After translating the last two posts with Marie Chiba's recommendations for mixing and matching sake at home, I really wanted to try the doburoku (traditional home brew style sake) + soda = "dobusoda"... but with the limited range of sake available in Switzerland my chances of getting hold of some doburoku were roughly zero.

I think the only time I've seen it in Europe was last year's Kura Master tasting.

Home brewing (anything over 1%) is illegal in Japan, so there's no strong home brew community like there is for beer in other countries. However, it's perfectly legal in Germany and Japanese programmer Yoshito Maeoka started brewing his own doburoku at home while working there. This is a summary of his instructions from the Oryzae Wonderland site, which also covers making kōji rice, miso, amazake, mirin, shio-kōji, soy sauce, nattō and kefir.

The original article has plenty of photos and guide times, so have a look if you want to see what the process should look like.

[Just noticed he has an article on cacao miso. Relevant to all my interests...]


REMINDER: Brewing anything over 1% alcohol is illegal in Japan without a license. Please check your country’s regulations.

Makes 700 ml

Ingredients

  • 500 g table rice
  • 150 g fresh (nama) rice kōji
  • 650 ml water
  • 100 ml warm water (to dissolve bread yeast)
  • 0.75 g dried or 1.5 g fresh organic bread yeast

Equipment

  • Pan for steaming rice (or pressure cooker)
  • Stainless steel steamer insert
  • Container to dissolve bread yeast
  • Plastic food storage box or other container to cool steamed rice
  • Rice paddle
  • Colander
  • 1.5 L or larger sterilised container for brewing (3 L if using a ziplock bag)
  • Large sterilised spoon or similar for stirring
  • Sterilised container to store the brewed sake

Notes

  • Until around day eight, taste the moromi every day to see how the flavour changes. The rice kōji contains carbonic acid, which changes in strength over each day of the ferment. You can feel it on the tip of your tongue.
  • Any moromi stuck to the mouth of the container can attract unwanted microorganisms so make sure to wipe it up with kitchen paper.
  • There is a huge range of bread yeast on sale: dried, live and from different producers. Maeoka says he tried a few different types, and it does influence the aroma of the moromi.
  • Based on Maeoka's personal experimentation keeping the ferment at room temperature (around 20°C) doesn’t necessarily produce bad sake, but bread yeast will also work at low temperatures. Even brewing in Germany during the summer, the sake didn’t go off or spoil. However, it’s easier for it to become contaminated in higher temperatures so it’s best to avoid the hottest time of year.

Day before

The same as when making rice kōji, rinse the rice and leave it in water the night before. If the water you would use for soaking is hard, you can use a soft mineral water like Volvic. The next day, put the rice in the colander and let it drain for 1-2 hours.

On the day

1. Steam the rice

The same as when making rice kōji, the rice used for brewing must not be like wet like freshly boiled rice. So you don’t boil the rice, you steam it. Drain the rice before steaming.

Put water into the pan, making sure it doesn’t touch the steamer insert. If there’s too much water, the rice will absorb it and the grains will stick together. If there’s too little water the pan will boil dry, so be careful. Put a thin steaming cloth over the steamer insert, and the rice on top of the cloth. See the rice kōji-making method for details on steaming cloth.

If using a pressure cooker, steam for 20 minutes after reaching pressure.

If using a normal pan, steam for about 40 minutes. Be careful when using a normal pan as you can end up with rice sticking together. Using a pressure cooker gives a drier result. Rice that has stuck together is not suitable for sake brewing. Maeoka used a Fissler 4.5 L pressure cooker, which cooks 5 go [about 750 g/900 ml] of rice at a time.

If using a pressure cooker, leave it until the pressure has gone down after the rice has finished steaming. Put the rice with the steaming cloth into the plastic food storage box, open it up and use the rice paddle to thoroughly break up the rice. Turn the rice to avoid it sticking to the steaming cloth and becoming mushy. Keep the rice spread out in the box until it cools down and turns dry.

Maeoka recommends stainless steel steamer inserts over wooden ones as the latter can transfer a woody smell to the rice.

The firm steamed rice should turn translucent and not stick to your hand when touched. It should fall apart and feel hard if you try to eat it. If the rice is soft, white and swollen with moisture, it’s not suited for sake brewing.

To make brewing in Germany more like brewing in Japan with its soft water, Maeoka used soft Volvic water. All the well-known sake regions in Japan have great water sources, so water is important for brewing.

2. Dissolve the yeast in warm water, mix yeast and rice kōji with steamed rice and water

While the steamed rice is cooling, prepare the yeast.

Maeoka used live bread yeast from a German organic supermarket, but notes you could also use Japanese dried bread yeast or dried bread yeast from German organic shops. Just a tiny amount of bread yeast is enough to brew alcohol, so be careful not to put too much in.

If using dry yeast, use about half the amount that you would for live yeast. Dissolve the yeast in warm water, about 30°C, and leave to one side. For dried yeast, this process is very important as the yeast is activated by being dissolved in warm water.

Put the cooled steamed rice and 650 ml of water in a sterilised container. Stir well with a sterilised spoon until the rice grains are separated. Add the warm water with the yeast and the kōji rice, and stir well again.

3. Brew

  • The moromi (the mixture of all the doburoku ingredients) needs oxygen while fermenting. This means the container cannot be sealed. 
  • The yeast will emit carbon dioxide while the sake is brewing so sealing the container may cause it to explode.

Maeoka used a 2.7 L Weck glass jar and put one of their proprietary clips between the container and lid to provide ventilation.

Day one

After mixing all ingredients together, the kōji rice and steamed rice will be steadily absorbing water and the smell of bread yeast will still be strong. Place the brewing container in a cool, dark place. Cool temperature slows down fermentation, which produces more umami

After a short time the rice kōji and rice absorb quite a lot of moisture and the container looks dry, but the moisture will be released again after a few days as the brewing proceeds.

Day two

The rice has absorbed the water and the inside of the container looks dry, but the moromi should smell sweeter and more fruity than on day one. If the bread yeast smell has gone, that’s a sign that the fermentation is working. You can hear a soft popping of little bubbles coming out of the moromi.

If you tilt the container gently and have a look, you should see at the bottom of the moromi that the rice kōji and steamed rice are starting to release moisture and becoming damp.

When stirring, always use a sterilised spoon. Stir gently so as not to crush or knead the rice grains.

Day three

The moromi starts smelling alcoholic and has lots of bubbles. Mix with a sterilised spoon so air spaces are not contaminated by unwanted microorganisms in the air.

Day four

The moromi looks wetter than at the start. There are lots of air bubbles between the rice kōji and steamed rice.

Day five

The moromi should look completely different from day one. As the fermentation progresses the steamed rice breaks down in the moisture, and no whole grains should remain by the end of fermentation.

Day 12

The moromi is mostly liquid. It’s now extremely sweet with a fresh aroma.

  • The temperature at which fermentation occurs heavily influences whether the moromi has fermented fully or not.
  • If the moromi over-ferments, the grains of rice koji that you always see floating in the upper part of the container start sinking to the bottom. The flavour of the moromi itself becomes acidic.
  • Stop the fermentation before the sake becomes sour and turns into vinegar. If you don’t know when the fermentation is complete, just stop it when you like the flavour.

4. Filter

Maeoka used a large bowl and colander to filter the sake. The moromi contains lots of rice so it would take a long time to filter through a cloth. He found it quicker to leave the sake for 2 or 3 hours in a colander with slightly large holes as a simple filtration.

Beware of leaving the liquid in the bowl for too long, as exposure to the air can negatively affect the flavour.

If the liquid from the moromi in the colander won’t drain into the bowl, put a plate or container full of water on top of the moromi to press out more liquid. Put a cloth like one used for steaming between the moromi and the weight. Put the liquid in a sterilised storage container and keep refrigerated.

Done!

The finished doburoku is milky white. It’s also called nigorizake (濁り酒) or moromizake (醪酒).

If you leave the doburoku taken from the moromi, the ori (澱, sediment) will settle at the bottom. The liquid at the top, without any components of the moromi, is a beautiful mustard yellow colour. The upper part with no sediment has a more refreshing flavour, but you can also taste the flavour in the milky nigori.


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