Known as “Dr. Shochu,” Masahiko Shimoda has long been involved in honkaku shochu production at Sanwa Shurui, both as an engineer and as an executive. In this series, he explores the appeal of honkaku shochu from multiple perspectives. Starting with this installment, Dr. Shimoda will walk us through the honkaku shochu production process step by step, following the traditional Japanese proverb that has long guided sake making—first koji, second moto (yeast starter), third brewing. This time, the focus is on the first stage, koji. It refers to the process of cultivating koji mold on steamed rice or barley to create koji. In this second installment, Dr. Shimoda explains in detail how the raw ingredients are prepared to provide an ideal environment for the koji mold to thrive.
⇒Vol. 1: Honkaku Shochu: The “Miracle Spirit” and 3 Reasons Why
As told by: Masahiko Shimoda, Advisor, Sanwa Shurui Co., Ltd./Composition: Kenji Inoue, Contentsbrain
● About the Saying “First Koji, Second Moto, Third Brewing”
The saying “First koji, second moto, third brewing” is a traditional Japanese proverb that expresses the relative importance of each step in the sake brewing process. It means that to create a good moromi⋆1 (the main fermentation mash), you must first have a good moto (also known as shubo, or yeast starter), and to make a good moto, you must begin with excellent koji (in sake, steamed rice inoculated with koji mold). In other words, the proverb emphasizes that koji making, the very first step, is the most important of all. Although honkaku shochu is a distilled spirit and differs in production method from sake, the first half of the honkaku shochu production process follows the same principle.
⋆1 Moromi: A mash consisting of koji—which is steamed rice or barley inoculated with koji mold—water, yeast, and other ingredients in a fermentation tank, in which saccharification and alcoholic fermentation have already progressed. When pressed, it becomes unrefined sake (genshu), and when distilled, it becomes the base spirit for honkaku shochu.
(Figure created by Masahiko Shimoda)
In the first installment, I explained—based on my years of experience and research—why I call honkaku shochu a “miracle spirit.” From this issue onward, I will focus on the production process itself to highlight what makes honkaku shochu so fascinating.
The first stage in honkaku shochu production involves two key steps: polishing and raw material processing, which prepare rice or barley so that koji mold can grow under optimal conditions; and koji making, in which koji mold is cultivated on steamed rice or barley to create rice koji or barley koji. The precision of the moisture control during the early processing stages has a profound impact on the final quality of the honkaku shochu.
Both sake and honkaku shochu production begin with koji making—the process of cultivating koji mold on a base ingredient. In general, polished rice is used as the substrate for koji in both sake and honkaku shochu. However, for iichiko, the honkaku barley shochu produced by Sanwa Shurui, polished barley is used instead.
“Polishing” refers to removing the outer layers of rice or barley grains by milling (pearling) to expose the white interior. Polishing brown rice (genmai⋆2) is called seimai (rice polishing), while polishing unhulled barley (genbaku⋆2) is called seibaku (barley polishing). The resulting grains are known respectively as polished rice and polished barley.
⋆2 Genmai and genbaku: Genmai is rice that has had only the husk (the outermost shell) removed, leaving the bran layer intact. Genbaku is barley prior to pearling (milling), retaining its hull and bran layers.
Cultivating koji mold begins only after the rice or barley has been fully polished—yet this polishing process itself requires considerable time and care.
When polishing rice intended for everyday consumption, only about 5% of the outer surface of the genmai is removed. This means the polishing can be completed quickly and with relative ease.
In contrast, for koji used in honkaku shochu, 10–30% of the outer layers of the genmai are milled away. Rice polishing for this purpose has two main objectives.
The first objective is to remove excess bran and germ from the genmai so that the koji can take hold more effectively. The second is to eliminate proteins, lipids, and other non-starch components that are concentrated in the outer layers. Removing these components has a major impact on the aroma and flavor of the resulting genshu, so the degree of polishing is adjusted according to the production approach and the desired quality.
For polishing rice used in sake and honkaku shochu, specialized rice-polishing machines are employed. If too much is removed at once, frictional heat can crack the grains, so the rice is circulated through a single machine multiple times, shaving it down gradually. Polishing to 70% (removing 30%) takes around ten hours.
By contrast, seibaku—barley polishing—is a distinctive technique that developed in Japan, where barley is eaten as whole grains rather than ground into flour. Barley has a hard seed coat and a thick layer rich in protein and lipids on the outside of the endosperm, which makes the grains prone to cracking during processing. In addition, barley has a characteristic recessed groove known as the ventral furrow—a dark line running along the center of each grain—which cannot be removed simply by shaving off the outer layers.
To eliminate the outer layers down into this indented ventral furrow, the barley is polished so that 30–35% of the outer layers are removed, resulting in a final milling ratio of 65–70%. Whereas rice polishing is done by repeatedly circulating the grains through a single machine, seibaku requires even greater care: more than a dozen machines of two distinct types, each with a different role, are arranged in sequence, and the barley passes through them one by one, with speed and pressure finely adjusted to prevent cracking while carefully polishing each grain.
Cross section of a barley grain. Because it has a recessed groove called the ventral furrow (dark line) running through the center, polishing is more difficult than with rice.
The quality of the seibaku process has a direct impact on the quality of barley shochu. For this reason, Sanwa Shurui works closely with barley-polishing specialists to ensure rigorous quality control throughout the polishing stage.
The two-row barley used to make barley shochu is also used in beer and whisky production, but those processes do not include seibaku (barley polishing). When people familiar with whisky—also a distilled spirit like honkaku shochu—learn how important seibaku is in shochu making, they often ask, “Why do you need to pearl the barley at all?”
Beer and whisky do not use koji mold. Instead, whole barley (genbaku) is soaked to encourage germination. Once the barley sprouts—becoming malt—the enzymes in the germ and bran layers become active and begin converting starches into sugars. This process is called saccharification. Yeast then ferments these sugars to produce alcohol.
In Western traditions, malt provides the enzymes needed for saccharification, while in Eastern traditions, those enzymes are supplied by mold—specifically koji mold. In honkaku shochu production, barley is polished so that koji mold can propagate efficiently. But polished barley will no longer germinate, which means it cannot become malt—so beer or whisky could never be produced from polished barley.
Before reaching the stage of “first koji,” there is another essential step: raw material processing.
This consists of four processes carried out in sequence: washing → soaking → steaming → cooling. Together, they form the critical first stage for producing high-quality steamed rice or steamed barley—materials that allow koji mold to grow uniformly on each individual grain.
Soaking refers to allowing the grains to absorb water. After polished rice or polished barley is thoroughly washed, it is soaked in water and then steamed. The key is to control water absorption throughout all four processes and adjust it to the ideal moisture level for growing koji mold, finishing the steamed rice or steamed barley to the proper condition for koji making.
Because water absorption continues to increase throughout the water-based processes—washing → soaking → steaming—the experience and intuition of the production staff are essential. During the soaking stage, polished rice has a natural tendency to stop absorbing water once it reaches a moisture content of around 24–26%, even when fully submerged. Steaming then adds a further 10% or so in moisture, giving a final steamed-rice moisture level of 34–36%. This moisture range is ideal for the koji mold used in sake production to propagate. When touched, the steamed rice feels like firm grains of cooked rice with very little stickiness. (There are three types of koji mold used in sake production—yellow, black, and white—which will be explained in detail in Part 3.)
On the other hand, barley absorbs far more water than rice, making the soaking stage more difficult to control. Although the ideal moisture content for koji mold to grow—around 34–36%—is roughly the same for barley as it is for rice, polished barley will keep absorbing water until it reaches a moisture content of nearly 60% if left unchecked. At that level, the moisture is far too high for koji cultivation.
When barley is steamed, its moisture increases by only 1–2%, which is less than rice. Taking this into account, the soaking stage for polished barley must be managed so that moisture ends up in the 32–34% range, without allowing the grains to take in excess water. Because the rate of absorption varies with water temperature, the process must be controlled down to the minute, with adjustments made according to temperature.
In most honkaku shochu production, rice is used for koji making because its raw material processing is easier to control. Even so, producers of barley shochu in Oita Prefecture—including Sanwa Shurui—insist on using barley as the substrate for koji. This is because the character of the raw ingredient directly influences the final flavor of the spirit. In other words, they value the distinctive taste that can only be achieved with koji made from barley.
Soaking and steaming bring the grains to the right moisture for koji. After steaming, it is cooled down to the proper temperature for making koji, leading to the next stage: seikiku, or koji making.
⇒Vol. 1: Honkaku Shochu: The “Miracle Spirit” and 3 Reasons Why
Main references: Nihonshu (Sake) by Hiroichi Akiyama (Iwanami Shoten, 1994); Washoku to Umami no Mystery (The Mystery of Washoku and Umami) by Katsuhiko Kitamoto (Kawade Shobo Shinsha, 2016); Gendai Shochu-ko (Modern Shochu Studies) by Mami Inagaki (Iwanami Shoten, 1985); Shochu no Rirekisho (The Resume of Shochu) by Yoshihiro Sameshima (Ikaros Publications, 2020); Awamori no Kokogaku (The Archaeology of Awamori) by Shizuo Oda (Benseisha, 2000).