Coffee Facts

What is Koji fermented coffee?

What is Koji fermented coffee?

Giving a whole new meaning to “moldy coffee”...


The world of coffee is always producing something new. Recently we discussed olive oil coffee. But certainly Koji coffee earns the prize for the most unique coffee beans of them all! Or at least the most unique as of right now. 


That is because Koji is coffee enhanced by fermentation. No, this is not like the interesting yet peculiar coffee mixes made with chaga, reishi, and other mushroom types, but rather a way of processing the beans. Of course, this one comes to us from you guessed it, Japan, few other coffee countries do things as cutting-edge and avant-garde as Japanese baristas do and so no surprise this is a Japanese export! There are probably many, many questions about this one, so let's dive right in, shall we?


What is Koji?


Koji (Aspergillus oryzae) is a type of mold that has been used in Asia for various culinary purposes. It is a mold that develops on rice and might be referred to as “rice mold”. The mold is then used to saccharify sweet potato, rice, and barley to make alcoholic beverages like shochu and sake. It is also used to ferment soybeans to turn them into miso or soy sauce. Without this important mold, many of our favorite Japanese and other Asian culinary delights would not exist or at least not be as tasty!


But how did koji coffee begin?


It all begins with the Japanese bioscientist, Koichi Higuchi. According to Koji’s origin story (we all know coffee origin stories function more as legends but this one is most likely fact-or so they say!), Higuchi had learned about kopi luwak. Mostly how the digestive systems of the civets act to ferment the coffee beans they eat via the enzymes in their stomachs. This led Higuchi to think of a cleaner, safer, and more humane method of achieving the same goal- fermented beans. So he tried sprinkling some koji mold on coffee beans and letting them ferment for a couple of days. He discovered that the fermentation had been a success and he had developed a whole new way to enjoy coffee beans.


How does it taste?


Though the idea of musty, moldy beans may be a major turn-off for most coffee drinkers, rest assured this is a mold of the good kind. Again, it's the ferment used to produce sake and soy sauce, not the kind that means for a spoiled bag of pre-grounds! The flavor and aroma palette for Koji fermented coffee beans includes softness, creaminess, a unique sweetness, and a certain complex character that must be brewed to be believed.


Koji coffee beans


Don’t turn your nose up on these beans. Because that’s not mold but rather a special cultured fermentation that enhances and amplifies the flavor, character, and overall experience of your coffee beans. And here we thought we had heard of everything in the world of coffee! Why not check out koji coffee beans? It will be one more unique take on coffee to cross off your coffee bucket list!


Works Cited

  • “The Impressive Rise of Koji-Fermented Coffee.” coffee, 23 Dec. 2021, Accessed 24 Apr. 2023.
  • Vittitow, Dominic. “What Is Koji Fermented Coffee?” Perfect Daily Grind, 31 Mar. 2022, Accessed 24 Apr. 2023.
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