One of the recent culinary discoveries in our household has been cooking meat sous vide. The process is pretty simple: meat is placed in a plastic bag from which the air is removed, then the bag is sealed and submerged in a temperature-controlled hot water bath1 until the temperature of the meat is the same as the temperature of the water.
A thick steak takes 2 hours or so to reach 125°F (51°C, rare) or 130°F (54°C, medium rare). The resulting meat is cooked evenly all the way through. Searing it for 30 seconds in a very hot pan to make it nicely brown on the outside is optional.
Salmon doesn't require as much heat as the beef. It's can be cooked nicely after 45 minutes at 120°F (49°C). Some even cook it at 116°F (47°C) or lower temperatures.3 That's not much hotter than the summer temperature in desert towns like Palm Springs, where the average high in July is 108°F (42°C).
People even voluntarily expose themselves to much higher temperatures (70-80°C) in saunas. Which raises an interesting question: why don't people cook when exposed to the same temperatures so effective for cooking meat and fish?
Charles Blagden - a British physician and scientist - studied that very question in 1775. Using a room that was hot enough to boil water (236°F/113°C), Blagden made observations on the effect of heat on both his own body and a dog.
As he reported to the Royal Society4, the dog panted and held out its tongue, but the symptoms did not show evidence of "ever becoming more violent that they are usually observed in dogs after exercise in hot weather; and the animal was so little affected during the whole time, as to shew signs of pleasure whenever we approached the basket [the dog was resting in]." After an hour in the heat, a thermometer placed between the thigh and flank of the dog read 110°F - higher than a dog's normal body temperature, but significantly cooler than the room. Blagden acknowledged he had a bit of trouble taking the measurement, and he thought that what he recorded was likely higher than the dog's actual temperature.
Blangdon's demonstration that the dog's body temperature could stay cool in a hot environment was an important one. But there was the possibility that the thermometer used to measure the room's temperature was grossly inaccurate, which would invalidate his results. The obvious control experiment was to see what happened to meat placed under the same conditions.
To prove that there was no fallacy in the degree of heat shewn by the thermometer, but that the air which we breathed was capable of producing all the well-known effects of such an heat on inanimate matter, we put some eggs and a beef-steak upon a tin frame, placed near the standard thermometer, and farther distant from the cockle than from the wall of the room. In about twenty minutes the eggs were taken out, roasted quite hard; and in forty-seven minutes the steak was not only dressed, but almost dry. Another beef-steak was rather overdone in thirty-three minutes. In the evening, when the heat was still greater, we laid a third beef-steak in the same place : and as it had now been observed, that the effect of the heated air was much increased by putting it in motion, we blew upon the steak with a pair of bellows, which produced a visible change on its surface, and seemed to hasten the dressing; the greatest part of it was found pretty well done in thirteen minutes.
So under conditions where a steak will quickly become well done, dogs (and humans) are able to maintain close to their normal body temperature.
As Blagdon observed, humans shed excess heat by sweating, which cools the body when it evaporates. We also flush, as blood flow increases to the skin. The fur on dogs would make sweating ineffective, but panting serves the same purpose. That ability to regulate our internal temperature is why humans - and all other mammals - are called endotherms.
Of course shedding excess heat can put an enormous strain on the body. Last fall three people died and 19 were hospitalized after a sweat lodge ceremony lead by a New Age "guru". And just last week there was a death during a sauna competition.
I say leave the high temperatures for steaks and chops, where they can do the most good.
Update 8/14: My husband pointed out that I should have included a link to this post at Sous Vide Cooking, in which a scientifically minded sous vide enthusiast brought a vacuum-sealed steak to a Swiss steam bath that claimed to be at 55°C (131°F) - perfect for cooking steak. You'll have to read the post to find out how well it worked.
1. We2 started out with the beer cooler sous vide setup, which only requires a beer cooler, resealable "Ziploc" plastic bags and a digital meat thermometer, but have graduated to a digital thermostat controlling water temperature in our CrockPot. And while steak sous vide is delicious, the most striking results have been with pork chops and chicken breast - both of which turns out very moist and tender.
2. And by "we" I really mean that my husband has done pretty much all the equipment setup and experimentation with different prep methods and meats, and I have happily eaten the results.
3. The best reference guide for sous vide cooking is mathematician Douglas Baldwin's "A Practical Guide to Sous Vide Cooking", which covers preparation, temperature selection, cooking times, and food safety in detail. The illustration of eggs cooked at different temperatures is especially cool (65°C eggs are the best!).
4. Blagden C. "Further Experiments and Observations in an Heated Room" Phil. Trans. 1 January 1775 vol. 65 484-494 doi: 10.1098/rstl.1775.0048 (full free article)