They are three basic types of tea. They differ mainly in the degree of fermentation. Green tea undergoes little or no fermentation and black tea is produced by full fermentation, semi-fermented tea – oolong tea is the product of partial fermentation.
The fermentation process of tea leaves begins with drying, which is followed by twisting and then rolling to separate the leaf cells and release the oils (oil provides the taste). This step initiates fermentation.
Fermentation is caused by the oxidation of enzymes. The dark color of red tea is caused by full fomentation process, where as oolong is half fermented.
During fermentation, the tannin in tea is partly oxidized and the leaf changes color and turns bright coppery red.
Then the leaves are spread out of a cool, damp place, where they absorb oxygen and undergo further fermentation. The final step is drying by hot air to stop fermentation process and give the tea a uniform color, taste and aroma.
The period of fermentation generally extends for 3 to 4 hours. As a rule, the shorter the fermentation the more pungent the liquor; the longer the fermentation the softer the liquor and deeper the color.
Fermentation of tea
