The tea plant (Thea Sinensis) is an evergreen plant of the Camellia genus and is also known as Camellia Sinensis. It is further divided into two main species, Camellia sinensis var. sinensis from native of China and Camellia sinensis var. assamica from native of India’s north-eastern province of Assam. The small leaf variety, known as Camellia sinensis, thrives in the cool, high mountain regions of central China and Japan. The broad leaf variety, known as Camellia assamica, grows best in the moist, tropical climates found in Northeast India and the Szechuan and Yunnan provinces of China.
White tea, yellow tea, green tea, oolong, pu-erh tea and black tea are all harvested from the same plant, but are processed differently to attain varying levels of oxidation. Kukicha (twig tea) is also harvested from Camellia sinensis, but uses twigs and stems rather than leaves. The specific variety of tea plant and the way the leaves are processed after harvesting determine the type of tea that is created.
Today, tea bushes are commercially grown in over forty countries around the world and thrive in countries closer to the equator with tropical climates. The best plantations can be found at altitudes of between 1,200 metres to 1,800 metres (4,000 feet to 6,000 feet) above sea level, where the plants are protected from too much direct sunlight or cool air by mists and cloud. This allows the new buds and leaves to develop and grow more slowly, which results in more flavour. Thus, the term ‘high-grown’ refers to teas cultivated above 1,200 metres (4,000 feet).
Processed Tea Variants
It was thought at one time that green and black teas were made from different plants. In fact it is only the different plucking and processing methods that produce the different types – green, black, oolong, white, yellow, Pu-erh or scented. Many different varieties within each category result in hundreds of teas from all over the world. The tea leaves are plucked as the new shoots or “flush” are beginning to grow. These tiny young shoots and their thin, unopened buds produce the most delicate and flavourful teas. Picked and processed only by the hands, these delicate young leaves go into the making of a premium tea.
Different processing methods produce different varieties of tea. Fermentation is one of the key factors for differentiating the varieties of tea. Broadly speaking, tea can be categorised into non-fermented, semi-fermented, full-fermented, and post-fermented tea. The most crucial part, what defines the categories of tea, is Oxidizing. Oxidation occurs when the enzymes in the tea leaf interact with oxygen, after the cell walls are broken apart. This can happen quickly, through rolling, cutting, or crushing, or more slowly through the natural decomposition of the leaf. Although the level of oxidation and fermentation is different, all tea varieties go through several key production steps: picking, withering, pan firing, rolling, fermentation, roasting, and sieving.
How tea makers control the process of oxidation and fermentation in harvested tea leaves makes a world of difference to the kinds and quality of the tea produced. This includes not only the taste, colour, aroma, and nutrition values of the tea, but also the lifespan of the tea. For example, green tea, which is non-fermented, lives a much shorter lifespan than the post-fermented Pu’er tea, which can be kept for decades.
Tea is traditionally classified based on the techniques with which it is produced and processed. Impurities like yellow leaves, old leaves, and stalks have to be picked out from the harvest. After picking, tea leaves have to go through a withering and pan firing process. Withering means spreading out the plucked leaves to transpire. The aim is to remove moisture and promote enzyme activity to facilitate chemical changes within the leaves. This process is necessary for the production of oolong, white, and black tea, where oxidation is necessary to produce the chemical compounds that create their flavours and characteristics; and the presence of enzymes promotes and facilitates such oxidation.
The rarest of the different classes of tea, yellow tea is only produced in China, in the high mountains of Hunan, Zhejiang and Sichuan provinces. It is only grown on the mist-covered mountain of Jun Shan Island, and they are all made during the early Spring season.
Yellow tea takes its name from its straw colored liquor. It is famous for their smooth, savory, sweet unique fruity and fermented aromas. It is closely related to green tea and has similar antioxidant health benefits with green tea but with a smoother taste. Means it is easier on the stomach than green tea. The production process is similar to green tea, but with a unique additional step called men huan, or “sealing yellow” which is a slow oxidation process of tea polyphenols such as catechin. The plucked leaves are exposed to wither for a somewhat longer time than those used for green tea, so that they lose part of their moisture. They are then fired or heated either in a wok or with hot air. Then the still quite moist leaf material is piled up, wrapped in special cloth, a step that is repeated several times over a period of up to three days, gently oxidizing the leaves and dried in a wok, with hot air or on charcoal. This smothering process pulls the aromas back into the buds and creates a more aromatic and mature tea, free of the “grassy” taste and astringency found in many green teas. Besides aromas similar to those of green teas, yellow teas have a typical, slightly smoky, but also a mellow and sweet note. Its aroma is delicate, with hints of chocolate and coffee. The infusion is variably strong depending on every individual kind.
Often made from the leaves of wild growing tea bushes, that often grow in inaccessible terrain, the range of sorts is very limited and there are only small quantities available. Yellow tea is best placed between green and Oolong. Pickers gather only the bud by breaking it from its stem with a twist. It takes 60,000 of these carefully harvested buds to yield just one kilogram of Jun Shan Yin Zhen. Because its production is difficult and time-intensive, yellow tea has primarily been consumed by locals. As the demand for easier-to-make green tea has increased in the West, many have abandoned the production of yellow tea in favor of green. Today, few tea masters are alive with the skills required to make yellow tea.
White tea comes from the buds and immature tea leaves that are picked shortly before the buds have fully opened. The name “white tea” derives from the fine silvery-white hairs on the unopened buds of the tea plant, which gives the plant a whitish appearance. The beverage itself is not white or colourless but pale yellow and light to the taste.
The leaves come from a special varietal tea bush called Narcissus or chaicha bushes. According to the different standards of picking and selecting, white teas can be classified as Yin Zhen Bai Hao (Silver Needle), Bai Mu Dan (White Peony), Gong Mei (Tribute Eyebrow), and Shou Mei (Noble, Long Life Eyebrow).
White tea is simply plucked and allowed to wither dry. The leaves and buds are allowed to wither and dry in natural sun. Fragile buds must be carefully monitored as they are withered and dried. If the weather isn’t cooperating, the leaves may be put into a gentle tumble dryer on very, very low heat to assist (tea waits for no one), but the leaves are not rolled, shaped, etc. Only lightly oxidized, white teas never undergo fermentation or roasting processes, so they retain a much greater subtlety of flavor and an abundance of tea’s natural antioxidants. Because white tea is unprocessed and unfermented, it retains higher levels of polyphenols. This gives white tea an advantage over other tea varietals when it comes to antioxidants. This labor-intensive process produces a delicate and faintly sweet tea with a light grassy flavor
The highest-quality white tea are Silver Needle and White Peony, both of which have various grades and are primarily produced in the Fuding and Zhenhe districts of Fujian, China. Silver Needle is carefully hand selected from the tender fleshy sprouts of the “Big White” or the “Narcissus” tea bush. If the buds are selected with two leaves intact, then the resulting selection will be made into White Peony tea. The leaves and other material left over from the selection of Silver Needle and White Peony will be processed into Noble, Long Life Eyebrow. Gong Mei is made from “chaicha” bushes and is processed slightly differently than other white teas. Both Gong Mei and Shou Mei are considered lesser forms of white tea compared to Yin Zhen Bai Hao and Bai Mu Dan.
When brewed, white teas give hardly any color and infuse a very delicate flavor into the water. This tea is only harvested two days a year. With small yields and high demands, this tea remains one of the world’s most rare teas.
All teas offer a world of health-inducing benefits, but green tea is most widely known for its powerful polyphenols, which are strong antioxidants. Like all tea, green tea is a varietal of the evergreen Camellia sinensis bush. It is the oldest way of tea production, in the form of leaf tea however it only dates back to the 12th century before that, leaves were steamed and pressed. Roasting and baking has been known since the 16th century.
Green tea is made from more mature tea leaves than white tea, and may be withered prior to steaming or firing. The very most green teas are plucked during spring (March/April), but there are also harvests during summer. Unlike black and oolong teas, it is not oxidized. Depending on the kind and quality of the tea bushes, two leaves and a bud, one leaf and the bud or only the bud are plucked and laid out in the shade indoors or outside for a short time to lose some of their moisture. The leaf material is heated up strongly then. This process is called Sha Qing in Chinese, which means “killing the green”, and deactivates all the enzymes in the leaves, thus preventing any oxidation and fermentation for a certain time. It can be done in four different ways: drying in the sun, steaming (water steam), baking (with hot air) and roasting (in the wok), and rolling.
Green teas always have a very present tart and slightly bitter note to them, and especially cheaper qualities can turn over the really bitter end of the taste spectrum. Although they are also rich in catechins, green teas may have different catechin profiles than white teas.
A brewed green tea is typically green, yellow or light brown in color, and its flavor profile can range from grass-like and toasted (pan fired) to vegetal, sweet and seaweed-like (steamed). If brewed correctly, most green tea should be quite light in color and only mildly astringent.
Like all teas, Oolong starts out as a variety of the evergreen Camellia sinensis bush. And like our other fine teas, it is a result of how it is cultivated, where it is grown, elevation and climate and most of all, how it is processed. The production of Oolong teas probably emerged around 1500 on the Wudong mountain in Phoenix and came over Anxi to Wuyishan and Taiwan. But unlike most teas of the world, oolong is a relative newcomer, developed in Formosa (Taiwan) in the mid-nineteenth century. Its name means “black dragon” in Chinese in reference to the long, twisted leaf forms.
In order to obtain big leaves they are plucked quite late in the season. Depending on the region there are harvests during spring and autumn/winter. In difference to other types of tea, it is not “two leaves and a bud”, but a stem with three to five big leaves on it which is plucked. In the case of the ball-leaved Oolong the stem is being processed along with the leaves.
Oolong gains its alluring character through a meticulous, multi-step process that begins with withering and a brief oxidation in direct sunlight. As soon as the leaves give off a distinctive fragrance often compared to apples, orchids or peaches, this stage is halted. They are loosened up by shaking, which partially breaks up the cell structure. This enables the leaf substances to come into contact with the leaves’ enzymes, which start oxidising the former by connecting them to the oxygen of the air. After the shaking, the leaf material is thus piled up in portions and left to oxidise/ferment over night, while the shaking is repeated with increasing intensity. Depending on how often the leaves are shaken, the thickness of the piles, time, temperature and moisture, leaves oxidise more or less intensely. As all Oolongs are oxidised (fermented) with a degree of ten to fifty percent they are also called “half-fermented teas”. The leaves are rolled, then heated in rolling machines and heated rotary drums to halt oxidation when it is about half way between black and green tea. The caffeine content is also midway between black and green teas. Sha Qing, “killing the green”, which means again the complete deactivation of enzymes takes place. However, enzymes are not totally deactivated, which means that the tea is still alive and changes over time when stored. Finally, Oolong teas are dried with hot air, fire or charcoal. Roasting the tea over charcoal can be done immediately after the tea has been dried or even later. Depending on the heat the tea is not only dried here, but also changes in taste.
Black tea (Wilted, sometimes crushed, and fully oxidized):
China is known as the birthplace of black tea. Called Qi Hong or Red Tea by the Chinese because of its coppery-red color, Black tea is the second most popular tea in the world. It is believed that black tea was discovered when the Chinese started fermenting tea leaves in order to extend the storage life of tea. Fermentation produced an oxidized, darker version of the leaves, which became known as “black tea”. It is a more oxidized version of white, green or oolong teas and tends to have a stronger flavor than other tea types.
Today, many varieties of black tea are produced all over the world including China, Taiwan, India, Sri Lanka, and Nepal. Basic making procedures of black tea include withering, rolling, fermentation, and drying. Among them, fermentation is the most significant process of making black tea. It defines the quality of the tea. Meanwhile, plenty of healthy substances are produced during fermentation, which are important to the health benefit of black tea. Also fermentation is the reason why people who cares for health loves black tea.
The manufacturing methods and varieties of black tea vary enormously from country to country and sometimes even from region to region within the same country. But no matter the overall differences in manufacturing from one country to another, there are always four basic stages involved in the production of black tea: withering, rolling, oxidation (sometimes erroneously referred to as fermenting or fermentation), and firing (drying).
There are two major types of processing methods for manufacturing black tea-orthodox and CTC (cut-tear-curl). Orthodox black teas are loose leaf artisan made teas in a variety of different styles and types available from various countries around the world. The picked leaf undergoes a full fermentation process composed of six basic steps.
The basic stages of manufacturing tea begin with withering. The leaves are exposed to hot air for several hours in order to reduce their water content by 50% to 60%. This step starts to free up the enzyme responsible for oxidizing the leaf (fermentation). It also softens the leaves, preparing them to undergo subsequent operations without breaking. The leaves must not be broken or bruised (except for oolong). The tea leaf is then soft and supple and ready for the next stage, rolling.
The rolling step starts the oxidation process by breaking the leaf’s cells and releasing the natural essential oils and chemicals. This is done with a rolling machine that presses and twists the leaves, rupturing the inner cells. The aroma of the tea depends on these essential oils. After this first rolling, smaller pieces of leaf are sifted out and larger pieces are placed back in the rolling machine for a second, and some- times even a third rolling. Sometimes the leaf is put through a rotor-vane machine that minces, twists, and breaks the leaf into even smaller pieces than the orthodox rolling machine, maximizing production of the smaller pieces of leaf for broken grade tea.
The next step is fermentation that cause the chemical reaction of the leaves and their components (polyphenols) by spreading out in thin layers in cool, humid air and left to oxidize for 20 to 30 minutes or more, depending on climate and air temperature with air, humidity and heat. It is during this stage that the leaf begins to develop the recognizable aroma and flavor of black tea, darkening in color, and developing compounds called theaflavins and thearubigins, belonging to a group called polyphenols. If this step is stopped too soon the tea is greenish and can have a metallic after-taste; if it is fermented too much it becomes sweetish and loses both quality and aroma.
The final step is to stop the oxidation process and dry the leaf. The characteristics of the tea become fixed at this stage (colour of the leave turns black). Drying the leaves in the oven stops the fermentation process. If the leaves are not dried enough, the tea may be attacked by mould. If they are dried too much, the result is a tea without aroma since the aroma-carrying elements remain largely insoluble. Finally, the leaves are separated by size or grade. This operation also cools and ventilates the leaves.
Post-fermented/ Pu-erh tea
Pu-erh is usually a very highly fermented tea that is produced primarily in the Yunnan Province of China. It is very unique type of tea which tastes better as it ages. Pu-Erh tea is another of China’s great treasures and has only recently been discovered in the West. It is unlike any other tea in the world but Westerners can appreciate its similarities to fine wine, with which it shares many attributes and is used as medicine. Only aged tea that comes from Yunnan province can be called Pu-Erh tea. Like the great wine regions of the world, Pu-Erh Tea production is highly regulated to ensure the highest quality and authenticity.
Pu-erh tea is made from the leaves and stems of the Camellia sinensis plant. This is the same plant that is used for making green, oolong, and black teas. Though the same source plant is used, the different teas are made by using different processes.Green tea is not fermented, oolong tea is partially fermented, black tea is fully fermented, and Pu-erh tea is post-fermented. This means Pu-erh tea’s processing includes both fermentation and then prolonged storage, or “aging,” under high humidity. Pu-erh tea that is aged for a longer period of time is supposed to taste better. However, it can also smell musty or taste stale because mold and bacteria will sometimes attack the tea during the long aging process.
The leaves are grown and harvested in counties along the Lancang River. Each estate produces its own special type of leaves, ranging from the tips and strong stems grown on estate cultivated plants to the highly prized large and soft, silver leaves picked from plants and trees that grow wild on the hillsides. Some trees are said to be over 1,000 years old. The leaves picked from these old trees are referred to as “wild arbor”. The leaves are harvested and sent to Pu-Erh City where each manufacturer blends the leaves to make their own unique and time-honoured recipes
Pu-erh tea or post-fermented tea is a particular type of producing teas in which the tea leaves undergo a fine process of microbial fermentation after the tea leaves are dried and rolled. This process is a Chinese specialty and produces tea known as Hei Chá, commonly translated as dark, or black tea. The best known variety of this category of tea is Pu’er from Yunnan Province, named after the trading post for dark tea during imperial China. The name of the tea is pronounced approximately as “pu’ar”.
Pu-erh is typically made through two steps. First, all leaves must be roughly processed into maocha to stop oxidation. From there it may be further processed by fermentation, or directly packaged for several months to many years. The exposure of the tea leaves to humidity and oxygen during the process also causes endo-oxidation (derived from the tea-leaf enzymes themselves) and exo-oxidation (which is microbially catalysed). The tea leaves and the liquor made from them become darker with oxidation. Thus, the various kinds of fermented teas produced across China are also referred to as dark tea, not to be confused with black tea.
The pu-erh tea consists of two completely different categories. One is called “Raw pu-erh Tea” and another is “Ripe pu-erh Tea”. While the tea undergoes fermentation, the mold produces a certain organic acid that causes the pH of the tea to reduce resulting in a complete fermentation within a much shorter duration. Hence, the colour of the tea leaves changes to dark brown and produces a mellow taste with thick body. The good quality ripe pu-erh gives out a flavour like dried Chinese dates.
Basically, raw pu-erh tea-making process is similar to that of green tea. But it is not identical. Firstly, the plucking standard is different. For pu-erh, normally one bud and three to four leaves are plucked which is just like oolong tea. On the other hand, green tea is usually made of single bud and one or two leaves, but sometimes it is made of single buds. In fact, for further maturation of pu-erh, the third leaf plays an important role in contributing to the floral note or fruity flavour. As compared to the first bud or second leaf, the third leaf has stayed much longer on the tree; hence the third and fourth leaf is very rich in polyphenols and minerals. In order to get a strong flavour and aftertaste, the third leaf is essential.
The plucked tea leaves are fried in a pan in order to deactivate enzymes. During the process of making pu-erh tea, pan-frying process does not completely deactivate enzymes, but some enzymes still remain alive. The tea leaves are not dried using the hot air, but it is dried under the sun. Sunshine drying process assists the fermentation. Sunshine drying does not instantly increase the temperature of tea leaves which causes the remaining enzymes to be active. During sunshine drying process, the tea leaves are spontaneously fermented and produce a typical flavour of pu-erh tea.
For freshly-made pu-erh, the tea leaves are still green. Therefore, if the pu-erh is kept for a longer period of time, the tea leaves will become yellow. The leaf of well-kept pu-erh tea does not really turn brown in colour. If the storing environment is well managed during the storage period, the tea leaves will remain yellow. The freshly-produced pu-erh tastes similar to that of green tea. With moderate oxidation during storage, its characteristics become similar to that of white tea. With further oxidation, the characteristic of the tea turns slightly closer to oolong tea, and finally it becomes similar to black tea. Being able to discover changes in various taste and flavours found in the product of different storage years is the utmost satisfaction of indulging pu-erh. From the same identical batch of pu-erh, the flavour also differs depending on the storage method.
During the production of ripe pu-erh tea, the initial step is to process the fresh tea leaves into raw pu-erh which is not immediately transformed into ripe pu-erh tea but will undergo a process called post fermentation.
Firstly, the raw pu-erh tea is piled on the ground and water is sprinkled over the tea to initiate the microbiological fermentation. The moist tea leaves are then covered with sheets in order to maintain the humidity. In this stage, bacteria such as actinomycete, will concur and nurture the fermentation process resulting in an increase in temperature that could reach up to 70-80 degree Celsius (peak of fermentation) within the pile of tea leaves. Once a week, the sheets will be opened to mix and even out the moisture within the tea leaves. Several weeks later, when most of the substances are converted, the fermentation process is stopped. Naturally, the temperature also decreases.
The tea leaves are then spread over the floor with the thickness about 200mm. During this process, yeast and mold dominates the fermentation causing the tea leaves to gradually lose their moisture, simultaneously, the appearance of mycelium of mold occurs on the leaves. This process has two objectives which are the drying of tea leaves as well as yeast and mold fermentation. However, if the tea leaves are piled too thick or dried using hot air, the tea flavour will diminish.
During the secondary fermentation, due to the coagulation caused by the mycelium of mold, lumpy tea leaves are formed. The size of cha-tou is approximately 10-40mm whereas the shape is inconsistent. This is called “cha-tou” in Chinese which literally means the “tea head”. Once the cha-tou is formed, the moisture trapped within the leaves will undergo a certain fermentation or maturation that will produce a dried-fruity flavour which many manufacturers cherish. Therefore, it is one of the most expensive and limited tea among ripe pu-erh teas.