How to dilute the spores

The spores you can buy from this shop are delivered undiluted. They are pure spores – a really minuscule amount of spores is needed to inoculate 5 kilograms of steamed grains.

If the spores are not diluted, it can be hard to spread them evenly over your grains. In order to make the spores easier to handle, I really recommend diluting them with toasted flour.

 How to dilute the spores

You will need a kitchen scale, a bowl, flour (can be wheat or rice flour), a pan and of course the spores.


Put 29 g of flour into the bowl. It can be 30 g, as you are probably going to lose some flour in the process.


Put the flour into the pan and toast it until it gets light brown. The toasting is important to kill off any other mold spores that me be present in the flour. Be aware that the browning can happen very quickly! I have burnt the flour more often than once. Move the flour around a lot, to avoid burning it.


This flour is brown enough, in fact it is browner than I wanted it to be, but it is still OK.


Let it cool down for some time.


Once the flour is cool, add the spores.


Mix the flour and the spores.The mixture is now ready for usage. You can either start a batch right away, or you can store the mixture for later use.


In this case, I wanted to use all of the mixture right away. If you want to start, say, 1 kg of steamed rice, simply use a fifth of your mixture. This should now amount to about 6 g.

The dilution of the spores serves two purposes: you can divide the spores more easily if you want to make less than 5 kg of Koji, and also you can spread them more easily. If I just poured the pure spores into my tea-strainer, they’d probably all end up in one spot. Now that they are diluted, I can spread them very evenly.


I find that a tea strainer works well for spreading the spores. In this case I was making soy sauce, if you are wondering :)


I hope this article was of help to you :) Wish you happy fermenting!

This Post Has 2 Comments

  1. Hello Viktor,

    How do you best keep the spores for later use, can they be frozen or example?

    1. Freezing is not good for the spores. They are best stored in a cool, dark and dry place. Slightly below room-temperature is good. They will stay viable for at least a year. After that, you can just use a bit more spores to make up for any lost vitality.

Leave a Reply