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.


<Ingredients>

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


<Directions>
1.

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.

2.

(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.

<Notes>

• 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

• Shishito to eringi, myoga no miso-itame / stir-fried shishito peppers, king oyster mushroom and Japanese ginger buds with miso sauce 
• Kurumafu no katsu / gluten cake cutlets 
• Miso yasai raamen / vegetable ramen noodles with miso-flavored soup
• Ninjin no shirishiri / stir-fried shredded carrot with eggs
• Satsumaimo to ebi no tai reddo karee / Thai red curry noodles with sweet potatoes and shrimp
• Tosho chaamen / dao xiao chao mian / fried hand-shaven noodles
• Nitamago / flavored soft-boiled eggs
• Sundupu-yo yannyomu / yangnyeom seasoning mix for soondupu jjigae Korean soft tofu stew
• Tonyu miso nikomi udon / hot-pot udon wheat noodles in red miso and soy milk broth 
• Papurika to hijiki no marine / marinated sweet pepper and hijiki seaweed
  
• Okara to kinoko-iri kabocha no korokke / pumpkin croquettes with soybean pulp and mushrooms
  
• Somen no tonyu tsuketsuyu / soy milk dipping sauce for thin wheat noodles 
• Menuke to takenoko no nitsuke / rock cod and bamboo shoot in reduced broth
• Hasumushi / steamed fish with grated lotus root, with light thickened sauce
• Shiso soosu / green perilla sauce
  
• Egoma no kimuchi / kkaennip kimchi / wild perilla leaf kimchi
• Koebi no mabodofu / mapo tofu with bay shrimp
  
• Somen no tomato-iri tsuketsuyu / dipping sauce with tomato for thin wheat noodles
• Saishin no karashi oisutaasoosu-ae / yu choy sum in Japanese mustard and oyster sauce dressing
  
• Petoraaru karei no kankoku-fu pirikara-ni / braised petrale sole in mildly spicy sauce, Korean style
• Tamago fuwafuwa / steamed egg soufle over broth
• Yakinasu-iri nyumen / warm somen noodles and grilled eggplant in broth
• Warabi to eringi no iridofu / scrambled tofu with bracken and king oyster mushrooms
• Fuki to gyuniku no Kankoku-fu nimono / braised Japanese butterbur and beef, Korean style
  
• Horenso to ebi, age no shiraae / spinach, shrimp and toasted thin deep-fried tofu in tofu dressing 
• Iridori / chikuzen-ni / braised chicken with root vegetables

(Last updated: September 2, 2018)