What is traditional soy sauce making?
In the past, soy sauce, along with miso, was made in each community.
At the very least, every village had its own soy sauce shop, and soy sauce continued to be made as part of daily life.
The ingredients in traditional soy sauce consist of only wheat, soybeans, and salt. After the wheat has been roasted and soybeans steamed, they are sprinkled with kōji mold and left to ferment for about three days while maintaining a constant temperature and humidity to produce shōyu kōji (soy sauce malt) that is completely covered with kōji mold. The soy sauce malt is then mixed with salt water to make moromi, which undergoes fermentation and aging in barrels for one to two years.
When the aged moromi is pressed, it produces a soy sauce with a rich aroma and deep flavor.
The Changing World of Soy Sauce
Soy sauce has always been the most important seasoning in Japanese cuisine.
However, due to food control measures and other factors during World War II, it became difficult to make soy sauce, which requires a lot of time and effort, because the raw materials could not be secured.
As a result, one of the biggest changes after the war was in the way soy sauce was made.
Instead of the traditional honjōzō method using whole soybeans, which required years of slow fermentation on a small scale, the majority of soy sauce is now made from "defatted" soybeans, which are fermented in large quantities in a short time, and to which synthetic amino acids are added.
Domestic sea salt
Domestically grown soybeans
We use soybeans grown by our staff, as well as other domestically grown soybeans.
Domestically grown wheat
We purchase wheat from local, certified organic farmers.
Making Imashibori Shōyu
First, locally grown wheat is slowly and carefully roasted (the wheat comes from certified organic farmers).
Once the wheat begins to crackle and split open, it is cooked a little more until it turns a golden brown color, without charing it.
When it floats in a glass of water, it is ready.
The roasted wheat is then ground into 6~7 pieces using a grinder (or sometimes a millstone). Unevenly sized pieces are considered good for making soy sauce.
The soybeans, which include those grown by Imashibori staff as well as other domestically grown soybeans, are washed thoroughly, soaked in water overnight, and boiled until tender (soft enough that they can be crushed between the thumb and pinky finger, or about as soft as an earlobe).
The ground wheat and boiled soybeans are then cooled until they are cool to the touch, sprinkled evenly with kōji mold, and placed in the kōjimuro (a room for producting kōji). If the temperature is too high, the kōji mold will die.
The mixture is left to ferment for 72 hours while maintaining sufficient humidity and keeping the temperature around 30 degrees Celsius. Because of this, shōyu kōji (soy sauce malt) is also referred to as three day kōji.
About 24 hours after irekōji (the step where the soy sauce malt is placed in the kōjimuro), the kōji mold becomes active and begins to multiply, generating heat.
The resulting clumps of soy sauce malt are broken down into small pieces in a process called teire, and oxygen is supplied to lower the temperature.
After 72 hours, when the soy sauce malt is removed from the kōjimuro (a step known as dekōji), it is completely covered in green kōji mold.
If the temperature is too high, it will produce Bacillus subtilis natto (the bacteria used to make nattō), so great care is taken to control the temperature even during the night.
We put all of our effort into making good shōyu kōji (soy sauce malt), because it is what gives soy sauce its deep flavor.
The Role of Kōji Mold
The green, fuzzy growth in the picture below is kōji mold (Aspergillus oryzae), a type of fungus which is normally found in the ears of rice.
In order for kōji mold to reproduce, it needs the energy created when enzymes break down soybeans and wheat. Therefore, it produces many enzymes itself to continue its rapid proliferation.
These enzymes break down soy and wheat proteins into peptides (a chain of amino acids) and amino acids (a source of umami), wheat starch into glucose (sweetness), and soybean oil into glycerin (umami).
In addition, kōji mold produces many nutrients necessary for complex biological activities, such as B vitamins, pantothenic acid, nicotinic acid, niacin, and inositol.
The products of this kōji mold are the source of the basic umami, sweetness, and color of soy sauce.
Salt and water are added to shōyu kōji (soy sauce malt) to make moromi (a softly solidified mixture that undergoes fermentation and is then pressed to make soy sauce). The moromi continues to ferment in barrels, where lactic acid bacteria convert some of the sugar into organic acid through lactic acid fermentation, which gives the soy sauce its depth of flavor and enhances its aroma.
In addition, yeast bacteria play an active role, continuing the yeast fermentation process that produces as many as 300 flavor components, further contributing to the flavor and aroma of the soy sauce.
Incidentally, many of the gastrointestinal medicines on the market are made using kōji mold. It is also used in detergents that are marketed as enzymatic.
Isn't kōji mold amazing?
Making Imashibori Shōyu (Cont.)
Finally, it is time to brew the soy sauce.
Coarse salt (Coarse salt is used because refined salt has fewer minerals) is dissolved thoroughly in water.
The shōyu kōji (soy sauce malt), now fuzzy with kōji mold, is added to the barrel and stirred thoroughly to ensure an even salt concentration.
The salt will accumulate at the bottom of the barrel, so after brewing, the soy sauce is occasionally stirred (a process known as kaiire) until the salt is dissolved. It is then transferred to another barrel (tenchigaeshi) to ensure an even salt concentration once more.
After a month or two, the fermentation becomes mainly lactic acid fermentation, which requires less oxygen, so it is not stirred as much.
Before summer, it becomes mainly yeast fermentation, this time with regular mixing and aeration. The heat of summer promotes sufficient fermentation, further darkens the color of the soy sauce, and finally creates a nice aroma.
At this time, kaiire is performed only once a month to prevent flavor components from escaping.
In this way, the soy sauce prepared in winter grows into delicious soy sauce over the summer, thanks to the power of microorganisms and everyone's loving care.
At Imashibori, we pursue even greater flavor, and age our soy sauce for two years before turning it into products.
Imashibori Shōyu (Moromi), Soy Sauce for Eating, and Ikiteru Shōyu (Extra Virgin Soy Sauce) are all made from soy sauce that has been aged for two years.