Dark Tea – Den's Tea website


Collection: Dark Tea

Our Mori-machi Dark Tea is a Pu-erh style tea or a rare fermented green tea made in Japan. It is reminiscent of the well-known fermented tea made in Pu-erh City in China and Mori-machi Dark Tea has a similar taste profile due to the fermenting process.

  • Organic Mori-machi Dark Tea
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Real Black Tea

Unlike the general tea classifications of green, black and oolong that we use in the US and Japan, China has their own unique tea categories which include: Green, Yellow, White, Blue, Red, Black and Flower teas. Dark Tea or Pu-erh tea belongs in the Black Tea category in China and what we call "Black Tea" belongs in Red Tea in China.

Fermentation Processes for Mori-machi Dark Tea

Fermentation Processes for Mori-machi Dark Tea

There are a number of steps in the fermentation process. They include:

  1. Moisture is added to tea leaves so that Kuro-koji bacteria (the fermentation starter) will be more active. A blender is used to incorporate the moisture evenly.

  2. The wet leaves are sterilized with natural high heat steam to remove unwanted bacteria. After sterilization, Kuro-koji is spread equally to start the fermentation.

  3. Tea leaves develop heat during the fermentation process and a temperature sensor advises to mingle tea leaves if the heat exceeds a specified level.

  4. Once the fermentation level has been reached, the leaves are sterilized (high heat steam) again to stop the activity of the Kuro-koji. Leaves are then fired in a roasting machine to make them aromatic and flavorful and to keep the quality superior.


Dark Tea or Pu-erh Style Tea is known as "Diet tea". As we always mention, tea itself will not always drop your weight by itself, but it still might help! Dark tea has a special quality that green tea has but it seems to be more powerful than green tea. The fermentation process produces Gallic acid. This Gallic acid works with Catechins to unite with bile and to control its activity. Bile emulsifies fat and makes it absorb into your body. Thus Catechin and Gallic acid are thought to work together to block fat deposits into your body. This is explained in more detail in the following press release:

New elements found in microbial fermentation tea

Shizuoka News, March 23, 2011

Microbial research and development company "RIVERSION" located in Fukuroi City, Shikuoka-Pref (President: Denbei Kawamura ) has found two new polyphenols in its development of microbial fermentation tea. These two polyphenols suppress the diabetes enzyme of diabetes in adults. A joint research was conducted with Shizuoka University and Saga University. The Japanese Patent Office will publish this on March 24, 2011. Microbial fermentation tea is an innovative tea using a microbe scientifically confirmed not to make aflatoxin. It is a raw component found in Japanese Green Tea and during its process (moisture control sterilization - microbial fermentation), catechin is degraded and new polyphenols are created. These new polyphenols have been named "Teadenol A" and "Teadenol B". Tests of eighteen obese rats show that visceral fat, neutral fat and cholesterol have decreased and that weight has also been lowered in all eighteen rats. This microbial fermentation tea has also successfully passed food safety tests. Mr. Kawamura explained that "the raw material for this microbial fermentation tea is Green Tea which ensures a stable production throughout a year. In addition, tea with high catechin is suitable as raw material and thus the use of second flush green tea will significantly help Japanese tea farmers".


Pu-erh tea image

If you are familiar with a fermented tea, you might expect the taste to be a strong earthy flavor that you experienced with old aged Pu-erh however our Mori-machi Dark Tea has a toasty flavor with a hint of fresh greenish flavor and a little bit of a sour taste from the fermentation. This sourness actually becomes a habit for some Pu-erh lovers. Note that it does not contain alcohol even though it was fermented with a Sake fermentation method