Dashi shoyu vs. mentsuyu, in 2 points | sweetness and dilution, with a guide to when to use shoyu

What do you pour over chilled tofu? Mentsuyu (めんつゆ), the noodle sauce, or dashi shoyu (だし醤油)? Both are "dashi included" and wear similar faces, but each is built for a different taste. Each also has an alternate spelling in Japanese (dashi shoyu as 出汁醤油, mentsuyu as 麺つゆ), but they refer to the same things.

The difference between mentsuyu and dashi shoyu comes down to the following 2 points.

Dashi shoyu and mentsuyu differ in 2 ways

• Sweetness: mentsuyu adds sweetness with mirin or sugar. Dashi shoyu, as a rule, has none
• Dilution: mentsuyu splits into concentrated types (thinned with water) and straight types. Dashi shoyu is used as it is, in small amounts, like shoyu

Both contain dashi. The dividing lines are "sweetness" and "whether you dilute it when you use it".

Mentsuyu is designed so its taste is complete when it reaches your mouth along with the noodles; dashi shoyu lets you add dashi while using it exactly as you use shoyu. Draw that one line and the shelf sorts itself out.

What is dashi shoyu?

Dashi shoyu is shoyu combined with dashi drawn from katsuobushi, saba-bushi, kombu and the like. As with shoyu, you pour it straight over chilled tofu or egg over rice, or use it to season simmered dishes. Think of it as shoyu used for the same jobs, with the savor of dashi already inside.

Shoyu with dashi added is treated not as "shoyu" under the Japanese Agricultural Standards (JAS) but as a processed shoyu product. That is a matter of how the standards classify it, not a sign of lower quality.

Mentsuyu, for its part, refers to a liquid made by adding sugars and dashi to shoyu, used mainly as a dipping or pouring sauce for soba and udon, or as tempura dipping sauce. Under the labeling rules, the presence of sugars is part of the definition of mentsuyu. The difference in sweetness below comes straight from this difference in definition.

Difference 1: sweetness, or none

Mentsuyu takes shoyu and dashi and adds sweetness with mirin or sugar. The balance of salt and sweetness is tuned so the taste comes together when it clings to noodles on the way to your mouth.

Dashi shoyu, on the other hand, combines shoyu with dashi from katsuobushi, kombu and the like, and as a rule no sugar or mirin is added. You use it exactly as you use shoyu, pouring or simmering, and add the savor of dashi in one move: a design that stops precisely at "shoyu plus dashi".

Turn that around and you can see why mentsuyu poured straight over chilled tofu or ohitashi brings its sweetness forward. Drizzle mentsuyu over egg over rice and the aftertaste of sugar stays behind. In dishes that want the clean edge of shoyu plus dashi, dashi shoyu matches the intent better.

Difference 2: whether dilution is assumed

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

Dashi shoyu, like shoyu, is used straight, in small amounts. The label carries no dilution ratio. A few drops on chilled tofu or egg over rice, a tablespoon in a simmered dish: the amounts feel the same as shoyu.

Mentsuyu comes with dilution instructions; dashi shoyu does not. If you are unsure at the shelf, look there first. For what to check in the ingredient list when choosing a mentsuyu, see how to choose additive-free mentsuyu.

What they share: both include dashi

Note that both contain dashi. Blending in dashi from katsuobushi or kombu is common ground.

People tend to assume "dashi included, so they are the same thing", but the dividing line is this: mentsuyu adds sweetness to turn it into a noodle sauce, and dashi shoyu adds dashi without sweetness, keeping the way you use shoyu.

Tell them apart by the "name" line on the back label

When the product name on the front leaves you unsure, look at the "name" (meisho) line in the information panel on the back. A labeling guide compiled in 2013 by a shoyu industry group (the shoyu processed products liaison council, "Labeling of tsuyu") sets it out as follows.

• Mentsuyu: the name is "mentsuyu" (for products used only with noodles) or "tsuyu" (for products also used as tempura sauce, oden broth and so on). Products meant to be diluted are written "mentsuyu (for dilution)" or "tsuyu (for dilution)"
• Directions for use: mentsuyu must state how to use it, and for products meant to be diluted, the method and the ratio. Straight products state that they are used as they are
• Dashi shoyu: labeled as a processed shoyu product, under rules separate from mentsuyu. The guide also states that a product fitting the definition of mentsuyu must not be labeled a "processed shoyu product"

In other words, if the name line says "mentsuyu" or "tsuyu", it is a sweetened tsuyu; otherwise, a shoyu with dashi in it is dashi shoyu. This is a useful way to read the label when the product name just says "dashi" and you cannot tell which it is.

Mentsuyu, dashi shoyu or shoyu: a quick table

"The noodle partner" is mentsuyu; "pouring and simmering" is dashi shoyu. Put those 2 bottles at the center and everyday seasoning is nearly covered. When you want simmered dishes or soups to finish pale, shiro-dashi, which combines dashi with a pale shoyu, is the better fit.

Side by side: shoyu, dashi shoyu, mentsuyu

Line them up with shoyu included and their positions become clear.

• Shoyu: tightens with salt (no sweetness, no dashi)
• Dashi shoyu: adds dashi while used like shoyu (no sweetness, with dashi)
• Mentsuyu: complete as a noodle sauce (sweetness, with dashi)

Dashi shoyu sits right between shoyu and mentsuyu. 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 (Kansei 1). 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 (Meiji 4), 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

• 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
• Pouring and tightening with the clean edge of shoyu: shoyu

Mentsuyu is a seasoning finished as a noodle sauce; dashi shoyu adds dashi while keeping the way you use shoyu. The dividing lines are "is sweetness added" and "is it meant to be diluted". Hold those 2 apart and the shelf stops being a puzzle.

Frequently asked questions

What is the difference between mentsuyu and dashi shoyu?

There are 2 main differences. 1. Sweetness: mentsuyu adds sweetness with mirin or sugar, while dashi shoyu as a rule has no added sweetness. 2. Dilution: mentsuyu comes in concentrated types (to be thinned with water) and straight types, while dashi shoyu is used straight, in small amounts, like shoyu. Both contain dashi from katsuo, kombu and the like.

Can I use mentsuyu in place of dashi shoyu?

You can, but the sweetness comes forward. Pour mentsuyu over chilled tofu or egg over rice and the sweetness of the sugar and mirin lingers; in dishes aiming for the clean edge of shoyu plus dashi, the taste blurs. In a simmered dish you can substitute it by subtracting the sugar and mirin from the recipe, but for pour-and-eat dishes, dashi shoyu matches the intent better.

Can I use dashi shoyu in place of mentsuyu?

As a dipping sauce for somen or soba, add a little sweetness, or use it without diluting it with water. Because dashi shoyu has no sweetness, on its own it makes a dipping sauce where salt and dashi stand out a bit. For kamaage udon, chilled tofu or egg over rice, on the other hand, simply pouring dashi shoyu over settles the taste.

How do mentsuyu, shoyu and dashi shoyu differ?

Sorted into 3, shoyu is "no sweetness, no dashi" and tightens a dish with salt; dashi shoyu is "no sweetness, with dashi" and adds dashi while you use it like shoyu; mentsuyu is "sweetness and dashi" and is complete when it reaches your mouth with the noodles. Kamada Shoyu, founded in 1789 (Kansei 1), is credited with spreading dashi shoyu across the country.

Where on the label can I tell dashi shoyu and mentsuyu apart?

Look at the "name" (meisho) line in the information panel on the back. Mentsuyu is labeled "mentsuyu" or "tsuyu", and ones meant to be diluted are written like "mentsuyu (for dilution)", with the dilution ratio in the directions for use. Dashi shoyu is treated as a "processed shoyu product" (shoyu kakohin), and its name line does not say mentsuyu.

What is the difference between dashi shoyu and shiro-dashi?

Shiro-dashi combines dashi with a pale shoyu such as usukuchi or shiro shoyu, and most of it is a concentrate you dilute. Dashi shoyu keeps the color and saltiness of koikuchi shoyu and is used straight, in small amounts, poured over food or in simmered dishes. Choose shiro-dashi when you want a dish to finish pale, and dashi shoyu when you want to pour it on in place of shoyu.