Miso Fermented in Space Has an Entirely Different Taste

Forget chalky freeze-dried ice cream or some individually packaged mashed potatoes. Astronauts aboard the International Space Station have now proved that delectable fermented delicacies like the Japanese soybean paste known as miso can be prepared in space.

This might sound like a big deal only to ISS residents who are craving some better meals, but it could have major implications for more ambitious space missions. One of the major issues with planning such voyages, which could include future trips to Mars, is the problem of keeping astronauts fed for extended periods of time. Being able to ferment their own ingredients could not only help with nutrition—it could also provide some much-needed joy and comfort in the form of delicious meals.

The road to this culinary breakthrough started in March 2020, when an international team of food scientists sent a package containing a mixture of soybeans, rice kōji, and salt up to the ISS. Once it arrived, the astronauts aboard were tasked with running an experiment to see if the mixture would ferment, producing the tasty paste we know and love.

The researchers who created the mixture described their reasons for picking miso in the journal iScience. Miso is experiencing a surge of interest within the food science community due to the “the diversity and uniqueness of miso microbial communities,” the researchers wrote. Other reasons were based more on practicality, as the paste’s “firm, solid structure” reduced the chances of leaks (a major concern in the sensitive ISS environment), and the timeframe to ferment miso fit into the 30 days they had to run the experiment. Miso was also ideal thanks to its strong taste and high nutritional value.

After 30 days, the now-fermented miso was returned to Earth, where its chemical and microbial composition was analyzed. The miso was also checked for potentially harmful microbes, and, of course, for taste.

There were some doubts as to whether the experiment would succeed. After all, the environment on the ISS has some key differences from Earth. There’s the microgravity, but also the presence of increased levels of radiation. Both could have interfered with the fermentation process.

Those fears, thankfully, were unfounded. However, despite the successful fermentation, when the researchers compared the space-made miso to samples created on Earth, they did find some differences. The ratios of various kinds of microbes were different, though they did conclude that the ISS miso was still, in fact, a miso.

“There are some features of the space environment in low Earth orbit—in particular microgravity and increased radiation—that could have impacts on how microbes grow and metabolize and thus how fermentation works,” said Joshua D. Evans, senior researcher and group leader at Technical University of Denmark’s Novo Nordisk Foundation Center for Biosustainability, in a press release. “We wanted to explore the effects of these conditions.”

Now, for what you really want to know: How did the space miso taste?

“The ISS miso exhibits some clear sensory differences compared with the Earth misos,” the scientists admitted in the paper, namely boasting a higher level of “roasted” and “nutty” aromas that affected the flavor.

The findings are the latest example of how far space food has come since John Glenn became the first human to eat in space in 1962 (he partially consumed a tube of applesauce). In recent years, produce such as lettuce has been grown (and eaten) aboard the ISS. NASA has even made developing new food technologies into a competition.

While missions to Mars and beyond are still years away from feasibility, figuring out how to keep astronauts fed without filling the entire spacecraft with snacks remains a logistical issue to be solved. This little bit of fermented, nutty miso could go a long way—literally.