Mentsuyu vs. shoyu, in 3 points | sweetness, dashi, dilution (and dashi shoyu from Kamada Shoyu, founded 1789)

What do you pour over chilled tofu? Shoyu (soy sauce), or mentsuyu (めんつゆ), the noodle dipping sauce? They wear similar faces, but each is built for a different taste.

The difference between mentsuyu and shoyu comes down to the following 3 points.

Mentsuyu and shoyu differ in 3 ways

• Sweetness: shoyu has no sweetness. Mentsuyu adds it with mirin or sugar
• Dashi: shoyu contains no dashi. Mentsuyu has katsuo or kombu dashi blended in
• Dilution: shoyu is used as it is, in small amounts. Mentsuyu splits into concentrated types (thinned with water) and straight types

Shoyu tightens a dish with salt. Mentsuyu is complete only when it reaches your mouth along with the noodles. Draw that one line and the way the shelf is divided becomes visible.

Difference 1: sweetness, or none

Shoyu, as a rule, has no sugar or mirin added. It is a seasoning for pulling a dish together with salt and the savor that comes from fermentation.

Mentsuyu, on the other hand, adds sweetness with mirin or sugar on top of shoyu and dashi. Salt and sweetness are balanced so the taste comes together as you lift the noodles to your mouth.

Turn that around and you see why pouring mentsuyu straight over chilled tofu or blanched greens pushes the sweetness forward. On sashimi it leaves a trailing note of sugar. Where you want the clean edge of shoyu, shoyu matches the intent better.

Difference 2: dashi, or none

The other large difference is dashi. Shoyu contains none. Combining it with katsuobushi or kombu is the cook's job.

Mentsuyu has katsuobushi or kombu dashi blended in from the start. The reason it works so completely as a noodle sauce is that the step of drawing dashi has already been done for you.

Shoyu with dashi added, incidentally, is said to fall outside "shoyu" under the Japanese Agricultural Standards (JAS) and to be handled as a shoyu-based processed product. That is not a statement about lower quality; it is a matter of how the standard sorts things.

Difference 3: whether dilution is assumed

Shoyu is used as it is, in small amounts. No dilution ratio appears on the label.

Mentsuyu comes in 2 kinds. Concentrated types (2x, 3x, 4x and so on) are thinned with water or dashi, while straight types are used as they are. The front of the package always says either "x-fold concentrate" or "straight," so that is where you can tell them apart.

Shoyu carries no dilution instruction; mentsuyu does. When the shelf leaves you unsure, that is the fastest thing to check.

A quick table: which to use when

Pouring and tightening is shoyu; the noodle's partner is mentsuyu. When you want one bottle to do both jobs, what appears is the dashi shoyu covered next.

Dashi shoyu, the option in between

Between shoyu and mentsuyu sits one more genre: dashi shoyu.

Dashi shoyu is shoyu blended with dashi from katsuobushi, kombu and the like, with no sugar or mirin as a rule. You use it the way you use shoyu, pouring or simmering, and add the savor of dashi in one move. It is a design that stops at shoyu plus dashi.

• Shoyu: tightens with salt (no sweetness, no dashi)
• Dashi shoyu: lets you add dashi while using it like shoyu (no sweetness, dashi yes)
• Mentsuyu: complete as a noodle sauce (sweetness yes, dashi yes)

In a household that does not need both shoyu and mentsuyu on hand, a useful pairing is to cover the everyday pouring and simmering with a single dashi shoyu and reach for mentsuyu only on noodle days.

Kamada Shoyu dashi shoyu: the bottle that spread the category

Dashi shoyu is now taken for granted as a category. The maker known for breaking that ground is Kamada Shoyu, in Sakaide, Sanuki.

It was founded in 1789. The dashi shoyu that came out of a brewery brewing shoyu for over 230 years combines honjozo shoyu with a first dashi of katsuobushi, saba-bushi and kombu. Every step, from handling the raw ingredients through fermentation, aging and filling, happens within the city of Sakaide.

In Kagawa, the udon prefecture, the relationship between dashi and shoyu is everyday life itself. Pour it, drip it, and a dashi-forward taste is settled: that convenience has long made it a gift as well. Chilled tofu, egg over rice, both finished with this one bottle.

Mentsuyu you do not dilute: Yamae Takachihokyo Tsuyu

One more, from the mentsuyu side. "Takachihokyo Tsuyu Umakuchi" from Yamae Shokuhin Kogyo in Miyakonojo, Miyazaki, is a straight-style tsuyu combining katsuo dashi with honey. It is the flagship product that led sales among straight tsuyu in Kyushu for 9 years running, and it is used undiluted on somen and in hiyajiru.

Founded in 1871, the brewery has been making miso and shoyu for over 150 years, using groundwater from the Kirishima range as its brewing water. The "umakuchi" in the name is a Kyushu shorthand for a taste that is neither dry nor sweet.

Its sweetness comes from honey rather than sugar. That is the source of the rounded sweetness you notice when it clings to somen.

In short: how to decide at the shelf

• Mostly pouring and tightening: shoyu
• Noodles often, and you want to skip the work of settling the taste: mentsuyu (pick concentrated or straight by how often you use it)
• One bottle to cover pouring and simmering, dashi included: dashi shoyu

Shoyu tightens a dish with salt; mentsuyu is finished as a noodle sauce; dashi shoyu sits between them, stopping at shoyu plus dashi. Hold those apart and the shelf stops being a puzzle.

Frequently asked questions

What is the difference between mentsuyu and shoyu?

There are 3 main differences. 1. Sweetness: shoyu has no sweetness and tightens a dish with salt, while mentsuyu adds sweetness with mirin or sugar. 2. Dashi: shoyu contains no dashi, while mentsuyu has katsuo or kombu dashi blended in. 3. Dilution: shoyu is used straight, in small amounts, while mentsuyu comes in concentrated types (to be thinned with water) and straight types.

Can I use mentsuyu in place of shoyu?

You can, but the sweetness and dashi come forward ahead of the dish. With something like chilled tofu or sashimi, where you want the clean edge of shoyu, the taste tends to blur. In a simmered dish you can substitute it by subtracting the sugar, mirin and dashi from the recipe, but for pour-and-eat dishes such as egg over rice or sashimi, shoyu or dashi shoyu matches the intent better.

Can I use shoyu in place of mentsuyu?

On its own it falls short as a dipping sauce for noodles. Add dashi, mirin and sugar to shoyu and you can get close, but you lose the convenience. A bottled mentsuyu has already been tuned to land just right when it enters your mouth together with the noodles, and that is its main job.

Is there something between shoyu and mentsuyu?

That is dashi shoyu. It is shoyu blended with dashi from katsuobushi or kombu, and as a rule it carries no added sweetness. You use it exactly as you use shoyu, pouring or simmering, and get the savor of dashi in one move. Kamada Shoyu, founded in 1789, is credited with spreading dashi shoyu across the country.