J. Kenji López-Alt is a restaurant-trained chef and former Editor at Cook’s Illustrated magazine, as well as the author of The New York Times best-selling cookbook The Food Lab: Better Home Cooking Through Science. In this video, he runs through several examples of kitchen conventional wisdom that aren’t really steeped in wisdom. What’s the best way to peel a boiled egg? How much water should you boil your pasta in? Does searing meat really seal in juices? The answers might not be what you expect.
J. Kenji López-Alt: Kitchen information is passed down from chef to cook or from grandmother to daughter or from father to son. And a lot of times those kitchen things go untested. When you start to test them, you find out that a lot of excepted wisdom actually isn't really true. One of the big ones is cooking pasta. I was always told to cook pasta in a huge volume of water about a gallon per pound of pasta. You actually want to use much less water than that. So the reason people say to use a lot of water is because they'll say that a larger volume of water, when you add the pasta to it, the temperature drops less and therefore it comes to a boil faster and you want your pasta to cook at a rolling boil. If you actually test it side by side, cook the same amount of pasta in a gallon of boiling water versus a quart of boiling water, both of the same heat, add to the pot at the same time, you'll find that the smaller pot actually returns to a boil faster than the large pot does. And that's because no matter the starting volume, the amount of energy that you need to add to a pot once you've added the pasta to it is the amount of energy that it takes to take that pasta from room temperature to 212 degrees. That's when the water is going to return back to a boil. And no matter what the size of the pot that's the same amount of energy. The big pot has the disadvantage of having a much larger surface area so it actually loses energy faster to the outside environment than a small pot does. So a small pot will come to a boil faster; you'll use less water, which is good. And then finally the water in the small pot, once you're done cooking the pasta, will be a little bit starchier; it will have a higher concentration of washed-off starches from the pasta. And that's a good thing because when you then take that water, when you're tossing your pasta with the sauce, you take a little bit of that water, add it to the sauce. It helps thicken it a little bit and it helps it really blind to the pasta much better. So you end up with using less energy, less time, and a better tasting end result. So less water for your pasta is number one.
Another big one is that searing meat will seal in juices. And this has been disapproved many, many times, but you here still hear it said. You still see people say start your meat over very high heat because you want to seal in the juices so that they can't escape. It doesn't actually seal in juices. And if you've ever cooked like a relatively thin steak on a grill, it's very easy to see this. You grill it one side down, develop a nice crust, flip it over, and then as it cooks, you're going to see juices bubbling up through that surface that you just seared. So it very obviously doesn't seal in the juices. And in fact if you do this side by side, you'll find that, for instance, a prime rib. If you cook one by searing it at the beginning in a high-heat oven and then gently cooking it the rest of the way through versus the opposite way — starting it in a very gentle oven and then searing it at the very end, you'll find that the one that you do with the reverse method, the gentle heat first, sear the end will actually lose less moisture than the one that you do the traditional way. You'll end up with more evenly cooked meat; it will be juicier; and it will be more tender. And it really works side by side.
Finally, let's see. Well, there's a lot of myths about peeling eggs, boiled eggs. And this is a big question that people have. Like one of the most commonly submitted questions is what makes my eggs stick to the shell? There are many theories out there. Some people say like poke a hole in the egg; some people say cook it in water with vinegar. I did a ton of testing on this. I cooked hundreds of eggs and had a third party come in and peel them blind. They didn't know how the eggs were cooked; they didn't know how I treated them. And then afterwards I counted the number of eggs that were perfectly peeled versus the number of, like, pockmarked eggs to really see what made a difference. What I found was the only two things that really make a difference when you're peeling eggs are one, the age of the egg. You want to use older eggs. Older eggs are going to peel more easily. And then by far the most important overriding factor is the temperature of the water that you start the eggs in. So if you put eggs in cold water and bring it to a boil, the egg whites will fuse to the shell. They become very, very difficult to peel. If, on the other hand you start with a pot with already boiling water and gently lower your eggs into that they peel much more easily and it's like a night-and-day difference.