Rokko Terroir
(climate and soil of the Rokko Mountains)

The foothills of the Rokko Mountains in Kobe, where the Fukuju brewery is located, are a rich area blessed with everything needed to make delicious sake: climate, topography, soil, water, and more. With the famous mystical Miyamizu* water that springs from the Rokko Mountains, the highest-quality sake rice grown at their base, and the “Rokko Oroshi” cold winds that breathe life into Nada sake, Fukuju aims for even greater heights both through traditions passed on for nearly 270 years and over 13 generations and through innovative sake-making. Each drop of Fukuju’s sake is perhaps the fruits of the blessing of the Rokko Mountains and the passion of our people.

*In the late Edo period, Yamamura Tazaemon brewed sake in both Settsu Nishinomiya (today’s Nishinomiya) and Uozaki (today’s Nada Ward), and noticed that the flavor from his two breweries was subtly different. Using the same rice made no difference, nor did swapping the toji, or brew-masters. Whatever he tried, the sake from Nishinomiya was always better. Then in 1840, he finally tried swapping the water around, and discovered that it was the difference in water that was responsible for the difference in tastes. After that, Nada breweries competed to use the water from Nishinomiya (“Miyamizu” or “Miya water”), spreading the district’s fame across Japan as the best place to brew sake.

The subterranean river provided by the Rokko Mountains

The southern side of the Rokko Mountains has been said for years to be a place where rain falls “400 days of the year.” As there is so much rain, the water in the rivers that flow down the steep mountain slopes gush straight down to the mouths to the south. However, part of that water percolates underground, becoming groundwater. The Fudabasuji and Hoanji subterranean rivers are rich in minerals (phosphorus, potash, and iron), and by mingling with the Ebisu subterranean river, which contains high amounts of oxygen, the iron oxidizes and the water, after the iron is removed, becomes the perfect water for sake. This is the true nature of the mystical water of Miyamizu that has underlain sake brewing in Nada. Miyamizu, listed as one of the Hundred Great Waters of Japan, only comes to the surface in an area a few hundred square meters in size in Nishinomiya City.

Miyamizu contains more phosphorus and potash compared with normal well water. This phosphorus and potash are nutrients that the koji mold and yeast, both vital for sake production, love, and promotes a safe yet powerful alcohol fermentation process. The result is the refreshing yet rich, seductive taste of Nada sake, what is commonly called “male sake.” Fukuju’s “well-rounded, full-bodied flavor” is strongly influence by this Miyamizu.

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As iron can have a negative effect on taste, water with low levels of iron is considered ideal for sake brewing. In addition, sake brewed with water containing low levels of iron goes incredibly well when paired with the fish dishes that are an indispensable part of Japanese cuisine, especially ones like sushi and sashimi that use raw fish. Low iron levels in the water for sake means that it does not react with the iron in the fish or with the oxidized fat, so it can draw out the flavor of the ingredients without any of those strong raw-smelling nuances.

At Fukuju, we have recently been tackling new challenges to find the ideal taste. We are working on creating sake by drawing of the power of water in each stage of the process, blending the mystical water of Miyamizu with waters with different properties to create well-rounded sake that offers a mellow mouth-feel. The reason our sakes are described by customers as having “a dignified framework,” “a mellow and gentle mouth-feel,” and “a well-rounded, full-bodied flavor” is thanks to the bounty of the Rokko terroir and the wisdom and techniques of our brewers who draw on it.

Soil for growing high quality sake rice

The most important sake rice production site in Japan is the northern side of the Rokko Mountains, known as “Ura-Rokko” or “the back side of Rokko.” The Rokko Mountains were created through crustal displacement and upheaval. Stretching more than 30 kilometers east to west, their highest peak is 931 meters above sea level. The entire range is composed of almost pure granite formed in the middle Cretaceous period 100 million years ago. Since the major crustal movements that thrust the Rokko Mountains up over a million years ago (the Rokko Movements), numerous separate crustal movements have taken place and the granite has formed multiple layers. This granite then weathers to form sand and clay.

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This dissolved granite has a considerable effect on the soil of the rice-growing belt that spreads out along the Ura-Rokko. This granite-based soil contains montmorillonite (photo), which contains a lot of clay ores. These ores are rich in potash, lime, magnesium, and other minerals that form the fertilizer vital for growing tasty rice. As a result, the rice that grows there is of high quality, being strong and healthy with large grains. 

モンモリロナイト(花崗岩由来の鉱物)

Rice paddies have alternating layers of clay and sandy soil. One of these is a strong clay layer which prevents the water from draining away, encouraging root growth, and preventing the tall Yamada Nishiki rice grown here from toppling over. 

A climate suited to growing sake rice

The Ura Rokko region, unlike the southern slopes of the Rokko Mountains (Omote Rokko) with their heavy rainfall, are part of the Seto Inland Sea Climate, with mild weather and many fine days. There are 1,850 total annual sunshine hours, the average temperature is 14.4°C, and the total annual rainfall is 1,198 ml. The rice paddies are located in the foothills and valleys (about 200 m wide) running east-west between 50 and 200 meters above sea level. On summer nights, the warm winds from the Inland Sea blow north, but are blocked by the Rokko Mountains so the night temperatures don’t rise. This means that the day and night temperature difference during the ripening phase is more than 10°C, creating an environment for growing high quality rice.

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Yamada Nishiki, the sake rice grown from the Rokko terroir

In sake-making, we look for rice with three specific characteristics. First, as we use rice that has been polished (milled by removing the bran on the surface), the rice grains need to be large. The index we use is “thousand-grain weight, the mass of a thousand grains of rice, and for Yamada Nishiki this is between 25 and 29 grams, about 5 grams heavier than the equivalent amount of grains from a standard rice like Koshihikari.

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The starch known as the “white heart”

The second characteristic is the starch part known as the shinpaku, white heart, the opaque white portion in the middle of the grain (photo). The reason the shinpaku appears white is because there are spaces, so it is very easy for the koji mycelia to lengthen when making the koji mold. Enzymes vital for making sake are created when the koji mold sends out its mycelia, so the shinpaku is very effective for preparing the koji.

心白と呼ばれるでんぷん質

Finally, we need rice that is low in protein. Protein is what amino acids, the ingredient that provides “umami,” come from, but too many of them causes the flavor to become heavy and cloying, increasing the sake’s odd tastes. Yamada Nishiki having less Protein than other rice varieties creates Fukuju’s special “dignified framework.”

 

 The rice that matches all these conditions in the ideal combination is Yamada Nishiki. Fukuju’s sake production is intimately connected with the Rokko terroir, the rice paddies that are the beneficiary of its climate, and the Yamada Nishiki rice that is grown in these paddies. Yamadanishiki , combined with Fukuju’s fermentation techniques, creates our “well-rounded, full-bodied flavor.”