Koji is a beloved fungus in Japanese delicacies due to its function in producing sake, miso, soy sauce, rice vinegar, and lots of extra umami-packed components. Koji belongs to the Aspergillus genus, however in contrast to a few of its poisonous cousins, Koji doesn’t produce aflatoxin, making it secure to devour (3).

Not too long ago, many cooks have experimented with utilizing koji in novel methods, such because the koji-encrusted pork by Chef Jeremy Umansky of Larder: A Curated Delicatessen & Bakery. Historically, koji is used primarily to ferment grains and soybeans, however curious cooks have proven that these fungi can increase the flavour profile for meats and sauces (1,2).

To learn extra in regards to the science behind Koji, go to this post by Bryan Quoc Le.

Even should you aren’t close to a restaurant serving koji-encrusted meats, you possibly can truly make your personal batch of koji at dwelling. Because the tradition is alive, it takes some care to make sure undesirable molds and micro organism don’t out-compete the koji. Although it’s attainable to tradition koji and not using a starter, it may be difficult for learners to find out whether or not the aesthetic mildew is the fitting species. If that is your first time making koji tradition, it’s safer to buy a koji tradition starter and get a really feel for the mildew earlier than gathering your personal spores.

Koji tradition may be bought at some Oriental grocery shops, but when there’s none close by, you too can buy it on-line by looking out “koji starter tradition” or “koji kin starter”. Some manufacturers will promote dried koji-rice (malted rice) slates, which may be “activated” by including water. One of these starter is nice should you do not need time to begin a tradition from rice grains. Because the koji has already been seeded with the rice, it cuts down the prep work of steaming rice. After the starter has been activated, which often takes round one to 3 weeks relying on the temperature, it may be used to marinate meats or as an ingredient for salad dressings.

One other sort of tradition you should purchase is the koji-kin, which is analogous to sourdough yeast starters. Like yeast, koji-kin additionally seems as a evenly coloured powder, although this powder comprises dried koji spores as an alternative of baker’s yeast. Additionally, in contrast to the earlier technique of utilizing a koji-rice slate, beginning a tradition from koji spores will take extra time, however can be a helpful expertise in case you are seeking to create your personal koji spores in the long term.

Since there are a number of methods to make koji, this can be a technique described by Japanese koji-makers. Making koji from koji-kin is a labor-intensive course of, so make sure that to plan your steps forward of time. The fermentation course of can take 45-50 hours. Fortunately, many of the work is finished by the koji, and you’ll simply have to investigate cross-check it each few hours.

What you have to:

  • 500 g rice (Historically makes use of quick grain white rice)
  • Comfortable water (Stick to producer’s beneficial hardness of water, if relevant )
  • Three g koji-kin
  • Three clear steam material/cheese material
  • Thermometer
  • Metallic tray or pan
  • Strainer
  • Koji Incubator* (See “Notes” for the right way to arrange your personal incubator)

Beginning your koji tradition:

  1. Rinse the rice with water to take away extra starch, after which immerse the rice in delicate water. Soak in a single day within the fridge.
  2. Pressure the soaked rice and take away as a lot water as attainable.
  3. Wrap the rice in a clear material and switch it to a steamer. If utilizing a bamboo steamer, take away the lid for the primary 5-10 min to make sure steam is rising, after which shut the lid, letting the rice steam for 40-45 min on excessive warmth. Rice ought to be barely firmer than absolutely cooked rice, however not undercooked such that the middle of the rice remains to be white.
  4. All steps after this require very clear fingers. Wash your fingers earlier than finishing any of the next steps to keep away from contaminating your rice.
  5. Instantly switch the steamed rice to a brand new clear material on a clear tray or pan and let cool by gently folding the rice to launch steam.
  6. Koji-kin could be very tremendous, so don’t do that step close to a fan or AC system. As soon as the rice has cooled to 36 levels C, sprinkle a number of the koji-kin onto the rice and blend the rice and koji-kin along with your fingers. Repeat till all of the koji-kin has been integrated. Break aside any clumps of rice. Do that step rapidly to keep away from over-cooling the rice.
  7. Wrap the koji-rice combination with the material tightly and incubate the combination at 32-35ºC for 18-22 hrs. Having a bowl of water within the incubator ensures that the koji-rice doesn’t dry out whereas fermenting. Wipe away any condensation on the lid to keep away from water dripping onto the koji.

Determine 2. Koji progress on rice. Courtesy to fo.ol (https://flic.kr/p/52g5ZW)

  1. After 18-22 hrs, there can be small white speckles on the rice, indicating koji progress. Unwrap the material and gently break aside any clumps of rice rapidly to forestall the temperature from dropping too low. Re-wrap the koji-rice combination and return to the incubator for Three hrs.
  2. After Three hrs, the koji-rice ought to have a candy scent. Verify if the rice is at 40 levels C. If not, set to a barely larger temperature or wait a few hours.
  3. As soon as the rice is round 40 levels C, unwrap the koji-rice and break aside all clumps, transferring the damaged up items into one other clear tray or pay. Evenly unfold out the koji-rice and canopy with a humid material. Return koji-rice to the incubator for 5-6 hrs, or till the rice has once more reached 40 levels C.
  4. Take out the tray and break aside any clumps. Permit the temperature of the koji-rice to drop to 38 levels C earlier than returning the tray to the incubator. Keep in mind to cowl the tray with a humid material.
  5. After Three hours, if the koji-rice has reached 40 levels C once more, take out the tray and break aside any clumps. At this level, the koji-rice ought to have a robust candy scent.
  6. Return the tray into the incubator with out protecting with a humid material and let it ferment for six hrs.
  7. After 6 hrs, improve the temperature of the incubator in order that the rice can be at 40-42 levels C. Let it ferment for an additional 6 hrs.
  8. As soon as the fermentation is full, you need to have a dry koji-rice slate. In the event you look carefully, you need to see fluffy white koji rising on the rice grains. Break aside the clumps and let cool earlier than storage.
  9. To retailer your koji tradition, switch it right into a freezer bag and freeze for as much as Three mo. If utilizing instantly, you possibly can retailer it within the fridge for as much as Three weeks.

Recipes to attempt along with your koji tradition (Begin right here if utilizing the koji-rice slate starter):

Ama-zake (candy sake): Cook dinner 150g of white rice right into a porridge with the consistency of mayonnaise (takes round 300 mL of water, however modify as wanted). Let the porridge cool to 60 levels C. This step is essential as a result of the enzymes will deactivate should you add the koji when the porridge remains to be scorching. As soon as the porridge is cooled, mix with 200 g of your koji-rice starter and hold heat (50~60ºC) for 8-10 hrs, stirring each Three hours. In case your container doesn’t have a lid, cowl with a clear material. As soon as completed fermenting, you possibly can mix the combination for a clean mouthfeel or you possibly can drink it as is. This drink may be served scorching or chilly.

 Determine Three Amazake. Courtesy to Nobuyuki Hayashi https://flic.kr/p/bDGVSM

Shio-koji (salted koji): Add 60 g of salt to 300 mL of water and heat till 60 levels C. In a clear zip-lock bag, add the koji-rice starter and heat salt water, and blend properly. Depart the combination at room temperature (ideally between 25-30 levels C), and stir the combination as soon as day by day till it reaches a thick consistency, round 1-2 weeks.

As soon as the shio koji is prepared, you should utilize it to salt salads or marinate meat. Change fried rooster marinades with shio-koji, and go away it within the fridge for 3-Four days earlier than frying like ordinary. It’s also possible to marinate any vegetable, like cucumbers and carrots, in shio-koji in a single day and serve it as pickles.

Determine 4. Shio-koji cucumbers. Courtesy to Tatsuo Yamashita (https://flic.kr/p/bq4tiY)


In the event you do not need a koji incubator, you can also make one with a cooler and a few type of heater with an adjustable temperature setting. Try this resource from FermUp for how one can arrange your personal.

The generally offered koji-kin has a white or off-white coloration; nevertheless, koji-kin can are available quite a lot of colours together with inexperienced, crimson, and even black. In the course of the koji making course of, in case you are not sure whether or not you may have cultured koji or one other mildew, examine with the producer for what coloration your koji ought to be in addition to detecting whether or not the odor from the rice is good. When not sure what you may have cultured, it’s most secure to redo the method once more.


  1. Graber, C. Koji https://www.cooksillustrated.com/science/786-articles/feature/koji (accessed Jul 26, 2020).
  2. Katayama, A. Western Cooks Are Discovering And Reworking Koji Tradition https://www.forbes.com/sites/akikokatayama/2018/10/28/western-chefs-are-discovering-and-transforming-koji-culture/ (accessed Jul 26, 2020).
  3. Machida, M.; Yamada, O.; Gomi, Ok. Genomics of Aspergillus Oryzae: Studying from the Historical past of Koji Mould and Exploration of Its Future. DNA Res 2008, 15 (4), 173–183. https://doi.org/10.1093/dnares/dsn020.
  4. 米麹(米こうじ)の作り方|初めてでも失敗しない動画付き. https://kawashima-ya.jp/contents/?p=459 (accessed Jul 26, 2020).
  5. 自宅でできる米麹(米こうじ)の作り方. http://www.koji-za.jp/recipe/komekoji.php (accessed Jul 26, 2020).

Featured Picture: Courtesy to Food Craft Lab (https://flic.kr/p/wxPekt)

Karin ChoKarin Cho | Linkedin

SMF Weblog Author

Karin earned her B.A. in Biochemistry from Grinnell School, and through her time there, she was not sure the right way to merge her two passions for science and meals. After attending a number of IFT occasions and finishing a QA internship overseas, she determined to pursue a Grasp’s in Food Science and Know-how from Iowa State College. Her analysis includes the event of fats options. Rising up in a Chinese language-Japanese family, she developed a palate for tasting new, typically weird, meals. When she’s not studying about meals science, she enjoys watching science fiction motion pictures, taking walks in parks, and studying new recipes from the individuals she meets throughout her travels.

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