
When it comes to Japanese ingredients, koji is one of the most versatile and misunderstood food products out there. I like to think of it as the Batman of the fermentation world because it’s the hero mould we need and deserve. It elevates everything it comes into contact with and makes food and drink more delicious.
So, it’s always great to see more brands spreading the koji love and that’s the case with Koji Soupe. I caught up with owners Yota and Noriko Suzuki, who are on a mission to bring more koji awareness to Montreal.
Read on to learn more about the business, what got them interested in fermentation and where they see the future of Koji Soupe.

Great to chat to you Yota and Noriko and to learn more about Koji Soupe. For people who aren’t familiar koji, how would you describe it and how does it factor into your brand?
It’s a pleasure to have an interview with you. Koji is a traditional and essential ingredient for producing miso, sake, soy sauce, and other Japanese condiments in Japan’s unique food culture.
It is made of cooked rice that has been inoculated with Aspergillus oryzae, a mould that’s widespread in Japan. Obviously, koji mould is totally harmless, and safe to eat.
So, basically, koji is a fermented mouldy rice. Koji is not eaten on its own but used to cook and marinate food.
As a demonstration and for our branding, we cook ready-to-eat meals prepared with koji. This preparation brings out the flavour (umami) from the ingredients. Especially, for the soup with meat, you would see the tenderness of the meat!
We also make amazake cheesecake, with almost no sugar added in it.
What was your first experience with koji and how has it inspired your approach to cooking and food preparation?
Our first experience with koji was that we made amazake at home. It was very impressive since it was so sweet even though there was no sugar in there. Since then, we approached it like a vegan baking substitute.
When we bake pastries, we try to reduce sugar as much as possible but not lose the satisfaction of the taste. The sweetness of amazake is coming a little later than other sweet ingredients.
Having combined with amazake and other sweets (such as honey and maple syrup), your baking becomes richer in flavour and unique in sweetness.
On your website, you’ve stated you’re on a mission to raise koji awareness in Montreal and beyond. Why do you think it’s not as well-known as other Japanese ingredients like shoyu and miso?
We feel koji is still not well recognised here, and to apply koji to your cuisine still needs a bit of technique of fermentation. Although we brought koji production in Montreal, it was actually within expectation that it is hard to disseminate the potential of koji among Montrealers.
In fact, almost all Japanese use soy sauce and miso but not everybody uses koji in their cooking. However, once you know how to use and its beneficial aspects, you would stick with koji.
So, our mission is to do a good job explaining about koji and marketing it. What we are doing now is that we made a couple of brochures (we called it text book) about what is koji and how you can use it in your cooking.
We strongly believe that once people get familiar with the different ways to use koji, as well as its benefits in taste and for health, it will become more popular. Hopefully our soup and desserts can be the first step for them to experience koji.
In recent years there’s been a greater push to raise koji awareness, especially with NOMA in Copenhagen and Jeremy Umansky with Koji Alchemy. Are there any other people or businesses you’d recommend checking out for their focus on koji?
Tonoya-yo is one of the koji restaurants we’re eager to visit. They are actually an auberge (inn) brewing and serving homemade doburoku to the guests.
As you know, doburoku is not as tasty as nihonsu in general, but when we had their doburoku in the nihonsu bar in Tokyo, we fell in love with it.
It was full of fruitiness in flavour and very elegant in the taste. The auberge used to be an ancient accommodation, then turned to an exclusive auberge where it serves premier grade doburoku, and all the dishes served are fermented.
As they focus on the best service and dining experience, only 1 group can be hosted in a day! Hopefully we can visit there on our next trip to Japan.

How do you go about choosing your koji products and deciding on what is most suitable for people who are new to it?
It really varies and depends on what we want to do. In fact, we have a wide variety of koji spores that can be used for a wide variety of products. For example, for the most popular products like amazake, sake and fermented sour koji, we use 2 kinds of spores which are very simple and easy to use for those people who are new to koji rice.
What techniques have you been using to bring your products to people in lockdown?
During the pandemic in 2020, we came up with the idea of a shared kitchen with a local business. So, we don’t have an actual store, but we do deliver our products.
We also agreed with some restaurants and cafes to pick up your order.
Outside of Japanese food, what kind of dishes would you recommend using koji with?
An example of use of koji outside of Japanese food would be Tandoori chicken. Koji enzymes work to dissolve the protein under the marination process and the fermentation will be stimulated with yogurt.
Another idea is duck confit. As it is cooked with low heat temperature, koji enzymes stay active during the cooking process. Eventually, the meat is tenderised and the umami taste elevated.
Using koji is actually an art form. It depends on the chef’s creativity. Like NOMA restaurants, there will be more alternative usage that the creative person can come up with.
We are very excited if customers would share their own recipes using our products!
Where would you like to see Koji Soupe in five-years’ time?
We hope that shio koji and amazake can be as common in the fridge of Montrealers as mayo or ketchup.
We are planning to host more events such as webinars or home brewing. As we mentioned in the beginning, koji has lots of potential. It’s well known for improving gastro issue and improving skin condition and we’d like to become a hub of koji knowledge for our customers.