In the manufacturing process, it’s the oxidation that determines whether tea is white, green, yellow, red (in Europe and Russia it is accustomed to call this tea ‘black’.), oolong (blue-green) or black (pu-erh). This classification goes back to the Ming Dynasty years in China and it is based on the color of the wet processed leaves after having been infused.

The oxidation (or fermentation) happens naturally when the leaf dies (the same process that makes leaves turn in fall), and it is the grower who controls, accelerates, or halts the process depending on the desired tea color.

White, green and yellow teas are in the non-oxidized category; oolong (blue-green), red and black are in the fully oxidized category. Although in the same category, the processing of white and yellow teas is slightly different from green tea. Harvested tea leaves have to be transported quickly to the processing plant so that their oxidation process can be controlled. If it is a green or yellow tea is eng produced, oxidation is prevented by high-heat fixation which destroys the enzymes that are responsible for the oxidation. For blue-green or red teas, varying levels of oxidation are used. Black tea is produced thorough organic fermentation.