This is the traditional koji-making process. Another method is to place hand-inoculated rice in special temperature-controlled chambers that look like ovens. There are also automated machines that stir massive amounts of rice with giant rotators. Ultimately, what matters most is the quality of koji produced.
Yeast Starter
As previously mentioned, the Japanese word for yeast starter is moto (which means the “base” of sake), or shubo (which means “the mother of sake”). Good shubo means good sake, so brewers aim to make excellent (and healthy) yeast starter for brewing. This is why starter is used to create a small, pure yeast culture of lactic acid that protects the starter from undesirable bacteria. Lactic acid either propagates naturally or is added. The main starter styles are kimoto, its offshoot yamahai, and sokujo-moto.
Kimoto
Kimoto (literally “pure yeast starter”) is one of the oldest styles of moto still used, dating from the 1600s. There is no official definition of how to make kimoto, nor are there any regulations that define the style. Generally, it’s characterized by mashing the rice and koji together with the oar-like poles in a technique known as moto-suri (often translated as “grinding the yeast starter”) or the more evocative sounding yama-oroshi (“grinding down the mountain”), referring to the mounds of rice in the mixing tubs.
To start the kimoto process, steamed rice is wrapped in cloth and cooled for 10 hours. (This step is essential; if skipped, sticky, glue-like rice will result, leading to subpar starter.) Once cooled, the rice is mixed with koji and water in small tubs called han-giri oke. When the rice has absorbed the water, brewers begin the work of mixing by hand or with small paddles.
Depending on the brewery, the next day can start with moto-fumi (or “stepping on the moto”) when brewers cover their boots in plastic and stomp on the rice to help break up the clumps. Since modern sake rice is polished more (and thus is softer), many breweries skip this step in making kimoto. Next, the process of pounding the rice mixture with oar-like poles, which must be done every three to four hours, begins.
In the past, brewers sang songs to stay awake during late-night moto-suri; the rhythm and tempo of the song helped make sure everyone was moving in unison. Moto-suri is carried out until the mixture reaches a puree-like state. The puree is then put into a single starter tank, during which nitric acid is converted into nitrous acid; this, along with sugars from the koji and the low temperatures, inhibits the growth of undesirable wild yeasts. Microorganisms living in the brewery, as well as in the wooden tubs, also contribute to the kimoto sake’s flavor.
Temperature control is paramount. It is accomplished by placing small sealed containers filled with ice or hot water into the tank. Dakidaru canisters containing hot water are used to raise the temperature. (It’s also possible to use heating plates, but they don’t ensure the same even distribution of heat.) The mixture starts at 46°F (8°C) and is slowly raised to propagate healthy lactic acid bacilli. These bacilli create the lactic acid that prevents the propogation of undesirable bacteria, and produces an optimal environment for the yeast. However, the mixture is so acidic that it first inhibits the nitrate-reducing bacteria and then the lactic acid bacteria.
Koji making involves inoculating the rice with koji-kin, checking the aroma of the rice, and placing the koji-innoculated rice into wooden trays.
Toji Yuji Nakamura of Eigashima Shuzo inoculates just-steamed rice with koji-kin as it’s transported down the cooling machine. Nakamura is the only toji who is also a master whisky distiller. When not brewing sake, he’s making Eigashima Shuzo’s White Oak–branded whisky.
THE ELEGANCE OF TRADITIONAL SAKE
The Daishichi sake brewery is unlike any other in Japan, with vaulted ceilings, wood paneling and marble floors. Landscape paintings cover the walls, and beautiful sculptures adorn nooks and crannies.
Daishichi’s specialty is the kimoto method. It uses this starter for its full lineup of sakes, which all feature good acidity and excellent umami. They’re sturdy, well-put-together brews that, if stored properly, improve with age. “Sometimes we get calls from customers who turn up old bottles of Daishichi, wondering if they’re still drinkable,” says brewery president Hideharu Ohta. “Our reply is, ‘If we still had that sake here, we’d sell it at a premium price.’”
Located on a quaint main street in Nihonmatsu in Fukushima Prefecture, a town that is famous for furniture making, the current brewery was built during the 2000s. Over the course of several years, production was moved into this new structure from the old brewery so the microorganisms clinging to brewers and employees gradually made the move too. “With kimoto, it’s not just the yeast, but the lactic acid, in addition to the numerous micro-organisms, that make a sturdy sake.”
The first-generation owner, Saburoemon Ohta, founded the original brewery in 1752, making Ohyama- branded sake. The third-generation owner, Shichiemon, focused the family’s business exclusively on sake, using the kimoto method. The brewery’s eighth-generation president, Ohta’s grandfather, made the fateful decision to continue that tradition.
“My great-grandfather passed away young and my grandfather took over the brewery when he was only 16 years old,” says Ohta. “Around that time, sokujo-moto was invented. According to the government, sokujo was easier than kimoto and harder to mess up.” Countless breweries went under due to bad batches produced by the kimoto method, which requires superb technique and impeccable hygiene. “The government directed breweries to use the sokujo method, and my grandfather thought it might be the future.” The brewery became the first in the region to begin test-brewing the new quick starter. “My grandfather found that no matter how hard he tried, he couldn’t make the flavors he wanted with sokujo, so he decided not to give up kimoto,” says Ohta. “Daishichi was quick to try sokujo and quick to say it was no good.”
During World War II, the brewery had to temporarily abandon the kimoto method because the brewers were enlisted to the army and there wasn’t sufficient manpower. After the war, Ohta’s father was keen to return to kimoto, but there still weren’t enough brewers, so he decided to try yamahai. “Yamahai sake, like sake made with kimoto, has personality, but it’s heavier and the acidity stands out noticeably,” says Ohta. With the yamahai method, the rice is left to dissolve, but according to Ohta, the starch might not completely saccharify, leaving a starter with a high percent of dextrin, which results in in a heavier sake. It wasn’t the Daishichi style, and the brewery soon returned to kimoto.
Later, I watch toji Takanobu Sato work a pole into a small stainless-steel tub of starter. His movements are controlled, but he’s not crushing the grains into a paste; rather, he’s moving them around into a puree. The Japanese word Ohta uses to describe the mixture is “sara-sara,” which is used to describe silky hair or smooth grains of sand. Looking closely, I see that the individual rice grains are intact as Sato