Thousands of years before the term “microorganism” was even coined, ingenious Chinese people had already begun utilizing microorganisms in food. Our ancestors discovered early on that fermentation could enhance the taste of food and extend its storage life, leading to the creative invention of a series of fermentation techniques and fermented foods: Tea, alcohol, soy sauce, vinegar, steamed buns, yogurt, sweet rice wine, etc., which greatly enriched the daily lives of Chinese people.

Modern science defines fermentation as the process of growing and chemically changing microorganisms (or animal and plant cells) to produce and accumulate specific metabolites. In fermented foods, we tend to view alcoholic beverages like wine and liquor as the pinnacle of traditional fermentation technology but often overlook another peak – Pu'er tea. From being a “border trade commodity” to becoming an “upscale beverage,” Pu'er tea has now become the darling of many. People have discovered its charm of “improving with age,” and it's fermentation that has turned Pu'er tea into a “comeback king.”

Post-fermentation – The Pu'er Tea Development Diary

The fermentation of Pu'er tea is like a well-timed drama, starting with a greenish scent and gradually developing into Orchid, honey, smoke, jujube, camphor, medicinal, and other fragrances. Who knows what other surprises it might bring? Traditionally, tea is valued for its freshness, but Pu'er tea breaks the rules – the older it gets, the more precious it becomes. Fermentation allows Pu'er tea to “improve with age.”

When divided by stage, the fermentation process of Pu'er tea can be categorized into pre-fermentation and post-fermentation. The sun-dried raw tea leaves of Pu'er tea start fermenting while exposed to sunlight. Additionally, during natural air-drying, the high moisture content in the leaves triggers the oxidation of organic substances within them, known as pre-fermentation.

The post-fermentation of Pu'er tea primarily involves various types of microorganisms, such as Aspergillus, yeast fungi spores, and mycelia. These organisms rely on tea leaves as their nutrient base and grow and reproduce under suitable temperature and humidity conditions. When the temperature is above 15 degrees Celsius and the relative humidity is over 60%, the spores germinate, and the mycelium produces spores, undergoing both asexual and sexual reproduction at a rapid pace, sometimes completing a generation cycle in just tens of minutes or hours. Then, using enzymes produced by different microorganisms, they transform organic substances in the tea leaves, such as catechins, sugars, starches, and cellulose, and the heat generated during the proliferation of these fungi changes the color, flavor, and aroma of the tea.

Post-fermentation is the key factor affecting the quality and taste of Pu'er tea, as it is a process of quality remaking. The mycelium undergoes asexual reproduction in summer and autumn and hibernates in winter. During this process, acids are produced, such as citric acid by black Aspergillus. Alcohols, lipids, and especially aromatic esters are also produced. Aromatic esters are the source of the aroma in most fermented foods. As Pu'er tea is stored, seasonal asexual reproduction in summer and autumn and hibernation in winter generate and retain aromatic compounds, which is why Pu'er tea can “improve with age.”

Raw Pu'er tea undergoes natural fermentation. Post-fermentation in the first few years is very slow, but after five or even ten years, the transformation becomes very apparent, particularly in terms of infusion color and mouthfeel. In contrast, although ripe Pu'er tea has undergone artificial fermentation, there is still significant potential for aging through post-fermentation. With meticulous storage and aging, the microorganisms continue to proliferate slowly and oxidize slowly, making the fermentation more thorough and the taste smoother. This post-fermentation process largely depends on the action of filamentous fungi.

Of course, part of the allure of post-fermentation lies in the fact that it is completed by tea keepers (merchants and consumers). Based on their understanding of Pu'er tea, tea keepers control factors like temperature and humidity to “hone” the tea into a higher-quality product. Storing Pu'er tea in regions with different climates, such as Beijing, Shanghai, Tibet, and Kunming, is akin to providing diverse ecological environments for the fungi within the tea. Hot storage accelerates maturation, cold storage enhances aroma, and letting the natural environment, alternating hot and cold, and changing seasons nourish the Pu'er tea makes it “improve with age.” This allows one to witness firsthand the perfect transformation journey of Pu'er tea.

“Enzymes” Hold the Secrets

The reason Pu'er tea can potentially lower blood lipids and alleviate hypertension and hyperlipidemia is due to its rich content of “enzymes.” Enzymes not only promote the post-fermentation of tea but also play a significant role in its Health benefits, making them crucial for the post-fermentation, aging, and consumption of Pu'er tea.

In fact, the biggest secret of Pu'er tea fermentation is “enzymes.” What are enzymes? They are organic colloidal substances produced by living cells within organisms and serve as biological catalysts. All digestive, absorptive, respiratory, locomotive, and reproductive activities in living organisms are enzymatic reactions. They are essential for maintaining normal body functions, digesting food, repairing tissues, and all other life activities.

Activities such as thinking, exercise, sleep, breathing, anger, crying, and hormone secretion are all results of enzyme-centered processes. Enzymes are the foundation upon which cells survive. Many refer to them as “living substances” and “the substance that controls all life activities.”

Because large-leaf tea contains various enzyme elements, enzymes are the most critical component during the fermentation of Pu'er tea. The microorganisms that Pu'er tea relies on for fermentation are the “main force” in enzyme production. One of Pu'er tea's greatest achievements is that all its fermentation processes occur at room temperature, preserving abundant enzymes for us.

Enzymes have a characteristic of being sensitive to high temperatures. Enzymatic fermentation is the most important form of fermentation in the aging process of Pu'er tea and is the essence of its fermentation. During the beneficial fungal fermentation of Pu'er tea, enzymes act as catalysts, accelerating the fermentation process. This enables Pu'er tea to complete fermentation within just a few months.

In summary, Pu'er tea is a natural, high-quality beverage bestowed by nature. Its ability to relieve hangovers, nourish the stomach, and lower the three highs (blood pressure, blood Sugar, and cholesterol) owes much to the role of fermentation. Time gives Pu'er tea a great taste and truly makes it “drinkable antiques.”

Excerpt from Pu'er Magazine

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