The most important differences between the various groups of tea varieties are the result of fermentation.
Fermentation is loosely understood as a process of oxidation and fermentation of the released cell sap through exposure to oxygen.
The fermentation is caused by enzymes contained within the leaves, which particularly affect the naturally present catechins.
If such fermentation is to be prevented, e.g. in green teas, these enzymes – or to give them their correct name: polyphenol oxidases – are rendered ineffective through the application of heat.
To apply heat, it is possible to use dry heat or steam.
Important processes during fermentation...
- Catechins are partly altered (oxidation) Theaflavins and thearubigins are formed
- Flavouring agents are formed from fatty substances and as a result of the degradation of carotinoids
- Chlorophyll is degraded through the change from green to black
