Pu-erh tea is renowned as a 'drinkable antique,' with its unique quality of improving with age widely recognized. The quality of Pu-erh tea is closely related to its main chemical components, such as tea polyphenols, amino acids, and soluble sugars. The storage process of Pu-erh tea is essentially a slow oxidation of these chemical substances.

After a certain period of storage, the tea's color changes from the original yellow-green or orange-yellow of raw Pu-erh to the deep red and bright hue of ripe Pu-erh. The flavor becomes smoother and more mellow. As tea polyphenols oxidize, esterified catechins decrease, and soluble sugars increase, the astringency and bitterness diminish, sweetness intensifies, and a distinctive aged aroma emerges.

Generally, the transformation of Pu-erh tea can be divided into the following seven stages:

New tea stage (1-3 years): The tea soup is yellow-green or yellow, with a strong fresh green aroma and sweet notes. The taste is slightly bitter and astringent. The dry tea is dark green, and the brewed leaves are yellow-green. Experienced tea drinkers can identify the tea's origin and appreciate its robust mountain character.

Early transformation stage (3-10 years): The tea soup turns yellow-red, with a reduced fresh green aroma and a more pronounced honeyed sweetness. The bitterness and astringency lessen. The dry tea is dark green, and the brewed leaves are yellow.

Mid-transformation stage (10-20 years): The tea soup becomes red, with no fresh green aroma but a blend of honeyed sweetness and aged fragrance. The bitterness and astringency are almost gone, and the tea soup thickens, resembling rice porridge. The dry tea is black and glossy, and the brewed leaves are yellow with brown hints.

Late transformation stage (20-40 years): The tea soup is deep red, with a strong camphor aroma. There is no bitterness, and the tea dissolves smoothly in the mouth. The soup is thick like rice porridge. The dry tea is dark brown and shiny, and the brewed leaves are light brown. It becomes harder to identify the tea's origin, and the dissolving sensation is more pronounced.

Aged tea stage (40-60 years): The tea soup is wine-red, with a camphor aroma mixed with medicinal notes. There is no bitterness, and the tea dissolves smoothly. The soup is as thick as rice porridge. The dry tea is dark brown, and the brewed leaves are reddish-brown. The dissolving sensation brings great pleasure.

Vintage tea stage (60-100 years): The tea soup is bright wine-red, with a strong medicinal aroma. There is no bitterness, and the tea dissolves instantly. The soup is as thick as rice porridge. The dry tea is dark brown, and the brewed leaves are brown. The tea dissolves immediately, with a lingering aged fragrance and a sense of time's passage.

Ancient tea stage (over 100 years): The tea soup is bright wine-red and crystal clear, with a strong medicinal aroma. It dissolves instantly, and the soup is as thick as rice porridge. The dry tea is dark brown, and the brewed leaves are brown. The tea exudes an ancient charm and leaves a lasting fragrance on the palate.