This has been proven by former QANTAS, JAL and NZAF pilot Captain Jeremy Burfoot:
All airline food comes from the same place: an industrial kitchen near the airport. The numbers are impressive. The Emirates flight catering centre in Dubai prepares up to 170,000 meals a day. Under 'internationally recognized standards' the food can be held in a chilled state for up to FIVE DAYS before loading. 'Internationally recognized standards' here means it's recognized internationally that this is totally unacceptable. Hot dishes are made in large industrial pans and decanted into plastic containers with foil lids before being blast chilled to around 5 degrees Celsius in 90 minutes. They're then stacked in chilled metal boxes and taken onboard.
Airlines have been notoriously bad at food service for a long time. On some flights, the plastic-wrapped sandwiches and limp salads are pathetic offerings. The hot meals aren't much better. And the food that airlines serve tends to be high in ingredients that aren't good for you. This is because sugars and fat help preserve the taste and texture of the food.
Now if you think that's bad/not bad, spare a thought for passengers on a British Airways flight (1-2 years ago) from the Caribbean to London Heathrow. Because of a stuff-up with the original catering being left unrefrigerated for too long, it had to be thrown out. Local staff and some of the cabin crew in the Bahamas 'winged it' and did a KFC run. Passengers in all classes on the 12-hour fight were served a small portion of KFC to tide them over. No matter what you think of KFC, after that long not eating, it must have tasted okay.
Now, I know I have probably exaggerated a little bit, the sky is one of the only places where packet food is the better option.
TIP: When flying, play some music or plug in some earplugs, because the noise of the engine actually has an impact on your taste. Also, the air in the cabin recircles out the back of the plane on average every 2 minutes, so you can't smell that good either.