At that time, the fermentation process reform experiment was led by the Guangdong Provincial Tea Import and Export Company, while the research on the pile fermentation of Liubao tea fell to the Wuzhou branch of the China Tea Guangxi Provincial Branch (now Wuzhou China Tea).
A book published in 1959 introducing the cold-water pile fermentation process.
At that time, the technical personnel in Wuzhou explored and recorded the process and results of dividing the tea leaves into different grades and adding different proportions of water. The advantages and disadvantages of this process were also listed. The document explicitly states, "Currently, we have implemented this method in our large-scale production, and the finished products supplied to the Guangdong Tea Export Company have received positive feedback." This confirms that the cold-water pile fermentation process for Liubao tea by the Wuzhou branch of the China Tea Guangxi Provincial Branch (now Wuzhou China Tea) had been applied to mass production at least as early as 1958.
In the fermentation workshop of Wuzhou Zhongcha, the cold water pile fermentation tanks that had been in use for decades have now been replaced with clean and hygienic stainless steel tanks.
Most importantly, the improved quality and taste of Liubao tea were recognized by merchants. The special export mission of the Wuzhou Tea Import and Export Company (now Wuzhou China Tea) at that time meant that, until the abolition of the foreign trade tea export license management in 2005, the Liubao tea flavor recognized in Southeast Asia and Hong Kong and Macau was based on Liubao tea produced using the cold-water pile fermentation method.
It is also worth mentioning that in early 1973, the Yunnan Provincial Tea Import and Export Company learned at the Canton Fair that Hong Kong customers needed fermented red-liquor Pu'er tea, and since this type of tea was produced in Guangdong, they decided to learn the process. Around 1975, Yunnan's fermentation process underwent a significant innovation, developing the cold-water pile fermentation process, which led to the creation of ripe Pu'er tea.
It can be said that, whether for Liubao tea or Pu'er tea, the cold-water pile fermentation process was researched and invented under the leadership and organization of the China Tea Company at that time. They were the leaders and pioneers of modern ripe tea processing technology.
Looking back, how important is the pile fermentation process to Liubao tea and ripe Pu'er tea? Numerous papers now show that its principle is to promote the transformation of internal substances through hydrothermal action, enzymatic action, and microbial action, reducing bitterness and astringency, deepening the color of the tea liquor, making the taste mellower, and changing the color of the tea leaves to reddish-brown or dark brown, thus optimizing the quality of the tea.
The Last Secret of Liubao Tea – Cellar Aging
Liubao tea is renowned for its "red, rich, aged, and mellow" characteristics. When brewed, the tea liquor is bright red, the taste is mellow and refreshing, and the aroma is pure. A crucial process in its production is cellar aging. According to records, in ancient times, people in Liubao Township (now Liubao Town) stored tea leaves in mud-brick houses with relatively constant temperatures. Through practice, they discovered that the storage of Liubao tea played a very important role in improving its quality. This was the early form of the cellar aging process for Liubao tea. Furthermore, the book "Tea Manufacturing," published by the Agricultural Publishing House in 1961, explicitly states that Liubao tea "is best when aged, and the older, the better." In short, under certain storage conditions, the post-fermentation of Liubao tea is accelerated due to the participation of microorganisms, making the tea redder, richer, and mellower.
In the current geographical indication standards for Liubao tea, the aging process is described as follows: The tea leaves are placed in a clean, cool, well-ventilated environment free of peculiar odors. After the tea temperature drops to room temperature and the moisture content drops below 18%, it is moved to a clean environment with a relative humidity of 75% to 90%, a temperature of 23℃ to 28℃, and no peculiar odors, or to a cave with similar conditions for aging. Then, it is moved to a clean, cool, dry warehouse free of peculiar odors for further aging. The aging time is no less than 180 days. Therefore, the interpretation of the geographical indication can be that the aging process requires specific storage environments, storage methods, and climatic conditions, but the location is not unique. It can be a tea cellar, a brick and wood warehouse, or a purely dry warehouse, etc. However, different cellar aging environments create different flavors. To obtain the unique and high-quality flavor of Liubao tea, there has always been a practice of "multiple warehouses, multiple storages" and repeated transfers for aging.
The brick and wood structure of Wuzhou Zhongcha's natural dry storage has been in use since the 1960s, with ventilation and moisture protection (glass tiles are used for light transmission).
Going back to the 1950s and 1960s, during the period when modern Liubao tea processing techniques were taking shape, the Wuzhou branch of the China Tea Guangxi Provincial Company (now Wuzhou Zhongcha) further applied the cellar aging process in practice. Technicians discovered that the air-raid shelters left over from the war were excellent places for cellar aging.
In fact, many tea processing techniques originate from accidental discoveries. For example, it is said that the semi-fermentation process of Oolong tea originated from a unique taste obtained through a production error. Therefore, whether a new process can withstand the test of time and taste is crucial.
As is well known, cellar aging is particularly common in the fermentation of alcoholic beverages. Its function is to accelerate the esterification reaction, thereby speeding up the maturation of the alcohol. Moreover, frequently used cellars can form a relatively stable microbial community, which is extremely important for the quality of fermentation. Liu Bao tea that has undergone cellar aging has improved in terms of its bitter and astringent taste, possessing a more mellow flavor.
Exterior view of the natural dry storage structure of Wuzhou Zhongcha brick and wood
However, controlling the quality of tea during the aging process is not something that can be explained solely by textbook knowledge. According to Manager Xie of the Wuzhou China Tea Product Development Department, in addition to data control, the aging process requires experienced masters to conduct regular sensory evaluations. Based on the style of different products, they decide whether to move the tea to a different storage location and control the duration of aging.
Furthermore, Manager Xie also said that the "no less than 180 days" mentioned in the geographical indication is actually a very basic standard. Some Liubao teas that have been aged well for seven or ten years will offer a special aroma and taste, which is the unique charm brought about by the aging and transformation of Liubao tea.
The End
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