French fries are a very popular food commodity across many cultural backgrounds on Earth and as such they may be appreciated by long-term space travelers. The process of frying in hot oil is associated with complex heat and mass transfer along with the growth and detachment of water vapor bubbles. These phenomena are strongly affected by buoyancy and gravitational acceleration making the study of frying at space conditions a challenging task. In their new work, scientists from the Aristotle University of Thessaloniki examined potato frying in hot oil during the short duration low gravity conditions achieved in ESA’s parabolic flight campaigns.
Strong evidence suggesting that frying in space is possible. Image credit: Lioumbas et al., doi: 10.1016/j.foodres.2022.112249.
“Dietary nutrition and uptake of Earth-like foods are extremely important aspects for the health and performance of astronauts, especially during future planned long-term space missions,” said Aristotle University of Thessaloniki’s Professor Thodoris Karapantsios and colleagues.
“Despite the major progress in studying and designing systems for crop cultivation in microgravity conditions in the last years, there hasn’t been equal interest in food preparation processes and cooking.”
“There are several reasons for this but it is chiefly because at present astronauts stay in space for a few months at most, so there is no serious nutritional or psychological need for Earth-like food habits. This, however, will change drastically in long-term missions, e.g., to Moon and Mars.”
To study how microgravity influences cooking techniques such as frying, the authors designed a novel experimental carousel-type apparatus that operates in weightlessness.
They conducted their experiments on two ESA parabolic flight campaigns, whereby an aircraft flies in repeated arcs to recreate brief moments of weightlessness.
“We filmed the frying process with a high-speed, high-resolution camera to capture the bubble dynamics such as growth rate, size and distribution, as well as the escape velocity from the potato, the bubbles’ speed and direction of travel in the oil,” they said.
“We also measured the temperature of the boiling oil as well as temperatures inside the potato.”
“The experiment hardware is automated and closed for safety. It maintains a constant pressure inside the frying chamber to avoid leaks, to prevent the oil from sloshing around and to use less energy in heating.”
The team found that shortly after the potato was added to the oil in low gravity conditions, vapor bubbles detached easily from the potato surface similarly to on Earth.
While more research is needed to fine-tune some parameters, it does indicate that astronauts will be able to have more than re-hydrated food on the menu as they explore new worlds.
“Apart from nutrition and comfort, studying the process of frying in space could also lead to advancements in various fields, from traditional boiling to producing hydrogen from solar energy in microgravity,” said Aristotle University of Thessaloniki’s Dr. John Lioumbas.
The results were published in the journal Food Research International.
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John S. Lioumbas et al. 2023. Is frying possible in space? Food Research International 164: 112249; doi: 10.1016/j.foodres.2022.112249
