Case Studies

Reading the Future of Tea Leaves

Challenge

Tea is the second most commonly consumed beverage on earth, behind water, due in part to the purported health benefits associated with the polyphenolic compounds present. Pu-erh tea is made from wide-leaved Camellia sinensis (tea) in subtropical Yunnan Province, China. Like up-market wines, pu-erh tea is highly collectable. Its leaves are kept intact, allowing character to develop with microbial action over time. This is unlike other teas that become stale. A client and purveyor of fine, collectable tea requested evaluation of widespread claims that fermented pu-erh is healthier and richer in antioxidants than young ‘raw’ unfermented pu-erh.
 

Solution

Polyphenols are the largest class of compounds identified in tea. The functional quality of pu-erh is largely dependent on the concentration and composition of polyphenols present, which can vary with respect to area of production, harvest season and processing. We reduced these variables by sourcing raw and fermented pu-erh teas from individual tea farmers in Yunnan. Assays were used to measure the total polyphenolic/antioxidant content in the tea broths and determine the effects of microbial fermentation on the composition of chemicals linked to purported health benefits.
 

Outcome

We found that tea broth from raw pu-erh provided more than twice the concentration of polyphenolic antioxidants than did broth from fermented pu-erh, contradicting claims that fermented pu-erh is healthier and richer in antioxidants than young ‘raw’ unfermented pu-erh. These data were used by our client to support tea comparisons for marketing purposes.