Green tea, Black tea, and Oolong tea, tea is inseparable from our life. But do we really know what is tea?
Taiwan is definitely one of the most developed places in the world for tea cultivation, tea production, and high tea culture as well as public hand-cranked tea.
From the Queen’s fermented oolong tea to the most famous Oriental Beauty tea to the birthplace of pearl milk tea, Chun Shui Tang in Taichung, it is not too much to say that “tea” is the pride of the Taiwanese.
What is tea?
The tea we generally refer to is a beverage made from the leaves of the tea tree, which can be brewed directly with boiling water.
The tea set (Camellia sect thea. L) is divided into two species: the tea species (Chinese species) and the Pu-erh species.
Tea, coffee and cocoa are known as the world’s top three beverages.
According to research, the history of tea can be traced back to the Zhou Dynasty, with tea leaves as a tribute; the Western Zhou Dynasty as a sacrificial offering; the Spring and Autumn Period and the Warring States as food and medicine; and the Western Han Dynasty as a major commodity.
In the Western Jin Dynasty, tea was even recorded as a soup and drink until the emergence of steamed green tea in the Tang Dynasty, which marked the birth of the first tea in China in the true sense – green tea (there is still a theory that white tea was the first to appear); followed by the invention of steamed green loose tea in the Song Dynasty.
The Ming Dynasty created Green tea, Yellow tea, Dark tea, and Black tea, and the Qing Dynasty created white tea and Oolong tea so that the six major tea types were basically finalized and complete.
What is tea? – six types of tea
Where does the term “six types of tea” come from?
The six tea types were named based on the craftsmanship of their predecessors and the characteristics of each tea group.
The six types of tea are divided into Green tea, Yellow tea, Dark tea, White tea, Oolong tea, and Black tea.
Such naming not only preserves the scientific common names created by the laboring people and makes the classification commonplace, but also makes it easier to distinguish the quality of different teas from simple to complex and from less to more in the intrinsic changes of tea leaves, while the classification will be more systematic and scientific
For example, the basic process of white tea is withering and drying, while the basic process of green tea is withering, greening, twisting, and drying.
This is how the six tea types are classified from different processing techniques.
Under the category of white tea, it is subdivided into white hairs and silver needles, white peony, Gongmei, Shoumei, etc. This embodies the systematic nature of the classification, from simple to complex, from small to large.
It can also be said that all teas must be classified into one of the six major tea categories, and the reprocessed teas are also classified on the basis of the six major tea categories.
For example, jasmine tea is made with green tea and jasmine flowers, so it is essentially the same as green tea, but the difference is that it has a distinct jasmine fragrance, which is not present in green tea.
What is tea? – six types of tea
What is the nature of the classification of the six major tea types?
It is undeniable that the six major tea types are indeed classified according to different processing techniques. After spending some time reading Wang Mingxiang’s book (Wang Mingxiang, the founder of the tea brand “Seven Thirty Tea Hall”, wrote this book “The Hidden Knowledge in the Taste of Tea: The Hidden Mystery of Substances in the Taste and Taiwan Tea Stories, My 10 Years of Tea Learning Notes” to share with you what tea is from various perspectives.
The different processes are only the form of differentiation, while the quality characteristics of different tea types are their appearance. The most fundamental is the result of the biochemical reaction of the substances in the tea leaves during the processing and the final presentation of these substances with different contents and ratios, and the generation of new products.
The different tea types are accurately classified on the basis of the different processes combined with the order of the flavanols (catechins) content.
Quoted from “The Theory and Practice of Tea Classification”, 1979
For example, if we compare green tea with black tea, the processes of green tea are withering, greening, twisting, and drying.
The process of black tea is withering, twisting, fermenting, and drying.
In their respective qualities, green tea tastes fresher and sweeter, with the characteristics of “green leaves, green soup, and green bottom”, and has a tender or roasted aroma; while black tea tastes more exciting and thicker than green tea, with the characteristics of “red leaves, red soup”, and has a strong floral and fruity aroma.
In essence, the composition and proportion of their inclusions are different: after green tea is killed, the tea polyphenols are not oxidized and basically retained, so the green tea soup color presents the color of chlorophyll and other non-processed pigments (anthocyanin); while black tea is fermented so that most of the tea polyphenols oxidize into the theaflavin, theaflavin and other processed pigments, and also produces a large number of aromatic substances, so black tea soup will be orange-red. The black tea broth will be orange-bright red, and the aroma will be stronger and different from green
For more info on the six tea types
: Do you know the characteristics of the 6 major tea types?
What is tea? – Fermentation of tea
The scientific knowledge to share with you. What is the “fermentation” of tea?
It is worth noting that the concept of tea fermentation is not the same as the fermentation of beverages or foods such as wine and milk.
The “fermentation” of tea refers to the process of enzymatic oxidation of the polyphenols (catechins) in tea leaves, and there are actually no microorganisms involved in the reaction.
The term “fermentation” of tea first appeared in Japanese research and has been used ever since, while the term “post-fermentation” was first introduced by Wheat, which refers to the process of degrading and transforming the biochemical components of tea leaves by microorganisms.
-Quoted from “The Concept and Substance of “Fermentation” in Tea Making”, 1963
Different types of tea can be classified according to the degree of fermentation, which is in essence based on the degree of oxidation of catechins.
The oxidizing enzymes contained in the tea leaves are used to further oxidize the polyphenols in the leaves and the oxygen and O2 in the air to produce a variety of tea colors, aromas, and flavors, which is called “pre-fermentation” or “enzymatic fermentation”.
After the process of “fermentation”, yellow tea is “boiled” dark tea is “piled” with the effect of humidity and heat, or raw tea is stored for a long time to promote the fermentation of tea leaves by microorganisms in the natural environment, which is called “Post Fermentation” or “Non-Fermented Fermentation”.
What is tea? – Fermentation of tea
What is tea? – Classification of Tea
Therefore, according to the different fermentation levels, there are the following classifications.
Unfermented tea: Green tea
Lightly fermented tea: White tea, Yellow tea (formerly lightly fermented tea)
Semi-fermented tea: Oolong tea
Fully fermented tea: black tea (post-fermented tea)
What is tea? – The fermentation process of tea
Where does the term “six types of tea” come from?
1. Fresh leaves – one of the fermentation processes of tea
The buds, leaves, and young stems of Camellia sinensis L.O. kunts are harvested from the tea tree of the Camellia sinensis genus, which is used as the raw material for processing various types of tea leaves.
Fresh tea leaves: After the leaves are picked and before processing into various types of finished tea, it is necessary to ensure that the fresh leaves are kept in a fresh state during transportation and to avoid squeezing, accumulation of heat, excessive collision damage to the leaves, etc. to prevent premature reaction of the substances contained in the fresh leaves.
2. Tea leaves – the second of the tea fermentation process
A product that is made from fresh leaves and processed by a specific process without any additives for people to drink or eat.
Yunnan Red Golden Needle (black tea): Tea must be made from the Camellia sinensis group of plants in the Camellia sinensis family. Products such as “rose tea” and “chrysanthemum tea” that do not contain tea leaves are not tea in the true sense of the word, but “non-tea of tea”.
3. Withering – the third of the tea fermentation process
The process of wilting and dispersing water by spreading the fresh leaves evenly under certain temperature and humidity conditions.
Withering (Lingtou single bush): Different tea types require different withering times, in addition to controlling the temperature of withering and the moisture content of the leaves.
If withering is too early, the tea broth will taste light; if withering is too long, the tea broth will taste bitter. At the same time, the green odor of fresh leaves will be dissipated and transformed into a clear aroma during the withering process; the hydrolysis of some glycosides will free out the glycosides with aromatic compounds, forming various aromas
4. Greening enzyme inactivation – the fourth of the tea fermentation process
The process of inactivating or passivating the enzymes in the fresh leaves by applying a certain temperature.
Different killing green methods: The main function of killing is to inactivate or passivate the enzymes in the tea leaves at high temperatures, and to terminate the enzymatic reaction inside the tea leaves. 80℃ is the critical point of inactivation for most enzymes, so the temperature should be above 80℃ when killing green.
The killing green process will be accompanied by the production of certain aromas, and the aromas produced by different killing green methods are different.
For example, frying in a pot will result in a Merad reaction and a caramelization reaction, resulting in aromatic tea leaves and the color of the tea base, brownish green in dry tea, and the aroma is mainly baking aroma; while steam firing is beneficial to the degradation of substances, the color of tea leaves is more emerald green, and the aroma is mainly fresh and tender.
5. Fine manipulation – the fifth of the tea fermentation process
Under the action of mechanical force, the fresh leaves are partially damaged at the leaf edges, resulting in the partial oxidation and polymerization of the polyphenols contained in them, producing green leaves with red edges.
The “green leaf red edge” after fining manipulation: fining manipulation is a unique process for Oolong tea, the essence of which is also to make the catechins develop an enzymatic reaction and turn red, but the degree of fermentation is not high, usually only the edges of the leaves will turn red.
There is also a kind of oolong tea with a higher degree of fermentation – Oriental Beauty, which has a rich floral and fruit honey aroma. However, the fermentation time is longer, and a better qualityoolong tea needs to be fermented about 6~8 times, with each time taking about an hour.
6. Heaping for yellowing – the sixth of the tea fermentation process
The process of heaping for yellowing of the fresh leaves after the fermentation, kneading, or initial roasting, so that they will gradually turn yellow under the effect of humidity and heat.
It is not the oxidation of the enzymes in the fresh leaves, but the accumulation of the leaves after the killing green process, the change of catechins and the degradation of chlorophyll through humidity and heat, and the decomposition of microorganisms.
These reactions are very slow, so “when the green color changes to yellow”, the boiling yellowing can be stopped.
In addition, under the effect of humidity and heat, the sugars and proteins in the fresh leaves will be hydrolyzed to produce simple sugars and amino acids, which contribute to the taste and aroma of the finished tea.
7. Fermentation enzymatic reaction – the seventh of tea fermentation process
Under certain temperature and humidity conditions, the fermentation process of fermenting the fresh leaf contents, which is dominated by the enzymatic oxidation of polyphenols, results in leaf reddening.
Black tea fermentation: fermentation is the process of oxidation of catechins into other products through the oxidation enzymes in the cells of fresh leaves. The fermentation of black tea is mainly oxidized into theophylline and other pigments; the chlorophyll in the whole fermentation process is basically degraded into brown demagnetized chlorophyllic acid, chlorophyll alcohol, and methanol.
Fermentation also needs to pay attention to the temperature and water content of the leaves. When the water content of the leaves is lower than 68%, the continuous water loss of the leaves will reduce the enzyme activity; while a lower temperature (20℃) can ensure higher enzyme activity.
8. Pile – the eighth of tea fermentation process
Under certain conditions of temperature and humidity, the process of slow change of the tea leaves through the accumulation of its inner substances.
Pile: Pile is also known as“post-fermentation”, which is the process of degradation of tea leaves through the action of enzymes by microorganisms through the action of heat and humidity.
Among them, polysaccharides are hydrolyzed into monosaccharides, proteins are hydrolyzed into amino acids, catechins are changed from esters to non-ester catechins or further oxidized into other pigments, and other reactions, etc.
For example, the “golden flower” in black tea, there is a kind of microorganism called “Clostridium perfringens”that grows in the process of stacking, which is the “golden flower”(spores of Clostridium perfringens) in Fu-brick tea.
It is a kind of fungus that is beneficial to the human body and has a certain effect on improving the immunity of the human body and regulating intestinal flora.
We can take the initiative to add this fungus to the process of fermentation through artificial means, so it is not unusual to see “golden flowers“ in the fermentation process of tea.
If we do not take into account the picking conditions, tea varieties, seasons and places of production, the tea leaves will consume more “tea polyphenols” due to the deepening of fermentation during tea production. Therefore, the higher the fermentation, the more astringent the tea leaves become, the sweeter the tea leaves become, and the color and aroma of the tea leaves become more intense and clear.
“Theophyllic acid” also participates in the fermentation and oxidation process totransform more tea aroma substances, therefore, the higher the fermentation level of tea, the stronger the aroma. Caffeine, which has a bitter taste, is not involved in the fermentation of tea leaves, therefore, the bitterness will not change depending on the fermentation level.
In the future, when friends or foreign executives come to Taiwan on business trips to bring tea back home or for family gatherings, you can introduce to everyone what tea is.
It is definitely worthwhile to spend some time learning about tea and the six tea types, the fermentation process, and various tea cultures.