[Ed note: After Cynthia Graber delivered her koji story to the Cook’s Science team, Associate Editor Tim Chin began developing his own recipes for the home cook. The following is from his perspective.]

Coming into this project, my only experience with koji involved marinating and pickling foods in shio koji, a combination of koji rice, water, and salt that is allowed to ferment for at least a week to develop a fruity, sweet, slightly funky aroma. I was a newbie. Culturing koji directly on meats was an idea totally foreign to me, so I decided to nerd out. After talking to our writer Cynthia Graber for some initial ideas, I read as much as I could about inoculation and incubation, traditional and modern techniques, and koji’s deep culinary history. I even joined a koji enthusiast group on Facebook, lurked for a while, and started conversations with fellow koji students. Eventually, I came into semi-regular correspondence with Jeremy Umansky himself—a.k.a. Koji-Wan Kenobi (a self-ascribed, yet fitting nickname). Under his guidance, and after a lot of sketchy-looking mold, I was well on my way “down the rabbit hole,” as those in the koji community like to say.

I divided my development into recipes using shio koji as a marinade and recipes involving culturing koji directly on foods. I started by cooking different meats and fish marinated in various brands of store-bought shio koji. Many of the store-bought brands of shio koji tasted like they were full of fillers—sugar, mirin, sake. Because of that fast-browning sugar, all of my attempts were burnt, and none of them were all that good. As a result, I decided to skip the store-bought stuff and make my own from firm granular rice koji. Luckily, I found a number of high quality, pre-cultured and dried koji rice products available on the web. I ordered them all.

A few weeks of fermentation and goopy rice later, and we had our very own shio koji to use. This stuff was amazing: It was great on its own, or sprinkled straight on eggs or rice. But as a marinade it proved even more valuable. Because shio koji is rich in enzymes called proteases that break down proteins into flavorful amino acids, it quickly tenderized meats, turning them succulent, juicy, and savory. After some initial testing, I settled on developing a fried chicken recipe because 1) I was inspired by Jeremy’s mention of it in his TED talk as well as Angela Dimayuga’s version of it on Munchies 2) I wanted to showcase the radical transformative properties of shio koji and 3) I freaking love fried chicken. And so for the better part of four weeks in development, my team was treated to the juiciest, most sweet-savory and satisfying chicken we’ve had in a while.

While working with shio koji proved successful, my work with inoculation and culturing was mixed—and mostly an exercise in frustration. Adapting a recipe for growing fuzzy mold on something for the home cook is a tough sell no matter how you spin it. But to me, this was where the most interesting and enriching ideas resided, at the frontier of culinary applications for koji. And so I trudged on—motivated by the amazing work that people in the koji community were doing and encouraged by Jeremy’s assurance that, “It’ll grow.”

To successfully incubate koji, I needed to maintain an 86 to 90 degree environment with plenty of humidity. We decided that an immersion circulator mounted on a large bus tub heated to 95 degrees was an efficient way to meet both criteria. If I wrapped the whole setup to create a mostly closed environment, the ambient temperature above the water level was 88 degrees, and the abundance of water ensured plenty of humidity. I was flying blind here, since most modern setups for incubation were pretty janky themselves: Beer coolers, fridges, dehydrators, heating pads, and temperature regulators were all fair game. We wanted to test recipes using a setup that any home cook could rig, so we didn’t go for a muro—the hyper-traditional high-temperature, high-humidity incubation chamber that required hours of TLC.

Some of my coworkers gave me funny looks when I pulled something out of incubation—incredulous at the sight of me examining, cooking, and then gingerly nibbling at a piece of moldy pork. Who in their right mind would eat a box of moldy potatoes or—worse—some rotten looking steaks? But Jeremy kept reassuring me that as long as the koji grew, the food would be good.

And grow it did. After a ton of trial and error, rancidity, and spoilage, I ended up with fuzzy rice, fuzzy meats, and fuzzy vegetables. Some of it was great: The rice was very close to the store-bought granular koji I had been working with, and the vegetables seemed promising. The meats were hit or miss: beef and pork seemed to work, but fish was a no go. Here and there I ran into problems with spoilage, but a quick cure in salt and sugar before inoculating seemed to curb that problem. As of the writing of this article, I’m still working the kinks out for incubation. I don’t yet have a consistent product or process that I am happy with, but as I go along I’m sure I’ll have something amazing—and edible—in the near future. Stay tuned.

Do you use koji at home? We’d love to hear about what you’re doing, eating, and experimenting on. Drop us a note in the comments below.

Field Photography by Kevin White.

Test Kitchen Photography by Steve Klise.

Food Styling by Elle Simone.