[Tell me what you're too embarrassed to ask now!? Series 14] About the process of pressing sake into the vat
One of the processes in sake brewing is "Joso". This is the process of squeezing the moromi and separating it into sake and sake lees. The most common method is to squeeze using an "automatic press". There are three methods for this: "Fukuro-tsuri", where the moromi is placed in a sake bag and hung up to be squeezed naturally, and "Tsutsu-shibori", which we will introduce today.

The process in which the fermented mash is pressed and separated into raw sake and sake lees is called Joso.
The cloudy moromi is not recognized as sake as it is. In order to be called sake, it needs to be filtered and the alcohol content needs to be reduced to less than 22%. Joso is also a process that fulfils the requirement of "filtering". In this article, we will talk about the method of squeezing the sake using a press called a "fune".
This person will explain

- Toji shop owner/producer Eri Nakano
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ProfileIn 1995, he opened the Japanese sake bar "Janapese Refined Sake Bar Tojiya" in Tenjinbashisuji, Osaka. He is active in various fields as a sake critic, seminar lecturer, and lyricist.
● There is a style for the tank
"I'll be riding the boat tomorrow, so please come if you'd like!" When I get a message like that, I get excited!
"Getting in the vat" means squeezing the moromi. Although it is called a "vat," it is not boat-shaped; it would be more accurate to think of it as an aquarium where goldfish swim at night stalls. It is a rectangular container with a weight attached to the top, and it is a press that applies pressure from above with a hydraulic cylinder to squeeze the moromi. The moromi packed in sake bags (nowadays most are made of nylon, but there are also cotton bags) are lined up in the pressing vat and stacked in several layers.
Pressing tanks have evolved from being made of wood such as keyaki, cherry, and ginkgo to concrete, enamel, and stainless steel. Nowadays, there are also tanks made of SUS304, an austenitic stainless steel with excellent corrosion resistance, which is made of iron with chromium and nickel added.
The vat I have seen most often is the Sase type press (Showa Seisakusho Co., Ltd.), which I think is the mainstream vat-type press. Other companies also manufacture and sell similar machines in various sizes, such as the Nagata type (Nagata Brewing Machinery Co., Ltd.) and the TM type Ginjo Press (Toyo Shokai Co., Ltd.), but it is not hard to imagine that there are not many brewing machinery manufacturers.
Also, the Yaegaki-style press, invented and manufactured by Yaegaki Sake Brewery (Yaegaki Group), uses a pump to pump the mash into a large, sheet-like bag called o-nuno, which is then stacked alternately with boards called yaita (made of aluminum, stainless steel, or wood). The vats are shaped like regular square prisms, and although there is no set number of layers, the several sites I visited had as many as 30 layers.
With this method, the liquid that seeps out from the large cloth drips down the sheet piles into the vat, so the liquid is squeezed so that it overflows above the vat rather than inside it.Since the liquid comes into contact with air, this method of squeezing seems to deliberately encourage oxidation.
● Manipulating pressure
The aforementioned vat pressing method uses mechanical power to apply pressure, but there is also a method of applying pressure by hand. This pressing method involves hanging a stone weight from a balance beam (a pole) and adjusting the pressure manually using the principle of a lever. This method is called "tenbin shibori" or "hanegi shibori". At the Saga Ruins (Ukyo Ward, Kyoto City), there are remains of a sake brewing facility thought to date back to the mid-1300s or later, and traces of the balance shibori (hanegi shibori) method of pressing the sake into the vat have been found, suggesting that this method has a long history. However, because it is an inefficient pressing method that takes too much time, it is currently only used in a few sake breweries. The length of the balance beam varies from brewery to brewery, but the one at Uehara Sake Brewery (Takashima City, Shiga Prefecture) is exceptionally long at 15 meters, and its appearance is stern and impressive. The brewery also has two different balance beams made of different materials, one made of oak and the other made of steel. However, the steel weight for the heaviest weight, which can reach one ton, eventually bent, so they now only use oak.
This is the balance pressing method (Hanegi pressing) where pressure is controlled by hand.
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