Greetings sake lovers!
Welcome to another little article from the series that throws little nuggets of sake information your way. Today we look at the miraculous technique used to make sake called the 3-stage fermentation process.
You might have seen the phrase danjikomi on sake labels or as a part of sake names before, but will have no doubt been oblivious to its meaning. Danjikomi is Japanese for ‘stage fermentation process’; it tells us over how many stages the ingredients were added. The standard sake fermentation process is made in 3 stages.
Why is sake made in stages?
The main fermentation stage of sake which takes place after ingredient preparation is called the mash or Moromi. The Moromi is basically the sum of all the ingredients mixed together in a 6000L tank. This is the bubbling cauldron where both alcohol conversion and sugar conversion take place together in the miracle of sake called multiple-parallel-fermentation. It is this miracle that makes it possible to produce such a high alcohol content: in the case of beer and wine, sugar conversion is only done once which means that there is a limited supply of nutrition that the yeast can convert into alcohol to begin with.
Just as a quick reminder, the main ingredients of sake are rice, koji (malted rice), yeast and of course water.
Instead of adding all these ingredients in one go, they are added in stages, normally 3. Why? you ask. Well, if all the ingredients were added at once, things would get a little out of control which in the past in some cases made brewing unsafe. This was a mistake that was quickly learned from. In actual fact, adding in 3 stages is a practice that begun around the mid 1800s in Japan. Brewers learned that gradual addition achieved a better balance of flavour; it’s easier to control the acidity levels of the yeast and more importantly prevents wild bacteria from proliferating in the mash.
The 3 stages of the 3-stage-fermentation process
Sandanjikomi or 3-stage-fermentation process — san is Japanese for 3 — is the standard way to brew sake in use by most breweries today. The 3 stages each have different names: stage 1 is referred to as Hatsuzoe, stage 2 is Nakazoe and stage 3 is Tomezoe.
The yeast starter is moved to the large fermentation tanks where it is joined by a small portion of steamed rice, koji and some water. The amount of steamed rice added in this stage is normally around 20% of the total prepared in the earlier stages of production. At this stage, because the primary aim is to increase the number of yeast cells to drive fermentation and produce glucose for the yeast to consume, more koji is needed than rice.
In this second stage, roughly twice the amount of rice and koji is added to the mix. Fermentation starts to gather pace during this stage. Incidentally, between the first and second stages there is a day where no ingredients are added; instead, the yeast is left to do its thing. In Japanese, they call this day of rest: Odori. Adding too many ingredients too quickly risks overwhelming the yeast. The environment inside the tank may change too quickly for the yeast to adapt.
In this, the final stage, the amount of steamed rice and koji added is twice that of the second stage. After fermentation has bubbled away for about a day the volume in the tank will have increased by up to 20-25%. From this point onwards, temperature control measures are needed to stop the fermentation from getting too hot. After about 3-4 weeks the fermentation will be complete.
Beyond 3 stage fermentation
Not content with 3 additions of rice, some brewers just keep adding. 4-stage-fermentation or Yondanjikomi (Yon is Japanese for 4) is probably the most famous. However, unlike the stages in the traditional 3-stage-fermentation method, the purpose is not to drive fermentation but to make the sake sweeter. A super sweet type of sake that sometimes comes alcohol free called Amazake is made this way. Within the industry, it is thought that beyond 4 stages, the additional additions do very little to the flavour and quality of the end product. However, while that may be true, the meer shock and awe that seeing the words 10-stage-fermentation on the bottle causes the drinker is worth it.
Here at KURAND, we are proud to showcase a great example of sake made with the 4-stage method.