How to Make Koji 1: Choosing Tane-koji (Moyashi)

Marika Groen

February 17, 2022

Last October, American food professionals visited fermented food producers to deepen their knowledge of Japanese fermentation culture during the “Hakko Tourism in Japan” tour campaign. As part of the tour, organizers held a tasting session where guests gave candid advice from the perspective of the American market to food product manufacturers looking to enter the United States market.

Today we finally start talking about how to make koji. To begin with, you are going to need a starter. Remember that koji is a fungus, so the starter you need is actually a collection of spores of the fungus. We call this tane-koji or moyashi. The koji fungus itself, we call it koji-kin. In the first issue I briefly mentioned that koji-kin that we commonly use in Japan are:

  • Aspergillus oryzae is used for a wide range of applications such as sake, miso, soy sauce, mirin etc.
  • Aspergillus sojae is for soybean-based applications
  • Aspergillus luchuensis kawachi and Aspergillus luchuensis awamori for shochu
So we basically have only three varieties of tane-koji? No. There are also spore colour differences depending on whether they are albino strains or not. That’s it? No. Imagine a bag of carrot seeds. They all are called carrot seeds, but in fact, each seed is different and has a slightly unique character. Imagine us. We all are called humans but each one of us is different.
Koji-kin is also a group of different talents. Not only they are classified as A. oryzae or A. sojae etc, but also every single one of them has a unique talent, different from each other.
Tane-koji (moyashi) in a strainer
Take Aspergillus oryzae, the most standard one for example. You see that this can be used for many applications, but for sake making and for miso making, we chose different blends. In fact, every sake or miso producer has a different preference in blends on this koji-kin, because the substrate, the water, the environment and the way they work with koji are all different. This explains the reason why it’s extremely difficult to make exactly the same koji even if they use the same tane-koji.
On top of that, we have many choices even within A. oryzae. Some tane-koji is designed for shiro miso, the lighter, sweet type of miso, thanks to its superior talent to break down the carb into more sugar and the ability to keep the koji white (albino strain). To make mame miso on the other hand, we have different tane-koji that is designed to break down the protein more into amino acid, expecting more umami in the final fermented product. Some are suitable for barley koji making, some are for amazake, and some are even a blend of several different talented strains to meet the desired complexity of the final flavor. If you talk about the varieties of tane-koji for sake making, you will drown in too many choices.
That says, precisely speaking, you need to know what you want to use your koji for before deciding on the tane-koji. Of course, you can just try the multi-purpose tane-koji to practice, then be more specific as you are acquainted with this custom of koji making successfully in your life.
Each tane-koji maker in Japan also has a different strength and a catalogue to showcase their expertise. Of course, the all-purpose tane-koji for your start-up, too.
Excited? Get your hands on your first tane-koji, and see how far you can play with one strain. That will already take years of fun learning to you.
Tane-koji (moyashi) on a plate
Malica Ferments | + posts

Marika Groen is the head of Malica Ferments, an online platform dedicated to fermented products. As a Kojiologist, traveler, brewer, photographer, and writer, she published the book "Cosy Koji" in 2021, offering insights into the art of Koji making based on her worldwide lectures and experiences.