When discussing the flavors of ripe Pu'er Tea, one cannot avoid mentioning the “Menghai Flavor.” According to Mr. Chen Jie, “The term ‘Menghai Flavor' originated at the end of the 1990s and refers to a distinctive ‘taste sensation' associated with Pu'er tea (especially ripe tea) produced by Yunnan Menghai Tea Factory. This flavor has become an important identifier distinguishing Menghai Tea Factory from other manufacturers.”
Nowadays, many tea factories are conducting fermentation in Menghai and have produced high-quality ripe Pu'er teas with similar flavors, which have been enjoyed by more consumers. Today, let's delve into the origin of the Menghai Flavor and explore how Daye No.7 Research Institute successfully applies modern technology to uncover and practice the causes of the Menghai Flavor.
The microorganisms involved in the fermentation process generate heat through activities such as oxidation, respiration, catalysis, decomposition, and transformation, which helps to increase the temperature of the fermentation pile and promote the fermentation process. Higher temperatures kill harmful bacteria and benefit the growth, reproduction, and physiological Metabolism of beneficial bacteria. But which specific strains are involved?
Daye Group has been researching this topic for quite some time. In 2010, they initiated a national natural science fund project titled “Study on the Mechanism of Piling Fermentation in Pu'er Tea,” established Yunnan's first postdoctoral workstation, attracted talent, formed a professional team, and collaborated with experts from multiple research institutions and machinery companies to conduct research and application studies. They were among the earliest enterprises in the tea industry to focus on microbial research.
Today, let's visit Daye No.7 Research Institute—Yunnan Daye Microbial Technology Co., Ltd. Under the leadership of Gao Linrui, we will learn about the third-generation intelligent fermentation technology—the “Microbial Formula” tea-making method.
50-Year-Old Daye Fermentation Pool: The Mystery of the Menghai Flavor
The quality of ripe tea is closely related to its formula, raw materials, and piling process, but another crucial element is the microbial environment.
To understand the microbial environment, we must first recognize the microbial community, which consists of eight major families: bacteria, viruses, fungi, actinomycetes, rickettsiae, mycoplasmas, and spirochetes. Under each major family, there are countless smaller families. These tiny, invisible creatures have different attitudes towards humans. Some are hostile and cause illnesses, acting as cold-blooded killers, while others help people fight diseases, like antibiotics such as penicillin. In ripe tea, beneficial microorganisms make the tea more enjoyable and beneficial to human health, whereas harmful ones can damage health and produce unpleasant flavors.
From 2010 to 2013, Gao Linrui conducted research at the technical center of Menghai Tea Factory and found that the old fermentation pools of Menghai Tea Factory follow a certain regular pattern of microbial activity, which pointed him towards the future industrial development direction of Pu'er tea in the field of microbial science. “We knew very early on that the relationship between Pu'er tea and microorganisms is very close, especially during artificial fermentation, where microorganisms play the most critical role,” he said.
The unique microbial environment of Menghai has nurtured excellent fermenting bacterial strains, which are irreplaceable and cannot be replicated. It takes decades, ranging from ten to several decades, to form this environment, involving the aggregation effect of biological populations. This cannot be achieved merely by investing money, improving tea-making techniques, or enhancing raw material quality.
The formation of a stable fermentation environment is a long-term process. A single species of microorganism gathers to share a common food source and habitat, and to dominate the ecosystem, it must compete with others. Similarly, the formation of dominant fermentation bacteria requires the microbial environment to produce antagonistic effects. This involves prolonged fermentation, where fermentation bacteria grow and reproduce using the pile as a substrate, occupying the entire environment and squeezing out other microorganisms. This process is repeated over time, requiring a long period of struggle. Menghai Tea Factory has been continuously fermenting since 1973, and among all factors, microorganisms are the most crucial. After decades of accumulation, the Daye fermentation pool has now formed a relatively stable microbial flora structure, which is key to the formation of the “Menghai Flavor” in Daye tea.
Ten Years of Sharpening a Sword—Microbial Tea-Making Method
With a significant reduction in the cost of gene sequencing, microbial research has gained opportunities for large-scale studies. By 2016, Gao Linrui and his team had finally clarified the growth and decline patterns of microorganisms during the fermentation process of Pu'er tea—the changes in quality after microorganisms act on raw tea and their relationships with each other. For complex matters, simplifying them makes success more likely. However, when dealing with something as complex as microbial research, one cannot simplify it; instead, it requires substantial scientific research and continuous efforts. Gao Linrui humorously described this period as a long and lonely “cold bench.”
Gao Linrui believes that “the entire process of microbial research should be systematic, comprehensive, and continuous. Otherwise, in the vast and mysterious world of microorganisms, the discoveries made in these intermittent studies are just glimpses of a larger picture. Microbial research is a complex task. If continuous research is not conducted, it is easy to get a fragmented understanding of Pu'er tea, which is a macroscopic and systematic project. Furthermore, we discovered that microorganisms have strong regional characteristics, and samples must be fresh. If I were to send samples taken from the old fermentation pools of Menghai Tea Factory to Kunming, they would die before arrival. Sampling must be done on-site.”
Every day, Gao Linrui and his team perform extremely complex and tedious work, continuously sequencing and analyzing the microbial samples. “This is where we put in our effort! Our strain library contains mother strains from Menghai Tea Factory, with thousands of strains making it difficult to distinguish between good and bad ones. After all, there are many microorganisms in the old fermentation pools of Menghai Tea Factory. We need to determine which ones are good and which are not through gene sequencing. We classify them, differentiate between strains, and continuously send them for gene sequencing. We analyze the sequences, make judgments, and validate them. We study them under the microscope every day until we identify the strains that truly produce the distinct ‘Menghai Flavor.' This process was incredibly painful.”
The bacterial mother strains originate from the fermentation pools used by the old Menghai Tea Factory since 1973 for the fermentation of ripe tea. Daye has been dedicated to fermentation, integrating all favorable conditions. Since 2006, Gao Linrui has been conducting ripe tea fermentation at Menghai Tea Factory, with fermentation piles present every day regardless of the season. “This ensures the continuity of samples. The process took six years, during which approximately 20,000 samples were collected. Daily sampling allowed us to compare samples continuously, ensuring consistency. Without sufficient quantity, this would not have been possible. The samples needed to be rich and representative, reflecting the characteristics of the fermentation pile. We finally understood the development patterns of microorganisms in the Daye fermentation pools.”
Regarding the traditional fermentation of ripe tea, which typically conjures up images of piles of tea leaves, no one knows which microorganisms participate. Gao Linrui refers to this traditional fermentation as “natural inoculation.” Traditional fermentation relies heavily on the experience of the fermentation master, and the participating strains come from various aspects of nature. However, after persistent and uninterrupted research, Gao Linrui's team has confirmed that several key common microorganisms are essential to the microecosystem and play a decisive role in the formation of the quality and activity of Pu'er tea. It is time to take control of the microorganisms truly involved in the fermentation of ripe tea and harness their true potential.
To achieve controllable Pu'er tea production processes, equipment innovation is necessary. Daye has developed systems for input and output of materials, stirring, sterilization,