Every chef says to salt your pasta water, but few home cooks know what it actually does.
It Seasons the Pasta From Within
Salted water seasons the noodles as they absorb liquid while cooking. Food scientists explain that pasta boiled in plain water tastes flat no matter how good the sauce is. Salting the water is the only chance to season the pasta itself.
It Barely Changes the Boiling Point
Many cooks believe salt makes water boil faster. In reality, the salt in a pasta pot raises the boiling point by only a fraction of a degree. Chemists say the real benefit is flavor, not physics.
How Much Salt to Use
Italian chefs call for water that tastes like the sea, roughly one to two tablespoons of kosher salt per four to six quarts of water. Dietitians note most of the salt stays in the water you drain away, so the pasta absorbs far less sodium than people fear.
When to Add It
Add the salt after the water reaches a full boil, not before. Chefs warn that salt sitting on the pot’s bottom can pit stainless steel. Once boiling, stir it in and add the pasta right away.
Sources: Serious Eats, America’s Test Kitchen