Koji: In Search of a Slavic Umami

The inspiration for this curiosity project came from a place far away. 5475 miles, to be exact. This is the distance from my home kitchen to Noma’s fermentation lab – a place where creativity blossoms and the wildest culinary dreams come to life. Located in the capital of Denmark, Noma opened its doors in 2003. Since then, the team of insanely talented chefs from all over the world started reinventing Nordic cuisine, brewing, fermenting, and distilling native ingredients to extract the most intense flavors and create some unexpected textures and remarkable intensity. Under the fearless leadership of Chef Rene Redzepi, Noma became a center of innovation and a fermentation mecca not only for Scandinavian chefs but for tens of thousands of aspiring cooks all over the world. Myself included. 

Like many others, I became fascinated with Noma’s countless fermentation experiments. But one, in particular, caught my attention – unraveling the hidden depth of flavor using something I knew very little about – koji mold.

Koji, also known as Aspergillus oryzae, is an ancient mold that is responsible for making all kinds of umami pastes and liquids, including Japanese miso paste, soy sauce, sake, and Chinese fermented black bean paste, just to name a few. This divine fungus transforms everything it comes in contact with, giving the ingredients a complete makeover of texture, smell, and taste. 

Ancient China is considered the cradle of koji. Archeologists discovered that people there have domesticated the mold about 9000 years ago, using it for making alcohol that resembled ancient proto sake. Since then, koji became a treasured ingredient that helped shape Chinese and Japanese cuisines into the world’s most powerful umami empires.

Despite sounding like a fancy oriental ingredient, koji can be grown in any home kitchen using various techniques and devices: a food dehydrator, an immersion circulator, and even a DIY fermentation chamber built with a cooling rack, some thick plastic, and a forced-air heater, just to name a few. As long as you can provide koji with a warm, humid environment, with a temperature between 70 and 90 degrees with roughly 90 percent humidity, koji mold will quickly grow and flourish.

In Noma, they found dozens, if not hundreds, applications for koji. Using it for pickling native berries and vegetables, marinate and curing game meat, ferment grains and legumes into Scandinavian “miso” pastes, simultaneously creating myriads of unique flavors. Inspired by Noma’s extraordinary culinary adventures, I wanted to embark on my own exploration of finding a mysterious “Slavic umami,” and koji seemed like a perfect ingredient to start.

My Koji Journey

Slavic people were always skillful in domesticating wild yeasts and friendly bacterias. With the ever-present scarcity of fresh food, home preservations were among the essential mechanisms of survival. Given all the turbulences and external influences experienced by the Slavic cuisine, its signature flavors can be described as “acidic and fermented.” To this day, crunchy sauerkraut, malossol wild mushrooms, fizzy sour cucumbers, buzzy mead, and sparkling kvas are very dear to anyone who grew up in Eastern Europe. Even though Slavic fermentation’s history is centuries-long, people never got excited about an enigmatic flavor bomb called umami. For some reason, Slavs have never succeeded in creating their own flavor enhancers – amino paste and liquids like Japanese miso or Chinese soy sauce. Slavic cuisine lacks these basic condiments. All our umami attempts seem to be fully accomplished dishes on their own. 

The culinary world is moving forward, and now chefs are feeling more adventurous than ever, creating new flavors using age-old wisdom and techniques. With koji-pioneering restaurants like Noma in Copenhagen, Momofuku in New York, and Larder Delicatessen, and Bakery in Cleveland, and many others worldwide, it seems like chefs never stop innovating. That endless race for culinary excellence and exciting gastronomic discoveries might be the reason why I became obsessed with koji, which can intensify smells, boost flavors, and even improve textures without dramatically changing the original ingredient. Could that be the key to unlocking “Slavic umami”?

Step 1: Growing koji

Armed with Jeremy Umansky’s Koji Alchemy, Rene Redzepi’s Noma’s Guide to Fermentation, and Sandor Katz’s The Art of Fermentation, under the thoughtful supervision of chef Kirsten Goldberg, I started growing my first two batches of koji – barley and buckwheat. To be honest, I didn’t want to get my hopes high, but spoiler alert — it was a slam dunk from the first try!

Barley Koji


  1. To make barley koji, rinse and soak 1 cup of pearl barley for about 8 hrs. Then drain well and steam for 60 to 80 min. The grains should be soft but still very much al dente. Drain and pat dry with a towel. The grains should not be wet; otherwise, the mold will not grow properly (see Buckwheat Koji Note)
  2. Cool steamed barley to about 75 F and spread evenly on a clean kitchen towel. Place it in a metal container. A shallow ½ hotel pan with a lid works just great. 
  3. Mix 2 teaspoons of rice flour and a tiny pinch of Aspergillus oryzae (koji) spores. Sprinkle on top of barley and carefully mix with your hands to make sure the burley grains are fluffed and covered with koji. Note: use gloves as a precautionary measure to avoid introducing other unwelcome microorganisms.
  4. Loosely cover the inoculated grains with another kitchen towel and a lid and place them into an immersion circulator set up for 82F for 48 hours.
  5. After 24 hours, gently fluff the grains to prevent them from clumping.
  6. In 2 days, the grains will be covered with fuzzy white koji mold and will smell floral, fruity, and absolutely irresistible.
  7. At this point, you can call the final product barley koji. Brake it into small pieces with your hands and put it into an airtight container. Refrigerate until needed. Use it for making shio koji, amazake, miso, etc.

Aroma Profile: Pearl barley seems like it was created to grow koji. It produces beautifully even mold which smells pleasantly sweet, floral, and citrusy.

Buckwheat Koji

The process of growing buckwheat koji is virtually the same as for barley koji. The only difference is that buckwheat is a much softer grain and doesn’t require cooking. You can just soak it in water for 4 to 6 hours until smooth and plump. Then drain and dry well, and spread evenly on a baking sheet. Heat until the buckwheat reaches 75 F. Then repeat all the steps described for making Barley Koji.

Note: I used buckwheat imported from Ukraine. It’s toasted, has slightly larger grains, darker color, and tastes much more intense than the one I bought from the US producers. Make sure to thoroughly dry the barley grains. I didn’t do a good job the first day, and the koji mold had barely appeared after 48 hrs. After I changed the damped towel for a dry one, the mold formed in 24 hrs. It was slightly clumpier and stickier than the barley koji.

Aroma Profile: Buckwheat koji smell more intense than barley koji, with a hint of overripe fruits and a bouquet of intoxicating tropical flowers.

Step 2: Shio Koji

Shio koji is the simplest product you can make with your freshly grown koji. It’s basically just koji mixed with salt and water. You can think of it as an ultimate flavor enhancer that can elevate the flavor and improve texture. Shio koji is an excellent marinade for protein and a more neutral and briny alternative to amino liquids and pastes. Chef Cortney Burns, a famous cookbook author and a former co-chief of Bar Tartine in San Francisco, was one of the US’s koji pioneers. She marinated almost all proteins at her restaurant in shio koji, way before it became a cool new trend. 

Shio Koji Recipe:

For making shio koji, I used the recipe from Koji Alchemy (p. 117), a mixture of 1 part koji, 1 part water, and salt (5% of the total weight). Once you mixed all ingredients together, transfer them to a non-reactive container. Keep it at room temperature for 7 days stirring twice a day. After 7 days, the shio koji is ready. You can keep it in the fridge in an airtight container.

shio koji

Note: As I mentioned before, shio koji makes a phenomenal marinade for all kinds of protein. Using barley and buckwheat koji result in different shio koji flavors with their own distinct aromas, tastes, and intensity. Barley shio koji is fruity, floral, and mild; buckwheat, on the other hand, is intense, aromatic, and deeply savory. They are both equally great, but even when used on the same protein piece will produce very different flavor profiles.

Stage 3: Making Amino Paste

As a part of my koji experiment, I wanted to create some kind of Slavic miso paste. Instead of traditional Japanese soybeans, I used green split peas, which are native to Ukraine. I called this amino paste peaso. Before starting my barley and buckwheat peasos, I took a virtual workshop with Eleana Hsu – the founder of Shared Cultures – a new food startup that focuses on making modern misos, soy sauces, and amino liquids. It was exceptional, to say the least! Eleana is a real koji enthusiast. Her 1-hour koji crash course helped me understand the basics of miso making the principles of crafting vegan koji charcuterie and inspired me to use my koji for culturing butter and bread making. I also ordered her Shiitake “Soy” Sauce, Mushroom Amino Liquid, Lion’s Mane Modern Miso, and Fava Bean Miso to better understand different koji condiments and starting building my umami flavor profile library.

Proportions I used for my peaso: 

  • 125 g koji
  • 125 g kosher salt
  • 125 g cooked green split peas

Both of my amino pastes are still fermenting. I’m 8 weeks into the process. For a light paste, it can take from 2 weeks to 3 months; for a dark – 6 months to 1 + years) (Koji Alchemy p. 134)

Note: I tasted my amino pastes after 8 weeks and want to continue the fermentation for at least a month longer. I already can tell that barley peaso ferments faster and has a distinct fruity aroma. Buckwheat peaso goes slower but smells more intense and pleasantly funky.

Stage 4: Cooking with Koji

My curiosity project’s final stage was trying to incorporate koji into traditional Eastern European recipes and create a complete meal where every dish will have a koji product as a flavor enhancer. After thoughtful consideration, I crafted a full menu:

What’s next?

My koji journey has just started, but it has already showed me that the umami world is vast and beautiful, and the opportunities of integrating koji into Slavic cuisine are endless. I’ve seen just the tip of the iceberg, but I’m thrilled to continue my exploration. I want to grow koji on other native grains and compare their flavor profiles, experiment with chestnut and sunflower seed miso, tap into amazake and use it for making sour cream ice cream, and of course, make a lot of funky koji ferments. I will continue my research, and hopefully one day koji mold and it’s umami will become a part of Slavic culinary DNA.

  • Pingback:Koji Cultured Butter - Anna Voloshyna
    Posted at 19:42h, 07 April Reply

    […] Adding a little bit of koji to your heavy cream will create a wonderfully complex, nutty base for homemade koji cultured butter. It takes about 24 hr to culture and about 30 minutes to turn the liquid into a firm ball of rich and luscious butter you can enjoy right away. If you want to start growing koji at home check out my article Koji: In Search of a Slavic Umami. […]

  • Pingback:Mushroom Buckwheat Kasha with Lion's Mane Miso - Anna Voloshyna
    Posted at 19:42h, 07 April Reply

    […] If you want to start growing koji at home check out my article Koji: In Search of a Slavic Umami. […]

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