Making DIY Miso from Soy Beans – A step-by-step guide | Home, DIY & Stuff

Making DIY Miso from Soy Beans – A step-by-step guide

Raw Soy Beans

Healthy, raw soy beans.

Miso paste is a unique, traditional and extremely important ingredient in many Japanese foods.  Miso making has been commercialized and is usually made on massive scale for supermarkets and everyday consumption in Japan.  We at Home, DIY & Stuff however, wanted to step back to the more traditional technique of home DIY Miso making.

The first comment that needs to be said about DIY Miso making is that like wine or cheese making. 

It is more of an art to develop tastes and textures, than a science, so feel free to experiment a little even if you are following our step-by-step guide for your own purposes.

An extremely wide variety of Miso paste types and derivatives exist depending on the base ingredients used.  The preparation, fermentation, fermentation culture and timing employed also has a large impact on the taste, texture and look of the matured paste.  More information on the wide varieties of Miso available and regional production techniques used are available from Wikipedia if you are interested.

Earlier we announced that we had both received a specific Miso making kit from  a company called “Komego” in Fukui, Japan and that we were ready to go ahead and make the Miso paste.  This kit contained all the ingredients for making a Soy bean based Miso (ie: mame miso).  Since we are chasing a deep, rich tasting Miso after maturity, this specific project is lengthy and requires a total fermentation period of approximately 10-11 months.  However, shorter or longer preparation is also possible, depending on the desired taste.

Be pre-warned.  Miso contains a large amount of salt, despite being widely known as a “healthy food”.


Contents of DIY Miso making kit.

Contents of DYI Miso kit. (Click to enlarge)

Required Items for this Project

The items and ingredients needed for this Soy Bean Miso project are:

1. Items contained in the DIY Miso Kit

2. Other additional items needed

  • Large saucepan(s) / Pressure cooker (ie: cooking requires 3-5 hours with normal saucepans vs only 20 minutes using a pressure cooker!)
  • Various small and large mixing bowl(s)  (ie: large portions can be separated into smaller bowls for easier mixing and convenience).
  • Measuring cup
  • Kitchen scale
  • Rolling pin, or wooden pounding hammer
  • Plastic kitchen bags (optional)
  • 2kg stone or other weight.
  • Approx. 50cm of plastic kitchen wrap
  • 2-4 sheets of clean newspaper or butchers paper
  • Approx 2-3m of string or light rope.


Step 1 – Wash and Soak Soy Beans

DIY Miso soy beans soakingSoy Bean WashingAll 1.3 kilograms of dry soy beans were poured into a large bowl and washed lightly with fresh running water. This released the bean powder that accumulated on the surface of the beans.  Just a light wash was sufficient.  The runoff water was still slightly yellowish when we had finished.

To make things more manageable and knowing that the beans would swell considerably, we separated them into two batches.

The beans were then left to soak for 24 hours.

Although initially almost round when dry, the soy beans became a proper bean shape of approximately 1.25mm (half inch) in length following soaking.


Step 2 – Cooking the Soy Beans

Two options were available for cooking depending on whether we used a saucepan, or a pressure cooker.

Soy beans needed cooking for 3-5 hours on a stove in a saucepan, or only 20 minutes in a pressure cooker.  We opted for the pressure cooker option to save time and gas!

DIY Miso - Pressure cooking soy beans

The beans needed to be cooked so they were soft enough so they squashed just a little between thumb and forefinger with firm, but comfortable pressure.  We also knew they were ready when the halves slid apart relatively easily while squashing (ie: therefore not too over cooked and slimy, but also not too hard).

We kept the liquid that the beans were cooked in, as this was used later for mixing with the Kōji and salt (step 5).


Step 3 – Preparing Salt Batches

While waiting for the soy beans to cook, we separated the salt into three separate batches.  Each portion has a separate purpose.  We used kitchen scales to measured out a portion of:

– 5 g of salt

– 65 g of salt

– 630 g of salt

DIY Miso - Measureing out salt

Step 4 – Preparing the Yeast (Kōji culture mix)

DIY Miso - Kōji fermentation culture

The three packs of yeast (Kōji fermentation culture) were emptied evenly into two (for convenience) large mixing bowls.  (ie: We tried one bowl to start, but mixing was far more manageable in smaller batch sizes.)

The yeast was supplied as dried, compacted blocks that required refrigeration to maintain the vitality of the culture.  It were lightly crumbled apart in the bowl(s).

The 630 g portion of salt was lightly and evenly mixed into the yeast culture.

DIY Miso - Kōji fermentation culture and saltMixing Kōji and salt






Step 5 – Mix Yeast and salt with the water previously used for cooking soy beans.

After the soy beans were cooked sufficiently, we poured the resulting yellow colored water off the top of the beans into a measuring cup.

We required 500mL in total. It was placed into a separate bowl.

The 65 g portion of salt was then poured into the 500mL of cooking water and stirred with a whisk until dissolved.

The water was then allowed to cool to approximately room temperature.  (Caution: Water that is too hot may kill the fermentation culture!)

DIY Miso - Soy bean water DIY Miso - Water from cooking soy beans

The yellow soy bean cooking water was then mixed in even portions into bowls with the yeast & salt mix from the previous step.

All contents of the mixing bowls were well churned over by hand for several minutes.  This ensured we had an even distribution of all ingredients throughout the entire (thus far) combined ingredients.


Step 6 – Crushing Soy Beans

Mashing soy beansThe cooked Soy beans were cooled a little and drained of water (ie: ensuring we had kept enough water left over for what was needed in the previous step!).

The soy beans were then poured from the pressure cooker into a plastic kitchen bag.  We removed the air from the bag and then tied a knot at the top so the beans could not spill out during the crushing process.

We took a Japanese rolling pin and crushed the beans in the bag until they ended up having a pasty consistency.  We allowed some “chunks” to remain, as we thought this might add to the final matured texture of the Miso. (Here again, due to the large volume of beans, we ended up separating the cooked soy beans into four separate smaller batches to make this pasting process a little more manageable. The photos show one batch only.)


Step 7 – Mix all ingredients together.

The mashed soy bean paste from step 6 and the mixed salt/yeast culture/cooking water from steps 4 and 5 were then all combined and mixed well to ensure even consistency throughout the crumbly paste.

DIY Miso - Combining all contents

DIY Miso - Mixing all ingredients

Step 8 – Placing paste into storage container

DIY Miso - Patting paste into balls.Once the entire mixture was combined, the paste was patted into fist sized balls.

Using the 10L storage bucket from the kit (or chosen container), the balls of paste were then thrown into the base of the bucket so they would splat flat.  This (apparently) helped the aeration of the paste for a final time as it began the fermentation stage.  Multiple balls (approximately 10-12)  were made out of the paste in order to empty the mixing bowls completely.  Each was  thrown into the gathering heap of fist sized balls in the storage container.

Filling miso fermentation bucketFor our kit and with the amount of soy beans and other ingredients used, the 10 L bucket ended up approximately three quarters full.

Once all the paste balls were transferred to the storage bucket, the top was firmly patted and pressed down to remove most of the air from between the paste balls and to form a level surface across the top of the container.


Step 9 – Application of (more) salt

DIY Miso - Sprinkle salt around the edge of the miso paste.Using the remaining 5g portion of salt that was prepared in the beginning, a sprinkled line of salt was made all around the outer edge of the paste.




Step 10 – Compression and storage

DIY Miso - Compression lidThe top surface of the paste was then lined with plastic kitchen wrap, such that the wrap climbed the walls of the bucket to make a very loose, non-airtight seal.

The supplied circular wooden lid was placed on top of the plastic, followed by a 2 kg weight.  The weight adds compression to the paste mass below during fermentation.

Anything heavy and of similar size to the wooden lid was ok for this purpose. We struggled to find anything clean and suitable for this, so we used a freezer container filled with water and a heavy, overturned clay dish.  (ie: the bucket did not require total airtight sealing afterwards, so it didn’t matter if he weight protruded from the top of the container.)

DIY Miso - 2kg weight placed on top of paste.eight for compression

Step 11 – Covering the container

Finally, the whole container was topped with newspaper, which was loosely tied around the bucket.   The idea was not to seal the bucket’s contents entirely, but instead to provide a little further protection from dust, insects and external moisture.  The plastic top of the provided bucket was not required.

The binding does not need to be very permanent as the contents will need mixing and attention on a monthly basis here-after until maturation.DIY Miso - Wrapping


Step 12 – Storing the container for fermentation to take place

The container was then stored in a cool, dark place where any light odor that may be produced later does not become a concern.  We also ensured that we chose a place away from any possible insects, rodents and other animal which might otherwise make a tasty morsel of our fermenting Miso paste.

The temperature around the container will vary greatly between the current chilly late Winter season and the later peak Summer season.  This variation however is all part of the fermentation process and adds to development of taste.  Constant temperatures are not required.


Steps that are still required include mixing and skimming of any mold growth that develops.  More to come soon (see updates below).

***** Update – Half Year Miso Re-Mix *****

DIY Miso Paste made from Soy Beans is mixed at six month milestone.

(Update — 2015, June 28 – Half Year Re-mix)
See our half year Miso paste project update notes as we re-mix the ingredients after the initial cool period of Winter fermentation.

***** Update – Mission Complete! *****

DIY Japanese Miso Cracker Dip

(Update — 2015, December 2 – Mission Complete! )
Mission complete! See the end result of our home DIY Miso paste fermentation project. It was a complete success and we made extremely tasty Japanese miso.

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