The mash, exposed to the elements in the tank, is separated into raw sake and sake lees by the pressing process, after which it is stripped of the lees and filtered.

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This person will explain

Toji shop owner/producer Eri Nakano

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In 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.

The true nature of dregs
Freshly pressed raw sake contains a mixture of tiny solids, such as undigested rice fragments that have leaked through the holes in the sake bag, yeast, and enzymes produced by the koji mold. This is the lees.
The lees contain starch, protein, and fiber, and the yeast and enzymes in them sustain the fermentation process, causing the sake's aroma and flavor to change over time.

●Removal of lees
This cloudy raw sake is left in the tank for several days to allow all the cloudy components to settle. When the top layer becomes completely clear, the clear part is drawn off through the upper of the two drinking holes (extraction holes) at the bottom of the tank. This is called lees removal.
Any sake that falls at the bottom and cannot be poured out is also collected into a tobin, and after a few days, the lees and the clear liquid are separated.
(If you want to pack in the lees as well, remove them from the hole at the bottom called the "shita-nomi". This is what is written as "origarami").

●The monk is the unsung hero
When touring a sake brewery, you may peek into a tank filled with moromi, but it is unlikely that you will ever see an empty tank. The bottom of the tank is spherically raised, and this part is called the "bozu." Thanks to the bozu, the lees collect around the raised sphere, in a part called the bottom of the tank, making it easy to remove the lees. When the amount of content decreases, one side of the tank is jacked up and tilted, but this also makes it less likely that sake will remain in the tank. The bozu also supports sake brewing like an unsung hero, underneath the tank, by making it easier to insert the paddle and promoting the circulation of the moromi.

Filtration
After the lees are removed, the sake shines green and appears clear at first glance, but because minute cloudy components may remain, it is further filtered. Filtration is carried out to harmonize the aroma and flavor, prevent deterioration, stabilize the quality of the sake, and clarify the sake.

● Activated charcoal and diatomaceous earth
It is widely known that activated carbon is used for filtration, taking advantage of its high adsorption ability. It is particularly effective at adsorbing pigments, but there are several types, such as those that are good at adsorbing colors, aromas, and unwanted flavors, and they can be used or blended depending on the purpose.
It is said that during this process, the sake may acquire a carbonaceous smell, but the carbon components rarely remain in the sake, and such occurrences will not be overlooked during quality inspections after filtration.
Another method is to attach diatomaceous earth to the surface of the filter media as a filter aid, taking advantage of the porous nature of the diatomaceous earth to improve filtration efficiency. In this case, too, diatomaceous earths with different functions may be blended together.

A filter called a membrane
Membrane filters are suitable for removing fine particles, and can remove not only dregs and debris, but also starch grains and yeast. As the word membrane suggests, filters for removing particles and microorganisms are membrane-shaped.

●Is this the mainstream? SF filter
SF filters are able to thoroughly remove even the most minute components. This is the filtering method that is thought to be the mainstream at present. Inside a tube called a housing, a straw-shaped filter made of hollow fiber membrane with a thickness of 0.4μm or less is placed in a state similar to bundled somen noodles. The straw-shaped filter has minute holes, and liquid pumped in from the outside is filtered by passing through the holes.
The fact that it can filter without transferring odors to the filter media and can be washed with high-temperature water may also be factors that have made it popular.

●Swaying colors
The color of the moromi, which is neither chalky white nor unripe, but rather milky white or unbleached, is removed from the lees, filtered, and transformed into a clear liquid. Being captivated by the swaying color is also part of the enjoyment of sake.

Products that are shipped without filtering after the lees are removed are labeled "unfiltered."

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