Soy Sauce (Shoyu)

Soy sauce is a Japanese traditional condiment. It has been used for various Japanese foods such as Sashimi, Sushi and Udon noodle soups. Soy sauce products produced in the Kyushu area tend to be sweeter than those in other regions in Japan.

The Ingredients of Soy Sauce

The main ingredients of soy sauce are soybeans, wheat and salt.

Soybeans (defatted)


Salt Storage Room

Storage silos for soybeans and wheat

Soy Sauce Manufacturing Process

(1) Cooking Ingredients
Soybeans are steamed. Wheat is roasted and crushed. They are mixed and used for koji (malt) making. Salt is dissolved in water.

Continuous soybean cooking machine

Wheat roasting machine

(2) Making Koji
Koji mold (Aspergillus oryzae or Aspergillus sojae) is added to the mixed soybeans and wheat, and then incubated for three days to make koji. The word “koji” means soybeans and wheat with their surface covered with koji mold. It contains various enzymes that greatly contribute to the following moromi fermentation and maturation process.

Koji making machine

(3) Making Moromi
Koji is mixed with salt water. This mixture is called “Moromi”.
Moromi is then transferred to a fermentation tank.

Soy sauce fermentation tanks

(4) Fermentation and Maturation
Moromi is slowly fermented and matured for a period of six months. Koji enzymes, yeast and lactic acid bacteria act in this process and create various tastes and flavors.

Soy sauce moromi during fermentation
(5) Filtration
After fermentation and maturation, moromi is wrapped one by one with cloths and they are stacked into many layers. Then they are slowly compressed and the moromi is filtered through the cloths. In this way, raw soy sauce liquid called “Kiage” is obtained from the moromi.

Preparation for soy sauce filtration

Filtration of soy sauce moromi
(6) Heat treatment and Refining
Raw soy sauce is heat-treated for sterilization and then refined. The color, aroma and flavor of soy sauce are further enhanced during this process.


(7) Inspection and Bottling
After the inspection, soy sauce is filled into glass or plastic bottles.

Soy Sauce bottling machine

Finished soy sauce

Soy Sauce Making Process