Dryness and low pressure
When you step on an aeroplane, the atmosphere inside the cabin affects your sense of smell first. Then, as the plane gets higher, the air pressure drops while humidity levels in the cabin plummet. At about 30,000 feet, humidity is less than 12% –
drier than most deserts.
The combination of dryness and low pressure reduces the sensitivity of your taste buds to sweet and salty foods by around 30%, according to a 2010 study conducted by Germany's Fraunhofer Institute for Building Physics, commissioned by German airline Lufthansa. To investigate this the researchers used a special lab that reduced air pressure simulating cruising at 35,000 feet (10.6km) – as well as sucking moisture out of the air and simulating the engine noise. It even made seats vibrate in its attempts to mimic an in-flight meal experience.
But it’s not just about our taste buds. Up to 80% of what people think is taste, is in fact smell. We need evaporating nasal mucus to smell, but in the parched cabin air our odour receptors do not work properly, and the effect is that this makes food taste twice as bland.
So airlines have to give in-flight food an extra kick, by salting and spicing it much more than a restaurant on the ground ever would. “Proper seasoning is key to ensure food tastes good in the air,” says Brown at American Airlines. “Often, recipes are modified with additional salt or seasoning to account for the cabin dining atmosphere.”
Gerry McLoughlin, executive chef at rival US airline United, says he has to use “vibrant flavours and spices” to make in-flight meals taste “more robust”.