Shio koji (塩麹) is a Japanese seasoning made from fermented rice, water and salt. It can replace some of the salt while adding umami, a slight sweetness and greater depth to marinades, sauces and cooked dishes. Shio koji has become popular again in Japan in recent years, as people rediscover it and find new ways to use it.
Shio koji is a fermented Japanese condiment made from kome koji (米麹), water and salt. Kome koji is steamed rice on which the mould Aspergillus oryzae is cultivated. In Japan, it is used to produce various fermented foods such as miso, sake and amazake.
During the preparation of shio koji, the enzymes present in the koji break down some of the starches and proteins. They develop a slight sweetness, enhance umami and help tenderise meat, fish and certain vegetables.
Shio koji therefore has a more complex flavour and tastes less directly salty than salt used on its own.
Shio koji is mainly used to marinate meat, fish, tofu and vegetables.
A thin layer is enough to season the food and act on its texture. Resting time can range from around thirty minutes to overnight, depending on the ingredient and its thickness.
Before cooking over a high heat, it is best to remove any excess marinade, as the sugars produced during fermentation brown quickly.
Shio koji can also replace some of the salt in a soup, dressing, sauce, stir-fried vegetables or simmered dish. It should be added gradually, as its salt concentration varies between products.
In a marinade, it can be combined with a Japanese rice vinegar to add mild acidity, or with umesu for a fruitier, saltier flavour.
Dried kome koji requires greater precision: rehydration, proportions, temperature, preparation time and hygiene should follow the instructions provided in the recipe and for the product.
