Eh, are they all the same? A simple explanation of the differences between green tea, black tea, and oolong tea

Introduction

Green tea, oolong tea, black tea, etc. are made using different methods and look and taste completely different, but did you know that they are all actually made from the same plant and made from the same leaves?

Tea is a general term for drinks made from the tea plant.

All types of tea, including green tea, black tea, and oolong tea, are actually made from the same plant, the Camellia genus of the Theaceae family, the tea plant.

The scientific name of the tea plant is Camellia sinensis. It is a member of the same family as camellias, so if you compare tea leaves with camellia leaves, they look very similar. It blooms with cute white flowers from autumn to winter.

The difference between each tea is the degree of fermentation

Tea is loved all over the world. Even though they all have the same raw material, tea, why do they have such vastly different flavors, tastes, and colors?

This is due to the difference in the degree of oxidation and fermentation of the picked tea.
Depending on the degree to which the tea leaves are fermented during the manufacturing process, they can be broadly classified into the following three types:

1. Unfermented tea (green tea)

This tea is barely fermented.

Green tea is made by steaming and drying the tea leaves immediately after picking to prevent fermentation. This allows the tea leaves to retain their natural green color, aroma, and astringency, and is rich in nutrients such as catechins and vitamin C.

Typical types of green tea include sencha, gyokuro, and hojicha, which are familiar to Japanese people.

2. Fermented tea (black tea)

It is made by allowing fermentation to proceed sufficiently.

After the tea leaves are picked, they are withered to remove moisture, then rolled and fermented. As the fermentation process progresses, the tea leaves turn reddish brown and develop a distinctive, mellow aroma.

The main producing areas are India and Sri Lanka.

3. Semi-fermented tea (green tea)

This is tea in which fermentation is stopped before the tea leaves are completely fermented. It is somewhere between green tea and black tea. The taste and aroma vary greatly depending on the degree of fermentation. A typical type is oolong tea.

What is tea fermentation?

The term "fermentation" that we often hear refers to the processing of original foods through the action of microorganisms such as lactic acid bacteria and yeast, as in pickles and yogurt, but the fermentation of tea refers mainly to oxidation by the enzymes contained in the tea leaves.

Tea leaves contain an enzyme called polyphenol oxidase, and the tannins contained in this enzyme oxidize rapidly when they come into contact with oxygen in the air.

In other words, if no intervention is done, fermentation will continue, and not only will the color appear, but the flavor and taste will also change.

The activity of enzymes stops when heated, so by adding processes such as brewing or steaming the picked tea leaves and controlling the degree of fermentation, a variety of teas are produced, including green tea, oolong tea, and black tea.

Different colors of tea

When you cut an apple and expose it to air, it gradually turns brown. This is because apples contain the same polyphenol oxidase enzymes as tea leaves. The same changes occur in tea leaves, which also affect the color (blue) of the tea when brewed.

If tea leaves are left alone after being picked, the enzymes contained in the leaves will cause them to oxidize and discolor.

Green tea and other unfermented teas are heated as soon as possible after the leaves are picked to stop the activity of enzymes, which is why green tea leaves retain their green color.

Black tea turns reddish brown because the enzymes in the tea leaves do not stop working. The catechin component oxidizes to produce the reddish brown pigment. Oolong tea is produced in a way that is intermediate between the two, so the color is a medium shade such as bright orange.

The two most common types of tea

There are over several hundred varieties of tea in the world, but the two most common are the Chinese variety and the Assam variety.

The Chinese species is a small shrub with leaves only 3-5cm long, but is relatively cold-resistant and has a crisp flavor. It is mainly used to make green tea and oolong tea.

The other variety, Assam, is a tall tree with large leaves measuring 10-18cm in length, but has a rich, mellow flavor. It is primarily used to make black tea.

Besides their appearance and taste, there are also some differences in the ingredients they contain. The Chinese variety, which is cultivated in China and Japan, contains a lot of amino acids that give it umami flavor, but has a low amount of catechin, the bitter and astringent component, and is used in green tea and oolong tea.

On the other hand, the Assam variety found in India and other countries is used in black tea because it has a high content of catechins and low levels of amino acids.