“Cosy Koji”: Marika Groen and Melissa Mills on the Making of a Koji Community

In the world of home fermenters, Marika Groen’s Malica Ferments—built over the course of eight years from her base in the Netherlands—stands out as a uniquely warm and welcoming community. When Covid-19 shut down her in-person “Kojiology” classes, her following went global, producing Cosy Koji, a small, lovingly made handbook on koji-mai, the mold-inoculated rice that is the starting point for a galaxy of fermented foods, from miso, shoyu, and mirin to sake.

Portrait of the kojiologist.

The book’s quirkiness starts with its cover byline: “You and Marika Groen of Malica ferments … plus all of the collective microbes around us.” At first I thought “You” might be Marika’s European partner with an unusual first name.  Instead, she explained, “You” refers to the reader, because when she began the project she had the “strong wish to ‘grow’ this book together with the people around me.” She didn’t want it to be complete in any sense, but to show readers how “the more you dive into koji, the more paths you see,” both within and without koji making. Her hope is that the book continues to grow in the hearts and minds of readers.

“Koji has its own life, not so different from yours,” the book explains. “They are born, grow up, learn to survive, and pass away in the blink of an eye.

“Their purpose in life is not necessarily to deliver nice miso or sake to us, but to simply live their own life and to play their own roles. How would they know what they are meant to do? We can say that it’s programmed in their genes, but let’s be romantic – they know that they are merely a passing star that comprises the larger living matter in this world. They are born with talents and characters, which can transform depending on what they eat, how they are nourished, and what environment they grow up in. How we can communicate with koji is, in fact, to quietly observe their progress, to encourage their potentiality, and eventually to see them to the end of their life. We can only follow their trail and let go. How do you feel about that?”

Harvesting koji in Kojiology class.

I’ve noticed that koji making tends to elicit this sort of anthropomorphic idealism from makers, probably because of the way it operates on the plane of interdependence and transformation, both of which seem to hold so much positive potential. Making koji is about the creation of life, deliciousness, and beauty out of nothing. In reporting our sake book, I came across numerous comparisons of making koji--and by extension sake--to the nurturing act of parenting or caretaking. Midori Okazaki, a woman toji from Nagano’s Okazaki Jozo, thinks of her fermenting tanks of sake as her children in the way that for both little humans and sake, she tries to bring out their latent positive qualities and keep their less desirable traits at bay. Tadashi Onishi, owner-toji at Kiyasho Shuzo (makers of the Jikon brand), has described his role as essentially that of a koji farmer. Koji can make us feel better about ourselves and our role in the world and make the world a more welcoming place. In Groen, this agent of change has found a sensitive interpreter and champion.

"It Happens Anyway" exhibition in Amsterdam.

She assembled an eight-member team from Japan, Spain, France, Germany, Australia, and the U.S., which contributed design, editing, photographic and koji-making talents, creating a 108-page, beautifully photographed book. (The number 108 is significant in Buddhism as it refers to the number of earthly desires and human feelings, among other things). The book takes you through the equipment you need to make koji, offering a step-by-step guide. Included is a section on the various types of tane-koji, (seed koji, or koji spores), and where to buy them, and rice varieties from around the world that can be the starting point for koji making. I found the book less intimidating than other koji-making guides, and appealingly scaled to the beginner at home who wants to start with a small batch of between a half to one kilo of rice. There is a section on making koji using other substrates, including soybeans, barley, and even oatmeal.

Groen’s interest in fermentation began when she realized that there were no home-based or even local chef koji or miso makers. She began teaching herself fermentation techniques, first making miso with commercial koji rice, then branching out to making her own koji-mai. Fermenting foods was a kind of solace to her, bringing her closer to the Japanese traditions she grew up with.

Koji on the move.

She began visiting Japanese makers of miso, mirin and shoyu, gaining valuable knowledge along the way. Today her global network is impressively far-flung, connected to koji-kin (koji fungus) makers across Japan; sake breweries including Terada Honke Shuzo in Chiba Prefecture and Sawada Shuzo in Aichi Prefecture; shoyu, miso, and mirin makers, and the fermentation lab at Noma in Copenhagen.

Groen describes assembling her team, which included just two native English speakers, and the challenge of capturing thoughts not easily expressed in words.” Often its language is inadvertently apt and charming: A description of the different types of tane-koji refers to the  variable “hair styles (short or long mycelia)” you can look for, depending on the outcome you want.

Melissa Mills and Terada Honke Brewery toji Masaru Terada giving a doburoku demonstration near Melbourne in 2019.

One member of Groen’s team is Melissa Mills, the New Zealand born, Melbourne-based sake educator and consultant, who transformed herself from dental surgeon to sake expert. She began home brewing sake in about 2018 after reading Nancy Hachisu’s book Preserving the Japanese Way. Her love for Terada Honke Brewery’s Daigo no Shizuku led to an interest in the ancient bodaimoto method of brewing, and she began making her own version of bodaimoto, following guides ranging from Sandor Katz’s “Wild Fermentation” blog to a recipe from Koji for Life, by Tomoyuki Nakaji, formerly head brewer at Terada Honke.

When Mills stumbled upon Groen on social media she was struck by how this Japanese woman was sharing knowledge so freely and generously in English. Unlike some artisans who “preserve and hold secrets they don’t share,” she notes, Groen “tries to explain a lot of the deep knowledge and spiritual aspects, but also technical things” that Japanese practitioners might take for granted.

Mills spreading out rice to be steamed at Sekiya Jozo’s Ginjo Kobo small-batch brewing facility in Aichi Prefecture.

In 2020 Mills started a Facebook group called The Sake Brewing Collective. “I thought I would get twenty people,” she recalls; today it is made up of nearly 600 members. Mills took Groen’s “Kojiology” class, which boosted her confidence. Sake making, she learned, is recipe-driven, so the inclusion of recipes in Cosy Koji was important to the team.  Mills helped write the section on doburoku in Cosy Koji, which includes a meticulously written recipe that I can’t wait to try. And the bonus of making doburoku at home is that if you decide to strain the moromi (you also have the option of enjoying it in its original, more porridge-like consistency) you will then have your own sake kasu lees, which can be used for all kinds of interesting marinating, grilling, cooking, and baking projects.

Queen's Meadow Country House, Iwate Prefecture.

Groen has found that her adventures with koji have not only expanded her world but led to a healthier lifestyle and improved wellbeing. Making koji to her is a process of “discovering your own potential, realizing that everything necessary is within you.” She advises novice koji makers to “take a moment to feel the time and space and experience of it,” adding, “It will definitely enrich your life and lead to a healthier community around you.”

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