Sake Brewing Guides Explained

Before I start discussing the sake brewing process in detail it is a good idea to explain the process of making sake and it's terminology which you will become more familiar with, if not already.

The four main ingredients used in brewing sake are:

• Water (Mizu)
• Kome-Koji (Koji)
• Steamed rice (Kakemai)
• Yeast (Kobo)

The sake brewing process starts off with brown rice being polished to remove the hull and the outer layers of the rice grain, which contain proteins and fats that can produce off-flavours in the sake.  The best rice to use is sake rice, which is different from the various table rice varieties as it has a larger grain with a concentration of starches in the centre.  This concentration of starches, similar to a round pearl, gives sake its flavour and aromas.  No all sake rice has a perfect concentration of starches and so only some varieties can be milled for use in higher grades of sake such as Daiginjo shu, which has 50% or more of the rice grain milled away.
Most sake home brewers will be used to using Sushi rice, which lacks this concentration of starches and has only 7% of the grain milled away.
The milled rice is then left to cool and absorbs a small amount of moisture, which serves to protect the grains from cracking during the washing, soaking and steaming process.

Polished rice is then washed to remove the powder coating from the milling process and then soaked in water until they have absorbed the desired amount of water, approximately 30%.
Depending on the milling rate of the rice soaking times will differ from seconds to minutes or hours if using  table rice.  The rice is then left to drain before steaming for 45 minutes to 1 hour.

The steamed rice can then be used as follows;

• To make koji,  a mould also known by it's Latin name Aspurgillus Oryzae is inoculated on the rice. Koji are responsible for producing enzymes that break down starches in steamed rice into fermentable sugars.
• Making a yeast starter called Shubo (mother of sake), formally known as Moto (sake yeast starter), which is made using a combination of steamed rice, koji, water and yeast.
• Finally the steamed rice can be used to feed the main mash called the Moromi.  The Moromi is created using a 3 stage doubling of steamed rice, koji and water called Sandan Shikomi, which comprises of Hatsuzoe (first addition), Odori (24 hour break to enable yeast acclimatisation), Nakazoe (middle addition) and Tomezoe (final addition).

Once the Moromi buildup is complete, the koji continue to convert starch to sugars and the yeast turn the sugar into alcohol and carbon dioxide, in a process called multiple parallel fermentation.
After 3-5 weeks, the Moromi will be ready for pressing, filtering, pasteurization and then placed in cold storage to mature before a further pasteurization and bottling.

Water is extremely important when making sake and makes up around 80% of the final product.  Both hard and soft water can be used, however the correct brewing process must be followed for the type of water used.  Water containing Iron or Manganese is not suitable for making sake.

In Japan, sake breweries use water treatments to mimic the famous water from Mount Rokko that flows through the Nishinomiya dsitrict, which gives this water it's name, "Miyamizu".
Miyamizu has very distinctive properties that has enabled sake brewers to produce high quality sake.  
Naturally low in iron and manganese, this water also contained high levels of phosphorous which promotes Koji-Kin growth and healthy fermentation.
The Miyamizu water from two sake breweries were analysed, follow this link for the journal, and found to contain the following minerals:

 In the UK the best water I have found for this job is Caledonian Scottish Mountain water, sold in 5 litre bottles for £1.06.
Caledonian Mountain water has:

Calcium         55ppm                                    

Magnesium    16ppm                             

Potassium        2ppm                                

Sodium          15ppm                                     

Bicarbonate 240ppm                          

Sulphate        28ppm

Nitrate            6ppm

Chloride        11ppm

By adding potassium and phosphates, this water can be made to mimic the Miyamizu.

 I am still trying out different chemical additions to achieve a close match to Miyamizu.  Potassium Chloride and/or Potassium Carbonate are both good contenders.  Finding the right phosphate treatment has been harder.  Phosphoric Acid seemed to be a suitable treatment and requires 1ml /100ml to achieve the 4.4ppm, however it is very acidic and a 2ml addition to 5 litres of water will decrease the pH from 7.4 to 3.2.  To counteract this potassium carbonate can be added to raise the pH.  The other options would be phosphate salts or a liquid fertilizer.

As I wanted to get my sake underway, I decided to add 2ml phosphoric acid to 5 litres of water and then added 1/2 teaspoon of potassium carbonate to correct the pH back to 7.4


Koji is a fungus, Aspergillus oryzae, grown on rice and used to break down starch into sugars that can be fermented by yeast.  The ideal temperature for Koji incubation is 35.5-37°C, when the Koji are most active, however exceeding 45°C will kill the Koji.  Humidity should be kept between 50-80%, however 90-95% will also produce good results.