Since the founding of HAKUTSURU in 1743, the company has gone to great lengths to carry forward the wisdom of traditional sake brewing practices while incorporating new technologies. Today's brewing methods preserve the best time-honored practices and replace primitive methods with highly efficient, scalable ones. While using modern technologies, we maintain a traditional philosophy that recognizes the vital connection between personal dedication and technique in brewing sake. In this section, we present through photos and text each stage in the sake-making process, showing the contrast between the tools and techniques of earlier times (1920s and 1930s) and those of today.
The Main Stages in the Process of Making Sake
When mechanization in rice polishing evolved from the use of a foot-driven mill to a waterwheel, it first became possible to polish large volumes of rice with no physical effort. This led to advances in rice polishing and mass production; the sake industry in Kobe's Nada district flourished.
Industrial rice polishers
A high degree of control in rice polishing has become possible with the use of computer-controlled vertical cone polishers. Even the Yamada Nishiki variety of rice, said to be difficult to polish, is polished to 35% to make Dai Ginjo sake.
Preparing to remove the koshiki
Traditionally, rice was steamed in a steaming vat known as a koshiki, placed atop a large cauldron. The craftsman in charge of this process would carefully bring the cauldron to a full boil before allowing the steam to blast through tiny holes in the bottom of the koshiki to steam the rice. The photo shows a worker putting on protective footwear in preparation for removing the koshiki containing the steamed rice.
Vertical continuous rice steamers
Two steamers, each with a steaming capacity of 2.5 tons per hour, together can steam 5.0 tons of rice per hour. The steamed rice is sent to the next process after being cooled in a cooling apparatus.
Koji Making (Seigiku)
Breaking up clumps
Koji, made from a cultured mold, is essential to brewing sake. A portion of the steamed rice is transferred to a special room that is kept hot and humid. To evenly propagate good-quality koji mold is a two- or three-day, labor intensive process that involves working in two- or three-hour intervals -- mixing and re-mixing the batch to reduce variations in temperature and moisture content, moving and rotating trays (a very elegant dance to watch when done by an experienced worker), and twice rotating the vertical position of the koji. The photo shows the process of spreading out the steamed rice and breaking up clumps to ensure that the koji mold has adhered evenly. Even today, Dai Ginjo sake is made using this same traditional method.
Inside a koji-making machine
Steamed rice is sprayed with spores of the koji mold and put into a koji-making machine. After about 40 hours it is taken out as koji. During the process, the temperature is automatically adjusted and kept at 38 to 40°C (100-104°F).
Seed Mash (Shubo)
Making starter mash in open vats
In the Nada district, yeast starter was made according to the traditional kimoto method up to 1939-1940. As shown in the photo, workers would promote yeast fermentation by placing plugged heating buckets containing hot water, known as dakitaru, into the main vat and stirring the mash to adjust the temperature.
Starter mash room
Today, a quick-fermenting method is used to make the starter mash. It takes about 10 days in jacketed stainless steel tanks (ten 6500-liter tanks and two 3500-liter tanks). Pure yeast culture is mixed with water and koji, and soon steamed rice is added and the temperature is adjusted constantly until the yeast starter is ready.
The Main Mash (Moromi)
Transferring the main mash using traditional buckets
The standard system of mashing takes place in three stages, called san-dan-jikomi. After the main mash was fermented to the proper degree, it was poured out from the preparation vessel and transferred to smaller vessels using traditional buckets.
The starter mash, water, koji, and steamed rice go into stainless steel fermentation tanks, and take two to three weeks to ferment into the main mash. The temperature of the room is maintained at 10-12˚C (50-53.6˚F), and the tanks are kept cool by cold water circulating through plate coils affixed to their outer walls.
(Fifty-six 20,000-liter tanks can prepare 19,600 kg of main mash per day.)
Traditional stone press
The main mash was poured into long bags and pressed lightly to separate the sake from the caked lees. Initially, about 1000 bags were pressed. The following day, the bags were pressed more heavily in a traditional press. After a full day of being pressed, when all the refined sake was squeezed out, the lees were removed. The photo shows a traditional stone press, the oldest method known to humankind. In modern terms, however, the pressure created simply by the natural weight of the stones was rather weak.
Automatic main mash press
The main mash aged in the fermentation room is poured into a newly developed automatic press, where it is separated into freshly pressed "new sake" and caked lees.
(70,000 liters are pressed per day.)
Inside a storage facility
Before the use of steel tanks, pasteurized sake was poured into storage barrels. The bubbles floating on top were scooped off and the barrels covered. Ten heavy stones were arranged atop the lids, sealing the barrels very tightly to store the sake safely through the summer months until autumn.
Outdoor storage tanks
Unpasteurized namazake and pasteurized sake are separately pumped into and stored in temperature-controlled, jacketed outdoor storage tanks.
(Forty-two 200,000-liter tanks and six 110,000-liter tanks.)
Bottling in the early days
Strained, clear sake (seishu) had long been distributed in casks made of select Yoshino cedar grown in Nara Prefecture, but bottles started being used in the late 1920s. The photo shows two women in traditional garb transferring the sake from barrels into bottles.
Paper carton packing line
Strained, clear sake (seishu) is flash sterilized using a plate heater, then poured into bottles or paper cartons for distribution. The paper carton packing line has a production capacity of 4000 cartons/hour.