Production method (Soy Sauce)
Let’s learn about the production method (Soy Sauce).
There are mainly 5 types of Soy sauce (Shōyu) in Japan (Please refer to the page of Soy sauce )a) Koi-kuchi
b) Usu-kuchi
c) Tamari
d) Sai-shikomi
e) Shiro (white)The best way to understand the difference among these types is to understand the production method (Soy Sauce).
Surely it will make a fruitful trip.
a) Koi-kuchi
Koi-kuchi is the most popular Soy sauce (Shōyu) in Japan.
Roughly speaking, the production method of Koi-kuchi is as mentioned below:
1) mix cooked soybeans and broken wheat (the amount of these two is the same)
2) add Koji-bacteria to make Koji
3) add salt water and make it ferment
4) after fermented enough, extract the juice from 3).
This juice is what we call ‘Nama–Shōyu‘ (raw Soy sauce)*.
5) heat 4) for sterilization, color adjustment, obtaining aroma etc.
<*Note>
– Recently, Nama–Shōyu has become itself a selling product.
– Moreover, Nama–Shōyu plays an important role in the production of Sai-shikomi.

b) Usu-kuchi
As you can see the Koi-kuchi has a dark color and the chefs who placed great value on the appearance of their cuisine didn’t like the which can spoil their precious works.
Hence, they sought lighter colors in soy sauce and their desire made the Usu-kuchi born.
Always, necessity is the mother of invention.
The production method of Usu-kuchi is almost the same as above Koi-kuchi.
But the fermentation period is shorter to avoid gaining dark color.
For this reason, it requires more salt than Koi-kuchi to finish the fermentation during limited period.
Frequently, sweet-sake (Mirin)* or syrup is added at the end of this process to cover strong saltness.
<Note>
I know it’s quite confusing, but this sweet- sake (Mirin) is different from Ama-sake which I introduced as a nutritious drink.
Mirin is transparent as Sake and we use it mainly as a seasoning.

c) Tamari
Tamari literally means accumulate.
As I mentioned in the page of Soy sauce, the origin of Soy sauce (Shōyu) was the juice accumulated in a Miso barrel.
(Although I’m not sure this story is 100% correct).
Basically, the production method of Tamari is almost the same as this primitive Soy sauce.
Following its origin, Tamari doesn’t require wheat (only soybeans).
But recently some wheat (usually about 10% of the total amount) is often added to gain a flavor.
d) Sai-shikomi
Amai is Umai.
In the past, people were always seeking something sweet.
To get a sweeter soy sauce, a new production method called Sai-shikomi was born in Yanai (Yamaguchi prefecture) at the end of the 17th century.
In the production of Sai-shikomi, Nama- Shōyu (raw Soy sauce) is indispensable.
As I mentioned in the part of a) Koi-kuchi, Nama- Shōyu is the juice gained in the production process of Koi-kuchi.
Hence, it is already fermented.
By using the Nama- Shōyu as an ingredient, fermentation repeats itself almost twice.
That is why we call this Soy sauce “Sai-shikomi” which literally means “repeated fermentation”.
e) Shiro (white)
As I mentioned in the part of b)Usu-kuchi, some chefs didn’t like the dark color of Koi-kuchi.
They sought for more and more light color in soy sauce.
At the beginning of the 19th century, the Shōyu whiter than Usu-kuchi was born in Hekinan (Aichi prefecture).
This soy sauce is called “Shiro-Shōyu” which means white Shōyu.
Different from other types of Soy sauce, the main ingredient of Shiro (white) is wheat.
Only a small portion of broken soybeans are added. Because some nutritional elements contained in soybeans can cause the dark color which is represented by Koi-kuchi.
By using less soybeans, the finished soy sauce becomes whiter.
As well as Usu-kuchi, the fermentation period is shorter than others.