Recently one of the youtube channels I follow, SakaguraKaetsu’s channel, has had a few short videos on pressing. Specifically, they have a couple on filling a fune (P1020493.MOV, P1020548.MOV) and a couple showing the Fukurozuri – 袋吊り- drip process (P1020495.MOV, P1020553.MOV). Watching the great care taken to fill the bags with moromi is really impressive. They leave no wrinkles at all in the bags as they lay down one bag at a time; again, very impressive and labor intensive.
As an aside, SakaguraKaetsu’s channel has hundreds of short videos on just about every aspect of the brewing process. Some are very good while others are not, but all in all, their willingness to take these videos and make them available is a huge service to the community. Back to the topic at hand…
When it comes to pressing, if you want to get the absolute best sake out of a batch you should use the fukurozuri method to produce Shizukazake – 雫酒 – or Shizuku – 雫 – for short. This method is very simple, just fill a bag with the fermenting moromi, tie it up so that it hangs above a collector for the dripping sake and let it drip. The resultant sake, slightly greenish yellow is by no means clear. Time will clear much of this as suspended matter precipitates out of solution. Sake, separated from the kasu (lees) in this manor is the best it can be!
The use of the fune – 槽 – is more common than the use of the fukurozuri method. It was once the main method used for pressing the moromi, shibori – 搾り- but has now been mostly replaced by the Assaku-ki. Fune pressed sake is second to shizuku in quality. It is close though and extracts much more of the sake than can be collected using the drip method. The first extracts of the fune, shown at the end of the second video, is very similar in color and clarity to what is produced in the fukurozuri method. However, what we are looking at in this case is sake only under the weight of other bags of moromi. Eventually a lid will be placed on the fune with a tremendous force used to press down on the lid and squeeze the sake from the kasu.
Joso -上槽 – the more formal name for shibori, is now most commonly done using an assaku-ki -圧搾 機 – press. The most well-known producer of assaku-ki is Yabuta. This method is far more efficient in pressing the sake from the kasu than these other two methods but still maintains a reasonably high degree of quality. There is almost nothing to see when a Yabuta is in use but I did find one video of an active Yabuta and one with the kasu being removed (Yabuta in action, P1000134.MOV). The reason there is nothing to see is because of the way the Yabuta works. It uses air pressure to squeeze the kasu, forcing the sake out through the mesh. The loud noise is the air compressor. Yabuta’s chart on the functioning of their machine is quite informative. For the most part, a pocket between two filters is filled with moromi and a bladder is then filled with air to force the sake from the lees. With the sake removed, the kasu is scraped off the filter and the process is repeated until all the moromi has been processed.
Homebrewers are unlikely to have an assaku-ki available for their use but the other two methods, modified for scale are well within reach. The fact that these methods tend to produce better sake does not hurt either. The only down side is the lower efficiency but in small batch production quality over efficiency is usually a good trade-off.