Pressing

As you taste your filtered mash samples, you’ll eventually reach a point where the sweetness, umami, acidity, and alcohol become balanced and you will want to stop the ferment and press. In some cases, you’ll actually want to adjust the mash first, so you’ll either do a yodan (fourth addition), warimizu (water addition), or add brewer’s alcohol to artificially increase the ABV. These can all be done after pressing, but for best results they are typically done beforehand.

When you are ready to press, your options are numerous, but require various equipment to achieve. The basic choices are: Do Nothing (doburoku), Shizuku (dripping), Fune (think apple cider press), Assaku-ki (mash filter press), and Centrifuge (spinny thing that uses centrifugal force to separate liquids from solids). For the most part, homebrewers are going to use a pillowcase for dripping into a pot or some form of false bottom Fune press setup. Production facilities will do a large scale fune or Assaku-ki (Yabuta), which require specialized fabrics to ensure good results.

For the best possible sake, Shizuku is often used because it offers the least amount of rice destruction for the price, although Centrifuge is considered the best, albeit far more expensive. The less disturbed the rice grains are, the less proteins and fats are disturbed. This isn’t entirely comparable to wine, but you can kind of think of it like first, second, and third pressings that give you more and more of the grape “peel” flavor, rather than the pure sugars. 

The fune is considered capable of producing daiginjo levels of quality, yet just like wine there is a “first”, “second”, and “third” press of varying weights known as “Arabashiri”, “Naka-dare”, and “Seme”. The first is pretty much just gravity pulling the weight of the bags down on one another. This actually helps create a fine filtration as the rice particles pack up against each other. However, it also means some of them get through, so “Arabashiri” tends to have a slightly rougher taste. Once the weight settles and most of the pores have filled out, weight is applied to the top of the bags and the sake is directed to a separate container to hold “Naka-dare”. This is considered by many to be the best tasting of the presses. At some point their comes a point where the sake is not flowing as freely and even more weight must be applied. This is usually separated into a third container, known as “seme” which is effected by the crushing of the grains of rice as lots of weight squeezes out the remaining sake from the bags. Similar to the grape comparison, the crushed rice grains attribute more flavors, resulting in a more brash product.

Shizuku is very time consuming, but offers the least destruction to the rice, however the yield is not nearly as good as other methods. It can also introduce production issues because you need to keep the drippings bags cold and try not to expose them to oxygen as much as possible. Sometimes dry ice is even hung in the tank to prevent exposure.

Yabuta (assaku-ki) are very expensive and not something you will probably make on your own. If you are a small brewery this can be worth the expense, but you really should consider all the problems with keeping it cold and clean, as they can attract quite a lot of mold, flies, and start to smell if it is not kept properly. This will however produce the best yield because of the amount of pressure that can be applied. If you DO purchase one, you’ll want to make sure the design features bladders or “balloons” on each plate. This is an critical to ensure you get the most yield. In the west, these types of presses are typically referred to a Mash Filter Press.

Centrifuges are unlikely to be your choice as they represent the most expensive way to separate sake from the lees (kasu), but it can provide the most “nakadori” yield of all the options. It just has to be worth it for you. Most times, you won’t be able to say that.