NATHAN MYHRVOLD: Cooking is about using heat
to create chemical reactions in the food.
Cooked food isn't just hot food.
It's fundamentally different.
If you cook something and you put it in the fridge and make it cold,
it's still cooked, it's just cold now.
It doesn't go back to its same state.
Whereas if you take a piece of metal, make it hot, cool it down,
it's pretty much the same as it was before.
There's a chemical, an irreversible chemical change.
Now chemistry teaches us that chemical changes usually
require both time and temperature.
And the rate at which a chemical reaction will occur
is some function of time and temperature.
Broadly speaking, there's a whole set of foods for which the chemical reactions
we call cooking happen very fast, so fast that pretty much the instant
you reach a temperature, it's done.
Now if it's not at that temperature, it may not be done yet,
but doneness means bring to a temperature and then you're done,
that's it.
There's another set of foods where the chemical reactions are fundamentally
much more slow.
And in those slow reactions, we have to hold the food
at a particular temperature for a period of time.
Most foods that are in the fast group would include fruits, vegetables, eggs,
and fish, and tender meats.
If you are cooking a filet mignon, as soon
as it reaches a certain temperature, it's done.
For me I like rare about 120 degrees Fahrenheit.
I like medium rare to be about 130 degrees Fahrenheit.
And so the minute, the second, the actually tiny fraction of a second it
reaches 130, it's done.
But tough meats are fundamentally different.
Tough meats, that would be cuts like brisket,
like short ribs, like skirt steak, any of these tough cuts of beef,
or of any other meat, for that matter, even tough stewing chickens
or the leg meat of ground-dwelling birds like ducks or pheasants,
that tough meat is tough because it has something called collagen in it.
Now collagen is a topic totally unto itself.
But for our purposes here, the thing that's
different about cooking these tough meats
is that we have to cook them long enough to soften that collagen.
In traditional cooking, that usually means cooking a stew or a braise.
And a typical stew or braise you might cook for an hour, two hours, three
hours, even overnight in some cases.
And that's what traditional cooking was about.
It was about saying let's cook this stuff very slowly,
but at moderately high temperature.
As a result, braised or stewed meat tends to be gray, it tends to be dry.
Because that high temperature, also because of collagen,
winds up wringing the meat out from the inside out.
With sous vide cooking, we can cook at a precise temperature for as long
as we like.
And we can actually cheat this collagen curve.
We can get a rare or medium rare-like meat that's still nice and red,
it's still nice and juicy, but still degrade the collagen and make
that meat tender.
But to do that, we have to extend our cooking times very long.
That's because most chemical reactions follow
what's called Arrhenius' law, or Arrhenius' first law of chemical
reactions, that they're exponential in temperature.
So that means that the more you increase the temperature,
the faster they go at a dramatic rate.
With most food chemical reactions, if you drop the temperature by 10 degrees,
you increase the cooking time by a factor of 10
to get the same results if it's in this slow set of cooking around
collagen. As a result, we will do sous vide cooking for 24, 48, 72,
or even in one example, an oxtail recipe we have in modernist cuisine,
100 hours.
Now that requires a little planning ahead.
You don't come home from work and say, hey hon, let's have 100-hour oxtail.
You kind of have to plan it in advance.
The interesting thing is by cooking that oxtail for 100 hours,
or a short rib for 72 hours, or pork ribs for 48 hours,
you get a texture that is totally unlike what you would get from braising.
It's delicious, it's unexpected.
It's a way to take a meat and reinvent it as something entirely new,
and use something that's both got a lot of flavor in it
and is usually pretty cheap because we generally price meats
according to how tender they are.