Many different things all over the world are share the name “sushi”. However, when Japanese people hear this word they think of “nigiri sushi”. Of course outside of Japan, it probably more commonly refers to sushi rolls.
Similarly, the way soy sauce is used also differs greatly between people in Japan and those in other countries. The soy sauce used for nigiri sushi is not primarily intended to add saltiness. Rather, it serves to suppress the fishy odor of raw fish and to enhance umami by adding the many amino acids found in soy sauce. Soy sauce is especially rich in glutamic acid, which, when combined with inosinic acid naturally present in the fish, creates a synergistic umami effect. Think of it more like an important background role to the sushi that isn’t meant to stand out.
On the other hand, overseas, sushi such as rolled sushi is generally eaten cold, and since the flavors such as sweetness, umami, and aroma fade at low temperatures. when it cools, there is a tendency to use more soy sauce. To compensate for this flavor fade, stronger seasonings such as sriracha sauce, eel sauce, and teriyaki sauce are often used, so that the flavor of the sushi does not get lost even when it cools.
There is also a big difference in the concept of sushi sauce. In Japan, there is no such word as “sushi sauce”. Neither chefs nor the general population has heard this term. However, the term is easy to imagine what it would be, so hearing the word “sushi sauce” would probably lead Japanese people to assume it meant nikiri shoyu or nitsume, which are used in nigiri sushi. Also, soy sauce, or “shoyu” as it’s called in Japanese, is not considered to be a type of “sauce” in Japan. But what about in other countries? Sushi sauce has a distinctive, assertive flavor and is added to bring out multiple layers of flavor. There are also many types of sushi sauce such as sriracha sauce, spicy mayo, mango sauce, ponzu sauce, tonkatsu sauce, eel sauce, tamari sauce, teriyaki sauce, dynamite sauce and others. They each play an important role in bringing out the flavors of sushi rolls that otherwise wouldn’t be apparent.
In other words, as the definition of sushi definition changes across borders, the definition of sushi sauce changes too. However, what both sushi sauce overseas and Shoyu in Japan have in common is that they complement the sushi they are used for.
Now we would like to explain a bit about the Shoyu used in nigiri sushi.
Edomae style sushi was created during the Edo period in Japan (1804-1830). The expansion of the soy sauce culture of the Edo area (currently Tokyo) had a big influence on the creation of Edomae style sushi. In a time when refrigeration and other technology had not yet been developed, soy sauce played an important role not only in taste, but also in preservation. A surprising number of tasks in the Edomae style utilize the scientific effects of soy sauce.
First of all, lightly applying just a small amount of Nikiri shoyu (sushi sauce) on the sushi topping brings out its natural umami flavor and also creates an attractive glossy glaze. Scientifically, this technique leverages the odor-masking properties of soy sauce, which contains sulfur-containing compounds such as methanethiol (methyl mercaptan). These compounds chemically interact with and neutralize unpleasant raw fish odors, effectively masking the “fishy” smell and enhancing the overall sensory experience.
Historically, zuke (soaking fish in nikiri soy sauce) was not limited to tuna but applied to other types of fish as well. This traditional method takes advantage of the bacteriostatic effects of soy sauce—its high salt concentration and presence of antimicrobial peptides inhibit the growth of harmful bacteria like Escherichia coli (E. coli), thereby preserving freshness and enhancing food safety.
Tsume, a thickened sushi sauce made by boiling down soy sauce with simmered conger eel sauce, mirin and sugar, demonstrates the thermal chemical reactions involved in soy sauce cooking. The Maillard reaction between amino acids from the soy sauce and reducing sugars creates a rich brown glaze and complex aroma that stimulates appetite. This reaction also contributes to the development of subtle caramelized flavors, enhancing the sauce’s depth.
Soy sauce is generally overshadowed by the sushi topping and vinegar rice, but soy sauce plays an important role in bringing out and enhancing the delicious taste of the sushi.
Related contents: SOY SAUCE FOR SUSHI
We hope this information will be helpful.
Revision date: June 13, 2025
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