Tea (Camellia sinensis) is the second most consumed beverage in the world, after water. Teas are divided into 3 categories based on their fermentation level: green (nonfermented), oolong (semi- fermented), and black (fully fermented). The purpose of tea fermentation is to enhance the flavor, which is the most important element for tea evaluation. Oolong tea is mostly produced and consumed in Taiwan and southern China; however, in recent years, consumption of oolong tea has become more popular in the world, especially in China and Japan .
Ref: Ershad Sheibani, Susan E. Duncan, David D. Kuhn, Andrea M. Dietrich, and Sean F. O’Keefe - SDE and SPME Analysis of Flavor Compounds in Jin Xuan Oolong Tea . Journal of Food Science . Vol. 81, Nr. 2, 2016