Why add salt to the water when cooking pasta?

The salt adds flavor, but it also helps reduce the gelatinization of the starch in the pasta. The starch in food is the form of microscopic grains. When these grains come into contact with water, they will trap some of it (think cornstarch in cold water), but when the water is hot they swell up like balloons and merge with each other, and you have starch gelatinization.

Another thing you may want to add to the pasta water is some acid (lemon or cream of tartar). Tap water in most cities is made alkaline, which increases the starch loss from the pasta to the water, making the pasta stickier.

It means that the pasta is seasoned as it is cooked. To see if this matters to you, cook up some pasta in plain water and then some in salted water and see if you can taste the difference.

The addition of salt has at least 2 things going for it:

1. It does help keep the pasta from cooking into water, thus improving texture (less sticky/gummy). When less of the starch and protein is leached out of the pasta, it will foam less as well! (Perform the 2 batch test, side by side. The salted water will foam less, and it will be less murky when the cooking is done)

2. It does improve the flavour (at least for most of us). Just don't go crazy with the salt, and you'll be fine!

Yes, you can omit the salt, and you can acidify the water, but neither will produce a finished product that I'd care to eat.

Personally, I add salt to water to reduce the bubbling while the water is boiling and allows me to walk away from the pot for a minute. I hate it when the pot bubbles over and some water falls over the sides of the pot. Something about the salt changes the waters ability to create bubbles. This is just my observation.

As has been mentioned, whether you add salt or not it is for taste. Salt will decrease the amount of time to boil, but only if used in significant quantity. 80% water 20% salt will only increase the boiling point of the water 4 degrees. The same volume of straight water will take longer to boil for the simple fact there is more water.

Pasta sticking is in large part due to the water itself. Most tap water is leans to the alkaline side of the chart. Adding some vinegar or lemon juice to water to raise its acidity will keep the pasta from sticking. How much? You'll have to experiment.

I have found that adding salt to pasta water helps the pasta hold the water when it comes in contact with the salt in the sauce. When the pasta was not cooked in salted water it weeps when sauce is served on top of undressed pasta. Dont know why? Just an observation.

I guess it's like trying to sear a meat over a very high heat; the higher the temperature of the water the faster the pasta gets cook (so that it doesn't absorb too much which will expand the starch contain in the pasta) meanwhile leaving the center a a tiny white dot which creates a snap when bend. Besides that I too believe besides adding flavor to the pasta, by adding olive oil to the pasta is to avoid pasta from being stick together like a lump meanwhile stirring them to ensure equal heat is all over the pasta that is being cook. Olive oil to helps to coat the pasta which will reduce the water absorbtion and in the same time increase the water temperature even more higher.

The water doesn't need to be salty like totally salty but by just adding enough salt just enough for tasting will be good enough.