If you’ve never made shio koji at home, you’re in for a treat. This Japanese seasoning is a fantastic alternative to plain salt—salty, yes, but also rich in umami with a touch of natural sweetness that adds real depth to your cooking.

I often use it to marinate meat overnight—it makes it incredibly tender, juicier, and full of flavor.

While it does take some time to ferment, the process is simple and even a bit meditative. And the best part? Once it’s ready, a batch of shio koji will keep for months in the fridge (it just never seems to go bad), so you’ll always have this flavor booster on hand when you need it.

sakura yubi in kitchen stirring shio koji in a jar

How to Make Shio Koji

Shio koji is a Japanese seasoning that adds saltiness, umami, and a hint of sweetness to dishes. I use it often to marinate meat overnight—it makes everything more tender, juicy, and flavorful—and once made, it keeps for months in the fridge.

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Sakura Yubi

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Prep Time 20

Fermentation Time 10

Total Time 10 20

Cuisine Japanese

Course Seasoning

Servings 28 tablespoons

Ingredients

200 g (1.08 cups) rice koji
60 g (2.12 oz) salt
300 ml (1.27 cups) water

directions

First Day

Prepare warm water below 60 °C (140 °F).
Make sure the water is not too hot, otherwise, you will kill the enzymes in rice koji which will be added later, and the fermentation will not work.
In a container, add salt, and then add the warm water.
Add rice koji and mix well.
After everything is mixed well together, put the lid on the container. Leave the container at room temperature and let the mixture ferment.
The rice koji will quickly absorb all the water, but in time, the water will come back out.

Second Day and Onwards

On the next day, stir the mixture, put the lid back on, and leave it at room temperature. Repeat this process every day for about one to two weeks or until your shio koji is ready.
Stirring will redistribute the salt content evenly and prevent molding. If you don't stir regularly, the salt will sink to the bottom and bacteria will start to grow at the surface, which will lead to molding.
The fermentation speed will depend on the temperature.
Your shio koji is ready when it's liquidy like a paste, has a mild salty taste with umami and sweetness, and can be easily crushed with your fingers.

Recipe Notes

The ratio of the ingredients doesn’t have to be exact. The salt in shio koji, however, has an important role in preventing molding, so don’t decrease the percentage of salt too much.
You can store shio koji in the refrigerator or freezer to keep it fresh for many months. You can also store it at room temperature, but make sure you stir it regularly to prevent molding. Read more about it at What Is Shio Koji? (The Complete Guide)

Nutrition

Serving: 1tablespoonCalories: 27.1kcalCarbohydrates: 6gProtein: 0.6gFat: 0.1gSodium: 830.5mgPotassium: 0.2mg

Keyword koji salt, salt koji, seasoning, shio koji

Sakura Yubi

Tokyo-based Japanese home cook and food writer, sharing easy, low-carb recipes featuring Japanese staples like shio koji. I also explore the city’s dining scene through honest restaurant reviews and food adventures. Learn more at sakurayubi.com/about.

How to Make Shio Koji