Why tomato juice, which nobody likes on the ground, becomes a hit on board a plane

Many airline passengers around the world admit the same thing: tomato juice, which almost nobody buys in everyday life, suddenly tastes surprisingly good at an altitude of ten thousand metres. Scientists at the German Fraunhofer Institute for Building Physics in Holzkirchen have found a scientific explanation for this phenomenon — and it turns out to be linked to cabin pressure, humidity and the way our brain works in flight conditions.

The research was prompted by data from the German airline Lufthansa. Back in 2008, the company noticed something odd in its in-flight catering reports: passengers were drinking anywhere from hundreds of thousands to over a million litres of tomato juice a year — volumes comparable to beer consumption, Germany's traditional drink of choice, and at times even higher. Airline management decided to investigate why a drink that barely sells in ordinary cafés and supermarkets suddenly becomes so popular in the air.

For the experiment, Fraunhofer Institute specialists used a sixteen-metre section of fuselage from a decommissioned Airbus A310-200, placed inside a huge pressure chamber. Engineers recreated all the conditions of a typical flight: lowered air pressure, extremely low humidity, seat vibration and the constant drone of engines. Volunteers were seated in this artificial cabin and put through a series of taste tests.

The results confirmed the scientists' hypothesis. At cruising altitude, cabin air pressure corresponds to being roughly two thousand metres above sea level, while humidity often drops below 12% — a level comparable to the driest deserts on the planet. In such conditions, the mucous membranes of the nose and mouth dry out quickly. Since taste is largely shaped by smell, drying out these receptors significantly reduces our ability to distinguish flavours.

According to the institute, perception of sweet and salty flavours drops by 20–30% on board. That's why so many in-flight meals taste bland and flat, even though airline food is often actually saltier and sweeter than usual. Sour, bitter and umami flavours, however, suffer much less — and that's exactly what gives tomato juice its edge.

Umami is a term from Japanese describing a rich, "meaty" flavour produced by glutamates, which occur naturally in aged cheeses, mushrooms, fish sauces and ripe tomatoes. The thick consistency of tomato juice also moistens a dried-out mouth — so the drink ends up tasting balanced and refreshing at precisely the moment when almost everything else on the tray has lost its flavour.

Noise plays a role too. A 2015 Cornell University study found that at a noise level of around 85 decibels — roughly the level of a typical aircraft cabin's drone — the brain becomes less receptive to sweet flavours, while sensitivity to umami actually increases slightly. Amid the constant engine hum, the brain seems to unconsciously gravitate towards foods rich in glutamates, since these are the ones able to cut through the sensory noise.

There's also a simpler physiological explanation: due to low humidity and faster breathing at reduced pressure, the body loses fluids and electrolytes more quickly in flight than on the ground, often compounded by the mild stress of travelling. In this situation, tomato juice — especially lightly salted — works almost like a light snack, replenishing not just fluids but also potassium and sodium, without weighing down the stomach.

Psychology matters as well. Flying is perceived as a break from everyday routine, where slightly different rules seem to apply. Social learning plays its part too: when the passenger in the next seat orders tomato juice with a pinch of salt, some pepper and a slice of lemon, others subconsciously feel the urge to try the same — turning the drink into a sort of unspoken ritual of flying.

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Around Prague, based on reporting by seznamzpravy.cz