Table 1: Unitary operations involved in tea processing.

Unitary Process	Description
Fixation	Carried out by steaming, pan-fired, and sunning. The aim is to deactivate the endogenous enzymes presented in the fresh tea leaves
Withering	Natural and spontaneous process that allows the reduction of the moisture content of tea leaves. The aim of the withering is to improve the flavor in green, oolong, and black tea
Rolling	Performed to obtain the different kinds of shape of tea leaves
Fermentation	It is so-called the enzymatic oxidation catalyzed by PPO in order to oxidize polyphenols into tannins and complex quinones
Drying	Unitary operation performed in order to stop the oxidation progress and to reach a moisture level of 3-4% (wet basis) to facilitate handling and transportation