In the vastness of space, astronauts face a variety of challenges. Some are extremely serious, while others can be quite peculiar. Among the latter are the unusual taste sensations experienced with food. In fact, space explorers often describe the meals consumed in microgravity as bland and unappetizing.
A team of dietitians from the Royal Melbourne Institute of Technology (RMIT, Australia) and International Flavors & Fragrances (IFF, Netherlands) investigated the potential reasons behind these taste transformations in microgravity. According to the researchers, this phenomenon poses a significant issue, as some astronauts may struggle to consume enough calories.
How the Research Was Conducted
Previous studies suggested that the problem stems from the effects of microgravity on the distribution of bodily fluids, leading to swelling. This swelling reportedly subsided as the body adjusted to the new environment. However, some astronauts reported that their food-related issues persisted even after the swelling disappeared.
Grace Louk from RMIT, who led the study, and her colleagues also focused on how the mental state of astronauts affects their perception of smells and tastes. The scientists hypothesized that stress might be a contributing factor to the altered perception of familiar foods, as reported by Science Alert.
During the study, the team simulated conditions aboard the International Space Station (ISS) and placed participants in this environment. The simulated setting included objects to mimic floating in microgravity, “devices that created a sense of chaos and confinement,” as well as background noise reminiscent of the loud sounds experienced on the ISS.
The researchers provided volunteers with samples of three different scents: vanilla, almond, and lemon. Participants were asked to rate the intensity of each aroma on a scale from 1 to 5, first in a regular room and then in the simulated ISS environment.
Volunteers reported that the scent of lemon remained consistent in both environments. Meanwhile, the other two scents appeared more intense in the simulated ISS conditions. The researchers suspected that a key factor in this was benzaldehyde—a volatile aromatic compound found in almond and vanilla, but absent in lemon.
What the Scientists Concluded
While the study does not necessarily answer why astronauts’ sense of taste and smell remain dulled after fluid (swelling) reduction, it supports the hypothesis that odor perception is contextual. “It’s possible that some volatile compounds with common scent profiles (like sweet) are more likely to be influenced by context compared to others,” the authors speculated, considering ways to mitigate the issue.
If this is the case, identifying compounds that retain their appealing taste and aroma in ISS conditions—or even become more appealing in these new circumstances—could aid in developing personalized nutrition plans for astronauts.
The team also posits that the explanation for changes in food preferences may lie in the isolation and, consequently, the stress experienced by astronauts.
The findings could potentially have applications on Earth. “This research could help personalize the diets of individuals in social isolation (particularly in nursing homes) and improve their nutrition,” noted co-author Julia Lou.
The conclusions from the study were published in the International Journal of Food Science + Technology.