Rocket science: Why does food taste different in space?

By Flora Southey

- Last updated on GMT

Pic: GettyImages/Alexandr Yurtchenko
Pic: GettyImages/Alexandr Yurtchenko

Related tags Space exploration

Astronauts typically consume only 80% of their daily calorie requirements when in space, which could prove problematic on a long 36-month journey to Mars. Fresh research, which reveals links between food flavour and food intake, could help solve this issue.

Ever since man first walked on the moon, humans have set their sights on the next big challenge: a mission to Mars. 

While presumably countless challenges face space agencies in getting there, at least one revolves around food.

Calorie deficits

According to findings from life onboard the International Space Station (ISS), astronauts typically consume only 80% of their daily calorie requirements when in space.

While this calorie deficit is not of serious concern for astronauts who spend up to 12 months aboard the ISS, it does present risks for longer missions. A mission to Mars, for example, is expected to take 30-36 months to complete.

“As the prospect of long-distance space flight looms in the not-too-distant future, the importance of ensuring that astronauts maintain a healthy diet becomes an increasingly important issue,” ​explained Charles Spence, an experimental psychologist at the University of Oxford.

“However, while much work has gone into providing nutritionally sufficient meals for astronauts, a recurring problem is that many astronauts do not consume sufficient food while in space and hence tend to lose weight as a result. While this doesn’t matter too much for short missions, there is a great deal of concern about what this might mean for astronauts on a multi-year mission (e.g., to Mars and back).”

Does food really taste different in space?

The European Space Agency therefore commissioned a research report from a group of international experts working in flavour perception and the chemical senses to assess why this might be happening – and whether ‘poor taste’ might be a key factor leading to under-consumption, Spence told FoodNavigator.

The team of experts included representatives from Swiss flavour and taste company Firmenich, UK flavour solutions provider Flavormetrix, and numerous universities and research institutes across the UK, Germany, France, Belgium, and Italy.

Spence, who co-authored the peer-reviewed research report, noted that funnily enough, astronauts do not seem to complain about the taste of food in space. “At least, not in a way that would obviously explain the reduced consumption that time and time again has been reported,” ​he continued.

“The one complaint that does crop up time and again is the lack of perceived ‘freshness’ of the food.”

The report concludes that there are likely a number of factors responsible for the change in taste and experience of food and drink in space.

Airflow, background noise, stress levels

According to the findings, one of the major problems is that the lack of gravity in space means more blood tends to flow into the head than is normally the case here on the ground, Spence explained. “This can lead to swelling that can block or else seriously reduce the amount of air that can flow through the nasal passage.

“The importance of this constriction becomes clear when it is realised that 75-95% of what we think we taste really comes from the volatile-rich aromatic air that is pulsed out of the back of the nose when we swallow. This is what is known as retronasal olfaction – contrasting with the orthonasal sense of smell when we sniff.”  

The experimental psychologist also drew our attention to the dry air present aboard the ISS – much like that present on an aeroplane. “That may also impair the perception of aroma/flavour too, as it has been shown to do for aeroplane passengers.”

Beyond airflow in the nasal passage and dry air, astronauts on the ISS also have to put up with constant background noise. While this is typically lower than the 80-85 dB of engine noise that passengers have to contend with in a commercial aeroplane, the background noise on the ISS may still exert a significant masking effect.

“One of the other things to note,”​ Spence elaborated, “is that while we typically eat while seated down here on Earth, eating takes place in rather a different posture up in space, and this may influence the tasting experience more than we realise.”

The possible build-up of trace amounts of volatile compounds in the air/water supply, given the repeated recycling of both, should also be considered. As well as the fact that the foods are rehydrated.

“Other factors that might be relevant are that stress levels are likely to be higher and this has been shown to influence how food tastes,” ​Spence told this publication. “There is also a sense that normal diurnal and seasonal rhythms are muted in space, and I can’t help wondering if this might not also have some impact,” ​he added.

How should food makers respond?

Given these findings, how can manufacturers help make food more appealing for astronauts in space?

According to Spence, the answer does not lie in the development of a magic pill formula. “The one place where you might imagine that a meal in a pill would be useful is in space. [However, the astronauts] say that you can mess with anything, but not the food.”

The experimental psychologist puts this down to the ritual of mealtimes, which offer crew members an ‘important opportunity’ for social interaction. They can also provide a nostalgic or comforting link back to Earth, which Spence said ‘can seem like an increasingly distant memory, the longer the mission’.

“I think that the importance of psychological factors relating to foods undoubtedly becomes much more important in space.”

Making food more sensorially appealing could be one way to help avoid calorie deficits in astronauts. Drawing on the analogy between the loss of chemical senses with ageing and the reduced olfactory component due to swollen nasal passages in space flight, Spence suggested we look to ‘other channels’. This could include making foods more tempting by adding ‘a little oral pungency or spice’, he said.

The co-author has been especially interested in how to convey a sense of ‘freshness’, he revealed, “which is likely to be as much psychological as anything else”.

“One can think of freshly-made, simply garnished [food] with some space-grown microgreens. Or perhaps of how the noisier food – be it fresh produce like fruit and veg, or dry and baked goods – we tend to associated with freshness.”

Spence noted that some interesting work has been undertaken to determine whether letting the astronauts decide how to combine their meal components, or to specify what will be on the menu each day, makes a difference to their overall calorie intake.

“Perhaps unsurprisingly, giving people choice and some degree of control over what they eat tends to increase liking.”

The experimental psychologist continued: “Studying food and drink in space highlights, at least for me, how much of our relationship with, and experience of, food and drink is psychological/social. And this is something that food manufacturers here on the ground would do well not to overlook.”


Source:Comprehensive Reviews in Food Science and Food Safety
‘Factors affecting flavor perception in space: Does the spacecraft environment influence food intake by astronauts?’
DOI: 10.1111/1541-4337.12633
Authors: Andrew J. Taylor, Jonathan D. Beauchamp, Loic Briand, Martina Heer, Thomas Hummel, Christian Margot, Scott McGrane, Serge Pieters, Paola Pittia, Charles Spence.

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