Soy sauce is one of the most essential elements of Japanese cuisine—but for many visitors, it remains surprisingly misunderstood.
In Japan, soy sauce is known as shoyu, a traditional fermented seasoning that has shaped the country’s taste for centuries.
What Is Soy Sauce (Shoyu)?
Soy sauce, or shoyu, is a fermented liquid made from:
- Soybeans
- Wheat
- Salt
- Water
Through a long and natural fermentation process, these simple ingredients transform into a deeply complex seasoning rich in umami.
However, in Japan, 80% of the soy sauce distributed through outlets such as supermarkets is made using defatted soybeans. Defatted soybeans are a raw material created by extracting and removing oil from soybeans beforehand and adjusting the protein content and particle size for soy sauce brewing. Because the oil has been removed, the resulting soy sauce is characterized by a clean, crisp finish combined with a rich, deep umami flavor.
Shoyu brewed using traditional methods at soy sauce breweries is made from whole soybeans—which retain their natural oil content—resulting in a mellow aroma, a gentle sweetness, and a deep, rich flavor.
The Fermentation Process Behind Shoyu
Traditional shoyu is made through a slow, natural process that can take months or even years.
Step 1: Koji (麹)
A mold culture is cultivated on soybeans and wheat.
Step 2: Moromi Mash
The mixture is combined with saltwater and begins fermentation.
Step 3: Aging & Pressing
The mash is aged over time, then pressed to produce soy sauce.
This process creates:
- Amino acids (umami)
- Aromatic complexity
- Deep, layered flavors
Why Does Shoyu Taste So Complex?
Unlike simple salty seasonings, shoyu contains natural glutamates created during fermentation.
This results in:
- Depth rather than intensity
- Balance rather than sharpness
In Japanese cuisine, shoyu enhances ingredients instead of overpowering them.
Related post:
Types of Shoyu
In Japan, different styles of shoyu reflect regional food cultures:
- Koikuchi (dark soy sauce) – the most common
- Usukuchi (light soy sauce) – often used in Kansai cuisine
- Tamari – richer and thicker
- Shiro (white soy sauce) – unique savory aroma and subtle sweetness
Each type offers a different expression of fermentation.
Shoyu and Japanese Culture
Shoyu is more than just soy sauce—it represents:
- The importance of fermentation
- The concept of umami
- A philosophy of harmony in cooking
It is deeply embedded in everyday Japanese life.
Related post:
How Shoyu Shaped the Japanese Sense of Taste
Where to Experience Real Shoyu
While soy sauce is used across Japan, such as Choshi and Noda in Chiba, Tatsuno in Hyogo, Shodo Island in Kagawa, there is one place where its story truly begins:
👉 Yuasa in Wakayama
This small coastal town is considered the birthplace of Japanese shoyu, where traditional brewing methods are still preserved today.
👉 Continue reading:
Yuasa Soy Sauce: The Birthplace of Japanese Shoyu
Yuasa Shoyu Soy Sauce & Fermentation Journey
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