The Green Tea Steaming Process

Every kind of tea leaf goes through a steaming process, and in the case of green tea leaves, it happens right after picking. Green tea leaves, when picked, are sent right away to a crude tea factory, where the process goes through high heat. The steaming process is crucial, as it is responsible for stopping oxidation in tea leaves. However, if the process is skipped, then the enzymes present in tea leaves change the original components by oxidizing polyphenols, resulting in the oxidation of catechin.

Catechins are the main and vital nutrients in green tea leaves and are responsible for many health benefits. They also give the tea an astringent taste. It works as an antioxidant agent and frees your body from any harmful radicals. Therefore, it is essential to drink green tea, which has gone through each processing step. The steaming process gives your tea a proper taste and keeps the catechins in their original form so you can get their health benefits.

The steaming process was made important and frequently used to eliminate the smell of leaves, enhance aroma, inactivate enzymes, and make the tea leaves softer, making them easier to break down in later processing.

In Japan, the steaming process was introduced long ago, but in recent years, it has gained popularity due to an increase in massive-scale exports. Kobo Daishi, a Japanese monk, learned this method during his visit to China in 804 A.D., and on his return, he taught the technique to other tea vendors. Now every green tea sold in Japan and exported goes through the steaming process.

Nowadays, streaming is done through a tea steaming machine in a properly made factory. The device is made up of a string shaft and a net drum, and both of these parts are covered with steaming drums. When leaves go through this machine, oxidizing enzymes present in fresh leaves are killed due to steam heat. Steamed leaves get a new, fresh green color and contain 75% water. Then it immediately goes through other steps, such as rolling and drying.

The steaming process's length varies in green teas, as the time determines the flavor, aroma, and color of a tea. Each green tea has a specific timed steaming process that varies depending on the growing condition of the tea, the region of cultivation, the elevation, etc. The timing determines most of the results of brewing tea and should be taken seriously for each type of green tea. In the following table, you will see how steaming time changes the fragrance, taste, and color of a tea.

Green Tea steaming time and characteristics

Method	Light Steaming	Normal Steaming	Deep Steaming	Special Streaming	Extra Deep Steaming
Steaming Time	20-30 sec Short time	30-40 sec Short time	40-60 sec Short time	90-120 sec Long time	140-160 sec Two-step steaming
Taste	Clear (astringency)	Slightly rich (astringency)	Rich (astringency)	Deep rich (smoothness)	Strong Low astringency
Fragnance	Strong	Fresh	Fresh	Weak	Light
Leaf Shape	Long, narrow and uniform	Long, narrow and uniform	Long, narrow and uniform	Broken and fine	Coarse
Tea Color	Clear light-green	Clear light-green	Clear light-green	Darkish green	Deep green