“Why does Pu'er tea become more fragrant with age?”
“What is natural aging of Pu'er tea?”
“Why is Yunnan considered the natural dry warehouse environment for Pu'er tea?”
Some tea enthusiasts who have just started to explore Pu'er tea may still be unfamiliar with concepts like natural aging. In the spirit of serving our fellow tea lovers, we will delve into these questions in detail:
What is Natural Aging of Pu'er Tea?
The natural aging of Pu'er tea, according to a widely accepted definition within the industry, refers to dry warehouse storage and aging.
Some industry insiders believe that only Pu'er raw tea stored in a dry warehouse environment can truly retain the true essence of Pu'er tea, if we consider the tea-drinking experience. However, one drawback of a dry warehouse is that the transformation of Pu'er tea occurs at a slower pace.
The definition of a dry warehouse environment is typically: moderate temperature and Humidity, well-ventilated, clean and hygienic, free from miscellaneous or strange odors. If we were to quantify this more precisely, it would mean a relative humidity between 60% to 70%, an average temperature between 20 to 30 degrees Celsius, clean and hygienic, with moderate ventilation, and free from any strange odors.
Yunnan's Kunming has a relative humidity and temperature that falls within this range, which is why it is considered a natural dry warehouse environment.
Changes in Pu'er Tea During Natural Aging
The natural storage and aging of Pu'er tea essentially involves continuous post-Fermentation during storage. In the process of post-fermentation, the internal components of Pu'er tea undergo a series of biochemical reactions such as oxidation, polymerization, and decomposition under the influence of oxygen, microorganisms, and active enzymes within the tea leaves.
The composition and content of its substances change significantly, leading to changes in the taste and efficacy of the Pu'er tea. The main substance transformations and their component changes are six in total: catechins, flavonoids, amino acids, total sugars, proteins, and aromatic compounds. Let's discuss these changes in more detail:
1. Changes in Catechins
Pu'er tea contains many active substances that are easily oxidized, and catechins are one of the most typical among them. They are closely related to the color, taste, and aroma of the tea. Storage experiments have shown that during storage, catechins in Pu'er raw tea undergo oxidation and polymerization reactions, producing compounds like thearubigins and theabrownins, which alter the color, taste, and efficacy of the tea. As the storage period increases, catechins gradually oxidize and polymerize, transforming into other substances, making the tea liquor redder and the taste sweeter and smoother.
2. Changes in Flavonoids (Catechins)
Flavonoids are the primary component of catechins, accounting for 60% to 80% of the total catechins. They have good health benefits for the human body, helping to eliminate excess free radicals and inhibit aging to some extent. The content and types of catechins change with the storage period and temperature, with the total content showing a downward trend. The longer the storage period and the higher the temperature, the greater the transformation and the faster it occurs.
3. Changes in Amino Acids
Amino acids are not only important substances that affect the taste of the tea but also have a significant impact on the color of the tea liquor. Higher amino acid content generally indicates better tea quality. During storage, the amino acid content in Pu'er tea also changes significantly with the increase in storage time, and the higher the temperature, the greater the decrease in amino acid content. Therefore, storing Pu'er tea in an environment exceeding 35°C leads to a significant decrease in amino acid content, which is not conducive to improving tea quality.
4. Changes in Total Sugars
Total sugars refer to all Sugar substances in Pu'er tea. Changes in total sugars directly affect the color and taste of the tea liquor, being the primary substance responsible for the sweetness of the tea liquor and indirectly influencing the aroma of the tea. As the storage period increases, insoluble sugar substances like cellulose in the tea leaves are broken down by microorganisms and active hydrolytic enzymes into soluble sugar substances like pectin, thus increasing the soluble total sugar content in the tea liquor and improving its taste, making it sweeter and smoother.
5. Changes in Proteins
Proteins are one of the six essential nutrients for the human body. During the storage of Pu'er tea, the protein content changes, and with the increase in storage time, the soluble protein content in the tea liquor gradually increases, thereby enhancing the health benefits of Pu'er tea for the human body.
6. Changes in Aromatic Compounds
Aromatic compounds in tea determine its aroma type and quality. During storage, these aromatic compounds undergo significant changes. Some aromatic compounds decrease or even disappear with the increase in storage time, while others increase. The most typical example is the aromatic compound that determines the aged fragrance of Pu'er tea, which increases with the increase in storage years. Multiple experiments and tests have shown that storing Pu'er tea in environments below 35°C is more beneficial for improving its aroma quality.
The above covers the natural aging of Pu'er tea and the changes that occur during the natural aging process.
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