Nihon Chomiryo Tabi
How to use usukuchi shoyu
- In one line: use it in dishes where you do not want to add color. You choose it for the color of the finished dish, not for a milder taste.
- When swapping in for koikuchi, start at about 80% of the amount, not one for one. Usukuchi runs about 18% salt, saltier than koikuchi at about 16%.
- Usukuchi is not a reduced-salt shoyu. The "usu" in usukuchi points to the color, not the taste.
- A pale color makes the taste seem lighter, but that is your eyes leading your tongue. Pale color and salt content are unrelated.
You bought a bottle of usukuchi shoyu (soy sauce), and it has been sitting in the fridge because you were not sure what to do with it. Or you went to order one online and there were too many to choose from. We hear both often.
The use, in one line: it goes in dishes where you do not want to add color. That is the whole of it. Below, a dish-by-dish guide, the amount to use when you swap it in for koikuchi, and what to check when you order online.
Usukuchi or koikuchi, dish by dish
When in doubt, follow the table and you will not go wrong.
| Dish | Which to use | Why |
|---|---|---|
| Clear soup, suimono | Usukuchi | The dashi stays clear |
| Takiawase, simmered vegetables | Usukuchi | Vegetable colors do not sink |
| Dashimaki tamago, chawanmushi | Usukuchi | The yellow of the egg lives |
| Blanched greens | Usukuchi | The green does not dull |
| Rice cooked with other ingredients | Usukuchi | The rice does not go brown |
| Udon broth, Kansai style | Usukuchi | It finishes clear |
| Sashimi, sushi | Koikuchi | Aroma and depth lead |
| Teriyaki, fish simmered in shoyu | Koikuchi | You want the color and gloss |
| Stir-fries | Koikuchi | You need the toasted note |
| Simmered dishes you want brown | Koikuchi | It gives the familiar color |
The line is clear. If you want the finished dish to stay close to clear, usukuchi; if you want it dark and brown, koikuchi. Choose by color, not by how strong you want the seasoning.
How much to use when swapping in for koikuchi
When a recipe says one tablespoon of shoyu and you want to use usukuchi, start at about 80% rather than the same amount.
| Koikuchi in the recipe | Usukuchi instead |
|---|---|
| 1 tbsp (15ml) | 2.5 tsp (about 12ml) |
| 2 tbsp | Just under 1.5 tbsp |
| 1 tsp | 0.8 tsp |
The reason is salt. Usukuchi runs about 18% salt, koikuchi about 16%. Usukuchi is the saltier of the two, so a one-for-one swap makes the salt stand up too far.
You can always add more; salt you have already put in cannot be taken out. Go light, then taste. Keep that order and the swap will rarely fail you.
One more thing: because the color is pale you will feel the taste is thin and want to add more, but that is your eyes leading your tongue. Pale color and salt content are unrelated.
The idea that usukuchi means mild
This is the most common misreading, so let us be blunt.
Usukuchi shoyu is not a reduced-salt shoyu. Its salt sits above koikuchi. The "usu" in usukuchi points to the color, not the taste.
Keeping the color pale means holding fermentation back, and salt is what does that job. A stronger brine at brewing, and a shorter aging period. The higher salt is what a pale color costs.
Choose usukuchi to cut salt and you get the opposite of what you wanted. If you want less salt, buy a shoyu labeled as reduced-salt.
Finishing a bottle of usukuchi
People often tell us they bought it for Japanese cooking and now cannot get through it. Think of usukuchi as salt that adds no color and the uses open up at once.
- Soups and potages: in place of salt. It adds savor without clouding the color
- Pasta: to season Japanese-style pasta. The shoyu smell stays in the background
- Marinating chicken breast: for a saute where you do not want browning
- Quick pickles: vegetable colors stay bright
- Rice with a raw egg: the yolk keeps its color
After opening, keep it in the fridge and use it within 1 to 2 months. Contact with air oxidizes it and darkens the color, and the reason you chose usukuchi is gone. Do not leave it out on the table.
Usukuchi was born in Tatsuno
The area known for usukuchi shoyu is Tatsuno (龍野) in Harima, now Tatsuno City in Hyogo Prefecture. It is said to have appeared in the early Edo period.
The place had everything a pale shoyu needs. The water of the Ibo River (揖保川) is soft and low in iron, so the shoyu is slow to darken. The Banshu plain grew rice and wheat, and Ako nearby had salt. Usukuchi from Tatsuno traveled to Kyoto and Osaka, where it supported the Kyoto and kaiseki cooking that prizes the flavor and color of the ingredients themselves.
Koikuchi in the Kanto region grew up alongside Edo soba and grilled eel; usukuchi in Kansai grew up alongside dashi. The east-west split in shoyu is the east-west split in how people eat.
The craft of not adding color
The paleness of usukuchi shoyu is not the result of cutting corners. If anything the opposite: work goes into keeping the color out.
Brewing in a stronger brine slows fermentation, and a shorter aging period keeps the color from deepening. Some breweries also use rice to round out the taste. The higher salt follows from that same choice to hold fermentation back.
Not diluted, but kept pale. Usukuchi is shoyu by subtraction.
Under the JAS standard, shoyu is divided into five types: koikuchi, usukuchi, tamari, saishikomi, and shiro. Usukuchi sits at the end of that range where color is held down the furthest.
What to check when you order usukuchi shoyu online
Supermarket shelves carry few usukuchi options, so this is a category many people end up buying online. There are three things worth checking before you order.
- Origin: bottles from Tatsuno City in Hyogo Prefecture, where usukuchi began, are the baseline. The soft water of the Ibo River and the salt of Ako are what gave rise to usukuchi
- Ingredients: does the label say whole domestic soybeans and domestic wheat? Defatted soybeans can make shoyu too, but whole beans give more body to the savor
- Brewing: does it say tennen jozo (naturally brewed, no temperature control)? The clarity of the color differs from mass production that applies heat and finishes in a short run
For size, we would start with a mid-size bottle around 500ml. Usukuchi is a shoyu you want to finish within 1 to 2 months of opening, so a 1-liter bottle tends to darken before you get to the end. Compare prices with shipping included and this size band is the one least likely to disappoint.
Suehiro Shoyu Honzukuri Usukuchi Shoyu: a bottle from the birthplace, available online
The bottle that meets all three conditions above is Honzukuri Usukuchi Shoyu from Suehiro Shoyu in Tatsuno.
- Origin: Tatsuno City, Hyogo Prefecture, where usukuchi began
- Ingredients: 100% whole domestic soybeans and domestic wheat
- Brewing: tennen jozo, continuing since 1879 (Meiji 12)
- Size: 500ml, a mid-size bottle that is easy to finish
Rather than applying heat to hurry fermentation along the way mass production does, the brewing here leaves the pace to the temperature of the seasons. Make a simmered dish with dashi and this shoyu and it finishes like a ryotei takiawase, with the color of the dashi showing straight through.
A Kanto kitchen used to koikuchi is exactly where the difference will land hardest. You can order it from the product page (details of Suehiro Shoyu Honzukuri Usukuchi Shoyu).
If you also want a koikuchi on the shelf, Inoue Shoyuten Koshiki Joyu from Okuizumo in Shimane, founded 1867, makes a good partner for simmered dishes, letting you use usukuchi and koikuchi by purpose.
One dish to start with
For a first try, we would suggest a clear soup. The color of the dashi stays as it is, so the effect of usukuchi shows up more plainly than anywhere else.
Take your usual dashi, a pinch of salt, and a scant teaspoon of usukuchi. That alone gives you the clear bowl you get served at a ryotei. Make the same soup with koikuchi, set them side by side, and the gap in color will surprise you.
One more bottle on the shelf, and Japanese dishes come out visibly different.
Frequently asked questions
What dishes should I use usukuchi shoyu in?
It suits Japanese dishes where you want the dashi or the ingredients to keep their color: clear soups, takiawase, simmered vegetables, dashimaki tamago, and blanched greens. The effect is clearest when you want simmered dishes to finish as pale as they do in a ryotei. For sashimi, teriyaki, and fish simmered in shoyu, where the color and aroma of the shoyu are the point, koikuchi is the better choice.
How much usukuchi shoyu do I use in place of koikuchi?
For 1 tablespoon of koikuchi, start with 2.5 teaspoons of usukuchi (about 80%), taste, and add more if needed. Usukuchi runs about 18% salt against roughly 16% for koikuchi, so a one-for-one swap comes out salty. The color gets paler, but the salt does not go down.
Is usukuchi shoyu lower in salt?
No, and it is the other way around: usukuchi tends to be higher in salt. To keep the color pale, it is brewed in a stronger brine that holds fermentation back, and that pushes the salt up. The "usu" in usukuchi refers to color, not to taste. If lower salt is your aim, buy a shoyu labeled as reduced-salt.
What is the difference between usukuchi and koikuchi shoyu?
Color and salt. Usukuchi is pale, so it suits cooking where you want the ingredients and the dashi to keep their color. Salt runs the other way: koikuchi is generally about 16% while usukuchi sits nearer 18%. Usukuchi does not mean mild or reduced-salt.
I have usukuchi shoyu left over. How do I use it up?
It goes well beyond Japanese cooking. Use it in place of salt to season soups and pasta and it adds savor without clouding the color. It also suits marinating chicken breast, quick pickles, and rice with a raw egg. After opening, keep it in the fridge and finish it within 1 to 2 months. Contact with air darkens the color, which undoes the reason you chose usukuchi.
What should I look at when buying usukuchi shoyu online?
Three things: where it is made, what is in it, and how it is brewed. For origin, bottles from Tatsuno in Hyogo Prefecture, where usukuchi began, are the baseline. For ingredients, look for whole domestic soybeans and domestic wheat stated on the label. For brewing, "tennen jozo" (naturally brewed, no temperature control) is said to give the best balance of color and savor. A mid-size bottle around 500ml is easy to finish in 1 to 2 months and is a sensible size to order once shipping is factored in.
