When I wrote about water freezing and boiling myths at Interesting Thing of the Day, I had in mind the stories I’d heard about hot water freezing faster than cold water, cold water boiling faster than hot water, and so on. I think I did enough experiments to get to the bottom of what’s going on—or at least, enough to satisfy my curiosity.
What I wasn’t thinking about at the time, though, was cooking-related myths about boiling water. Such as: do you really need to add salt to the water when you’re boiling pasta? I’d always assumed that was essentially useless, because a small quantity of salt doesn’t raise the boiling point of water appreciably and there’s no need to season pasta while it cooks unless you plan to serve it plain—the flavor of any sauce will completely overwhelm whatever meager flavor you’ve added with the salt.
Last year I had the opportunity to pose this question to one of the world’s foremost food scientists, Harold McGee (see Pronunciation and Pasta). According to McGee, salt can also help keep pasta from sticking together, which is a sensible reason to use it. But he also said that, especially with thicker noodles, salt can actually increase the cooking time by slowing down the osmotic process that gets water into the center of the pasta. So if speedy cooking is a priority, you might be better off skipping the salt.