Miso maker pumps up volume to quicken fermentation

The Yomiuri Shimbun

NIIGATA — A miso manufacturer and a local underwater audio equipment firm, both in Joetsu, Niigata Prefecture, have teamed up to produce fully matured miso by having koji mold and soybeans directly exposed to music.

Fermentation and maturation usually take about six months, but the makers cut that time in half to about 100 days with the music. It is believed the miso matured faster because of something having to do with the music’s frequency, but this is still being studied.

The 105-year-old company Yamamoto Miso collaborated with Uetax Corp. to create the product, with the miso manufacturer saying it wanted to try something unprecedented. It has been put on the market in the city and became quite the topic of conversation.

The miso is being matured in a brewing tank filled with koji mold and soybeans, together with two round speakers about 12 centimeters in diameter, at a Yamamoto Miso factory. The music can be faintly heard outside the tank.

The Yomiuri Shimbun
President Mikio Yamamoto holds packages of miso fermented with music.

“There have been cases of music being played outside a tank, but I’d never heard of exposing miso directly to music,” said Yamamoto Miso President Mikio Yamamoto, who decided to take on the challenge.

It began when Joetsu Shinkin Bank talked about Uetax to Yamamoto Miso after the miso manufacturer consulted the bank regarding the development of a new product.

Uetax is proud of its high-performance speakers, as seen in the use of its underwater speakers for artistic swimming at the Tokyo Olympics. In collaboration with Shinshu University in Nagano Prefecture, the company has been working to study using sound to promote plant growth.

Applying the technology for speakers that can be used underwater or in hot springs, Uetax has developed a stainless steel speaker that does not rust even when placed in salty miso, and remains undamaged after sterilization with boiling water.

Yamamoto and his team started experimenting in 2019 to find out what kind of music could be suitable to brew miso.

They exposed miso to classical and rock music at various frequencies and asked Shinshu University to analyze the data. Based on the data, they decided to play piano pieces and rock music by artists associated with the city, alternating between high and low frequencies. They began preparing ingredients for the brewing process in April this year.

“If we can better figure out how the music affects [miso], we may be able to control the speed of fermentation, which until now has been left up to nature,” said Kimito Hara, an industry-academia collaboration advisor at Shinshu University.

The fully matured miso has a sweetness enhanced by koji mold, the firm said. Yamamoto said he was surprised by just how much the music sweetened the mold and cut the fermentation time.

The finished miso is sold at ¥972 for 500 grams. It is proving to be a popular souvenir, the miso firm said.

“At times like this, we want to create a buzz and liven up the whole town,” Yamamoto said.