ABOUT KOJI
A GENTLE GUIDE TO FERMENTATION
日本の食文化を育んできた微生物
A Microbe That Shaped Japanese Food
Koji begins with the quiet work of a tiny mold on rice, barley, or soybeans.
Discover how it brings sweetness, umami, and gentle depth to everyday food.
WHAT IS KOJI
麹とは
What Is Koji?
Koji is rice, barley, soybeans, or other grains cultivated with Aspergillus oryzae. It appears as a soft white bloom over the grains, while a diverse set of enzymes works quietly within.
Starches become natural sweetness; proteins become layered umami. Aroma and texture open up, too. From miso, soy sauce, sake, and amazake to ordinary home cooking, koji is a quiet beginning for Japanese fermentation.
TYPES OF KOJI
麹の種類
Types of Koji
The ingredient shapes the aroma, character, and flavor it brings.
Rice Koji
The most familiar koji, gently drawing out natural sweetness.
Amazake · Shio Koji · Miso · Sake
Barley Koji
Bringing the nutty warmth and gentle depth of barley.
Barley Miso · Shochu · Soy Sauce
Soybean Koji
Turning protein into deep umami and lasting richness.
Bean Miso · Hatcho Miso · Soy SauceTHE TASTE OF ENZYMES
酵素が引き出すおいしさ
Enzymes That Unlock Flavor
Amylase
The natural sweetness of amazake.
Protease
Tenderness in meat and fish.
Lipase
Depth in fermented foods.
As koji grows, it produces enzymes that break food into forms the palate can recognize. They do not add flavor so much as reveal the flavor that is already there.
THE MAKING OF KOJI
麹づくりの四つの工程
Four Steps to Raising Koji
Making koji means attending to warmth, humidity, and aroma—giving the grain and the mold precisely the time they need.
01
Steam
Rice, barley, or beans are hydrated and steamed until tender.
02
Inoculate
Koji spores are evenly scattered across the cooled grains.
03
Cultivate
Warmth and humidity are watched as fine mycelium slowly spreads.
04
Finish
A sweet aroma and white bloom signal that the koji is ready.
KOJI IS NOT A RULE. IT IS A SMALL DAILY CHOICE.
DAILY KOJI
毎日の食卓に、麹を
A Gentle Koji Habit for Every Day
Use shio koji in place of salt.
Season meat, fish, or vegetables with it to gently reveal their own flavor.
Use amazake in place of sugar.
Rice-koji amazake offers a natural sweetness without refined sugar.
Make miso soup a small ritual.
Let miso—born from koji, soybeans, and salt—ground the everyday table.
Koji is a food ingredient and is not intended to treat or prevent disease.