As the capital of Japan from the 8th to 19th centuries, Kyoto enjoyed the prosperity to develop traditional arts. After relocation of the capital to Tokyo, it has remained the country’s historical and traditional artistic stronghold.Sake is one of these traditions of which Kyoto is particularly proud.
Matsuo shrine in western Kyoto was consecrated to the god of sake and the first sake brand in history, Yanagizake was produced here in Kyoto. One of the most well-known sake production areas, Fushimi, contains many of Kyoto’s 46 sake breweries which have developed their own sake production technique. Sake Experience Japan interviewed with the Head of Research at Kyoto Municipal Institute of Industrial Technology and Culture (KMIITC), Dr Kiyō Hirōka, regarding their research and development activities in and with the Kyoto sake industry.
Yeast plays a very important role on sake production. Even though the starter just accounts for approximately 7% of final product of sake, the propagated yeast in the starter increases dramatically in moromi (fermentation mash), which has a significant influence on the sake’s final flavor.
In wine industry the world over, wineries generally buy viticultural yeast from vendors. However in the sake industry, the Brewing Society of Japan (BSJ) and prefectural public research centers develop and distribute yeast varieties for a fee. In acknowledgement of the significance of yeast in sake quality, KMIITC has been developing and refining their own sake specific yeast for many years and distributing them to sake breweries since 1962
Since complex flavors have long been regarded as a fascinating factor of sake, KMIITC has followed the national trend of developing yeast varieties that release Ginjo flavors (so named because of the Ginjo sake category). Ginjo flavors are derived from isoamyl acetate (apple and “pale” flavors) and ethyl caproate (banana).
In cooperation with other research centers, KMIITC has conducted genetic and protein expression analyses to identify potential sake production yeast.
A BSJ yeast variety, named “No. 1601” enabled a higher productivity of desirable ethyl caproate but did not reach the sweet spot of fermentation ability that was sufficient to the task without losing the elegance of flavor. With untiring effort, KMIITS scientists finally developed a new yeast which can ferment properly even at lower temperatures. It was released in 2003 and named “Kyo-no-koto”. “Koto” refers to the Japanese musical instrument which produces a traditional, elegant tone from 5 strings, the auditory equivalent of the elegant flavor of sake produced using this yeast variety. Additionally, the instrument name koto referred to in the yeast name is a pun on the word meaning “ancient capital”, a perfect name for a yeast developed in Kyoto.
Since development, ten sake breweries have used this yeast for their products. “Jyurakudai” (Sasaki sake brewery),“Tanshu-Yamadanishiki” (Kitagawahonke brewery) and “Karaku Kyo-no-koto” (Shotoku sake brewery) are the famous examples of the Junmai Ginjo category of sake which are produced using Kyo-no-koto yeast. “Tamanohikari Iwai” is a well-known product in the Junmai Dai Ginjo category.
The other major substance which releases Ginjo flavors is isoamyl acetate. After developing “Kyo-no-koto” (favoring ethyl caproate), KMIITC focused on developing a new yeast which could produce higher amounts of isoamyl acetate. In 2007, based on KMIITC’s “No. 2” yeast, they developed “Kyo-no-hana”. Hana can mean either “flower” or “gorgeous” and refers to the floral aromas released when using this yeast.
Kyo-no-hana is used by three Kyoto breweries including Miyakotsuru sake brewery.
KMIITC has recently been developing a yeast which is suitable for the local sake rice variety, Iwai.
Iwai was developed the the Tango area of Kyoto prefecture in 1933. However due to the unusual height of the plant, it was prone to collapse (such as during high winds in typhoon season).Iwai has a higher shinpaku so is not suitable for sake with a high polish ratio. In addition, due to higher water absorption, it has higher solubility which requires a yeast with strong ability of fermentation at the beginning of moromi.
Therefore, due to the high crop failure rate and the challenges of actually using the rice in production, planting ceased for many years.
On the other hand, if an appropriate yeast (higher fermentation capability than Kyo-no-koto or Kyo-no-hana) is used, it gives sake a strong structure and deep taste and so in 1992 replanting began.
KMIITC responded to this need for an Iwai-compatible yeast and developed “Kyo-no-saku”. Kyo-no-saku produces less succinic acid (which is related to the body or depth of the sake). Normally there is roughly twice as much succinic acid than malic acid, but the almost equivalent amounts of succinic and malic acids achieved when using Kyo-no-saku and Iwai creates sake with a refreshing and well balanced body.
Since the development of Kyo-no-saku, Kyoto breweries can produce sake using all local water, rice and yeast. The most famous Junmai Ginjo sake using the yeast and Iwai in the Jyunmai Ginjo category is “Shinsei-Iwai” from Yamamotohonke sake brewery.
Due to the characteristic portability of rice (unlike grapes) the concept of “terroir”, so well understood in the wine industry, has not historically been a factor of sake production in Japan. Sake breweries have sourced good rice from famous production areas, regardless of the distance they needed to transport the rice. However, now that terroir is better understood, each prefecture now develops sake yeast suitable for the rice grown in their local area.
The idea of producing sake using locally-grown rice, locally-developed yeast and locally-sourced water is only going to increase in popularity. Dr Hirōka mentioned that it is hard to generalize the taste of “completely local” Kyoto sake because of such local diversity, but it is not hard to say that local Kyoto sake is sophisticated, well-balanced sake with a hint of elegance of flavor. We expect more development of new yeasts which will support the sake production of Kyoto for the future.
Kyoto has been nominated as the “World No. 1 travel destination” by US travel magazine Travel + Leisure two years running. By encountering traditional Kyoto food, sake and culture, they experience the authentic Kyoto. We believe that providing more information and experiential options to visitors, through a collaboration of public and private sectors, is a great new opportunity for the sake industry.