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Gemelli with Asparagus, Ricotta, Arugula, and Lemon Zest
Think you know how to boil pasta? Think again:
Here's the recipe! »
My wife and doorman have got a pretty sweet deal. All they have to do is nothing, and they get hot, fresh food delivered to them several times a day. Of course, they do have to be content with eating, say, fried chicken and nothing else for a month as I test a recipe, and of course there's the never-ending supply of burgers, but all in all, they've pretty much got it made.
So you can imagine my surprise the other day when I walked into the kitchen and saw my wife cooking, and my even greater surprise when I realized she was cooking pasta—in our smallest pot—at a simmer. The water was barely covering the noodles as she stirred them to keep them submerged.
"You can't do that!" I exclaimed before launching into a diatribe about how when cooking pasta, there's always got to be at least one thing rolling, and you'd probably prefer it to be the boil of a large pot of water, and not the Italian grandmothers in their graves.
She, being the smarty-pants that she is, of course came back with the best question she could have asked: "But why?"
Obviously, my dear, you haven't cooked a lot of pasta in your time. The pasta will stick together. The starch will become too concentrated. It will cook unevenly. It will become mushy. It will be nine different sorts of horrible, each one worse than the one before. It is scientific fact that you will end up with an inedible starchy, sticky blob.
That you are reading this now is a good indicator that none of that happened. In fact, in an incredible blow to my ego, and seemingly defying the unbreakable laws of physics, the pasta came out totally fine.
(Of course, I politely—make that sulkily—declined to eat any more than a single tester piece, citing potential paradoxes in the space-time continuum as my reason).
SPOILER ALERT: It turns out that not only do you not need a large volume of water to cook pasta, but in fact, the water does not even have to be boiling.
Wait. What? Let me explain:
I, and every other trained cook I know, have been taught that when cooking pasta, you need to have a large pot of boiling water. If my wife turned out to be right, just think of the pastabilities!* This could turn my whole pasta-cooking regime on its head. Some serious testing was in order—I called downstairs and told my doorman that I hope he likes noodles, cause that's gonna be his lunch for a few days.
*Thorough apologies for that and any other horrible pasta puns that may or may not appear in this article
Watching the Pot
This actually wasn't the first time I had heard of this concept. Harold McGee wrote about it in the New York Times about a year ago. His conclusion? It works, but requires constant attention. Stirring a pot of pasta constantly for 12 minutes isn't my idea of fun, so I mostly ignored his findings. But did I judge too soon? Do I really have to stir the pot?
Here are the most common reasons I've heard for why you need to use a large volume of water:
- Reason 1. A large volume of water has a higher thermal mass, and thus keeps its temperature better than a small volume. When you drop pasta into it, it thus re-achieves a boil much faster. If you were to let the pasta sit in lukewarm water as it comes back up to temperature, it would be overcooked and mushy.
- Reason 2. A large volume of water at a rolling boil helps keep the pasta separated from each other. The pieces are constantly agitated by the water and thus cook more evenly with fewer clumps.
- Reason 3. A small volume of water will become too starchy as the pasta cooks. This will make the pasta more sticky when you drain it.
- Reason 4. That's the way grandma did it.
Those are some bold claims indeed. I decided to take a closer look at them, one by one.
To do this, it's important to first consider exactly what happens to a piece of pasta as it cooks the traditional way, in a large pot of water.
Pasta is made up of flour, water, and sometimes eggs. Essentially, it's composed of starch and protein, and not much else. Now starch molecules come aggregated into large granules that resemble little water balloons. As they get heated in a moist environment, they absorb more and more water until they finally burst, releasing the starch molecules into the water. That's why pasta always seems to stick together at the beginning of cooking—its the starch molecules coming out and acting as a sort of glue, binding the pieces to each other, and to the pot.
After this stage, the starch eventually washes away into the water (assuming that you separated the pieces of pasta by stirring), and the pasta pieces become individuals again. As the pasta cooks, the starches gradually absorb more and more water, becoming softer and more edible, while the proteins begin to denature, adding structure to the noodle (something that is much more obvious when cooking soft fresh egg-based pastas). When the stars are aligned, you'll manage to pull the pasta from the water just when the proteins have lent enough structure to keep the noodles strong and pliant, and starches have just barely softened to the perfect stage—soft, but with a bite—known as al dente.
Testing the Waters
For my first test I used gemelli. It's a nice, medium-sized pasta that I figured would give a good indication of how both thick and thin pastas would fare.
I brought three separate pots of water to a boil. One with 6 quarts of water, one with 3 quarts, and one with a mere quart and a half. After the pots came to a boil, I added the pasta. Immediately, I noticed that despite claims that a large pot of water will hold its boil better, the difference in the time it took for each pot to come back to a full boil was no more than a few seconds at most. In fact, the pot with 3 quarts actually came back to a boil faster than the one with 6 quarts!.
Fact is, when you are adding an equal amount of pasta to each pot, it may cause the temperature of the smaller pot of water to drop more drastically, but bringing the smaller volume back to a boil requires the exact same amount of energy as it does to bring the larger pot back to a boil.
Since a burner puts out energy at a fixed rate, your pot will return to boiling temperature (212°F) at the same rate no matter how much water you have. Indeed, since a large pot of water has greater surface area (and thus more places for it to lose energy to the outside environment), it may actually take longer to bring a large pot of water back to a boil.*
*Case in point: at my old apartment in Cambridge, the burners were so weak that a large pot of water would not boil at all unless I put a lid on it.
Granted, during the time it takes for the water to come back up to a boil, the smaller pot will be at a lower temperature than the bigger pot, but it's only for a short period of time—is that enough to make a difference in the finished pasta?
Nope. Tasted side by side, all three noodles were indistinguishable from each other.
I've heard it said that cooking pasta at a higher temperature also ensures textural variance throughout the piece—a firm core supplying the al dente bite, surrounded by softer, more fully cooked layers around the outside. I took a close cross-sectional look at a cooked noodle, and found that once again, in all three cases, the difference was unnoticeable. It's tough to make out in a photograph, but you can actually see the al dente core—it appears as a slightly chalky looking white ring right in the center of the noodle.
To confirm what my mouth was already telling me, I also weighed each batch of pasta before and after cooking. If the batches in the smaller pots were really cooking more slowly and thus getting waterlogged as has been suggested, you'd expect them to absorb more water, when in fact, all three batches had absorbed exactly the same amount (roughly 75% of their dry weight).
Clearly, it's time to say "pasta la vista" to Reason 1.
A Sticky Situation
So what about that other little problem—pasta sticking to itself or the pan as it cooks? Well, it's true. Drop the pasta in the water and just leave it there, and it will indeed stick to itself. But you know what? It'll do that even in a really big pot with lots of water
The problem is that first stage of cooking—the one in which starch molecules first burst and release their starch. With such a high concentration of starch right on the surface of the pasta, sticking is inevitable. However, once the starch gets rinsed away in the water, the problem is completely gone.
So the key is to stir the pasta a few times during the critical first minute or two. After that, whether the pasta is swimming in a hot tub of water or just barely covered as it is here, absolutely not sticking occurs. I was able to clean this pot with a simple rinse.
"Impastable!" you cry? Try it for yourself!
That's goodbye to reason 2.
Cloudy With a Chance of Delicious
Here's where things get really interesting.
I spent a couple years working the pasta station at a restaurant known for its pasta. We did at least a hundred covers a day, and at least three-fourths of them would have at least one pasta course. That's an awful lot of pasta to cook. I cooked it all in a large, six-slot pasta cooker that held about 15 gallons of water at a constant boil.
Now at the very beginning of the shift, the pasta water was completely clear. Obviously, as the night wore on, the water would get cloudier and cloudier, until by the end of the night, it was nearly opaque. This cloudy, starchy pasta water is the line cook's secret weapon. You see, pasta water consists of starch granules and water—the exact same ingredients that go into a cornstarch slurry.
You know—the kind you use to thicken your sauces? Well, aside from just thickening a sauce, starch also acts as an emulsifier. It physically gets in the way of tiny fat molecules, preventing them from coalescing. This means that with a bit of pasta water, even an oil-based sauce like say, aglio e olio, or cacio e pepe will emulsify in to a light, creamy sauce that is much more efficient at coating pasta, making your dish that much tastier. Think of pasta water as the diplomat of the pasta world—he's the guy who's there to help your sauce and your noodles get along.
N.B. Of course, this means that go into any restaurant that serves a lot of pasta, and chance are, the later in the night you go, the better the consistency of your sauce will be!
Following that logic, my goal should be to get the water as starchy as possible, the more efficiently to bind my sauce with. I took a look at the water drained off from the batch of pasta cooked in 1 1/2 quarts against the one cooked in 3 quarts, and the picture above is what I saw.
Notice how much cloudier the one on the left is? All the better to bind you with, my dear...
Taking this concept to the logical extreme, I tried cooking my next batch of pasta with just enough water to cover it. Granted, I had to stir it as it cooked because the water level dropped and the pasta was poking up over the top, but in the end, my pasta was still perfectly al dente, not sticky, and provided me with the liquid on the right—that's all the liquid that remained after draining it, and it was extraordinarily starchy. If that now doesn't prove conclusively to you that the whole idea of pasta getting too sticky because of the starch dissolved in the water is poppycock, then I can only imagine that you are not a man of science.
Reason 3: debunked
Feeling the Heat
Now that I was completely satisfied that I could cook pasta with less water with no problems at all, I decided to run one last series of tests. I knew that when cooking, starches start to absorb water at temperatures as low as 180°F or so (that's why a cornstarch-thickened sauce will begin to thicken well below the boiling point). If we've already proven that having a rolling boil is not necessary to cook pasta, I wondered: is it actually necessary to have a boil at all? Could I not just make sure my water was above 180°F at all times?
I brought one last small pot of water to a boil and dumped in my pasta. After allowing it to come back up to a simmer, I stirred it once to ensure that the pasta wasn't sticking to itself or the pot, immediately threw a lid on the thing, and shut off the burner, knowing that in the ten to twelve minutes it took the pasta to cook, my pot would lose at most four to five degrees, keeping it well within the 180+ comfort zone.
I have to admit: even I was a little skeptical on this one. I mean, cook pasta without even boiling it? As my timer slowly counted down, I tried to list off noodle shapes in my head alphabetically just to pasta time away. If this really works, it'd be huge, I thought. I'd never cook pasta the same way again! All that wasted heat bringing a huge pot of water to a boil and maintaining it there! Think of how cool my kitchen would stay in the summer! This method could solve our energy crisis! Or at the very least, save me a couple bucks on my gas bill each month. I'd no longer have to be such a, ahem... penne pincher.
When the timer finally went off, I opened the lid and poked around a little. So far so good. The pasta sure looked cooked, and tasting it revealed al dente perfection. Success!
Thanks to my wife, I am now a changed man (at least as far as pasta goes—I still demand that I get control at least over how the burgers are cooked around here)
Oh—and as for Reason 4? It doesn't apply to me. My grandmother was Japanese. Those times that she cooked spaghetti? She was just being an impasta.
Finally, just a few quick tips regarding both this method, and cooking pasta in general:
- Don't try it with fresh pasta. This is one case where waiting for the water to heat back up actually does result in mushy pasta, like the hand-made fettuccine above. Fresh egg pasta is simply too absorptive, and lacks any structure until the egg proteins start to set.
- It won't work with really long shapes. In order to cook pasta like this, it needs to be completely submerged in a small volume of water. Spaghetti, fettuccine, and other long shapes that need to soften before they can be fully submerged thus won't work unless you first break the noodles in half.
- Do season the water. Some people claim that adding salt helps raise the water's boiling point, thus cooking the pasta faster. Don't believe them. The difference you get is at most a half a degree or so—nowhere near enough to make a difference, particularly because as we now know, you don't even have to use boiling water. But salt is necessary for another reason: It makes the pasta taste good.
- Don't bother oiling the water, and definitely don't oil the pasta after it comes out of the pot. Oil in the pasta water just floats on the surface. It's a waste, and does nothing for helping the pasta stay separated. Besides, we've also already shown today that given a good stir at the proper moment, you should have no problem with pasta sticking anyway. Oiling the pasta after it comes out of the water is a good way to ensure that your sauce won't stick to it properly, which takes us to the next point...
- Sauce your pasta immediately Have your sauce hot and ready in a separate pan right next to the boiling pasta. As soon as you drain the pasta, transfer it to the pan with the sauce and immediately start tossing it to coat, adding reserved pasta water as necessary to adjust the consistency.
If you're really keen on saving time and energy, you can do what I do: put half the water in the pot, and heat the other half in an electric kettle as the first half heats up. Add the two together, and you've got boiled water in half the time. Then all you have to do is dump the pasta, bring it back to a boil, stir, cover, and wait. Now that's using your noodle!
Read the recipe below for exact instructions on how to cook pasta with this method.
Continue here for Gemelli with Asparagus, Ricotta, Arugula, and Lemon Zest »
About the author: J. Kenji Lopez-Alt is the Chief Creative Officer of Serious Eats where he likes to explore the science of home cooking in his weekly column The Food Lab. You can follow him at @thefoodlab on Twitter, or at The Food Lab on Facebook.