What is Koji

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Koji: The Heart of Japanese Fermentation

Koji is a cornerstone of Japanese cuisine, integral to the production of sake, soy sauce, miso, and many other traditional foods. This remarkable ingredient, often referred to as "Japan's fermentation magic," is essential for unlocking the deep umami and rich flavors characteristic of Japanese dishes.

The Koji Process: Unlocking Flavor

The journey of koji begins with steamed rice that is inoculated with Aspergillus oryzae, a beneficial fungus that transforms the rice with unique properties. As a precursor in fermentation, koji releases powerful enzymes—Amylase and Protease—which play crucial roles in the fermentation process.

  • Amylase breaks down starches into natural sugars, contributing to a subtle sweetness.
  • Protease decomposes proteins into amino acids, which are key to developing the savory umami flavor.

Through this delicate and transformative process, koji creates the foundation for beloved Japanese products such as Amazake and Miso.


Cultivation of Aspergillus Oryzae: The Magic Behind Koji

Aspergillus oryzae is a microscopic fungus that is carefully cultivated in a controlled environment. This fungus produces spores, which are then ground into a powder known as tane koji (seed koji). Various strains of tane koji are cultured for specific applications, such as making sake, miso, or shoyu (soy sauce).

The spores are inoculated into steamed rice (or other grains), which is then incubated in a carefully controlled environment where both temperature and humidity are finely balanced. After about two days, the rice is fully transformed into koji—ready to be used in crafting the signature flavors of Japanese cuisine. This is where the fermentation magic begins!

Functional Ingredient


THE MAGIC OF KOJI
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.

HOW IT WORKS
 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.
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Koji & Innovation

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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.

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