Aeroplane food generally doesn't have the best reputation, because it usually tastes rather bland. However, this has less to do with the quality of the food than with the altitude. 

The taste buds are influenced by two factors in the aircraft: pressure and humidity.

The higher the aircraft climbs, the more the internal pressure in the cabin changes. The pressure atmosphere in the cabin at 35,000 feet causes the taste buds to go slightly numb, similar to a cold. You perceive a much less wide range of tastes, so the food simply loses its appeal. The dry air from the air conditioning dries out the nose and inhibits the olfactory nerves.

At this altitude, the perception of sweet and salty also drops by 30%.