What is the effect of adding salt to the water when cooking pasta?
The salt adds flavor, but it also helps reduce the gelation 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 gelation.
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.
The addition of salt has at least 2 things going for it:
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)
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.
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.
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.
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.
I am really surprised that there was no answer above relating to the simple fact that adding even half a teaspoon salt to the boiling water serves this purpose:
- the sodium helps fill water molecules, which...
- reduces the transfer of vitamins, especially B-vitamins from noodles into the cooking water...
- which then gets thrown out as one drains the boiled noodles along with all those vitamins in that water.
That's also why I have stopped rinsing the boiled noodles, which washes off and leaches out more vitamins down the sink-drain.
If you drain noodles after boiling and don't want them to stick together, just run a Stick of butter very fast through the whole batch, which immediately improves the flavor, or put your thumb almost totally over the top of a bottle of first-pressed olive oil, and sprinkle a teaspoon or so over that batch of noodles and stir fast.
I have thereby never had any problems of sticky lumps, when stored in the refrigerator, and I have preserved a better level of nutrition.
It has to do with Osmosis (https://en.wikipedia.org/wiki/Osmosis). The saltier the water the less water gets pulled in by the pasta. Adding salt will keep your pasta nice and firm and not too bloated. That is also why you should never drink distilled water in Chemistry class. The exact opposite will happen, since there are no Salts in distilled water, your cells having a higher salt level will pull in all the water literally making them pop.