食品，但實際上，茶是烹熟的，或者起碼也經過了熱處理）。如要製成烏龍茶，茶農需要在葉子稍幹一些後，將其搗碎、揉捻，在這之後再烘焙烹熟便可大功告成。而如果要製成紅茶，茶農需先把葉子搗碎、揉捻，再將它晾相當長的一段時間，然後在鍋中完成最後的烘炒。紅茶是最爲流行的茶品種，佔到全世界茶飲消費總量的78%。

What’s behind all this is that as the tea leaves are drying, enzymes native to the tea plant are busily transforming simple molecules into more complex ones. The longer the tea spends drying, the longer those enzymes have to work – and the more these molecules build up in the tea leaves. The most famous in tea-chemistry circles is probably theaflavin, a tangle of carbon rings responsible for some of the ruddy colour of black teas as well as some of the astringency.

蘊藏在這一切背後的化學原理，就是茶樹原生的各種酶素在茶葉逐漸晾乾的過程中，馬不停蹄地將結構簡單的分子轉化成結構複雜的分子。茶葉晾乾的時間越長，這些酶素髮揮效用的時間就越長，進而這些在茶葉中組合聚集起來的分子也就越多。在茶葉化學界最負盛名的恐怕要數茶黃素了，這是一團糾結在一起的碳環，因了它的存在，紅茶多了幾分紅潤的色澤，還多了些許澀味。

Firing the tea leaves calls the process to a halt by destroying the enzymes. As a result, there’s very little theaflavin and related molecules in, say, green teas. But aside from polyphenols, hundreds of other compounds build up in the tea over time; their roles in crafting tea’s bouquet and taste are not yet clear. Regardless, the end result is a different chemical profile for each kind of tea.

茶葉的烘烤焙制工藝開始後，這一反應過程因酶素被摧毀而被迫終止。因此，在諸如綠茶等一些茶製成品中，茶黃素及其相關分子的含量微乎其微。不過，隨着時間的推移，除了多酚類物質，茶葉中還組合聚集了數百種其它種類的化合物；而在茶的香味和口感的締造過程中，它們發揮了怎樣的作用，如今尚無定論。無論如何，最終的結果便是，每種茶都有了不同的化學剖面。

Given how much tea people drink, there's growing interest in understanding whether this habit has any medical benefits. It appears that molecules found in tea can protect cells in a dish from some kinds of damage, but despite copious research,there is conflicting evidence on whether tea-drinking provides benefits beyond warm hands and an alert mind.

鑑於人們的飲茶量如此之大，學界對於飲茶習慣是否具有醫學效用這一問題的研究興趣日益高漲。儘管有大量研究表明，在茶葉中發現的分子似乎可以在培養皿中保護細胞，使其免受某些類型的損傷，但在飲茶是否能爲人們帶來暖手和提神之外的其它益處的這個問題上，各種證據之間又充滿了矛盾。

Because, of course, there are the stimulants. Brewed tea has roughly half the caffeine of an equivalent volume of coffee, but it is still plenty for a mid-afternoon pick-me-up. You might have heard that caffeine in tea gives a different high from the caffeine in coffee. Many studies have found that if this is the case, it’s because of an amino acid called theanine, which occurs in tea. When volunteers consume both caffeine and theanine – versus caffeine and other tea molecules – they show moderately more alertness and better ability to switch between tasks than with caffeine alone. The amount in a given cuppa may not be the same as the doses given during a study, however, and the effect of theanine is not enormous. But all on its own, the caffeine will give you a nice lift.

這是因爲茶的確對大腦神經有刺激性。雖然與同等劑量的咖啡相比，煮好的茶所含的咖啡因大約只有前者的一半，但依然足夠起到午後提神的作用。你或許已有耳聞，茶中的咖啡因所帶給人的興奮感與咖啡所含的咖啡因有所不同。許多研究已經表明，如果事實的確如此，那麼差異的出現源自於茶葉中存在的一種氨基酸，它名爲“茶氨酸”。當志願者同時攝入咖啡因與茶氨酸時，相較於同時攝入咖啡因與其它的茶分子（單靠咖啡因醒神），他們表現出略微強一些的敏捷性和更好的多任務切換能力。不過，一杯茶水中所含的茶氨酸和研究中所用的劑量可能會有差異，而且茶氨酸的效用也並不是很大。但是，就咖啡因自身而言，茶的提神效果還是挺不錯的。