Long Periods of Isolation Could Change the Way Food Tastes and Smells

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A recent study found that confinement and isolation may impact how people perceive food aromas.

Researchers from RMIT University compared the perception and emotional responses of 44 people in two different environmental scenarios, microgravity (or zero gravity) and isolated confinement.

The study, published in the Food Research International, aimed to help explain why astronauts say food tastes different in space and consequently struggle to eat regular meals over long missions.

Participants sat in reclined chairs to simulate microgravity in space and then underwent a simulation of the International Space Station (ISS), a confined and isolated area, using virtual reality (VR) goggles.

Eight aromas were tested: vanilla, almond, lemon, lemon myrtle, eucalyptus, peppermint, vinegar, and lemongrass.

Lemongrass was the only aroma that was perceived more intensely in the confined environment than in microgravity.

Smell is crucial to the experience of flavour, so when you cannot smell you lose much of your ability to perceive the taste of food.

“This foundational work is key to designing better space foods and enhancing the eating experience for individuals in isolated or confined conditions,” Co-lead researcher Julia Low told The Epoch Times in an email.

“They are also important for other populations on earth living in similar environments, such as the older adult population in nursing homes.”

Why Those Scents?

First author of the study, Grace Loke said the team considered different aroma categories and chose a few commercially available aromas to represent them.

“For example, trigeminal aromas—which are those that give off cooling, spicy, warming, pungent sensations—were represented by eucalyptus, peppermint, and vinegar,” Loke said.

Trigeminal aromas stimulate the trigeminal nerve, inducing various sensations, including freshness, stinging, burning, and tingling, generally termed pungent sensations.

Co-lead researcher Low said the team would test complex food in the future, but is currently focused on understanding the fundamental ways food aromas are perceived and the influence of space-like environments on this.

Aroma Perception in Space

Research into the changed taste astronauts report has previously emphasised microgravity, while this study focused on confinement and isolation.

Low noted that most people eat in a social setting.

“Results indicate that a remote, confined environment such as the ISS and a significant variation in personal sensitivities influence aroma perception, making certain foods smell strange,” she said.

“This research opens possibilities for personalised meal plans for astronauts and individuals living alone on Earth, showcasing VR’s potential to explore variations in eating when stressed.”

Loke said their pilot studies suggest no noticeable difference in how a narrow range of food aromas are perceived in a normal environment compared to a microgravity posture.

However, definitive conclusions require testing in actual microgravity.

This is because on Earth, gravity acts on bodily fluid, pulling it into the legs, whereas in space, this fluid is equally dispersed.

Consequently, the dispersed fluid blocks the nasal passage during the first few days, before the body adapts and the fluid shift balances. The blockage feels like a heavy cold and reduces the ability to smell, impacting taste.

Newman said future studies would combine VR and microgravity to better simulate the astronaut experience and design food plans for longer missions.

The study suggests a simulation using both environments could aid in training astronauts to adapt psychologically to confined and remote eating spaces.

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Emotions and Aromas

Aromas were perceived differently during the VR simulation depending on how the person felt.

For example, participants experiencing happiness or a positive emotion perceived the aromas of vanilla and almond as stronger.

However, even mildly stressed participants perceived the aroma of vinegar as less intense.

Co-lead researcher, Lisa Newman said the discovered link between stress and vinegar may explain why astronauts like to eat certain foods they don’t enjoy on Earth during missions.

For example, to combat the loss of flavour in space, astronauts generally request condiments such as hot sauce to intensify the taste.

It is unknown why certain smells are more intense with more positive emotions.

“It could be related to the chemistry of the aromas—particularly with almond and vinegar, they are known as polarising aromas (either strongly liked or disliked),” Loke said.

“Therefore, perhaps polarising smells are more pronounced with positive emotions—this warrants further investigation.”

The Odd Scent Out

Of the tested scents, lemongrass was the only one perceived more intensely in microgravity.

“Lemongrass consists of a more floral and earthy aroma, while the other aromas are pungent, spicy or sweet,” Loke said.

“This difference in profile may explain why lemongrass seemed less intense in the VR setting compared to the microgravity posture.”

However, it is unknown why floral and earthy aromas smell stronger in simulated microgravity than in the confined VR experience.