Why Are Top Chefs Worldwide Raving About Koji
Image Credit: Koji | Image Credit: Google

Japanese koji is a cult ingredient that has been embraced by top chefs around the world. That’s because it produces umami-rich and unique artisan cheeses that have an intense, earthy aroma. These flavors can be found in such delicacies like miso, sake, soy sauce etc. However, many people are unaware of this or don’t know how to incorporate them into their cooking. In this article we’ll discuss what koji is, where to buy it, how to use it, and its benefits for your health.

What is koji?

The term "koji" is used to describe the process of fermentation of the fungus Aspergillus oryzae and the components used for fermentation, such as rice, soybeans, and wheat. The process of preparing Koji involves adding a special type of mold to steamed grains such as rice, barley, and soybeans. This is then carefully grown in a warm and humid environment, which encourages the proliferation of the spores.

These spores are only 3–10 micrometers in size (1 μm = 0.001mm). In 2006, the Brewing Society of Japan designated Koji as a "valuable asset carefully nurtured and used by our ancestors" and declared it the National Mold of Japan. Ancient people caught on to the value of the Koji mold and used it for making items such as miso, soy sauce, and Japanese sake.

Types of koji used in cooking

There are various types of koji that are popularly used in Japanese cooking and around the world.

Rice Koji

Koji that is cultured on rice and is full-flavored with a rich color and less sweetness compared to barley or soybean.

Barley Koji

This is a lower-molecular-weight koji, with more sweetness and less umami than the other two types of koji.

Soybean Koji

Soybean koji is relatively high in umami and has a lighter color than the other types of koji.

You can also make your own koji at home. You can purchase koji culture kits, which include the grains, a jar for storage, and instructions on how to culture and use the koji.

Koji molds that are used while cooking

1.    Yellow koji mold

It is mainly used while cooking miso, soy sauce, and refined sake. The spores are yellow, light green, or yellowish brown.

2.    White koji mold

This type of koji is used in the production of shochu. The color of the spores is brown.

3.    Black koji mold

This koji is used in the production of "awamori" (Okinawa liquor). The color of these spores is blackish brown.

4.    Red koji mold

It is used for producing tofu-yo, Chinese red wine, and Shaoxing wine. It produces bright red koji.

5.    Bonito mold 

This type of koji is used in the production of katsuobushi (dried bonito). Koji absorbs katsuobushi residue moisture, imparts umami flavor, and breaks down fats and oils.

Why use koji in cooking?

Umami is a flavor that is very important in the making of artisan cheeses as well as other fermented food products such as miso and kimchi. Koji is used to culture foods to add umami, or "savory," flavors and improve the microbial diversity. There are three kinds of umami: the primary umami (monosodium glutamate or MSG), the secondary umami (l-glutamate or l-glutamine), and the tertiary umami (polysaccharides or enzymes). These umami flavors are found in foods such as meat, fish, vegetables, and grains. Koji helps cultivate these umami flavors. It also creates many other beneficial compounds, such as vitamin B and antioxidant polyphenols.

How to use koji in cooking

There are a variety of ways one can incorporate koji into their cooking. You can use it in soups as an amino acid source, or add it to your favorite fermented vegetables or dips.

You can also use koji in your favorite baked goods, such as breads, muffins, and pastries. You can even use koji to produce yogurt and cheese.

Where to buy koji

Koji can be found in select grocery stores or online. It is best to buy it in small quantities (1 to 2 pounds) so that it is easier to store for future use.

How to make your own koji

This process is similar to making miso.

Put the grains in a jar or container. Pour in enough water to cover the grains by 1/2 to 1 inch.

Cover the jar with a cloth or paper towel, and keep it at room temperature for 3 to 4 days, stirring it twice a day (you can use the same cloth or paper towel you used for the mineral water).

At the end of this fermentation period, you will have koji. Transfer the koji grains to a jar or container and keep them in the fridge for future use.