Koikuchi Shoyu vs Usukuchi Shoyu: Japanese Soy Sauce

Respectively known as “dark soy sauce” and “light soy sauce” in English speaking countries, “Koikuchi Shoyu (濃口醤油)” and “Usukuchi Shoyu (薄口醤油)” are the most common and basic types of soy sauce which can be found in any supermarket in Japan.

Koikuchi Shoyu (Dark Soy Sauce) vs Usukuchi Shoyu (Light Soy Sauce)

Shoyu Japanese Soy Sauce

But do you know how Koikuchi Shoyu or dark soy sauce differs from Usukuchi Shoyu or light soy sauce? For people who don’t know much, this article will explain the difference.

Salt Concentration

You might think Usukuchi Shoyu has a lower salt concentration than Koikuchi Shoyu as the former soy sauce has a lighter color than the latter, but the truth is the other way around.

Usukuchi ShoyuUsukuchi Shoyu or Light Soy Sauce

While the salt concentration of Japanese dark soy sauce is 16 to 17 percent, that of Japanese light soy sauce is 18 to 19 percent.

The “light” in the light soy sauce actually comes from its color, not taste. In the production process, Usukuchi Shoyu uses more salt, has a shorter fermentation time, making its color lighter than Koikuchi Shoyu. 


Koikuchi ShoyuKoikuchi Shoyu or Dark Soy Sauce

As Koikuchi Shoyu, or Japanese dark soy sauce, has a longer fermentation process, it is more aromatic than the light soy sauce Usukuchi Shoyu and packed with flavor. 

Koikuchi Shoyu is the most basic soy sauce in Japan, and if the recipe calls for “Shoyu”, this soy sauce is generally used.


Kyo Ryori

Koikuchi Shoyu gives more “soy sauce” taste and aroma to the dish, and it is most widely used in Japanese cuisine.

Meanwhile, Usukuchi Shoyu can accentuate the original taste and color of food materials, and it is commonly used in the local cuisine of Kyoto “Kyo-Ryori (京料理)”.

(Reference Pages: Kawanaka Shoyu, Meiman, Ajinomoto )


Hi, I'm Tomo, a Japanese blogger living in Niigata Prefecture, Japan. For the purpose of enriching your life, I would like to introduce things about Japan on this blog, especially unique Japanese products, cooking recipes, cultures, and facts and trivia.

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