why do you put salt into boiling water?

Question

i can't seem to reach an agreement between whether it raises or lowers the boiling point of the water. if it raises the boiling point, it would take longer for it to boil, but would cook the pasta faster right? but i thought it lowered the boiling point so that it would take longer for the pasta to cook so that there's enough time for the water to seep in to the pasta. i'd like some answers from some good italian cooks too.

Answer 1

No idea about the variety of cultural/culinary reasoning here, but here's the physical boiling point answer:

ANY time something dissolves into a solvent, it lowers the vapor pressure, which subsequently raises the boiling point. It does not matter if it is salt or sugar- Anything which will dissolve will work... of course, it helps if it isn't toxic to people, if you are planning on cooking with it.

The general equation familiar to most chem students is PV=nRT P being the pressure, V the volume, T the temp, R a constant, and n the number of moles present- the Ideal Gas Law.

Boiling occurs when the vapor pressure equals the atmospheric pressure. Heating water increases the vapor pressure over the liquid- adding a solute decreases this by a certain factor, thus requiring a much hotter liquid before boiling can occur.

So, yes, adding salt will make the water boil hotter, while at the same time taking a bit longer to boil. The hotter temperature might allow faster cooking once this temperature was reached. However, it is arguable, since the amount of salt needed to significantly decrease cooking time is rather large, there is probably another cultural culinary reason for adding only a pinch.

Answer 2

Most recipes contain instructions to add salt to the water before (or sometimes during) boiling pasta. I have seen a multitude of reasons including that the salt changes the boiling point of the water (sorry; not enough to matter) to the salt keeping the water from boiling over (not chemically possible).

There is an argument for adding the salt to enhance the flavor of the pasta but I prefer to carefully control my sodium intake and the flavor of my food. The difference in pasta boiled in salted water and unsalted water is minimal and any difference will be masked by a well made and properly seasoned sauce.

Answer 3

I put salt in my water before it boils to flavor the pasta....One cook on the Food Network says that the water you cook pasta in should "taste as salty as the sea" and I follow that advice. If I'm taking the time to cook pasta and sauce, I'm not really worried about how long it takes. Just pour another glass of Chianti and remember that a "watched pot never boils"

Answer 4

yeah, i add salt to flavor my pasta and so that it doesn't stick. it does slightly increase the boiling point but not by a significant amount. It is true that you should cook pasta on a very low boil allowing more time for the absorbtion of water. But salt really doesn't affect this process.

Answer 5

It neither raises nor lowers the boiling point but merely adds flavor to the water. Or in the case of making boiled eggs, it helps keep the shell intact so that when the eggs are cooked, the shell doesn't split or burst in the water.

Answer 6

The salt doesn't help the "boiling point" of the water at all. The salt is just added to season whatever you're boiling, whether it's pasta, potatoes, etc.

Answer 7

Putting salt in the water helps to keep the water from boiling over.

Answer 8

Salt added to water makes the water boil at a higher temperature, thus reducing cooking time. (It does not make the water boil faster.)

Answer 9

Salt raises the boiling point. It doesn't raise it significantly enough to affect the cooking time.

Answer 10

salt in the water helps the pasta to not stick together. its not to make it boil any faster ,or for flavor. c'mon all you cooks, get with it