The withering of tea leaves is the first step in processing black tea. The loss of water in fresh leaves makes it easier for the subsequent rolling and fermenting.
During this stage, the cell sap become more concentrated and cell membrane permeability increases.
In tea withering, green tea leaves are spread over a wire-netted platform and trough. A fan driven by induction motor pushes air from below the platform to dry the tea leaves. During this withering process water vaporizes and the rate of water evaporation is related to the humidity and temperature.
Withering optimization can take anywhere from 6 hours under artificial air and temperature conditions up to 18 hours under natural conditions.
Withering will increases the amino acids for aroma formation, caffeine for cup character, and organic acids for flavor.
Chemical withering is the key process for formation of white tea color, essential to activate the enzyme polyphenol oxidase and peroxidase for color development of white tea.
Tea withering process
