Soy Sauce Koji Spores

(5 customer reviews)

From: 6,00

The amount refers to how much wet substrate can be inoculated. For more info, click here.


This is a strain for soy sauce with strong protease activity. It is meant for long-term, dark shoyus. If you want to make a light shoyu, A. Sojae is better suited.

According to the producers, this strain takes three days to fully grow on the substrate (soy beans and wheat). In my experience, the koji is finished after 40 hours.

We have a tutorial on how to make soy sauce, check it out here if you haven’t seen it yet.

Weight1.05 g

For 5 kg, For 50 kg, For 200 kg

5 reviews for Soy Sauce Koji Spores

  1. Alex (verified owner)

    This grows very, very quickly, as the page notes. Be prepared to check on it every 8-12h. It needs frequent supervision so it does not sporulate or overheat. If you can do that, it grows very well.

  2. Casper (verified owner)

    My compliments on the great service! Used 1 bag to inoculate about 5 kilo’s of soy + wheat substrate for soy sauce making. Read about the high-risk of overheating for this strain, and decided to take the easier route of fermenting it at room temperature for a longer time, since I don’t have a precise temperature-controlled fermentation room and would have otherwise used the oven. Mycelium growth was clearly visible within 12 hours, but otherwise growth was pretty erratic, sometimes heating up to 37 degrees, sometimes remaining at room temperature for a long time. First signs of sporulation were visible after 6 days, and then stopped by steeping in brine. Any comments are welcome! Overall it was a great experience and brought a lovely aroma into the house :-)

  3. David A (verified owner)

    Perfect for making soy sauce! The spores are of superb quality and grow very reliably, yielding full coverage of the substrate. As noted in the tutorial, this koji grows vigorously and produces much more heat than ‘usual’ koji, so be sure to stick a thermometer right into it and monitor it frequently. And I can recommend to make the mat very thin to help the heat dissipate.

  4. Enrico Bufarini (verified owner)

    Great product like all the oder spores that I bought. I follow Viktor’s instructions and they work very well. I used a redpine wood tray and incubated the Koji at 30 C for 2 days and the smell of mixed pine wood and Koji was awesome.
    I’m very happy with the shop: professional staff, very good products and fast dispatch.

  5. Bernd Simons

    We used one bag for ca. 12 kg and mixed it with starch before we put it on our wheat and beans mixture. After five days we had lot´s of koji spores and a fine fermentation, temperaturs below 30° celsius. Now after six weeks in the brine we have a brown very good looking, and salty raw soy sauce, looking forward what to come! :-)

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