The history of green tea begins around 5,000 years ago in China. Legend has it that it was Emperor Shennong (2737 BC) also written Shen Nong who discovered tea first. Originally, they were wild trees mainly in the mountainous region of southern China that were used to produce tea. The discovery of its tonic and refreshing effect, but also of its powerful medicinal properties, contributed to the development of its use mainly by Buddhist monks, but also by the Chinese upper class. The development and distribution of tea have been closely associated with issues of productive yield and conservation.
In the 4th and 5th centuries AD, tea was transformed in a totally different way today. The leaves were soaked after harvest, reduced in a chopper, then pressed into compact tea bricks (also called tea cake). The tea was then mixed and cooked with many other ingredients: rice, ginger, salt, orange zest, onions, etc.
During the Tang Dynasty (AD 618-907), this was how tea was used to be used. But there were also bags of crushed tea that were used against rheumatism. It was during this period that tea experienced its first major expansion.
A big boost in tea cultivation occurred during the Song Dynasty. It was during this period that the first powder of green tea was used for the tea ceremony and that this product began to become a product of daily consumption in this region of the world (China and Japan). This was then the creation of a second school of tea preparation: chilled tea . This form of preparation replaces the very refined tradition of cooking tea cakes which until then mixed tea with other ingredients.
In the 13th century, the achievements in terms of tea were destroyed and almost totally lost due to the conquest and domination of the Mongols. The latter were used to drinking fully fermented tea and had very little curiosity about tea cultivation under the Song dynasty. From this point of view, the Mongolian heritage was lasting. Green tea powder only reappeared centuries later and unfortunately only plays a minor role in tea culture in China, unlike Japan.
The current preparation and method of drying and stopping fermentation is later developed in the Ming Dynasty (1368-1644). The cultivation of green tea is still very closely linked to the history of China. It was first in the 16th century with the development of the tea ceremony, then even more from the 18th century, under the leadership of Japan with the development of mechanization, particularly in the agricultural sector that the cultivation of green tea takes on the scale and sophistication that we know today.
Green tea arrived in Japan in the 8th century, via Chinese Buddhist monks. These monks would have organized trips for this purpose. In addition, it seems that Japanese Buddhist monks have gone to study "the art of tea" in China. On their return, these monks would have participated in making the establishment of this culture possible in the archipelago. Buddhism and the particular properties of green tea have therefore played, and still play to this day, an important role in the development of this culture in the broad sense of the term. Originally, green tea was appreciated by monks for its medicinal properties, as well as for its toning and stimulating effects on concentration during long meditations. Thus, the philosophy of Zen Buddhism was influenced by “the path of tea” and counts among its followers tea masters who have profoundly influenced tea culture. In Japan, this drink has a symbolic value that goes far beyond the purely taste experience.
In Japan, the consumption of green tea was restricted to the highest social circles and revolved solely around its medicinal application. It was not until the 16th century that this situation gradually changed. In the absence of the “cultural brake” represented by the Mongol invasion in China, tea is gradually establishing itself as a pillar of Japanese culture and a staple of everyday consumption. An important part of this development is owed to tea master Sen No-Rikyu (1522-1591), one of the main founders of the tea ceremony. Green tea from the “Chemin du Thé” represents much more than a drink with a refined taste, but is an integral part of a philosophy of life integrating Zen Buddhism and refining its culture. The traditional preparation, salon and tea garden are symbols of spiritual improvement. Japanese culture has been heavily influenced by centuries of development, inspired by tea masters and Buddhism. This group has drawn its territory and marked its mentalities, probably as no other discipline has been able to do in its history. This particularly affects the ceramic industry, lacquering work, poetic lyricism and philosophy.
In 1738, a certain Soen Nagatari invented the method of rolling tea leaves after steam roasting. This method was a resounding success and is still used to this day in the preparation of Sencha. In 1835, the method of "shading" with rice straw was invented by Kahei Yamamoto and thus contributed to the creation of Gyokuro. But it was not until 1859, with the opening of larger-scale commercial ports by the samurai that tea became a daily staple in Japan. A little later, it developed and gained international scope thanks to the use of industrial machines.
The first shipment of tea arrived in Europe in 1610 via the Dutch East India Company, which held a monopoly on European trade with Asia. During the long sea journey of 6 months across the sea, the goods were severely damaged. However, it quickly became popular in the upper classes and with pharmacists (apothecaries) who sold it as a medicinal plant. In France, it arrives in 1636, in Russia, in 1638 and in England, in 1650. The prices of the tea remain then largely unaffordable for the popular classes, so that the tea will be for a long time the prerogative of the nobility and the rich. merchants.
In the 18th century, tea - despite its high price - was a resounding success in Europe and tea rooms flourished in all the metropolises.
All teas contain caffeine and polyphenols (antioxidants from the flavonoid family). Caffeine is a substance from the methylxanthine family present in many plants: coffee, cocoa, cola, guarana, mate, etc. Caffeine stimulates the nervous system and thus increases alertness and the capacity for mental concentration. It decreases appetite, slightly increases basal metabolism (the body's energy expenditure at rest) and stimulates urine production.
Tea is rich in polyphenols: catechins (in particular, epigallocatechin-3-gallate or EGCG), theaflavins, thearubigins, etc. These substances are antioxidants which can protect cells from chemical attack. In cultured cells, EGCG has shown a definite ability to inhibit the growth of several types of cancer cells. This effect is believed to be related to its antioxidant properties and its ability to inhibit an enzyme necessary for cancer cell growth, urokinase.
The effect of tea in preventing cavities could be linked to catechins, but also to its richness in fluoride.
From 60 mg in an adult, caffeine intake is accompanied by a stimulation of intellectual capacities and urine production. The effects of caffeine on appetite and basal metabolism are limited and disappear in people who consume it regularly. No long-term studies confirm lasting effects of caffeine or tea on weight loss.
Studies on the preventive properties of tea in the context of cardiovascular disease or cancer have led to contradictory results. These are mainly observational studies that show (or not) a lower risk of developing these diseases in people who spontaneously consume large amounts of tea. But the influence of other factors (diet or healthier life in general) is hardly ever taken into account. As part of the prevention or treatment of cancer, no study has clearly shown any benefit from consuming tea. Studies are underway in the United States to evaluate its action in the context of skin cancer.
Studies conducted on the effects of tea in preventing dental caries justify conducting larger studies to confirm the observed benefits. The other proposed uses for tea have not been scientifically evaluated.
