Food · Fermented seasonings

Usukuchi Soy Sauce (Light Soy Sauce)

薄口醤油 (Usukuchi shōyu)

Also known as: Light Color Soy Sauce, Usukuchi Shōyu

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At a glance

Category	Food
Japanese labeling name	うすくちしょうゆ
Common Japanese notations	薄口醤油, うすくちしょうゆ, 淡口醤油
Origin	Fermented (soybeans, wheat, salt, water; with sweet sake or amazake addition in many recipes)
Typical functions	Light-color seasoning that preserves ingredient appearance, Salt-forward profile for kaiseki and Kansai-style cooking
Regulatory status in Japan	Standardized under the JAS standard for soy sauce. Approximately 13–15% of total Japanese soy sauce production. Higher salt content than koikuchi (typically 18–19% vs. 16–17%).

Usukuchi shōyu (薄口醤油) is Japan's lighter-colored soy sauce, developed in Kansai cuisine to season dishes without darkening their appearance. Despite its lighter color, usukuchi has higher salt content than koikuchi and is used more sparingly. Tatsuno in Hyōgo Prefecture is the historical center of production, and usukuchi remains the default cooking soy sauce in Kansai households and restaurants.

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Classification

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Product applications

Functions

Flavoring486

Regulatory tags

Culinary ingredient512

Origin

Common OEM product categories

Finished-product categories where Japanese OEM manufacturers commonly formulate with this ingredient.

Kansai-region cooking soy sauce
Pale-color simmered dishes (takiawase, soup)
Foodservice supply for Japanese restaurants

Ingredient profile

Usukuchi shōyu is brewed from approximately the same raw-material categories as koikuchi (soybeans, wheat, salt, water), but with a shorter, cooler fermentation and higher salt concentration to suppress color and Maillard browning. The fermentation is generally 6–8 months versus 12+ months for premium koikuchi.

Many traditional usukuchi recipes incorporate amazake (sweet rice ferment) or mirin during the brewing process. The ingredient list often shows amazake (甘酒) or rice as a minor component, contributing a faint sweetness and rounding the salt profile.

Hyōgo Prefecture (especially Tatsuno) is the historical and modern center of usukuchi production. Several major Japanese soy sauce brands have origins or principal production in this region.

OEM applications

Usukuchi is the default cooking soy sauce in Kansai cuisine and in kaiseki and ryōtei traditions where preserving the natural color of ingredients is a culinary priority. Clear soups (suimono), pale simmered vegetables (takiawase), and udon-noodle broth typical to Kansai are seasoned with usukuchi.

Because usukuchi is saltier than koikuchi, less is used per dish; substituting it 1:1 for koikuchi will over-salt a recipe. Recipes typically call for usukuchi explicitly when the lighter color is intended.

For OEM, usukuchi is the base for white mentsuyu, certain shabu-shabu broths, and Kansai-style dashi-based seasonings. It is also used in finished products where the soy sauce should not visibly darken the appearance of the food.

Regulatory classification in Japan

Usukuchi shōyu is a JAS-standardized variety under the Japanese Agricultural Standard for soy sauce. The standard sets compositional requirements including total nitrogen content, color, and salt level.

JAS distinguishes 本醸造 (honjozō, naturally fermented), 混合醸造 (mixed-fermentation), and 混合 (mixed) preparation methods.

Allergens: soy and wheat must be declared on labels. The Kansai term 淡口 is sometimes used in place of 薄口 on labels but refers to the same JAS variety.

Regulatory classification in other markets

EU	Imported as a fermented soy sauce. Higher salt content than koikuchi should be reflected in nutritional labeling.
USA	Imported under FDA standard food procedures. Sodium content per serving will be higher than koikuchi and should be reflected in the Nutrition Facts panel.
China	Imported under GACC rules for fermented condiments.
Korea	Imported as a fermented soy sauce; less common than koikuchi in Korean retail.

Market reference formulations

Example finished products will be added after producer's JAS classification verification.

All brand names and product names referenced anywhere on this site are the property of their respective owners. Example entries are provided for informational purposes only and do not imply endorsement.

Typical OEM use levels

Formulation ranges per finished-product application. Verify against the cited source before production.

Application	Typical range	Regulatory limit	Notes
Standard JAS usukuchi-shoyu compositional spec	Total nitrogen ≥1.15% (特級), ≥1.05% (上級), ≥0.95% (標準級)	Salt typically 18–19% (higher than koikuchi to suppress fermentation)	Lighter color, higher salt; Kansai-region preferred for dashi-led dishes(JAS 醤油規格 (平成16年9月13日農林水産省告示第1703号; 品質表示基準は第1704号))

Storage requirements

How the receiving OEM facility needs to handle inbound raw material.

Temperature: Room temperature unopened; refrigerated 4°C after opening
Conditions: Sealed; color darkens faster than koikuchi
Shelf life: 12 months unopened; 1 month refrigerated after opening

JAS 醤油品質表示基準

Supply concentration

Where this ingredient comes from — useful for single-source-risk planning.

Primary regions: Hyogo (Tatsuno — historic center for usukuchi), Kagawa
Import dependence: 100% domestic for JAS-grade

農林水産省醤油業界統計

Certifications commonly available

Certification schemes commonly obtainable for this raw material. Always confirm the specific supplier's current certificate before contracting.

Scheme	Availability
Organic JAS	Common
Halal	On-request
Kosher	On-request
Vegan	Inherent

Alternative ingredients

Related ingredients commonly evaluated as substitutes.

Quick answers

What is Usukuchi Soy Sauce (Light Soy Sauce)?: Usukuchi shōyu (薄口醤油) is Japan's lighter-colored soy sauce, developed in Kansai cuisine to season dishes without darkening their appearance. Despite its lighter color, usukuchi has higher salt content than koikuchi and is used more sparingly. Tatsuno in Hyōgo Prefecture is the historical center of production, and usukuchi remains the default cooking soy sauce in Kansai households and restaurants.
What is the regulatory status of Usukuchi Soy Sauce (Light Soy Sauce) in Japan?: Standardized under the JAS standard for soy sauce. Approximately 13–15% of total Japanese soy sauce production. Higher salt content than koikuchi (typically 18–19% vs. 16–17%).
What products typically use Usukuchi Soy Sauce (Light Soy Sauce)?: Kansai-region cooking soy sauce / Pale-color simmered dishes (takiawase, soup) / Foodservice supply for Japanese restaurants
Where does Usukuchi Soy Sauce (Light Soy Sauce) come from?: Fermented (soybeans, wheat, salt, water; with sweet sake or amazake addition in many recipes)
What is the INCI / JSCI labeling name for Usukuchi Soy Sauce (Light Soy Sauce)?: JSCI: うすくちしょうゆ

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FAQ for OEM buyers

Q. Is usukuchi soy sauce less salty than koikuchi because of its lighter color?

No — the opposite. Usukuchi has approximately 18–19% salt versus koikuchi's 16–17%. The higher salt level is part of how the fermentation produces a paler color (it suppresses microbial activity that would deepen color). Usukuchi is used more sparingly in cooking precisely because it is saltier.

Sources · Last reviewed: 2026-04-28

JAS standard for soy sauce — compositional specifications by variety

Q. Can usukuchi be substituted 1:1 for koikuchi in recipes?

Not directly. Because usukuchi is saltier, a 1:1 substitution will over-salt the dish. The two are also visually different — usukuchi preserves the color of light ingredients while koikuchi darkens them. Recipes calling for usukuchi typically depend on both the salt level and the color preservation.

Sources · Last reviewed: 2026-04-28

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References

JAS standard for soy sauce (しょうゆの日本農林規格)
Tatsuno-shi (Hyōgo) light soy sauce industry documentation
文部科学省 (Ministry of Education, Culture, Sports, Science and Technology) Standard Tables of Food Composition — usukuchi soy sauce (17008, 17139)

Last updated: 2026-04-28. Ingredient entries are reviewed at least annually against current regulatory listings.