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Make miso

Not many people make miso at home because it’s a very lengthy process and requires some experience. Nevertheless we will try to explain how to make miso at home.

Ingredients for home made miso

To make miso you need the following ingredients:
  • 400 g whole soybeans
  • 600 ml water
  • 150 g salt
  • 300 g dried rice koji (rice fermented with special moulds, this can be bought are also made at home)

Miso production process

All utensils which you use for the production of miso should be clean and preferably be rinsed with boiling water. These are the steps to make miso at home:
  • Soaking the soybeans - Soak the soybeans during 3 hours in the water. By that time the soybeans should have doubled in size.

  • Cooking the soybeans - Put the soaked beans with the soaking water in a pressure cooker and cook at max pressure during 40 minutes. The soybeans should be soft. Open the pressure cooker and drain the beans in a colander, making sure to recover the soaking water.If you don't have a pressure cooker you will need to boil for about 3 to 4 hours to obtain soft soybeans.

  • Mixing the soybeans - When the beans are still hot, use a potato masher to puree the beans until about one third of the soybeans is still whole. Allow he beans to cool down to 35-40°C. If temperature is too high the koji culture could become inactive.

  • Making miso paste - Take 200 ml of the soaking water (add more water if you don’t have enough of it) and dissolve the salt (except for 2 teaspoon salt which you need in the following step). Add this liquid slowly to the soybeans while mixing stirring continuously. Crumble the koji into the miso mixture and with your clean hands mix until you obtain a smooth mixture.

  • Preparation of miso container - As a fermentation vat use a glazed ceramic cylindrical container of about 5 kg. Make sure that the ceramic container is suitable for food preparations. Rub the inside of the container with 1 teaspoon of salt and add the miso mixture. Level the miso surface and sprinkle 1 teaspoon of salt, this to prevent unwanted moulds and bacteria from spoiling the surface which is in contact with the air. Cover the miso with a round piece of kitchen paper and press it firmly on the miso. Top with a round wooden lid that just fits in the container and some weights (about 3 kg, well washed stones). Cover the container with wrapping paper and tie in place with a string or rubber. Repeat all steps as before to make more batches in the following days and add them to the container (first removing lid and rubbing the inside of the container with about 1 teaspoon salt) until the container is about 80% full.

  • Miso fermentation - The fermentation will start immediately. The container should be place in a clean room with moderate temperatures (15°C – 25°C). The miso will be ready after 6 to 12 months fermentation. During the fermentation some liquid (=tamari) will rice to the surface. If no liquid tamari is seen on the surface then the pressing weight must be increased.
    Each time you want to inspect the fermentation process you will loose quality, so don’t do it when not necessary and not more frequently then once every 2 months. This miso can be kept in the container for a few years.

Traditional Japanese miso production

In Japan miso was traditionally produced in small miso shops. Each miso shop used its own unique process and has its own secrets. Before one can make miso he needs to be educated by a miso master during several years. Typical for these miso shops is that the soybeans are cooked in containers on open fires, that miso is fermented in wooden vats and that no motorized equipment is used. These days there’s a lot of competition from big modern miso factories. Due to optimized fermentation conditions the miso is ready after months instead of years. In Japan most miso produced will end up as miso soup.



I've just recently discovered this great website.
I've noticed that you give very detailed descriptions of how to make miso, however, I can't seem to find any information about where to buy koji.

Is it possible to find it in Europe?

thank you in advance.
Lene - 23/10/2013


This Dutch company sells koji:
In the US there is Gemcultures.
Rob - 23/10/2013


Dear Rob
thank you very much.
I'll look into it.
Lene - 23/10/2013


I was wondering... Is commercial Miso cooked at the end of the process in order to stop the fermentation, or would it still have live Aspergillus oryzae in it?
Could I use old miso as a fermentation starter for a new batch (I cannot find Koji where I live?
thank you ever so much
Angel - 17/03/2014


Natural miso is a living product containing live bacteria. However, most commercial miso that is packed in glass jars or plastic bags is pasteurized. Even if you can find unpasteurized miso it will not be a reliable source for the Aspergillus oryzae spores. Koji contains millions of live Aspergillus oryzae spores. The main purpose of Aspergillus oryzae is the production of enzymes that will later digest the soybeans. After you add the koji to the soybeans other ingredients are added such as salt which will kill the mold. Other yeasts and bacteria that can withstand the salt will then grow and enhance the aroma and taste of the miso.

Rob - 18/03/2014

Where to get koji

You can get them in any Chinese / Asian supermarket. Chinese ferments sticky rice slightly and they use it as desserts. I think they are also called rice leaven in Chinese supermarkets.
Flora - 08/04/2014

Can I use Miso that I have made to make a new batch

Is it possible to use Miso once prepared to make a new batch the next year or do I have to buy the seed culture every year. Seed culture is quite expensive to get here.
Joe Harris - 03/05/2014

2 year old barley miso that's dried out a little...

Hi there!
I've made a batch of barley miso that's been ageing for a couple years. I removed a little after the first year, and promptly forgot the rest in it's ceramic vat. After having another look it's now dried out a little. Still seems fine and tasty, but any thoughts on re-hydrating older miso batches?
Justin M - 28/12/2014

2 year old barley miso that's dried out a little...

I am not a barley miso maker, but I think you can use it as long as it tastes and smells nice. You should only rehydrate that portion that you want to use for direct consumption. Adding water to the whole batch might cause spoilage.
Rob - 28/12/2014


I've been searching for koji-kin or koji-rice but I can't find any in Mexico. Is there any way to replace it or to make the latter at home without koji-kin?
Thank you very much in advance :)
Aura - 19/01/2015

Microbiology Major

Unfortunately not. Koji needs the domesticated Aspergillus strains to be safely made. Here is a more friendly site for koji explanation than most of the articles I have read.
Thomas - 16/04/2015

Making miso

Is there an easier recipe
noightysia - 21/05/2015

get koji here

you can buy koji on Ebay
iam420express - 05/07/2015

koji safety

as i read about these koji spores, i become more hesitant on using them. if you ferments them more than 3 days, they start producing toxins and can you 100% guarantee how any company handles it? also, as i understand, koji can't be killed because these are spores and just because other people are using them, doesn't mean they're safe, like cigarettes. does any one know is other bacteria can ferment soy?
soya - 05/08/2015


Aspergillus oryzae has been verified by the FDA as GRAS (generally reccognized as safe).
Dan - 26/08/2015

Miso Fermentation

Thank you for the great information that you provide in this website! I have a question regarding MISO fermentation. I am using 5 kilograms transparent glass containers. Should I keep the containers without any light, in other words in complete darkness? Or some moderate light is necessary? Again thanks in advance for your reply and help.
Martin Braunstein - 12/09/2015

which kind of soy bean

I want to make miso and I am wondering which kind of soybean I should buy, White or Green? Which will be the difference¿
buensake - 01/12/2015


HI, thanks for this site it's very informative. I've got ground Angkak. Does anyone here know if it works well as a koji replacement? The english subtitle says red koji rice
Maria - 31/08/2016

Miso making

I read on the soy info center that red Koji can be used to make Miso but I have not tried, and it may have a slightly different color.
Kodo - 13/09/2016

Adding live miso to pastuerised mido.

I purchased a tub of pasterised myso before i realised it has no living culture in it. Boo! I have since bought a live miso which i love but its very expensive...if i mixed the pastuerised one in with the live one would the culture spread in it?
Nabiki - 18/10/2016

make miso

i have 3kg of koji and plan to make miso using 4kg of beans but i am not sure about the amount of salt to use can anyone advise me about this
bill - 11/02/2017


I like these website, very useful information is given for making miso or miso products miso soup is healthy as it is made by soyabean in which protein content is high... Love the site..
Mahesh Badgujar - 09/07/2017

Aspergillus Oryzae

Can I capture aspergillus oryzae by letting rice ferment naturally?
Joice Maiara - 11/09/2017

Error found

Miso making is not a fermentation, but a phenomenon that soybean protein turns into amino acid due to the chemical reaction of enzyme produced by Bacillus. Since bacteria die at the time when salt is added, there is no fermentation after soybeans are charged.
Kojiro Oka - 01/02/2019

How to make miso without koji?

How to make miso without koji?
Jun - 25/03/2019

transferring new miso

i have a gallon and half of miso that ive had fermenting about a month now . i have it in a really big glass bowl with a glass plate over it . i now want to know if i can transfer it to a large ceramic canister i have ? or will this destroy the miso process? thanks

carol mayo - 23/04/2019

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