Koji-kin from Scratch, well sorta

How to make koji-kin for sake on your own.

One question I get fairly regularly is how to make koji-kin. Despite this I have failed to take the time to write up a good explanation for all of you. Well, no longer. In this article I will explain just what it takes and how to do it. Almost all you need to know is in my “Video Series and Instructions for making koji for sake” at: link. The only thing missing for making koji-kin from that source is that you need to sustain the last stage longer. That is, don’t spread out and cool the koji once it has completed its coverage of the rice. Rather, continue to monitor the koji so it does not get too warm or cold. It will start to show signs of a greenish yellow tint. This will progress into a darker greenish yellow color and begin to cover each grain. Once fully covered, carefully spread out the koji to cool. The green covering has lots of tiny spores that will come off so you’ll want to minimize disturbing it. After it has cooled, it needs to be dried so that other contaminates will not find it to be a nice home. Once FULLY dry, and I mean dry, you can place it in a shaker for later use.

The following picture is some koji-kin rice I have made. Some people will grind this into a powder but I’d use it as is.

Koji-kin rice
Koji-kin rice.

One way to use it is to put it into a shaker like the one in the following picture. It was purchased at a kitchen supply store and is often used for powdered sugar and the likes. It works well for koji-kin rice.

Koji-kin rice shaker.
Koji-kin rice shaker.

Using this shaker and koji-kin rice to shake over a piece of paper I get the pattern in the following picture.

Koji-kin from shaker.
Koji-kin from Shaker.

If you regularly make koji for your sake, you can, as needed, increase the batch size by 50% and after collecting and cooling the koji when ready, let the rest continue on as described above. This lowers the extra effort required for making your own koji-kin sense you were doing all most all the work needed already. Care must be taken to ensure the koji intended to continue on to koji-kin does not lose its warmth. Its smaller batch size will not hold its own generated heat as well as the larger batch.

Let us know if you make your own koji-kin and what your experience has been like!

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19 thoughts on “Koji-kin from Scratch, well sorta”

  1. Hey Will,

    Just want to start off saying how awesome it is that you keep responding to questions here for this long. All us homebrewers are very lucky!

    I have stored koji-kin spores (dark green) in the freezer for some months. Would there be useable still? I also have some dried ones in my fridge for some months, would these be safe to use? Is there any way to make sure?

    Second question, is it possible to ‘over inoculate’ your koji? I tend to go a little overboard to make sure the grains are all covered in the green spores.

    Lastly, are there different strains of koji spores? Is it possible that I have cultivated spores that are not optimal for making koji for sake? I have read things about different strains of koji spores but I cant find anything conclusive.

    Many thanks for any answers to any of the above!

    1. Thanks Aart.

      The only way to make sure the koji-kin you have created and stored are still useful is the try them out. If a full koji batch is too high a risk (the cost of throwing it all out) you can try to make a small batch, maybe just a cup of steamed rice. If it produces good koji you have your answer.

      It is possible to go overboard by applying to much koji-kin to the rice. That said, the consequences are not that bad. For good koji you want the mold to grow deep into the rice. Too much will have a tendency not to go as deep.

      There are different strains of koji-kin. Two large catagories are miso and sake. Of the strains useful for sake are koji-kin for Amazake (a sweet drink) and many variations for different types of sake. The one I sell is from GEM Cultures and is near the amazake end of the spectrum. I used to carry one specifically for Gingo sake but it was pretty expensive and did not sell well.


  2. You’re so awesome! I don’t believe I have read a single thing like that before. So great to find someone with some original thoughts on this topic. Really.. thank you for starting this up. This website is something that is needed on the internet, someone with a little originality!

  3. I wanted to express my appreciation for your exceptional work. This post has been incredibly helpful, and I’ve gained a lot of knowledge from it. Thank you for your dedication to producing high-quality content!

  4. Thank you for a great article!

    I have a question about dispersing koji-kin (or is it tane-koji?) on the steamed rice.
    The rice is supposed to be around 100F, which makes it warmer than the ambient temperature and thus creates an updraft, even if there’s no other source of air disturbance. In my experience, this was enough to not let the koji spores land on the rice, but instead all got drifted away.
    The only way I was successfully able to inoculate with spores was mixing the spores with heated rice flour and then sifting that mixture on top of the steamed rice. I’d still like to do it with your shaker approach. I’ve seen in some videos that this is how they do it at sake kuras. I guess it works for them because the koji moro’s ambient temperature is high and also it is humid.

    Any tips?

    Thank you.

    1. Hey Andy,

      I have not had any problem with the heat from the rice over coming the spores. My guess would be that I am letting the rice get colder than you are. Try letting the rice cool enough so the updrapht is no longer a problem.


  5. Native Son sounds like a capitalist. Do you really think that for how many years before companies came about, that people were not making their own koji kin just fine? Also that the reason large manufacturers buy their koji is because they need consistency in a product and also for convenience and efficiency? Help me out here, other people… I speak without so much as criticism as a DIY junkie perspective. I would rather do if myself if it can be done. I don’t want to be dependent upon a company from which I have to mail order koji. That costs money and creates dependence. If I can spend $x one time and perpetuate it with a little effort, I’m on board!

    1. Julie, I totally agree with you. Not just the fact of having to buy it, what happens if you can no longer get it? No more sake? No more Miso?

  6. Great guide, Will. I would, however, like to offer some terminology disambiguation:

    kome koji : Aspergillus oryzae mold specifically incubated on a rice substrate, used for making sake, miso, soy sauce, and other fermented products.

    koji kin : The spores of the aspergillus oryzae mold, used to inoculate kome koji cultures.

    tane koji: Kome koji that has been allowed to fully mature and produce spores.

  7. One reason for making it instead of buying it is the fun and curiosity in it. Another is the availability.

    I’m now in the process of making it myself.

    In Sandor-Katz’s book “The Art of Fermentation”, he recommends drying it in an oven at 45ºc. Personally to me it sounds like too high of a temp so I’m going for 30ºc.
    The info in his book is taken from another book and he refers to it: “Miso Production” / Shurtleff and Aoyagi. He mentions that they devote a whole chapter to the topic of Koji making.

    Good luck!

    1. Hey Yony, Those look like good and useful books. Love to hear about how things work out for you? What works best?

    1. This is not all there is to koji-kin. Koji in many applications is used mainly for the amylase but there are other compounds that have significant effects on sake, its taste and aroma.

      However, I assume you are responding to Native son. He has offered to give me a article with the issues and references when it is done. So I am waiting for that to respond. That said, home brewers do make there own and I never heard of an issue. As with yeast there are many different strains, there is an industry that makes it easier to get good ones with the desired characteristics which would be pretty much impossible for someone or a company that didn’t have significant resources to apply.

  8. The practice of trying to make your own kin in a home environment is
    NOT recommended as it is NOT safe!

    The problem lies in the extreme potential of cross contamination in a home environment.

    There’s a very good reason that ALL of the largest sake, miso & soy sauce manufacturers, in the world, who are also the largest consumers, don’t make their own spores or koji kin.
    It’s because it’s NOT SAFE!

    It is EXTREMELY specialized and a precise, exacting process that is carried out in clean room facilities by highly trained professionals.

    Also kin is so cheap, why risk it?

    1. Agreed my friend! I’d love to get my hands on yeasts, though! The people from Higuchi-Matsunosuke Shoten that sell great spores at great prices directly to anyone say that yeasts are now available to US customers with a brewing license through.

      1. Hey Nolan,
        I have heard something similar. I don’t know how you would get licensed though.

        Things are opening up,

  9. Great resource many thanks

    My prior batches I was fortunate enough to source pre made koji from a local miso producer. as producing Koji seem like an excessive investment for a first time brew. the other thing that got me was importing into NZ can be a hassle as shipping here is painfully slow. so if I was to purchase I though it would be more beneficial to maintain my own culture of koji kin.

    My key questions was what is the shelf life of the koji-kin and how do you best dry the end product to avoid undesirable contamination.


    1. Hey Rheuben,
      Koji-kin will last a long time though I don’t have any statistics on it. The spores naturally are waiting for a good environment to spring back to life.

      For most of us who don’t have any special equipment or dryers it is best to dry the koji in an area that is as undisturbed as possible. This is to avoid air movement carrying in contaminates. However, I have not seen many issues with this.

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