Now, meat would also absorb plain water, but the salt is key for a juicier turkey. Ladies and gentlemen, Sample A. That needs some serious gravy.
And here we go with the second sample. Wow, that does not even need gravy. For some, it's even too salty. So we are directly measuring if it takes more force to chew one versus the other. The tenderness machine agrees with me!
The perfect turkey is juicy inside, and outside it's got to be crispy golden brown. That color ain't just for looks.
It turns out browning the outside of meat is crucial for creating the most delicious flavor, thanks to a complex chain reaction. Now, if I'm not mistaken, Mr. Food Chemist, there's some food chemistry going on here.
The cooks show the difference on chicken cutlets, which are a lot easier to brown in a fry pan than a pound turkey. Heat is a form of energy that is transferred into the food. That energy can speed up the molecules inside the food, causing many possible changes. One of them that happens quickly, once the surface of the meat gets above degrees, is called the "Maillard reaction.
I have discovered browning! Henceforth it should be named after moi, Mallaird. The Maillard reaction happens on the molecular level.
As we've already learned, meat is mostly muscle, which is made up of protein. Proteins are made up of molecules called amino acids. The heat from your stove breaks down the bonds in protein chains, releasing the amino acids. GUY CROSBY: So, it's the actual chemistry that's being driven by the heat, so if you have something that's not going to heat up, you don't see these reactions taking place.
That sugar was there to provide the turkey's muscle with energy. Now, on the sizzling skin, sugar and amino acids combine to create new molecules that give the turkey that delicious roasted flavor we love and the brown color. GUY CROSBY: You take something simple, a few molecules, sugars and amino acids, and together, when they react, they can lead to the thousand different new flavor molecules created by the Maillard reaction.
You can thank the same reaction for the irresistible flavor of many things we roast, including coffee beans and chocolate. It's like Transformers. DAVID POGUE: My thirst quenched, we've got to finish off the turkey, and that means it's time for that delicious combination of stale bread, tasteless celery and tear-worthy onion: the stuffing! I want you to smell this onion. So, if I just take this onion and cut it right in half, by taking the blade and slicing, I've started a chemical reaction.
And now you can start to smell an aroma. Inside the cell of an onion there are enzymes. These are normally kept separate from the other molecules by a barrier. When your knife cuts the onion, these chemicals come together to form new molecules.
Some make you cry; others create the strong onion flavor. So you're actually changing the flavor of a vegetable according to the mechanical action of cutting it?
The more you go at it and more you release those cell walls, the more flavor and the more pungent aroma is going to come out. The key to great stuffing is getting the moisture out of bread. In stale bread, the water actually gets trapped inside the crystal structure of the starch granule. So while the bread may feel dry, it actually has lost very little of its water.
But for a stuffing it is still going to be too moist. That's going to make the stuffing gummy. So that's our science lesson in the chemistry that will be happening in your kitchen, when you cook your turkey. Sometimes, cooking is essential for survival… Take the cassava root… It contains a chemical called linamarin Inside your body, it becomes… Cyanide!
But cook it properly… And you get… Tapioca. That's right. Cooking can turn poison into pudding! Throughout history, man has sat around a fire, cooking and eating, but we humans are the only animals that eat cooked food.
Surely there is a good reason for it. He thinks that cooking was essential to human evolution. He says cooked food is easier to digest, and so, humans evolved to use their food more efficiently. This is the skeleton of an ape, and he is comparing our anatomy with our ape cousins. It paid us, once we ate cooked food, to get rid of all of this gut, because that's expensive. So it's efficient to get rid of that.
Understanding that and how we get energy out of our food is what Stephen Secor studies. There we go. It's just all very long and slender.
Secor x-rayed the python over two weeks. Bit by bit, the rat disappears, and all but the hair is absorbed by the python. Understanding where the disappearing rat goes can help us understand how our food nourishes us, minus the bones and fur, of course. To make this point, Secor says, it's useful to compare the rat with a cupcake. After all, to a python, a rat is basically a triple-layer German chocolate cake. Both of these have energy stored in them.
DAVID POGUE: Now, even though we don't find these two treats equally appetizing, from the point of view of digestion, what they have in common is that they both are full of potential energy, or calories. To understand what kind of difference cooking can make to your food, you need to first understand a calorie. Think of this cupcake as fuel, like a log on a fire.
If we burn it, that fuel will increase the heat of the fire. A calorie is way to represent that increase. Items put in the bomb calorimeter must first be dehydrated, since water doesn't burn. Luckily, Secor is prepared for that. A portion of the dried rat goes into the bomb calorimeter, where it's burned in a special tank, sensitive enough to measure the heat, or calories, in the rat.
We do the same thing with our pink cupcake: dehydrate it, grind it up, make a pellet and, as the grad students like to say, "bomb it. The bomb calorimeter says that seven ounces of cupcake has twice as many calories as seven ounces of rat: impressive and disgusting. Now, let's take it one step further.
Those calories come from the basic elements of eating: proteins, carbohydrates, which are simple sugars, and fats. Secor has calculated the percentage of each in our cupcake and rat. No matter what we eat, whether it be a cupcake or a rat, those are the things your body is going to extract? It's almost the entire cupcake by volume. And you know the fat is quite a, quite a dollop, too. And over here we have so much protein and far less sugar and fat.
The rat looks like it would be healthier lunch than the cupcake. It turns out that the act of digesting a meal takes energy, too, like that big plate of barbequed ribs. Even as I lie here, my body is working to break down that dinner. And that energy I burn digesting takes away from all the fuel in the food. Some of the calories are always lost in the process, and that is where cooking comes in. Cooking made digesting easier. Here is one big place.
This brain is about three to four times the size of this brain. That's a lot of calories. So it was our brain, the largest, proportionally, of any primate, that Wrangham believes benefited most from a nice cooked meal. Wrangham says getting more energy out of food with less sweat was a key factor in human evolution. Cooking was a real timesaver! So if we were a great ape, like a chimpanzee or a gorilla, we estimate that we would have spent about six hours a day just chewing.
And we know that the human brain was already evolving, long before that: about 1. Wrangham is confident that older evidence of cooking fires will eventually turn up. But, in the meantime, he's hunting for other evidence to support the theory.
When he heard about Stephen Secor's work, he wondered if the snakes could help to illuminate just how much energy cooking actually saves. Secor can easily measure the energy it takes a python to digest food, just like he was able to measure how many calories it took for me to digest that plate of ribs.
But there was a problem: pythons don't eat what we do; they like their meals furry. So how do you make a python eat a steak? That was a challenge for Secor and his grad students. Believe it or not, this is what they figured out. They sewed a rat's face onto a steak. So we need to sort of entice them to eat the steak.
And with that, he can figure out the caloric cost of digesting the raw versus cooked meat. The result? It turns out that cooked steak takes 12 percent less energy for the python to digest than raw steak.
So what about vegetables? Not even a rat's face will make a python eat broccoli. Fortunately, bearded dragons love vegetables, raw or cooked. The bearded dragon experiments show that cooked vegetables take 40 percent less energy for them to consume than raw ones. So the python and the bearded dragon help to show that eating cooked food takes less work to get the energy from the fat, protein and sugar in our food.
There is still the unsolved mystery of when campfires and cooking started, but we know that the impact of cooking has been enormous.
Wrangham says cooking changed many things for humans, by giving us more time and energy to communicate around a fire or even more time to make babies. A little thing like cooking has produced these enormous specieal changes? I think of this as the most significant increase in the quality of food in the history of mammals and maybe in the history of life. Thank you for helping us improve PBS Video.
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