Q. Is there any information on the amount of salt that is absorbed when cooking in salted water that is drained off, e.g. pasta?
A. See this article:
Albrecht, Asp, Buzzard, "Contents and Retentions of Sodium and Other Minerals in Pasta Cooked in Unsalted and Salted Water". Cereal Chemistry, 1987. 64(2): 106 - 109.
From Cook's Illustrated, November, 2014
How Much Sodium Does Salted Water Add to Cooked Pasta?
"When boiling pasta in salted cooking water, just how much salt does the pasta absorb? Does it vary by pasta shape?
Adding salt to pasta’s cooking water ensures that the pasta is flavorful. Throughout the years we’ve zeroed in on a preferred ratio of 1 tablespoon of table salt to 4 quarts of cooking water per pound of pasta for the most well-seasoned pasta of any shape or size.
We were curious to find out exactly how much sodium actually makes it into the pasta, so we sent samples of six different shapes—spaghetti, linguine, penne, rigatoni, campanelle, and orzo—all cooked al dente according to our method, to an independent lab for analysis.
The results? Give or take a few milligrams of sodium, all the shapes absorbed about the same amount of salt: 1/16 teaspoon per 4-ounce serving or a total of 1/4 teaspoon per pound of pasta. The Dietary Guidelines for Americans recommend less than 2,300 milligrams daily for people under 51 and less than 1,500 milligrams for those 51 and older, so even if you are watching your sodium intake, the amount pasta actually absorbs is so small that it’s probably not an issue."