Classification of Cha
The leaves of Camellia sinensis, or "CHANOKI", contain an oxidative enzyme called polyphenol oxidase. When the picked leaves are crushed well, the tissue cells inside are broken, their contents are mixed, and the oxidative enzymes hasten fermentation. Based on the process to control the fermentation, we can classify tea into five types.
茶の分類
「チャノキ」の葉には酸化酵素（ポリフェノールオキシダーゼ）が含まれている。葉を摘んで揉むと、葉の組織が壊れて細胞の内容物が混ざり合い、酸化酵素による発酵が進んでいく。この発酵をどのようにコントロールするかにより、おおよそ以下の５種類に分けることができる。
１. GREEN TEA / Non-fermented tea
(processed without any oxidative fermentation; relative fermentation grade: 0%)
The tea leaves are put under heat treatment to deactivate the oxidative enzyme in them, immediately after they are picked (once picked, the leaves have already started slight fermentation.) The heating is done either with steam which is a method unique to Japan, or in an iron pot, as is practiced in a part of the Kyushu region or in China. With the enzymes deactivated, the ingredients of the produced tea can remain almost as they are in fresh leaves. In particular, the tea preserves the green of the leaves well, and thus is called green tea.
１. 緑茶 / 不発酵茶
(酸化発酵を行わないもの。発酵度 ０％)
茶葉を摘み取った後すぐに熱処理をして茶葉中の酸化酵素の活性を止めるのが特徴（摘み取った茶葉はすでに軽い発酵が始まっている）。加熱方法は、日本独特の蒸気で蒸す方法、九州地方の一部や中国で行われている鉄製釜で炒って仕上げる方法がある。酵素を失活させるため茶の成分がフレッシュな茶葉に近い状態で残り、茶葉の緑色がよく保たれ緑茶とよばれる。
２. WHITE TEA / Weakly fermented tea
(processed through very weak oxidative fermentation;
relative fermentation grade less than 10%)
The picked tea leaves first go through a withering process (leaves are left withering to lose contained water and to encourage fermentation. The withering takes place either outside under the sunlight, or indoors.)
Thereafter, the leaves go under a peculiarly simple process of slow drying over a low flame. Of the six kinds of tea, only this white tea avoids crumpling, namely the artificial enhancement of fermentation and adjustment of the leaf shape at the same time by strong crumpling. This causes the fermentation to progress gradually and helps the flowery sweet taste and fragrance to develop. At the same time, the oxidation of stimulant ingredients like polyphenol takes place, which makes the produced tea taste mild enough for even children.
２. 白茶 / 弱発酵茶
(ほんの少し酸化発酵させるもの。発酵度 １０％以下）
摘まれた茶葉を萎凋（放置して萎れさせ、発酵を進めるとともに水分を飛ばすこと。屋外での日光萎凋をする場合と室内萎凋をする場合がある）をした後、とろ火にてゆっくりと乾燥させるという中国茶の中では特に簡素な行程となっている。プーアル茶や緑茶よりも歴史が古く、六大茶類の中で唯一白茶だけが「揉捻（揉みこんで人為的な発酵を促進させ、同時に形を整える工程）」がない。そのため発酵はゆっくりと進み、これにより花のような甘い香りと味が生成される。同時にポリフェノールをはじめとする刺激性の成分が酸化されることで子供でも飲めるマイルドな口当たりのお茶に仕上がる。
What is Cha
Originally, tea is a drink that is made by processing the leaves and stems of the evergreen "CHANOKI（茶の木、茶樹）Scientific name: Camellia sinensis " belonging to the genus Theaceae Camellia."
Palatable beverages using leaves and fruits that do not use tea leaves are also generally referred to as "tea."
茶とは
本来、茶とはツバキ科ツバキ属に属する常緑樹「チャノキ（茶の木、茶樹）学名：Camellia sinensis」の葉や茎を加工して作られた飲み物。茶葉を使用しない植物の葉や果実などを用いた嗜好性飲料も総じて「茶」と称する。
３. BLUE TEA / Semi-fermented tea
(fermentation proceeded moderately; relative fermentation grade approximately from 15 through 70%)
The sort of tea that Oolong tea represents well. The picked tea leaves go through withering, while artificial encouragement of the oxidative fermentation by shaking or kneading (called YAO-QING, literally meaning "shaking blue") is applied in between. Later at a relevant stage of fermentation, the process called SHA-QING meaning "killing blue", or heating to stop the fermentation, follows to realizes the semi-fermentation. There are different brands showing different levels of fermentation : Wenshang Pouchong is at around 15%; Dong Ding Oolong and other high-mountain tea from 15 to 30%; Iron Goddess Guanyin 40 to 50%; Oriental Beauty at about 70 through 80%.
The tea is finished through roasting, after the leaves are crumpled into the shape of a ball, a stick, etc that maximises their taste and flavor when steeped.
３. 青茶
（半発酵茶：ある程度酸化発酵を行わせるもの。発酵度１５％から７０％ぐらい）
烏龍茶に代表されるお茶。摘まれた茶葉を萎凋させ、その途中に揺らしたりこねたりして人為的に酸化発酵を促進させる揺青（ようせい）という行程を加え、期をみて殺青（火入れをして発酵を止める）させた半発酵茶。
銘柄によって発酵の度合いが異なり、文山包種茶が１５％位、凍頂烏龍茶や高山茶が１５～３０％位、鉄観音などが４０～５０％位、東方美人が７０～８０％位。球状や棒状等、茶葉の味や香りを最大に引き出されるよう揉捻し、最後に焙じて仕上げる。
4. BLACK TEA / Completely fermented tea
(oxidative fermentation is done completely;
relative fermentation grade 100%)
After the leaves are picked, they are withered and next heavily rolled or kneaded to destroy tissue cells and thus to encourage oxidative fermentation. Thereafter, the "color development" takes place as a process peculiar to black tea production. This is actually sufficient oxidative fermentation done in a short period under controlled temperature, humidity and ventilation. When tea leaves turn to red-brown properly, the leaves are dried again to stop the fermentation. After this, the tea is finished by roasting.
Polyphenol Oxidase in the leaves causes oxidative polymerization of the catechins (safe to regard as tannin) inside into red pigments like theaflavin (red-orange) and thearubigin. At the same time, several aromatic components are generated to yield the flowery or fruity bouquet of the tea.
Black tea is produced in more than twenty countries in the world, amounting to over 80% of the world tea production.
４. 紅茶
（完全発酵茶：酸化発酵を完全に行わせるもの。発酵度 １００％ ）
茶摘後、萎凋して茶葉を萎れさせ、次に茶葉を揉んで細胞組織を壊すことで酸化発酵を促し（揉捻）、続いて紅茶独特の行程である「転色（温度や湿度、通気性を調整して短時間に十分発酵させ、茶葉が紅褐色に変わった頃合いをみて再び乾燥させ発酵をストップさせる）」を行い、仕上げの火入れ工程（こう焙）を経て生産される茶。 茶葉に含まれるポリフェノールオキシダーゼの作用により、カテキン類（タンニンと考えても良い）が酸化重合し、テアフラビン（橙赤色）やテアルビジン（赤色）などの赤色色素が出来る。また、この際いくつかの香気成分（花や果物のような香り）も生成される。
世界２０カ国以上で製造され、世界で生産される茶の８割を占める。
5. YELLOW TEA / Weakly post-fermented tea
(white-tea production process followed by weak oxidative fermentation )
The tea leaves do not go through withering unlike any other fermented tea production, and undergo heating treatment immediately. The heating starts at a low temperature; the temperature is slowly raised, and then gradually lowered, which causes a certain level of oxidative fermentation due to the enzymes the leaves contain. Then a process peculiar to the yellow tea, a subsequent fermentation process called Men Huang (literally, sultry yellowing) follows. This Men Huang is an enzyme-less oxidization process of polyphenols and chlorophyll that takes place under a high-temperature, high-humidity condition and without assistance of oxidizes or microbes, through which the leaves turn from green to transparent or yellow. The tea are classified into yellow bud teal (made from leaf buds only,) yellow young tea (made from young leaves,) and yellow grown tea (made from more grown leaves.) It has a long history and was mainly drunk by emperors from Tang dynasty to Qing dynasty; the production has been limited up to the present day. The manufacturing process of the tea was already complete by 18th century ; a novel "Dream of the Red Chamber"(Hong Lou Meng) by Cao Xueqin in Qing dynasty mentions this tea.
５. 黄茶
（弱後発酵茶：白茶と同じ工程を行った後、軽く酸化発酵させるもの）
弱後発酵茶。 発酵茶の中では唯一萎凋を施さずに加熱処理を行う。その際、低い温度から始め、徐々に温度を上げ、その後徐々に温度を下げることにより、茶葉の持つ酵素による一定の酸化発酵を行わせる。 その後、高温多湿の場所に置いて悶黄と呼ばれる黄茶独特の後発酵を行わせる。この悶黄は、酸化酵素や微生物の働きによらず高温多湿の環境でポリフェノールやクロロフィル（葉緑素）を非酵素的に酸化する行程で、これにより葉は緑から透明および黄色へと変色する。 芽だけでつくる「黄芽茶」、若葉でつくる「黄小茶」、少し大きくなった葉でつくる「黄大茶」に分類される。 黄茶は古く、唐代清代と皇帝を中心に飲まれており、今日も生産量は多くない。18世紀には製法が完成し、清代に曹雪芹が書いた長編小説『紅楼夢（こうろうむ）』のなかにも登場する。