From casual conversations at parties to tea-tasting workshops, this is among the top of the frequently asked questions to me : what is the difference between black tea and green tea. And every time I answer it, it has a magical effect – as if I have cast a spell! People flock around, eager and excited, attentive and amazed as I unravel the mystery of this mystical beverage we all know as tea.

Join me as I take you on a humble tea leaf’s chrysalis journey that transforms it into a strong black tea or delicate green tea in a matter of just 24 hours!

Both black and green tea come from the same plant

Both black and green tea come from the same plant – Camellia Sinensis, the scientific name of all tea bushes across the world. After they are harvested (actually, plucked), they go through different processing stages, one of which is Oxidation.

It is Oxidation that is responsible for the tea to transform into black tea or green tea.

What does Oxidation actually do?

Remember the chemistry class at school? Oxidation happens with when food reacts with oxygen in the air. It is due to oxidation that a peeled banana or a cut apple starts turning black. Exactly the same thing happens with the tea leaves – when tea leaves are allowed to oxidise in controlled conditions, the bio-chemical compounds in the tea leaves are exposed to oxygen in the air, a complex reaction takes place making the tea leaves change their appearance from green to black (actually, it is a dark shade of copper). After the leaves attain an optimal level of oxidation, they are passed through a long, flat conveyor at a high temperature. This is called Firing or Drying, and is similar to baking (imagine loaves being baked inside an oven). Firing stops the oxidisation process, reducing moisture to around 3-4%. When the tea emerges after firing, it become the familiar black tea we know.

So, it is oxidation what makes a tea black.

Green Tea

When green tea is made, the oxidation process is completely bypassed. In other words, green tea is what you get when the tea leaves are not allowed to react with the oxygen in air, and hence, retain their bright green colour.

The tea leaves, after being plucked, undergo a quick heat treatment to destroy the tea enzyme. In Japan, this is done by steaming the tea leaves, while in China, tea leaves are pan fried.

After heat treatment, the tea leaves are semi-dried and rolled – either by hand or in rollers. They then undergo firing to remove excess moisture, and are then graded, sorted and packed.

The only difference between black tea and green tea, therefore, is the oxidation process.

To recap :

1. Both black tea and green tea come from the same plant – Camellia Sinensis
2. It is the oxidation process that turns the same tea leaf into black tea or green tea