Table salt is not pure sodium chloride. It contains traces of other substances, including calcium, an element that can toughen the skin of corn kernels during cooking. That is why it's generally a good idea to let your guests salt their corn on the cob at the table. Not only can they suit their individual preferences and taste, but the corn will also be more tender.
In any event, the toughening effect of table salt is not as pronounced today as in decades gone by. Modern salt-processing techniques remove much of the calcium before the product reaches the supermarket shelf.
** Asian Recipes