Six things you need to know before eating airline food

1. Your food was probably cooked yesterday.

Most meals are pre-cooked on the ground, normally up to 12 hours before a flight's departure time. They're then flash frozen and kept in vast warehouses till they're driven across the airport and loaded on to planes.

Depending on the length of the flight – and the length of any flight delays – the food can be kept chilled on board for another 12 hours before the cabin crew finally fire up the ovens to reheat and serve it.

2. First class food isn't actually that special.

If you're in economy faced with an uninspiring tray of pasta, dreaming of the delicious steak frites you're sure they're serving in first class, think again.

Airlines farm out their food preparation to a handful of anonymous firms where workers go from one client to another all day. So your fancy upper-class dinner could have been made by the same people who work make economy class lunches. And you have to hope they don't mix them up.

3. It's never going to taste great.

Low air pressure and low humidity dry out our noses, which deadens our sense of taste. Scientists even say noise affects taste – so the hum of plane engines spoils our dinner. And it even gets dissed by chefs who help prepare it.

After being a culinary adviser to a major airline for years Gordon Ramsay recently said there's 'no way' he would eat in the air. 'I know where the food's been and where it goes and how long it took before it got on board,' he said.

4. It's got a secret ingredient or two.

Chefs and scientists try to make sky high dining a bit better. They know that certain extras help our enjoyment, so meal are overloaded with salt and pepper. They've also found something new, the so-called 'fifth taste' of umami, which perks up most foods at altitude. There's a lot of it in tomatoes, mushrooms and spinach – so expect more of those in airline dishes from now on.

5. It's not healthy (and we don't want it to be).

We lose our ability to taste sugar at 35,000 feet – so extra portions are added to plane food to compensate. And while portions may look small they pack a big punch. Oxford University professor Charles Spence says we consume an average of 3,400 calories on a typical long-haul flight – that's the same as six Big Macs.

And while airlines offer healthy options we don't normally pick them. Cabin crew say they often get just one fruit salad loaded on to a typical jumbo – and no-one ever orders it.

6. You can't even trust the water.

'For the past few years cabin crew friends have been obsessed by the fact that the water tanks on planes never get cleaned,' says Jennie Jordan. The water in these tanks is heated up to make tea and coffee – and as water boils at a lower temperature at altitude it never produces the perfect cuppa.

Worse, crew think the dirty tanks and pipes could have all sorts of bugs in them, which is why lots of them drink bottled water in the air and are gasping for a proper coffee when they land. - Prime