In sake brewing, there is a term called kan-jikomi — literally “cold-season brewing.” It refers to the method of preparing and fermenting sake during the cold winter months.
Today, with temperature-controlled facilities, sake can technically be brewed year-round. However, in practice, most brewing still takes place from autumn through spring, when temperatures drop. After the rice harvest in autumn, breweries enter their main brewing season. And the higher the quality sought, the more likely the sake is to be brewed in winter. Why has winter been chosen?
The answer lies in the nature of fermentation — and in the history of sake brewing in Japan.
Morning Brewery Workers, 1956 /Courtesy of Ozawa Sake Brewery
1. “Shikomi” — The Brewing Process
Sake is a brewed beverage made from rice, water, yeast, and kōji mold. Steamed rice is inoculated with kōji mold, which converts starch into sugar. Yeast then transforms that sugar into alcohol. The process of combining steamed rice, kōji, water, and yeast to allow fermentation is called shikomi. Temperature control during this stage determines the aroma and flavor of the final sake. At higher temperatures, fermentation progresses quickly but can produce unwanted roughness.
At lower temperatures, fermentation advances slowly, resulting in a more refined and balanced taste. Winter naturally provides a low-temperature environment. The growth of unwanted bacteria is suppressed, and fermentation proceeds in a stable manner. Kan-jikomi can therefore be seen as a rational method that makes use of natural seasonal conditions.
The same principle can be found in other traditional Japanese fermentations, such as soy sauce and miso.
Ozawa Sake Brewery, 1937 /Courtesy of Ozawa Sake Brewery
2. The Establishment of Winter Brewing
Historically, sake was brewed in different ways throughout the four seasons. However, during the Edo period, the shogunate imposed regulations that restricted summer brewing. As a result, winter-centered production became widespread.
At the same time, it became clear that the stable low temperatures of winter produced higher-quality sake. The overlap of institutional regulation and quality advantage led winter brewing — kan-zukuri — to become firmly established.
During the agricultural off-season, laborers gathered at breweries, and groups of master brewers (tōji) traveling for seasonal work were formed across the country.
Ozawa Sake Brewery / Photo by ©FASHION HEADLINE
3. Sawanoi — Ozawa Shuzo （Ozawa Sake Brewery）
Located in Ome, Tokyo, Ozawa Shuzo（Ozawa Sake Brewery） was founded in 1702 and produces the widely loved sake brand Sawanoi. Though within Tokyo, the brewery is surrounded by mountains and uses spring water from Okutama as its brewing water.
Water accounts for the majority of sake’s composition and plays a decisive role in its character. The clarity of this spring water supports the quality of the sake.
The Tama River flows nearby Ozawa Sake Brewery /©FASHION HEADLINE
Inside the brewery, numerous tanks stand in rows — containing not only sake in active fermentation, but also sake in stages of maturation and storage. At certain times of the year, wooden vats can also be seen.
At Ozawa Shuzo, delicate daiginjo sake — which requires especially precise fermentation control — is brewed during the coldest months of January and February.
Before brewing begins, the brewers offer a prayer at the Shinto altar. Sake has long been intertwined with ritual practice and has traditionally been presented as omiki, sacred sake offered to the deities.
Iwashimizu Cave, which can be seen on a tour of Ozawa Sake Brewery /©FASHION HEADLINE
Ozawa Shuzo also offers brewery tours, where visitors can learn about the facilities and processes firsthand. Though located in Tokyo, it is a place where one can encounter the authentic craft of sake brewing.
Behind the transparent taste of sake lies the logic of fermentation, the history of Japan, and the air of winter. It is because of this depth that sake remains clear.
Special Thanks: Ozawa Sake Brewery
Today, with temperature-controlled facilities, sake can technically be brewed year-round. However, in practice, most brewing still takes place from autumn through spring, when temperatures drop. After the rice harvest in autumn, breweries enter their main brewing season. And the higher the quality sought, the more likely the sake is to be brewed in winter. Why has winter been chosen?
The answer lies in the nature of fermentation — and in the history of sake brewing in Japan.
Morning Brewery Workers, 1956 /Courtesy of Ozawa Sake Brewery1. “Shikomi” — The Brewing Process
Sake is a brewed beverage made from rice, water, yeast, and kōji mold. Steamed rice is inoculated with kōji mold, which converts starch into sugar. Yeast then transforms that sugar into alcohol. The process of combining steamed rice, kōji, water, and yeast to allow fermentation is called shikomi. Temperature control during this stage determines the aroma and flavor of the final sake. At higher temperatures, fermentation progresses quickly but can produce unwanted roughness.
At lower temperatures, fermentation advances slowly, resulting in a more refined and balanced taste. Winter naturally provides a low-temperature environment. The growth of unwanted bacteria is suppressed, and fermentation proceeds in a stable manner. Kan-jikomi can therefore be seen as a rational method that makes use of natural seasonal conditions.
The same principle can be found in other traditional Japanese fermentations, such as soy sauce and miso.
Ozawa Sake Brewery, 1937 /Courtesy of Ozawa Sake Brewery2. The Establishment of Winter Brewing
Historically, sake was brewed in different ways throughout the four seasons. However, during the Edo period, the shogunate imposed regulations that restricted summer brewing. As a result, winter-centered production became widespread.
At the same time, it became clear that the stable low temperatures of winter produced higher-quality sake. The overlap of institutional regulation and quality advantage led winter brewing — kan-zukuri — to become firmly established.
During the agricultural off-season, laborers gathered at breweries, and groups of master brewers (tōji) traveling for seasonal work were formed across the country.
Ozawa Sake Brewery / Photo by ©FASHION HEADLINE3. Sawanoi — Ozawa Shuzo （Ozawa Sake Brewery）
Located in Ome, Tokyo, Ozawa Shuzo（Ozawa Sake Brewery） was founded in 1702 and produces the widely loved sake brand Sawanoi. Though within Tokyo, the brewery is surrounded by mountains and uses spring water from Okutama as its brewing water.
Water accounts for the majority of sake’s composition and plays a decisive role in its character. The clarity of this spring water supports the quality of the sake.
The Tama River flows nearby Ozawa Sake Brewery /©FASHION HEADLINEInside the brewery, numerous tanks stand in rows — containing not only sake in active fermentation, but also sake in stages of maturation and storage. At certain times of the year, wooden vats can also be seen.
At Ozawa Shuzo, delicate daiginjo sake — which requires especially precise fermentation control — is brewed during the coldest months of January and February.
Before brewing begins, the brewers offer a prayer at the Shinto altar. Sake has long been intertwined with ritual practice and has traditionally been presented as omiki, sacred sake offered to the deities.
Iwashimizu Cave, which can be seen on a tour of Ozawa Sake Brewery /©FASHION HEADLINEOzawa Shuzo also offers brewery tours, where visitors can learn about the facilities and processes firsthand. Though located in Tokyo, it is a place where one can encounter the authentic craft of sake brewing.
Behind the transparent taste of sake lies the logic of fermentation, the history of Japan, and the air of winter. It is because of this depth that sake remains clear.
Special Thanks: Ozawa Sake Brewery
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