Making Amazake at Home

Apr 26 2013 by Sjon Welters  |  28 comments

Koji! What is it for and how do I use it?

We now offer our own Certified Organic Short Term, Long Term and Amazake Koji. With the launching of these products I thought it would be appropriate to write a little bit about what koji is, what we can use it for, and how it works.

What is Koji you ask? It is a filamentous fungus that is grown on rice. It’s Latin name is Aspergillus oryzae. It is used in Asian cuisine to ferment soybeans and grains to produce foods such as miso, soy sauce, amazake, sake and other alcoholic beverages.  There are hundreds of different stains of koji used for the different varieties of miso.Fresh koji

To make Amazake, Koji works as an enzyme to start the fermentation process by breaking down the complex carbohydrates into simple sugars. It requires specific temperatures for it to being this process and can’t be heated over 140 F. At this temperature it kills the fungus and will stop fermenting and increase the risk of spoilage. In the miso making process Koji breaks down the proteins at room temperature, with salt being used to control this process.

In following posts I will describe how to make miso and share some recipes using miso including dressings, soups, sauces, slowly cooked vegetable dishes and more! Also, when you order Koji from us we will add the instructions on how to make Amazake or Miso.

Now, onto how to make Amazake!




Pot with lid
Double boiler or large pot with lid
Probe thermometer
Flame diffusers
Blender (optional)
Mason jars

5 cups organic rice (brown or white) (soak brown rice for 6 hours or overnight)
7 cups water
pinch of unrefined seasalt
1 cup Rhapsody Amazake Koji

Bring water and rice to a boil, add salt and cover. Let simmer for 50 minutes.

Let rice cool down to 135°F. Add koji and stir well. Cover.

Insert pot with koji and rice mixture in a pot with water (double boiler style) that’s between 135°F and 140°F. Use a thermometer to be able to control the fermentation process closely. Slip one or more flame diffusers and/or a skillet under the double boiler, to maintain the water bath at the right temperature.

Check temperature of water bath regularly in the beginning to get the temperature right. You can adjust the temperature by the number of flame diffusers. The temperature should range between 135°F and 140°F. If it goes over 140°F it will kill the Koji and stop the fermentation process and if it goes below 135°F the fermentation will stop and there is a higher risk of spoilage.

Let sit overnight or for about 8-12 hours at that critical temperature. Stir occasionally.

When fermentation is done and the rice mixture smells nice and tastes sweet your amazake is ready. Bring to a boil to stop the fermentation process and prevent souring. Simmer for 10 minutes while stirring regularly to prevent burning it. Blend until smooth if desired and pour in a mason jar (rinse the jar first with hot water to prevent the glass from cracking) while boiling hot.

Unopened the amazake will last for months refrigerated.

Note: To make the amazake sweeter use 50-100% more koji.

Variations: Use oats, roasted millet, or any other grain to get different types of amazake.

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28 comments on ... Making Amazake at Home

  1. Laura Wells says:

    I put amazake in quart jars with lids, immerse in a big pot and use a sous vide to keep the water at 135 degrees. It works perfectly.

    • A great way of making it. Additionally, after the amazake is done, you can just heat the water up to 180-212F and stop the fermentation to prevent souring and pasteurize it. No need to fill it off in jars anymore. So much simpler! Just don’t put the lids on tight yet to allow air to escape. Otherwise the jar(s) might explode.

    • Lacey says:

      Thanks, Laura. I’m so interested in trying this with the sous vide. Can you tell me more details, please? Concerned with lid, explosions, and timing.

  2. Shaky says:

    What do you think about using the “keep warm” function of a Slow cooker or rice cooker? I mean for the second step. Has anyone tried?

  3. Rick says:

    Following up on Elysha’s comment back in May that as long as you boil the soured amazake it is fine to eat … thanks for that, but why is that ok? We’re always warned to not eat food that has gone sour. I’m guessing boiling it kills the potentially harmful bacteria? Does that only work for rice, or for all grains, or for other foods as well? Not vegetables or beans, I imagine…?

    • Souring is not necessarily bad. Think of sourdough for sourdough bread, yogurt, sauerkraut, to name just a few of hundreds of traditional soured foods worldwide. Boiling, baking, or other 180F+ heating processes do kill organisms responsible for the souring, but makes them edible without any unpleasant side effects. Soured beans and vegetables can be a little tricky; it all depends on the kind of organisms involved and what kind of souring is taking place. Soured grains in general are traditionally used for all kinds of dishes.

  4. Rick says:

    A few months later …. I want to mention that a Hamilton Beach slow cooker has just come onto the market that is pretty decent for making amazake. It’s called the Temp Tracker and you can actually program it to stay at a certain temperature. It’s done via a temperature sensor that you put right into the mixture via a slit at the rim of the cooker. I’ve made two batches of amazake so far and am getting the hang of it. I should mention that I called the manufacturer and they don’t recommend using this with rice as they can’t guarantee a uniform temperature through the mixture, but it works ok for me. I’ve had a tad of souring but I have a feeling that could be remedied by stirring occasionally which I haven’t been doing rigorously.

  5. Motoko Oulman says:

    Check Amazon. We bought one made by Nakasa in Japan from Amazon and like it very much. However, the instruction is written only in Japanese, though it is rather simple. So you might need someone to help you, unless you read Japanese.

  6. Rick says:

    It sure is too bad that there is no kitchen appliance available in the US that is specifically for the making of amazake. I guess it’s stating the obvious to say that there just aren’t enough people making it (or even know about it!) to make it worthwhile for a manufacturer, which is too bad. Maybe someday a manufacturer of yogurt makers will design one with a low setting for yogurt and a high setting for amazake (and thus capture the market of all 17 of us in the country who make amazake).

  7. Rick says:

    I phoned EuroCuisine and they confirm that the average temperature inside the unit is 110-115 degrees. So this wouldn’t be a good utensil to use for amazake.

  8. Rick says:

    I made amazake for the first time last night, and decided to try the Euro Cuisine YM80 Yogurt Maker with a 7-cup glass bowl as mentioned in a comment above from Sept. 2016. I left it overnight, for eight hours. Result as of the next morning: the temperature is too low and it soured. I inserted a digital thermometer into the mixture just now and it was registered 122 degrees, which is really too low, so I’m not surprised that it soured. Interestingly, it is also quite sweet so clearly the koji worked, but as an additional bacterial process it just went sour as you would expect to happen if you left 7 cups of rice overnight at 120 degrees. So I guess I have a sweet and sour amazake. Not sure exactly whether I want to drink it but just for the experience I might. I don’t think 8-hour sour rice is bad for you, just not particularly pleasant to eat or drink.

    I wonder if since Sept. 2016 the manufacturers have lowered the temperature the device achieves. Maybe I’ll phone the manufacturer and ask them about that.

    btw, I used the proportions above (1 cup koji with 5 cups rice) and it’s almost too sweet. Next time I make it — probably with a rice cooker as mentioned on other web sites- I’ll use much less koji.

    • My experience is that when you go below 135F there is a tendency for souring, especially on the surface. At 130 F the risk is even higher. Yogurt makers are too low in temperature, as the yogurt culture likes 110-115F during fermentation. As long as you boil the soured amazake it is fine to eat. Think of it more as buttermilk-like then, the expectation is different and you might actually like it like that.

  9. Reuben Romero says:

    I make Amazake in my electric crockpot. The crockpot is too hot on its “Low” setting, so I spliced a cheap rotary dimmer switch from Home Depot into an extension cord. Then I experimented with dimmer switch settings till I get 140F.

  10. Katie says:

    After it’s made can I culture more from the leftover brine, or will I need to have koji on hand for every batch that I make?

    • Sjon Welters says:

      Every time you make amazake you need new koji, since every batch of amazake you have to cook to de-activate the enzymes to stop it from turning into rice vinegar.

  11. Louise Kavadlo says:

    I make amazake. I use 2C.wholegrin rice, 1C.Koji, 6C.water. I simmer rice, cool till comfortable, add Koji, cover pot, set in oven. Sit for 8 hours till “sweet.” Blenderize and chill.

  12. Polly says:

    Wow, what a terrific lot of information you have on your site. Thank you! I’m in Australia so can’t buy your koji, but really appreciate all you are sharing.

    I have a couple of questions. First, your recipe uses a different ratio of koji to rice than anywhere else I’ve read. Is your koji different? Hope you can explain how you are able to use so much less koji. Your recipe would be great for me as I can only occasionally find koji rice and it’s always very expensive.

    Secondly, I don’t have a rice cooker but do have a circulator, so will set up a big water bath at temperature in which to place the it with the amazake-to-be. So, how much air does the enzyme need to work? How tightly may I lid it ?

    Thanks again, Polly

    • You’d use more koji if you want the process to go faster and more if you want it to be sweeter. If you take your time less koji is required.

      With less koji you let it ferment for 12 – 16 hours at 135F – 140F (57-60C) to get the best results.
      Stirring it frequently and blending the rice and koji together will reduce the time significantly.

      Air is not really an issue as the enzymes are submerged in the slurry. A tight lid would actually be good as it prevent contamination and keeps the temperature steady. Put a towel on top of the lid to keep the heat in. A thermometer in the water bath will help you keep an eye on the temperature. I’d suggest you keep the water as close to 140F (60C) as you can.

  13. N. Butler says:

    I have made amazake off and on for many years, and found that the easiest, most reliable method is to use a Euro Cuisine YM80 Yogurt Maker, which comes with small jars that can be removed. Rather than the jars, I use a Pyrex Storage Plus 7-Cup Round Glass Food Storage Dish, and put the grain and koji into it. I had reservations about whether this would work because the temperatures for making yogurt are lower than those for amazake. I originally purchased the yogurt maker with the intention of making dairy-free yogurt, but did not care for the results, but this may have had something to do with the Euro Cuisine YM80 yogurt maker: many of the people who reviewed this item on Amazon complained that it was too hot. Whatever the case, making amazake with it has been problem-free!

    • Sarah says:

      Would you please tell me the steps you follow to make the Amazake your way? How do they differ from the steps in the above article? 🙂

      • It would work as long as the temperature is high enough to prevent the slurry to go sour. Between 130F (54C) and 140F (60C) is optimal. Below 130F invites souring and above 140F kills the process.

  14. Donald G. Wallace says:

    Why is amazake made at 140 deg. F (60 deg. C), but manufacture of the koji-jin starter (addition of Aspergillus spores to cooled cooked rice) is limited to 35-40 deg. C? How can the koji fungus survive the higher temperature during amazake preparation? Thank you.

    • Sjon Welters says:

      My understanding of the process is as follows. There are two processes: the growth of the mycelium by the Aspergillus spores on the cooked rice and the production of enzymes during the mycelium growth. The spores can’t survive above around 113F, but the enzymes can handle temperatures as high as 140F (60C). In other words: the spores and enzymes have different temperature tolerances and different functions.

      I hope that answered your question.

      • Barry says:

        Indeed, the amylase actually needs a higher temperature to get a good metabolizing activity going on, and if the temperature of the freshly cooked rice falls too low during the amazake making process, bacteria will start to grow, making it go sour. That doesn’t happen when they make Koji because they make koji rice by adding koji spores to sufficiently sterilized rice and let that grow out until it is fully colonized. If you would then proceed to let it sporulate you would have obtained tane-koji, spore starter. But to do that, you would have to know about sterile procedures, have the experience and knowledge about the aspergillus’ preferences, and some expensive equipment. And a good tolerance for cheesy smells, as growing koji smells like cheesefeet.

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