Dark tea undergoes external microbial Fermentation, which involves not only the enzymatic reactions of the leaves themselves but also the assistance of external microorganisms. Professor Liu Zhonghua notes that in English descriptions, the process for Black Tea (red tea in Chinese) is referred to as “oxidation,” while dark tea truly undergoes “fermentation.”
The wet-piling fermentation is a unique process in the making of dark tea. The wet-piling process itself is the fermentation process, where compressed dark tea leaves are sprinkled with water under controlled Humidity and temperature conditions. This promotes the action of enzymes within the tea leaves and the activity of microorganisms, facilitating the transformation of the tea.
The wet-piling process itself is the fermentation process.
Compressed dark tea leaves are sprinkled with water under controlled humidity and temperature conditions. This promotes the action of enzymes within the tea leaves and the activity of microorganisms, facilitating the transformation of the tea. When the core temperature reaches 70 degrees Celsius, the pile is turned to ensure even temperature distribution, a process repeated multiple times.
When all conditions are optimal, the Metabolism of the microorganisms, along with the extracellular enzymes they secrete, can break down many substances in the tea, such as polyphenols, polysaccharides, pectic substances, terpenoids, and proteins. This forms the distinctive aroma and taste of dark tea and activates its excellent Health benefits.
In addition to wet-piling fermentation, dark tea undergoes a unique second fermentation, often referred to as post-fermentation, which is the real ace up its sleeve.
Experiments have shown that yeast is rich in various vitamins, minerals, and enzymes, aiding in the absorption of other nutrients by the human body. Therefore, the value of this secondary fermentation is evident.
The final step in the production of dark tea is compressing it into brick or cake form before embarking on a long journey. During this journey, the tea is typically stored in a well-ventilated environment with controlled humidity and temperature. After several years of natural fermentation, it is ready for consumption. This process is known as secondary fermentation or post-fermentation.
Which Teas Undergo Post-fermentation?
Teas that undergo post-fermentation include Liu Bao tea from Guangxi, Hunan dark tea (such as Fu tea, Qianliang tea, dark brick tea, and the three tips), Qingzhuan tea from Hubei, Sichuan border tea, An tea from Anhui (also known as Gu Yi black tea), Yunnan dark tea (Pu'er tea), Shaanxi dark tea (Fu tea), and Kangzhuang Jinyin.