Aging is a critical step for sheng (raw) Tea, not just for storage but also for transforming it towards being fragrant, mellow, sweet, smooth, and lubricating. Beyond aging to achieve higher prices, what else does aging bring to raw Pu'er tea?

Sensory Changes

During storage, due to factors such as moisture, temperature, and sunlight, changes occur in the color, taste, and aroma of raw Pu'er. The color of the infusion shifts from greenish-yellow to reddish-yellow, the aroma transforms from fresh to aged, and any sun-dried scent diminishes or disappears.

Changes in Aroma

Pu'er tea has earned the reputation as a “drinkable antique” due to its unique quality of becoming more fragrant with age, which is also a significant factor in determining the price of aged Pu'er in the market. Under suitable storage conditions, Pu'er tea can develop various aromas during aging, including roasted, phenolic, aged, and woody scents.

Changes in Soluble Extract Content

Soluble extracts include catechins, soluble sugars, amino acids, Caffeine, and water-soluble Pectin, among others. The level of water-soluble extracts reflects the amount of soluble substances in Pu'er tea, indicating the thickness of the infusion and the intensity of the flavor. However, there is no definitive conclusion regarding the relationship between aging time and the amount of soluble extracts.

Changes in Infusion Color

Tea contains large amounts of polyphenols, a collective term for several compounds, with catechins being the main component. Catechins are closely related to the color, taste, and aroma of the tea. Catechins are colorless, have a bitter and astringent taste, and are highly stimulating. During storage, they tend to undergo auto-oxidation, first dehydrogenating into quinones and then further polymerizing into brown pigments. These combined changes in pigments lead to a gradual darkening of the infusion color.

Changes in Caffeine Content

Caffeine, one of the characteristic components of tea leaves, is the most abundant alkaloid found in tea. Current research consistently shows that caffeine decreases over time during the storage of tea.