Authentic tea comes from the leaves plucked from two subspecies of the plant known as tea tree (Camellia sinensis /L./ Kunzte). The differences between specific types and kinds of tea are determined by the processing, the geographical location from which the tea comes and also by the quality and sort of material used for the production of such tea.
Production of tea is a highly intuitive process counting on year’s long experience and a more than thousand year-old tradition. Dividing tea into the categories by color has its roots in these facts but the causes lie in two groups of chemical processes. The degree of oxidation of the cellular juices and fermentation processes of the microorganisms present in the tea leaves are the crucial factors in defining the type of tea. Naturally every category has its own exceptions and it’s necessary to consider that this synthetic description serves only as a tool for orientation in the vast world of tea.
The leaves of the tea tree used for the production of green tea are, after the proper plucking and withering, exposed to a high temperature, usually on an iron pan or with a hot steam. This crucial step slows down the enzymatic activity inside the leaf and stops the natural oxidation of cellular juices. In case of some types of green tea this is followed by forming the tea leaves. In the end the leaves are dried to the ideal extent. In the production of green tea the leaves are kept whole and are not broken intentionally. Green tea is also called unoxidized tea. China, Japan and Korea are among the most important producers.
Yellow tea is produced very alike the green tea. After heat processing, the tea leaves are packed in small quantities into a wet cloth and let to mature. After some time, the leaves gain smell and taste, which is specific for the yellow tea. The only producer of this type of tea is China.
White tea is a product of the simplest processing method. After plucking, tea leaves are left to wither and dry slowly to the wanted degree. Traditionally the leaves are dried on the direct sun for approximately 2 or 3 days. The drying time depends on many factors such as: weather conditions, amount of the material and producer´s experience. In mass production, these conditions are eliminated by air-conditioned halls and mechanic machines. White tea is a little oxidized, which is a result of a slight and natural drying process. It is produced mainly in China, but in recent years India and Nepal have been also involved in the production.
Oolong is a tea type with the oxidation level just somewhere between the green and black tea. It is also called semioxidized tea. Tea leaves are left to wither and oxidize to the wanted extent after plucking. After that, they are sorted by grades, kneaded and baked. The last two stages are repeated several times depending on the type of oolong. Oolongs are more or less oxidized hence their color is closer to the green or black tea. China and Taiwan are among the most important producers.
Red tea, known more like black tea in Europe, is simply said whole leaf or broken. The production process of the whole leaf black tea is a kind of similar to the green tea but the oxidation processes continue to the full extent. Machines called rollers are used for speeding up these processes, by rolling the leaves and thus breaking the cell walls and releasing the juices on the surface to oxidize. Finally the tea is dried. Broken leave teas are used mainly for tea bags. The biggest producers of black teas are India, China, Kenya, Sri Lanka and Turkey.
The category of the dark tea includes a wide spectrum of different kinds from different locations. All kinds of dark tea have their post fermentation processes in common that change the chemicals in the tea leaves which are responsible for the taste and the aromatic and therapeutic properties of such tea. The post fermentation can be natural or artificial. Tea naturally ferments in specific conditions of moisture, air temperature, light and oxygen exposure and with the presence of microorganisms. The artificially speeded up fermentation is trying to produce ripe tea in a shorter period of time than the natural way which can take years by creating special conditions. Generally the dark tea is considered oxidized and fermented naturally or by a controlled artificial process. We can encounter the dark tea type mostly in China.
Pu'er tea belongs to the category of the dark tea type and we distinguish two different kinds: raw (ch. Sheng) and ripe (ch. Shu). In both cases, the production process is the same in the beginning stages: withering, stopping the oxidation processes by heat and drying. The leaves for Sheng Pu´er are steamed and pressed into various shapes. It is possible to drink such new tea but its taste is very rough and raw so freshly made Pu´er tea is left to mature – to post ferment. After some time the roughness disappears and the taste mellows – supposing good quality material was used. In the 1970s, Chinese researchers came up with a method of faster artificial post fermentation yielding the dark – ripe type of the Pu´er tea. Unlike the Sheng Pu´er, after the leaves are moistured, they are put in approximately one meter-high wet piles, covered and optionally mixed. The post fermentation is then promoted for one month or one and a half. After drying, the leaves can stay in the form of loose leaf tea or be steamed and pressed. The transformation in Shu Pu´er is not as radical over time as it is the case of Sheng, which is a newly produced tea kind and basically still green tea. The production of Pu´er tea is typical for the Yunnan province of China.
Therapeutic effects of tea do not depend strictly on the type of tea. Various kinds of tea differ mainly in taste and aroma. However, we could consider the overall content of positive substances to be very similar in tea as such. Tea contains many bioactive substances for example: catechins, theanin, caffeine, minerals and vitamins. Catechins are very strong antioxidants – they neutralize free radicals produced in organisms due to stress, bad environment and unhealthy lifestyle. Free radicals are responsible for the cell destruction and faster degradation and senescence of the organism. The tea tree is one of the few known plants that produce amino acid theanine. Theanine is responsible for stimulating the brain to produce the alpha waves (8-13 Hz), which are generally related to a relaxed and concentrated state of mind. Tea also contains significant amounts of Mg, Ca, K minerals and vitamins C, E and K.
Tea preparation depends exclusively on one´s taste and aesthetics. However, it is possible to recommend brewing time and the amount of leaves. Most of the tea types are easy to brew – we simply pour boiled water on app. one tea spoon of leaves and wait for one to one and a half minute depending on one’s taste. Only before we brew green tea types, we let the boiled water sit for about 5 to 10 minutes to cool down a little before pouring it on the leaves. We can brew one and the same tea many times until we like the taste. An old Chinese saying goes: Water is the mother and the vessel is the father of tea. These two facts are very important factors and concerning the tea preparation, they are equally important to the quality of tea itself.