Even for those of us who’ve always dreamed of becoming astronauts, one thing is complicated to dispute: When we see what they eat inside the spacecraft, it doesn’t give us an appetite. But we’re only talking about what the food looks like. The astronauts are the ones who really know what it tastes like, and they’re demanding a change in their diet. Basically, the food didn’t taste particularly good, so a team of researchers set out to find out what was happening.
The study. Food scientist Grace Loke of RMIT University in Australia and colleagues led the research. The goal was to find out why astronauts often describe space food as “bland” and unappealing and to improve the meals in space.
The team focused on how a person’s environment and mental state can affect their perception of aromas, which highly influence how we perceive food. The results? The problem wasn’t the food but the astronauts and their environment.
Previous work. The researchers said they started their study with familiar ideas. Previous research has suggested that the problem might result from fluid shifts, an effect of weightlessness on how the body’s internal fluids distribute, which causes facial swelling that recedes as the body adjusts to its new environment.
Coincidentally, some astronauts had said that their problems with food persisted even after these effects of fluid shifts had passed. So, they changed the focus of their research by zooming in on the environment and the astronauts’ condition: Does a person’s environment shift their perception of taste?
Recreating the ISS. As Ars Technica reports, Loke explains there are many environmental factors that could contribute to how we perceive taste, from the size of the room and the color to the intensity of the lighting and the volume and type of sounds present. In addition, the smell of our surroundings and “even the size and shape of our cutlery. Many other studies covered each of these factors in some way or another,” she says.
Initially, the researchers tried to solve the mystery of bland food in space by recreating the ISS environment in virtual reality. “Certain environments are difficult to duplicate, such as the ISS, which led us to look at digital solutions to mimic how it felt [to be] living and working in these areas,” co-author Julia Low, a nutrition and food technologist at RMIT University, states.
The results. Volunteers said the lemon taste was the same in both rounds. In contrast, almond and vanilla seemed more intense when participants were in the virtual reality environment. These reactions are the opposite of what would be expected based on astronauts’ eating habits.
“The bottom line is we may smell aromas differently in a space-like environment, but it is selective as to what kind of aromas. We’re not entirely sure why this happens but knowing that a difference exists is the first step to find out more,” Loke points out.
Ingredients analysis. The next step was to use a mass spectrometer to examine the composition of the flavors the researchers used in the tests. The lemon flavor, for example, was lemon essential oil that the team applied to a cotton ball, which they placed in a sealed container until they gave it to the participants.
The vapors released from the container contained various volatile chemicals, including limonene, camphene, 3-carene, and monoterpene alcohols, such as linalool and carveol. The almond flavors had similar chemicals, but one notable difference was that the almond and vanilla flavors contained benzaldehyde while the lemon flavors didn’t.
According to Loke, “benzaldehyde naturally gives off a sweet aroma, while the lemon aroma, which did not have it, has a more fruity and citrusy aroma profile. We believe that it may be the sweet characteristics of aromas that lead to a more intense perception in [simulated] space.” In fact, this is what happens with the smell of books, for example.
The big question. Why does food taste bland in space? The researchers say their study supports the hypothesis that odor perception is contextual. They also suggest possible ways to mitigate the problem. They state, “Perhaps certain volatile compounds sharing common odor profiles (i.e., sweet) are more likely to be contextually affected compared to others (i.e., citrus).”
If so, they point out that identifying compounds that maintain or even increase their appeal in environments such as the ISS could help design astronaut diets.
Conclusion. The study concludes that the explanation isn’t in the food but in what the astronauts are going through. They’re in a situation where they’re isolated and uncomfortable. That’s what makes the food taste bland, the researchers say, not being in orbit. Therefore, smell perception and the environment play a crucial role.
The researchers add that the study could have implications on Earth, for example, at polar stations or similar locations. “The results of this study could help personalize people’s diets in socially isolated situations, including in nursing homes, and improve their nutritional intake,” Low concludes.
Images | NASA Johnson, Maksym Kozlenko
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