We're often told that mould is the enemy, a sign to throw food in the trash. But some forms of mould are special, and Aspergillus oryzae, or koji, might be the most special of all. It's a crucial ingredient in dishes such as scallop with mould-fermented bread broth, currently at the vanguard of Canadian cuisine.
In Japan, this particular fungus is known as koji, and often referred to as the country's national mould because of its role in brewing sake and breaking down the starches and proteins in simple soybeans to produce umami-laden miso. It's now becoming a favourite tool of non-Japanese chefs in Canada and around the world looking to expand their pantries and explore new flavours.
Antonin Mousseau-Rivard, chef of Montreal's Le Mousso, has long had great admiration for Japanese cuisine. "I've been going to Japanese restaurants since I was a month old, so I think it's part of my influence," he says. "But we try to use koji as a technique more than a traditional ingredient."
Recently, he found himself staring at leftover bread, dreading the countless bread puddings he made while training in hotel kitchens. "So we took our bread, smashed it up and then we treated it like it was dehydrated beans that we'd make a miso out of," he recalls. The chef considers it "the best-tasting miso we ever made," and he used it to create a broth with which to surround a perfect scallop.
Miso made out of local ingredients such as peanuts, black walnuts, barley and split peas also shows up at places such as Actinolite in Toronto.
"When you've cooked a beet for three or four years, it gets a little redundant and you start trying to see what can we do to make it a little tastier," chef Justin Cournoyer of Actinolite says. "So two years ago I decided we had to try to make miso."
He and Mousseau-Rivard both point to chef René Redzepi of the Copenhagen restaurant Noma as an inspiration for delving into the world of koji, as well as David Chang of the New York-based Momofuku restaurant group, who has famously crafted "American" misos out of chickpeas and sunflower seeds.
Chef Justin Cournoyer, owner and chef of Toronto-based Actinolite, uses koji to help break down meat trimmings into a product called garum. Cournoyer says he likes how sustainable the practice is. ‘It’s taking a byproduct that I really didn’t know what to do with and creating another pantry item.’
Branded as " Hozon," these are now sold to restaurants across the United States, helping spread the word about the umami-boosting powers of koji products. Like Chang, Jeff Kang of Toronto's Canis is of Korean descent and notes that his family's food culture has many similarities to that of Japan, including the use of koji to make things such as miso and other fermented flavour enhancers.
Kang has been exploring the many ways koji can be applied to provide unexpected flavours to the dishes at his year-old restaurant, which is focused on seasonal Canadian cooking. "We don't make Japanese food," he explains, "but Canada's a multicultural country and we want to show that Canadian cuisine isn't just poutine."
In the same vein, koji is not just used to make miso. All three chefs also use koji to help break down their meat trimmings into a product they call "garum," borrowing the name of an ancient Roman fermented fish sauce. To make meat garum, trimmings, koji and salt are combined and left to ferment like a traditional miso, but with animal protein in place of soybeans.
"What I like about it is it's so sustainable, it's taking a byproduct that I really didn't know what to do with and creating another pantry item," Cournoyer explains.
And a delicious pantry item at that. "We ended up with this really unbelievable flavour paste that tasted like the soul of 100 wagyu cows," Mousseau-Rivard says, describing his beef garum. "It ended up in a sauce that we just brushed over a lightly cooked oyster like sushi. And it was truly out of this world because beef and oysters always go well together and usually garum would be made with oysters in the first place."
Moving further afield from traditional Japanese applications, chefs are now also experimenting with using koji to age prime cuts of meat. At Canis, Kang has cultured it directly on the surface of a pork loin roast, while Cournoyer and Mousseau-Rivard have both used it to help cure charcuterie.
Despite this array of potential uses, koji isn't a miracle mould that can almost turn water into wine. At least not in just any hands.
It’s not only traditional Japanese chefs who look at the growing prevalence of koji cookery with some skepticism.
"Using koji is not a common practice for chefs in Japan," asserts Masaki Hashimoto, one of Canada's most celebrated kaiseki experts and chef at Toronto's Kaiseki Yu-zen Hashimoto. Instead, he says, chefs typically rely on experts to make the highest-quality miso and soy sauce, often seeking out artisan producers who have produced that one product for generations.
Chef Seiichi Kashiwabara of Markham, Ont.'s ultra-traditional Zen Japanese Restaurant also cautions newcomers to the ingredient. "I think it is good for other chefs to experiment," he says, "but it does take a high amount of knowledge and skill to do properly and perfectly, which is something that is commonly overlooked."
It's not only traditional Japanese chefs who look at the growing prevalence of koji cookery with some skepticism. Cournoyer may be one of koji's biggest Canadian advocates, but even he worries about it becoming this generation's foam. "Yeah it's a trend, but why do we use it? You always have to question if it makes sense," he says, "and I don't think all chefs know – they just do it because they see it on Instagram."
Knowing he needed to truly understand koji if he wanted it to make an impact in his dishes, Cournoyer enlisted help from a friend with scientific expertise before he made even a single miso. He knew that koji is not just a trend but an actual living organism and it takes dedication to decipher its best uses.
"We had a lot of failures early on," concedes Kang, but through a process of trial and error fortified by research, he and his team now have a base of recipes that consistently deliver unique flavours to diners. Mousseau-Rivard has plans to add a dedicated fermentation lab to the new location of Le Mousso that's slated to open early next year. "These Japanese techniques are really practical and ancient proven techniques," he says. "There's a scientific process – you have to have the right temperature, the right humidity, the right combination of ingredients."
By applying rigorous scientific methods to his koji cultures, Mousseau-Rivard hopes to develop the expertise and knowledge Japanese chefs such as Hashimoto and Kashiwabara say is so important, while also creating new recipes that draw on Japanese technique but speak to his personal experience living and working in Montreal.
"For us, it's only natural to take influence from every country that has imparted a bit of knowledge into ours," Mousseau-Rivard explains. And through that prism, what's more natural than using a little Japanese mould to help transform local ingredients?