Food & Culture

Here's Why You Shouldn't Add Oil to Your Pasta Water

Pasta is the universal ingredient, playing the starring role just as perfectly in a quick bowl of bachelor chow as it does in a time-intensive gourmet recipe. Regardless of how you like to serve it, there's really just one way to boil it — and that's without any oil.

Slip Slidin' Away

When most people make pasta, they believe they should add two things to the water. First is salt, which helps season the pasta (but doesn't make the water boil any faster, to debunk another pasta myth). The second is oil, supposedly to keep the pasta from sticking together as it boils.

The problem with this comes down to a fact everybody knows: oil and water don't mix. No matter how hot the water or how rolling the boil, water's polar molecules won't mix with oil's nonpolar molecules. That means only a tiny bit of the oil, if any at all, will even make its way onto the pasta as it boils.

In fact, adding oil does more harm than good. The pasta will get up close and personal with the oil once you drain it. At that point, all the oil is good for is leaving a slick coating on the pasta that will thwart any sauce that attempts to stick to it.

Stuck on the Penne

Pasta sticks when the starch molecules within it absorb so much hot water that they burst. That makes a bunch of starch rush out and coat the outside of the pasta pieces for a few minutes at the beginning of the cooking process. Eventually, though, it dissolves and washes away, leaving the pasta smooth again.

If the pasta is constantly moving at that key moment, it's less likely to stick to itself. That's why experts like Alton Brown recommend using a huge pot and a ton of water (never less than a gallon [roughly 4 liters]) since that gives the pasta plenty of room to move around. It's also why most recipes tell you to stir the pasta immediately at the beginning, then periodically for the rest of the cooking time.

If your problem is keeping the pasta from sticking to itself once it's done, there are a few easy fixes. The obvious first: time your pasta so that it finishes with everything else. In fact, combining the pasta with the sauce when both are still hot is the best way to ensure the pasta absorbs the most sauce. Your other option is to save a little bit of pasta water, and use that to loosen the pasta when you're ready to serve it. That does double duty, since the starch dissolved in the water helps to thicken the sauce.

For more science-based cooking tips, check out "The Food Lab: Better Home Cooking Through Science" by Kenji Lopez-Alt, the managing culinary director at Serious Eats. Any purchase you make through that link will help to support Curiosity.

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Written by Ashley Hamer November 26, 2017