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 |
Get Free Bonus Books
Sign up for free to the Green Tea Club to get advice and exclusive articles about how to choose Japanese Tea, and tips, tricks, and recipes for enjoying Japanese tea.
Unsubscribe anytime. It’s free!
About the author
Kei Nishida
Author, CEO Dream of Japan
Certification: PMP, BS in Computer Science
Education: Western Washington University
Kei Nishida is a passionate Japanese green tea connoisseur, writer, and the founder and CEO of Japanese Green Tea Co., a Dream of Japan Company.
Driven by a deep desire to share the rich flavors of his homeland, he established the only company that sources premium tea grown in nutrient-rich sugarcane soil—earning multiple Global Tea Champion awards.
Expanding his mission of introducing Japan’s finest to the world, Kei pioneered the launch of the first-ever Sumiyaki charcoal-roasted coffee through Japanese Coffee Co. He also brought the artistry of traditional Japanese craftsmanship to the global market by making katana-style handmade knives—crafted by a renowned katana maker—available outside Japan for the first time through Japanese Knife Co.
Kei’s journey continues as he uncovers and shares Japan’s hidden treasures with the world.
Learn more about Kei
