Let us for the moment focus on tea from the tea plant. Simply processing the leaves differently yields the different major tea categories.
On one end of the spectrum is white tea which contains wilted and unoxidized leaves. On the other end of the spectrum is black tea which contains wilted and fully oxidized leaves which are most of the time crushed. On the other hand, green tea is made of unwilted and unoxidized leaves.
After picking the leaves, they quickly start wilting and an enzyme in the leaves starts the process of oxidation. The oxidation makes the leaves darker and releases the tannins. The oxidation can be stopped by heat. Heat also serves to preserve the tea and protect it from mold.
Tannins are polyphenolic biomolecules that bind to … who cares? Unless you are a chemist, I would say you enjoy brewing and drinking tea. A few interesting facts about tannins: They are contained in many plants and play a role in the plant’s protection against pesticides. In medieval times the term tannin referred to the use of bark, mostly from oak, to tan animal hides into leather.
The process of producing teas is of course much more complicated than drying plant leaves. There are even some teas that require aging. These aging processes are delicate to control and require time. Similar to wine: The exclusivity of such aged teas is reflected in their price. Maybe I will blog about such teas another time.