top of page

The power of the scent of roasted tea


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

But what features does the aroma have, exactly?




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 type of amino acid, a derivative of glutamic acid, and is abundant in tea leaves.  Roasted tea includes only about 1% as much theanine as green tea does, and while this may seem insufficient, the amount is actually more than enough to produce the relaxation effect.



So it has been discovered that the intake of roasted tea is causing as much relaxation effect as that of green tea.  Moreover, even without drinking 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


実験: 杏林大学 医学部 精神神経科 古賀良彦教授

data from prof. Yoshihiko Koga, medical department(neuropsychiatry) of Kyorin University

2. The 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 "sealed" inside the leaves.  When the leaves are heated gradually, the aromatic ingredients can flow outside the leaves.  Furthermore, 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 the intensity of each ingredient between green tea and roasted tea.      

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 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


Roasted tea receives a general impression of lower quality because it is made of thicker or staler tea leaves that have less commercial value or lower grades.  But it is very interesting that 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.




A NHK TV popular-science program "This is super Japanese tea; economy and tasteful bliss 1200 times as much "


Home page of Industrial Research Institute of Ishikawa




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」



bottom of page