Most of us have been told at some point in our culinary careers that salting beans will cause them to toughen. It's incredible that this little bit of culinary mis-wisdom still lingers, for it couldn't be further from the truth. A simple side-by-side test can prove to you conclusively that salting beans (both the water used to soak them in and the water used to cook them) actually tenderizes the skins. It's got to do with magnesium and calcium, two ions found in the bean skins that help keep the structure of the beans' skin intact. When you soak the beans in salt water, sodium ions end up replacing some of the magnesium and calcium, effectively softening the skins. Your beans come out creamier, better seasoned, and have a much smaller likelihood of exploding while cooking.