Historical Background 

Koji is thought to have been used for more than 2000 years. Some say it was introduced at the same time as rice farming during the Yayoi period, others say it stems from when sake was made with koji in the Kofun period.

Characteristics of Koji in Akita

In a process specific to Yokote city Akita, residents use as much as two to three times the typical amount of kōji when making miso. This increased ratio helps the soybeans ferment faster, so the miso is ready for consumption after being stored for only a year.

Fermenting grains, vegetables, and other foods began out of necessity. Although the people of Yokote were surrounded by fertile soil and clean natural water, agriculture was all but impossible during the winter months. To survive the long winters, residents developed and shared preservation techniques that were passed down through the generations to create a distinctive food culture. The people of Yokote also came to use kōji as a seasoning or as a sweetener rather than simply for preservation. However, in the decades following World War II, Japan’s food culture began to shift away from food prepared according to traditional methods, focusing instead on industrially processed foods. As a result, much generational knowledge about food preservation has been lost.

However, in recent years, younger residents have been rediscovering traditional food practices and attempting to revive the knowledge possessed by the prewar generations for the sake of generations to come. The municipal government supports revival efforts throughout the region, and some local restaurants have begun holding cooking classes and other community events to share information on fermentation techniques. Initiatives like this help to ensure that current and future generations will be able to carry on the techniques of Yokote’s kōji-based food culture.

In addition, Koji is an important ingredient when making Japanese sake. In the nineteenth century, brewers began to add a type of fungus called kōji to steamed rice to cause fermentation. This is one of several aspects that creates variety in the finished taste.’ There are two Sake breweries in Akita: Yamamoto Brewery and Kikusui Brewery. Kikusui Brewery says ‘The brewers work on Kikusui’s saké with a well-known ad-age in mind: Ichi kôji, ni moto, san tsukuri (“Kôji is of first importance, shubo is of second importance, and moromi is of third importance.”). This means making good kôji (rice mold) is the most important element in brewing good saké.