Yukimuro (literally, snow cellar in Japanese) were natural refrigerators found in the "snow country" of Niigata Prefecture, where fresh foods were stored all year round. A brewery in the same prefecture uses snow refrigeration to produce "uniquely mellow and rich" sake today.
One of Niigata Prefecture's heaviest snowfall regions is Minamiuonuma City in the southeast. Snow cellars, or yukimuro, made from snow accumulated during the winter and insulated with straw and other materials, were used all year round to preserve foods, including vegetables and fish, before electric refrigerators spread throughout the country.
In 2013, Hakkaisan Brewery Co., Ltd., which produces sake in the foothills of Mt. Hakkai, built the Hakkaisan yukimuro. System components include a natural convection snow cellar with three layers of insulation, a snow-cooling chamber that can store 1,000 tons of snow, and a storage chamber. The chamber's internal temperature is naturally kept between 3 and 4 degrees Celsius. The facility's tanks hold 360,000 litres of maturing sake, equivalent to 200,000 1.8-litre bottles. By letting cool breezes pass through the yukimuro, cool air is created and used as "snow cooling" to replace part of the electricity present in the refrigerators of sake and other fermented foods stores. Several awards have been bestowed upon the yukimuro building for its simple yet modern architecture that blends seamlessly with its surrounding environment.
The Hakkaisan Brewery
Hamasaki Kozue, Hakkaisan Brewery's public relations coordinator, discusses the brewery's facilities. "In March 2011, the Great East Japan Earthquake prompted the construction of the Hakkaisan yukimuro. We studied the ancient yukimuro tradition in Uonuma as an alternative to conventional energy. Snow is a nuisance that works in our daily lives, causing traffic disruptions and clogging our gutters. As a result, we reframed snow as a 'resource' and proactively capitalised on the advantages of our snow country location."
The Hakkaisan yukimuro is said to give sake a mellow flavour after being stored for three years. The company has been selling the so-called snow-aged sake since 2016.
"Sake stored in temperature-controlled tanks transmits a faint hum of the machines to the sake inside them," Hamasaki explains. The yukimuro, on the other hand, is extremely quiet since there are no machines to produce noise. With a low temperature and high humidity environment, sake develops a mellow and rich flavour.
Koshihikari, one of Japan's most delicious rice varieties, is grown in the Uonuma region. As well as sake, Hakkaisan yukimuro sells local produce such as Koshihikari rice and vegetables to customers in their on-site shop. They are mainly known for plump rice and sweet root vegetables.
Daily tours are available at Hakkaisan yukimuro. According to Hamasaki, the facility hosts a large amount of snow all year round. Even during summer, when temperatures exceed 30 degrees Celsius, it's as cool as a refrigerator inside the facility. The power of snow as a clean energy source becomes clear."
Hakkaisan yukimuro stores sake and vegetables by using natural energy rather than electricity. In doing so, it also conserves a legacy of wisdom inherited from the snow country's people, passing it on to their children and grandchildren.