Black and Green Tea - How Do they differ

Both black tea and green tea come from the same plant “Camellia Sinensis”. However, the manufacturing process that the leaves undergo to make the final tea is different.

In black tea processing the plucked green leaves are withered for several hours to reduce the moisture content and then rolled by mechanical rollers to break them in to parts. This process starts a series of chemical reactions that are catalyzed by the enzymes in the leaf. These chemical reactions are allowed to take place in the next stage of oxidization or fermentation. The major reaction is the conversion of “catechins” (flavonols), the major componenet in the leaf, to what is known as “theaflavins” and “thearubigins” etc. which are responsible for taste and character of black tea.

In green tea manufacturing, the plucked green leaves are subject to heat by steaming or putting in a heated pan to reduce the moisture. The oxidization or fermentation stage is avoided in the manufacture of green tea, which inactivate the enzymes. Thus, the chemical composition of green tea is similar to that of fresh tender tea leaves. In “Oolong tea”, fermentation is allowed for a short period.

Black tea accounts for 74% of world tea production, green tea 24% and Oolong tea for the balance 2%.

Black and green teas both contain similar amounts of “flavonoids” but they differ in their chemical structure. Green teas contain more of the simple flavonoids called “catechins” while the fermentation (oxidization) process that the leaves undergo to make black tea converts these simple flavonoids to the more complex varities called “theaflavins” and “thearubigins”.

The polypenols, particularly those called “flavonoids”, are strong antioxidants. Flavonoids include catechins, theaflavins and therubigins, and are mainly responsible for the health – giving beneficial effects of tea.

A comparison of the content of the different flavonoids in black and green tea brew is given below:

Until recently, green tea was thought to be the most effective antioxidant-containing tea. However, recent “in vitro studies” have shown that theaflavins and therubigins produced during the manufacturing process of black tea are equally effective antioxidants. The health benefits gained from drinking black and green tea are comparable, both helping towards promoting health and well-being. The decision about which kind of tea to drink is simply a matter of taste.