For such a simple process, few kitchen tasks can stir up as much controversy as boiling pasta. Cooks will argue long and stridently over whether to use copious quantities of water or just enough, how done is "al dente," and -- a big one -- whether to add a dollop of oil to the pot. The merits of cooking at a gentle boil or a full rolling boil are also hotly debated, though the cooking time is not affected either way.
One reason for boiling's usefulness as a cooking method is that it's predictable. The temperature of most other cooking methods is difficult to gauge without a thermometer, but at any given altitude, water always boils at the same temperature. At sea level, that temperature is 212 degrees Fahrenheit. A gentle boil and a full rolling boil both keep the water at the same temperature, but vigorous boiling turns more of the water into steam in a given length of time.
Boiling vs. Simmering
Part of the reason some cooks find their pasta is done more quickly at a full rolling boil is that they're unclear on the difference between boiling and simmering. At a boil, your pot of water will bubble steadily, and at a full rolling boil it will be violently agitated. If the water is still except for occasional bubbles, or shows no more than a gentle ripple at the top, it's actually at a simmer. Simmering temperatures can be well below the boiling temperature of water, ranging from 160 F to as high as 200 F. Lower temperatures will slow the cooking time of your pasta, especially for thicker shapes, but it will eventually cook just as thoroughly.
The Traditional Technique
The traditional technique of cooking pasta is to use a large quantity of well-salted water, brought to a full rolling boil. Advocates of this traditional technique argue the vigorous boil helps keep the noodles from sticking together, though they'll still need stirring for the first few minutes. The splash of oil some cooks add to the water helps keep foam from accumulating at the top of your water and splashing to the stove, but it can also keep your sauce from clinging to the pasta. It's better to use a larger pot, and leave enough room that drops can't easily splash over the side.
The Low-Water Technique
Inquiring cooks, such as food-science writer Harold McGee, have popularized an alternative method, which uses just enough water to cook the noodles and can be done at a simmer rather than a boil. Pasta cooked by this method can be just as good as pasta cooked traditionally, though it's less effective on long shapes such as spaghetti or linguine. Cooking this way takes slightly longer and requires regular stirring to prevent the pasta from sticking to the pot. A variant of this technique brings the pasta to a boil and lets if finish cooking without any further heat. The low-water, low temperature technique is only useful for dried commercial pasta. Fresh pasta requires boiling to reach the correct texture.
- On Food and Cooking: The Science and Lore of the Kitchen; Harold McGee
- The New York Times: How Much Water Does Pasta Really Need?
- Serious Eats: The Food Lab: A New Way to Cook Pasta?
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