The addition of salt facilitates the interaction between the water and the pasta in a number of ways, resulting in a fuller and faster heat transfer to the pasta, accelerating the changes in its internal starch and proteins, which allows it to cook completely in a shorter period of time. This is why pasta relies so heavily on the addition of salt for perfect cooking.

There are several reasons why pasta should be salted:

1. Salting raises the boiling point of water. Salting coagulates the water molecules, making the attraction between the molecules stronger and requiring higher temperatures to overcome this intermolecular attraction to bring the water to a boil. This means that the salted water will reach a higher temperature for the same amount of cooking time, which is better for the pasta to cook thoroughly.

2. Salting increases the density and viscosity of the water. This allows the water to hold more heat, and the pasta to get a fuller heat transfer, absorbing more heat in the same amount of time and becoming softer. Without salt, the heat from the water is harder to transfer to the pasta, and the result will be tough.

3. Adding salt changes the molecular structure of the water, increasing the ionic concentration of the water and dramatically increasing the number of H+ and OH- ions in the water. These pairs of ions can destroy the starch and protein structure of pasta more quickly and effectively, accelerating the softening and puffing process.

4. Neutral or slightly alkaline water (pH slightly above 7) is better for cooking pasta. The addition of salt can make the water in which the pasta is cooked reach a nearly neutral state (pH value of about 7), which is the most suitable cooking environment for pasta. If the pasta is cooked under strong acidic or alkaline conditions, the protein and starch structure will be excessively damaged and acidic or alkaline colloids will form on the surface, which will affect the taste.

5. The addition of salt also improves the interaction between pasta and water, enhancing the penetration of water molecules into the starch and proteins on the surface layer of pasta. This facilitates the contact between the water molecules and the internal components of the pasta, speeding up the cooking process.