Tony Zentgraf
Learning Koji & Miso making with Midori Uehara owner of Mido‘s Miso
Midori Uehara is an artisan of her craft and is very skilled at making Koji and Miso! Let’s learn the fascinating process of making Koji which is the key to Miso and so much more!
Topics in this Post – Exploring the Source with Mido’s Miso
- International Studies to Miso Maker
- Miso: Three Ingredients = Umami
- Koji, Never Heard of It
- Koji Fungus – The Backbone of Japanese Flavors
- The Process of Inoculating Rice
- Steaming vs Rice Cooker
- Cooling & Inoculating the Rice
- Putting the Rice to Bed
- Preparing the Koji for Miso Making
- Koji’s Importance in Cultural Heritage
- Recipes with Mido’s Miso and Koji
- Find other Exploring the Source Interviews
Jump to Video Interview
International Studies to Miso Maker
Midori Uehara settled in Oregon after completing her degree in International Studies in Japan. Prior to her university studies in Japan, she had been part of international exchange programs that allowed her to visit and live in Canada and the U.S. She studied in Montana, worked at Disney World as a Teppanyaki chef at Epcot before attended university in Wisconsin.
While in Wisconsin, she began feeling homesick. This is where she discovered her comfort food, MISO! At this point she began making her own miso and eating miso soup as a daily meal.
Returning home to Japan after her studies in Wisconsin she then completed her Degree in International Studies. Afterward, she wanted to return to the U.S. and eventually settling in Eugene, OR. This is where she met her partner and later moved to Cave Junction, OR.
Miso: Three Ingredients = Umami
Miso is made with three ingredients – a type of bean (typically soybean or chickpea), salt and Koji. These ingredients are ground together to a paste. They are then stored in a container for a year or more Depending on the type of miso (Shiro Miso, Aka Miso or Awase Miso or others) the time fermented can vary. See the recipe for Miso Glazed Salmon for more on Miso.
Not to downplay making miso or its health benefits, but miso wouldn’t be miso if it wasn’t for Koji. So I am going to focus on the interesting process of making Koji from here on out. Without Koji we wouldn’t have Miso, Soy Sauce, Rice Vinegar, Rice Wine or Sake as ingredients, Not to mention many other Japanese foods.
Koji, Never Heard of It…
When met Midori, I had limited knowledge of Koji, how it is made and all its uses. Before meeting with Midori to film the interview, I did research on Koji. It brought some light as to what Koji is but the uses of it were still to be learned. As you will see, the process of Koji making along with its uses, plays a vital role in Japanese cuisine.
If you are not familiar with Koji, it is really the backbone of Japanese condiments: Soy Sauce, Mirin, Rice Vinegar, Rice Wine, Amazake and even Sake but its uses go beyond condiments and alcohol. Japanese food would not exist how we know it if it wasn’t for Koji.
Koji Fungus – The Backbone of Japanese Flavors
Koji fungus, otherwise known as Aspergillus Oryzae, is a mold that forms on rice plants. As the rice plants mature, the mature plant droops over due to the weight of the rice grains. The rice, if left to sit, will begin to grow fungus. These fungus spores have been cultivated over 1000 years, because of this, Koji has evolved into many ingredients vital to Japanese foods and methods of preparation.
Koji spores are no longer harvested from the rice plants in the wet paddys. Instead, as Midori explains, there are only about 10 Koji spore companies in Japan, of which these companies each have their own strain of Aspergillus Oryzae with over 100 varieties of the fungus.
Some of the different spores are better at breaking down protein while others are better at breaking down carbohydrates into simple sugars. While others work to break down both.
Midori uses a Koji fungus that breaks down more carbohydrates which is why her types of misos are sweeter than others you may have tried.
Try making your own Koji rice!
Pick up some Koji Spores to inoculate rice to see the process for yourself!
The Process of Inoculating Rice
Koji has traditionally been inoculated on rice, soybeans and barley but depending on the type of medium you are wanting to inoculate, there are different types of spores for each.
In the southern region of Japan, barley crop is harvested. Rice is grown in the central region and soybeans in the north. Each region has their own variety of miso based on the region’s crop being used as the ingredient in Koji making.
The majority of miso made in Japan uses rice as their medium for growing the fungus to make Koji. Since Midori makes Koji made from rice, let’s discuss how this 3 day process works.
Rice is soaked overnight to soften, the next day the water is drained. Midori demonstrates how to know when the rice is ready to proceed to the next step. She rubs a grain of rice between her fingers. If the grain of rice breaks apart and becomes rice flour, the rice is ready to be cooked.
Steaming vs Rice Cooker
Midori steams the rice instead of cooking in a rice cooker because a rice cooker will add too much moisture to the rice. Once the rice is steamed, the rice should not be overcooked.
The grains should be loose and not clump. When the rice is mashed together in the palms of your hands, it should stick together and have a similar texture to mochi, having some elasticity.
Cooling & Inoculating the Rice
Cooling the rice is very crucial in the inoculation process. As demonstrated in the video, her crew uses a special technique to move and fold the rice to reduce the temperature of the rice to below 32° C (89.6° F). This is the optimal temperature for the Koji fungus to grow on the cooked rice.
Once cooled, the rice is ready to be inoculated with the spores. Because the Koji spores are so light, they are mixed with a secondary ingredient. Typically a flour such as a brown rice flour is used. This allows the Koji spores to have some weight that will allow them to fall onto the rice instead of blowing away. Using the brown rice flour gives the Koji spores some nutrition as well to help them grow.
The spores are sprinkled over the rice a few times, during the process, the rice is mixed by hand between each batch of Koji & brown rice flour mixture is sprinkled. This is done to ensure that each grain of rice has some of the Koji fungus.
Putting the Rice to Bed
The rice is packed into pans lined with special cloth; the cloth is then folded meticulously to ensure the rice is kept moist.
Midori uses a bread proofer to keep the rice for the next 48 hours. The rice is kept at below the 32° C, the ideal temperature for growing the fungus and a specific humidity level to retain the moisture needed for the fungus to develop.
The first 12 hours the inoculated rice spores do not need much oxygen. By not being disturbed, the fungus and rice are allowed rest providing a base for good growth on the rice. After the rice is put to bed and rested, it is fluffed and folded three times over the next 12 hours. Mixing the rice the next day gives the fungus growth more oxygen, getting them to grow quickly.
Two days later, when the rice is removed from the climate controlled box, the steamed rice has transformed into Koji.
Preparing the Koji for Miso Making
Once Koji has been completed, the Rice Koji is broken up, back into individual grains. This will allow it to be better incorporated with the beans and salt to make miso.
Koji’s Importance in Cultural Heritage
Because Koji is such an integral part of Japanese food and culture, Koji fungus has been designated a National Mold. 1
In addition to the national status, the Traditional Knowledge and Skills of Sake-Making with Koji Mold in Japan is up for nomination with UNESCO World Heritage for 2024. 2
Washoku, traditional dietary cultures of the Japanese, notably for the celebration of New Year has been accepted into UNESCO Intangible World Heritage. Because Koji goes back over 1000 years and is ingrained into Japanese food, it falls into this category of world heritage for UNESCO. 3
A Big Thank You
I want to thank Midori and her crew for letting me see behind the scenes of her business and teaching me the process of Koji and Miso making. Not to mention, teaching me about the history behind Koji and why it is such an important ingredient in Japanese food.
Recipes with Mido’s Miso and Koji
- Shio Koji Marinated Pork Tenderloin
- Miso Soup
- Miso Salad Dressing
- Miso Glazed Salmon
- Apple Frangipane Tart with Miso Caramel
Exploring the Source interviews Midori Uehara of Mido’s Miso
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