Home » Sake Basics » Sake Making Process » The Art of Koji Making

The Art of Koji Making

Hello, fellow sake enthusiasts! Today, we’re diving deep into the heart of Japanese cuisine and fermentation – the art of koji making. But before we get into the nitty-gritty, let me take you back to my time as a sake advisor in a bustling restaurant in Carmel, CA.

A Sake Advisor’s Tale

Picture this: a busy restaurant serving hundreds of patrons daily, with one of the largest selections of sake in California. That was my playground. As a sake advisor, I was responsible for ordering sake, liaising with representatives, and recommending the perfect sake to pair with our customers’ meals.

One day, a representative introduced me to the world of koji. He explained how this humble mold, known scientifically as Aspergillus oryzae, was the secret behind the unique flavors of our beloved sake. Intrigued, I embarked on a journey to learn more about koji and its role in sake making. And today, I’m here to share that knowledge with you.

What is Koji?

Koji is a type of mold that’s been a cornerstone of Japanese cuisine for centuries. It’s used in the production of many traditional Japanese fermented foods, including miso, soy sauce, and of course, sake. The most common type of koji is rice koji, where the mold is bred on steamed rice.

To learn more about the basics of sake, check out our Sake Basics page.

Health Benefits of Koji

Koji isn’t just a flavor powerhouse; it’s also packed with health benefits. It’s rich in enzymes, amino acids, vitamins, and minerals. Plus, it’s great for gut health, contributing to a strong immune system and overall body wellness. Who knew that something so tasty could also be so good for you?

The Art of Making Koji

Now, let’s get to the exciting part – koji making. Making your own koji at home might seem daunting, but with a little patience and the right tools, it’s a rewarding process. Here’s a step-by-step guide to making your own koji:

  1. Prepare your rice: Choose a high-quality rice like Sasanishiki or Akitachomachi. Rinse it thoroughly, then soak it in water for a few hours. The soaking time depends on the temperature, but generally, 6-12 hours should do the trick.
  2. Steam the rice: Once your rice is soaked, it’s time to steam it. You want your rice to be fluffy and the grains to maintain their shape.
  3. Inoculate with koji spores: After your rice is cooked and cooled, sprinkle it with koji starter (also known as koji seed). Gently mix the rice so that the spores are evenly distributed.
  4. Incubate your koji: Place your inoculated rice in a warm, humid environment. A temperature of around 30°C (86°F) is ideal. Over the next 48-72 hours, the koji will start to grow, covering the rice with a fuzzy white coating.
  5. Harvest your koji: Once your rice is fully covered with koji, it’s ready to use! You can use it immediately, or dry it and store it in the freezer for future use.

Frequently Asked Questions About Koji Making

Now, let’s tackle some of the most common questions about koji making:

What is the best rice for making koji?

The best rice for making koji is usually a short-grain variety like Sasanishiki or Akitachomachi. These types of rice have a high starch content, which is perfect for the koji mold to feed on.

Can you make koji at home?

Absolutely! With the right tools and a bit of patience, you can make your own koji at home. It’s a fun and rewarding process, and it gives you complete control over the ingredients you use.

What do you need to make koji?

To make koji, you’ll need rice, koji starter (also known as koji seed), a steamer, and a warm, humid environment for incubation. You might also find a thermometer helpful for monitoring the temperature.

What is koji making?

Koji making is the process of growing koji mold on steamed rice. This involves preparing the rice, inoculating it with koji starter, and incubating it under controlled conditions. The resulting koji rice can be used in various Japanese fermented foods, including sake.

The Role of Koji in Sake Making

Koji plays a crucial role in sake making. It’s responsible for converting the starches in rice into sugars, which can then be fermented by yeast to produce alcohol. Different types of sake require different amounts of koji, which can influence the flavor and aroma of the final product.

For more information on the different types of sake, check out our pages on Junmai, Ginjo, and Daiginjo sake.


Koji making is an art form that’s steeped in tradition and integral to Japanese cuisine. Whether you’re a home cook looking to experiment with new flavors, a sake enthusiast wanting to understand more about your favorite drink, or a seasoned brewer, understanding and making koji can open up a world of culinary possibilities.

So why not give it a try? Who knows, you might just find yourself falling in love with the magical world of koji, just like I did all those years ago in that bustling restaurant in Carmel, CA.

Remember, the journey of a thousand miles begins with a single step… or in this case, a single grain of rice. Happy fermenting!






Leave a Reply

Your email address will not be published. Required fields are marked *