Summer Vacation Trip: Soy Sauce Exploration, Part 1
- Junna.K
- Sep 29
- 6 min read
Updated: Oct 2
Konnichiwa! I'm Junna, a sushi instructor!
I took a long break from lessons until September 23rd, but during that time I visited various places around the country and learned a lot about soy sauce, an essential ingredient for sushi.
This time, I will introduce the soy sauce brewery in two parts.
Before we get started, let me explain what soy sauce is made of.
The basic ingredients of soy sauce are soybeans, wheat, and salt water. By adding koji mold to these ingredients and allowing them to ferment and mature, the unique flavor, aroma, and color of soy sauce are created.
[Making process of Soy sauce]
1-Raw material processing
The soybeans are steamed.(Photo left)
The wheat is roasted.(Photo right)
Raw materials are often processed using machinery like the one shown in the photo.
2-Making koji
Steamed soybeans and roasted wheat are added to koji starter and allowed to grow.
It produces enzymes that break down soy protein and wheat starch into amino acids and glucose.
3-Add brine
Next, brine is added to create the “Moromi”(mush).
This stops the koji mold from multiplying and the enzymes it produces begin to work.
4-Preparation → Fermentation and aging
When placed in a tank or barrel and left to ferment and age for a long period of time, it changes color to the color of soy sauce.
5-Compression
The mash is pressed and separated into raw soy sauce and soy sauce lees.
6-Pasteurization and filling
The process of heating raw soy sauce is called "pasteurization." It adjusts the color, taste, and aroma of the soy sauce and also sterilizes any microorganisms remaining in the soy sauce.
Finally, bottle it and it's done.
I hope you now understand the basics of how it's made. Each soy sauce brewery has its own unique method, and there are various methods for making koji, but the basic process is as mentioned above.
The common thread among the soy sauce breweries I visited this time was that they were all brewed in wooden barrels. In fact, it is said that the amount of soy sauce brewed in wooden barrels in circulation in Japan is only about 1%.
The use of wooden barrel-brewed soy sauce, which was once the norm, has steadily declined, and now brewing in tanks, which allows for mass production in a short period of time, has become mainstream.
However, there are various reasons why brewers continue to use wooden barrels for brewing. The first is that the bacteria living in the wooden barrels are unique to each brewery. While they do not produce a uniform taste, they make it possible to bring out the umami and aroma of soy sauce at levels exceeding 100—even 150 or 200.
Place to visit: 1. Kaneiwa Shoyu, Wakayama Pref.
Founded in 1912, this soy sauce maker is located in Aridagawa Town, Wakayama Pref., right along the Aridagawa River, which is fed by water from the Mt. Koya mountain range.
This town, next to Yuasa Town in Wakayama Pref., the birthplace of soy sauce, has been carrying on the traditional soy sauce culture.
This area was once located on the Sanmon Road, a route taken by people on their way to worship at Mount Koya, and flourished as a post town. It is said that Kobo Taishi, also known as Kukai, visited this area at one time and called the spring water here "the sacred water of eternal youth and longevity." For this reason, the purity of the water has been revered since ancient times.
The water of this river originates from the water veins of Mt. Koya, and in Yuasa, the birthplace of soy sauce, the brewing culture of sake and soy sauce developed especially along this river. Apparently, there were once three soy sauce makers in this area. Although the water's components have never been scientifically studied, the local feeling and tradition that "this river's water is good" means that just as each brewery's barrels have their own unique characteristics, the water itself is treasured as something that creates the individuality of each brewery.
The founder decided to seriously pursue soy sauce production after receiving requests from people around this town, and established a brewery just a stone's throw away from where he currently works. After studying at Yuasa Soy Sauce, he founded the current Kaneiwa Shoyu.
This time, we were given a tour of the brewery by Shohei Iwamoto, the fifth generation owner.
After graduating from university, he thought he would have to study at a major soy sauce brewery, and thought he would have to study at an agricultural university or major in science to get in. Having studied humanities, he thought he wouldn't be hired by a major soy sauce manufacturer, so he started making koji(malt) at a sake brewery, where he felt welcomed and appreciated. After getting married and having children, he realized the limitations and difficulties of supporting a family as a salaryman. He also felt that being an employee meant making koji and brewing in a set way, which prevented him from doing things his own way or taking on new challenges. So, in 2021, he decided to work at his family's soy sauce brewery. Now, he spends his days trying new things to make delicious soy sauce, and although he isn't always successful, he says he finds it very enjoyable to be able to brew the way he wants.
[Raw materials]
・Whole Soybeans(from Hokkaido), cracked soybeans
・Wheat(from Ohmi)
・Brine
[Characteristic method]
Koji making:
It is made in a rare koji room called the “NARA-KOSHIKI(Nara traditional style)”.Mesh boards are laid out on the floor, and the soybeans and wheat sent by air are laid out on top of them, and koji mold is then applied to them. The large screw-like thing at the back is used to stir the mixture, and it moves back and forth. According to him, it only moves a little, so in the end they mix it by hand as well.In this room can brew one wooden barrel's worth of sake.Apparently, it is essential to adjust the temperature to create the right enzymes for the soy sauce by ensuring good ventilation and mixing. The fourth-generation owner often says, "The koji may sleep, but the brewers never sleep," and this comes from the fact that he and his father take turns watching over the brewery day and night, as the equipment is neither old nor new and is mechanical and involves a lot of manual work.
[Soy sauce stored in a wooden barrel]
There are a total of 23 wooden barrels, and after adding the koji and brine, it’s aged for two years.Once the aging period is over and the soy sauce is bottled, it is complete.
Pasteurized Koikuchi(General Japanese) soy sauce is called "Koshiki Shoyu"Unpasteurized raw soy sauce is called "Kokubishio"Soy sauce that has been pasteurized and sweetened with mirin or other ingredients is called "Tennen Jozo (naturally brewed) Shoyu".
Place to visit: 2. Ishimago Honten, Akita Pref.
Ishimagoto Honten is a miso and soy sauce brewery founded in 1855. The town of Iwasaki in Yuzawa City, Akita Pref., where the brewery is located, is famous for Iwasaki Hachiman Shrine, where Minamoto no Yoshiie donated stirrups to pray for victory in battle during the Heian period, and the legend of Princess Noe, one of Akita's three great legends.
The production method has remained almost unchanged in the 170 years since the company was founded, and the seasonings are made using a method that is committed to handmade production with little use of machinery. Part of the brewery has been registered as a National Registered Cultural Property, as it shows the transition in architectural styles from the Meiji to Taisho eras. The brewery has a built-in library structure, and as the area is prone to heavy snowfall, it is an indoor brewery, with the exposed red bricks at the bottom remaining as they were at the time. We can feel the historic brewery with all five senses: eyes, ears, and taste etc… …
Representative products include "Hyakuj”, “Shoju” a soy sauce made entirely in wooden barrels, and "Ishimago Miso," a miso paste.
We spoke with Kana Ishikawa, the seventh generation owner of the brewery, who is involved in everything from making miso and soy sauce to promoting the brewery at events such as the Kioke Summit. She gave us a tour of the brewery.
She started helping out at the brewery around the time she graduated from university, but at the time she was also working in a different field.She is now the executive director and the seventh generation head of the family, producing miso and soy sauce.
[Raw materials]
・Soybeans from Akita
・Wheat from Akita
・Brine
[Characteristic method]
Roasting wheat over coal:Most soy sauce makers use a burner or sand to heat the barley, but here they roast it using coal, it’is the only method still in use in Japan.They use a brick-built barley roaster (a cutting-edge model introduced during the Meiji to Taisho periods) and create a fragrant aroma that can only be achieved by using coal fired power imported from Hokkaido, without using a burner. Apparently, the barley is turned over and over while being visually checked for color, which tests the skill of the craftsman.
[Soy sauce stored in a wooden barrel]
The koji is brewed in wooden barrels made from Akita cedar. The koji is carried over and over again until each 5t barrel is filled.Once the preparation is complete, the mash is left to mature for about a year and a half, producing a rich soy sauce.
continue to Part 2... ...
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