Written and illustrated by Misa Ono
Soy sauce is written with the kanji “醤油.” “醬”by itself is pronounced Hishio, which means “sauce for fermented foods with salt.”
There are two theories how Japanese people started to use soy sauce. In the Yayoi era, there were sauces for fermented meats, fish, grasses (vegetables) and grains with salt. The one for grain was called “Koku-bishio.” It was originally brought from China, and it is said that soy sauce was originated from this koku-bishio. The other theory is that soy sauce originated from the liquid floating on the top of a barrel of miso. The ingredients of soy sauce are soy beans, wheat, salt, and koji. The ingredients of miso are soy beans, rice (sometimes barley depending on the production region), salt, and koji. Both of them are produced from grains, and the ingredients are very similar. Both theories seem right to me.
Soy sauce that you can generally find at supermarkets is “Koikuchi-shoyu” which means dark soy sauce. This is the process for producing soy sauce: Mix steamed soybeans (sometimes low-fat soybeans) and crushed, roasted wheat. Breed koji mold in a mixture of soybeans and wheat, and produce soy sauce koji. Then, add salt water into soy sauce koji, ferment and ripen it. Filtrate the liquid and stop the fermentation with heat. The koji enzyme turns the protein of soy beans into an amino acid, which is umami, and also turns the oil content of soybeans to glycerin and fatty acid. That’s how the flavor of soy sauce becomes rich and tasty.
It usually takes 6 months to one year to ferment and ripen soy sauce. It is a very long time. Therefore, it is difficult to open a soy sauce shop instantly and most shops are usually many years old. Although it takes time, as sauce is aged, its flavor and smell seem to get richer, and it tastes better. Then, due to the reaction of sugar and amino acid, the color turns deeper and darker.
In the Edo era, people started to eat raw fish in the ocean-surrounded country, Japan. For the reason that soy sauce reduces the fishy smell of raw fish, soy sauce became loved by Japanese people, and the basis for the traditional Japanese food culture of soy sauce was formed, such as sushi, soba, tempura, ell kabayaki (a preparation of fish being split down the back, boned and dipped in a sweet soy sauce-base sauce before being broiled), and yakitori. It cannot be helped, but most of foreigners say that most of Japanese foods taste like soy. However, we are very happy when people from outside Japan understand how good soy sauce is!