What is Koji

"Koji" stands as a cornerstone in Japanese cuisine, essential for producing sake, soy sauce, miso, and more. 

This culinary alchemy begins with cooked rice inoculated with Aspergillus oryzae*, a mold that infuses the ingredient with unique qualities. Koji, a precursor ingredient in Japanese cuisine, releases key enzymes—Amylase and Protease—during fermentation. 

Amylase transforms starch into natural sweetness, while Protease decomposes proteins into amino acids. This transformative process gives rise to Japanese culinary treasures like Amazake and miso.

Aspergillus orysae is a microscopic fungus cultured in a controlled environment. The fungus produces spores, a powder named tane koji. Different strains of tane koji are cultured, allowing for specific applications: sake, miso, shoyu, etc. It is used to inoculate steamed rice (or other grains). Incubated for two days in an environment where warmth and humidity are controlled and perfectly balanced, the grain is transformed into koji. This is where the magic begins.

Functional Ingredient

Its transformative powers and how it infuses food with unique qualities is what makes koji such a magical ingredient.
When used in cooking or marinating, the Koji enzyme enhances flavors and tenderizes proteins, making it a versatile addition to a variety of dishes. 

Anchored firmly in the Japanese culinary tradition, koji is the wondrous ingredient that made possible such magnificent products as sake, amazake, miso and shoyu and many others. Yet, the wonderful thing about koji is that it lends itself perfectly well to creative explorations and innovation in culinary fermentation technology.

 The main enzymes at work here are the amylase and the protease enzymes. 
 The amylase enzyme breaks down starches into simple sugars, thus the sweet taste. Amazake, a sweet non-alcoholic beverage, is a good example of this. Mixed with specific yeasts it can also turn into alcohol, sake. 
 The protease enzyme breaks down proteins into amino acids. Legumes, meat, fish are transformed to bring out the umami flavor. Miso, shoyu (soya sauce), cured meat, garum (fish sauce), these are products associated with umami**.

**Umami is one of the five flavors (along with, sweet, salty, sour and bitter). It has been translated as delicious, savory, unctuous, rich, deeply satisfying.

Koji & Innovation

In recent years, there has been a great surge of interest for koji. Sandor Katz, the godfather of fermentation, NOMA, the famous Copenhagen restaurant renowned for spearheading culinary innovations, Jeremy Umansky and Rich Shih with their book Koji Alchemy, Kirsten and Christopher Shockey with their books and workshops on koji, have all contributed to widening the interest for koji. Chefs worldwide are adopting koji, experimenting with it as they transform locally grown ingredients.

One example of this is garum, which is traditionally a fermented fish sauce that has been used for thousands of years in Eastern cuisine. The people at NOMA have chosen to explore a revolutionary approach to garum fermentation. Applying the unique qualities of koji to the process, they created a milder version of the fish sauce, creating a new product. They also made garum with meat, insects, pollen, rose and shrimps, etc. NOMA’s innovative use of koji has influenced chefs and food enthusiasts worldwide. They have opened the door to the endless possibilities offered by this most versatile ingredient, koji.