Green pu-erh tea is sometimes called "raw" pu-erh. The Chinese name for this pu-erh is "sheng pu-erh" and it can be divided into two types: Young green pu-erh tea which has not completely fermented; and green pu-erh which has undergone a complete fermentation through dry storage.
Young pu-erh tea is quite astringent and needs to be brewed properly to overcome its weakness. It benefits greatly from aging. The longer the pu-erh is aged the better it becomes. The tea is stored in a dry environment for several years, during which the pu-erh is undergoing a fermentation process due to microbes which are present in the tea leaves.
The aging process of green pu-erh tea can be hastened artificially by storing it in a humid environment. This process is called "aspergillus post-fermentation" and is used on cheaper grades of pu-erh tea. This type of pu-erh is not recommended because if it is not processed correctly it can contain harmful bacteria.
During the final stage of processing the tea leaves for green pu-erh tea can be steamed and pressed into shapes. Green pu-erh tea is also available in loose-leaf form, for which there are 10 grades.
Pressed Pu-erh Tea
Steaming and compressing the tea leaves gives the pu-erh tea a distinctive quality which is not found in loose-leaf pu-erh. The leaves can be pressed into a number of shapes including bricks, balls, and bowls.
The loose leaves are first weighed and placed in a linen bag. This bag is placed in a mold and heated with steam. The tea is then removed from the mold and the bag and placed on a rack where it rests for about 6 or 7 hours. This preliminary storage room is heated with steam to maintain a high humidity.
After this initial settling, the pressed pu-erh is transferred to a dry storage area. The storage area must have adequate air circulation and the humidity level must not be too high. The climate of the Pu-erh area in Yunnan province provides ideal storage conditions without the need of artificial heating or de-humidifying equipment.
Due to the active microbial activity in pu-erh tea, green pu-erh continues to evolve the longer it is stored. This causes green pu-erh tea to rise in value as it ages, making pu-erh bricks valuable collectibles that some people treat as investments.