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Base koji for shoyu


Out of stock

(3 customer reviews)

This koji type is mainly meant for shoyu (soy sauce) making, but in our experience also a good all-rounder. If you do not know which koji to start with, this is the one to go for. Aavailable in 2 sizes: for 5 kg or 360 l. *Please note there are supply chain issues caused by Corona and the war in Ukraine. Delays are unknown at the moment*

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Koji is the fungus that can do anything: miso, soy sauce, shoyu, shio koji, amazake, black bean sauce, sake, doungjun, they all owe their amazing texture and flavor to the fungus Aspergillus oryzae. This all-rounder can also be used, for example, to perform cool experiments with the fermentation of meat or even dairy. Base koji for shoyu is the allrounder!

The instructions for making koji-kin yourself (the moldy rice that forms the basis for most of the above-mentioned foods) can be found below.

This koji type: base koji for shoyu

This koji type is mainly meant for shoyu (soy sauce) making, but in our experience also a good all-rounder. If you do not know which koji to start with, this is the one to go for.

Content base koji for shoyu

  • Available in 2 sizes: 15 grams, enough for 4-5 kg of dry koji-kin or grains/beans or 100 grams of pure spore for 360 liters of shoyu
  • Ingredients: riceflour *, Aspergillus Oryzae fungus (koji)
  • Storage instructions: best kept in the refrigerator for at least 6 months, more than a year in the freezer
  • Origin: Japan
  • Allergens: none
  • Soy-free

(*) ‘the amount of pure koji per kilo you need is very small, making it virtually impossible to dose properly, which is why all koji in small quantities is always’ diluted with potato flour or rice flour. Please note that the 360 l bag is pure koji and must be carefully mixed with at least 50% riceflour before use for proper dispersion.

Need larger amounts of koji-kin?

Contact us, and we will set you up.

How to make koji-kin


  • 300 g white rice, preferably not pre-cooked
  • ca 1 g (about ½ tsp) koji-kin starter culture (check your packaging, different types of koji have different strenghts)


  1. Rinse the rice until the rinse water remains clear. Let it drain for 15 minutes.
  2. Steam the rice for about 45 minutes. That works better than cooking it. Cooked rice quickly becomes wet and mushy when moldy, which prevents the fungus from doing its job properly. The rice should look glassy and feel soft and a little rubbery when you bite it.
  3. Let cool to room temperature.
  4. Mix the koji kin with the rice and let it ferment for 48 hours in a warm humid place 25 to 35 ˚C. Check regularly. Make sure to avoid condensation dripping onto the rice.
  5. During this period, mix a few times with a clean fork. The fungus needs oxigen.
  6. The rice will be completely covered in a white mold after fermentation. Though keep in mind that different koji variants have different colors.
  7. Stop as soon as you start to see green or yellow dots. These means the fungus changes into the spore forming phase. Use your nose (flowery, sweet) and tap the fermentation vessel to see if no (or few) spores have been formed when in doubt.

Buying base koji for shoyu?

Order your base koji for shoyu at startercultures.eu, the European webshop for all your fermentation needs. By Meneer Wateetons, renowned Dutch fermentation expert and author. Order on weekdays before  3 pm and we’ll ship the same day.  Questions on the usage of base koji for shoyu? Ask them in our chat, we’re here to help!

Online English spoken workshop ‘how to make your own miso’Fermentation workshops

During this online master class, Dutch foodwriter and fermentation expert ‘Meneer Wateetons’ will teach you how to make your own miso. Thanks to a special form of fermentation, two very modest and rather boring ingredients come together to form one of the most beautiful, complex substances on earth. Mister Wateetons tells you exactly how that fermentation works and what you need for it, how you can make miso at home from now on, how you can speed up the process of making miso, how you can vary endlessly on these two basic ingredients and what kind of cool things you can do with miso. Click here for more info.

3 reviews for Base koji for shoyu

  1. Gregor (verified owner)

    Nice mold, not finished yet.

    (0) (0)
  2. Anonymous (verified owner)

    (0) (0)
  3. Richard (verified owner)

    (0) (0)

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