What’s the difference between the fuzzy mold that grows on leftovers forgotten in the fridge and the mold koji that creates the umami-rich flavors soy sauce and miso? Controlled growth.
“That’s an important parallel,” says Rich Shih, the koji guru behind Our Cook Quest and co-author with Jeremy Umansky of the book “Koji Alchemy.” Shih spoke during a recent webinar hosted by The Fermentation Association, “Demystifying Fermentation — Learning to Love Mold.” “You create these very specific conditions where the components are food safe…they’re made in a fully controlled, clean environment…when you allow it to go through a fermentation process, it ends up being preserved in a way that is delicious and nutritious for us. That’s the key to fermentation in general. What’s nutritious and delicious to us is a result of these microbes that we persuade in this specific direction to create a circumstance that’s pleasing to us.”
Koji is also known by its scientific name, aspergillus oryzae. Incubating it, Shih says, creates a “blank slate” for the koji spores. He compares it to adding yeast to a bread or beer.
“We’re basically leveraging their ability to be able to do this work on an exponential basis to yield something for us because they’re trying to survive based on the food stuff we give them,” Shih says, explaining the koji fermentation process. “But we’re introducing them to this pool of wonderful, delicious things that they get to convert — and then we take the benefits.”
More chefs are experimenting with koji as a seasoning or marinade. It is empowering and easy to incorporate into dishes, Shih adds, noting: “Once people realize this, koji is really going to explode.” He recommends beginners start with a koji paste.
Alex Lewin, moderator of the webinar, author of fermentation books and TFA Advisory Board member, agrees. He compares koji to the medieval alchemy of the philosopher’s stone, which could transform lead into gold. Koji mold is transforming ingredients into flavorsome food.
“Where bacteria and yeast are very specific and narrow in focus, koji and mold in general have a much broader set of capabilities,” Lewin adds.
Shih shared one of his latest koji kitchen experiments: a cucumber sorbet. He added koji spores to the cucumber, then froze it for a texture similar to shaved ice. He stressed koji “can be a seasoning for any food, regardless of preparation, locale or cuisine. It’s easily translated.”
“Koji, basically it’s magic,” Shih says. “It really changes the game overnight in terms of the flavors you get out of it. It opens a whole world of possibilities.”
Most people are familiar with koji and don’t even know it, Shih says. Koji is an ingredient in soy sauce, a common condiment in home pantries. There’s a huge commercial industry for soy sauce. But Shih says people should learn to experiment with koji outside of a soy sauce bottle. He points to artisan cooks and chefs, who take control of their food by sourcing ingredients from local farms. By fermenting them, they create nutrient-dense food with a long shelf life.
“That’s the gap we fermenters are encouraging people to bridge. You have the power to create nutrition in a way that you enjoy ingredients in your locale,” Shih says. Follow some simple rules with koji and “it’s really hard not to make it taste good. If you know how to boil water and mix things, you can make something super delicious, and that’s empowering.”