All recipes are for 2 servings unless noted. Oil is canola oil and salt is kosher salt.


Shoyukoji / soy sauce rice malt

Shoyukoji is technically the base of soy sauce in the production process (see Kikkoman website). However, today the term is more commonly used to mean a mixture of shoyu soy sauce and koji rice malt, which has become popular in the last few years in Japan and among the Japanese community overseas. Just like shiokoji salted rice malt, shoyukoji is full of umami. In fact, its glutamic acid content is said to be 10 to 15 times of that of shiokoji.

Shoyukoji takes full advantage of the characteristics of soybeans, the main ingredient of soy sauce, resulting in excellent aroma as well as mellow yet salty taste. Its sweet note lets you cut back on sweeteners such as sake, mirin and sugar in your dishes. And just as with shiokoji and koji-based amazake, shoyukoji tenderizes meat and fish. Moreover, because it is made by mixing with virtually sodium-free koji rice malt, the overall sodium content of shoyukoji is lower than that of soy sauce itself (in the following recipe, sodium content of shoyukoji is around 65% of that of soy sauce). When using shoyukoji for cooking, you can replace at least half of soy sauce in a recipe with shoyukoji without compromising the taste of the final dish.


150 cc (180 g) soy sauce of your choice
100 g koji rice malt (dry type in photo)


In a container, mix soy sauce and koji rice malt, cover, and let sit at room temperature for 1-2 weeks until mixture becomes a miso-like paste.

Mix at least once a day to let it breathe.

(Day 2)
Mixture looks dry, but do not add water or soy sauce.

(Day 4)
After several days, mixture has started to blend together.

(Day 7)
Basically ready.

When koji is soft and easily mashed, it is ready for use.

If preferred, you can puree the mixture.
Keep refrigerated.

  • If in hurry, shoyukoji can be made by keeping the mixture at 60C/140F for 3-4 hours (photo at right) using the "keep warm" function of a rice cooker (cover of rice cooker should be kept open and pot covered with moistened cloth; some water needs to be added, as moisture tends to evaporate during heating). 
  • A hot bath for an hour or two in the middle of making shoyukoji can also speed the process. In photo at left, after being kept on the kitchen counter for a week, koji rice malt in the shoyukoji mixture was still gritty, and the whole jar (with cap closed) was soaked in hot water (60 C/140 F) in a rice cooker ("keep warm" function; rice cooker cover is kept open but covered with a cloth) for 1+ hours, resulting in perfectly soft koji.
  • Nutrition values, especially sodium content, of shoyukoji vary significantly according to the soy sauce you use. Below are examples per 1 tbsp shoyukoji. The weight of shoyukoji varies by source; in my case it is 20 g/1 tbsp on average.
    • Made with Kikkoman Marudaizu Genen (Milder Soy Sauce; 470 mg sodium/1 tbsp): 41 calories; 1.51 g protein; 0 g fat; 8.0 g carbohydrate; 332 mg sodium; 0 mg cholesterol; 0.1 g fiber
    • Made with Yamasa Marudaizu Shoyu (940 mg sodium/1 tbsp): 37 calories; 1.4 g protein; 0g fat; 7.4 g carbohydrate; 661 mg sodium; 0mg cholesterol; 0.1 g fiber
    • Made with Yamasa Usukuhchi Shoyu (1150 mg sodium/1 tbsp): 35 calories; 1.2 g protein; 0g fat; 7.2 g carbohydrate; 830 mg sodium; 0mg cholesterol; 0.1 g fiber
    Aim to use less; it makes a big difference! If it is 18 g/1 tbsp, the sodium content above would be 299 mg with Kokkoman Marudaizu Genen, 595 mg with Yamasa Marudaizu Shoyu, and 747 mg with Yamasa Usukuchi Shoyu.

Recipes with shoyukoji

(Last updated: April 21, 2018)

No comments: