Could a spoonful of miso help astronauts feel more at home in orbit? In a first-of-its-kind experiment, scientists sent soybeans and mould into space to ferment aboard the International Space Station – hoping to boost not just flavour but morale. The results? A rich, roasted paste that rivals its Earth-bound siblings and hints at how body and spirit might be nourished on future space missions. This is not just about food – it is about flavour, identity and life beyond our planet.
The views from the International Space Station may be glamorous, but the menu is far from it – an astronaut’s meals are typically freeze-dried and repetitive. The microgravity of space dampening scent and perceived taste does not help. Together, this can lead to flavour boredom, which can reduce how much an astronaut eats and can even affect cognitive performance.
With ambitions for longer crewed missions, scientists are looking for ways to spice up space’s monotonous diet. Researchers from the Massachusetts Institute of Technology (MIT) and the Technical University of Denmark have notched a first for humanity – extraterrestrially fermented food. In 2020, the scientists sent a paste of soybeans and mould to the International Space Station for a month to see if it could successfully ferment into miso – a Japanese condiment with a powerful kick – under the unique conditions of space, including microgravity and elevated cosmic radiation.
Fermenting food in space is not about the novelty, says co-author Maggie Coblentz, who worked on the project as an industrial designer at MIT’s Space Exploration Initiative. It is about “giving astronauts more autonomy over the things they eat and finding new ways to preserve and grow food in these novel environments,” she explains.
Nutrition for astronauts will have to go beyond making sure they are “fulfilled from a macro point of view toward being actually nourished in every sense of the word,” adds Josh Evans, co-author and food researcher studying fermentation at the Technical University of Denmark.
Blast-off for miso
In 2019, Coblentz was working at an MIT laboratory dedicated to life support systems in space that go beyond the bare necessities –contributing to astronauts’ health and well-being – when she and her fellow laboratorians received an invitation to send an experiment to the International Space Station. Her payload would be about the size of a shoebox, one of six to fit in a microwave-sized module to be carried into low Earth orbit by a SpaceX shuttle swapping out the Station’s crew.
“We were given, quite honestly, the freedom to design our dream project,” Coblentz says. And that was to explore food fermentation in space.
Coblentz and Evans considered several foods and drinks to serve as their guinea pig. “We could not send something that was going to combust or explode or bubble over,” Coblentz says, which rules out many of the liquid fermentables that generate pressure as the microbes do their work. They settled on miso for its portability – as a paste, it is unlikely to spill – and its flavour profile. “A lot of astronauts crave really pungent things, like hot sauce,” adds Coblentz, and with its strong umami flavour, miso fit the bill.
Evans cooked up a batch of miso starter in Copenhagen, dividing it into three parts. One stayed in Copenhagen to mature, another travelled to Boston to ferment with Coblentz and the third was sent to mission control in Houston.
The shoebox-sized container for the spacebound soybean paste was loaded with instruments to measure the miso’s development and the conditions it experienced – including an environmental humidity sensor, a Geiger counter to track radiation from space, a system to monitor the gases the fermentation process released and a camera.
In March 2020, Coblentz took a leftover sample of the miso starter to Florida to witness its sibling blast off into space. “Rocket launches are surreal and magical, and it was crazy to imagine our little miso on board,” she recalls.
Taste-testers chime in
The soybean paste spent 30 days in space until it splashed down in the Pacific Ocean in April 2020. Once the condiment was back in their hands, the researchers assessed how it had fermented compared with its Earth-bound peers. Evans explains that they thought of the evaluation as a stepladder: first, did fermentation occur? Was the result safe to eat? Was it a miso? And the crowd favourite: was it tasty? “Because something could have fermented, but it could have been this disgusting, mutated product,” Coblentz says.
Chemical signatures in the miso confirmed that the fermentation was successful, and after genetic testing for potentially harmful microbes, the researchers were confident that the space paste was safe to sample.
Evans invited 14 Copenhagen chefs and food researchers to taste test the three soybean pastes, not knowing which one had had an extraterrestrial experience. “They were not necessarily miso experts,” Coblentz explains, “but they knew what miso was and understood how to speak in the language of flavour.”
Coblentz and Evans were pleased to see that the space soybean paste cleared the crucial third hurdle – “people liked it statistically the same as the other two,” indicating that it qualified as a real miso, Evans says.
Then, the researchers asked the taste testers to evaluate each of the misos on its aroma and taste. “We designed keywords and descriptors that would commonly be used to describe miso,” both good and bad, Coblentz says. Similar to fine wines, some scent notes are considered appropriate or desirable in a miso, whereas others, such as “beany” or “rancid” scents, are negative.
“The space miso was deemed more nutty and roasted compared with the other two,” Evans adds.
The space miso was also darker in colour than the two Earth misos, which the researchers attribute to a higher-than-expected temperature during the extraterrestrial fermentation. They believe that the space miso was warmer because of proximity to heat-generating machines – and the frequent jostling on its commute to and from space may have increased oxidation, which could also contribute to the darker hue.
The future of fermentation in space
“In an ideal scenario, we would have been able to have an astronaut actually taste it in space, in the full context. There is a term borrowed from French – terroir – that describes a unique taste of place created by the cultural and environmental context in which a food is produced. We are only beginning to understand space’s terroir,” Coblentz says. “Terroir is not just happening inside your mouth but taking in the full environmental experience.” Coblentz is among the rarefied few who have gotten close to space terroir – in August 2019, she tasted a sample of miso aboard a zero-gravity flight with the Space Exploration Initiative.
Looking ahead, Evans emphasises that “we should not just think about what fermenting foods in space might change for humans but also what it might change for the microbes too.”
The researchers found an increased rate of genetic mutation in the mould that had been to space, which they chalk up to exposure to cosmic radiation levels more than 100 times what we experience on Earth. “That could teach us more generally about how life changes and evolves when it is brought further into new worlds and new environments,” Evans concludes.
