The secret of Sheng (Raw) Pu’er tea processing that allows it to continue aging, transforming, and fermenting over the years lies in several key factors like leaf material, minimal processing, natural microbial fermentation, controlled oxidation over time, storage environment and compression.
Sheng Pu’er is often made from large-leaf Camellia sinensis var. assamica, which has higher levels of polyphenols and pectin that support long-term aging. Older tea trees ("gushu") produce leaves with stronger microbial resilience, aiding in better transformation over decades. Sheng Pu’er is processed using sun-drying instead of high-heat roasting or steaming. This preserves the natural yeasts, bacteria, and fungi that enable post-fermentation over time. Unlike other teas, its enzymes remain active, allowing oxidation and fermentation to continue for decades. The tea contains living microbial cultures (such as Aspergillus, Penicillium, and lactic acid bacteria) that continue to break down tea compounds. As it ages, microbes slowly ferment the tea, developing complex flavors and reducing bitterness. Since Sheng Pu’er is not heavily processed, natural oxidation occurs over years, deepening flavors and reducing astringency. Tea polyphenols and catechins gradually convert into theabrownins and theaflavins, which smooth out bitterness and create depth. Humidity, temperature, and airflow impact how the tea ferments over time. Warmer, humid environments (e.g., Hong Kong, Guangzhou) speed up aging, while cooler, drier climates (e.g., Kunming, Taiwan) slow the process. Proper storage enhances microbial activity, allowing tea to evolve into richer, more complex flavors. Sheng Pu’er is typically compressed into cakes, bricks, or tuocha ("next"). This slows oxidation and microbial activity, allowing even fermentation and preserving flavors over time.