Title: Miso in Microgravity: Fermenting Flavor Aboard the International Space Station
For the very first time, the ancient craft of fermentation has been successfully conducted in outer space. An international team of researchers marked this revolutionary achievement by preparing and maturing traditional Japanese miso on the International Space Station (ISS). This initiative not only highlights the potential for food production in space but also offers intriguing insights into how microgravity and radiation might affect microbial ecosystems and fermentation processes.
Miso: A Microbial Wonder
Miso is a savory, umami-rich paste widely used in Japanese cooking, created through the fermentation of cooked soybeans with salt and kōji. Kōji is a fermentation starter culture made up of Aspergillus oryzae, a fungus that breaks down proteins and starches. Similar to sourdough and other fermented products, miso contains a diverse array of microorganisms shaped by its surroundings and creators, a notion known as “terroir.” This term, taken from winemaking, refers to the environmental influences that impart unique characteristics to regional foods—making this NASA-supported project a mission to achieve the first authentic “taste of space.”
Laying the Groundwork: Earth vs. Space
The experiment was initiated in Copenhagen, Denmark, where the team prepared a batch of miso and split it into three portions. One sample was kept in Copenhagen, while the second was dispatched to Cambridge, Massachusetts, and the third was sent to the ISS. Each sample was placed in an environmental sensing box that carefully tracked temperature, humidity, pressure, light, radiation, and chemical off-gassing levels.
After a month in space, the fermented miso was returned to Earth for extensive analysis, including metagenomics (the study of microbial community DNA), metabolomics (the exploration of produced chemical compounds), and sensory tests like double-blind taste assessments.
Accelerated Aging in Space
In contrast to the Earth-based samples, the space environment had a significant impact on the fermentation process. The miso on the ISS encountered substantially higher average temperatures—13°C warmer than the Cambridge sample and 16°C above the Copenhagen batch. This thermal advantage sped up fermentation and sparked increased microbial activity.
Chemical evaluations indicated a more complex aroma profile in the space-aged miso, with ester concentrations being as much as 30 times higher and pyrazines—compounds noted for their roasted, nutty fragrances—present at levels six times greater than those in the Earth-grown misos. The heightened levels of pyrazines are likely a result of the Maillard reaction, a series of chemical transformations that happen at higher temperatures and contribute to browning and flavor enhancement in cooked and fermented foods.
Additionally, the ISS miso showed elevated levels of asparagine and decreased levels of histidine, biochemical indicators related to fermentation maturity. Glutamate, the amino acid associated with umami flavor, was a prominent component in all three misos.
The Space-Fungal Link
Perhaps the most captivating finding was the genetic variation within the microbial populations. The miso from space contained more variations of Aspergillus oryzae than its terrestrial counterparts. This indicates that the heightened radiation levels aboard the ISS may have led to mutations in the fungal genome, a phenomenon that paves the way for exploring space-induced microbial evolution.
Though various microorganisms were identified, pathogenic species were located solely on the exposed surface areas of the pastes. Consistent with traditional miso preparation techniques, these surface layers were removed prior to consumption to guarantee safety.
Taste Test Results
In double-blind sensory evaluations, all three misos were considered enjoyable, but the Copenhagen miso was favored by the testers. The ISS sample, while complex and rich, was noted to possess a more matured, roasted flavor profile—quite distinct from the traditional miso taste. Interestingly, both Earth-fermented samples retained a slightly “beany” flavor, suggesting they may not have matured as effectively as the space-fermented batch.
Why Miso in Space?
Miso was chosen as an excellent candidate for space fermentation due to both practical and scientific considerations. As a dense paste, it posed a minimal risk of spillage within the microgravity environment of the ISS, which is particularly sensitive to spills and airborne particles. From a functional standpoint, umami-rich foods like miso can help mitigate the sensory dullness frequently reported by astronauts, who often experience reduced taste sensitivity during extended missions in altered gravity settings.
The Future of Space Food
This groundbreaking experiment illuminates how space conditions—particularly microgravity and radiation—can shape the chemical and biological progression of food. As humanity prepares for longer missions to the Moon, Mars, and beyond, comprehending how to cultivate and preserve nourishing, flavorful foods will be crucial not only for the well-being of astronauts but also for their morale.
Moreover, studies of this nature unlock new avenues in food technology—leveraging space-based techniques to create unique flavors and microbial strains unattainable on Earth. Might the next wave of culinary innovation emerge from orbit? Only time—and additional fermentation experiments—will reveal.