A New Chapter in Seishu Brewing
It is said that the history of seishu brewing is over 1,500 years old. The sake production methods used until now were primarily established during the Edo period. A safe and reliable way to make sake became possible thanks to later advances in science and technology after the 20th century.
Usually, sake brewing takes around 30 days. First, brewer's rice is soaked in water, steamed, and then fermented with yeast and koji to produce sugar and alcohol. The moromi (a mash in the stage before becoming sake) is then strained. This fundamental process hasn't changed from the past. Science and technology have been conducive to quantifying the process and ensuring a stable supply.
While we've been making sake in Eiheiji in Fukui for over 200 years and have benefited from doing so, a question began to arise. Seishu brewing is an accepted culture that's been practiced continuously; it's gradually become more refined over a long time. The sake we cultivate with this in mind is ESHIKOTO AWA, which, as the name suggests, is a bubbly sake.
Until this point, the completion of moromi and the time to stop the fermentation process were arbitrarily decided. In contrast, ESHIKOTO AWA is bottled with the finished sake ori (sediment made from rice, yeast, sugar, and more) for a second fermentation. The yeast then eats the sugar and breaks it down. Eventually, carbon dioxide is produced, and natural gas accumulates in the liquid, which then turns into bubbles. It was the norm to stop the fermentation based on quantification, or in other words, setting a goal, but we got rid of that.
The secondary fermentation period takes 15 months, at the very least. It's kept in a cellar in ESHIKOTO's garyutou or a cool underground storehouse for one or two years. The gas doesn't accumulate infinitely; it stops generating activity at around three or four months, but the active source, yeast, doesn't die. It remains dormant and becomes biodegraded (the substance becomes inorganic) over a long time. Further, the sake in the bottle continues to change, as exemplified by the ori, which is a mass of proteins, turning into amino acids via chemical changes.
Conventionally, sparkling sake is often made from carbonation (the injection of carbon dioxide gas). However, adding carbon dioxide makes the taste acrid, and on top of that, the bubbles pop the second a bottle is opened, so it becomes stale very quickly. Contrastingly, gas born from natural fermentation lasts longer, has intricate bubbles, and has a complex taste that can't be achieved with fixed quantities or additives. Each bottle is subtly different from one another.
ESHIKOTO AWA can't be made within 30 days; one to two years is our current timeframe, but we can't set a clear goal because the course of nature comes before artificial creation. One can say that ESHIKOTO AWA will always remain incomplete. It may be unstable and mysterious, but we believe that's the true form of seishu.
