According to the degree of fermentation, tea is divided into fermented tea, green tea, black tea and Pu'er tea.

Many kinds of tea come from the same plant-camellia. Different kinds of tea are the result of different tea-making processes.

The degree of tea fermentation is one of the key steps in the process of making tea. It refers to how many enzymes are allowed to oxidize tea before drying. The oxidation process can be prevented by baking or steaming before the leaves are completely dry. After fermentation, the originally dark green leaves turned reddish brown. The longer the fermentation time, the darker the color. Depending on the time of baking and the degree of fermentation, the aroma can be floral, fruity and malt.

One way to classify tea according to the degree of fermentation is:

Unfermented tea

Semi-fermented tea

Fully fermented tea

Post-fermented tea

During the fermentation process, the tea is placed in a spacious, cool, damp and dark room, where they are laid flat on a surface about 10 centimeters thick. The most common is to use aluminum or wood to avoid chemical reactions between tea juice and the surface. An ideal combination of low temperature about 15 degrees Celsius and high humidity about 90%. Fermentation can last from 45 minutes to several hours.

Non-fermented tea and light fermented tea

Unfermented tea includes white tea with an oxidized state of up to 10% and some green tea, which has not gone through the fermentation process or has passed a weak degree. Ancient tea masters noticed that preheated tea leaves did not ferment or oxidize. This is why these varieties of tea can maintain their natural colors and characteristics. Unfermented tea has long been regarded as a therapeutic drink surrounded by its own kind. Its therapeutic effect was discovered as early as the 19th century, when it was equipped with a large number of useful ingredients, which were almost completely preserved because it was not fermented.

Leaves are usually collected before 9 a. M., and then the raw materials are dried and sorted. Then heat-treat the tea to remove the bitterness and stop fermentation. Most green tea stops fermentation by baking, and a few green tea stops fermentation by steaming. In addition, as a rule, leaves are given some form; finally, the tea is dried, classified and ready to drink.

The tea retains a lot of its original taste. Green tea falls into this category. They are not actually fermented tea. White tea undergoes very slight fermentation during withering. Sometimes these unfermented and very lightly fermented teas have the scent of jasmine petals, giving the tea jasmine aroma.

Examples of unfermented tea and slightly fermented tea: green tea, jasmine green tea, yellow tea.

The color of these teas is yellowish green and has fresh natural aroma.

Semi-fermented tea

Tea fermented by 10% to 80% is called semi-fermented tea (moderate). Tea brewed with semi-fermented tea has a yellowish to brownish yellow color and rich aroma. These teas can be further divided into three categories according to the degree of fermentation:

Light (10%-20%): Jasmine tea (jasmine Puchong flavor), Puchong tea, Meishan Luzhou-fragrant oolong tea. These teas are rich in aroma, clear and golden in color.

Medium (20%-50%): most oolong tea, Dongding oolong tea, Tieguanyin. The brown color is light green brown, the taste is full and the aftertaste is sweet.

Heavy (50%-80%): Oriental Beauty Oolong Tea, Hsinchu Red Oolong Tea. These teas have red and orange colors and fruity aromas and flavors.

Fully fermented tea

As a result of fermentation, some insoluble substances in tea plant tissues become soluble and soluble substances. These substances give taste, smell and color to tea. The longer the fermentation process goes on, the stronger they become.

The fermentation time is related to the temperature. The higher the temperature, the faster the fermentation. But it is also dangerous that the temperature is too high and too low, and it takes much longer than usual to ferment at too low temperature. The optimum temperature is-+ 22-26 degrees. The process stops when the temperature is below + 15 degrees Celsius. When the temperature is higher than + 30 degrees, some of the soluble substances that give power to the tea will become insoluble substances, thus worsening the quality of the tea.

Black tea is completely fermented. The leaves of black tea are dark red with the sweet smell of maltose.

For example, Sun Moon Lake black tea, Yuchi black tea, Assam black tea.

Post-fermented tea

The tea that stops processing after fermentation and then ferments again is called post-fermented tea.

Example: pu'er tea. It has a very special aroma, color and taste depend on the degree of processing.