Some 10 million turkeys are eaten every Christmas in the UK alone, yet it is a meat that many of us love to hate. After all, the line between tender succulence and a mouthful of dried sawdust can be wafer thin. Oven roasting, spatchcocking, spit roasting, deep fat frying… each cooking method has its pros and cons. But part of the issue with cooking the perfect turkey is down to the birds themselves.
Since the 1930s, turkeys have ballooned – more than doubling in weight as farmers have bred only the biggest, leanest birds. And because they can be so large and low in fat, the outer meat can be overdone and leathery by the time the middle is cooked.
As soon as meat reaches around 65°C, it starts to cook: the proteins unravel and coagulate, or ‘denature’, making the flesh firm and digestible. Supermarket turkeys are considered safe to eat when the deepest part of the meat has reached 70°C. At higher temperatures, the meat gets stiffer and drier.
Oven roasting is particularly dehydrating because the cooking chamber is so arid and because heat moves so desperately slowly from air into solids. Try hovering your hand in an oven at 150°C (which is the air temperature) and it will feel hot but not unbearable; yet a mere splash of 100°C water or oil would make your skin blister and burn.
A 180°C oven will take more than three hours to cook a 5kg turkey, whereas deep fat frying – immersing the turkey in the same temperature oil – will do the job in just 35 minutes. Spatchcocking (splitting the turkey down the middle and spreading it flat) lets heat pass into the deepest parts more quickly and more evenly, while spit-roasting cooks by direct heat radiating from a flame.
But in this brave new age of space adventure, perhaps it’s time to try something completely different. How about cooking it under the power of gravity by dropping it from space? We’ve all seen images of space shuttles and landing capsules re-entering the Earth’s atmosphere in a ball of flame – and that’s just like a good barbecue, right?
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Given that anything freefalling through the Earth’s atmosphere at speed gets very hot – a fiery 1,500°C for spaceships and meteorites alike – you perhaps wouldn’t expect to have much edible meat to serve with your Brussels sprouts, but you’d be mistaken. Let’s suppose you were to toss a whole fresh refrigerated 5kg turkey out of the hatch of a Jeff Bezos private space flight from a height of 107km, at the edge of space.
At first our intrepid bird will get a brief freeze – at this height, it’s a bracing -80°C. Hurtling towards Earth, this high-speed fowl may be setting a world distance record for a flightless bird but its travel time will be surprisingly brief. The first 50 kilometres will pass in a mere 100 seconds, at which point the bird will be diving at three times the speed of sound.
Only in the last 30 or so kilometres will the air be thick enough to slow it down and cause heating. At supersonic speeds, air will ram so hard into the spinning turkey that it will be compressed and heated. As soon as the meat’s surface temperature climbs to 130°C it will start to brown, causing the building blocks of proteins, the amino acids, to react with traces of sugar in the weird and wonderful Maillard reaction, imparting it with the aromatic meaty yumminess we associate with the festive roast.
Given the intense heating, likely approaching 500°C, the browning reaction will be largely leapfrogged into pyrolysis, or burning, in which molecules are literally ripped apart in the heat, turning charcoal black. Nevertheless, this torching will be mercifully brief as the bird will rip through the last leg of the journey in less than
30 seconds.
So what does that leave for the table? Because heat conducts so slowly through meat, most of the breast meat will be disappointingly rare. Only a very thin rim of meat underneath the blackened exterior would be ‘edible’. Of course, the force of impact will be huge, blasting and splatting the centrepiece of your festive feast to smithereens while gifting you with a pretty little crater. Gravy with that, anyone?
- This article first appeared in issue 371 of BBC Science Focus Magazine – find out how to subscribe here
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