People have long said that the warm climate of Kyushu, the southernmost of Japan’s four major islands, is not suitable for making sake, and it is therefore predominantly a shochu-producing region. Geographically, the island of Kyushu can be roughly split into north and south along the prefectural border of Miyazaki and Oita, with that line continuing through the center of Kumamoto. What lies to the north is sake land, what sits to the south is shochu country. In theory, Kumamoto’s position encompasses cultures of both brewing and distilling that staple food of Japan: rice. Most sake breweries in the prefecture are close to Kumamoto City and the Aso region, while in the southern area known as Kuma in the Hitoyoshi Valley, there is nothing but shochu producers.
In past centuries and even today, the abiding reality is that warm climates present significant challenges for brewing sake. This was even more the case back in the Edo era (1603-1868). In order to hedge the risk of wasting rice by having fermenting tanks of sake go bad, the Hosokawa Clan, which ruled the Kumamoto region at that time, decreed that no seishu (i.e. sake as we know it) was to be made. Instead, the brewing industry focused on a type of sake known as aka-zake, or “red sake,” made by adding reddish ash to the fermenting mash, chemically making it more alkaline. Aka-sake therefore did not spoil as easily and was often used in cooking.
Modern-day sake production in Kumamoto more or less began when production of this aka-zake was all but abandoned. Since they had not made any sake to speak of until that time, they had a lot of catching up to do compared to the surrounding prefectures. To accomplish that, in 1909 the brewers of the prefecture formed the Kumamoto-ken Shuzo Kenkyujo, or the Kumamoto Prefecture Sake-Brewing Research Center. Soon afterwards, they invited Professor Kinichi Nojiro, a sake-brewing technician with the Ministry of Finance, to be the director of the group. Professor Nojiro, who would later become known as “the god of sake,” enthusiastically worked toward teaching the members of the group proper sake-brewing methods. The results were evident in 1920 when the brewery making the sake Zuiyo took first place in the Zenkoku Seishu Hinpyoukai, or National Sake Tasting Competition, and Kumamoto rose to instant prominence as a ginjo-producing region.
After World War II ended, this Research Center discovered and developed Kumamoto Kobo (yeast), which later came to be widely distributed all over Japan as “Yeast Number Nine.” It leads to sake that is said to be “lively and fruity in aromas, and smooth in taste,” and has contributed greatly to the image of ginjo-shu that is prevalent today. In the less than one century since giving up aka-zake production, a high quality standard of ginjo sake was established in this brewing region, even though it sits on the very southern end of regions where sake production is even possible. After that, the name Kumamoto became engraved in the history of sake as the “Mecca of Ginjo.”
The Kumamoto Prefecture Sake-Brewing Research Center in time became a formal company, and began producing and selling daiginjo and other sake products under the brand name Kohro, but the group still continues in its role of supporting the brewers of Kumamoto. They also continue to distribute two varieties of their yeast, KA-1 and KA-4, not only to the brewers of Kumamoto but to all of Kyushu and even breweries elsewhere in Japan. Both of these yeast strains are considered indispensable to producing good ginjo.
Kumamoto Kobo tends to produce more acid than most ginjo yeasts, and leads to a comparatively thick and rich flavor. The character of Kumamoto sake can be described as having full-bodied flavor underwritten with a pleasantly bitterness-tinged base. Beyond the qualities imparted by the yeast, overall Kumamoto sake tends to have a big-boned, solid and dense flavor profile resulting from the higher temperatures of fermentation and maturation that are a due to brewing in a warmer climate. Recently, though, there has been lots of discussion and attention on not only their yeast but their sake rice as well. Topics of interest include the revived strain Shinriki, as well as Gin no Sato, with a flavor similar to the venerable Yamada Nishiki, and the debut of the recently developed Kumamoto-only sake rice, Hana Nishiki. The flavor of sake brewed using these rice strains is aligned with the acidity-laced, dense style alluded to earlier.
Another factor that contributes to this type of sake, and one which applies to all sake from Kyushu, is the rich, sweet shoyu (soy sauce) that is preferred by the people of this region. Considering pairings with the typically rich-flavored, local Kumamoto delicacies like basashi (horse sashimi) and karashi renkon (lotus root stuffed with spicy mustard), heavy sake is more appealing than light sake. Also, this kind of sake is more likely to be accepted in a region so close to shochu country. Having said that, shochu is distilled and therefore is not the type of alcoholic beverage that has much of the flavor of the original raw materials remaining in the final product. This is particularly true of the mostly light-flavored local shochu of the Kuma region, which is distilled from rice, especially when compared with the shochu from other areas that are made with materials like Satsuma potatoes. Since both the sake and the shochu of Kumamoto are made with rice, it likely became necessary to demonstrate the appeal of the local sake and favorably juxtapose sake with shochu by bringing out many flavor elements. I myself think that the unique characteristics of sake from this southern region are a combination of factors that include climate, raw materials, local preferences in tastes, and market conditions.
Kumamoto rose in a short time to be a holy ground of ginjo production, in spite of the handicap imposed by the warm local climate and the fact that the previously prevalent product, aka-zake, called for a much lower level of technical prowess. It became an outstanding example of a newly emerged production region. The effects of the official national tasting competitions and appraisals on the advancement of sake brewing technology and the prefecture’s inextricable connection to the development of new production regions is immeasurable. This group includes Hiroshima, which prospered quickly around the start of the 20th century; Nagano, which came into prominence after Kumamoto; as well as Shizuoka, which exploded onto the sake scene in 1986 by winning a stunning ten gold medals at the National New Sake Tasting Competition. As sake production overseas is becoming more popular, it is important to watch and see whether yet another region of Japan will become a significant player in the sake market. In this context, I think that the historical significance of Kumamoto sake goes beyond mere yeast and ginjo.
In April of 2016, Kumamoto was hit by a strong earthquake. The sake brewers in the prefecture were seriously affected, and the aforementioned Research Center, located in the center of Kumamoto City, sustained significant damage, including having its tall smokestack collapse. Since the brewery supplies its yeast to other breweries all around the country, everyone in the sake brewing world was immediately concerned about the stock of Kumamoto Kobo (it goes without saying they worried about the brewers first). As John Gauntner alluded in Sake Today #9, if this yeast is not protected, the lifeline of ginjo brewing would be gone, and sake of that quality could never be reproduced. It would be a significant problem for all the breweries that depend on that yeast. Fortunately, the Research Center was designed with earthquakes in mind and employs backup generators for the refrigerators in which the yeast is stored. The brewers and the yeast were able to escape harm.
Nearly a year later, the region has just begun to recover from the disaster. Let us pray that their recovery will proceed quickly, much like Kumamoto’s original rise to prominence as a famous sake-brewing region.
