Ripe Pu-erh Tea or Shu Cha (熟茶) tea is a sub-type of Pu-erh tea that has undergone a “wet piling” process. Wet Piling aka “wo dui” was originally applied to Pu-erh in the 1970’s as a way to fast age raw pu-erh (sheng cha), making it more palatable and smooth like a fully aged raw pu-erh.
“Ripened” Shu Cha (熟茶) tea is pressed maocha that has been specially processed to imitate aged “raw” Sheng Cha tea. Although it is also known in English as cooked pu’er, the process does not actually employ cooking to imitate the aging process. The term may be due to inaccurate translation, as shóu (熟) means both “fully cooked” and “fully ripened”.
The process used to convert máochá into ripened pu’er manipulates conditions to approximate the result of the aging process by prolonged bacterial and fungal fermentation in a warm humid environment under controlled conditions, a technique called Wò Duī (渥堆, “wet piling” in English), which involves piling, dampening, and turning the tea leaves in a manner much akin to composting.
The piling, wetting, and mixing of the piled máochá ensures even fermentation. The bacterial and fungal cultures found in the fermenting piles were found to vary widely from factory to factory throughout Yunnan, consisting of multiple strains of Aspergillus spp., Penicillium spp., yeasts, and a wide range of other microflora. Control over the multiple variables in the ripening process, particularly humidity and the growth of Aspergillus spp., is key in producing ripened pu’er of high quality. Poor control in fermentation/oxidation process can result in bad ripened pu’er, characterized by badly decomposed leaves and an aroma and texture reminiscent of compost. The ripening process typically takes between 45 and 60 days on average.
The Wò Duī process was first developed in 1973 by Menghai Tea Factory and Kunming Tea Factory to imitate the flavor and color of aged raw pu’er, and was an adaptation of wet storage techniques used by merchants to artificially simulate ageing of their teas. Mass production of ripened pu’er began in 1975. It can be consumed without further aging, or it can be stored further to “air out” some of the less savory flavors and aromas acquired during fermentation. The tea is sold both in flattened and loose form. Some tea collectors believe “ripened” Shu Cha should not be aged for more than a decade.
Wet pile fermented pu’er has higher levels of caffeine and much higher levels of gallic acid compared with traditionally aged raw pu’er. Additionally, traditionally aged pu’er has higher levels of the antioxidant and carcinogen-trapping epigallocatechin gallate as well as (+)-catechin, (–)-epicatechin, (–)-epigallocatechin, gallocatechin gallate, and epicatechin gallate than wet pile fermented pu’er. Finally, wet pile fermented puer has much lower total levels for all catechins than traditional pu’er and other teas except for black tea which also has low total catechins.