During the processing of black tea, the chemical reaction occurred on tea polyphenols oxidation. Fresh leaves changed a lot in chemical composition, the tea polyphenols decreased by more than 90% which resulting in new components such as theaflavins and thearubigins. And aroma changed from fresh leaf accordingly, has the black tea characteristics; red color of tea soup and tea leaf, sweetness of the taste.
There are many types of black tea world wide, expect China, India, East Africa, Indonesia and Sri Lanka also crop grow black tea.
Black tea contains various nutrients such as Carotene, Vitamin A, Calcium, Phosphorus, Magnesium, Potassium, Caffeine,Leucine, Lysine, Glutamic acid, Alanine, Aspartic acid and etc.