Amazing Koji Mold World: 45
Pickled koji – Part 2

Written and illustrated by Misa Ono

In Japan, there are many kinds of pickles with koji (or chili pepper). Pickling with only salt makes the ingredients just salty, while with koji, it adds the sweetness and umami, as well as good shelf life. Koji-pickled salmon, herring, cod, sea squirt, deep-water shrimp, etc… all of them are sweet but salty, and rich in seafood flavor! It is great company to steamed rice and sake! My favorite is koji-pickled dried squid. To make this, chop the dried squid into a bite size, mix it with koji, sake, mirin and soy sauce, then leave it for 1 to 2 weeks. The flavor of the squid and all the seasonings are absorbed by the squid making it tender. Another great thing to go with sake! Am I drinking too much?


Koji-Pickled Dried Squid
Photo by Shinichiro Nagasawa

One of the unique pickled dishes is called “Fugunoko no nukazuke”, which is salt-pickled pufferfish’s ovary. The pufferfish’s ovary contains a deadly poison. However, when the ovary is pickled in salt for over a half year, 80% of the poison is detoxified. Moreover, when it is pickled in rice bran and koji for a year and half, the poison completely disappears. What magic! It is very salty, but the rich-flavored roe goes well with rice and sake again, and can be used for pasta too.


Fugunoko no nukazuke – the pufferfish’s ovary is pickled in salt.
Photo by Shinichiro Nagasawa


Fugunoko no nukazuke
Photo by Shinichiro Nagasawa

Koji is a very useful ingredient as it can be used for seasonings, drinks and pickles, but not only them, koji also ferments tea leaves. The tea called “Goishi cha” is very rare in the world since it goes through two fermentations process.

After steaming the tea leaves, place them onto a straw carpet called mushiro, then cover it with another mushiro. Koji mold living in mushiro starts to ferment the leaves gradually. Put the fermented leaves into a wooden bucket, and pour the water that comes out when steaming, then cover it with a heavy stone. This time, the lactobacillus starts to ferment the tea leaves. 20 days later, cut and dry the leaves and it is ready to drink. It takes time and efforts to make this tea. It is sour and bitter so some people wouldn’t like it like I do. But it is a very nutritious tea, thanks to that bacteria.


Goishi cha. Photo by Shinichiro Nagasawa


Goishi cha. Photo by Shinichiro Nagasawa

In the humid climate of Japan, many types of bacteria exist including the good and bad ones. People found these bacteria when microscopes weren’t invented yet, and they’ve been coexisting until today. It is not only in Japan, but all over the world. Koji mold, however, exists mostly in Japan and Japanese people have been creating their own flavor with the mold. Take sake as an example. Without koji, rice and water will stay as rice and water, and never turn to sake. Bacteria and molds are very interesting creatures. I hope you now know more about koji and take it into your diet more often. Thank you very much for staying with me and reading through all my columns!