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The power of the scent of roasted tea


Houjicha or roasted tea's topmost charm is its excellent scent that relaxes your mind. 

What features does the aroma have actually ?




1. The tea relaxes you even without drinking. 


1. 飲んでいないのに得られるリラックス効果​

Green tea contains an ample amount of theanine, which is a kind of amino acids, a derivative of glutamic acid, and abundant in tea leaves.  Roasted tea includes it only about 1% as much as green tea does, and this makes the relaxation capability of roasted tea look like nearly hopeless.




Theanine amount in 100g of each tea


But it has been discovered the intake of roasted tea is causing as much relaxation effect as that of green tea.  Moreover, even without driking any tea, just the aroma from roasting green tea leaves was verified to yield as much relaxation effect as when drinking it.





A.  Relaxation effect from drinking green tea


A.  緑茶を飲んだ時のリラックス効果

Brain activity level before tea


Expansion of the red part right-below indicates the increase in alpha-wave characteristic to brain relaxation.



Brain activity level after drinking green tea


B.  Relaxation effect from smelling green tea being roasted


B. 緑茶を焙じた時のリラックス効果

Brain activity level before the smell


Expansion of the red part right-below indicates the increase in alpha-wave characteristic to brain relaxation.




Brain activity level while smelling the roast scent


2.  Roasting process frees latent aromatic ingredients.

2. お茶に潜んでいた香りを引き出す「焙じる」という行程

The roasted tea is produced by roasting green tea leaves.  How does roasting change the aromatic ingredients in the leaves ?



Tea leaves contain more than 300 kinds of aromatic ingredients originally, but they are chemically bonded to sugars, and so to say "sealed" inside the leaves.  When the leaves are heated gradually, the aromatic ingredients become capable to free themselves from the sugars so they can flow outside the leaves.  Further, over a certain temperature point, a chemical reaction called amino-carbonyl reaction (Maillard reaction in particular) takes place to bond sugars and amino acids, and to yield aromatic roast scent.    

The graphs on the right identify several characteristic aromatic ingredients that are influential to tea-leaf quality (above), and compare intensity of each ingredient between green tea and roasted tea (below). (The green bars stands for green tea, the yellow roasted.)     

The graphs tell roasted tea exhibits much more outstanding aromatic ingredients both in number and in intensity than green tea does. It is said some ingredients are even intensified to 1200 times  through roasting.






Data from Industrial Research Institute of Ishikawa

データ提供  石川県工業試験場

Intensity spectrum of the aromatic ingredients in green tea緑茶の香気成分の種類と強度

Intensity spectrum of the aromatic ingredients in roasted tea compared to green tea


Roasted tea receives a general impression of lower quality, because it is made of thicker or staler tea leaves that have less commercial values or lower grades.  But it is very interesting the tea profits its strong value from brewing the rich variety of aroma out from the tea leaves so adequately processed as to enhance their aromatic capability maximally, through the roasting as we see it.




参照: ためしてガッテン 2013年6月19日 130619 【これぞスーパー日本茶!格安美味 幸せ1200倍 】


ためしてガッテン これぞスーパー日本茶 格安美味!幸せ1200倍 (2013年06月19日放送)



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