How to Cook Pasta Perfectly

To cook pasta, boil it uncovered in a large pot of salted water, stirring early, until it's tender but still slightly firm at the centre (al dente). Then drain it, keeping some of the starchy water, and finish it in the sauce for a minute or two so the two bind together.

What happens as pasta cooks

Dried pasta is mostly wheat starch held in a web of protein, usually from durum semolina. In boiling water, two things happen at once:

1. Starch gelatinizes. Water moves in from the outside, and starch granules swell and soften. This is starch gelatinization. Because water penetrates from the surface inward, the outside softens first and the centre last.
2. Protein sets. The gluten proteins firm up, holding the swelling starch in place. Without this, pasta would turn to mush.

Al dente, Italian for "to the tooth," is the point where the outer layers are tender but a thin core is still firm. Cut a piece in half and you'll see a faint, opaque white dot or line in the centre.

As pasta cooks, some starch leaches out into the water. That cloudy water is valuable.

How much water and salt?

Water. The traditional guideline is about 4 L (4 qt) per 450 g (1 lb) of pasta. Plenty of water returns to the boil quickly after the pasta goes in and gives long shapes room to move. You can use less (as little as 2 L per 450 g if you stir often), which gives you starchier, more useful cooking water. Just stir more to prevent sticking.

Salt. Pasta absorbs water as it cooks, and the salt comes with it. This is your only chance to season the pasta itself.

That's about 1 percent salt by weight, well below the roughly 3.5 percent of seawater. If you're using a reduced amount of water, or your sauce is very salty (with capers, olives, anchovies or lots of cheese), scale it back. See kosher salt vs table salt for why the spoon measures differ.

Salt barely changes the boiling point. Adding it at the start or once boiling makes no practical difference to timing; adding it to boiling water just dissolves it faster.

Steps

1. Bring a large pot of water to a full rolling boil, about 4 L per 450 g of pasta.
2. Add salt, about 10 g per litre, once the water is boiling.
3. Add the pasta and stir right away, then again every minute or two for the first few minutes.
4. Keep the water at a steady boil, uncovered.
5. Start tasting 2 minutes before the package time.
6. Scoop out a mug of the starchy cooking water before draining.
7. Drain the pasta while it's still slightly firm, without rinsing.
8. Toss it in the hot sauce over medium heat for 1 to 2 minutes, adding splashes of pasta water until the sauce is glossy and clings.

Why the first two minutes matter

When pasta first hits the water, its surface starch gelatinizes into a sticky layer. Pieces that touch during this stage glue together. Stirring immediately and a few times early on keeps them apart. After 2 to 3 minutes the surface sets and sticking stops being a problem.

That's also why oil in the water doesn't help: it floats on top while the pasta sticks below.

Why you finish pasta in the sauce

Pasta water is a natural thickener and binder. Its dissolved starch helps oil or butter and water form a stable emulsion instead of separating into a greasy puddle. It also helps cheese melt smoothly instead of clumping.

Draining pasta 1 to 2 minutes early and finishing it in the pan has two benefits. The pasta absorbs flavour from the sauce instead of plain water, and the starch it releases thickens the sauce into a glossy coating. Add pasta water a few tablespoons at a time; you can always add more.

Pasta cooking times

Package times are a starting point. Always taste.

Bronze-die pasta, with its rough, matte surface, usually takes a minute or two longer but holds sauce better.

Chef Fizz says: Pasta that's going into a baked dish like lasagna or baked ziti should come out 2 to 3 minutes early. It'll keep cooking in the oven.

Common mistakes and fixes

Too small a pot with too little stirring. Long pasta clumps and cooks unevenly. Use a bigger pot or stir more often.

Under-salted water. No amount of salty sauce makes up for bland pasta. Taste the water; it should taste pleasantly seasoned, like a well-seasoned soup.

Overcooking. Mushy pasta has lost its structure and soaks up sauce instead of carrying it. Start tasting early.

Pouring all the water down the drain. Set a mug in your colander as a reminder.

Letting drained pasta sit. It keeps absorbing its own moisture and sticks together. Have the sauce ready before the pasta is.

Rinsing hot pasta. It cools the pasta and washes off the starch that helps sauce cling. Save rinsing for cold pasta salads.