Liquid Culture Koji (Aspergillus oryzae)

🌾 What is Koji?

Koji is a fermented grain product (usually rice, barley or soybeans) inoculated with the fungus Aspergillus oryzae. This fungus produces enzymes that break down starch, proteins and fats into sugars, amino acids and fatty acids - the building blocks of flavor.

Koji is the basis of many Japanese flavorings such as:

• Miso
• Soy sauce
• Sake
• Mirin
• Amazake

🧫 Growing your own Koji: from culture to fermentation
 

1. Supplies

• Koji kin (the spores of Aspergillus oryzae)
• Rice or other starchy substrate
• Steamer
• Fermentation cabinet or improvised warm room (30-32 °C)
• Clean container and damp cloth

2. Roadmap

1. Soak and steam Soak the rice for 6-12 hours, then steam it until cooked but firm.
2. Cooling and grafting Let the rice cool to ±30 °C and mix in the koji kin.
3. Fermentation (48 hours) Allow the mixture to ferment at 30-32 °C. Scoop it every 12 hours for even growth.
4. Done! After 48 hours, the rice is covered with a white down layer and smells sweet and nutty. This is fresh koji.

You can use it right away or dry/freeze it for later

🍜 Traditional uses

🍽️ Modern Applications

Koji is a culinary superstar in Western cuisine today:

• Shio Koji: marinade of koji, salt and water - makes meat more tender and vegetables more flavorful
• Koji butter: umami-rich butter for on bread or in sauces
• Koji caramel or ice cream: surprising applications in desserts
• Vegan cheeses: fermenting nuts or grains with koji for deep flavor.

Even top chefs like at Noma in Copenhagen use koji as a flavor enhancer in innovative dishes.

📚 Recommendations for deepening

• Koji Alchemy - Jeremy Umansky & Rich Shih
• The Noma Guide to Fermentation - René Redzepi & David Zilber

Koji is not just any mold - it is an ancient flavoring that bridges the gap between tradition and innovation.